Added Asynchronous Web Worker support (animWorker.js), modified GIFEn…

…coder.js to support animWorker and added anim.js: example code to show how to use animWorker.

GIFEncoder.js

@@ -298,6 +298,18 @@
 
 		}
 
+		var cont = exports.cont = function cont()/*Boolean*/
+		{
+
+		    reset(); 
+		    var ok/*Boolean*/ = true;
+		    closeStream = false;
+		    out = new ByteArray;
+
+		    return started = ok;
+
+		}
+
 		/**
 		* Analyzes image colors and creates color map.
 		*/
@@ -534,6 +546,7 @@
 		var setProperties = exports.setProperties = function setProperties(has_start, is_first){
 		  started = has_start;
 		  firstFrame = is_first;
+		  //out = new ByteArray; //??
 		}
 
 		return exports

anim.js

@@ -0,0 +1,107 @@
+//This Demonstrates calling the animWorker.js web worker, allowing for non-blocking
+//Gif building.
+
+
+function animDelayValue() //Gets a user defined frame delay from user input (dom element), displays current value on dom
+{
+	var value = new Number(document.getElementById("animDelay").value/1000);
+	value.toFixed(2);
+	document.getElementById("animDelayVal").innerHTML = value;
+}
+animDelayValue(); //initialize delay value display 
+this.animDelayValue = animDelayValue;	//make animDelayValue global
+this.gifalizer = function() //function, called from DOM to build gif.
+{
+	function getAnimScaleFactor()
+	{
+		var autosaveElements = document.getElementsByName("animScale"); //DOM widget to set scale factor to 100%, 50% or 25%
+		var autosaveValue = "4"
+		for (var i=0; i < autosaveElements.length; i++)
+		{
+			if (autosaveElements[i].checked)
+			{
+				autosaveValue = autosaveElements[i].value;
+				break;
+			}
+		}
+		if(autosaveValue == "1")
+		{
+			return 1;
+		}
+		if(autosaveValue == "2")
+		{
+			return 2;
+		}
+		else
+		{
+			return 4;
+		}
+	}
+
+	var delay = document.getElementById("animDelay").value;
+	var scale = getAnimScaleFactor();
+
+	var animation_parts = new Array(paintedCanvases.length);
+
+	var worker = new Worker('animWorker.js');
+	//worker.onmessage = function(e)
+	//{
+	//	console.log(e.data);
+	//}
+
+	//call web worker. 
+	worker.onmessage = function(e)
+	{
+		//handle stuff, like get the frame_index
+		var frame_index = e.data["frame_index"];
+		var frame_data = e.data["frame_data"];
+		animation_parts[frame_index] = frame_data;
+		console.log(frame_index);
+		for(var j = 0; j < paintedCanvases.length; j++)
+		{
+			if(animation_parts[j] == null)
+			{
+				return;
+			}
+		}
+		console.log("append");
+		//check when everything else is done and then do animation_parts.join('') and have fun
+		var binary_gif = animation_parts.join('');
+		var data_url = 'data:image/gif;base64,'+window.btoa(binary_gif);
+
+		var gifItem = new Image();
+		gifItem.src = data_url;
+		var thumbs = document.getElementById("gifContainer");
+
+		//nuke all child nodes!
+		while(thumbs.hasChildNodes())
+		{
+			thumbs.removeChild(thumbs.lastChild);
+		}
+		document.getElementById("gifContainer").appendChild(gifItem);	
+	}
+
+	var imageItems = new Array(); //hacky way to ensure that an arbitrary number of onload events occur.
+	//paintedCanvases is an array of canvas data generated by a canvas toDataURL calls elsewhere in the parent scope. Replicate this how you wish.
+	for(var i = 0; i < paintedCanvases.length; i++)
+	{
+		imageItems[i] = new Image();
+		imageItems[i].src = paintedCanvases[i];
+		imageItems[i].isloaded = false;
+		imageItems[i].index = i;
+		imageItems[i].onload = function()
+		{
+			var scratchCanvas = document.createElement("canvas"); 
+			scratchCanvas.width = comicPane.width/scale;
+			scratchCanvas.height = comicPane.height/scale;
+			var scratchCanvasContext = scratchCanvas.getContext("2d");
+			scratchCanvasContext.fillStyle = "#FFFFFF";
+			scratchCanvasContext.fillRect(0,0,scratchCanvas.width, scratchCanvas.height);
+			scratchCanvasContext.drawImage(this,0,0,scratchCanvas.width,scratchCanvas.height);
+			var imdata = scratchCanvasContext.getImageData(0,0, scratchCanvas.width, scratchCanvas.height).data;
+			console.log(this.index);
+			worker.postMessage({"frame_index": this.index, "delay": delay, "frame_length":paintedCanvases.length-1, "height":scratchCanvas.height, "width":scratchCanvas.width, "imageData":imdata}); //imarray.join(',')
+
+		}
+	}
+}

animWorker.js

@@ -0,0 +1,47 @@
+importScripts('LZWEncoder.js', 'NeuQuant.js', 'GIFEncoder.js');      /* imports three scripts */
+
+self.onmessage = function(event) {
+  //console.log("message!");
+  //alert("message");
+  //self.postMessage(event.data);
+  //return;
+  var frame_index,
+    frame_length,
+    height, 
+    width,
+    delay,
+    imageData; //get it from onmessage
+
+  frame_index = event.data["frame_index"];
+  frame_length = event.data["frame_length"];
+  height = event.data["height"];
+  width = event.data["width"];
+  imageData = event.data["imageData"];
+  delay = event.data["delay"];
+
+  var encoder = new GIFEncoder(); //create a new GIFEncoder for every new job
+  encoder.setRepeat(0); 	//0  -> loop forever
+  //1+ -> loop n times then stop
+  encoder.setQuality(1);
+  encoder.setSize(width, height); 
+  encoder.setDelay(delay);	//go to next frame every n milliseconds
+
+  if(frame_index == 0)
+  {
+
+    encoder.start();
+  }
+  else
+  {
+    //alert();
+    encoder.cont();
+    encoder.setProperties(true, false); //started, firstFrame
+  }
+
+  encoder.addFrame(imageData, true);
+  if(frame_length == frame_index)
+  {
+    encoder.finish();
+  }
+  self.postMessage({"frame_index":frame_index, "frame_data":encoder.stream().getData()}) //on the page, search for the GIF89a to see the frame_index
+};