topical media & game development
graphic-canvas-util-pixastic-actions-unsharpmask.js / js
/*
* Pixastic Lib - USM - 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.unsharpmask = {
process : function(params) {
var amount = (parseFloat(params.options.amount)||0);
var blurAmount = parseFloat(params.options.radius)||0;
var threshold = parseFloat(params.options.threshold)||0;
amount = Math.min(500,Math.max(0,amount)) / 2;
blurAmount = Math.min(5,Math.max(0,blurAmount)) / 10;
threshold = Math.min(255,Math.max(0,threshold));
threshold--;
var thresholdNeg = -threshold;
amount *= 0.016;
amount++;
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 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 difR = data[offset] - blurData[offset];
if (difR > threshold || difR < thresholdNeg) {
var blurR = blurData[offset];
blurR = amount * difR + blurR;
data[offset] = blurR > 255 ? 255 : (blurR < 0 ? 0 : blurR);
}
var difG = data[offset+1] - blurData[offset+1];
if (difG > threshold || difG < thresholdNeg) {
var blurG = blurData[offset+1];
blurG = amount * difG + blurG;
data[offset+1] = blurG > 255 ? 255 : (blurG < 0 ? 0 : blurG);
}
var difB = data[offset+2] - blurData[offset+2];
if (difB > threshold || difB < thresholdNeg) {
var blurB = blurData[offset+2];
blurB = amount * difB + blurB;
data[offset+2] = blurB > 255 ? 255 : (blurB < 0 ? 0 : blurB);
}
} while (--x);
} while (--y);
return true;
}
},
checkSupport : function() {
return Pixastic.Client.hasCanvasImageData();
}
}
(C) Æliens
20/2/2008
You may not copy or print any of this material without explicit permission of the author or the publisher.
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