79 lines
1.8 KiB
JavaScript
79 lines
1.8 KiB
JavaScript
/*
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* Pixastic Lib - Brightness/Contrast filter - v0.1.1
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* Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
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* License: [http://www.pixastic.com/lib/license.txt]
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*/
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Pixastic.Actions.brightness = {
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process : function(params) {
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var brightness = parseInt(params.options.brightness,10) || 0;
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var contrast = parseFloat(params.options.contrast)||0;
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var legacy = !!(params.options.legacy && params.options.legacy != "false");
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if (legacy) {
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brightness = Math.min(150,Math.max(-150,brightness));
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} else {
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var brightMul = 1 + Math.min(150,Math.max(-150,brightness)) / 150;
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}
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contrast = Math.max(0,contrast+1);
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if (Pixastic.Client.hasCanvasImageData()) {
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var data = Pixastic.prepareData(params);
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var rect = params.options.rect;
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var w = rect.width;
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var h = rect.height;
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var p = w*h;
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var pix = p*4, pix1, pix2;
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var mul, add;
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if (contrast != 1) {
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if (legacy) {
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mul = contrast;
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add = (brightness - 128) * contrast + 128;
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} else {
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mul = brightMul * contrast;
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add = - contrast * 128 + 128;
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}
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} else { // this if-then is not necessary anymore, is it?
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if (legacy) {
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mul = 1;
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add = brightness;
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} else {
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mul = brightMul;
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add = 0;
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}
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}
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var r, g, b;
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while (p--) {
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if ((r = data[pix-=4] * mul + add) > 255 )
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data[pix] = 255;
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else if (r < 0)
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data[pix] = 0;
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else
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data[pix] = r;
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if ((g = data[pix1=pix+1] * mul + add) > 255 )
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data[pix1] = 255;
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else if (g < 0)
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data[pix1] = 0;
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else
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data[pix1] = g;
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if ((b = data[pix2=pix+2] * mul + add) > 255 )
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data[pix2] = 255;
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else if (b < 0)
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data[pix2] = 0;
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else
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data[pix2] = b;
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}
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return true;
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}
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},
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checkSupport : function() {
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return Pixastic.Client.hasCanvasImageData();
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}
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}
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