/*
 * Pixastic Lib - Sharpen filter - 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.sharpen = {
	process : function(params) {

		var strength = 0;
		if (typeof params.options.amount != "undefined")
			strength = parseFloat(params.options.amount)||0;

		if (strength < 0) strength = 0;
		if (strength > 1) strength = 1;

		if (Pixastic.Client.hasCanvasImageData()) {
			var data = Pixastic.prepareData(params);
			var dataCopy = Pixastic.prepareData(params, true)

			var mul = 15;
			var mulOther = 1 + 3*strength;

			var kernel = [
				[0, 	-mulOther, 	0],
				[-mulOther, 	mul, 	-mulOther],
				[0, 	-mulOther, 	0]
			];

			var weight = 0;
			for (var i=0;i<3;i++) {
				for (var j=0;j<3;j++) {
					weight += kernel[i][j];
				}
			}

			weight = 1 / weight;

			var rect = params.options.rect;
			var w = rect.width;
			var h = rect.height;

			mul *= weight;
			mulOther *= weight;

			var w4 = w*4;
			var y = h;
			do {
				var offsetY = (y-1)*w4;

				var nextY = (y == h) ? y - 1 : y;
				var prevY = (y == 1) ? 0 : y-2;

				var offsetYPrev = prevY*w4;
				var offsetYNext = nextY*w4;

				var x = w;
				do {
					var offset = offsetY + (x*4-4);

					var offsetPrev = offsetYPrev + ((x == 1) ? 0 : x-2) * 4;
					var offsetNext = offsetYNext + ((x == w) ? x-1 : x) * 4;

					var r = ((
						- dataCopy[offsetPrev]
						- dataCopy[offset-4]
						- dataCopy[offset+4]
						- dataCopy[offsetNext])		* mulOther
						+ dataCopy[offset] 	* mul
						);

					var g = ((
						- dataCopy[offsetPrev+1]
						- dataCopy[offset-3]
						- dataCopy[offset+5]
						- dataCopy[offsetNext+1])	* mulOther
						+ dataCopy[offset+1] 	* mul
						);

					var b = ((
						- dataCopy[offsetPrev+2]
						- dataCopy[offset-2]
						- dataCopy[offset+6]
						- dataCopy[offsetNext+2])	* mulOther
						+ dataCopy[offset+2] 	* mul
						);


					if (r < 0 ) r = 0;
					if (g < 0 ) g = 0;
					if (b < 0 ) b = 0;
					if (r > 255 ) r = 255;
					if (g > 255 ) g = 255;
					if (b > 255 ) b = 255;

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

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

			return true;

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