76 lines
2 KiB
JavaScript
Executable file
76 lines
2 KiB
JavaScript
Executable file
/*
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* Pixastic Lib - Histogram - v0.1.0
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* Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
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* MIT License [http://www.opensource.org/licenses/mit-license.php]
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*/
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Pixastic.Actions.histogram = {
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process : function(params) {
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var average = !!(params.options.average);
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var paint = !!(params.options.paint);
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var color = params.options.color || "rgba(255,255,255,0.5)";
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var values = [];
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if (typeof params.options.returnValue != "object") {
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params.options.returnValue = {values:[]};
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}
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var returnValue = params.options.returnValue;
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if (typeof returnValue.values != "array") {
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returnValue.values = [];
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}
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values = returnValue.values;
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if (Pixastic.Client.hasCanvasImageData()) {
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var data = Pixastic.prepareData(params);
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params.useData = false;
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for (var i=0;i<256;i++) {
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values[i] = 0;
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}
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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 w4 = w*4;
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var y = h;
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do {
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var offsetY = (y-1)*w4;
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var x = w;
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do {
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var offset = offsetY + (x*4-4);
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var brightness = average ?
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Math.round((data[offset]+data[offset+1]+data[offset+2])/3)
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: Math.round(data[offset]*0.3 + data[offset+1]*0.59 + data[offset+2]*0.11);
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values[brightness]++;
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} while (--x);
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} while (--y);
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if (paint) {
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var maxValue = 0;
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for (var i=0;i<256;i++) {
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if (values[i] > maxValue) {
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maxValue = values[i];
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}
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}
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var heightScale = params.height / maxValue;
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var widthScale = params.width / 256;
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var ctx = params.canvas.getContext("2d");
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ctx.fillStyle = color;
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for (var i=0;i<256;i++) {
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ctx.fillRect(
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i * widthScale, params.height - heightScale * values[i],
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widthScale, values[i] * heightScale
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);
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}
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}
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returnValue.values = values;
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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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