feat(scrcpy): improve support for scroll and hover

libraries/scrcpy/src/control/hover-helper.ts

@@ -0,0 +1,51 @@
+import {
+    AndroidMotionEventAction,
+    type ScrcpyInjectTouchControlMessage,
+} from "./inject-touch.js";
+import { ScrcpyControlMessageType } from "./type.js";
+
+/**
+ * On Android, touching the screen with a finger will disable mouse cursor.
+ * However, Scrcpy doesn't do that, and can inject two pointers at the same time.
+ * This can cause finger events to be "ignored" because mouse is still the primary pointer.
+ *
+ * This helper class injects an extra `ACTION_UP` event,
+ * so Scrcpy server can remove the previously hovering pointer.
+ */
+export class ScrcpyHoverHelper {
+    // AFAIK, only mouse and pen can have hover state
+    // and you can't have two mouses or pens.
+    private lastHoverMessage: ScrcpyInjectTouchControlMessage | undefined;
+
+    public process(
+        message: Omit<ScrcpyInjectTouchControlMessage, "type">
+    ): ScrcpyInjectTouchControlMessage[] {
+        const result: ScrcpyInjectTouchControlMessage[] = [];
+
+        // A different pointer appeared,
+        // Cancel previously hovering pointer so Scrcpy server can free up the pointer ID.
+        if (
+            this.lastHoverMessage &&
+            this.lastHoverMessage.pointerId !== message.pointerId
+        ) {
+            // TODO: Inject MotionEvent.ACTION_HOVER_EXIT
+            // From testing, it seems no App cares about this event.
+            result.push({
+                ...this.lastHoverMessage,
+                action: AndroidMotionEventAction.Up,
+            });
+            this.lastHoverMessage = undefined;
+        }
+
+        if (message.action === AndroidMotionEventAction.HoverMove) {
+            // TODO: Inject MotionEvent.ACTION_HOVER_ENTER
+            this.lastHoverMessage = message as ScrcpyInjectTouchControlMessage;
+        }
+
+        (message as ScrcpyInjectTouchControlMessage).type =
+            ScrcpyControlMessageType.InjectTouch;
+        result.push(message as ScrcpyInjectTouchControlMessage);
+
+        return result;
+    }
+}