loads of changes, methods are now mostly assigned to the prototype (for better or worse), the constructer accepts an array of options, in fitWidth mode the comic will scale on window resize

scripts.js

@@ -1,5 +1,5 @@
 
-var book;
+var book
 
 window.onload = function() {
 
@@ -13,13 +13,30 @@ window.onload = function() {
 		"http://dev.justforcomics.com/get/image/?f=comics/extracted/oni_whiteout_melt_1/06.jpg"
 	];
 
-	book = new ComicBook();
-	book.draw("comic", pages);
+	var options = {
+		displayMode: "double",
+		zoomMode: "fitWidth"
+	}
+
+	book = new ComicBook("comic", pages, options);
+	book.draw();
 }
 
-function ComicBook() {
+window.onresize = function() {
+	book.draw();
+}
+
+function ComicBook(id, srcs, opts) {
+
+	this.id = id;
+	this.srcs = srcs;	
+
+	var defaults = {
+		displayMode: "double",	// single / double
+		zoomMode: "fitWidth"	// manual / fitWidth
+	}
+	var options = merge(defaults, opts);
 
-	var srcs = [];
 	var pages = [];
 	var canvas;
 	var context;
@@ -29,25 +46,24 @@ function ComicBook() {
 	var loaded = 0;
 	
 	var scale = 1;
-	var displayMode = "double" // single / double
-	var zoomMode = "fitWidth"; // manual / fitWidth
 
 	/* 
 	 * @param {String} id The canvas ID to draw the comic on.
 	 * @param {Object} srcs An array of all the comic page srcs, in order
 	 * @see #preload
 	 */
-	this.draw = function(id, srcs) {
+	ComicBook.prototype.draw = function() {
 	
 		// setup canvas
-		canvas = document.getElementById(id);
+		canvas = document.getElementById(this.id);
 		context = canvas.getContext("2d");
 
-		// preload images
-		preload(srcs);
-		
+		// preload images if needed
+		if (pages.length != this.srcs.length) this.preload(this.srcs);
+		else this.drawPage();
+
 		// add page controls
-		canvas.addEventListener("click", navigation, false);
+		canvas.addEventListener("click", ComicBook.prototype.navigation, false);
 	}
 
 	/*
@@ -55,10 +71,10 @@ function ComicBook() {
 	 * 
 	 * @param new_scale {Number} Scale the canvas to this ratio
 	 */
-	this.zoom = function(new_scale) {
-		zoomMode = "manual";
+	ComicBook.prototype.zoom = function(new_scale) {
+		options.zoomMode = "manual";
 		scale = new_scale;
-		drawPage();
+		this.drawPage();
 	}
 	
 	/**
@@ -67,7 +83,7 @@ function ComicBook() {
 	 * @param srcs {Object} srcs
 	 * @see #drawPage
 	 */
-	function preload(srcs) {
+	ComicBook.prototype.preload = function(srcs) {
 
 		if (srcs.length < buffer) buffer = srcs.length; // don't get stuck if the buffer level is higher than the number of pages
 
@@ -78,9 +94,8 @@ function ComicBook() {
 			page.src = src;
 			
 			page.onload = function() {
-				
-				pages[i] = this; loaded++;
-				if (loaded == buffer) drawPage();
+				pages[i] = this;loaded++;
+				if (loaded == buffer) ComicBook.prototype.drawPage();
 			}
 		});
 	}
@@ -91,34 +106,30 @@ function ComicBook() {
 	 * TODO: break this down into drawSinglePage() & drawDoublePage()
 	 * TODO: if the current browser doesn't have canvas support, use img tags
 	 */
-	function drawPage() {
-
+	ComicBook.prototype.drawPage = function() {
+	
 		var zoom_scale;
 		var page = pages[pointer];
 		var page2 = pages[pointer + 1];
-		
+
 		if (typeof page != "object") throw "invalid page";
 
 		var width = page.width;
-		var height = page.height;
 		
-		if (displayMode == "double") {
+		if (options.displayMode == "double") {
 
-			// for double page spreads, factor in the width of both pages, set the height to the tallest page
-			if (typeof page2 == "object") {
-				width += page2.width;
-				if (page2.height > page.height) height = page2.height;
-			}
+			// for double page spreads, factor in the width of both pages
+			if (typeof page2 == "object") width += page2.width;
 			
 			// if this is the last page and there is no page2, still keep the canvas wide
 			else width += width;
 		}
-		
+
 		// update the page scale if a non manual mode has been chosen
-		switch(zoomMode) {
+		switch(options.zoomMode) {
 
 			case "manual":
-				zoom_scale = (displayMode == "double") ? scale * 2 : scale;
+				zoom_scale = (options.displayMode == "double") ? scale * 2 : scale;
 				break;
 				
 			case "fitWidth":
@@ -127,22 +138,22 @@ function ComicBook() {
 					  : window.innerWidth / width; // scale down if the window is narrower than the page
 				break;
 				
-			default: throw "invalid zoomMode";
+			default:throw "invalid zoomMode";
 		}
 		
 		var canvas_width  = page.width * zoom_scale;
 		var canvas_height = page.height * zoom_scale;
 
-		var page_width = (zoomMode == "manual") ? page.width * scale : canvas_width;
-		var page_height = (zoomMode == "manual") ? page.height * scale : canvas_height;
+		var page_width = (options.zoomMode == "manual") ? page.width * scale : canvas_width;
+		var page_height = (options.zoomMode == "manual") ? page.height * scale : canvas_height;
 		
 		// make sure the canvas is always at least full screen, even if the page is more narrow than the screen
 		canvas.width = (canvas_width < window.innerWidth) ? window.innerWidth : canvas_width;
 		canvas.height = (canvas_height < window.innerHeight) ? window.innerHeight : canvas_height;
-
+		
 		// draw the page(s)
 		context.drawImage(page, 0, 0, page_width, page_height);
-		if (displayMode == "double" && typeof page2 == "object") context.drawImage(page2, page_width, 0, page_width, page_height);
+		if (options.displayMode == "double" && typeof page2 == "object") context.drawImage(page2, page_width, 0, page_width, page_height);
 		
 	}
 
@@ -151,10 +162,10 @@ function ComicBook() {
 	 * 
 	 * @see #drawPage
 	 */
-	function drawNextPage() {
+	ComicBook.prototype.drawNextPage = function() {
 		if (pointer + 1 < pages.length) {
 			pointer++;
-			drawPage();
+			this.drawPage();
 		}
 	}
 
@@ -163,21 +174,21 @@ function ComicBook() {
 	 *
 	 * @see #drawPage
 	 */
-	function drawPrevPage() {
+	ComicBook.prototype.drawPrevPage = function() {
 		if (pointer > 0) {
 			pointer--;
-			drawPage();
+			this.drawPage();
 		}
 	}
-
-	function navigation(e) {
+	
+	ComicBook.prototype.navigation = function(e) {
 
 		switch (e.type) {
 
 			case "click":
 				switch (getCursorPosition(e)) {
-					case "left": drawPrevPage(); break;
-					case "right": drawNextPage(); break;
+					case "left": ComicBook.prototype.drawPrevPage(); break;
+					case "right": ComicBook.prototype.drawNextPage(); break;
 				}
 				break;
 			
@@ -191,19 +202,38 @@ function ComicBook() {
 	 * Thanks to: Mark Pilgrim & http://diveintohtml5.org/canvas.html
 	 */
 	function getCursorPosition(e) {
-		
+	
 		var x;
 
 		// check if page relative positions exist
 		if (e.pageX) x = e.pageX;
-
+		
 		// if not figure them out
 		else  x = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
-
+		
 		// make the position relative to the canvas
 		x -= canvas.offsetLeft;
-
+		
 		// check if the user clicked on the left or right side
 		return (x <= canvas.width / 2) ? 'left' : 'right';
 	}
-}
+
+	/**
+	 * Merge two arrays. Any properties in b will replace the same properties in
+	 * a. New properties from b will be added to a.
+	 *
+	 * @param a {Object}
+	 * @param b {Object}
+	 */
+	function merge(a, b) {
+	
+		if (typeof b == "undefined") b = {};
+
+		for (prop in a) {
+			if (prop in b) continue;
+			b[prop] = a[prop];
+		}
+		
+		return b;
+	}
+}