GP-4988 Created flow chart function graph layout

Ghidra/Features/FunctionGraph/certification.manifest

@@ -44,6 +44,8 @@ src/main/resources/images/fgpaths.png||GHIDRA||reviewed||END|
 src/main/resources/images/fgrevblock.png||GHIDRA||reviewed||END|
 src/main/resources/images/field.header.png||GHIDRA||reviewed|Custom icon|END|
 src/main/resources/images/fullscreen_view.png||FAMFAMFAM Icons - CC 2.5||||END|
+src/main/resources/images/function_graph_flowchart.png||GHIDRA||||END|
+src/main/resources/images/function_graph_flowchart_left.png||GHIDRA||||END|
 src/main/resources/images/graph_view.png||FAMFAMFAM Icons - CC 2.5||||END|
 src/main/resources/images/id.png||FAMFAMFAM Icons - CC 2.5||||END|
 src/main/resources/images/paintbrush.png||FAMFAMFAM Icons - CC 2.5||||END|

Ghidra/Features/FunctionGraph/data/functiongraph.theme.properties

@@ -21,6 +21,8 @@ color.bg.plugin.functiongraph.paint.icon = color.palette.lightcornflowerblue
 
 
 icon.plugin.functiongraph.layout.experimental = package_development.png
+icon.plugin.functiongraph.layout.flowchart = function_graph_flowchart.png
+icon.plugin.functiongraph.layout.flowchart.left = function_graph_flowchart_left.png
 icon.plugin.functiongraph.action.vertex.xrefs = brick_link.png
 icon.plugin.functiongraph.action.vertex.maximize = fullscreen_view.png
 icon.plugin.functiongraph.action.vertex.minimize = graph_view.png

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/FunctionGraph.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -442,7 +442,8 @@ public class FunctionGraph extends GroupingVisualGraph<FGVertex, FGEdge> {
 
 	public void setRootVertex(FGVertex rootVertex) {
 		if (this.rootVertex != null) {
-			throw new IllegalStateException("Cannot set the root vertex more than once!");
+			this.rootVertex = rootVertex;
+			return;
 		}
 
 		this.rootVertex = rootVertex;
@@ -586,6 +587,7 @@ public class FunctionGraph extends GroupingVisualGraph<FGVertex, FGEdge> {
 
 		FGLayout originalLayout = getLayout();
 		FGLayout newLayout = originalLayout.cloneLayout(newGraph);
+		newGraph.rootVertex = rootVertex;
 
 		// setSize() must be called after setGraphLayout() due to callbacks performed when 
 		// setSize() is called

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/FunctionGraphFactory.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -34,7 +34,7 @@ import ghidra.program.model.listing.Function;
 import ghidra.program.model.listing.Program;
 import ghidra.program.model.symbol.FlowType;
 import ghidra.util.Msg;
-import ghidra.util.SystemUtilities;
+import ghidra.util.Swing;
 import ghidra.util.exception.CancelledException;
 import ghidra.util.task.TaskMonitor;
 
@@ -184,7 +184,7 @@ public class FunctionGraphFactory {
 	private static String layoutGraph(Function function, FGController controller,
 			FunctionGraph functionGraph, TaskMonitor monitor) throws CancelledException {
 
-		if (!performSwingThreadRequiredWork(functionGraph)) {
+		if (!performSwingThreadRequiredWork(functionGraph, monitor)) {
 			return null;// shouldn't happen
 		}
 
@@ -214,19 +214,21 @@ public class FunctionGraphFactory {
 			"\" (try another layout)";
 	}
 
-	private static boolean performSwingThreadRequiredWork(FunctionGraph functionGraph) {
-		final Collection<FGVertex> vertices = functionGraph.getVertices();
-		try {
-			SystemUtilities.runSwingNow(() -> {
-				for (FGVertex v : vertices) {
-					v.getComponent();
-				}
-			});
-			return true;
-		}
-		catch (Exception e) {
-			return false;
+	private static boolean performSwingThreadRequiredWork(FunctionGraph functionGraph,
+			TaskMonitor monitor) throws CancelledException {
+
+		Collection<FGVertex> vertices = functionGraph.getVertices();
+		monitor.initialize(vertices.size(), "Building vertex components");
+		for (FGVertex v : vertices) {
+			monitor.increment();
+			try {
+				Swing.runNow(v::getComponent);
+			}
+			catch (Exception e) {
+				return false;
+			}
 		}
+		return true;
 	}
 
 	private static boolean isEntry(CodeBlock codeBlock) {

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/ExperimentalLayoutProvider.java

@@ -1,35 +0,0 @@
-/* ###
- * IP: GHIDRA
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * 
- *      http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package ghidra.app.plugin.core.functiongraph.graph.layout;
-
-import javax.swing.Icon;
-
-import generic.theme.GIcon;
-
-public abstract class ExperimentalLayoutProvider extends FGLayoutProviderExtensionPoint {
-
-	private static final Icon ICON = new GIcon("icon.plugin.functiongraph.layout.experimental");
-
-	@Override
-	public Icon getActionIcon() {
-		return ICON;
-	}
-
-	@Override
-	public int getPriorityLevel() {
-		return -100; // below the others
-	}
-}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/AbstractFlowChartLayout.java

@@ -0,0 +1,245 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.awt.Rectangle;
+import java.awt.Shape;
+import java.awt.geom.Point2D;
+import java.util.*;
+import java.util.function.Function;
+
+import ghidra.graph.*;
+import ghidra.graph.graphs.DefaultVisualGraph;
+import ghidra.graph.viewer.VisualEdge;
+import ghidra.graph.viewer.VisualVertex;
+import ghidra.graph.viewer.layout.*;
+import ghidra.graph.viewer.vertex.VisualGraphVertexShapeTransformer;
+import ghidra.util.exception.CancelledException;
+
+/**
+ * Base class for graph layouts that layout a graph based on a tree structure with orthogonal edge
+ * routing.
+ * <P>
+ * The basic algorithm is to convert the graph to a tree and then, working bottom up in the tree,
+ * assign each vertex to a {@link GridLocationMap}. This is done by assigning each leaf
+ * vertex in its own simple 1x1 grid and them merging grids for sibling children side by side as
+ * you work up the tree. Merging sub-tree grids is done by shifting child grids to the right as 
+ * each child grid is merged into the first (left most) child grid. The amount to shift a grid
+ * before it is merged is done by comparing the maximum column values for each row from the left 
+ * grid to the minimum column values for each row from the right grid and finding the minimum shift
+ * need such that no rows overlap. This way, grids are stitched together sort of like a jig-saw
+ * puzzle.
+ * <P>
+ * Once the vertices are place in the grid, edge articulations are computed so that edges are
+ * routed orthogonally using an {@link OrthogonalEdgeRouter}.
+ * <P>
+ * 
+ * To position the vertices and edges in layout space, it uses an 
+ * {@link OrthogonalGridToLayoutMapper} to size the grid and map grid points to layout points. 
+ *
+ * @param <V> the vertex type
+ * @param <E> the edge type
+ */
+
+public abstract class AbstractFlowChartLayout<V extends VisualVertex, E extends VisualEdge<V>>
+		extends AbstractVisualGraphLayout<V, E> {
+	protected Comparator<E> edgeComparator;
+	protected boolean leftAligned;
+
+	protected AbstractFlowChartLayout(DefaultVisualGraph<V, E> graph,
+			Comparator<E> edgeComparator, boolean leftAligned) {
+		super(graph, "Flow Chart");
+		this.edgeComparator = edgeComparator;
+		this.leftAligned = leftAligned;
+	}
+
+	@Override
+	protected GridLocationMap<V, E> performInitialGridLayout(VisualGraph<V, E> g)
+			throws CancelledException {
+
+		V root = getRoot(g);
+
+		GDirectedGraph<V, E> tree = GraphAlgorithms.toTree(g, root, edgeComparator);
+		GridLocationMap<V, E> grid = computeGridLocationMap(g, tree, root);
+
+		OrthogonalEdgeRouter<V, E> router = new OrthogonalEdgeRouter<>(grid);
+		router.setColumnExclusionFunction(e -> getExcludedCols(grid, tree, e));
+		router.computeAndSetEdgeArticulations(g.getEdges());
+
+		return grid;
+	}
+
+	@Override
+	protected LayoutPositions<V, E> positionInLayoutSpaceFromGrid(VisualGraph<V, E> g,
+			GridLocationMap<V, E> grid) throws CancelledException {
+
+		boolean isCondensed = isCondensedLayout();
+		Function<V, Shape> transformer = new VisualGraphVertexShapeTransformer<>();
+
+		OrthogonalGridToLayoutMapper<V, E> layoutMap =
+			new OrthogonalGridToLayoutMapper<V, E>(grid, transformer, isCondensed);
+
+		Map<V, Point2D> vertexMap = layoutMap.getVertexLocations();
+		Map<E, List<Point2D>> edgeMap = layoutMap.getEdgeLocations(vertexMap);
+
+		LayoutPositions<V, E> positions = LayoutPositions.createNewPositions(vertexMap, edgeMap);
+
+		// DEGUG triggers grid lines to be printed; useful for debugging
+		// VisualGraphRenderer.setGridPainter(new GridPainter(layoutMap.getGridCoordinates()));
+
+		layoutMap.dispose();
+		return positions;
+	}
+
+	protected abstract V getRoot(VisualGraph<V, E> g);
+
+	@Override
+	public boolean usesEdgeArticulations() {
+		return true;
+	}
+
+	@Override
+	protected Point2D getVertexLocation(V v, Column<V> col, Row<V> row,
+			Rectangle bounds) {
+		return getCenteredVertexLocation(v, col, row, bounds);
+	}
+
+	/**
+	 * Creates a GridLocationMap for the subtree rooted at the given vertex. It does this by
+	 * recursively getting grid maps for each of its children and then merging them together
+	 * side by side.
+	 * @param g the original graph
+	 * @param tree the graph after edge removal to convert it into a tree
+	 * @param v the root of the subtree to get a grid map for
+	 * @return a GridLocationMap with the given vertex and all of its children position in the 
+	 * grid.
+	 */
+	private GridLocationMap<V, E> computeGridLocationMap(GDirectedGraph<V, E> g,
+			GDirectedGraph<V, E> tree, V v) {
+
+		Collection<E> edges = tree.getOutEdges(v);
+
+		if (edges.isEmpty()) {
+			GridLocationMap<V, E> grid = new GridLocationMap<>(v, 1, 1);
+			return grid;
+		}
+
+		// get all child grids and merge them side by side
+
+		List<E> sortedEdges = new ArrayList<>(edges);
+		sortedEdges.sort(edgeComparator);
+		E edge = sortedEdges.get(0);
+		V child = edge.getEnd();
+		int totalEdges = sortedEdges.size();
+
+		GridLocationMap<V, E> childGrid = computeGridLocationMap(g, tree, child);
+		int leftChildRootCol = childGrid.getRootColumn();
+		int rightChildRootCol = leftChildRootCol;
+		for (int i = 1; i < totalEdges; i++) {
+			edge = sortedEdges.get(i);
+			child = edge.getEnd();
+			GridLocationMap<V, E> nextGrid = computeGridLocationMap(g, tree, child);
+			int shift = merge(childGrid, nextGrid, i, totalEdges);
+			rightChildRootCol = nextGrid.getRootColumn() + shift;
+		}
+		int rootCol = (leftChildRootCol + rightChildRootCol) / 2;
+		if (leftAligned) {
+			rootCol = 1;
+		}
+		GridLocationMap<V, E> grid = new GridLocationMap<>(v, 1, rootCol);
+		grid.add(childGrid, 2, 0);  // move child grid down 2: 1 for new root, 1 for edge row
+
+		return grid;
+	}
+
+	private int merge(GridLocationMap<V, E> leftGrid, GridLocationMap<V, E> rightGrid, int i,
+			int totalEdges) {
+
+		GridRange[] ranges = leftGrid.getVertexColumnRanges();
+		GridRange[] otherRanges = rightGrid.getVertexColumnRanges();
+
+		int shift = computeShift(ranges, otherRanges);
+
+		leftGrid.add(rightGrid, 0, shift);
+		return shift;
+
+	}
+
+	private int computeShift(GridRange[] ranges, GridRange[] otherRanges) {
+		int shift = 0;
+		int commonHeight = Math.min(ranges.length, otherRanges.length);
+		for (int i = 0; i < commonHeight; i++) {
+			GridRange range = ranges[i];
+			GridRange otherRange = otherRanges[i];
+			int myMax = range.max;
+			int otherMin = otherRange.min;
+			if (myMax >= otherMin - 1) {
+				int diff = myMax - otherMin + 2; // we want 1 empty column between
+				shift = Math.max(shift, diff);
+			}
+		}
+		return shift;
+	}
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public VisualGraph<V, E> getVisualGraph() {
+		return (VisualGraph<V, E>) getGraph();
+	}
+
+	/**
+	 * Returns a range of columns that we don't want to attempt to perform column routing through.
+	 * Specifically, this is for back edges where we don't want them to route through columns that
+	 * cut through any of its parents sub trees. This will force the routing algorithm to route
+	 * around a nodes containing sub-tree instead of through it.
+	 * @param grid the grid map that will be examined to find a routing column that doesn't
+	 * have any blocking vertices.
+	 * @param tree the tree version of the original graph
+	 * @param e the edge to examine to find its parent's subtree column bounds
+	 * @return a minimum and maximum column index through which the back edge should not be routed
+	 */
+	private GridRange getExcludedCols(GridLocationMap<V, E> grid, GDirectedGraph<V, E> tree, E e) {
+		GridRange range = new GridRange();
+		V v = e.getStart();
+		V ancestor = e.getEnd();
+		boolean isBackEdge = grid.row(v) >= grid.row(ancestor);
+		if (!isBackEdge) {
+			// no exclusions
+			return new GridRange();
+		}
+
+		V parent = getParent(tree, v);
+		while (parent != null) {
+			Collection<V> children = tree.getSuccessors(parent);
+			for (V child : children) {
+				range.add(grid.col(child));
+			}
+			parent = getParent(tree, parent);
+			if (parent == ancestor) {
+				break;
+			}
+		}
+		return range;
+	}
+
+	private V getParent(GDirectedGraph<V, E> tree, V v) {
+		Collection<V> predecessors = tree.getPredecessors(v);
+		if (predecessors == null || predecessors.isEmpty()) {
+			return null;
+		}
+		return predecessors.iterator().next();
+	}
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/ColSegmentList.java

@@ -0,0 +1,238 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.*;
+
+import ghidra.graph.viewer.layout.GridPoint;
+
+/**
+ * Maintains a collection of ColumnSegments for the same grid column. 
+ *
+ * @param <E> edge type
+ */
+public class ColSegmentList<E> {
+	private List<ColumnSegment<E>> edgeSegments = new ArrayList<>();
+	private int col;
+	private long minY = Integer.MAX_VALUE;
+	private long maxY = Integer.MIN_VALUE;
+
+	public ColSegmentList(int col) {
+		this.col = col;
+	}
+
+	public int getCol() {
+		return col;
+	}
+
+	public ColSegmentList(ColumnSegment<E> segment) {
+		super();
+		addSegment(segment);
+		this.col = 0;
+	}
+
+	/**
+	 * Assigns offsets for overlapping column segments. Parallel overlapping edges must be offset
+	 * from each other when assigned to layout space to avoid drawing over each other. Each
+	 * edge offset represents 1/2 the edge spacing distance. The reason offsets are assigned 2
+	 * apart from each other is so that even numbers of columns can be centered. So for example,
+	 * a column with 3 parallel edges are assigned offsets of -2,0,2, but 4 edges would be assigned
+	 * -3,-1, 1, 3. (offset in each direction by 1/2 of an edge spacing)
+	 */
+	public void assignOffsets() {
+		// First partition the column segments into non-overlapping groups. Since column segments
+		// may attach to vertices, it is easier to center them on the vertices if not trying to
+		// consider all the segments in a column at the same time.
+		List<ColSegmentList<E>> groups = sortIntoNonOverlappingGroups(edgeSegments);
+		for (ColSegmentList<E> group : groups) {
+			assignOffsets(group);
+		}
+	}
+
+	/**
+	 * Checks if the the range of y values in a given column segment list intersects the
+	 * range of y values in this column segment.
+	 * @param other the column segment list to compare
+	 * @return true if they intersect ranges.
+	 */
+	boolean intersects(ColSegmentList<E> other) {
+		if (minY > other.maxY) {
+			return false;
+		}
+		if (other.minY > maxY) {
+			return false;
+		}
+		return true;
+	}
+
+	ColumnSegment<E> getSegment(E edge, GridPoint startPoint) {
+		for (ColumnSegment<E> edgeSegment : edgeSegments) {
+			if (edgeSegment.edge.equals(edge) && edgeSegment.startsAt(startPoint)) {
+				return edgeSegment;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public String toString() {
+		return edgeSegments.toString();
+	}
+
+	int getMinOffset() {
+		int minOffset = 0;
+		for (EdgeSegment<E> edgeSegment : edgeSegments) {
+			minOffset = Math.min(minOffset, edgeSegment.getOffset());
+		}
+		return minOffset;
+	}
+
+	int getMaxOffset() {
+		int maxOffset = 0;
+		for (EdgeSegment<E> edgeSegment : edgeSegments) {
+			maxOffset = Math.max(maxOffset, edgeSegment.getOffset());
+		}
+		return maxOffset;
+	}
+
+	void addSegment(ColumnSegment<E> segment) {
+		edgeSegments.add(segment);
+		minY = Math.min(minY, segment.getVirtualMinY());
+		maxY = Math.max(maxY, segment.getVirtualMaxY());
+	}
+
+	private void assignOffsets(ColSegmentList<E> group) {
+		// First sort the column segments in a left to right ordering.
+		Collections.sort(group.edgeSegments);
+
+		// Column segments are extend both to the right and left of the grid line, so first
+		// find a starting edge to assign to 0 and then work in both directions giving offsets
+		// to columns to avoid overlaps.
+
+		// see if there is a natural center line (from a vertex to vertex in one straight line)
+		int naturalCenter = findNaturalCenter(group);
+		int centerIndex = naturalCenter >= 0 ? naturalCenter : group.edgeSegments.size() / 2;
+		assignOffsets(group, centerIndex);
+
+		// if used an arbitrary center index, our edges might not be centered around
+		// the grid line, so adjust the offsets so the are.
+		if (naturalCenter < 0) {
+			int bias = group.getMaxOffset() + group.getMinOffset();
+			int adjustment = -bias / 2;
+			for (EdgeSegment<E> segment : group.edgeSegments) {
+				segment.setOffset(segment.getOffset() + adjustment);
+			}
+		}
+	}
+
+	private void assignOffsets(ColSegmentList<E> group, int center) {
+		List<ColSegmentList<E>> nonOverlappingSegments = new ArrayList<>();
+
+		// assign negative offsets to column segments to the left of the center segment.
+		for (int i = center; i >= 0; i--) {
+			ColumnSegment<E> segment = group.edgeSegments.get(i);
+			assignOffsets(nonOverlappingSegments, segment, -2); // 2 to keep edges two offsets apart
+		}
+
+		// remove all the previous results except for the columm as we still need to check
+		// for overlap against columns that have been assigned offset 0
+		for (int i = nonOverlappingSegments.size() - 1; i > 0; i--) {
+			nonOverlappingSegments.remove(i);
+		}
+
+		// assign positive offsets to column segments to the right of the center segment.
+		for (int i = center + 1; i < group.edgeSegments.size(); i++) {
+			ColumnSegment<E> segment = group.edgeSegments.get(i);
+			assignOffsets(nonOverlappingSegments, segment, 2); // 2 to keep edges two offsets apart
+		}
+	}
+
+	private void assignOffsets(List<ColSegmentList<E>> nonOverlappingSegments,
+			ColumnSegment<E> segment, int stepSize) {
+
+		// Find lowest offset group that the given segment can be added without an overlap.
+		// Start looking at the group with highest offsets first and work towards the 0 
+		// offset group to ensure that overlapping segments don't lose the ordering that
+		// has already been establish. In other words, for a segment to be allowed to be
+		// given a 0 offset (because it doesn't overlap any segments in that group), it must
+		// also not overlap any existing groups with higher offsets. (Otherwise the ordering
+		// we created to minimize edge crossings will be lost)
+
+		int i = nonOverlappingSegments.size() - 1;
+		for (; i >= 0; i--) {
+			if (nonOverlappingSegments.get(i).hasOverlappingSegment(segment)) {
+				break;
+			}
+		}
+
+		// we either broke at a group we overlap or we are at -1. Either way, we get added
+		// to the next offset group.
+		i++;
+		if (i >= nonOverlappingSegments.size()) {
+			nonOverlappingSegments.add(new ColSegmentList<E>(i));
+		}
+		// if adjusting to the left, offsets are negative
+		int offset = i * stepSize;
+		segment.setOffset(offset);
+		nonOverlappingSegments.get(i).addSegment(segment);
+	}
+
+	private boolean hasOverlappingSegment(ColumnSegment<E> segment) {
+		for (ColumnSegment<E> edgeSegment : edgeSegments) {
+			if (segment.overlaps(edgeSegment)) {
+				return true;
+			}
+		}
+		return false;
+
+	}
+
+	private int findNaturalCenter(ColSegmentList<E> group) {
+		for (int i = 0; i < group.edgeSegments.size(); i++) {
+			ColumnSegment<E> edgeSegment = group.edgeSegments.get(i);
+			if (edgeSegment.points.size() == 2) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	private List<ColSegmentList<E>> sortIntoNonOverlappingGroups(List<ColumnSegment<E>> segments) {
+		List<ColSegmentList<E>> groups = new ArrayList<>(segments.size());
+		for (ColumnSegment<E> segment : segments) {
+			groupSegment(groups, segment);
+		}
+		return groups;
+	}
+
+	private void groupSegment(List<ColSegmentList<E>> groups, ColumnSegment<E> segment) {
+		ColSegmentList<E> newGroup = new ColSegmentList<E>(segment);
+		for (int i = groups.size() - 1; i >= 0; i--) {
+			if (newGroup.intersects(groups.get(i))) {
+				newGroup.merge(groups.get(i));
+				groups.remove(i);
+			}
+		}
+		groups.add(newGroup);
+	}
+
+	private void merge(ColSegmentList<E> segmentList) {
+		edgeSegments.addAll(segmentList.edgeSegments);
+		minY = Math.min(minY, segmentList.minY);
+		maxY = Math.max(maxY, segmentList.maxY);
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/ColumnSegment.java

@@ -0,0 +1,346 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.List;
+
+import ghidra.graph.viewer.layout.GridPoint;
+
+/**
+ * Vertical edge segments of an edge with articulation points. Each pair of points in the list
+ * of articulation points corresponds to either a column segment or a row segment. There is
+ * a built-in assumption in the sorting algorithm that the list of articulation points always
+ * start and end with a column segment. See {@link EdgeSegment} for more information.
+ *
+ * @param <E> The edge type
+ */
+public class ColumnSegment<E> extends EdgeSegment<E> implements Comparable<ColumnSegment<E>> {
+
+	// specifies the orientation of the row attached to this segment (either top or bottom)
+	enum RowOrientation {
+		LEFT, 		// the attached row extends to the left of this column
+		TERMINAL, 	// there is no attached row since this segment ends at a vertex. 
+		RIGHT		// the attached row extends to the right of this column
+	}
+
+	private RowSegment<E> next;
+	private RowSegment<E> previous;
+
+	/**
+	 * Constructs the first segment which is always a column segment. This constructor will
+	 * also create all the follow-on segments which can be retrieved via the {@link #nextSegment()}
+	 * method.
+	 * @param e the edge to create segments for
+	 * @param points the articulation points for the edge.
+	 */
+	public ColumnSegment(E e, List<GridPoint> points) {
+		this(null, e, points, 0);
+	}
+
+	/**
+	 * Package method for creating the column segments at a specific pointIndex.
+	 * @param previous the row segment the precedes this column segment
+	 * @param e the edge this segment is for
+	 * @param points the list of articulation points for the edge
+	 * @param pointIndex the index into the points list that is the first point for this segment
+	 */
+	ColumnSegment(RowSegment<E> previous, E e, List<GridPoint> points, int pointIndex) {
+		super(e, points, pointIndex);
+		this.previous = previous;
+		if (pointIndex < points.size() - 2) {
+			next = new RowSegment<E>(this, e, points, pointIndex + 1);
+		}
+	}
+
+	/**
+	 * Returns the grid column index this column segment.
+	 * @return the grid column index this column segment
+	 */
+	public int getCol() {
+		return points.get(pointIndex).col;
+	}
+
+	/**
+	 * Return the index of the row where this column segment starts. Note that this is different
+	 * from the top row. The start row is in the order of the articulation points whereas the top
+	 * row is always the spatially upper (lower row index) row of either the start row or end row.
+	 * @return the index of the grid row for the start point of this segment
+	 */
+	public int getStartRow() {
+		return points.get(pointIndex).row;
+	}
+
+	/**
+	 * Return the index of the row where this column segment ends. Note that this is different
+	 * from the bottom row. The end row is in the order of the articulation points. The bottom row
+	 * is always the spatially lower (higher row index) row of either the start row or end row.
+	 * @return the index of the grid row for the end point of this segment
+	 */
+	public int getEndRow() {
+		return points.get(pointIndex + 1).row;
+	}
+
+	@Override
+	public int compareTo(ColumnSegment<E> other) {
+		// To make the comparison reversible and transitive, it is important that we are
+		// consistent in the order we compare segments. We arbitrarily chose to always compare
+		// the order by following the shape of the top and only considering the shape on the bottom
+		// if the tops are equal.
+		//
+		// NOTE: Segments are compared by following the next or previous segments until one of the
+		// segments definitively determines the order. When comparing segments in a particular
+		// direction, is is important not to directly call the compareTo methods as that could result
+		// in an infinite loop. Instead, when comparing in a particular direction, just directly
+		// use the appropriate direction comparison so that it will follow that direction until
+		// it finds a difference or it simply returns 0, in which case the original to
+		// compareTo can then try the other direction. As a consequence of this, the basic obvious
+		// comparison of the grid columns first had to be moved into both the compareTops and the
+		// compareBottoms.
+
+		int result = compareTops(other);
+		if (result == 0) {
+			result = compareBottoms(other);
+		}
+		return result;
+	}
+
+	/**
+	 * Compares column segments strictly based  on the relationship of the connected rows at the top
+	 * of the segments. 
+	 * @param other the other column segment to compare
+	 * @return  a negative integer, zero, or a positive integer as this object
+	 *          is less than, equal to, or greater than the specified object.
+	 */
+	public int compareTops(ColumnSegment<E> other) {
+		// first, just check the columns of this segment and the other, if the columns are
+		// not the same, then one column clearly is to the left of the other. 
+
+		int result = getCol() - other.getCol();
+		if (result != 0) {
+			return result;
+		}
+
+		// We are in the same grid column,so the order is determined by the segment at the
+		// top of the column. There are 3 possible orientations for the top row. 1) it can
+		// extend to the left of our column, it can be a terminal point, or it can extend to the
+		// right. If our orientation is not the same as the other column segment, the order is
+		// simply LEFT < TERMINAL < RIGHT in order to reduce edge crossings. Edges on the left
+		// go left and edges on the right go right, so they won't cross each other.
+
+		RowOrientation myTopRowOrientation = getOrientationForTopRow();
+		RowOrientation otherTopRowOrientation = other.getOrientationForTopRow();
+
+		// if they are not the same, then LEFT < TERMINAL < RIGHT
+		if (myTopRowOrientation != otherTopRowOrientation) {
+			return myTopRowOrientation.compareTo(otherTopRowOrientation);
+		}
+
+		// Both this segment and the other segment have the same orientation. Compare the top
+		// row segments and use those results to determine our ordering left to right. If the
+		// top rows extend to the left, then which ever row is above (lower value), should have
+		// its associated column be to the right (higher value). Keeping lower rows (higher value)
+		// on the left allows their shape to avoid being crossed by the taller shape, which will be
+		// on the right.
+		// 
+		// And if the top rows extends the right, the inverse applies.
+
+		switch (myTopRowOrientation) {
+			case LEFT:
+				RowSegment<E> myTopRowSegment = getTopRowSegment();
+				RowSegment<E> otherTopRowSegment = other.getTopRowSegment();
+				return -myTopRowSegment.compareLefts(otherTopRowSegment);
+			case RIGHT:
+				myTopRowSegment = getTopRowSegment();
+				otherTopRowSegment = other.getTopRowSegment();
+				return myTopRowSegment.compareRights(otherTopRowSegment);
+			case TERMINAL:
+			default:
+				return 0;
+		}
+
+	}
+
+	/**
+	 * Compares column segments strictly based  on the relationship of the connected rows at the 
+	 * bottom of the segments. 
+	 * @param other the other column segment to compare
+	 * @return  a negative integer, zero, or a positive integer as this object
+	 *          is less than, equal to, or greater than the specified object.
+	 */
+	public int compareBottoms(ColumnSegment<E> other) {
+		// first, just check the columns of this segment and the other, if the columns are
+		// not the same, then one column clearly is to the left of the other.
+		int result = getCol() - other.getCol();
+		if (result != 0) {
+			return result;
+		}
+
+		// We are in the same grid column, the order is determined by the segment at the
+		// bottom of the column (we already tried the top and they were equal). There are 
+		// 3 possible orientations for the botom row. 1) it can
+		// extend to the left of our column, it can be a terminal point, or it can extend to the
+		// right. If our orientation is not the same as the other column segment, the order is
+		// simply LEFT < TERMINAL < RIGHT in order to reduce edge crossings. Edges on the left
+		// go left and edges on the right go right, so they won't cross each other.
+
+		RowOrientation myBottomRowOrientation = getOrientationForBottomRow();
+		RowOrientation otherTopRowOrientation = other.getOrientationForBottomRow();
+		// if they are not the same, then LEFT < TERMINAL < RIGHT
+		if (myBottomRowOrientation != otherTopRowOrientation) {
+			return myBottomRowOrientation.compareTo(otherTopRowOrientation);
+		}
+
+		// Both this segment and the other segment have the same orientation. Compare the bottom
+		// row segments and use those results to determine our ordering left to right. If the
+		// bottom rows extend to the left, then which ever row is above (lower value), should have
+		// its associated column be to the left (lower value). Keeping lower rows (higher value)
+		// on the right allows their shape to avoid being crossed by the taller shape, which will be
+		// on the left.
+		// 
+		// And if the top rows extends the right, the inverse applies.
+
+		switch (myBottomRowOrientation) {
+			case LEFT:
+				RowSegment<E> myBottomRowSegment = getBottomRowSegment();
+				RowSegment<E> otherBottomRowSegment = other.getBottomRowSegment();
+				return myBottomRowSegment.compareLefts(otherBottomRowSegment);
+
+			case RIGHT:
+				myBottomRowSegment = getBottomRowSegment();
+				otherBottomRowSegment = other.getBottomRowSegment();
+				return -myBottomRowSegment.compareRights(otherBottomRowSegment);
+			case TERMINAL:
+			default:
+				return 0;
+		}
+
+	}
+
+	/**
+	 * Checks if the given column segments overlaps vertically.
+	 * @param other the other column segment to compare
+	 * @return true if these would overlap if drawn with same x column coordinate 
+	 */
+	public boolean overlaps(ColumnSegment<E> other) {
+		if (getVirtualMinY() > other.getVirtualMaxY()) {
+			return false;
+		}
+		if (getVirtualMaxY() < other.getVirtualMinY()) {
+			return false;
+		}
+		return true;
+	}
+
+	@Override
+	public RowSegment<E> nextSegment() {
+		return next;
+	}
+
+	@Override
+	public RowSegment<E> previousSegment() {
+		return previous;
+	}
+
+	/**
+	 * Returns true if this is the first segment in an edge articulation point list.
+	 * @return true if this is the first segment in an edge articulation point list
+	 */
+	public boolean isStartSegment() {
+		return previous == null;
+	}
+
+	/**
+	 * Returns true if this is the last segment in an edge articulation point list.
+	 * @return true if this is the last segment in an edge articulation point list
+	 */
+	public boolean isEndSegment() {
+		return next == null;
+	}
+
+	/**
+	 * Returns a top y position assuming rows are one million pixels apart for comparison purposes. 
+	 * It takes into account the assigned offsets of the attached rows. This method depends on
+	 * row offsets having already been assigned.
+	 * @return a virtual top y position only useful for comparison purposes.
+	 */
+	public int getVirtualMinY() {
+		return Math.min(getVirtualStartY(), getVirtualEndY());
+	}
+
+	/**
+	 * Returns a bottom y position assuming rows are one million pixels apart for comparison
+	 * purposes. It takes into account the assigned offsets of the attached rows. This method
+	 * depends on row offsets having already been assigned.
+	 * @return a virtual bottom y position only useful for comparison purposes.
+	 */
+	public int getVirtualMaxY() {
+		return Math.max(getVirtualStartY(), getVirtualEndY());
+	}
+
+	private int getVirtualStartY() {
+		// start segments are given a slight downward offset for comparison purposes to 
+		// avoid being overlapped by ends segments that end on the same vertex as we begin
+		int offset = previous == null ? 1 : previous.getOffset();
+
+		return getStartRow() * 1000000 + offset;
+	}
+
+	private int getVirtualEndY() {
+		// end segments are given a slight upward offset for comparison purposes to 
+		// avoid being overlapped by ends segments that start on the same vertex as we end
+		int offset = next == null ? -1 : next.getOffset();
+		return getEndRow() * 1000000 + offset;
+	}
+
+	private RowSegment<E> getTopRowSegment() {
+		return flowsUp() ? next : previous;
+	}
+
+	private RowSegment<E> getBottomRowSegment() {
+		return flowsUp() ? previous : next;
+	}
+
+	private RowOrientation getOrientationForTopRow() {
+		if (isStartSegment()) {
+			return RowOrientation.TERMINAL;
+		}
+		RowSegment<E> topRowSegment = getTopRowSegment();
+		int topRowOtherCol = flowsUp() ? topRowSegment.getEndCol() : topRowSegment.getStartCol();
+		return topRowOtherCol < getCol() ? RowOrientation.LEFT : RowOrientation.RIGHT;
+	}
+
+	private RowOrientation getOrientationForBottomRow() {
+		if (isEndSegment()) {
+			return RowOrientation.TERMINAL;
+		}
+		RowSegment<E> bottomRowSegment = getBottomRowSegment();
+		int bottomRowOtherCol =
+			flowsUp() ? bottomRowSegment.getStartCol() : bottomRowSegment.getEndCol();
+		return bottomRowOtherCol < getCol() ? RowOrientation.LEFT : RowOrientation.RIGHT;
+	}
+
+	private boolean flowsUp() {
+		return getStartRow() > getEndRow();
+	}
+
+	public ColumnSegment<E> last() {
+		if (isEndSegment()) {
+			return this;
+		}
+		return next.last();
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/EdgeSegment.java

@@ -0,0 +1,112 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.List;
+
+import ghidra.graph.viewer.layout.GridPoint;
+
+/**
+ * Base class for edge segments that are part of an articulated edge. Basically, edge articulations
+ * are stored as a list of {@link GridPoint}s while in grid space. Each pair of points in the list
+ * of points represents either a row or column segment. These segments are useful for orthogonal 
+ * edge routing algorithms as they provide a higher level API instead of dealing directly with
+ * the points list.
+ * <P>
+ * Each segment has its related edge object and the full list of articulation points so that can
+ * also provide information on its connected segments. The point index is simply the index into
+ * the points list of the first point in the segment that this segment object represents.
+ * <P>
+ * Segments also maintain a linked list to the other segments that make up the edge which can
+ * be retrieved via the {@link #nextSegment()} and {@link #previousSegment()} methods respectively.
+ *
+ * @param <E> the edge type
+ */
+public abstract class EdgeSegment<E> {
+
+	protected E edge;
+	protected List<GridPoint> points; // this is a list of all articulations points for the edge
+	protected int pointIndex;	 	  // the index into the points of the first point in the segment
+	private int offset;				  // holds any offset assigned to this segment by edge routing
+
+	public EdgeSegment(E e, List<GridPoint> points, int pointIndex) {
+		this.edge = e;
+		this.points = points;
+		this.pointIndex = pointIndex;
+	}
+
+	public E getEdge() {
+		return edge;
+	}
+
+	/**
+	 * Sets the offset from the grid line for this segment. Edge routing algorithms will set
+	 * this value to keep overlapping segments in the same row or column for being assigned to
+	 * the same exact layout space location.
+	 * @param offset the distance from the grid line to use when assigning to layout space
+	 */
+	public void setOffset(int offset) {
+		this.offset = offset;
+	}
+
+	/**
+	 * The amount of x or y space to use when assigning to layout space to prevent this segment
+	 * from overlapping segments from other edges.
+	 * @return the offset from the grid line.
+	 */
+	public int getOffset() {
+		return offset;
+	}
+
+	@Override
+	public String toString() {
+		return String.format("%s,  i = %d, offset = %s", edge, pointIndex, offset);
+	}
+
+	/**
+	 * Returns true if this edge ends at or above its start row.
+	 * @return true if this edge ends at or above its start row
+	 */
+	public boolean isBackEdge() {
+		GridPoint start = points.get(0);
+		GridPoint end = points.get(points.size() - 1);
+		return start.row >= end.row;
+	}
+
+	/**
+	 * Returns true if this segment starts at the given point. 
+	 * @param p the grid point to check
+	 * @return true if this segment starts at the given point
+	 */
+	public boolean startsAt(GridPoint p) {
+		return points.get(pointIndex).equals(p);
+	}
+
+	/**
+	 * Returns the next edge segment after this one or null if this is the last segment. If the
+	 * this segment is a RowSegment, the next segment will be a ColumnSegment and vise-versa.
+	 * @return the next edge segment.
+	 */
+	public abstract EdgeSegment<E> nextSegment();
+
+	/**
+	 * Returns the previous edge segment before this one or null if this is the first segment. If 
+	 * the this segment is a RowSegment, the previous segment will be a ColumnSegment and 
+	 * vise-versa.
+	 * @return the previous edge segment.
+	 */
+	public abstract EdgeSegment<E> previousSegment();
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/EdgeSegmentMap.java

@@ -0,0 +1,118 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.*;
+
+import ghidra.graph.viewer.layout.GridLocationMap;
+import ghidra.graph.viewer.layout.GridPoint;
+
+/**
+ * Organizes all edge segments from a {@link GridLocationMap} into rows and column objects and 
+ * then assigns offsets to overlapping segments within a row or column. Offsets are values that
+ * represent either x or y distances that will later be added to a row segment's y coordinate or a
+ * column segment's x coordinate to keep them from overlapping in layout space.
+ * <P>
+ * The offsets have to be computed before sizing the grid because the offsets affect
+ * the size of the grid rows and columns.
+ *
+ * @param <E> the edge type
+ */
+public class EdgeSegmentMap<E> {
+
+	private Map<Integer, RowSegmentList<E>> rowSegmentMap = new HashMap<>();
+	private Map<Integer, ColSegmentList<E>> colSegmentMap = new HashMap<>();
+
+	public EdgeSegmentMap(GridLocationMap<?, E> grid) {
+		createEdgeSegments(grid);
+		assignEdgeSegmentOffsets();
+	}
+
+	/**
+	 * Returns a collection of all edge row segment lists.
+	 * @return a collection of all edge row segment lists
+	 */
+	public Collection<RowSegmentList<E>> rowSegments() {
+		return rowSegmentMap.values();
+	}
+
+	/**
+	 * Returns a collection of all edge column segment lists.
+	 * @return a collection of all edge column segment lists
+	 */
+	public Collection<ColSegmentList<E>> colSegments() {
+		return colSegmentMap.values();
+	}
+
+	/**
+	 * Finds the column segment object for the given edge and start point.
+	 * @param edge the edge for which to find its column segment object
+	 * @param gridPoint the start point for the desired segment object
+	 * @return the column segment object for the given edge and start point.
+	 */
+	public ColumnSegment<E> getColumnSegment(E edge, GridPoint gridPoint) {
+		ColSegmentList<E> colSegments = colSegmentMap.get(gridPoint.col);
+		return colSegments == null ? null : colSegments.getSegment(edge, gridPoint);
+	}
+
+	public void dispose() {
+		rowSegmentMap.clear();
+		colSegmentMap.clear();
+	}
+
+	private void createEdgeSegments(GridLocationMap<?, E> grid) {
+		for (E edge : grid.edges()) {
+
+			List<GridPoint> gridPoints = grid.getArticulations(edge);
+			ColumnSegment<E> colSegment = new ColumnSegment<E>(edge, gridPoints);
+
+			addColSegment(colSegment);
+
+			// segments always start and end with a column segment, so any additional segments
+			// will be in pairs of a row segment followed by a column segment
+			while (!colSegment.isEndSegment()) {
+				RowSegment<E> rowSegment = colSegment.nextSegment();
+				addRowSegment(rowSegment);
+				colSegment = rowSegment.nextSegment();
+				addColSegment(colSegment);
+			}
+		}
+	}
+
+	private void assignEdgeSegmentOffsets() {
+		for (RowSegmentList<E> rowSegments : rowSegmentMap.values()) {
+			rowSegments.assignOffsets();
+		}
+		for (ColSegmentList<E> colSegments : colSegmentMap.values()) {
+			colSegments.assignOffsets();
+		}
+	}
+
+	private void addRowSegment(RowSegment<E> rowSegment) {
+		int row = rowSegment.getRow();
+		RowSegmentList<E> edgeRow =
+			rowSegmentMap.computeIfAbsent(row, k -> new RowSegmentList<E>(k));
+		edgeRow.addSegment(rowSegment);
+	}
+
+	private void addColSegment(ColumnSegment<E> colSegment) {
+		int col = colSegment.getCol();
+		ColSegmentList<E> edgeCol =
+			colSegmentMap.computeIfAbsent(col, k -> new ColSegmentList<E>(k));
+		edgeCol.addSegment(colSegment);
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/FGFlowChartLayout.java

@@ -0,0 +1,98 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.Comparator;
+
+import edu.uci.ics.jung.visualization.renderers.BasicEdgeRenderer;
+import ghidra.app.plugin.core.functiongraph.graph.FGEdge;
+import ghidra.app.plugin.core.functiongraph.graph.FunctionGraph;
+import ghidra.app.plugin.core.functiongraph.graph.jung.renderer.FGEdgeRenderer;
+import ghidra.app.plugin.core.functiongraph.graph.layout.FGLayout;
+import ghidra.app.plugin.core.functiongraph.graph.vertex.FGVertex;
+import ghidra.app.plugin.core.functiongraph.mvc.FunctionGraphOptions;
+import ghidra.graph.VisualGraph;
+import ghidra.graph.viewer.layout.AbstractVisualGraphLayout;
+import ghidra.graph.viewer.layout.VisualGraphLayout;
+import ghidra.program.model.symbol.FlowType;
+import ghidra.program.model.symbol.RefType;
+
+/**
+ * Adapts the {@link AbstractFlowChartLayout} to work for {@link FunctionGraph}s.
+ */
+public class FGFlowChartLayout extends AbstractFlowChartLayout<FGVertex, FGEdge>
+		implements FGLayout {
+
+	private FunctionGraphOptions options;
+
+	protected FGFlowChartLayout(FunctionGraph graph, boolean leftAligned) {
+		super(graph, new FGEdgeComparator(), leftAligned);
+		this.options = graph.getOptions();
+	}
+
+	@Override
+	public FunctionGraph getVisualGraph() {
+		return (FunctionGraph) super.getVisualGraph();
+	}
+
+	@Override
+	public AbstractVisualGraphLayout<FGVertex, FGEdge> createClonedLayout(
+			VisualGraph<FGVertex, FGEdge> newGraph) {
+		return new FGFlowChartLayout((FunctionGraph) newGraph, leftAligned);
+	}
+
+	@Override
+	public FGLayout cloneLayout(VisualGraph<FGVertex, FGEdge> newGraph) {
+		VisualGraphLayout<FGVertex, FGEdge> clone = super.cloneLayout(newGraph);
+		return (FGLayout) clone;
+	}
+
+	@Override
+	protected boolean isCondensedLayout() {
+		return options.useCondensedLayout();
+	}
+
+	@Override
+	public BasicEdgeRenderer<FGVertex, FGEdge> getEdgeRenderer() {
+		return new FGEdgeRenderer();
+	}
+
+	private static class FGEdgeComparator implements Comparator<FGEdge> {
+		@Override
+		public int compare(FGEdge e1, FGEdge e2) {
+			return priority(e1).compareTo(priority(e2));
+		}
+
+		private Integer priority(FGEdge e) {
+			FlowType type = e.getFlowType();
+			// making fall through edges a higher priority, makes it more likely that vertices
+			// with fall through connections will be direct descendants (closer) when the graph is
+			// converted to a tree.
+			if (type == RefType.FALL_THROUGH) {
+				return 1;  // lower is more preferred
+			}
+			return 10;
+		}
+	}
+
+	@Override
+	protected FGVertex getRoot(VisualGraph<FGVertex, FGEdge> g) {
+		if (graph instanceof FunctionGraph fg) {
+			return fg.getRootVertex();
+		}
+		return null;
+	}
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/FlowChartLayoutProvider.java

@@ -0,0 +1,54 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import javax.swing.Icon;
+
+import generic.theme.GIcon;
+import ghidra.app.plugin.core.functiongraph.graph.FunctionGraph;
+import ghidra.app.plugin.core.functiongraph.graph.layout.FGLayout;
+import ghidra.app.plugin.core.functiongraph.graph.layout.FGLayoutProviderExtensionPoint;
+import ghidra.util.exception.CancelledException;
+import ghidra.util.task.TaskMonitor;
+
+/**
+ * Makes the Flow Chart Layout available for the function graph feature.
+ */
+public class FlowChartLayoutProvider extends FGLayoutProviderExtensionPoint {
+	private static final Icon ICON = new GIcon("icon.plugin.functiongraph.layout.flowchart");
+
+	@Override
+	public String getLayoutName() {
+		return "Flow Chart";
+	}
+
+	@Override
+	public Icon getActionIcon() {
+		return ICON;
+	}
+
+	@Override
+	public int getPriorityLevel() {
+		return 140;
+	}
+
+	@Override
+	public FGLayout getFGLayout(FunctionGraph graph, TaskMonitor monitor)
+			throws CancelledException {
+		return new FGFlowChartLayout(graph, false);
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/LeftAlignedFlowChartLayoutProvider.java

@@ -0,0 +1,54 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import javax.swing.Icon;
+
+import generic.theme.GIcon;
+import ghidra.app.plugin.core.functiongraph.graph.FunctionGraph;
+import ghidra.app.plugin.core.functiongraph.graph.layout.FGLayout;
+import ghidra.app.plugin.core.functiongraph.graph.layout.FGLayoutProviderExtensionPoint;
+import ghidra.util.exception.CancelledException;
+import ghidra.util.task.TaskMonitor;
+
+/**
+ * Makes the Left Aligned Flow Chart Layout available for the function graph feature.
+ */
+public class LeftAlignedFlowChartLayoutProvider extends FGLayoutProviderExtensionPoint {
+	private static final Icon ICON = new GIcon("icon.plugin.functiongraph.layout.flowchart.left");
+
+	@Override
+	public String getLayoutName() {
+		return "Flow Chart (Left)";
+	}
+
+	@Override
+	public Icon getActionIcon() {
+		return ICON;
+	}
+
+	@Override
+	public int getPriorityLevel() {
+		return 130;
+	}
+
+	@Override
+	public FGLayout getFGLayout(FunctionGraph graph, TaskMonitor monitor)
+			throws CancelledException {
+		return new FGFlowChartLayout(graph, true);
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/OrthogonalEdgeRouter.java

@@ -0,0 +1,173 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.*;
+import java.util.function.Function;
+
+import ghidra.graph.viewer.VisualEdge;
+import ghidra.graph.viewer.VisualVertex;
+import ghidra.graph.viewer.layout.*;
+
+/**
+ * Routes edges orthogonally for vertices positioned in a {@link GridLocationMap}.
+ * This algorithm creates articulation points such that outgoing edges always exit the
+ * start vertex from the bottom and enter the end vertex from the top.
+ * <P>
+ * There are only three types of edges created by this algorithm. The first
+ * type is an edge with one segment that goes directly from a start vertex straight down to an 
+ * end vertex. 
+ * <P>
+ * The second type is an edge with three segments that goes down from the start vertex,
+ * goes left or right to the column of the end vertex and then goes down to a child vertex.
+ * <P>
+ * The third type consists of 5 segments and can connect any two vertices in the graph. It starts
+ * by going down to the next row from the start vertex, then goes left or right until it finds a 
+ * column where there are no vertices between that row and the row above the end vertex. It then 
+ * goes left or right in that row to the column of the end vertex and then down to that vertex. 
+ *
+ * @param <V> the vertex type
+ * @param <E> the edge type
+ */
+
+public class OrthogonalEdgeRouter<V extends VisualVertex, E extends VisualEdge<V>> {
+	private Function<E, GridRange> excludedColumnsFunction;
+	private GridLocationMap<V, E> grid;
+	private Map<Integer, Column<V>> columnMap;
+
+	public OrthogonalEdgeRouter(GridLocationMap<V, E> grid) {
+		this.grid = grid;
+		columnMap = grid.columnsMap();
+		excludedColumnsFunction = e -> new GridRange();
+	}
+
+	/**
+	 * Computes a list of articulations points in grid space for each edge in the given collection 
+	 * and sets those points into the {@link GridLocationMap}.
+	 * @param edges computes articulations points in grid space and sets them on the grid
+	 */
+	public void computeAndSetEdgeArticulations(Collection<E> edges) {
+		for (E e : edges) {
+			V v1 = e.getStart();
+			V v2 = e.getEnd();
+			GridPoint p1 = grid.gridPoint(v1);
+			GridPoint p2 = grid.gridPoint(v2);
+			int routingCol = findRoutingColumn(e, p1, p2);
+			List<GridPoint> edgePoints = getEdgePoints(p1, p2, routingCol);
+			grid.setArticulations(e, edgePoints);
+		}
+	}
+
+	/**
+	 * Sets a function that can be used to prevent edges from being routed in  a range of columns.
+	 * One use of this is to prevent back edges from intersecting any child trees in its ancestor
+	 * hierarchy between the start vertex and the end vertex.  
+	 * @param excludedColumnsFunction the function to call to compute a range of columns to 
+	 * prevent routing edges.
+	 */
+	public void setColumnExclusionFunction(Function<E, GridRange> excludedColumnsFunction) {
+		this.excludedColumnsFunction = excludedColumnsFunction;
+	}
+
+	private int findRoutingColumn(E e, GridPoint p1, GridPoint p2) {
+		if (p2.row == p1.row + 2) {
+			return p1.col;			// direct child 
+		}
+		int startRow = Math.min(p1.row + 1, p2.row - 1);
+		int endRow = Math.max(p1.row + 1, p2.row - 1);
+		int startCol = Math.min(p1.col, p2.col);
+		int endCol = Math.max(p1.col, p2.col);
+		boolean isBackEdge = p2.row <= p1.row;
+
+		// If not a back edge, try to route in between start and end columns, but we decided not
+		// to ever route back edges in between so that back edges have C-shape or backwards C-shape
+		// and not a Z-shape.
+		if (!isBackEdge) {
+			// try if either start or end column is open
+			if (isOpenPath(p1.col, startRow, endRow)) {
+				return p1.col;
+			}
+			if (isOpenPath(p2.col, startRow, endRow)) {
+				return p2.col;
+			}
+
+			for (int col = startCol + 1; col <= endCol - 1; col++) {
+				if (isOpenPath(col, startRow, endRow)) {
+					return col;
+				}
+			}
+		}
+
+		// Get an optional excluded range where we don't want to route a specific edge. By
+		// default the range is empty, allowing any column.
+		GridRange excludedRange = excludedColumnsFunction.apply(e);
+
+		// try each each left and right column expanding outwards, starting at the columns of
+		// the start and end vertex.
+		for (int i = 1; i <= startCol; i++) {
+			int left = startCol - i;
+			int right = endCol + i;
+
+			boolean leftExcluded = excludedRange.contains(left);
+			boolean rightExcluded = excludedRange.contains(right);
+			boolean leftValid = !leftExcluded && isOpenPath(left, startRow, endRow);
+			boolean rightValid = !rightExcluded && isOpenPath(right, startRow, endRow);
+			if (leftValid) {
+				if (!rightValid) {
+					return left;
+				}
+				// if both are open, prefer left for forward edges, right for back edges
+				return p1.row < p2.row ? left : right;
+			}
+			else if (rightValid) {
+				return right;
+			}
+		}
+		return 0;	// 0 is always open as we avoid putting vertices in the 0 column
+	}
+
+	private boolean isOpenPath(int col, int startRow, int endRow) {
+		Column<V> column = columnMap.get(col);
+		if (column == null) {
+			return true;
+		}
+		return column.isOpenBetween(startRow, endRow);
+	}
+
+	private List<GridPoint> getEdgePoints(GridPoint p1, GridPoint p2, int routingCol) {
+		List<GridPoint> points = new ArrayList<GridPoint>();
+
+		points.add(p1);
+
+		if (routingCol == p1.col) {
+			if (routingCol != p2.col) {
+				points.add(new GridPoint(p2.row - 1, p1.col));
+				points.add(new GridPoint(p2.row - 1, p2.col));
+			}
+		}
+		else {
+			points.add(new GridPoint(p1.row + 1, p1.col));
+			points.add(new GridPoint(p1.row + 1, routingCol));
+			if (routingCol != p2.col) {
+				points.add(new GridPoint(p2.row - 1, routingCol));
+				points.add(new GridPoint(p2.row - 1, p2.col));
+			}
+		}
+		points.add(p2);
+		return points;
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/OrthogonalGridSizer.java

@@ -0,0 +1,181 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.awt.Rectangle;
+import java.awt.Shape;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.function.Function;
+
+import ghidra.graph.viewer.layout.*;
+
+/**
+ * Computes positions in layout space for {@link GridLocationMap}s that have orthogonally routed
+ * edges.
+ * <P>
+ * At this point, the grid has been populated with vertices at specific grid points and edges with
+ * lists of grid articulation points for their routing. Conceptually, vertices live at the 
+ * intersection of the grid lines and edges are routed along grid lines. While in grid space, 
+ * vertices have no size and edges can overlap each other along grid lines. In order to map these 
+ * virtual grid locations to points in layout space, we need to use the size of each vertex and 
+ * offsets assigned to parallel edge segments that share a grid line.
+ * <P>
+ * We first need to compute sizes for the rows and columns in the grid. For purposes of this
+ * algorithm, the size of a row N is defined to be the distance between grid line row N and grid
+ * line row N+1. The same applies to column sizes. The way vertex sizes are applied is slightly
+ * different for rows and column. Vertices are centered on grid column lines, but
+ * completely below grid row lines. So if a vertex is at grid point 1,1, all of its height is 
+ * assigned to grid row 1. But its width is split between grid column 0 and grid column 1. Edges
+ * work similarly, in that parallel horizontal edge segments extend below their grid row, but 
+ * parallel column segments are split so that some have offsets that are before the vertical 
+ * grid line and some are after.
+ * <P>
+ * The row sizing is straight forward. Even rows only contain edges and odd rows only contain
+ * vertices. Since the height of a vertex is assigned completely to one row, that row's height
+ * is simply the maximum height of all the vertices in that row, plus any row padding.
+ * <P>
+ * Column sizing is more complicated. The width of any column is going to be the the max of either
+ * 1) vertices that half extend from the left + the thickness of edges that extend the right, OR 
+ * 2) vertices that half extend from the right + the thickness of edges the extend from the left.
+ * Also, column padding is applied differently. For columns, padding is not just added to the 
+ * column width like in rows. Instead, it acts as a minimum "edge thickness". In other words if the
+ * edge thickness is less than the padding, the edge thickness doesn't make the gaps bigger. Only if
+ * the edge thickness is greater the the column padding, then it determines the gap and the 
+ * column padding contributes nothing.
+ *
+ * @param <V> the vertex type
+ * @param <E> the edge type
+ */
+public class OrthogonalGridSizer<V, E> {
+	private static final int EDGE_ROW_PADDING = 25;				// space before an edge row
+	private static final int VERTEX_ROW_PADDING = 35;			// space before a vertex vow
+	private static final int COL_PADDING = 30;					// minimum space for a column
+	private static final int CONDENSED_EDGE_ROW_PADDING = 15;
+	private static final int CONDENSED_VERTEX_ROW_PADDING = 25;
+	private static final int CONDENSED_COL_PADDING = 15;
+
+	private int[] rowHeights;
+	private int[] beforeColEdgeWidths;
+	private int[] afterColEdgeWidths;
+	private int[] colVertexWidths;
+	private int edgeSpacing;
+
+	public OrthogonalGridSizer(GridLocationMap<V, E> gridMap, EdgeSegmentMap<E> segmentMap,
+			Function<V, Shape> transformer, int edgeSpacing) {
+		this.edgeSpacing = edgeSpacing;
+		rowHeights = new int[gridMap.height()];
+		beforeColEdgeWidths = new int[gridMap.width()];
+		afterColEdgeWidths = new int[gridMap.width()];
+		colVertexWidths = new int[gridMap.width()];
+
+		addVertexSizes(gridMap, transformer);
+
+		addEdgeRowSizes(gridMap, segmentMap);
+
+		addEdgeColSizes(gridMap, segmentMap);
+	}
+
+	public GridCoordinates getGridCoordinates(boolean isCondensed) {
+		int[] rowStarts = new int[rowCount() + 1];
+		int[] colStarts = new int[colCount() + 1];
+		int vertexRowPadding = isCondensed ? CONDENSED_VERTEX_ROW_PADDING : VERTEX_ROW_PADDING;
+		int edgeRowPadding = isCondensed ? CONDENSED_EDGE_ROW_PADDING : EDGE_ROW_PADDING;
+		int colPadding = isCondensed ? CONDENSED_COL_PADDING : COL_PADDING;
+		for (int row = 1; row < rowStarts.length; row++) {
+			// edges rows are even, vertex rows are odd
+			int rowPadding = row % 2 == 0 ? edgeRowPadding : vertexRowPadding;
+			rowStarts[row] = rowStarts[row - 1] + height(row - 1, rowPadding);
+		}
+		for (int col = 1; col < colStarts.length; col++) {
+			colStarts[col] = colStarts[col - 1] + width(col - 1, colPadding);
+		}
+
+		return new GridCoordinates(rowStarts, colStarts);
+	}
+
+	private int rowCount() {
+		return rowHeights.length;
+	}
+
+	private int colCount() {
+		return colVertexWidths.length;
+	}
+
+	private int height(int row, int rowPadding) {
+		return rowHeights[row] + rowPadding;
+	}
+
+	private int width(int col, int minColPadding) {
+		int leftEdgeWidth = Math.max(afterColEdgeWidths[col], minColPadding);
+		int leftVertexWidth = colVertexWidths[col] / 2;
+		int rightEdgeWidth = 0;
+		int rightVertexWidth = 0;
+		if (col < colVertexWidths.length - 1) {
+			rightEdgeWidth = Math.max(beforeColEdgeWidths[col + 1], minColPadding);
+			rightVertexWidth = colVertexWidths[col + 1] / 2;
+		}
+
+		int width = Math.max(leftEdgeWidth + rightVertexWidth, rightEdgeWidth + leftVertexWidth);
+		width = Math.max(width, leftEdgeWidth + rightEdgeWidth);
+		return width;
+	}
+
+	private void addEdgeColSizes(GridLocationMap<V, E> gridMap, EdgeSegmentMap<E> segmentMap) {
+		for (ColSegmentList<E> colSegments : segmentMap.colSegments()) {
+			int col = colSegments.getCol();
+			int edgesToLeft = -colSegments.getMinOffset();
+			int edgesToRight = colSegments.getMaxOffset();
+			addColumnEdgeWidth(col, edgesToLeft * edgeSpacing, edgesToRight * edgeSpacing);
+		}
+	}
+
+	private void addEdgeRowSizes(GridLocationMap<V, E> gridMap, EdgeSegmentMap<E> segmentMap) {
+		// edge rows have no vertices, so its height just depends on the number of parallel edges
+		for (RowSegmentList<E> rowSegments : segmentMap.rowSegments()) {
+			int row = rowSegments.getRow();
+			int edgeCount = rowSegments.getMaxOffset() - rowSegments.getMinOffset();
+			addRowHeight(row, edgeCount * edgeSpacing);
+		}
+	}
+
+	private void addVertexSizes(GridLocationMap<V, E> gridMap, Function<V, Shape> transformer) {
+		Map<V, GridPoint> vertexPoints = gridMap.getVertexPoints();
+
+		for (Entry<V, GridPoint> entry : vertexPoints.entrySet()) {
+			V v = entry.getKey();
+			GridPoint p = entry.getValue();
+			Shape shape = transformer.apply(v);
+			Rectangle vertexBounds = shape.getBounds();
+			addRowHeight(p.row, vertexBounds.height);
+			addColumnVertexWidth(p.col, vertexBounds.width);
+		}
+	}
+
+	private void addRowHeight(int row, int height) {
+		rowHeights[row] = Math.max(rowHeights[row], height);
+	}
+
+	private void addColumnVertexWidth(int col, int width) {
+		colVertexWidths[col] = Math.max(colVertexWidths[col], width);
+	}
+
+	private void addColumnEdgeWidth(int col, int beforeWidth, int afterWidth) {
+		beforeColEdgeWidths[col] = Math.max(beforeColEdgeWidths[col], beforeWidth);
+		afterColEdgeWidths[col] = Math.max(afterColEdgeWidths[col], afterWidth);
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/OrthogonalGridToLayoutMapper.java

@@ -0,0 +1,165 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.awt.Rectangle;
+import java.awt.Shape;
+import java.awt.geom.Point2D;
+import java.util.*;
+import java.util.Map.Entry;
+import java.util.function.Function;
+
+import ghidra.graph.viewer.VisualEdge;
+import ghidra.graph.viewer.VisualVertex;
+import ghidra.graph.viewer.layout.*;
+
+/**
+ * Maps the grid points of vertices and edges in a {@link GridLocationMap} to x,y locations in
+ * layout space. The mapping is specifically for grids that contain edges that have been given
+ * orthogonally routed articulation points.
+ * <P>  
+ * First the edges have to be organized into row and column segments so that overlapping segments
+ * can be assigned offsets from the grid lines so that they won't overlap in layout space. Also,
+ * the offset information is need to provide "thickness" for the edges in a row or column.
+ * Next, the grid size and positioning in layout space is computed. Finally, it is a simple matter
+ * to translate grid points for vertices directly into points in layout space. Edge points are
+ * similar, but they need to add their assigned offset for each segment to its corresponding
+ * translated grid articulation point. 
+ *
+ * @param <V> the vertex type
+ * @param <E> the edge type
+ */
+public class OrthogonalGridToLayoutMapper<V extends VisualVertex, E extends VisualEdge<V>> {
+	private static final int EDGE_SPACING = 7;
+	private static final int CONDENSED_EDGE_SPACING = 5;
+
+	private EdgeSegmentMap<E> segmentMap;
+	private GridLocationMap<V, E> grid;
+	private Function<V, Shape> transformer;
+	private GridCoordinates gridCoordinates;
+	private int edgeSpacing;
+
+	public OrthogonalGridToLayoutMapper(GridLocationMap<V, E> grid, Function<V, Shape> transformer,
+			boolean isCondensed) {
+		this.grid = grid;
+		this.transformer = transformer;
+		this.edgeSpacing = isCondensed ? CONDENSED_EDGE_SPACING : EDGE_SPACING;
+
+		// organize the edge articulations into segments by row and column 
+		segmentMap = new EdgeSegmentMap<E>(grid);
+
+		// compute row and column sizes
+		OrthogonalGridSizer<V, E> sizer =
+			new OrthogonalGridSizer<>(grid, segmentMap, transformer, edgeSpacing);
+
+		// get the grid coordinates from the sizer.
+		gridCoordinates = sizer.getGridCoordinates(isCondensed);
+	}
+
+	/**
+	 * Returns a map of vertices to points in layout space.
+	 * @return a map of vertices to points in layout space
+	 */
+	public Map<V, Point2D> getVertexLocations() {
+
+		Map<V, Point2D> vertexLocations = new HashMap<>();
+
+		for (Entry<V, GridPoint> entry : grid.getVertexPoints().entrySet()) {
+			V v = entry.getKey();
+			GridPoint p = entry.getValue();
+
+			Shape shape = transformer.apply(v);
+			Rectangle vertexBounds = shape.getBounds();
+			int x = gridCoordinates.x(p.col);
+			int y = gridCoordinates.y(p.row) + (vertexBounds.height >> 1);
+
+			Point2D location = new Point2D.Double(x, y);
+			vertexLocations.put(v, location);
+		}
+		return vertexLocations;
+	}
+
+	/**
+	 * Returns a map of edges to lists of articulation points in layout space.
+	 * @param vertexLocations the locations of vertices already mapped in layout space.
+	 * @return  a map of edges to lists of articulation points in layout space
+	 */
+	public Map<E, List<Point2D>> getEdgeLocations(Map<V, Point2D> vertexLocations) {
+		Map<E, List<Point2D>> edgeLocations = new HashMap<>();
+		for (E edge : grid.edges()) {
+
+			List<GridPoint> gridPoints = grid.getArticulations(edge);
+			List<Point2D> points = new ArrayList<>(gridPoints.size());
+
+			GridPoint gp = gridPoints.get(0);
+			EdgeSegment<E> edgeSegment = segmentMap.getColumnSegment(edge, gp);
+
+			int offset = edgeSegment.getOffset();
+			double x = gridCoordinates.x(gp.col) + offset * edgeSpacing;
+			double y = vertexLocations.get(edge.getStart()).getY();
+			points.add(new Point2D.Double(x, y));
+
+			for (int i = 1; i < gridPoints.size() - 1; i++) {
+				edgeSegment = edgeSegment.nextSegment();
+				gp = gridPoints.get(i);
+				if (i % 2 == 0) {
+					offset = edgeSegment.getOffset();
+					x = gridCoordinates.x(gp.col) + offset * edgeSpacing;
+					points.add(new Point2D.Double(x, y));
+
+				}
+				else {
+					offset = edgeSegment.getOffset();
+					y = gridCoordinates.y(gp.row) + offset * edgeSpacing;
+					points.add(new Point2D.Double(x, y));
+				}
+			}
+			gp = gridPoints.get(gridPoints.size() - 1);
+			y = vertexLocations.get(edge.getEnd()).getY();
+			points.add(new Point2D.Double(x, y));
+			edgeLocations.put(edge, points);
+		}
+
+		return edgeLocations;
+	}
+
+	/**
+	 * Returns the computed grid coordinates.
+	 * @return the computed grid coordinates
+	 */
+	public GridCoordinates getGridCoordinates() {
+		return gridCoordinates;
+	}
+
+	public List<Integer> getEdgeOffsets(E edge) {
+		List<Integer> offsets = new ArrayList<>();
+		List<GridPoint> gridPoints = grid.getArticulations(edge);
+
+		GridPoint gp = gridPoints.get(0);
+		EdgeSegment<E> edgeSegment = segmentMap.getColumnSegment(edge, gp);
+		while (edgeSegment != null) {
+			offsets.add(edgeSegment.getOffset());
+			edgeSegment = edgeSegment.nextSegment();
+		}
+		return offsets;
+	}
+
+	public void dispose() {
+		segmentMap.dispose();
+		grid.dispose();
+		gridCoordinates = null;
+	}
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/RowSegment.java

@@ -0,0 +1,267 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.List;
+
+import ghidra.graph.viewer.layout.GridPoint;
+
+/**
+ * Horizontal edge segments of an edge with articulation points. Each pair of points in the list
+ * of articulation points corresponds to either a column segment or a row segment. There is
+ * a built-in assumption in the compareTo algorithm that the list of articulation points always
+ * start and end with a column segment. See {@link EdgeSegment} for more information.
+ *
+ * @param <E> The edge type
+ */
+public class RowSegment<E> extends EdgeSegment<E> implements Comparable<RowSegment<E>> {
+	// specifies the orientation of the column attached to this segment (either left or right)
+	enum ColumnOrientation {
+		UP,		// the attached column extends upwards from this row		 
+		DOWN	// the attached column extends downwards from this row
+	}
+
+	private ColumnSegment<E> next;
+	private ColumnSegment<E> previous;
+
+	RowSegment(ColumnSegment<E> previous, E e, List<GridPoint> points, int pointIndex) {
+		super(e, points, pointIndex);
+		this.previous = previous;
+		// row segments always have a follow-on column segment
+		this.next = new ColumnSegment<E>(this, e, points, pointIndex + 1);
+	}
+
+	/**
+	 * Returns the grid row index this row segment.
+	 * @return the grid row index this row segment
+	 */
+	public int getRow() {
+		return points.get(pointIndex).row;
+	}
+
+	/**
+	 * Return the index of the column where this row segment starts. Note that this is different
+	 * from the left column. The start column is in the order of the articulation points whereas 
+	 * the left column is always the left most spatially column (lower column index) of either the
+	 * start column or end column.
+	 * @return the index of the grid column for the start point of this segment
+	 */
+	public int getStartCol() {
+		return points.get(pointIndex).col;
+	}
+
+	/**
+	 * Return the index of the column where this row segment ends. Note that this is different
+	 * from the right column. The end column is in the order of the articulation points whereas 
+	 * the right column is always the right most spatially column (higher column index) of either
+	 * the start column or end column.
+	 * @return the index of the grid column for the start point of this segment
+	 */
+	public int getEndCol() {
+		return points.get(pointIndex + 1).col;
+	}
+
+	/**
+	 * Returns the column index of the left most column of this row segment.
+	 * @return the column index of the left most column of this row segment
+	 */
+	public int getLeftCol() {
+		return Math.min(getStartCol(), getEndCol());
+	}
+
+	/**
+	 * Returns the column index of the right most column of this row segment.
+	 * @return the column index of the right most column of this row segment
+	 */
+	public int getRightCol() {
+		return Math.max(getStartCol(), getEndCol());
+	}
+
+	@Override
+	public int compareTo(RowSegment<E> other) {
+		int result = compareLefts(other);
+		if (result == 0) {
+			result = compareRights(other);
+		}
+		return result;
+	}
+
+	/**
+	 * Checks if the given row segment overlaps horizontally.
+	 * @param other the other column segment to compare
+	 * @return true if these would overlap if drawn with same y row coordinate 
+	 */
+	public boolean overlaps(RowSegment<E> other) {
+		if (getLeftCol() > other.getRightCol()) {
+			return false;
+		}
+		if (getRightCol() < other.getLeftCol()) {
+			return false;
+		}
+		// if the rows are exactly adjacent and if where they touch they are both attached
+		// to terminal column segments, then don't consider them to overlap.
+		if (getLeftCol() == other.getRightCol()) {
+			return !(isLeftTerminal() && other.isRightTerminal());
+		}
+		else if (getRightCol() == other.getLeftCol()) {
+			return !(isRightTerminal() && other.isLeftTerminal());
+		}
+
+		return true;
+	}
+
+	/**
+	 * Compares row segments strictly based  on the relationship of the connected column segments 
+	 * at the left of these segments. 
+	 * @param other the other row segment to compare
+	 * @return  a negative integer, zero, or a positive integer as this object
+	 *          is less than, equal to, or greater than the specified object.
+	 */
+	public int compareLefts(RowSegment<E> other) {
+		// first, just check the rows of this segment and the other, if the rows are
+		// not the same, then one column clearly above the other.
+
+		int result = getRow() - other.getRow();
+		if (result != 0) {
+			return result;
+		}
+
+		// We are in the same grid row, so the order is determined by the segment at the
+		// left of the column. There are 2 possible orientations for the left column. 1) it can
+		// extend upwards from our row, or it can extend downwards from our row.
+		// If our left orientation is not the same as the other row segment, the order is
+		// simply UP < DOWN in order to reduce edge crossings. Edges on the top
+		// go up and edges on the bottom go down, so they won't cross each other.
+		ColumnOrientation myLeftColOrientation = getOrientationForLeftColumn();
+		ColumnOrientation otherLeftColOrientation = other.getOrientationForLeftColumn();
+
+		// if they are not the same, then UP < DOWN
+		if (myLeftColOrientation != otherLeftColOrientation) {
+			return myLeftColOrientation.compareTo(otherLeftColOrientation);
+		}
+
+		// Both this segment's left and the other segment's left have the same orientation. 
+		// Compare the left column segments and use those results to determine our ordering 
+		// top to bottom. If the left columns extend upward, then which ever column is left most 
+		// (lower value), should have it's associated row lower spatially (higher row value)
+		// Keeping left most columns(lower value) as lower rows allows their shape to avoid being
+		// crossed by the wider shape, which will be lower.
+		// 
+		// And if the left rows extends downwards, the inverse applies.	
+		ColumnSegment<E> myLeftColSegment = getLeftColSegment();
+		ColumnSegment<E> otherLeftColSegment = other.getLeftColSegment();
+
+		if (myLeftColOrientation == ColumnOrientation.UP) {
+			return -myLeftColSegment.compareTops(otherLeftColSegment);
+		}
+		return myLeftColSegment.compareBottoms(otherLeftColSegment);
+	}
+
+	/**
+	 * Compares row segments strictly based  on the relationship of the connected column segments 
+	 * at the right of these segments. 
+	 * @param other the other row segment to compare
+	 * @return  a negative integer, zero, or a positive integer as this object
+	 *          is less than, equal to, or greater than the specified object.
+	 */
+	public int compareRights(RowSegment<E> other) {
+		// first, just check the rows of this segment and the other, if the rows are
+		// not the same, then one column clearly above the other.
+		int result = getRow() - other.getRow();
+		if (result != 0) {
+			return result;
+		}
+
+		// We are in the same grid row, so the order is determined by the segment at the
+		// right of the column. There are 2 possible orientations for the right column. 1) it can
+		// extend upwards from our row, or it can extend downwards from our row.
+		// If our right orientation is not the same as the other row segment, the order is
+		// simply UP < DOWN in order to reduce edge crossings. Edges on the top
+		// go up and edges on the bottom go down, so they won't cross each other.
+
+		ColumnOrientation myRightColOrientation = getOrientationForRightColumn();
+		ColumnOrientation otherRightColOrientation = other.getOrientationForRightColumn();
+
+		// if they are not the same, then UP < DOWN
+		if (myRightColOrientation != otherRightColOrientation) {
+			return myRightColOrientation.compareTo(otherRightColOrientation);
+		}
+
+		// Both this segment's right column and the other segment's right column have the same
+		// orientation. Compare the right column segments and use those results to determine our
+		// ordering top to bottom. If the right columns extend upward, then which ever column is
+		// left most (lower value), should have it's associated row higher spatially (lower row
+		// value). Keeping left most columns(lower value) as higher rows (lower values) allows
+		// their shape to avoid being crossed by the wider shape, which will be lower.
+		// 
+		// And if the right rows extends downwards, the inverse applies.	
+		ColumnSegment<E> myRightColSegment = getRightColSegment();
+		ColumnSegment<E> otherRightColSegment = other.getRightColSegment();
+
+		if (myRightColOrientation == ColumnOrientation.UP) {
+			return myRightColSegment.compareTops(otherRightColSegment);
+		}
+		return -myRightColSegment.compareBottoms(otherRightColSegment);
+	}
+
+	@Override
+	public ColumnSegment<E> nextSegment() {
+		return next;
+	}
+
+	@Override
+	public ColumnSegment<E> previousSegment() {
+		return previous;
+	}
+
+	private ColumnOrientation getOrientationForLeftColumn() {
+		ColumnSegment<E> leftSegment = getLeftColSegment();
+		int leftColOtherRow = flowsLeft() ? leftSegment.getEndRow() : leftSegment.getStartRow();
+		return leftColOtherRow < getRow() ? ColumnOrientation.UP : ColumnOrientation.DOWN;
+	}
+
+	private ColumnOrientation getOrientationForRightColumn() {
+		ColumnSegment<E> rightSegment = getRightColSegment();
+		int rightColOtherRow = flowsLeft() ? rightSegment.getStartRow() : rightSegment.getEndRow();
+		return rightColOtherRow < getRow() ? ColumnOrientation.UP : ColumnOrientation.DOWN;
+	}
+
+	private ColumnSegment<E> getLeftColSegment() {
+		return flowsLeft() ? next : previous;
+	}
+
+	private ColumnSegment<E> getRightColSegment() {
+		return flowsLeft() ? previous : next;
+	}
+
+	private boolean flowsLeft() {
+		return getStartCol() > getEndCol();
+	}
+
+	private boolean isLeftTerminal() {
+		ColumnSegment<E> left = getLeftColSegment();
+		return left.isStartSegment() || left.isEndSegment();
+	}
+
+	private boolean isRightTerminal() {
+		ColumnSegment<E> right = getRightColSegment();
+		return right.isStartSegment() || right.isEndSegment();
+	}
+
+	public ColumnSegment<E> last() {
+		return next.last();
+	}
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/RowSegmentList.java

@@ -0,0 +1,116 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import java.util.*;
+
+import org.apache.commons.collections4.map.LazyMap;
+
+/**
+ * Maintains a collection of RowSegments for the same grid row. 
+ *
+ * @param <E> edge type
+ */
+public class RowSegmentList<E> {
+	protected List<RowSegment<E>> edgeSegments = new ArrayList<>();
+	int row;
+
+	public RowSegmentList(int row) {
+		this.row = row;
+	}
+
+	protected void addSegment(RowSegment<E> segment) {
+		edgeSegments.add(segment);
+	}
+
+	@Override
+	public String toString() {
+		return edgeSegments.toString();
+	}
+
+	public int getRow() {
+		return row;
+	}
+
+	/**
+	 * Returns the minimum offset of any edges in this segment list.
+	 * @return the minimum offset of any edges in this segment list
+	 */
+	public int getMinOffset() {
+		int minOffset = 0;
+		for (EdgeSegment<E> edgeSegment : edgeSegments) {
+			minOffset = Math.min(minOffset, edgeSegment.getOffset());
+		}
+		return minOffset;
+	}
+
+	/**
+	 * Returns the maximum offset of any edges in this segment list.
+	 * @return the maximum offset of any edges in this segment list
+	 */
+	public int getMaxOffset() {
+		int maxOffset = 0;
+		for (EdgeSegment<E> edgeSegment : edgeSegments) {
+			maxOffset = Math.max(maxOffset, edgeSegment.getOffset());
+		}
+		return maxOffset;
+	}
+
+	/**
+	 * Assigns offsets for overlapping row segments. Parallel overlapping edges must be offset
+	 * from each other when assigned to layout space to avoid drawing over each other. Each
+	 * edge offset represents 1/2 the edge spacing distance. The reason offsets are assigned 2
+	 * apart from each other is to be consistent with column segment offsets which must be 2 apart
+	 * so that even numbers of edges can be centered on the grid line.
+	 */
+	public void assignOffsets() {
+		// sorts the row edge segments from top to bottom
+		Collections.sort(edgeSegments);
+
+		Map<Integer, RowSegmentList<E>> offsetMap =
+			LazyMap.lazyMap(new HashMap<>(), k -> new RowSegmentList<E>(0));
+		for (int i = 0; i < edgeSegments.size(); i++) {
+			RowSegment<E> segment = edgeSegments.get(i);
+			assignOffset(offsetMap, segment);
+		}
+	}
+
+	protected void assignOffset(Map<Integer, RowSegmentList<E>> offsetMap, RowSegment<E> segment) {
+
+		// assigning offsets to rows is easy, just find the first offset group that we don't
+		// overlap with.
+
+		int offset = 0;
+		RowSegmentList<E> segments = offsetMap.get(offset);
+
+		while (segments.hasOverlappingSegment(segment)) {
+			offset += 2;
+			segments = offsetMap.get(offset);
+		}
+		segment.setOffset(offset);
+		segments.addSegment(segment);
+	}
+
+	private boolean hasOverlappingSegment(RowSegment<E> segment) {
+		for (RowSegment<E> edgeSegment : edgeSegments) {
+			if (segment.overlaps(edgeSegment)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+}

Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/jungrapht/JgtNamedLayout.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -56,7 +56,7 @@ public class JgtNamedLayout extends AbstractFGLayout {
 	}
 
 	@Override
-	protected Point2D getVertexLocation(FGVertex v, Column col, Row<FGVertex> row,
+	protected Point2D getVertexLocation(FGVertex v, Column<FGVertex> col, Row<FGVertex> row,
 			java.awt.Rectangle bounds) {
 		return getCenteredVertexLocation(v, col, row, bounds);
 	}
@@ -148,14 +148,14 @@ public class JgtNamedLayout extends AbstractFGLayout {
 		for (FGEdge fgEdge : edges) {
 			monitor.checkCancelled();
 
-			List<java.awt.Point> newPoints = new ArrayList<>();
+			List<GridPoint> newPoints = new ArrayList<>();
 
 			List<Point> articulations = articulator.apply(fgEdge);
 			for (Point point : articulations) {
 
 				Integer col = columns.get(point.x);
 				Integer row = rows.get(point.y);
-				newPoints.add(new java.awt.Point(col, row));
+				newPoints.add(new GridPoint(row, col));
 			}
 
 			// The jung layout will provide articulations at the vertex points.   We do not want to

Ghidra/Features/FunctionGraph/src/main/java/ghidra/graph/viewer/FGViewUpdater.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -627,10 +627,13 @@ public class FGViewUpdater extends VisualGraphViewUpdater<FGVertex, FGEdge> {
 			parentVertex.setVertexType(oldVertexType);
 			childVertex.setVertexType(oldVertexType);
 		}
-
 		graph.addVertex(parentVertex);
 		graph.addVertex(childVertex);
 
+		FunctionGraph fg = (FunctionGraph) graph;
+		if (vertexToSplit == fg.getRootVertex()) {
+			fg.setRootVertex(parentVertex);
+		}
 		//
 		// Second: add the edges from the original vertices to the new vertices
 		//

Ghidra/Features/FunctionGraph/src/test.slow/java/ghidra/app/plugin/core/functiongraph/graph/layout/TestFGLayoutProvider.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -77,7 +77,7 @@ public class TestFGLayoutProvider extends FGLayoutProvider {
 		}
 
 		@Override
-		protected Point2D getVertexLocation(FGVertex v, Column col, Row<FGVertex> row,
+		protected Point2D getVertexLocation(FGVertex v, Column<FGVertex> col, Row<FGVertex> row,
 				Rectangle bounds) {
 			return getCenteredVertexLocation(v, col, row, bounds);
 		}
@@ -257,8 +257,8 @@ public class TestFGLayoutProvider extends FGLayoutProvider {
 				// -->Maybe positioning is simple enough?
 				//
 
-				Column startCol = layoutLocations.col(startVertex);
-				Column endCol = layoutLocations.col(endVertex);
+				Column<FGVertex> startCol = layoutLocations.col(startVertex);
+				Column<FGVertex> endCol = layoutLocations.col(endVertex);
 				Point2D start = vertexLayoutLocations.get(startVertex);
 				Point2D end = vertexLayoutLocations.get(endVertex);
 				List<Point2D> articulations = new ArrayList<>();

Ghidra/Features/FunctionGraph/src/test.slow/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/AbstractFlowChartLayoutTest.java

@@ -0,0 +1,420 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import static org.junit.Assert.*;
+
+import java.awt.*;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.function.Function;
+
+import javax.swing.JFrame;
+
+import org.junit.Before;
+
+import docking.test.AbstractDockingTest;
+import ghidra.graph.VisualGraph;
+import ghidra.graph.graphs.*;
+import ghidra.graph.support.TestVisualGraph;
+import ghidra.graph.viewer.GraphComponent;
+import ghidra.graph.viewer.layout.*;
+import ghidra.util.*;
+import ghidra.util.exception.CancelledException;
+
+abstract public class AbstractFlowChartLayoutTest extends AbstractDockingTest {
+	protected TestVisualGraph g;
+	protected GridLocationMap<AbstractTestVertex, TestEdge> grid;
+	protected OrthogonalGridToLayoutMapper<AbstractTestVertex, TestEdge> layoutMap;
+	private boolean alignLeft;
+
+	protected LabelTestVertex A = v('A');
+	protected LabelTestVertex B = v('B');
+	protected LabelTestVertex C = v('C');
+	protected LabelTestVertex D = v('D');
+	protected LabelTestVertex E = v('E');
+	protected LabelTestVertex F = v('F');
+	protected LabelTestVertex G = v('G');
+	protected LabelTestVertex H = v('H');
+	protected LabelTestVertex I = v('I');
+	protected LabelTestVertex J = v('J');
+	protected LabelTestVertex K = v('K');
+
+	protected AbstractFlowChartLayoutTest(boolean alignLeft) {
+		this.alignLeft = alignLeft;
+	}
+
+	@Before
+	public void setUp() {
+		g = new TestVisualGraph();
+	}
+
+	protected void showGraph() {
+
+		Swing.runNow(() -> {
+			JFrame frame = new JFrame("Graph Viewer Test");
+
+			TestFlowChartLayout layout = new TestFlowChartLayout(g, A, alignLeft);
+			g.setLayout(layout);
+			GraphComponent<AbstractTestVertex, TestEdge, TestVisualGraph> graphComponent =
+				new GraphComponent<>(g);
+			graphComponent.setSatelliteVisible(false);
+
+			frame.setSize(new Dimension(800, 800));
+			frame.setLocation(2400, 100);
+			frame.getContentPane().add(graphComponent.getComponent());
+			frame.setVisible(true);
+			frame.validate();
+		});
+	}
+
+	protected void assertEdge(EdgeVerifier edgeVerifier) {
+		edgeVerifier.checkEdge();
+	}
+
+	protected void assertVertices(String expected) {
+		String actual = generateCompactGridVertexString();
+		if (!expected.equals(actual)) {
+			reportGridError(expected, actual);
+		}
+	}
+
+	private void reportGridError(String expectedString, String actualString) {
+		String[] actual = StringUtilities.toLines(actualString, false);
+		String[] expected = StringUtilities.toLines(expectedString, false);
+		assertEquals("Number of rows don't match! ", expected.length, actual.length);
+		checkCols(expected);
+		assertEquals("Number of columns don't match! ", expected[0].length(), actual[0].length());
+
+		if (!expectedString.equals(actualString)) {
+			printGridsToConsole(actual, expected);
+			int firstRowDiff = findFirstRowDiff(actual, expected);
+			int firstColDiff = findFirstColDiff(actual[firstRowDiff], expected[firstRowDiff]);
+			fail("Graphs don't match! First diff is at row " + firstRowDiff + ", col " +
+				firstColDiff + ". See console for details.");
+		}
+
+	}
+
+	private int findFirstColDiff(String string1, String string2) {
+		for (int i = 0; i < string1.length(); i++) {
+			if (string1.charAt(i) != string2.charAt(i)) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	private int findFirstRowDiff(String[] actual, String[] expected) {
+		for (int i = 0; i < actual.length; i++) {
+			if (!actual[i].equals(expected[i])) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	private void printGridsToConsole(String[] actual, String[] expected) {
+		StringWriter writer = new StringWriter();
+		PrintWriter out = new PrintWriter(writer);
+		out.println("Graphs don't match!\n");
+		String expectedLabel = "Expected: ";
+		String actualLabel = "  Actual: ";
+		String diffLabel = "   Diffs: ";
+		String[] diffs = computeDiffs(actual, expected);
+		for (int row = 0; row < expected.length; row++) {
+			out.print(expectedLabel);
+			out.print(expected[row]);
+			out.print(actualLabel);
+			out.print(actual[row]);
+			out.print(diffLabel);
+			out.println(diffs[row]);
+			expectedLabel = "          ";
+			actualLabel = expectedLabel;
+			diffLabel = expectedLabel;
+		}
+		Msg.error(this, writer.toString());
+	}
+
+	private String[] computeDiffs(String[] actual, String[] expected) {
+		String[] diffs = new String[actual.length];
+		for (int i = 0; i < diffs.length; i++) {
+			diffs[i] = computeDiffString(actual[i], expected[i]);
+		}
+		return diffs;
+	}
+
+	private String computeDiffString(String string1, String string2) {
+		StringBuilder buf = new StringBuilder();
+		for (int i = 0; i < string1.length(); i++) {
+			char c = string1.charAt(i) == string2.charAt(i) ? '.' : 'x';
+			buf.append(c);
+		}
+		return buf.toString();
+	}
+
+	private void checkCols(String[] expected) {
+		int len = expected[0].length();
+		for (String line : expected) {
+			if (line.length() != len) {
+				fail("Invalid graph grid specified in test. Lines vary in length!");
+			}
+		}
+	}
+
+	private String generateCompactGridEdgeString(TestEdge e, List<GridPoint> points) {
+		char[][] gridChars = createEmptyGridChars();
+		fillGridCharColumn(gridChars, points.get(0), points.get(1));
+
+		for (int i = 1; i < points.size() - 2; i++) {
+			fillGridCharRow(gridChars, points.get(i), points.get(i + 1));
+			fillGridCharColumn(gridChars, points.get(i + 1), points.get(i + 2));
+		}
+
+		AbstractTestVertex start = e.getStart();
+		AbstractTestVertex end = e.getEnd();
+		GridPoint startPoint = grid.gridPoint(start);
+		GridPoint endPoint = grid.gridPoint(end);
+		gridChars[startPoint.row][startPoint.col] = start.toString().charAt(0);
+		gridChars[endPoint.row][endPoint.col] = end.toString().charAt(0);
+
+		return toString(gridChars);
+	}
+
+	private void fillGridCharRow(char[][] gridChars, GridPoint p1, GridPoint p2) {
+		int row = p1.row;
+		int startCol = Math.min(p1.col, p2.col);
+		int endCol = Math.max(p1.col, p2.col);
+		for (int col = startCol; col <= endCol; col++) {
+			gridChars[row][col] = '*';
+		}
+	}
+
+	private void fillGridCharColumn(char[][] gridChars, GridPoint p1, GridPoint p2) {
+		int col = p1.col;
+		int startRow = Math.min(p1.row, p2.row);
+		int endRow = Math.max(p1.row, p2.row);
+		for (int row = startRow; row <= endRow; row++) {
+			gridChars[row][col] = '*';
+		}
+	}
+
+	private String generateCompactGridVertexString() {
+		char[][] gridChars = createEmptyGridChars();
+
+		for (Entry<AbstractTestVertex, GridPoint> entry : grid.getVertexPoints().entrySet()) {
+			char id = entry.getKey().toString().charAt(0);
+			GridPoint point = entry.getValue();
+			gridChars[point.row][point.col] = id;
+		}
+
+		return toString(gridChars);
+	}
+
+	private String toString(char[][] gridChars) {
+		StringBuilder buf = new StringBuilder();
+		for (int row = 0; row < grid.height(); row++) {
+			for (int col = 0; col < grid.width(); col++) {
+				buf.append(gridChars[row][col]);
+			}
+			buf.append("\n");
+		}
+		return buf.toString();
+	}
+
+	private char[][] createEmptyGridChars() {
+		int rows = grid.height();
+		int cols = grid.width();
+		char[][] gridChars = new char[rows][cols];
+		for (int row = 0; row < rows; row++) {
+			for (int col = 0; col < cols; col++) {
+				gridChars[row][col] = '.';
+			}
+		}
+		return gridChars;
+	}
+
+	protected EdgeVerifier e(LabelTestVertex start, LabelTestVertex end) {
+		return new EdgeVerifier(start, end);
+	}
+
+	protected class EdgeVerifier {
+
+		private TestEdge edge;
+		private List<GridPoint> expectedPoints = new ArrayList<>();
+		private List<Integer> expectedOffsets = new ArrayList<>();
+
+		public EdgeVerifier(LabelTestVertex start, LabelTestVertex end) {
+			this.edge = new TestEdge(start, end);
+			expectedPoints.add(grid.gridPoint(start));
+		}
+
+		public EdgeVerifier colSegment(int rows, int offset) {
+			GridPoint lastPoint = expectedPoints.get(expectedPoints.size() - 1);
+			GridPoint p = new GridPoint(lastPoint.row + rows, lastPoint.col);
+			if (!grid.containsPoint(p)) {
+				fail("Bad column specification. Row movement of " + rows + " exceeds grid size!");
+			}
+			expectedPoints.add(p);
+			expectedOffsets.add(offset);
+			return this;
+		}
+
+		public EdgeVerifier rowSegment(int cols, int offset) {
+			GridPoint lastPoint = expectedPoints.get(expectedPoints.size() - 1);
+			GridPoint p = new GridPoint(lastPoint.row, lastPoint.col + cols);
+			if (!grid.containsPoint(p)) {
+				fail("Bad row specification. Column movement of " + cols + " exceeds grid size!");
+			}
+			expectedPoints.add(p);
+			expectedOffsets.add(offset);
+			return this;
+		}
+
+		public void checkEdge() {
+			List<GridPoint> actual = grid.getArticulations(edge);
+			if (expectedPoints.size() < 2) {
+				fail("Specified Edge for edge " + edge + " is missing segment specifications!");
+			}
+
+			if (actual.isEmpty()) {
+				fail("Expected edge articulations for " + edge + "not found!");
+			}
+
+			if (!actual.equals(expectedPoints)) {
+
+				printEdgeDiffs(actual);
+				fail("Articulations for edge " + edge + " don't match! See console for details");
+			}
+
+			List<Integer> actualOffsets = layoutMap.getEdgeOffsets(edge);
+			for (int i = 0; i < expectedOffsets.size(); i++) {
+				GridPoint p1 = expectedPoints.get(i);
+				GridPoint p2 = expectedPoints.get(i + 1);
+				assertEquals(
+					"Edge Offsets differ for edge " + edge + " at segment " + i +
+						", from " + p1 + " to " + p2 + "! ",
+					expectedOffsets.get(i), actualOffsets.get(i));
+			}
+		}
+
+		private void printEdgeDiffs(List<GridPoint> actualPoints) {
+			StringWriter writer = new StringWriter();
+			PrintWriter out = new PrintWriter(writer);
+			String expectedString = generateCompactGridEdgeString(edge, expectedPoints);
+			String actualString = generateCompactGridEdgeString(edge, actualPoints);
+			String[] expected = StringUtilities.toLines(expectedString, false);
+			String[] actual = StringUtilities.toLines(actualString, false);
+
+			out.println("Edge articulations don't match for " + edge.toString() + "!\n");
+			String expectedLabel = "Expected: ";
+			String actualLabel = "  Actual: ";
+			for (int row = 0; row < expected.length; row++) {
+				out.print(expectedLabel);
+				out.print(expected[row]);
+				out.print(actualLabel);
+				out.println(actual[row]);
+				expectedLabel = "          ";
+				actualLabel = expectedLabel;
+
+			}
+			Msg.error(this, writer.toString());
+		}
+	}
+
+	protected int offset(int i) {
+		return i;
+	}
+
+	protected int down(int i) {
+		return i;
+	}
+
+	protected int up(int i) {
+		return -i;
+	}
+
+	protected int left(int i) {
+		return -i;
+	}
+
+	protected int right(int i) {
+		return i;
+	}
+
+	protected void applyLayout() throws CancelledException {
+		TestFlowChartLayout layout = new TestFlowChartLayout(g, A, alignLeft);
+		grid = layout.performInitialGridLayout(g);
+		Function<AbstractTestVertex, Shape> transformer = v -> new Rectangle(0, 0, 50, 50);
+		layoutMap =
+			new OrthogonalGridToLayoutMapper<AbstractTestVertex, TestEdge>(grid, transformer, true);
+	}
+
+	// a shortcut for edge(v(startId), v(endId)), for readability
+	protected TestEdge edge(LabelTestVertex v1, LabelTestVertex v2) {
+		TestEdge testEdge = new TestEdge(v1, v2);
+		g.addEdge(testEdge);
+		return testEdge;
+	}
+
+	protected LabelTestVertex v(char id) {
+		return new LabelTestVertex("" + id);
+	}
+
+	private static class TestFlowChartLayout
+			extends AbstractFlowChartLayout<AbstractTestVertex, TestEdge> {
+
+		private AbstractTestVertex root;
+
+		protected TestFlowChartLayout(DefaultVisualGraph<AbstractTestVertex, TestEdge> graph,
+				AbstractTestVertex root, boolean leftAlign) {
+			super(graph, new TestEdgeComparator(), leftAlign);
+			this.root = root;
+		}
+
+		@Override
+		public AbstractVisualGraphLayout<AbstractTestVertex, TestEdge> createClonedLayout(
+				VisualGraph<AbstractTestVertex, TestEdge> newGraph) {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		protected AbstractTestVertex getRoot(VisualGraph<AbstractTestVertex, TestEdge> g) {
+			return root;
+		}
+
+		@Override
+		protected GridLocationMap<AbstractTestVertex, TestEdge> performInitialGridLayout(
+				VisualGraph<AbstractTestVertex, TestEdge> g) throws CancelledException {
+
+			return super.performInitialGridLayout(g);
+		}
+
+	}
+
+	private static class TestEdgeComparator implements Comparator<TestEdge> {
+
+		@Override
+		public int compare(TestEdge e1, TestEdge e2) {
+			return e1.toString().compareTo(e2.toString());
+		}
+	}
+
+}

Ghidra/Features/FunctionGraph/src/test.slow/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/FlowChartLayoutTest.java

@@ -0,0 +1,264 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import ghidra.graph.support.TestVisualGraph;
+import ghidra.util.exception.CancelledException;
+
+public class FlowChartLayoutTest extends AbstractFlowChartLayoutTest {
+
+	public FlowChartLayoutTest() {
+		super(false);
+	}
+
+	@Override
+	@Before
+	public void setUp() {
+		g = new TestVisualGraph();
+	}
+
+	@Test
+	public void testBasicRootWithTwoChildren() throws CancelledException {
+		edge(A, B);
+		edge(A, C);
+		applyLayout();
+		showGraph();
+
+		assertVertices("""
+				....
+				..A.
+				....
+				.B.C
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(1), offset(-1))
+				.rowSegment(left(1), offset(0))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(A, C)
+				.colSegment(down(1), offset(1))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(1), offset(0)));
+
+	}
+
+	@Test
+	public void testBasicGraphWithThreeChildren() throws CancelledException {
+		edge(A, B);
+		edge(A, C);
+		edge(A, D);
+		applyLayout();
+
+//		showGraph();
+
+		assertVertices("""
+				......
+				...A..
+				......
+				.B.C.D
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(1), offset(-2))
+				.rowSegment(left(2), offset(0))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(A, C)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(A, D)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(0))
+				.colSegment(down(1), offset(0)));
+
+	}
+
+	@Test
+	public void testBasicGraphWithBackEdge() throws CancelledException {
+		edge(A, B);
+		edge(A, C);
+		edge(A, D);
+		edge(D, A);
+		applyLayout();
+
+//		showGraph();
+
+		assertVertices("""
+				.......
+				...A...
+				.......
+				.B.C.D.
+				.......
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(1), offset(-2))
+				.rowSegment(left(2), offset(0))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(A, C)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(A, D)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(0))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(D, A)
+				.colSegment(down(1), offset(0))
+				.rowSegment(right(1), offset(0))
+				.colSegment(up(4), offset(0))
+				.rowSegment(left(3), offset(0))
+				.colSegment(down(1), offset(0)));
+
+	}
+
+	@Test
+	public void testComplexGraph() throws CancelledException {
+
+		//@formatter:off
+		/*
+				  A
+			 	  |
+				  B
+			 	  |
+	sink    C <---D
+		    |	  |
+		   	|	  E
+			| 	//   \
+			|  |F    G
+		    |  ||\   |
+		    |  |H | /
+		    |  | \|/ 
+		    |  |  I
+			|  | / \
+		    |  |/   \
+		    .<-K---->J	sink
+
+		*/
+		//@formatter:on		edge(A, B);
+		edge(A, B);
+		edge(B, D);
+		edge(D, C);
+		edge(D, E);
+
+		edge(E, F);
+		edge(E, G);
+		edge(E, K);
+		edge(F, H);
+		edge(F, I);
+		edge(G, I);
+		edge(H, I);
+		edge(I, J);
+		edge(I, K);
+		edge(K, C);
+		edge(K, J);
+
+		applyLayout();
+
+//		showGraph();
+
+		assertVertices("""
+				.....
+				...A.
+				.....
+				...B.
+				.....
+				...D.
+				.....
+				...E.
+				.....
+				..F.G
+				.....
+				..H..
+				.....
+				..I..
+				.....
+				..K..
+				.....
+				.C.J.
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(B, D)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(D, C)
+				.colSegment(down(1), offset(-2))
+				.rowSegment(left(2), offset(0))
+				.colSegment(down(11), offset(-1)));
+
+		assertEdge(e(D, E)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(E, F)
+				.colSegment(down(1), offset(-1))
+				.rowSegment(left(1), offset(0))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(E, G)
+				.colSegment(down(1), offset(3))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(E, K)
+				.colSegment(down(7), offset(1))
+				.rowSegment(left(1), offset(2))
+				.colSegment(down(1), offset(2)));
+
+		assertEdge(e(F, H)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(F, I)
+				.colSegment(down(1), offset(-2))
+				.rowSegment(left(1), offset(0))
+				.colSegment(down(2), offset(1))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(1), offset(-2)));
+
+		assertEdge(e(G, I)
+				.colSegment(down(3), offset(0))
+				.rowSegment(left(2), offset(0))
+				.colSegment(down(1), offset(2)));
+
+		assertEdge(e(H, I)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(I, J)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(3), offset(-1)));
+		assertEdge(e(I, K)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(K, C)
+				.colSegment(down(1), offset(-1))
+				.rowSegment(left(1), offset(0))
+				.colSegment(down(1), offset(1)));
+
+		assertEdge(e(K, J)
+				.colSegment(down(1), offset(1))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(1), offset(-3)));
+	}
+
+}

Ghidra/Features/FunctionGraph/src/test.slow/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/LeftAlignedFlowChartLayoutTest.java

@@ -0,0 +1,258 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import org.junit.Test;
+
+import ghidra.util.Msg;
+import ghidra.util.exception.CancelledException;
+
+public class LeftAlignedFlowChartLayoutTest extends AbstractFlowChartLayoutTest {
+
+	public LeftAlignedFlowChartLayoutTest() {
+		super(true);
+	}
+
+	@Test
+	public void testBasicRootWithTwoChildren() throws CancelledException {
+		edge(A, B);
+		edge(A, C);
+		applyLayout();
+
+//		showGraph();
+//		Msg.out(grid.toStringGrid());
+
+		assertVertices("""
+				....
+				.A..
+				....
+				.B.C
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(A, C)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(0))
+				.colSegment(down(1), offset(0)));
+
+	}
+
+	@Test
+	public void testBasicGraphWithThreeChildren() throws CancelledException {
+		edge(A, B);
+		edge(A, C);
+		edge(A, D);
+		applyLayout();
+
+//		showGraph();
+		Msg.out(grid.toStringGrid());
+
+		assertVertices("""
+				......
+				.A....
+				......
+				.B.C.D
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(A, C)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(2))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(A, D)
+				.colSegment(down(1), offset(4))
+				.rowSegment(right(4), offset(0))
+				.colSegment(down(1), offset(0)));
+
+	}
+
+	@Test
+	public void testBasicGraphWithBackEdge() throws CancelledException {
+		edge(A, B);
+		edge(A, C);
+		edge(A, D);
+		edge(D, A);
+		applyLayout();
+
+//		showGraph();
+//		Msg.out(grid.toStringGrid());
+
+		assertVertices("""
+				.......
+				.A.....
+				.......
+				.B.C.D.
+				.......
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(A, C)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(2))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(A, D)
+				.colSegment(down(1), offset(4))
+				.rowSegment(right(4), offset(0))
+				.colSegment(down(1), offset(0)));
+		assertEdge(e(D, A)
+				.colSegment(down(1), offset(0))
+				.rowSegment(right(1), offset(0))
+				.colSegment(up(4), offset(0))
+				.rowSegment(left(5), offset(0))
+				.colSegment(down(1), offset(0)));
+	}
+
+	@Test
+	public void testComplexGraph() throws CancelledException {
+
+		//@formatter:off
+		/*
+				  A
+			 	  |
+				  B
+			 	  |
+	sink    C <---D
+		    |	  |
+		   	|	  E
+			| 	//   \
+			|  |F    G
+		    |  ||\   |
+		    |  |H | /
+		    |  | \|/ 
+		    |  |  I
+			|  | / \
+		    |  |/   \
+		    .<-K---->J	sink
+
+		*/
+		//@formatter:on		edge(A, B);
+		edge(A, B);
+		edge(B, D);
+		edge(D, C);
+		edge(D, E);
+
+		edge(E, F);
+		edge(E, G);
+		edge(E, K);
+		edge(F, H);
+		edge(F, I);
+		edge(G, I);
+		edge(H, I);
+		edge(I, J);
+		edge(I, K);
+		edge(K, C);
+		edge(K, J);
+
+		applyLayout();
+
+		showGraph();
+		Msg.out(grid.toStringGrid());
+
+		assertVertices("""
+				....
+				.A..
+				....
+				.B..
+				....
+				.D..
+				....
+				.E..
+				....
+				.F.G
+				....
+				.H..
+				....
+				.I..
+				....
+				.K..
+				....
+				.C.J
+				""");
+
+		assertEdge(e(A, B)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(B, D)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(D, C)
+				.colSegment(down(1), offset(-2))
+				.rowSegment(left(1), offset(0))
+				.colSegment(down(10), offset(-2))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(1), offset(-2)));
+
+		assertEdge(e(D, E)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(E, F)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(E, G)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(0))
+				.colSegment(down(1), offset(0)));
+
+		assertEdge(e(E, K)
+				.colSegment(down(1), offset(-2))
+				.rowSegment(left(1), offset(0))
+				.colSegment(down(6), offset(0))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(1), offset(-2)));
+
+		assertEdge(e(F, H)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(F, I)
+				.colSegment(down(1), offset(-2))
+				.rowSegment(left(1), offset(0))
+				.colSegment(down(2), offset(2))
+				.rowSegment(right(1), offset(0))
+				.colSegment(down(1), offset(-2)));
+
+		assertEdge(e(G, I)
+				.colSegment(down(3), offset(0))
+				.rowSegment(left(2), offset(0))
+				.colSegment(down(1), offset(2)));
+
+		assertEdge(e(H, I)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(I, J)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(0))
+				.colSegment(down(3), offset(1)));
+		assertEdge(e(I, K)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(K, C)
+				.colSegment(down(2), offset(0)));
+
+		assertEdge(e(K, J)
+				.colSegment(down(1), offset(2))
+				.rowSegment(right(2), offset(0))
+				.colSegment(down(1), offset(-1)));
+	}
+
+}

Ghidra/Features/FunctionGraph/src/test/java/ghidra/app/plugin/core/functiongraph/graph/layout/flowchart/EdgeSegmentTest.java

@@ -0,0 +1,982 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.plugin.core.functiongraph.graph.layout.flowchart;
+
+import static org.junit.Assert.*;
+
+import java.util.*;
+
+import org.junit.Test;
+
+import ghidra.graph.graphs.TestEdge;
+import ghidra.graph.graphs.TestVertex;
+import ghidra.graph.viewer.layout.GridPoint;
+
+public class EdgeSegmentTest {
+	private static int DOWN = 1;
+	private static int UP = -1;
+	private static int LEFT = -1;
+	private static int RIGHT = 1;
+	private static int UP_2 = -2;
+	private static int DOWN_2 = 2;
+	private static int LEFT_2 = -2;
+	private static int RIGHT_2 = 2;
+
+	private TestVertex v1 = v(1);
+	private TestVertex v2 = v(2);
+	private TestVertex v3 = v(3);
+	private TestVertex v4 = v(4);
+	private TestEdge e12 = e(v1, v2);
+	private TestEdge e13 = e(v1, v2);
+	private TestEdge e14 = e(v1, v4);
+	private TestEdge e23 = e(v2, v3);
+	private TestEdge e24 = e(v2, v4);
+	private TestEdge e34 = e(v3, v4);
+
+//==================================================================================================
+// The following tests compare starting edge segments.
+//=================================================================================================
+	@Test
+	public void testStartSegmentsInTotallyDifferentColumns() {
+		ColumnSegment<TestEdge> col1 = segment(e12, p(0, 1), DOWN);
+		ColumnSegment<TestEdge> col2 = segment(e13, p(0, 2), DOWN);
+
+		assertLessThan(col1, col2);
+		assertGreaterThan(col2, col1);
+	}
+
+	@Test
+	public void testCompareStartSegmentByDirectionOfBottomRow() {
+		GridPoint p = p(0, 0);
+		ColumnSegment<TestEdge> down = segment(e12, p, DOWN_2);
+		ColumnSegment<TestEdge> left = segment(e13, p, DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> right = segment(e14, p, DOWN, RIGHT, DOWN);
+
+		assertLessThan(left, down);
+		assertGreaterThan(down, left);
+
+		assertLessThan(down, right);
+		assertGreaterThan(right, down);
+
+		assertLessThan(left, right);
+		assertGreaterThan(right, left);
+
+		// test edges are equals to themselves
+		assertEquals(down, down);
+		assertEquals(left, left);
+		assertEquals(right, right);
+	}
+
+	@Test
+	public void testCompareStartBothLeftButDifferentRowLevels() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> down1_left = segment(e13, p, DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> down2_left = segment(e14, p, DOWN_2, LEFT, DOWN);
+
+		assertLessThan(down1_left, down2_left);
+		assertGreaterThan(down2_left, down1_left);
+
+	}
+
+	@Test
+	public void testCompareStartBothRightButDifferentRowLevels() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> down1_right = segment(e13, p, DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> down2_right = segment(e14, p, DOWN_2, RIGHT, DOWN);
+
+		assertLessThan(down2_right, down1_right);
+		assertGreaterThan(down1_right, down2_right);
+
+	}
+
+	@Test
+	public void testCompareStartBothLeftThenOppositeDirection() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> leftUp = segment(e13, p, DOWN, LEFT, UP);
+		ColumnSegment<TestEdge> leftDown = segment(e14, p, DOWN, LEFT, DOWN);
+
+		assertLessThan(leftUp, leftDown);
+		assertGreaterThan(leftDown, leftUp);
+
+	}
+
+	@Test
+	public void testCompareStartBothRightsThenOppositeDirection() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> rightUp = segment(e13, p, DOWN, RIGHT, UP);
+		ColumnSegment<TestEdge> rightDown = segment(e14, p, DOWN, RIGHT, DOWN);
+
+		assertLessThan(rightDown, rightUp);
+		assertGreaterThan(rightUp, rightDown);
+
+	}
+
+	@Test
+	public void testCompareLeftDownButDifferentLeftColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> left1 = segment(e13, p, DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> left2 = segment(e14, p, DOWN, LEFT_2, DOWN);
+
+		assertLessThan(left2, left1);
+		assertGreaterThan(left1, left2);
+	}
+
+	@Test
+	public void testCompareLeftUpButDifferentLeftColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> left1 = segment(e13, p, DOWN, LEFT, UP);
+		ColumnSegment<TestEdge> left2 = segment(e14, p, DOWN, LEFT_2, UP);
+
+		assertLessThan(left1, left2);
+		assertGreaterThan(left2, left1);
+	}
+
+	@Test
+	public void testCompareRightDownButDifferentRightColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> right1 = segment(e13, p, DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> right2 = segment(e14, p, DOWN, RIGHT_2, DOWN);
+
+		assertLessThan(right1, right2);
+		assertGreaterThan(right2, right1);
+	}
+
+	@Test
+	public void testCompareRightUpButDifferentRightColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> right1 = segment(e13, p, DOWN, RIGHT, UP);
+		ColumnSegment<TestEdge> right2 = segment(e14, p, DOWN, RIGHT_2, UP);
+
+		assertLessThan(right2, right1);
+		assertGreaterThan(right1, right2);
+	}
+
+	@Test
+	public void testCompareLeftUpButUpperRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_u_left = segment(e13, p, DOWN, LEFT, UP, LEFT);
+		ColumnSegment<TestEdge> l_u_right = segment(e14, p, DOWN, LEFT, UP, RIGHT);
+
+		assertLessThan(l_u_right, l_u_left);
+		assertGreaterThan(l_u_left, l_u_right);
+	}
+
+	@Test
+	public void testCompareLeftDownButLowerRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_d_left = segment(e13, p, DOWN, LEFT, DOWN, LEFT);
+		ColumnSegment<TestEdge> l_d_right = segment(e14, p, DOWN, LEFT, DOWN, RIGHT);
+
+		assertLessThan(l_d_left, l_d_right);
+		assertGreaterThan(l_d_right, l_d_left);
+	}
+
+	@Test
+	public void testCompareRightUpButUpperRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_u_left = segment(e13, p, DOWN, RIGHT, UP, LEFT);
+		ColumnSegment<TestEdge> r_u_right = segment(e14, p, DOWN, RIGHT, UP, RIGHT);
+
+		assertLessThan(r_u_right, r_u_left);
+		assertGreaterThan(r_u_left, r_u_right);
+	}
+
+	@Test
+	public void testCompareRightDownButLowerRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_d_left = segment(e13, p, DOWN, RIGHT, DOWN, LEFT);
+		ColumnSegment<TestEdge> r_d_right = segment(e14, p, DOWN, RIGHT, DOWN, RIGHT);
+
+		assertLessThan(r_d_left, r_d_right);
+		assertGreaterThan(r_d_right, r_d_left);
+	}
+
+	@Test
+	public void testCompareLeftUpLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_u_left = segment(e13, p, DOWN, LEFT, UP, LEFT, DOWN);
+		ColumnSegment<TestEdge> l_u_left2 = segment(e14, p, DOWN, LEFT, UP, LEFT_2, DOWN);
+
+		assertLessThan(l_u_left2, l_u_left);
+		assertGreaterThan(l_u_left, l_u_left2);
+	}
+
+	@Test
+	public void testCompareLeftUpRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_u_right = segment(e13, p, DOWN, LEFT, UP, RIGHT, DOWN);
+		ColumnSegment<TestEdge> l_u_right2 = segment(e14, p, DOWN, LEFT, UP, RIGHT_2, DOWN);
+
+		assertLessThan(l_u_right, l_u_right2);
+		assertGreaterThan(l_u_right2, l_u_right);
+	}
+
+	@Test
+	public void testCompareLeftDownLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_d_left = segment(e13, p, DOWN, LEFT, DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> l_d_left2 = segment(e14, p, DOWN, LEFT, DOWN, LEFT_2, DOWN);
+
+		assertLessThan(l_d_left2, l_d_left);
+		assertGreaterThan(l_d_left, l_d_left2);
+	}
+
+	@Test
+	public void testCompareLeftDownRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_d_right = segment(e13, p, DOWN, LEFT, DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> l_d_right2 = segment(e14, p, DOWN, LEFT, DOWN, RIGHT_2, DOWN);
+
+		assertLessThan(l_d_right, l_d_right2);
+		assertGreaterThan(l_d_right2, l_d_right);
+	}
+
+	@Test
+	public void testCompareRightUpLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_u_left = segment(e13, p, DOWN, RIGHT, UP, LEFT, DOWN);
+		ColumnSegment<TestEdge> r_u_left2 = segment(e14, p, DOWN, RIGHT, UP, LEFT_2, DOWN);
+
+		assertLessThan(r_u_left2, r_u_left);
+		assertGreaterThan(r_u_left, r_u_left2);
+	}
+
+	@Test
+	public void testCompareRightUpRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_u_right = segment(e13, p, DOWN, RIGHT, UP, RIGHT, DOWN);
+		ColumnSegment<TestEdge> r_u_right2 = segment(e14, p, DOWN, RIGHT, UP, RIGHT_2, DOWN);
+
+		assertLessThan(r_u_right, r_u_right2);
+		assertGreaterThan(r_u_right2, r_u_right);
+	}
+
+	@Test
+	public void testCompareRightDownLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_d_left = segment(e13, p, DOWN, RIGHT, DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> r_d_left2 = segment(e14, p, DOWN, RIGHT, DOWN, LEFT_2, DOWN);
+
+		assertLessThan(r_d_left2, r_d_left);
+		assertGreaterThan(r_d_left, r_d_left2);
+	}
+
+	@Test
+	public void testCompareRightDownRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_d_right = segment(e13, p, DOWN, RIGHT, DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> r_d_right2 = segment(e14, p, DOWN, RIGHT, DOWN, RIGHT_2, DOWN);
+
+		assertLessThan(r_d_right, r_d_right2);
+		assertGreaterThan(r_d_right2, r_d_right);
+	}
+
+//==================================================================================================
+// The following tests compare ending edge segments.
+//=================================================================================================
+
+	@Test
+	public void testCompareEndsInTotallyDifferentColumns() {
+		GridPoint p1 = p(0, 0);
+		GridPoint p2 = p(0, 1);
+
+		ColumnSegment<TestEdge> col0 = endSegment(e12, p1, UP_2);
+		ColumnSegment<TestEdge> col1 = endSegment(e12, p2, UP_2);
+		assertLessThan(col0, col1);
+		assertGreaterThan(col1, col0);
+	}
+
+	@Test
+	public void testCompareEndsFromDifferentDirections() {
+		GridPoint p = p(5, 5);
+
+		ColumnSegment<TestEdge> fromRight = endSegment(e14, p, UP, RIGHT, UP);
+		ColumnSegment<TestEdge> fromAbove = endSegment(e24, p, UP);
+		ColumnSegment<TestEdge> fromLeft = endSegment(e34, p, UP, LEFT, UP);
+
+		assertLessThan(fromLeft, fromAbove);
+		assertLessThan(fromAbove, fromRight);
+		assertLessThan(fromLeft, fromRight);
+
+		assertGreaterThan(fromAbove, fromLeft);
+		assertGreaterThan(fromRight, fromAbove);
+		assertGreaterThan(fromRight, fromAbove);
+
+	}
+
+	@Test
+	public void testCompareEndBothLeftButDifferentRowLevels() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> up1_left = endSegment(e13, p, UP, LEFT, UP);
+		ColumnSegment<TestEdge> up2_left = segment(e23, p, UP_2, LEFT, UP);
+
+		assertLessThan(up1_left, up2_left);
+		assertGreaterThan(up2_left, up1_left);
+
+	}
+
+	@Test
+	public void testCompareEndBothRightButDifferentRowLevels() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> up1_right = endSegment(e13, p, UP, RIGHT, UP);
+		ColumnSegment<TestEdge> up2_right = segment(e23, p, UP_2, RIGHT, UP);
+
+		assertLessThan(up2_right, up1_right);
+		assertGreaterThan(up1_right, up2_right);
+
+	}
+
+	@Test
+	public void testCompareEndBothLeftThenOppositeDirection() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> u_l_up = endSegment(e13, p, UP, LEFT, UP);
+		ColumnSegment<TestEdge> u_l_down = endSegment(e14, p, UP, LEFT, DOWN);
+
+		assertLessThan(u_l_down, u_l_up);
+		assertGreaterThan(u_l_up, u_l_down);
+
+	}
+
+	@Test
+	public void testCompareEndBothRightsThenOppositeDirection() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> u_r_up = endSegment(e13, p, UP, RIGHT, UP);
+		ColumnSegment<TestEdge> u_r_down = endSegment(e14, p, UP, RIGHT, DOWN);
+
+		assertLessThan(u_r_up, u_r_down);
+		assertGreaterThan(u_r_down, u_r_up);
+
+	}
+
+	@Test
+	public void testCompareEndsLeftDownButDifferentLeftColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> left1 = endSegment(e13, p, UP, LEFT, DOWN);
+		ColumnSegment<TestEdge> left2 = endSegment(e14, p, UP, LEFT_2, DOWN);
+
+		assertLessThan(left1, left2);
+		assertGreaterThan(left2, left1);
+	}
+
+	@Test
+	public void testCompareEndsLeftUpButDifferentLeftColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> left1 = endSegment(e13, p, UP, LEFT, UP);
+		ColumnSegment<TestEdge> left2 = endSegment(e14, p, UP, LEFT_2, UP);
+
+		assertLessThan(left2, left1);
+		assertGreaterThan(left1, left2);
+	}
+
+	@Test
+	public void testCompareEndsRightDownButDifferentRightColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> right1 = endSegment(e13, p, UP, RIGHT, DOWN);
+		ColumnSegment<TestEdge> right2 = endSegment(e14, p, UP, RIGHT_2, DOWN);
+
+		assertLessThan(right2, right1);
+		assertGreaterThan(right1, right2);
+	}
+
+	@Test
+	public void testCompareEndsRightUpButDifferentRightColumn() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> right1 = endSegment(e13, p, UP, RIGHT, UP);
+		ColumnSegment<TestEdge> right2 = endSegment(e14, p, UP, RIGHT_2, UP);
+
+		assertLessThan(right1, right2);
+		assertGreaterThan(right2, right1);
+	}
+
+	@Test
+	public void testCompareEndsLeftUpButUpperRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_u_left = endSegment(e13, p, UP, LEFT, UP, LEFT, UP);
+		ColumnSegment<TestEdge> l_u_right = endSegment(e14, p, UP, LEFT, UP, RIGHT, UP);
+
+		assertLessThan(l_u_left, l_u_right);
+		assertGreaterThan(l_u_right, l_u_left);
+	}
+
+	@Test
+	public void testCompareEndsLeftDownButLowerRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_d_left = endSegment(e13, p, UP, LEFT, DOWN, LEFT, UP);
+		ColumnSegment<TestEdge> l_d_right = endSegment(e14, p, UP, LEFT, DOWN, RIGHT, UP);
+
+		assertLessThan(l_d_right, l_d_left);
+		assertGreaterThan(l_d_left, l_d_right);
+	}
+
+	@Test
+	public void testCompareEndsRightUpButUpperRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_u_left = endSegment(e13, p, UP, RIGHT, UP, LEFT, UP);
+		ColumnSegment<TestEdge> r_u_right = endSegment(e14, p, UP, RIGHT, UP, RIGHT, UP);
+
+		assertLessThan(r_u_left, r_u_right);
+		assertGreaterThan(r_u_right, r_u_left);
+	}
+
+	@Test
+	public void testCompareEndsRightDownButLowerRowDifferentDirections() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_d_left = endSegment(e13, p, UP, RIGHT, DOWN, LEFT, UP);
+		ColumnSegment<TestEdge> r_d_right = endSegment(e14, p, UP, RIGHT, DOWN, RIGHT, UP);
+
+		assertLessThan(r_d_right, r_d_left);
+		assertGreaterThan(r_d_left, r_d_right);
+	}
+
+	@Test
+	public void testCompareEndsLeftUpLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_u_left = endSegment(e13, p, UP, LEFT, UP, LEFT, UP);
+		ColumnSegment<TestEdge> l_u_left2 = endSegment(e14, p, UP, LEFT, UP, LEFT_2, UP);
+
+		assertLessThan(l_u_left2, l_u_left);
+		assertGreaterThan(l_u_left, l_u_left2);
+	}
+
+	@Test
+	public void testCompareEndsLeftUpRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_u_right = endSegment(e13, p, UP, LEFT, UP, RIGHT, UP);
+		ColumnSegment<TestEdge> l_u_right2 = endSegment(e14, p, UP, LEFT, UP, RIGHT_2, UP);
+
+		assertLessThan(l_u_right, l_u_right2);
+		assertGreaterThan(l_u_right2, l_u_right);
+	}
+
+	@Test
+	public void testCompareEndsLeftDownLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_d_left = endSegment(e13, p, UP, LEFT, DOWN, LEFT, UP);
+		ColumnSegment<TestEdge> l_d_left2 = endSegment(e14, p, UP, LEFT, DOWN, LEFT_2, UP);
+
+		assertLessThan(l_d_left2, l_d_left);
+		assertGreaterThan(l_d_left, l_d_left2);
+	}
+
+	@Test
+	public void testCompareEndsLeftDownRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> l_d_right = endSegment(e13, p, UP, LEFT, DOWN, RIGHT, UP);
+		ColumnSegment<TestEdge> l_d_right2 = endSegment(e14, p, UP, LEFT, DOWN, RIGHT_2, UP);
+
+		assertLessThan(l_d_right, l_d_right2);
+		assertGreaterThan(l_d_right2, l_d_right);
+	}
+
+	@Test
+	public void testCompareEndsRightUpLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_u_left = endSegment(e13, p, UP, RIGHT, UP, LEFT, UP);
+		ColumnSegment<TestEdge> r_u_left2 = endSegment(e14, p, UP, RIGHT, UP, LEFT_2, UP);
+
+		assertLessThan(r_u_left2, r_u_left);
+		assertGreaterThan(r_u_left, r_u_left2);
+	}
+
+	@Test
+	public void testCompareEndsRightUpRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_u_right = endSegment(e13, p, UP, RIGHT, UP, RIGHT, UP);
+		ColumnSegment<TestEdge> r_u_right2 = endSegment(e14, p, UP, RIGHT, UP, RIGHT_2, UP);
+
+		assertLessThan(r_u_right, r_u_right2);
+		assertGreaterThan(r_u_right2, r_u_right);
+	}
+
+	@Test
+	public void testCompareEndsRightDownLeftButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_d_left = endSegment(e13, p, UP, RIGHT, DOWN, LEFT, UP);
+		ColumnSegment<TestEdge> r_d_left2 = endSegment(e14, p, UP, RIGHT, DOWN, LEFT_2, UP);
+
+		assertLessThan(r_d_left2, r_d_left);
+		assertGreaterThan(r_d_left, r_d_left2);
+	}
+
+	@Test
+	public void testCompareEndsRightDownRightButFinalColDiffers() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> r_d_right = endSegment(e13, p, UP, RIGHT, DOWN, RIGHT, UP);
+		ColumnSegment<TestEdge> r_d_right2 = endSegment(e14, p, UP, RIGHT, DOWN, RIGHT_2, UP);
+
+		assertLessThan(r_d_right, r_d_right2);
+		assertGreaterThan(r_d_right2, r_d_right);
+	}
+
+//==================================================================================================
+// The following tests compare interior edge segments are consistent with each other
+//=================================================================================================
+	@Test
+	public void testInteriorRightDownRight() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, RIGHT, DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, RIGHT, DOWN, RIGHT_2, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+	@Test
+	public void testInteriorRightDownLeft() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, RIGHT, DOWN, LEFT_2, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, RIGHT, DOWN, LEFT, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+	@Test
+	public void testInteriorRightUpRight() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, RIGHT, UP, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, RIGHT, UP, RIGHT_2, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg2, colSeg1);
+		assertGreaterThan(colSeg1, colSeg2);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+	@Test
+	public void testInteriorRightUpLeft() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, RIGHT, UP, LEFT_2, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, RIGHT, UP, LEFT, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg2, colSeg1);
+		assertGreaterThan(colSeg1, colSeg2);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+	@Test
+	public void testInteriorLeftDownRight() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, LEFT, DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, LEFT, DOWN, RIGHT_2, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+	@Test
+	public void testInteriorLeftDownLeft() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, LEFT, DOWN, LEFT_2, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, LEFT, DOWN, LEFT, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+	@Test
+	public void testInteriorLeftUpRight() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, LEFT, UP, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, LEFT, UP, RIGHT_2, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg2, colSeg1);
+		assertGreaterThan(colSeg1, colSeg2);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg2, rowSeg1);
+		assertGreaterThan(rowSeg1, rowSeg2);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+	@Test
+	public void testInteriorLeftUpLeft() {
+		GridPoint p = p(0, 0);
+
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p, DOWN, LEFT, UP, LEFT_2, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p, DOWN, LEFT, UP, LEFT, DOWN);
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+
+		RowSegment<TestEdge> rowSeg1 = colSeg1.nextSegment();
+		RowSegment<TestEdge> rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg2, colSeg1);
+		assertGreaterThan(colSeg1, colSeg2);
+
+		rowSeg1 = colSeg1.nextSegment();
+		rowSeg2 = colSeg2.nextSegment();
+		assertLessThan(rowSeg1, rowSeg2);
+		assertGreaterThan(rowSeg2, rowSeg1);
+
+		colSeg1 = rowSeg1.nextSegment();
+		colSeg2 = rowSeg2.nextSegment();
+		assertLessThan(colSeg1, colSeg2);
+		assertGreaterThan(colSeg2, colSeg1);
+	}
+
+//==================================================================================================
+// The following tests are for miscellaneous methods in ColumnSegment or RowSegment
+//=================================================================================================
+	@Test
+	public void testColumnSegmentOverlapColumn1TotallyAboveColumn2() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(100, 0), DOWN);
+		assertFalse(colSeg1.overlaps(colSeg2));
+		assertFalse(colSeg2.overlaps(colSeg1));
+	}
+
+	@Test
+	public void testColumnSegmentEndDoesNotOverlapColumnSegmentStartToSameVertex() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(2, 0), DOWN);
+		assertFalse(colSeg1.overlaps(colSeg2));
+	}
+
+	@Test
+	public void testColumnStartSegmentToSharedRowFromEndSegmentDependsOnRowOffsets() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 1), DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 0), DOWN, RIGHT, DOWN);
+		assertTrue(colSeg1.overlaps(colSeg2.last()));
+
+		// now fix offset for secondRow to be down a bit
+		colSeg2.nextSegment().setOffset(1);
+		assertFalse(colSeg1.overlaps(colSeg2.last()));
+	}
+
+	@Test
+	public void testRowSegmentOverlapSeg1TotallyBeforeSeg2() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 10), DOWN, RIGHT, DOWN);
+		assertFalse(colSeg1.nextSegment().overlaps(colSeg2.nextSegment()));
+		assertFalse(colSeg2.nextSegment().overlaps(colSeg1.nextSegment()));
+	}
+
+	@Test
+	public void testRowsLeavingSameVertexInOppositeDirectionsDontOverlap() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 0), DOWN, RIGHT, DOWN);
+		assertFalse(colSeg1.nextSegment().overlaps(colSeg2.nextSegment()));
+		assertFalse(colSeg2.nextSegment().overlaps(colSeg1.nextSegment()));
+	}
+
+	@Test
+	public void testRowsLeavingSameVertexInSameDirectionOverlap() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 0), DOWN, LEFT, DOWN);
+		assertTrue(colSeg1.nextSegment().overlaps(colSeg2.nextSegment()));
+		assertTrue(colSeg2.nextSegment().overlaps(colSeg1.nextSegment()));
+	}
+
+	@Test
+	public void testRowsEnteringSameVertexInOppositeDirectionsDontOverlap() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 2), DOWN, LEFT, DOWN);
+		assertFalse(colSeg1.nextSegment().overlaps(colSeg2.nextSegment()));
+		assertFalse(colSeg2.nextSegment().overlaps(colSeg1.nextSegment()));
+	}
+
+	@Test
+	public void testRowsEnteringSameVertexInSameDirectionsOverlap() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN, RIGHT_2, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 1), DOWN, RIGHT, DOWN);
+		assertTrue(colSeg1.nextSegment().overlaps(colSeg2.nextSegment()));
+		assertTrue(colSeg2.nextSegment().overlaps(colSeg1.nextSegment()));
+	}
+
+	@Test
+	public void testRowsThatStartEndOnSameColumnAndOneIsTerminalAndOtherIsnt() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 0), DOWN, RIGHT, DOWN, RIGHT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 1), DOWN, RIGHT, DOWN);
+		assertTrue(colSeg1.nextSegment().overlaps(colSeg2.nextSegment()));
+		assertTrue(colSeg2.nextSegment().overlaps(colSeg1.nextSegment()));
+
+	}
+
+	@Test
+	public void testRowsThatStartEndOnSameColumnAndOneIsTerminalAndOtherIsntLeft() {
+		ColumnSegment<TestEdge> colSeg1 = segment(e13, p(0, 1), DOWN, LEFT, DOWN, LEFT, DOWN);
+		ColumnSegment<TestEdge> colSeg2 = segment(e14, p(0, 0), DOWN, LEFT, DOWN);
+		assertTrue(colSeg1.nextSegment().overlaps(colSeg2.nextSegment()));
+		assertTrue(colSeg2.nextSegment().overlaps(colSeg1.nextSegment()));
+
+	}
+
+	private void assertCompareEquals(ColumnSegment<TestEdge> s1, ColumnSegment<TestEdge> s2) {
+		int result = s1.compareTo(s2);
+		if (result != 0) {
+			fail("Expected comparsion to be equals, but compareTo was " + result);
+		}
+	}
+
+	private void assertLessThan(ColumnSegment<TestEdge> s1, ColumnSegment<TestEdge> s2) {
+		int result = s1.compareTo(s2);
+		if (result >= 0) {
+			fail("Expected comparsion to be less than, but compareTo was " + result);
+		}
+	}
+
+	private void assertGreaterThan(RowSegment<TestEdge> s1, RowSegment<TestEdge> s2) {
+		int result = s1.compareTo(s2);
+		if (result <= 0) {
+			fail("Expected comparsion to be greater than, but compareTo was " + result);
+		}
+	}
+
+	private void assertLessThan(RowSegment<TestEdge> s1, RowSegment<TestEdge> s2) {
+		int result = s1.compareTo(s2);
+		if (result >= 0) {
+			fail("Expected comparsion to be less than, but compareTo was " + result);
+		}
+	}
+
+	private void assertGreaterThan(ColumnSegment<TestEdge> s1, ColumnSegment<TestEdge> s2) {
+		int result = s1.compareTo(s2);
+		if (result <= 0) {
+			fail("Expected comparsion to be greater than, but compareTo was " + result);
+		}
+	}
+
+	private ColumnSegment<TestEdge> segment(TestEdge e, GridPoint p, int... flows) {
+		return new ColumnSegment<>(e, points(p, flows));
+	}
+
+	private ColumnSegment<TestEdge> endSegment(TestEdge e, GridPoint end, int... flows) {
+		return new ColumnSegment<>(e, pointsReverseOrder(end, flows)).last();
+	}
+
+	private GridPoint p(int row, int col) {
+		return new GridPoint(row, col);
+	}
+
+	private List<GridPoint> points(GridPoint start, int... flows) {
+		List<GridPoint> points = new ArrayList<>();
+		points.add(start);
+		GridPoint next = new GridPoint(start.row, start.col);
+		for (int i = 0; i < flows.length; i++) {
+			if (i % 2 == 0) {
+				next.row += flows[i];
+			}
+			else {
+				next.col += flows[i];
+			}
+			points.add(new GridPoint(next.row, next.col));
+		}
+		return points;
+	}
+
+	private List<GridPoint> pointsReverseOrder(GridPoint end, int... flows) {
+		List<GridPoint> points = new ArrayList<>();
+		points.add(end);
+		GridPoint next = new GridPoint(end.row, end.col);
+		for (int i = 0; i < flows.length; i++) {
+			if (i % 2 == 0) {
+				next.row += flows[i];
+			}
+			else {
+				next.col += flows[i];
+			}
+			points.add(new GridPoint(next.row, next.col));
+		}
+		Collections.reverse(points);
+		return points;
+	}
+
+	private TestVertex v(int id) {
+		return new TestVertex(Integer.toString(id));
+	}
+
+	private TestEdge e(TestVertex vertex1, TestVertex vertex2) {
+		return new TestEdge(v1, v2);
+	}
+
+}

Ghidra/Features/FunctionGraphDecompilerExtension/src/main/java/ghidra/app/plugin/core/functiongraph/graph/layout/DecompilerNestedLayout.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -171,9 +171,8 @@ public class DecompilerNestedLayout extends AbstractFGLayout {
 
 		Address entryPoint = function.getEntryPoint();
 		FGVertex vertex = getVertex(jungGraph, entryPoint);
-		Integer row = gridLocations.row(vertex);
-		Integer col = gridLocations.col(vertex);
-		if (row != 0 || col != 0) {
+		GridPoint gridPoint = gridLocations.gridPoint(vertex);
+		if (gridPoint.row != 0 && gridPoint.col != 0) {
 			Msg.debug(this, "Function graph has entry point not at top of layout: " + entryPoint);
 		}
 
@@ -338,7 +337,7 @@ public class DecompilerNestedLayout extends AbstractFGLayout {
 		int startColumn = Math.min(start.columnIndex, end.columnIndex);
 		int endColumn = Math.max(start.columnIndex, end.columnIndex);
 
-		Column rightmostLoopColumn = layoutToGridMap.col(rightmostLoopVertex);
+		Column<FGVertex> rightmostLoopColumn = layoutToGridMap.col(rightmostLoopVertex);
 		endColumn = Math.max(endColumn, rightmostLoopColumn.index);
 
 		// Look for any vertices that are no part of the loop, but are placed inside
@@ -351,8 +350,8 @@ public class DecompilerNestedLayout extends AbstractFGLayout {
 		// place the right x position to the right of the rightmost vertex, not
 		// extending past the next column
 		FGVertex rightmostVertex = getRightmostVertex(interlopers);
-		Column rightmostColumn = layoutToGridMap.col(rightmostVertex);
-		Column nextColumn = layoutToGridMap.nextColumn(rightmostColumn);
+		Column<FGVertex> rightmostColumn = layoutToGridMap.col(rightmostVertex);
+		Column<FGVertex> nextColumn = layoutToGridMap.nextColumn(rightmostColumn);
 		Vertex2d rightmostV2d = vertex2dFactory.get(rightmostVertex);
 
 		// the padding used for these two lines is somewhat arbitrary and may be changed
@@ -646,7 +645,7 @@ public class DecompilerNestedLayout extends AbstractFGLayout {
 		}
 		else {
 			// going up we swing out to the right; grab the column that is out to the right
-			Column rightColumn = vertex2dFactory.getColumn(edgeX);
+			Column<FGVertex> rightColumn = vertex2dFactory.getColumn(edgeX);
 			endColumn = rightColumn.index;
 		}
 
@@ -855,7 +854,7 @@ public class DecompilerNestedLayout extends AbstractFGLayout {
 	}
 
 	@Override
-	protected Point2D getVertexLocation(FGVertex v, Column col, Row<FGVertex> row,
+	protected Point2D getVertexLocation(FGVertex v, Column<FGVertex> col, Row<FGVertex> row,
 			Rectangle bounds) {
 		return getCenteredVertexLocation(v, col, row, bounds);
 	}
@@ -1128,7 +1127,7 @@ public class DecompilerNestedLayout extends AbstractFGLayout {
 			this.edgeOffset = edgeOffset;
 		}
 
-		Column getColumn(double x) {
+		Column<FGVertex> getColumn(double x) {
 			return layoutToGridMap.getColumnContaining((int) x);
 		}
 
@@ -1163,7 +1162,7 @@ public class DecompilerNestedLayout extends AbstractFGLayout {
 
 		private FGVertex v;
 		private Row<FGVertex> row;
-		private Column column;
+		private Column<FGVertex> column;
 		private int rowIndex;
 		private int columnIndex;
 		private Point2D center; // center point of vertex shape

Ghidra/Features/GraphFunctionCalls/src/main/java/functioncalls/graph/layout/BowTieLayout.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -63,7 +63,7 @@ public class BowTieLayout extends AbstractVisualGraphLayout<FcgVertex, FcgEdge>
 	}
 
 	@Override
-	protected Point2D getVertexLocation(FcgVertex v, Column col, Row<FcgVertex> row,
+	protected Point2D getVertexLocation(FcgVertex v, Column<FcgVertex> col, Row<FcgVertex> row,
 			Rectangle bounds) {
 		return getCenteredVertexLocation(v, col, row, bounds);
 	}

Ghidra/Framework/Generic/src/main/java/util/CollectionUtils.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -485,4 +485,21 @@ public class CollectionUtils {
 		}
 		return null;
 	}
+
+	/**
+	 * Returns the only element from the given collection; null if the collection is null or empty
+	 * or size is greater than 1. This is meant to clients to get the one and only element in 
+	 * a collection of size 1.
+	 *
+	 * @param c the collection
+	 * @return the item
+	 * @see #any(Collection)
+	 */
+	public static <T> T get(Collection<T> c) {
+		if (c == null || c.size() > 1) {
+			return null;
+		}
+		return any((Iterable<T>) c);
+	}
+
 }

Ghidra/Framework/Graph/src/main/java/ghidra/graph/GraphAlgorithms.java

@@ -627,4 +627,48 @@ public class GraphAlgorithms {
 			recursivePrint(g, v2, set, depth + 1, ps);
 		}
 	}
+
+	/**
+	 * Returns a list of list of vertices sorted topologically such that for every edge 
+	 * V1 -> V2, the V1 vertex will appear in the resulting list before the V2 vertex. Normally,
+	 * this is only defined for acyclic graphs. For purposes of this implementation, a root vertex 
+	 * is given as a start point and any edge encountered by following edges from the root that
+	 * results in a "back" edge (i.e any edge that points to a previously visited vertex) is 
+	 * ignored, effectively making the graph acyclic (somewhat arbitrarily depending the order in
+	 * which vertexes are visited which is determined by the given edge comparator). Also, note
+	 * that any vertex in the graph that is not reachable from the given root will not appear in
+	 * the resulting list of sorted vertices.
+	 *  
+	 * @param <V> the vertex type
+	 * @param <E> the edge type
+	 * @param g the graph
+	 * @param root the start node for traversing the graph (will always be the first node in the
+	 * resulting list)
+	 * @param edgeComparator provides an ordering for traversing the graph which can impact which
+	 * edges are ignored as "back" edges and ultimately affect the final ordering
+	 * @return a list of vertices reachable from the given root vertex, sorted topologically
+	 */
+	public static <V, E extends GEdge<V>> List<V> topologicalSort(GDirectedGraph<V, E> g, V root,
+			Comparator<E> edgeComparator) {
+		GraphToTreeAlgorithm<V, E> algorithm = new GraphToTreeAlgorithm<V, E>(g, edgeComparator);
+		return algorithm.topolocigalSort(root);
+	}
+
+	/**
+	 * Converts a general directed graph into a tree graph with the given vertex as the root. It
+	 * does this by first doing a topological sort (which ignores back edges) and greedily accepting
+	 * the first incoming edge based on the sorted vertex order. 
+	 * @param <V> the vertex type
+	 * @param <E> the edge type
+	 * @param g the graph to be converted into a tree
+	 * @param root the vertex to be used as the root
+	 * @param edgeComparator provides a priority ordering of edges with higher priority edges 
+	 * getting first shot at claiming children for its sub-tree.
+	 * @return a graph with edges removed such that the graph is a tree.
+	 */
+	public static <V, E extends GEdge<V>> GDirectedGraph<V, E> toTree(GDirectedGraph<V, E> g,
+			V root, Comparator<E> edgeComparator) {
+		GraphToTreeAlgorithm<V, E> algorithm = new GraphToTreeAlgorithm<V, E>(g, edgeComparator);
+		return algorithm.toTree(root);
+	}
 }

Ghidra/Framework/Graph/src/main/java/ghidra/graph/GraphToTreeAlgorithm.java

@@ -0,0 +1,216 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph;
+
+import java.util.*;
+
+import org.apache.commons.collections4.map.LazyMap;
+
+import ghidra.graph.jung.JungDirectedGraph;
+
+/**
+ * This class provides an algorithm for topological graph sorting and an algorithm for using
+ * that topological sort to create a tree structure from the graph using that topological sort.
+ * <P>
+ * In general topological sorting and converting to a tree, require an acyclic graph. However,
+ * by supplying a root vertex, the graph can be made to be acyclic by traversing the graph from 
+ * that root and discarding any edges the return to a "visited" vertex. This has a side effect of
+ * ignoring any nodes that are not reachable from the root node. Also, this algorithm class is 
+ * constructed with an edge comparator which can also determine the order nodes are traversed,
+ * thereby affecting the final ordering or tree structure. Higher priority edges will be processed
+ * first, making those edges least likely to be removed as "back" edges.
+ * <P>
+ * To convert a general graph to a tree, some subset of the the graphs original edges are used to
+ * form the tree. There are many possible different trees that can be created in this way. This
+ * algorimth's goal is to create a tree such that if all the original "forward" edges are added 
+ * back to the tree, they only flow down the tree. This is useful for creating a nicely organized
+ * layout of vertices and edges when drawn.
+ * 
+ * @param <V> The vertex type
+ * @param <E> The edge type
+ */
+public class GraphToTreeAlgorithm<V, E extends GEdge<V>> {
+	private GDirectedGraph<V, E> graph;
+	private Comparator<E> edgeComparator;
+
+	/**
+	 * Constructor.
+	 * 
+	 * @param graph the graph from with to create a tree
+	 * @param edgeComparator provides a priority ordering of edges with higher priority edges 
+	 * getting first shot at claiming children for its sub-tree.
+	 */
+	public GraphToTreeAlgorithm(GDirectedGraph<V, E> graph, Comparator<E> edgeComparator) {
+		this.graph = graph;
+		this.edgeComparator = edgeComparator;
+	}
+
+	/**
+	 * Creates a tree graph with the given vertex as the root from this object's graph.
+	 * 
+	 * @param root the vertex to be used as the root
+	 * getting first shot at claiming children for its sub-tree.
+	 * @return a graph with edges removed such that the graph is a tree.
+	 */
+	public GDirectedGraph<V, E> toTree(V root) {
+
+		// first sort the vertices topologically
+		List<V> sorted = topolocigalSort(root);
+
+		// Visit nodes in the sorted order and track the longest path to each node from the root.
+		Map<V, Depth> depthMap = assignDepths(root, sorted);
+
+		// Assign vertices to the tree in the sorted order and only using edges where the "from"
+		// vertex (parent) is at a depth 1 less then the depth of "to" vertex. This will ensure
+		// that the tree is ordered such that if all the original forward edges are added back in,
+		// they would always flow down the tree.
+		return createTree(root, sorted, depthMap);
+
+	}
+
+	/**
+	 * Sorts the vertices in this graph topologically.
+	 * 
+	 * @param root the start node for traversing the graph (will always be the first node in the
+	 * resulting list)
+	 * @return a list of vertices reachable from the given root vertex, sorted topologically
+	 */
+	public List<V> topolocigalSort(V root) {
+
+		Set<V> visited = new HashSet<>();
+		List<V> ordered = new ArrayList<>();
+
+		Deque<VertexChildIterator> stack = new ArrayDeque<>();
+
+		stack.push(new VertexChildIterator(root));
+		visited.add(root);
+
+		while (!stack.isEmpty()) {
+			VertexChildIterator childIterator = stack.getFirst();
+			if (childIterator.hasNext()) {
+				V child = childIterator.next();
+
+				// only process the child if never seen before, otherwise it is a loop back
+				if (!visited.contains(child)) {
+					stack.push(new VertexChildIterator(child));
+					visited.add(child);
+				}
+			}
+			else {
+				ordered.add(childIterator.getParent());
+				stack.pop();
+			}
+		}
+		Collections.reverse(ordered);
+		return ordered;
+	}
+
+	private JungDirectedGraph<V, E> createTree(V root, List<V> sorted, Map<V, Depth> depthMap) {
+		Set<V> visited = new HashSet<>();
+		visited.add(root);
+
+		JungDirectedGraph<V, E> tree = new JungDirectedGraph<V, E>();
+		for (V v : sorted) {
+			tree.addVertex(v);
+		}
+
+		for (V parent : sorted) {
+			Depth parentDepth = depthMap.get(parent);
+			Collection<E> outEdges = graph.getOutEdges(parent);
+			for (E e : outEdges) {
+				V child = e.getEnd();
+				if (visited.contains(child)) {
+					continue;  // already assigned
+				}
+				Depth childDepth = depthMap.get(child);
+				if (childDepth.isDirectChildOf(parentDepth)) {
+					tree.addEdge(e);
+					visited.add(child);
+				}
+			}
+		}
+		return tree;
+	}
+
+	private Map<V, Depth> assignDepths(V root, List<V> sorted) {
+
+		Set<V> visited = new HashSet<>();
+		Map<V, Depth> depthMap = LazyMap.lazyMap(new HashMap<>(), k -> new Depth());
+
+		depthMap.put(root, new Depth());
+		for (V parent : sorted) {
+			visited.add(parent);
+			Depth parentDepth = depthMap.get(parent);
+			List<E> edges = new ArrayList<>();
+			Collection<E> out = graph.getOutEdges(parent);
+			if (out != null) {
+				edges.addAll(out);
+			}
+			edges.sort(edgeComparator);
+			for (E e : edges) {
+				V child = e.getEnd();
+				if (visited.contains(child)) {
+					continue;		// loop backs are ignored
+				}
+				Depth childDepth = depthMap.get(child);
+				childDepth.adjustDepth(parentDepth);
+			}
+		}
+		return depthMap;
+	}
+
+	// traces the distance from the root of the tree
+	private static class Depth {
+		private int depth = 0;
+
+		private void adjustDepth(Depth parentDepth) {
+			depth = Math.max(depth, parentDepth.depth + 1);
+		}
+
+		private boolean isDirectChildOf(Depth parentDepth) {
+			return depth == parentDepth.depth + 1;
+		}
+	}
+
+	private class VertexChildIterator {
+		private V parent;
+		private Iterator<E> it;
+
+		VertexChildIterator(V parent) {
+			this.parent = parent;
+			Collection<E> out = graph.getOutEdges(parent);
+			List<E> outEdges = new ArrayList<>();
+			if (out != null) {
+				outEdges.addAll(out);
+			}
+			outEdges.sort(edgeComparator);
+			it = outEdges.reversed().iterator();
+		}
+
+		V getParent() {
+			return parent;
+		}
+
+		public boolean hasNext() {
+			return it.hasNext();
+		}
+
+		public V next() {
+			return it.next().getEnd();
+		}
+	}
+
+}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/GraphComponent.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -627,7 +627,7 @@ public class GraphComponent<V extends VisualVertex, E extends VisualEdge<V>, G e
 		return satelliteViewer;
 	}
 
-	protected VisualGraphViewUpdater<V, E> getViewUpdater() {
+	public VisualGraphViewUpdater<V, E> getViewUpdater() {
 		return primaryViewer.getViewUpdater();
 	}
 

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/VisualGraphViewUpdater.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -335,8 +335,9 @@ public class VisualGraphViewUpdater<V extends VisualVertex, E extends VisualEdge
 		setGraphScale(graphInfo.getZoom());
 
 		Point layoutPoint = graphInfo.getLayoutTranslateCoordinates();
-		multiLayerTransformer.getTransformer(Layer.LAYOUT).setTranslate(layoutPoint.x,
-			layoutPoint.y);
+		multiLayerTransformer.getTransformer(Layer.LAYOUT)
+				.setTranslate(layoutPoint.x,
+					layoutPoint.y);
 
 		Point viewPoint = graphInfo.getViewTranslateCoordinates();
 		multiLayerTransformer.getTransformer(Layer.VIEW).setTranslate(viewPoint.x, viewPoint.y);
@@ -443,4 +444,8 @@ public class VisualGraphViewUpdater<V extends VisualVertex, E extends VisualEdge
 		stopVertexTwinkleAnimation();
 	}
 
+	public void relayoutGraph() {
+		scheduleViewChangeJob(new RelayoutFunctionGraphJob<>(primaryViewer, isAnimationEnabled()));
+	}
+
 }

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/AbstractVisualGraphLayout.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -337,7 +337,7 @@ public abstract class AbstractVisualGraphLayout<V extends VisualVertex,
 		}
 
 		// DEGUG triggers grid lines to be printed; useful for debugging
-		// VisualGraphRenderer.DEBUG_ROW_COL_MAP.put(this, layoutLocations.copy());
+		// VisualGraphRenderer.setGridPainter(new GridPainter(layoutLocations.getGridCoordinates()));
 
 		layoutLocations.dispose();
 		gridLocations.dispose();
@@ -356,7 +356,7 @@ public abstract class AbstractVisualGraphLayout<V extends VisualVertex,
 			monitor.checkCancelled();
 
 			Row<V> row = layoutLocations.row(vertex);
-			Column column = layoutLocations.col(vertex);
+			Column<V> column = layoutLocations.col(vertex);
 
 			Shape shape = transformer.apply(vertex);
 			Rectangle bounds = shape.getBounds();
@@ -366,7 +366,7 @@ public abstract class AbstractVisualGraphLayout<V extends VisualVertex,
 		return newLocations;
 	}
 
-	protected Point2D getVertexLocation(V v, Column col, Row<V> row, Rectangle bounds) {
+	protected Point2D getVertexLocation(V v, Column<V> col, Row<V> row, Rectangle bounds) {
 		int x = col.x - bounds.x;
 		int y = row.y - bounds.y;
 		return new Point2D.Double(x, y);
@@ -381,7 +381,7 @@ public abstract class AbstractVisualGraphLayout<V extends VisualVertex,
 	 * @param bounds the bounds of the vertex in the layout space
 	 * @return the centered location
 	 */
-	protected Point2D getCenteredVertexLocation(V v, Column col, Row<V> row, Rectangle bounds) {
+	protected Point2D getCenteredVertexLocation(V v, Column<V> col, Row<V> row, Rectangle bounds) {
 		//
 		// Move x over to compensate for vertex painting.   Edges are drawn from the center of the
 		// vertex.  Thus, if you have vertices with two different widths, then the edge between
@@ -409,9 +409,9 @@ public abstract class AbstractVisualGraphLayout<V extends VisualVertex,
 			monitor.checkCancelled();
 
 			List<Point2D> newArticulations = new ArrayList<>();
-			for (Point gridPoint : layoutLocations.articulations(edge)) {
-				Row<V> row = layoutLocations.row(gridPoint.y);
-				Column column = layoutLocations.col(gridPoint.x);
+			for (GridPoint gridPoint : layoutLocations.articulations(edge)) {
+				Row<V> row = layoutLocations.row(gridPoint.row);
+				Column<V> column = layoutLocations.col(gridPoint.col);
 
 				Point2D location = getEdgeLocation(column, row);
 				newArticulations.add(location);
@@ -421,11 +421,11 @@ public abstract class AbstractVisualGraphLayout<V extends VisualVertex,
 		return newEdgeArticulations;
 	}
 
-	protected Point2D getEdgeLocation(Column col, Row<V> row) {
+	protected Point2D getEdgeLocation(Column<V> col, Row<V> row) {
 		return new Point2D.Double(col.x, row.y);
 	}
 
-	protected Point2D getCenteredEdgeLocation(Column col, Row<V> row) {
+	protected Point2D getCenteredEdgeLocation(Column<V> col, Row<V> row) {
 		//
 		// half-height offsets the articulation points, which keeps long edge lines from
 		// overlapping as much

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/Column.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -16,16 +16,22 @@
 package ghidra.graph.viewer.layout;
 
 import java.awt.geom.Point2D;
+import java.util.*;
+import java.util.Map.Entry;
 
 import ghidra.graph.viewer.GraphViewerUtils;
 
 /**
- * A row in a grid.   This class stores it's row index, its x offset and its width.  The
+ * A column in a grid.   This class stores its column index, its x offset and its width.  The
  * x value is the layout space x value of a {@link Point2D} object.   That is, unlike the
  * {@link GridLocationMap}, the x value of this object is in layout space and not indexes 
  * of a grid.
+ * 
+ * <p>This class maintains a collection of vertices on this column, organized by column index.  You
+ * can get the column of a vertex from {@link #getRow(Object)}.
+ * @param <V> The vertex type
  */
-public class Column {
+public class Column<V> {
 
 	/** The <b>layout</b> x coordinate of the column */
 	public int x = -1;
@@ -33,11 +39,26 @@ public class Column {
 
 	/** The grid index of this column (0, 1...n) for the number of columns */
 	public int index = Integer.MAX_VALUE;
+	// Note: these must change together (they are effectively a BiDi map)
+	private TreeMap<Integer, V> verticesByRow = new TreeMap<>();
+	private Map<V, Integer> rowsByVertex = new HashMap<>();
 
 	public Column(int index) {
 		this.index = index;
 	}
 
+	public void setRow(V v, int row) {
+		rowsByVertex.put(v, row);
+		verticesByRow.put(row, v);
+	}
+
+	public int getRow(V v) {
+		if (!rowsByVertex.containsKey(v)) {
+			throw new IllegalArgumentException("Vertex is not in row: " + v);
+		}
+		return rowsByVertex.get(v);
+	}
+
 	public int getPaddedWidth(boolean isCondensed) {
 		if (isCondensed) {
 			return width + GraphViewerUtils.EXTRA_LAYOUT_COLUMN_SPACING_CONDENSED;
@@ -61,4 +82,13 @@ public class Column {
 		"}";
 		//@formatter:on
 	}
+
+	public boolean isOpenBetween(int startRow, int endRow) {
+		Entry<Integer, V> ceilingEntry = verticesByRow.ceilingEntry(startRow);
+		if (ceilingEntry == null) {
+			return true;
+		}
+		int nextRow = ceilingEntry.getKey();
+		return nextRow > endRow;
+	}
 }

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/GridBounds.java

@@ -0,0 +1,100 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph.viewer.layout;
+
+/**
+ * Tracks the minimum and maximum indexes for both rows and columns.
+ */
+
+public class GridBounds {
+	private int minRow = 0;
+	private int maxRow = 0;
+	private int minCol = 0;
+	private int maxCol = 0;
+
+	/**
+	 * Updates the bounds for the given GridPoint.
+	 * @param p the gridPoint used to update the minimums and maximums
+	 */
+	public void update(GridPoint p) {
+		minRow = Math.min(minRow, p.row);
+		maxRow = Math.max(maxRow, p.row);
+		minCol = Math.min(minCol, p.col);
+		maxCol = Math.max(maxCol, p.col);
+	}
+
+	/**
+	 * Shifts the columns bounds by the given amount
+	 * @param rowShift the amount to shift the row bounds.
+	 * @param colShift the amount to shift the column bounds.
+	 * @throws IllegalArgumentException if the shift would make the minimum column negative
+	 */
+	public void shift(int rowShift, int colShift) {
+		minCol += colShift;
+		maxCol += colShift;
+		minRow += rowShift;
+		maxRow += rowShift;
+	}
+
+	@Override
+	public String toString() {
+		StringBuilder buffy = new StringBuilder();
+		buffy.append("Grid Bounds: ");
+		if (minRow == Integer.MAX_VALUE) {
+			return "Empty";
+		}
+
+		buffy.append("rows: ").append(minRow).append(" -> ").append(maxRow);
+		buffy.append(",  ");
+		buffy.append("cols: ").append(minCol).append(" -> ").append(maxCol);
+		return buffy.toString();
+	}
+
+	public int maxCol() {
+		return maxCol;
+	}
+
+	public int minCol() {
+		// handle case when grid is empty
+		if (minCol > maxCol) {
+			return 0;
+		}
+		return minCol;
+	}
+
+	public int maxRow() {
+		return maxRow;
+	}
+
+	public int minRow() {
+		// handle case when grid is empty
+		if (minRow > maxRow) {
+			return 0;
+		}
+		return minRow;
+	}
+
+	public boolean contains(GridPoint p) {
+		if (p.row < minRow || p.row > maxRow) {
+			return false;
+		}
+		if (p.col < minCol || p.col > maxCol) {
+			return false;
+		}
+		return true;
+	}
+
+}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/GridCoordinates.java

@@ -0,0 +1,79 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph.viewer.layout;
+
+import java.awt.Rectangle;
+
+/**
+ * Tracks the mapping of grid coordinates (rows, columns) to space coordinates (x, y)
+ */
+public class GridCoordinates {
+	private int[] rowStarts;
+	private int[] colStarts;
+
+	/**
+	 * Constructor
+	 * @param rowCoordinates an array containing the y locations for all rows in a grid
+	 * @param columnCoordinates an array containing the x locations for all columns in a grid
+	 */
+	public GridCoordinates(int[] rowCoordinates, int[] columnCoordinates) {
+		rowStarts = rowCoordinates;
+		colStarts = columnCoordinates;
+	}
+
+	/**
+	 * Returns the x value for a given column.
+	 * @param col the column index in the grid
+	 * @return the x coordinate assigned to the given column index
+	 */
+	public int x(int col) {
+		return colStarts[col];
+	}
+
+	/**
+	 * Returns the y value for a given row.
+	 * @param row the row index in the grid
+	 * @return the y coordinate assigned to the given row index
+	 */
+	public int y(int row) {
+		return rowStarts[row];
+	}
+
+	/**
+	 * Returns the total bounds for the grid
+	 * @return the total bounds for the grid
+	 */
+	public Rectangle getBounds() {
+		return new Rectangle(0, 0, colStarts[colStarts.length - 1],
+			rowStarts[rowStarts.length - 1]);
+	}
+
+	/**
+	 * returns the number of rows in the grid.
+	 * @return the number of rows in the grid
+	 */
+	public int rowCount() {
+		return rowStarts.length;
+	}
+
+	/**
+	 * returns the number of columns in the grid.
+	 * @return the number of columns in the grid
+	 */
+	public int columnCount() {
+		return colStarts.length;
+	}
+}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/GridLocationMap.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -15,49 +15,86 @@
  */
 package ghidra.graph.viewer.layout;
 
-import java.awt.Point;
 import java.util.*;
 import java.util.Map.Entry;
+import java.util.stream.Stream;
 
-import org.apache.commons.collections4.Factory;
 import org.apache.commons.collections4.map.LazyMap;
 
 /**
- * An object that maps vertices to rows and columns and edges to their articulation points.  
- * This class is essentially a container that allows layout algorithms to store results, which
- * can later be turned into layout positioning points.   The integer point values in this 
- * class are row, column grid values, starting at 0,0.
- * 
- * <P>Note: the Point2D values for the edge articulations use x,y values that are row and 
- * column index values, the same values as calling {@link #row(Object) row(V)} and {@link #col(Object) col(V)}.
- *
- * <P>After building the grid using this class, clients can call {@link #rows()} to get 
- * high-order object that represent rows.
+ * An object that maps vertices and edge articulation points to rows and columns in a grid. This
+ * class is essentially a container that allows layout algorithms to store results as it lays
+ * out vertices and edges in a virtual grid. Later, this information can be used in conjunction 
+ * with vertex size information and padding information to transform these grid coordinates to
+ * layout space coordinates.
+ * <P>
+ * This object also has methods for manipulating the grid such as shifting it up, down, left, right,
+ * and merging in other GridLocationMaps
+ * <P>
+ * After building the grid using this class, clients can call {@link #rows()}, {@link #rowsMap()},
+ * or {@link #columnsMap()} to get high-order objects that represent rows or columns.
  *
  * @param <V> the vertex type
  * @param <E> the edge type
  */
 public class GridLocationMap<V, E> {
 
-	private Factory<Point> rowColFactory = () -> new Point();
+	protected Map<V, GridPoint> vertexPoints =
+		LazyMap.lazyMap(new HashMap<V, GridPoint>(), v -> new GridPoint(0, 0));
 
-	private Map<V, Point> vertexPoints = LazyMap.lazyMap(new HashMap<V, Point>(), rowColFactory);
-	private Map<E, List<Point>> edgePoints = new HashMap<>();
+	protected Map<E, List<GridPoint>> edgePoints = new HashMap<>();
+	private GridBounds gridBounds = new GridBounds();
+	// Tree based algorithms might want to track the column of the root node as it changes when
+	// the grid is shifted or merged.Useful for determining the position of a parent node when
+	// building bottom up.
+	private int rootColumn = 0;
 
-	Set<V> vertices() {
+	public GridLocationMap() {
+		rootColumn = 0;
+	}
+
+	/**
+	 * Constructor that includes an initial "root" vertex.
+	 * @param root the initial vertex
+	 * @param row the row for the initial vertex
+	 * @param col the column for the initial vertex. 
+	 */
+	public GridLocationMap(V root, int row, int col) {
+		this.rootColumn = col;
+		set(root, new GridPoint(row, col));
+	}
+
+	/**
+	 * Returns the column of the initial vertex in this grid.
+	 * @return the column of the initial vertex in this grid
+	 */
+	public int getRootColumn() {
+		return rootColumn;
+	}
+
+	public Set<V> vertices() {
 		return vertexPoints.keySet();
 	}
 
-	Set<E> edges() {
+	public Set<E> edges() {
 		return edgePoints.keySet();
 	}
 
-	public void setArticulations(E edge, List<Point> articulations) {
-		edgePoints.put(edge, articulations);
+	public Map<V, GridPoint> getVertexPoints() {
+		return vertexPoints;
 	}
 
-	public List<Point> getArticulations(E edge) {
-		List<Point> list = edgePoints.get(edge);
+	public void setArticulations(E edge, List<GridPoint> articulations) {
+		edgePoints.put(edge, articulations);
+		if (articulations != null) {
+			for (GridPoint gridPoint : articulations) {
+				gridBounds.update(gridPoint);
+			}
+		}
+	}
+
+	public List<GridPoint> getArticulations(E edge) {
+		List<GridPoint> list = edgePoints.get(edge);
 		if (list == null) {
 			return Collections.emptyList();
 		}
@@ -65,25 +102,44 @@ public class GridLocationMap<V, E> {
 	}
 
 	public void row(V vertex, int row) {
-		vertexPoints.get(vertex).y = row;
+		GridPoint gridPoint = vertexPoints.get(vertex);
+		gridPoint.row = row;
+		gridBounds.update(gridPoint);
 	}
 
 	public void col(V vertex, int col) {
-		vertexPoints.get(vertex).x = col;
+		GridPoint gridPoint = vertexPoints.get(vertex);
+		gridPoint.col = col;
+		gridBounds.update(gridPoint);
 	}
 
 	public void set(V v, int row, int col) {
-		Point p = vertexPoints.get(v);
-		p.x = col;
-		p.y = row;
+		set(v, new GridPoint(row, col));
+	}
+
+	public void set(V v, GridPoint gridPoint) {
+		vertexPoints.put(v, gridPoint);
+		gridBounds.update(gridPoint);
 	}
 
 	public int row(V vertex) {
-		return vertexPoints.get(vertex).y;
+		GridPoint gridPoint = vertexPoints.get(vertex);
+		if (gridPoint != null) {
+			return gridPoint.row;
+		}
+		return 0;
 	}
 
 	public int col(V vertex) {
-		return vertexPoints.get(vertex).x;
+		GridPoint gridPoint = vertexPoints.get(vertex);
+		if (gridPoint != null) {
+			return gridPoint.col;
+		}
+		return 0;
+	}
+
+	public GridPoint gridPoint(V vertex) {
+		return vertexPoints.get(vertex);
 	}
 
 	/**
@@ -92,143 +148,82 @@ public class GridLocationMap<V, E> {
 	 * @return the rows in this grid
 	 */
 	public List<Row<V>> rows() {
-
-		Map<Integer, Row<V>> rowsByIndex = new HashMap<>();
-
-		Set<Entry<V, Point>> entrySet = vertexPoints.entrySet();
-		for (Entry<V, Point> entry : entrySet) {
-			V v = entry.getKey();
-			Point gridPoint = entry.getValue();
-			int rowIndex = gridPoint.y;
-			Row<V> row = getRow(rowsByIndex, rowIndex);
-			row.index = rowIndex;
-			row.setColumn(v, gridPoint.x);
-		}
-
+		Map<Integer, Row<V>> rowsByIndex = rowsMap();
 		List<Row<V>> rows = new ArrayList<>(rowsByIndex.values());
 		rows.sort((r1, r2) -> r1.index - r2.index);
 		return rows;
 	}
 
-	private Row<V> getRow(Map<Integer, Row<V>> rows, int rowIndex) {
-		Row<V> row = rows.get(rowIndex);
-		if (row == null) {
-			row = new Row<>(rowIndex);
-			rows.put(rowIndex, row);
+	/**
+	 * Returns a mapping or row indexes to Row objects in this grid
+	 * 
+	 * @return the rows in this grid
+	 */
+	public Map<Integer, Row<V>> rowsMap() {
+		Map<Integer, Row<V>> rowsByIndex = LazyMap.lazyMap(new HashMap<>(), r -> new Row<V>(r));
+
+		Set<Entry<V, GridPoint>> entrySet = vertexPoints.entrySet();
+		for (Entry<V, GridPoint> entry : entrySet) {
+			V v = entry.getKey();
+			GridPoint gridPoint = entry.getValue();
+			int rowIndex = gridPoint.row;
+			Row<V> row = rowsByIndex.get(rowIndex);
+			row.setColumn(v, gridPoint.col);
 		}
-		return row;
+		return rowsByIndex;
 	}
 
 	/**
-	 * Updates each row within the grid such that it's x values are set to center the row in
+	 * Returns a mapping or column indexes to Column objects in this grid
+	 * 
+	 * @return the columns in this grid
+	 */
+	public Map<Integer, Column<V>> columnsMap() {
+		Map<Integer, Column<V>> columnsMap =
+			LazyMap.lazyMap(new HashMap<>(), c -> new Column<V>(c));
+
+		Set<Entry<V, GridPoint>> entrySet = vertexPoints.entrySet();
+		for (Entry<V, GridPoint> entry : entrySet) {
+			V v = entry.getKey();
+			GridPoint gridPoint = entry.getValue();
+			int colIndex = gridPoint.col;
+			Column<V> col = columnsMap.get(colIndex);
+			col.setRow(v, gridPoint.row);
+		}
+		return columnsMap;
+	}
+
+	/**
+	 * Updates each row within the grid such that it's column values are set to center the row in
 	 * the grid.  Each row will be updated so that all its columns start at zero.  After that, 
 	 * each column will be centered in the grid.
 	 */
 	public void centerRows() {
+		zeroAlignGrid();
+		GridRange[] vertexColumnRanges = getVertexColumnRanges();
+		int maxRowWidth = getMaxRowWidth(vertexColumnRanges);
 
-		List<Row<V>> rows = rows();
-		int maxCol = columnCount(rows);
-		for (Row<V> row : rows) {
-
-			row = zeroRowColumns(row);
-
-			int rowColumnCount = row.getColumnCount();
-			if (rowColumnCount == maxCol) {
-				continue; // already the full size; no need to center
-			}
-
-			int delta = maxCol - rowColumnCount;
-			int offset = delta / 2;
-			List<V> vertices = row.getVertices();
-			for (V v : vertices) {
-				if (v == null) {
-					continue;
-				}
-
-				int oldCol = col(v);
-				set(v, row.index, oldCol + offset);
-			}
-
-			row.dispose();
+		for (GridPoint p : allPoints()) {
+			GridRange range = vertexColumnRanges[p.row];
+			int extraSpace = maxRowWidth - range.width();
+			int shift = extraSpace / 2 - range.min;
+			p.col += shift;
 		}
 	}
 
-	private int maxColumnIndex(List<Row<V>> rows) {
-		int maxCol = 0;
-		for (Row<V> row : rows) {
-			maxCol = Math.max(maxCol, row.getEndColumn());
+	private int getMaxRowWidth(GridRange[] vertexColumnRanges) {
+		int maxWidth = 0;
+		for (GridRange gridRange : vertexColumnRanges) {
+			maxWidth = Math.max(maxWidth, gridRange.width());
 		}
-		return maxCol;
+		return maxWidth;
 	}
 
-	private int maxRowIndex(List<Row<V>> rows) {
-		int maxRow = 0;
-		for (Row<V> row : rows) {
-			maxRow = Math.max(maxRow, row.index);
-		}
-		return maxRow;
-	}
-
-	private int columnCount(List<Row<V>> rows) {
-
-		int maxCount = 0;
-		for (Row<V> row : rows) {
-			maxCount = Math.max(maxCount, row.getColumnCount());
-		}
-		return maxCount;
-	}
-
-//	private int rowCount(List<Row<V>> rows) {
-//		int minRow = 0;
-//		int maxRow = 0;
-//		for (Row<V> row : rows) {
-//			minRow = Math.min(minRow, row.index);
-//			maxRow = Math.max(maxRow, row.index);
-//		}
-//		return (maxRow - minRow) + 1; // +1 for zero-based
-//	}
-
-	private Row<V> zeroRowColumns(Row<V> row) {
-
-		int start = row.getStartColumn();
-		int offset = -start;
-
-		Row<V> updatedRow = new Row<>();
-		updatedRow.index = row.index;
-		for (V v : row.getVertices()) {
-			int oldCol = col(v);
-			int newCol = oldCol + offset;
-			set(v, row.index, newCol);
-			updatedRow.setColumn(v, newCol);
-		}
-
-		row.dispose();
-		return updatedRow;
-	}
-
-	GridLocationMap<V, E> copy() {
-		GridLocationMap<V, E> map = new GridLocationMap<>();
-
-		map.vertexPoints = new HashMap<>();
-		Set<Entry<V, Point>> entries = vertexPoints.entrySet();
-		for (Entry<V, Point> entry : entries) {
-			map.vertexPoints.put(entry.getKey(), (Point) entry.getValue().clone());
-		}
-
-		map.edgePoints = new HashMap<>();
-		Set<Entry<E, List<Point>>> edgeEntries = edgePoints.entrySet();
-		for (Entry<E, List<Point>> entry : edgeEntries) {
-
-			List<Point> points = entry.getValue();
-			List<Point> clonedPoints = new ArrayList<>(points.size());
-			for (Point p : points) {
-				clonedPoints.add((Point) p.clone());
-			}
-
-			map.edgePoints.put(entry.getKey(), clonedPoints);
-		}
-
-		return map;
+	/**
+	 * Shifts the grid so that its first row and column are at 0.
+	 */
+	public void zeroAlignGrid() {
+		shift(-gridBounds.minRow(), -gridBounds.minCol());
 	}
 
 	public void dispose() {
@@ -236,6 +231,103 @@ public class GridLocationMap<V, E> {
 		edgePoints.clear();
 	}
 
+	/**
+	 * Shifts the rows and columns for all points in this map by the given amount.
+	 * @param rowShift the amount to shift the rows of each point
+	 * @param colShift the amount to shift the columns of each point
+	 */
+	public void shift(int rowShift, int colShift) {
+		if (rowShift == 0 && colShift == 0) {
+			return;
+		}
+
+		for (GridPoint p : allPoints()) {
+			p.row += rowShift;
+			p.col += colShift;
+		}
+		rootColumn += colShift;
+		gridBounds.shift(rowShift, colShift);
+
+	}
+
+	/**
+	 * Returns the number of rows in this grid map. Note that this includes empty rows
+	 * starting at the 0 row. 
+	 * @return the number of rows in this grid map
+	 */
+	public int height() {
+		return gridBounds.maxRow() + 1;
+	}
+
+	/**
+	 * Returns the number of columns in this grid map. Note that this includes empty columns 
+	 * starting at the 0 column. 
+	 * @return the number of columns in this grid map
+	 */
+	public int width() {
+		return gridBounds.maxCol() + 1;
+	}
+
+	/**
+	 * Returns the minimum/max column for all rows in the grid. This method is only defined for
+	 * grids that have no negative rows. This is because the array returned will be 0 based, with
+	 * the entry at index 0 containing the column bounds for row 0 and so on.
+	 * @return the minimum/max column for all rows in the grid
+	 * @throws IllegalStateException if this method is called on a grid with negative rows.
+	 */
+	public GridRange[] getVertexColumnRanges() {
+		if (gridBounds.minRow() < 0) {
+			throw new IllegalStateException(
+				"getVertexColumnRanges not defined for grids with negative rows!");
+		}
+		GridRange[] rowRanges = new GridRange[height()];
+
+		for (int i = 0; i < rowRanges.length; i++) {
+			rowRanges[i] = new GridRange();
+		}
+
+		for (GridPoint p : vertexPoints.values()) {
+			rowRanges[p.row].add(p.col);
+		}
+		return rowRanges;
+	}
+
+	public boolean containsVertex(V v) {
+		return vertexPoints.containsKey(v);
+	}
+
+	public boolean containsEdge(E e) {
+		return edgePoints.containsKey(e);
+	}
+
+	/**
+	 * Adds in the vertices and edges from another GridLocationMap with each point in the other
+	 * grid map shifted by the given row and column amounts.
+	 * @param other the other GridLocationMap to add to this one.
+	 * @param rowShift the amount to shift the rows in the grid points from the other grid before
+	 * adding them to this grid
+	 * @param colShift the amount to shift the columns in the grid points from the other grid before
+	 * adding them to this grid
+	 */
+	public void add(GridLocationMap<V, E> other, int rowShift, int colShift) {
+
+		for (Entry<V, GridPoint> entry : other.vertexPoints.entrySet()) {
+			V v = entry.getKey();
+			GridPoint point = entry.getValue();
+			set(v, new GridPoint(point.row + rowShift, point.col + colShift));
+		}
+
+		for (Entry<E, List<GridPoint>> entry : other.edgePoints.entrySet()) {
+			E e = entry.getKey();
+			List<GridPoint> points = entry.getValue();
+			List<GridPoint> shiftedPoints = new ArrayList<>(points.size());
+			for (GridPoint point : points) {
+				shiftedPoints.add(new GridPoint(point.row + rowShift, point.col + colShift));
+			}
+			setArticulations(e, shiftedPoints);
+		}
+	}
+
 	@Override
 	public String toString() {
 		return getClass().getSimpleName() + "[\n\tvertex points=" + vertexPoints +
@@ -247,66 +339,71 @@ public class GridLocationMap<V, E> {
 	 * @return a string representation of this grid
 	 */
 	public String toStringGrid() {
-
-		GridLocationMap<V, E> copy = copy();
-		zeroAlignGrid(copy);
-
-		List<Row<V>> rows = copy.rows();
-		int columnCount = copy.maxColumnIndex(rows) + 1;
-		int rowCount = copy.maxRowIndex(rows) + 1;
-
-		Object[][] vGrid = new Object[rowCount][columnCount];
-		for (Row<V> row : rows) {
-			List<V> vertices = row.getVertices();
-			for (V v : vertices) {
-				vGrid[row.index][row.getColumn(v)] = v;
-			}
+		int minRow = gridBounds.minRow();
+		int minCol = gridBounds.minCol();
+		if (minRow > 10 || minCol > 10) {
+			GridLocationMap<V, E> copy = copy();
+			copy.zeroAlignGrid();
+			return "grid upper left (row,col) = (" + minRow + ", " + minCol + ")\n" +
+				copy.toStringGrid();
 		}
 
-		StringBuilder buffy = new StringBuilder("\n");
-		for (int row = 0; row < rowCount; row++) {
-			for (int col = 0; col < columnCount; col++) {
-				Object o = vGrid[row][col];
-				buffy.append(' ');
-				if (o == null) {
-					buffy.append('-');
-					//buffy.append(' ');
-				}
-				else {
-					buffy.append('v');
-				}
-				buffy.append(' ');
-			}
-			buffy.append('\n');
-		}
+		String[][] vGrid = new String[height()][width()];
 
+		for (Entry<V, GridPoint> entry : vertexPoints.entrySet()) {
+			V v = entry.getKey();
+			GridPoint p = entry.getValue();
+			vGrid[p.row][p.col] = normalizeVertexName(v.toString());
+		}
+		StringBuilder buffy = new StringBuilder();
+		buffy.append("\n");
+		for (int row = 0; row < vGrid.length; row++) {
+			for (int col = 0; col < vGrid[row].length; col++) {
+				String name = vGrid[row][col];
+				name = name == null ? ".       " : name;
+				buffy.append(name);
+				buffy.append("");
+			}
+			buffy.append("\n");
+		}
 		return buffy.toString();
 	}
 
-	// moves all rows and columns as needed to convert the grid origin to 0,0
-	private static <V, E> void zeroAlignGrid(GridLocationMap<V, E> grid) {
+	private GridLocationMap<V, E> copy() {
+		GridLocationMap<V, E> map = new GridLocationMap<>();
+		map.rootColumn = rootColumn;
 
-		int smallestColumnIndex = 0;
-		int smallestRowIndex = 0;
-		List<Row<V>> rows = grid.rows();
-		for (Row<V> row : rows) {
-			smallestRowIndex = Math.min(smallestRowIndex, row.index);
-			smallestColumnIndex = Math.min(smallestColumnIndex, row.getStartColumn());
+		Set<Entry<V, GridPoint>> entries = vertexPoints.entrySet();
+		for (Entry<V, GridPoint> entry : entries) {
+			map.set(entry.getKey(), new GridPoint(entry.getValue()));
 		}
 
-		int globalColumnOffset = -smallestColumnIndex;
-		int globalRowOffset = -smallestRowIndex;
-
-		for (Row<V> row : rows) {
-
-			List<V> vertices = row.getVertices();
-			for (V v : vertices) {
-				int oldCol = grid.col(v);
-				int oldRow = grid.row(v);
-				int newCol = globalColumnOffset + oldCol;
-				int newRow = globalRowOffset + oldRow;
-				grid.set(v, newRow, newCol);
-			}
+		Set<Entry<E, List<GridPoint>>> edgeEntries = edgePoints.entrySet();
+		for (Entry<E, List<GridPoint>> entry : edgeEntries) {
+			List<GridPoint> points = entry.getValue();
+			List<GridPoint> copy = new ArrayList<>(points.size());
+			points.forEach(p -> copy.add(new GridPoint(p)));
+			map.setArticulations(entry.getKey(), copy);
 		}
+
+		return map;
+	}
+
+	private String normalizeVertexName(String name) {
+		if (name.length() > 8) {
+			return name.substring(0, 8);
+		}
+		return name + "        ".substring(name.length());
+	}
+
+	private Iterable<GridPoint> allPoints() {
+		Stream<GridPoint> vPoints = vertexPoints.values().stream();
+		Stream<GridPoint> ePoints = edgePoints.values().stream().flatMap(l -> l.stream());
+		Stream<GridPoint> streams = Stream.concat(vPoints, ePoints);
+		return () -> streams.iterator();
+	}
+
+	public boolean containsPoint(GridPoint p) {
+		return gridBounds.contains(p);
 	}
 }

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/GridPoint.java

@@ -0,0 +1,64 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph.viewer.layout;
+
+import java.util.Objects;
+
+/**
+ * Row and column information for points in a {@link GridLocationMap}. Using these instead
+ * of java Points, makes the code that translates from grid space to layout space much less
+ * confusing.
+ */
+public class GridPoint {
+
+	public int row;
+	public int col;
+
+	public GridPoint(int row, int col) {
+		this.row = row;
+		this.col = col;
+	}
+
+	public GridPoint(GridPoint point) {
+		this.row = point.row;
+		this.col = point.col;
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(col, row);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null) {
+			return false;
+		}
+		if (getClass() != obj.getClass()) {
+			return false;
+		}
+		GridPoint other = (GridPoint) obj;
+		return col == other.col && row == other.row;
+	}
+
+	@Override
+	public String toString() {
+		return "(r=" + row + ",c=" + col + ")";
+	}
+}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/GridRange.java

@@ -0,0 +1,78 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph.viewer.layout;
+
+import java.util.Objects;
+
+/**
+ * Class for reporting the min/max columns in a row or the min/max rows in a column
+ */
+public class GridRange {
+	public int min;
+	public int max;
+
+	public GridRange() {
+		this(Integer.MAX_VALUE, Integer.MIN_VALUE);
+	}
+
+	public GridRange(int min, int max) {
+		this.min = min;
+		this.max = max;
+	}
+
+	public void add(int value) {
+		min = Math.min(value, min);
+		max = Math.max(value, max);
+	}
+
+	@Override
+	public String toString() {
+		return "[" + min + " -> " + max + "]";
+	}
+
+	public boolean isEmpty() {
+		return min > max;
+	}
+
+	public boolean contains(int value) {
+		return value >= min && value <= max;
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(max, min);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		GridRange other = (GridRange) obj;
+		return max == other.max && min == other.min;
+	}
+
+	public int width() {
+		if (isEmpty()) {
+			return 0;
+		}
+		return max - min + 1;
+	}
+
+}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/LayoutLocationMap.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -15,9 +15,9 @@
  */
 package ghidra.graph.viewer.layout;
 
-import java.awt.*;
+import java.awt.Rectangle;
+import java.awt.Shape;
 import java.util.*;
-import java.util.List;
 import java.util.Map.Entry;
 
 import com.google.common.base.Function;
@@ -43,7 +43,7 @@ public class LayoutLocationMap<V, E> {
 	private int numColumns;
 
 	private TreeMap<Integer, Row<V>> rowsByIndex = new TreeMap<>();
-	private TreeMap<Integer, Column> columnsByIndex = new TreeMap<>();
+	private TreeMap<Integer, Column<V>> columnsByIndex = new TreeMap<>();
 
 	private boolean isCondensed = false;
 	private GridLocationMap<V, E> gridLocations;
@@ -54,29 +54,12 @@ public class LayoutLocationMap<V, E> {
 		this.gridLocations = gridLocations;
 
 		Set<V> vertices = gridLocations.vertices();
-		Set<E> edges = gridLocations.edges();
-		MinMaxRowColumn minMax = getMinMaxRowColumnValues(vertices, edges, monitor);
-		numRows = minMax.maxRow + 1;
-		numColumns = minMax.maxCol + 1;
+		numRows = gridLocations.height();
+		numColumns = gridLocations.width();
 
 		initializeLayoutLocations(transformer, vertices, monitor);
 	}
 
-	private LayoutLocationMap() {
-		// copy constructor
-	}
-
-	public LayoutLocationMap<V, E> copy() {
-		LayoutLocationMap<V, E> map = new LayoutLocationMap<>();
-		map.isCondensed = isCondensed;
-		map.numRows = numRows;
-		map.numColumns = numColumns;
-		map.rowsByIndex = new TreeMap<>(rowsByIndex);
-		map.columnsByIndex = new TreeMap<>(columnsByIndex);
-		map.gridLocations = gridLocations.copy();
-		return map;
-	}
-
 	public void dispose() {
 		rowsByIndex.clear();
 		columnsByIndex.clear();
@@ -90,19 +73,19 @@ public class LayoutLocationMap<V, E> {
 		return numColumns;
 	}
 
-	public Column col(V v) {
+	public Column<V> col(V v) {
 		Integer col = gridLocations.col(v);
 		return doGetColumn(col);
 	}
 
-	public Column col(int gridX) {
+	public Column<V> col(int gridX) {
 		return doGetColumn(gridX);
 	}
 
-	public Column getColumnContaining(int x) {
-		Column column = null;
-		Collection<Column> values = columnsByIndex.values();
-		for (Column nextColumn : values) {
+	public Column<V> getColumnContaining(int x) {
+		Column<V> column = null;
+		Collection<Column<V>> values = columnsByIndex.values();
+		for (Column<V> nextColumn : values) {
 			if (x < nextColumn.x) {
 				return column;
 			}
@@ -111,10 +94,10 @@ public class LayoutLocationMap<V, E> {
 		return column;
 	}
 
-	private Column doGetColumn(int index) {
-		Column column = columnsByIndex.get(index);
+	private Column<V> doGetColumn(int index) {
+		Column<V> column = columnsByIndex.get(index);
 		if (column == null) {
-			column = new Column(index);
+			column = new Column<>(index);
 			columnsByIndex.put(index, column);
 		}
 		return column;
@@ -125,10 +108,10 @@ public class LayoutLocationMap<V, E> {
 	 * 
 	 * @return the columns in this location map, sorted from lowest index to highest
 	 */
-	public Collection<Column> columns() {
-		List<Column> result = new ArrayList<>();
-		Collection<Column> values = columnsByIndex.values();
-		for (Column column : values) {
+	public Collection<Column<V>> columns() {
+		List<Column<V>> result = new ArrayList<>();
+		Collection<Column<V>> values = columnsByIndex.values();
+		for (Column<V> column : values) {
 			result.add(column);
 		}
 		return result;
@@ -148,17 +131,17 @@ public class LayoutLocationMap<V, E> {
 		return results;
 	}
 
-	public Column lastColumn() {
+	public Column<V> lastColumn() {
 
-		Entry<Integer, Column> lastEntry = columnsByIndex.lastEntry();
+		Entry<Integer, Column<V>> lastEntry = columnsByIndex.lastEntry();
 		if (lastEntry == null) {
 			return null;
 		}
 		return lastEntry.getValue();
 	}
 
-	public Column nextColumn(Column column) {
-		Column nextColumn = doGetColumn(column.index + 1);
+	public Column<V> nextColumn(Column<V> column) {
+		Column<V> nextColumn = doGetColumn(column.index + 1);
 		if (!nextColumn.isInitialized()) {
 			// last column?
 			nextColumn.x = column.x + column.getPaddedWidth(isCondensed);
@@ -166,12 +149,12 @@ public class LayoutLocationMap<V, E> {
 		return nextColumn;
 	}
 
-	public List<Point> articulations(E e) {
+	public List<GridPoint> articulations(E e) {
 		return gridLocations.getArticulations(e);
 	}
 
 	public Row<V> row(V v) {
-		Integer row = gridLocations.row(v);
+		int row = gridLocations.row(v);
 		return doGetRow(row);
 	}
 
@@ -215,7 +198,7 @@ public class LayoutLocationMap<V, E> {
 
 	public List<Integer> getColOffsets() {
 		ArrayList<Integer> list = new ArrayList<>();
-		for (Column column : columnsByIndex.values()) {
+		for (Column<V> column : columnsByIndex.values()) {
 			list.add(column.x);
 		}
 		return list;
@@ -231,70 +214,55 @@ public class LayoutLocationMap<V, E> {
 			columnsByIndex + "]";
 	}
 
+	public GridCoordinates getGridCoordinates() {
+		Row<?> lastRow = lastRow();
+		Column<?> lastColumn = lastColumn();
+		if (lastRow == null || lastColumn == null) {
+			return new GridCoordinates(new int[0], new int[0]);
+		}
+
+		// add 1 to compute a row y value and a column x value for closing the grid
+		int[] rowStarts = new int[lastRow.index + 1];
+		int[] colStarts = new int[lastColumn.index + 1];
+
+		for (Row<?> row : rowsByIndex.values()) {
+			rowStarts[row.index] = row.y;
+		}
+		for (Column<?> col : columnsByIndex.values()) {
+			colStarts[col.index] = col.x;
+		}
+
+		// Give any empty rows or columns the coordinate of the row or column that precedes it 
+		// since it takes no space. (Otherwise all the empty row or column labels would overwrite
+		// themselves at the 0 row or 0 column.
+		for (int row = 1; row < rowStarts.length; row++) {
+			if (rowStarts[row] == 0) {
+				rowStarts[row] = rowStarts[row - 1];
+			}
+		}
+		for (int col = 1; col < colStarts.length; col++) {
+			if (colStarts[col] == 0) {
+				colStarts[col] = colStarts[col - 1];
+			}
+		}
+
+		// close the grid
+		rowStarts[rowStarts.length - 1] = lastRow.y + lastRow.getPaddedHeight(isCondensed);
+		colStarts[colStarts.length - 1] = lastColumn.x + lastColumn.getPaddedWidth(isCondensed);
+
+		return new GridCoordinates(rowStarts, colStarts);
+
+	}
+
 //==================================================================================================
 // Initialization Code
 //==================================================================================================
 
-	private MinMaxRowColumn getMinMaxRowColumnValues(Collection<V> vertices, Collection<E> edges,
-			TaskMonitor monitor) throws CancelledException {
-
-		MinMaxRowColumn minMax = new MinMaxRowColumn();
-
-		for (V v : vertices) {
-			monitor.checkCancelled();
-
-			int row = gridLocations.row(v);
-			if (row > minMax.maxRow) {
-				minMax.maxRow = row;
-			}
-			if (row < minMax.minRow) {
-				minMax.minRow = row;
-			}
-
-			int column = gridLocations.col(v);
-			if (column > minMax.maxCol) {
-				minMax.maxCol = column;
-			}
-			if (column < minMax.minCol) {
-				minMax.minCol = column;
-			}
-		}
-
-		for (E edge : edges) {
-			monitor.checkCancelled();
-
-			List<Point> articulations = gridLocations.getArticulations(edge);
-			if (articulations.isEmpty()) {
-				continue;
-			}
-
-			for (Point location : articulations) {
-				int row = location.y;
-				if (row > minMax.maxRow) {
-					minMax.maxRow = row;
-				}
-				if (row < minMax.minRow) {
-					minMax.minRow = row;
-				}
-
-				int column = location.x;
-				if (column > minMax.maxCol) {
-					minMax.maxCol = column;
-				}
-				if (column < minMax.minCol) {
-					minMax.minCol = column;
-				}
-			}
-		}
-
-		return minMax;
-	}
-
 	private void initializeLayoutLocations(Function<V, Shape> transformer, Collection<V> vertices,
 			TaskMonitor monitor) throws CancelledException {
 
 		// create this class's rows from the grid
-		List<Row<V>> gridRows = gridLocations.rows();
+		Collection<Row<V>> gridRows = gridLocations.rowsMap().values();
 		for (Row<V> row : gridRows) {
 			rowsByIndex.put(row.index, row);
 		}
@@ -308,7 +276,7 @@ public class LayoutLocationMap<V, E> {
 			monitor.checkCancelled();
 
 			Row<V> row = row(vertex);
-			Column column = col(vertex);
+			Column<V> column = col(vertex);
 			Shape shape = transformer.apply(vertex);
 			Rectangle bounds = shape.getBounds();
 			if (bounds.width > column.width) {
@@ -349,7 +317,7 @@ public class LayoutLocationMap<V, E> {
 		for (int i = 0; i < n; i++) {
 			monitor.checkCancelled();
 
-			Column column = col(i);
+			Column<V> column = col(i);
 			column.x = offset;
 			offset += column.getPaddedWidth(isCondensed);
 		}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/MinMaxRowColumn.java

@@ -1,23 +0,0 @@
-/* ###
- * IP: GHIDRA
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * 
- *      http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package ghidra.graph.viewer.layout;
-
-public class MinMaxRowColumn {
-	public int minRow = Integer.MAX_VALUE;
-	public int maxRow = -1;
-	public int minCol = Integer.MAX_VALUE;
-	public int maxCol = -1;
-}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/layout/Row.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -29,7 +29,7 @@ import ghidra.graph.viewer.GraphViewerUtils;
  * of a grid.
  * 
  * <p>This class maintains a collection of vertices on this row, organized by column index.  You
- * can get the column of a vertex from {@link #getColumn(Object) getColumn(V)}.
+ * can get the column of a vertex from {@link #getColumn(Object)}
  * 
  * @param <V> the vertex type
  */
@@ -42,7 +42,7 @@ public class Row<V> {
 	/** The grid index of this row (0, 1...n) for the number of rows */
 	public int index = Integer.MAX_VALUE;
 
-	// Note: this must change together (they are effectively a BiDi map)
+	// Note: these must change together (they are effectively a BiDi map)
 	private TreeMap<Integer, V> verticesByColumn = new TreeMap<>();
 	private Map<V, Integer> columnsByVertex = new HashMap<>();
 

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/renderer/GridPainter.java

@@ -0,0 +1,101 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph.viewer.renderer;
+
+import java.awt.Color;
+import java.awt.Rectangle;
+import java.awt.geom.Point2D;
+
+import edu.uci.ics.jung.algorithms.layout.Layout;
+import edu.uci.ics.jung.visualization.*;
+import edu.uci.ics.jung.visualization.transform.shape.GraphicsDecorator;
+import generic.theme.GThemeDefaults.Colors.Palette;
+import ghidra.graph.viewer.layout.GridCoordinates;
+
+/**
+ * Class for painting the underlying grid used to layout a graph. Used as a visual aid when 
+ * debugging grid based graph layouts.
+ */
+public class GridPainter {
+
+	private GridCoordinates grid;
+
+	public GridPainter(GridCoordinates gridCoordinates) {
+		this.grid = gridCoordinates;
+	}
+
+	public void paintLayoutGridCells(RenderContext<?, ?> renderContext, Layout<?, ?> layout) {
+
+		if (grid == null) {
+			return;
+		}
+		int rowCount = grid.rowCount();
+		int colCount = grid.columnCount();
+
+		GraphicsDecorator g = renderContext.getGraphicsContext();
+		Color originalColor = g.getColor();
+		Color gridColor = Palette.ORANGE;
+		Color textColor = Palette.BLACK;
+
+		Rectangle bounds = grid.getBounds();
+		int width = bounds.width;
+		int height = bounds.height;
+
+		MultiLayerTransformer transformer = renderContext.getMultiLayerTransformer();
+		int previous = -1;
+		for (int row = 0; row < rowCount; row++) {
+			int y = grid.y(row);
+			if (y == previous) {
+				continue; 		// don't paint empty rows
+			}
+			previous = y;
+			Point2D start = new Point2D.Double(0, y);
+			Point2D end = new Point2D.Double(width, y);
+			start = transformer.transform(Layer.LAYOUT, start);
+			end = transformer.transform(Layer.LAYOUT, end);
+
+			g.setColor(textColor);
+			g.drawString(Integer.toString(row), (float) start.getX() - 20,
+				(float) (start.getY() + 5));
+
+			g.setColor(gridColor);
+			g.drawLine((int) start.getX(), (int) start.getY(), (int) end.getX(), (int) end.getY());
+		}
+
+		previous = -1;
+		for (int col = 0; col < colCount; col++) {
+			int x = grid.x(col);
+			if (x == previous) {
+				continue;
+			}
+			previous = x;
+			Point2D start = new Point2D.Double(x, 0);
+			Point2D end = new Point2D.Double(x, height);
+			start = transformer.transform(Layer.LAYOUT, start);
+			end = transformer.transform(Layer.LAYOUT, end);
+
+			g.setColor(textColor);
+			g.drawString(Integer.toString(col), (float) start.getX() - 5,
+				(float) (start.getY() - 10));
+
+			g.setColor(gridColor);
+			g.drawLine((int) start.getX(), (int) start.getY(), (int) end.getX(), (int) end.getY());
+		}
+
+		g.setColor(originalColor);
+	}
+
+}

Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/renderer/VisualGraphRenderer.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -15,21 +15,15 @@
  */
 package ghidra.graph.viewer.renderer;
 
-import java.awt.Color;
-import java.awt.geom.Point2D;
 import java.util.*;
 
 import com.google.common.base.Function;
 
 import edu.uci.ics.jung.algorithms.layout.Layout;
-import edu.uci.ics.jung.visualization.*;
-import edu.uci.ics.jung.visualization.layout.ObservableCachingLayout;
+import edu.uci.ics.jung.visualization.RenderContext;
 import edu.uci.ics.jung.visualization.renderers.Renderer;
-import edu.uci.ics.jung.visualization.transform.shape.GraphicsDecorator;
-import generic.theme.GThemeDefaults.Colors.Palette;
 import ghidra.graph.viewer.*;
 import ghidra.graph.viewer.edge.BasicEdgeLabelRenderer;
-import ghidra.graph.viewer.layout.*;
 
 /**
  * This was created to add the ability to paint selected vertices above other vertices.  We need
@@ -42,11 +36,16 @@ import ghidra.graph.viewer.layout.*;
 public class VisualGraphRenderer<V extends VisualVertex, E extends VisualEdge<V>>
 		extends edu.uci.ics.jung.visualization.renderers.BasicRenderer<V, E> {
 
+	private static GridPainter gridPainter;
+
 	/**
-	 * Used for displaying grid information for graph layouts
+	 * Sets a painter to show an underlying grid. (To see a layout's associated grid, search
+	 * for calls to this method and un-comment them)
+	 * @param gridPainter A painter that paints the grid that a layout was based on.
 	 */
-	public static Map<VisualGraphLayout<?, ?>, LayoutLocationMap<?, ?>> DEBUG_ROW_COL_MAP =
-		new HashMap<>();
+	public static void setGridPainter(GridPainter gridPainter) {
+		VisualGraphRenderer.gridPainter = gridPainter;
+	}
 
 	private Renderer.EdgeLabel<V, E> edgeLabelRenderer = new BasicEdgeLabelRenderer<>();
 
@@ -73,6 +72,9 @@ public class VisualGraphRenderer<V extends VisualVertex, E extends VisualEdge<V>
 	private void mimickSuperPaintingWithoutPaintingSelectedVertices(
 			RenderContext<V, E> renderContext, Layout<V, E> layout) {
 
+		if (gridPainter != null) {
+			gridPainter.paintLayoutGridCells(renderContext, layout);
+		}
 		for (E e : layout.getGraph().getEdges()) {
 
 			renderEdge(renderContext, layout, e);
@@ -94,7 +96,6 @@ public class VisualGraphRenderer<V extends VisualVertex, E extends VisualEdge<V>
 //			renderEdgeLabel(renderContext, layout, e);
 //		}
 
-		paintLayoutGridCells(renderContext, layout);
 	}
 
 	@Override
@@ -124,81 +125,4 @@ public class VisualGraphRenderer<V extends VisualVertex, E extends VisualEdge<V>
 		edgeLabelRenderer.labelEdge(rc, layout, e, xform.apply(e));
 	}
 
-	@SuppressWarnings({ "unchecked", "rawtypes" }) // the types in the cast matter not
-	private void paintLayoutGridCells(RenderContext<V, E> renderContext, Layout<V, E> layout) {
-
-		// to enable this debug, search java files for commented-out uses of 'DEBUG_ROW_COL_MAP'
-		Layout<V, E> key = layout;
-		if (layout instanceof ObservableCachingLayout) {
-			key = ((ObservableCachingLayout) layout).getDelegate();
-		}
-		LayoutLocationMap<?, ?> locationMap = DEBUG_ROW_COL_MAP.get(key);
-		if (locationMap == null) {
-			return;
-		}
-
-		int rowCount = locationMap.getRowCount();
-		if (rowCount == 0) {
-			return; // ?
-		}
-
-		GraphicsDecorator g = renderContext.getGraphicsContext();
-		Color originalColor = g.getColor();
-		Color gridColor = Palette.ORANGE;
-		Color textColor = Palette.BLACK;
-
-		boolean isCondensed = locationMap.isCondensed();
-		Row<?> lastRow = locationMap.lastRow();
-		Column lastColumn = locationMap.lastColumn();
-
-		if (lastRow == null || lastColumn == null) {
-			return; // empty graph?
-		}
-
-		int width = lastColumn.x + lastColumn.getPaddedWidth(isCondensed);
-		int height = lastRow.y + lastRow.getPaddedHeight(isCondensed);
-
-		MultiLayerTransformer transformer = renderContext.getMultiLayerTransformer();
-		for (Row<?> row : locationMap.rows()) {
-			Point2D start = new Point2D.Double(0, row.y);
-			start = transformer.transform(Layer.LAYOUT, start);
-			g.setColor(textColor);
-			g.drawString(Integer.toString(row.index), (float) start.getX() - 20,
-				(float) (start.getY() + 5));
-
-			Point2D end = new Point2D.Double(width, row.y);
-			end = transformer.transform(Layer.LAYOUT, end);
-			g.setColor(gridColor);
-			g.drawLine((int) start.getX(), (int) start.getY(), (int) end.getX(), (int) end.getY());
-		}
-
-		// close the grid
-		Point2D start = new Point2D.Double(0, lastRow.y + lastRow.getPaddedHeight(isCondensed));
-		start = transformer.transform(Layer.LAYOUT, start);
-		Point2D end = new Point2D.Double(width, lastRow.y + lastRow.getPaddedHeight(isCondensed));
-		end = transformer.transform(Layer.LAYOUT, end);
-		g.drawLine((int) start.getX(), (int) start.getY(), (int) end.getX(), (int) end.getY());
-
-		for (Column column : locationMap.columns()) {
-			start = new Point2D.Double(column.x, 0);
-			start = transformer.transform(Layer.LAYOUT, start);
-			g.setColor(textColor);
-			g.drawString(Integer.toString(column.index), (float) start.getX() - 5,
-				(float) (start.getY() - 10));
-
-			end = new Point2D.Double(column.x, height);
-			end = transformer.transform(Layer.LAYOUT, end);
-			g.setColor(gridColor);
-			g.drawLine((int) start.getX(), (int) start.getY(), (int) end.getX(), (int) end.getY());
-		}
-
-		// close the grid
-		start = new Point2D.Double(lastColumn.x + lastColumn.getPaddedWidth(isCondensed), 0);
-		start = transformer.transform(Layer.LAYOUT, start);
-		end = new Point2D.Double(lastColumn.x + lastColumn.getPaddedWidth(isCondensed), height);
-		end = transformer.transform(Layer.LAYOUT, end);
-		g.drawLine((int) start.getX(), (int) start.getY(), (int) end.getX(), (int) end.getY());
-
-		g.setColor(originalColor);
-	}
 }

Ghidra/Framework/Graph/src/test.slow/java/ghidra/graph/viewer/AbstractVisualGraphTest.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -34,10 +34,12 @@ import docking.test.AbstractDockingTest;
 import edu.uci.ics.jung.algorithms.layout.Layout;
 import ghidra.graph.graphs.AbstractTestVertex;
 import ghidra.graph.graphs.TestEdge;
-import ghidra.graph.support.*;
+import ghidra.graph.support.TestLayoutProvider;
+import ghidra.graph.support.TestVisualGraph;
 import ghidra.graph.viewer.event.mouse.VisualGraphMouseTrackingGraphMousePlugin;
 import ghidra.graph.viewer.event.mouse.VisualGraphPluggableGraphMouse;
 import ghidra.graph.viewer.event.picking.GPickedState;
+import ghidra.graph.viewer.layout.VisualGraphLayout;
 import ghidra.util.Msg;
 import ghidra.util.exception.CancelledException;
 import ghidra.util.task.TaskMonitor;
@@ -73,7 +75,6 @@ public abstract class AbstractVisualGraphTest extends AbstractDockingTest {
 	protected void buildAndLayoutGraph() throws CancelledException {
 		// the test machine has odd Swing exceptions when we construct UIs off the Swing thread
 		graph = runSwing(() -> buildGraph());
-
 		TestLayoutProvider layoutProvider = createLayoutProvider();
 		graph.setLayout(layoutProvider.getLayout(graph, TaskMonitor.DUMMY));
 		graphComponent = runSwing(() -> createGraphComponent(layoutProvider));
@@ -190,7 +191,7 @@ public abstract class AbstractVisualGraphTest extends AbstractDockingTest {
 			GraphViewerUtils.translatePointFromViewSpaceToLayoutSpace(viewPoint, viewer);
 
 		swing(() -> {
-			TestGraphLayout layout = graph.getLayout();
+			VisualGraphLayout<AbstractTestVertex, TestEdge> layout = graph.getLayout();
 			Point2D p = layout.apply(v);
 			layout.setLocation(v,
 				new Point2D.Double(p.getX() + layoutPoint.getX(), p.getY() + layoutPoint.getY()));

Ghidra/Framework/Graph/src/test.slow/java/ghidra/graph/viewer/GraphViewerTest.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -26,12 +26,11 @@ import java.util.List;
 
 import org.junit.Test;
 
-import edu.uci.ics.jung.algorithms.layout.KKLayout;
-import edu.uci.ics.jung.algorithms.layout.Layout;
 import generic.test.AbstractGTest;
 import ghidra.graph.graphs.*;
-import ghidra.graph.support.*;
+import ghidra.graph.support.TestVertexTooltipProvider;
 import ghidra.graph.support.TestVertexTooltipProvider.SpyTooltip;
+import ghidra.graph.support.TestVisualGraph;
 
 public class GraphViewerTest extends AbstractVisualGraphTest {
 
@@ -53,16 +52,6 @@ public class GraphViewerTest extends AbstractVisualGraphTest {
 		return g;
 	}
 
-	@Override
-	protected TestLayoutProvider createLayoutProvider() {
-		return new TestLayoutProvider() {
-			@Override
-			protected Layout<AbstractTestVertex, TestEdge> createJungLayout(TestVisualGraph g) {
-				return new KKLayout<>(g);
-			}
-		};
-	}
-
 	@Override
 	protected void initialize() {
 		viewer = graphComponent.getPrimaryViewer();

Ghidra/Framework/Graph/src/test/java/ghidra/graph/AbstractGraphAlgorithmsTest.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -77,10 +77,10 @@ public abstract class AbstractGraphAlgorithmsTest extends AbstractGenericTest {
 	protected TestV[] generateSimplyConnectedGraph(int nVertices) {
 		TestV[] vertices = new TestV[nVertices];
 		for (int i = 0; i < nVertices; i++) {
-			vertices[i] = vertex(i);
+			vertices[i] = v(i);
 		}
 		for (int i = 0; i < nVertices - 1; i++) {
-			edge(vertices[i], vertices[i + 1]);
+			e(vertices[i], vertices[i + 1]);
 		}
 		return vertices;
 	}
@@ -88,12 +88,12 @@ public abstract class AbstractGraphAlgorithmsTest extends AbstractGenericTest {
 	protected TestV[] generateCompletelyConnectedGraph(int nVertices) {
 		TestV[] vertices = new TestV[nVertices];
 		for (int i = 0; i < nVertices; i++) {
-			vertices[i] = vertex(i);
+			vertices[i] = v(i);
 		}
 		for (int i = 0; i < nVertices; i++) {
 			for (int j = 0; j < nVertices; j++) {
 				if (i != j) {
-					edge(vertices[i], vertices[j]);
+					e(vertices[i], vertices[j]);
 				}
 			}
 		}
@@ -103,12 +103,12 @@ public abstract class AbstractGraphAlgorithmsTest extends AbstractGenericTest {
 	protected TestV[] generateHalflyConnectedGraph(int nVertices) {
 		TestV[] vertices = new TestV[nVertices];
 		for (int i = 0; i < nVertices; i++) {
-			vertices[i] = vertex(i);
+			vertices[i] = v(i);
 		}
 
 		// at least one straight line through the graph
 		for (int i = 0; i < nVertices - 1; i++) {
-			edge(vertices[i], vertices[i + 1]);
+			e(vertices[i], vertices[i + 1]);
 		}
 
 		// extra connections
@@ -116,7 +116,7 @@ public abstract class AbstractGraphAlgorithmsTest extends AbstractGenericTest {
 		for (int i = 0; i < nVertices; i++) {
 			for (int j = 0; j < n; j++) {
 				if (i != j) {
-					edge(vertices[i], vertices[j]);
+					e(vertices[i], vertices[j]);
 				}
 			}
 		}
@@ -126,12 +126,12 @@ public abstract class AbstractGraphAlgorithmsTest extends AbstractGenericTest {
 	protected TestV[] generateHalflyConnectedGraphNoBacktracking(int nVertices) {
 		TestV[] vertices = new TestV[nVertices];
 		for (int i = 0; i < nVertices; i++) {
-			vertices[i] = vertex(i);
+			vertices[i] = v(i);
 		}
 
 		// at least one straight line through the graph
 		for (int i = 0; i < nVertices - 1; i++) {
-			edge(vertices[i], vertices[i + 1]);
+			e(vertices[i], vertices[i + 1]);
 		}
 
 		// extra connections
@@ -139,7 +139,7 @@ public abstract class AbstractGraphAlgorithmsTest extends AbstractGenericTest {
 		for (int i = 0; i < nVertices; i++) {
 			for (int j = i; j < n; j++) {
 				if (i != j) {
-					edge(vertices[i], vertices[j]);
+					e(vertices[i], vertices[j]);
 				}
 			}
 		}
@@ -165,15 +165,15 @@ public abstract class AbstractGraphAlgorithmsTest extends AbstractGenericTest {
 		Assert.fail("Unexpected set size");
 	}
 
-	protected TestV vertex(int id) {
+	protected TestV v(int id) {
 		return new TestV(id);
 	}
 
-	protected TestV vertex(String id) {
+	protected TestV v(String id) {
 		return new TestV(id);
 	}
 
-	protected TestE edge(TestV start, TestV end) {
+	protected TestE e(TestV start, TestV end) {
 		TestE e = new TestE(start, end);
 		g.addEdge(e);
 		return e;

Ghidra/Framework/Graph/src/test/java/ghidra/graph/GraphAlgorithmsVisualDebugger.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -88,34 +88,34 @@ public class GraphAlgorithmsVisualDebugger extends AbstractGraphAlgorithmsTest {
 			Paths: v1, v3, v5, v10
 		*/
 
-		TestV v1 = vertex(1);
-		TestV v2 = vertex(2);
-		TestV v3 = vertex(3);
-		TestV v4 = vertex(4);
-		TestV v5 = vertex(5);
-		TestV v6 = vertex(6);
-		TestV v7 = vertex(7);
-		TestV v8 = vertex(8);
-		TestV v9 = vertex(9);
-		TestV v10 = vertex(10);
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+		TestV v7 = v(7);
+		TestV v8 = v(8);
+		TestV v9 = v(9);
+		TestV v10 = v(10);
 
-		edge(v1, v2);
-		edge(v1, v3);
+		e(v1, v2);
+		e(v1, v3);
 
-		edge(v2, v1); // back edge
+		e(v2, v1); // back edge
 
-		edge(v3, v4);
-		edge(v3, v5);
-		edge(v3, v6);
+		e(v3, v4);
+		e(v3, v5);
+		e(v3, v6);
 
-		edge(v5, v10);
+		e(v5, v10);
 
-		edge(v6, v7);
+		e(v6, v7);
 
-		edge(v7, v8);
-		edge(v7, v9);
+		e(v7, v8);
+		e(v7, v9);
 
-		edge(v9, v6); // back edge
+		e(v9, v6); // back edge
 
 		AlgorithmSteppingTaskMonitor steppingMonitor = new AlgorithmSteppingTaskMonitor();
 		steppingMonitor = new AlgorithmSelfSteppingTaskMonitor(500);

Ghidra/Framework/Graph/src/test/java/ghidra/graph/GraphToTreeTest.java

@@ -0,0 +1,242 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph;
+
+import static org.junit.Assert.*;
+
+import java.util.*;
+
+import org.junit.Test;
+
+public class GraphToTreeTest extends AbstractGraphAlgorithmsTest {
+	private Comparator<TestE> edgeComparator = (e1, e2) -> e1.toString().compareTo(e2.toString());
+
+	@Override
+	protected GDirectedGraph<TestV, TestE> createGraph() {
+		return GraphFactory.createDirectedGraph();
+	}
+
+	@Test
+	public void testSimpleGraph() {
+		//   v1 -> v2 -> v3
+		//    |
+		//   v4 -> v5 -> v6
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+		e(v1, v2);
+		e(v2, v3);
+		e(v1, v4);
+		e(v4, v5);
+		e(v5, v6);
+
+		//  expected same graph
+		//   v1 -> v2 -> v3
+		//    |
+		//   v4 -> v5 -> v6
+
+		GDirectedGraph<TestV, TestE> tree = GraphAlgorithms.toTree(g, v1, edgeComparator);
+		assertEdges(tree, e(v1, v2), e(v2, v3), e(v1, v4), e(v4, v5), e(v5, v6));
+	}
+
+	@Test
+	public void testGraphWithLoop() {
+		//   v1 -> v2 -> v3 <----
+		//    |	                 |
+		//   v4 -> v5 -> v6      |
+		//    |                  |
+		//    |->---->----->-----|
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+
+		e(v1, v2);
+		e(v2, v3);
+		e(v1, v4);
+		e(v4, v5);
+		e(v5, v6);
+		e(v4, v3);
+
+		// expected:
+		//   v1 -> v2 -> v3
+		//    |	                 
+		//   v4 -> v5 -> v6 
+
+		GDirectedGraph<TestV, TestE> tree = GraphAlgorithms.toTree(g, v1, edgeComparator);
+		assertEdges(tree, e(v1, v2), e(v2, v3), e(v1, v4), e(v4, v5), e(v5, v6));
+
+	}
+
+	@Test
+	public void testDoubleLoop() {
+		//   V1 <- V4 <--------
+		//    |     ^          ^
+		//    v     |          |
+		//   V2 -> V3 -> V5 -> V6
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+
+		e(v1, v2);
+		e(v2, v3);
+		e(v3, v4);
+		e(v3, v5);
+		e(v5, v6);
+		e(v6, v4);
+		e(v4, v1);
+
+		// expected:
+		//
+		//   V1 -> V2 -> V3 -> V5 -> V6  -> V4 
+
+		GDirectedGraph<TestV, TestE> tree = GraphAlgorithms.toTree(g, v1, edgeComparator);
+		assertEdges(tree, e(v1, v2), e(v2, v3), e(v3, v5), e(v5, v6), e(v6, v4));
+	}
+
+	@Test
+	public void testInterleavedBranching() {
+
+		/*
+		 	 .<-v1->.
+		 	 |   |  |
+		 	 |  v4  |
+		 	 |   |  |
+		 	 >--v3  |
+		 		 |  |
+		 		v2--<
+		 */
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+
+		e(v1, v3);
+		e(v1, v4);
+		e(v1, v2);
+		e(v4, v3);
+		e(v3, v2);
+
+		// expected:
+		// v1-> v4 -> v3 -> v2
+
+		GDirectedGraph<TestV, TestE> tree = GraphAlgorithms.toTree(g, v1, edgeComparator);
+		assertEdges(tree, e(v1, v4), e(v4, v3), e(v3, v2));
+	}
+
+	@Test
+	public void testMixedGraph() {
+
+		//@formatter:off
+		/*
+				v1
+			 	 |
+				v2
+			 	 |
+	sink   v3 <- v4
+		   /\	 |
+		   	|	 v5
+			| 	/  \
+			| v6   v7
+		    |  |\   |
+		    | v8  \ |
+		    |   \   |
+		    |     \ |
+		    |      v9
+			|	   / \
+		    |     /   \
+		    .<--v11-->v10	sink
+
+		*/
+		//@formatter:on
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+		TestV v7 = v(7);
+		TestV v8 = v(8);
+		TestV v9 = v(9);
+		TestV v10 = v(10);
+		TestV v11 = v(11);
+
+		e(v1, v2);
+		e(v2, v4);
+		e(v4, v3);
+		e(v4, v5);
+
+		e(v5, v6);
+		e(v5, v7);
+		e(v6, v8);
+		e(v6, v9);
+		e(v7, v9);
+		e(v8, v9);
+		e(v9, v10);
+		e(v9, v11);
+		e(v11, v3);
+		e(v11, v10);
+
+		//@formatter:off
+		/* expected
+		 
+				v1
+			 	 |
+				v2
+			 	 |
+	sink        v4
+		     	 |
+		   		 v5
+			 	/  \
+		   	  v6   v7
+		       |   
+		      v8   
+		       |
+		      v9
+		       |
+		      v11-->v10
+			   |
+			  v3 
+		*/
+		//@formatter:on
+
+		GDirectedGraph<TestV, TestE> tree = GraphAlgorithms.toTree(g, v1, edgeComparator);
+		assertEdges(tree, e(v1, v2), e(v2, v4), e(v4, v5), e(v5, v6),
+			e(v5, v7), e(v6, v8), e(v8, v9), e(v9, v11), e(v11, v10), e(v11, v3));
+	}
+
+	private void assertEdges(GDirectedGraph<TestV, TestE> tree, TestE... edges) {
+		Set<TestE> allEdges = new HashSet<>(tree.getEdges());
+		assertEquals("edge count: ", edges.length, allEdges.size());
+		for (TestE edge : edges) {
+			if (!allEdges.contains(edge)) {
+				fail("Missing expected edge: " + edge);
+			}
+		}
+	}
+}

Ghidra/Framework/Graph/src/test/java/ghidra/graph/MutableGDirectedGraphWrapperTest.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -58,25 +58,25 @@ public class MutableGDirectedGraphWrapperTest extends AbstractGraphAlgorithmsTes
 				 	    v6		 	   
 		 */
 
-		TestV v1 = vertex(1);  // Root
-		TestV v2 = vertex(2);  // Root
-		TestV v3 = vertex(3);
-		TestV v4 = vertex(4);
-		TestV v5 = vertex(5);
-		TestV v6 = vertex(6);
+		TestV v1 = v(1);  // Root
+		TestV v2 = v(2);  // Root
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
 
-		TestE e1 = edge(v1, v3);
-		TestE e2 = edge(v3, v5);
-		TestE e3 = edge(v5, v6);
+		TestE e1 = e(v1, v3);
+		TestE e2 = e(v3, v5);
+		TestE e3 = e(v5, v6);
 
-		TestE e4 = edge(v2, v4);
-		TestE e5 = edge(v4, v6);
+		TestE e4 = e(v2, v4);
+		TestE e5 = e(v4, v6);
 
 		//
 		// Now create the second graph above using a mutable wrapper
 		//
 		MutableGDirectedGraphWrapper<TestV, TestE> wrapper = new MutableGDirectedGraphWrapper<>(g);
-		TestV fakeRoot = vertex("Fake Root");
+		TestV fakeRoot = v("Fake Root");
 		TestE fakeEdge1 = new TestE(fakeRoot, v1);
 		TestE fakeEdge2 = new TestE(fakeRoot, v2);
 

Ghidra/Framework/Graph/src/test/java/ghidra/graph/TopologicalGraphSortTest.java

@@ -0,0 +1,212 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.graph;
+
+import static org.junit.Assert.*;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+import org.junit.Test;
+
+public class TopologicalGraphSortTest extends AbstractGraphAlgorithmsTest {
+	private Comparator<TestE> edgeComparator = (e1, e2) -> e1.toString().compareTo(e2.toString());
+
+	@Override
+	protected GDirectedGraph<TestV, TestE> createGraph() {
+		return GraphFactory.createDirectedGraph();
+	}
+
+	@Test
+	public void testSimpleGraph() {
+		//   v1 -> v2 -> v3
+		//    |
+		//   v4 -> v5 -> v6
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+		e(v1, v2);
+		e(v2, v3);
+		e(v1, v4);
+		e(v4, v5);
+		e(v5, v6);
+
+		List<TestV> sorted = GraphAlgorithms.topologicalSort(g, v1, edgeComparator);
+		assertList(sorted, v1, v2, v3, v4, v5, v6);
+	}
+
+	@Test
+	public void testGraphWithLoop() {
+		//   v1 -> v2 -> v3 <----
+		//    |	                 |
+		//   v4 -> v5 -> v6      |
+		//    |                  |
+		//    |->---->----->-----|
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+
+		e(v1, v2);
+		e(v2, v3);
+		e(v1, v4);
+		e(v4, v5);
+		e(v5, v6);
+		e(v4, v3);
+
+		List<TestV> sorted = GraphAlgorithms.topologicalSort(g, v1, edgeComparator);
+		assertList(sorted, v1, v2, v4, v3, v5, v6);
+
+	}
+
+	@Test
+	public void testDoubleLoop() {
+		//   V1 <- V4 <--------
+		//    |     ^          ^
+		//    v     |          |
+		//   V2 -> V3 -> V5 -> V6
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+
+		e(v1, v2);
+		e(v2, v3);
+		e(v3, v4);
+		e(v3, v5);
+		e(v5, v6);
+		e(v6, v4);
+		e(v4, v1);
+
+		List<TestV> sorted = GraphAlgorithms.topologicalSort(g, v1, edgeComparator);
+		assertList(sorted, v1, v2, v3, v5, v6, v4);
+	}
+
+	@Test
+	public void testInterleavedBranching() {
+
+		/*
+		 	 .<-v1->.
+		 	 |   |  |
+		 	 |  v4  |
+		 	 |   |  |
+		 	 >--v3  |
+		 		 |  |
+		 		v2--<
+		 */
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+
+		e(v1, v3);
+		e(v1, v4);
+		e(v1, v2);
+		e(v4, v3);
+		e(v3, v2);
+
+		List<TestV> sorted = GraphAlgorithms.topologicalSort(g, v1, edgeComparator);
+		assertList(sorted, v1, v4, v3, v2);
+	}
+
+	@Test
+	public void testMixedGraph() {
+
+		//@formatter:off
+		/*
+				v1
+			 	 |
+				v2
+			 	 |
+	sink   v3 <- v4
+		   /\	 |
+		   	|	 v5
+			| 	/  \
+			| v6   v7
+		    |  |\   |
+		    | v8  \ |
+		    |   \   |
+		    |     \ |
+		    |      v9
+			|	   / \
+		    |     /   \
+		    .<--v11-->v10	sink
+
+		*/
+		//@formatter:on
+
+		TestV v1 = v(1);
+		TestV v2 = v(2);
+		TestV v3 = v(3);
+		TestV v4 = v(4);
+		TestV v5 = v(5);
+		TestV v6 = v(6);
+		TestV v7 = v(7);
+		TestV v8 = v(8);
+		TestV v9 = v(9);
+		TestV v10 = v(10);
+		TestV v11 = v(11);
+
+		e(v1, v2);
+		e(v2, v4);
+		e(v4, v3);
+		e(v4, v5);
+
+		e(v5, v6);
+		e(v5, v7);
+		e(v6, v8);
+		e(v6, v9);
+		e(v7, v9);
+		e(v8, v9);
+		e(v9, v10);
+		e(v9, v11);
+		e(v11, v3);
+		e(v11, v10);
+
+		List<TestV> sorted = GraphAlgorithms.topologicalSort(g, v1, edgeComparator);
+		assertList(sorted, v1, v2, v4, v5, v6, v8, v7, v9, v11, v10, v3);
+
+	}
+
+	private void assertList(List<TestV> sorted, TestV... vertices) {
+		if (vertices.length != sorted.size()) {
+			failed(sorted, vertices);
+		}
+		assertEquals(vertices.length, sorted.size());
+		for (int i = 0; i < vertices.length; i++) {
+			if (vertices[i] != sorted.get(i)) {
+				failed(sorted, vertices);
+			}
+		}
+	}
+
+	private void failed(List<TestV> sorted, TestV[] vertices) {
+		String expected =
+			Arrays.stream(vertices).map(v -> v.toString()).collect(Collectors.joining(", "));
+		String actual = sorted.stream().map(v -> v.toString()).collect(Collectors.joining(", "));
+		fail("expected: \"" + expected + "\", but got: \"" + actual + "\"");
+	}
+}

Ghidra/Framework/Graph/src/test/java/ghidra/graph/algo/viewer/TestGraphAlgorithmSteppingViewerPanel.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -314,13 +314,10 @@ public class TestGraphAlgorithmSteppingViewerPanel<V, E extends GEdge<V>> extend
 				GridLocationMap<AlgorithmTestSteppingVertex<V>, AlgorithmTestSteppingEdge<V>> grid,
 				int row, int col) {
 
-			int existing = grid.row(v);
-			if (existing > 0) {
-				return; // already processed
+			if (grid.containsVertex(v)) {
+				return;
 			}
-
-			grid.row(v, row);
-			grid.col(v, col);
+			grid.set(v, row, col);
 			int nextRow = row++;
 
 			Collection<AlgorithmTestSteppingEdge<V>> children = g.getOutEdges(v);

Ghidra/Framework/Graph/src/test/java/ghidra/graph/graphs/LabelTestVertex.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -27,20 +27,23 @@ import generic.theme.GThemeDefaults.Colors.Palette;
  */
 public class LabelTestVertex extends AbstractTestVertex {
 
-	private JLabel label = new GDLabel();
+	private JLabel label;
 
 	public LabelTestVertex(String name) {
 		super(name);
-		label.setText(name);
-		label.setPreferredSize(new Dimension(50, 50));
-		label.setBackground(Palette.GOLD);
-		label.setOpaque(true);
-		label.setBorder(BorderFactory.createRaisedBevelBorder());
-		label.setHorizontalAlignment(SwingConstants.CENTER);
 	}
 
 	@Override
 	public JComponent getComponent() {
+		if (label == null) {
+			label = new GDLabel();
+			label.setText(getName());
+			label.setPreferredSize(new Dimension(50, 50));
+			label.setBackground(Palette.GOLD);
+			label.setOpaque(true);
+			label.setBorder(BorderFactory.createRaisedBevelBorder());
+			label.setHorizontalAlignment(SwingConstants.CENTER);
+		}
 		return label;
 	}
 

Ghidra/Framework/Graph/src/test/java/ghidra/graph/graphs/TestVertex.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -22,7 +22,7 @@ import javax.swing.JComponent;
  */
 public class TestVertex extends AbstractTestVertex {
 
-	protected TestVertex(String name) {
+	public TestVertex(String name) {
 		super(name);
 	}
 

Ghidra/Framework/Graph/src/test/java/ghidra/graph/support/TestLayoutProvider.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -22,9 +22,10 @@ import javax.swing.Icon;
 
 import edu.uci.ics.jung.algorithms.layout.DAGLayout;
 import edu.uci.ics.jung.algorithms.layout.Layout;
-import ghidra.graph.graphs.TestEdge;
 import ghidra.graph.graphs.AbstractTestVertex;
+import ghidra.graph.graphs.TestEdge;
 import ghidra.graph.viewer.layout.LayoutProvider;
+import ghidra.graph.viewer.layout.VisualGraphLayout;
 import ghidra.graph.viewer.renderer.ArticulatedEdgeRenderer;
 import ghidra.graph.viewer.shape.ArticulatedEdgeTransformer;
 import ghidra.util.exception.CancelledException;
@@ -33,7 +34,8 @@ import ghidra.util.task.TaskMonitor;
 /**
  * A layout provider used for testing.
  */
-public class TestLayoutProvider implements LayoutProvider<AbstractTestVertex, TestEdge, TestVisualGraph> {
+public class TestLayoutProvider
+		implements LayoutProvider<AbstractTestVertex, TestEdge, TestVisualGraph> {
 
 	private ArticulatedEdgeTransformer<AbstractTestVertex, TestEdge> edgeShapeTransformer =
 		new ArticulatedEdgeTransformer<>();
@@ -41,7 +43,8 @@ public class TestLayoutProvider implements LayoutProvider<AbstractTestVertex, Te
 		new ArticulatedEdgeRenderer<>();
 
 	@Override
-	public TestGraphLayout getLayout(TestVisualGraph g, TaskMonitor monitor)
+	public VisualGraphLayout<AbstractTestVertex, TestEdge> getLayout(TestVisualGraph g,
+			TaskMonitor monitor)
 			throws CancelledException {
 		Layout<AbstractTestVertex, TestEdge> jungLayout = new DAGLayout<>(g);
 
@@ -54,11 +57,6 @@ public class TestLayoutProvider implements LayoutProvider<AbstractTestVertex, Te
 		return new TestGraphLayout(jungLayout);
 	}
 
-	// template method to allow tests to override the Jung layout in use
-	protected Layout<AbstractTestVertex, TestEdge> createJungLayout(TestVisualGraph g) {
-		return new DAGLayout<>(g);
-	}
-
 	@Override
 	public String getLayoutName() {
 		return "Test Layout";

Ghidra/Framework/Graph/src/test/java/ghidra/graph/support/TestVisualGraph.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -18,20 +18,21 @@ package ghidra.graph.support;
 import java.util.Collection;
 
 import ghidra.graph.graphs.*;
+import ghidra.graph.viewer.layout.VisualGraphLayout;
 
 /**
  * A visual graph implementation used for testing.
  */
 public class TestVisualGraph extends DefaultVisualGraph<AbstractTestVertex, TestEdge> {
 
-	private TestGraphLayout layout;
+	private VisualGraphLayout<AbstractTestVertex, TestEdge> layout;
 
 	@Override
-	public TestGraphLayout getLayout() {
+	public VisualGraphLayout<AbstractTestVertex, TestEdge> getLayout() {
 		return layout;
 	}
 
-	public void setLayout(TestGraphLayout layout) {
+	public void setLayout(VisualGraphLayout<AbstractTestVertex, TestEdge> layout) {
 		this.layout = layout;
 	}
 

Ghidra/Framework/Graph/src/test/java/ghidra/graph/viewer/layout/GridLocationMapTest.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -15,8 +15,7 @@
  */
 package ghidra.graph.viewer.layout;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 import java.util.List;
 
@@ -244,6 +243,56 @@ public class GridLocationMapTest {
 		assertCoordinates(v7, 2, 3);
 	}
 
+	@Test
+	public void testGetVertexColumnRanges() {
+		V v1 = new V("v1");
+		V v2 = new V("v2");
+		V v3 = new V("v3");
+		locations.set(v1, 0, 0);
+		locations.set(v2, 2, 4);
+		locations.set(v3, 2, 6);
+
+		GridRange[] columnRanges = locations.getVertexColumnRanges();
+		assertEquals(3, columnRanges.length);
+		assertEquals(new GridRange(0, 0), columnRanges[0]);
+		assertEquals(new GridRange(), columnRanges[1]);
+		assertEquals(new GridRange(4, 6), columnRanges[2]);
+
+	}
+
+	@Test
+	public void testAddGrids() {
+		// This method creates two grids with points and edge articulations. It then merges
+		// the other map into the first map with a given row and column shift. It then checks
+		// the merged grid has all the edge points and vertex points in the expected locations.
+		V v1 = new V("v1");
+		V v2 = new V("v2");
+		E e1 = new E(v1, v2);
+
+		V v3 = new V("v3");
+		V v4 = new V("v4");
+		E e2 = new E(v3, v4);
+
+		locations.set(v1, 0, 0);
+		locations.set(v2, 2, 4);
+		locations.setArticulations(e1, List.of(new GridPoint(3, 3)));
+
+		GridLocationMap<V, E> otherMap = new GridLocationMap<>();
+		otherMap.set(v3, 1, 1);
+		otherMap.set(v4, 2, 2);
+		otherMap.setArticulations(e1, List.of(new GridPoint(1, 2)));
+
+		locations.add(otherMap, 10, 10);
+
+		assertEquals(13, locations.width());
+		assertEquals(13, locations.height());
+
+		assertCoordinates(v1, 0, 0);
+		assertCoordinates(v2, 2, 4);
+		assertCoordinates(v3, 11, 11);
+		assertCoordinates(v4, 12, 12);
+
+	}
 //==================================================================================================
 // Private Methods
 //==================================================================================================	
@@ -253,7 +302,7 @@ public class GridLocationMapTest {
 		List<Row<V>> rows = locations.rows();
 		Row<V> row = getRow(rows, rowIndex);
 		assertEquals("Row " + rowIndex + " has wrong column count", size,
-			(int) row.getColumnCount());
+			row.getColumnCount());
 		assertEquals(startColumnIndex, (int) row.getStartColumn());
 	}
 
@@ -279,8 +328,8 @@ public class GridLocationMapTest {
 	}
 
 	private void assertCoordinates(V v, int row, int col) {
-		assertEquals("Row not set for '" + v + "'", row, (int) locations.row(v));
-		assertEquals("Column not set for '" + v + "'", col, (int) locations.col(v));
+		assertEquals("Row not set for '" + v + "'", row, locations.row(v));
+		assertEquals("Column not set for '" + v + "'", col, locations.col(v));
 	}
 
 	private class V extends TestVertex {