/*
 * Pixastic Lib - Glow - v0.1.0
 * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
 * MIT License [http://www.opensource.org/licenses/mit-license.php]
 */


Pixastic.Actions.glow = {
	process : function(params) {

		var amount = (parseFloat(params.options.amount)||0);
		var blurAmount = parseFloat(params.options.radius)||0;

		amount = Math.min(1,Math.max(0,amount));
		blurAmount = Math.min(5,Math.max(0,blurAmount));

		if (Pixastic.Client.hasCanvasImageData()) {
			var rect = params.options.rect;

			var blurCanvas = document.createElement("canvas");
			blurCanvas.width = params.width;
			blurCanvas.height = params.height;
			var blurCtx = blurCanvas.getContext("2d");
			blurCtx.drawImage(params.canvas,0,0);

			var scale = 2;
			var smallWidth = Math.round(params.width / scale);
			var smallHeight = Math.round(params.height / scale);

			var copy = document.createElement("canvas");
			copy.width = smallWidth;
			copy.height = smallHeight;

			var clear = true;
			var steps = Math.round(blurAmount * 20);

			var copyCtx = copy.getContext("2d");
			for (var i=0;i<steps;i++) {
				var scaledWidth = Math.max(1,Math.round(smallWidth - i));
				var scaledHeight = Math.max(1,Math.round(smallHeight - i));
	
				copyCtx.clearRect(0,0,smallWidth,smallHeight);
	
				copyCtx.drawImage(
					blurCanvas,
					0,0,params.width,params.height,
					0,0,scaledWidth,scaledHeight
				);
	
				blurCtx.clearRect(0,0,params.width,params.height);
	
				blurCtx.drawImage(
					copy,
					0,0,scaledWidth,scaledHeight,
					0,0,params.width,params.height
				);
			}

			var data = Pixastic.prepareData(params);
			var blurData = Pixastic.prepareData({canvas:blurCanvas,options:params.options});
			var w = rect.width;
			var h = rect.height;
			var w4 = w*4;
			var y = h;
			do {
				var offsetY = (y-1)*w4;
				var x = w;
				do {
					var offset = offsetY + (x*4-4);

					var r = data[offset] + amount * blurData[offset];
					var g = data[offset+1] + amount * blurData[offset+1];
					var b = data[offset+2] + amount * blurData[offset+2];
	
					if (r > 255) r = 255;
					if (g > 255) g = 255;
					if (b > 255) b = 255;
					if (r < 0) r = 0;
					if (g < 0) g = 0;
					if (b < 0) b = 0;

					data[offset] = r;
					data[offset+1] = g;
					data[offset+2] = b;

				} while (--x);
			} while (--y);

			return true;
		}
	},
	checkSupport : function() {
		return Pixastic.Client.hasCanvasImageData();
	}
}