Optimize unnecessarily

and simplify returning an Array

src/helpers.js

@@ -41,25 +41,23 @@ function E(t){
 	return document.createElement(t);
 }
 
-// TODO optimization: could keep one canvas for this purpose
-function get_rgba_from_color(color){
-	
-	var _c = new Canvas(1, 1);
-	
-	_c.ctx.fillStyle = color;
-	_c.ctx.fillRect(0, 0, 1, 1);
-	
-	var _id = _c.ctx.getImageData(0, 0, 1, 1);
-	
-	// We could just return _id.data, but let's return an array instead
-	// Could also do Array.from(_id.data)
-	var fill_r = _id.data[0];
-	var fill_g = _id.data[1];
-	var fill_b = _id.data[2];
-	var fill_a = _id.data[3];
-	return [fill_r, fill_g, fill_b, fill_a];
-	
-}
+var get_rgba_from_color = (function(){
+	var _single_pixel_canvas = new Canvas(1, 1);
+
+	function get_rgba_from_color(color){
+		
+		_single_pixel_canvas.ctx.fillStyle = color;
+		_single_pixel_canvas.ctx.fillRect(0, 0, 1, 1);
+		
+		var _id = _single_pixel_canvas.ctx.getImageData(0, 0, 1, 1);
+		
+		// We could just return _id.data, but let's return an Array instead
+		// I'm not totally sure _id.data wouldn't keep _id around in memory
+		return Array.from(_id.data);
+	}
+
+	return get_rgba_from_color;
+}());
 
 function Canvas(width, height){
 	var image = width;

src/image-manipulation.js

@@ -211,6 +211,15 @@ function brosandham_line(x1, y1, x2, y2, callback){
 
 function draw_fill(ctx, x, y, fill_r, fill_g, fill_b, fill_a){
 	
+	// TODO: split up processing in case it takes too long?
+	// progress bar and abort button (outside of image-manipulation.js)
+	// or at least just free up the main thread every once in a while
+	// TODO: speed up with typed arrays? https://hacks.mozilla.org/2011/12/faster-canvas-pixel-manipulation-with-typed-arrays/
+	// could avoid endianness issues if only copying colors
+	// the jsperf only shows ~15% improvement
+	// maybe do something fancier like special-casing large chunks of single-color image
+	// (octree? or just have a higher level stack of chunks to fill and check at if a chunk is homogeneous)
+
 	var stack = [[x, y]];
 	var c_width = canvas.width;
 	var c_height = canvas.height;