js2/mwEmbed/libClipEdit/pixastic-lib/actions/histogram.js

   1 /*
   2  * Pixastic Lib - Histogram - v0.1.0
   3  * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
   4  * MIT License [http://www.opensource.org/licenses/mit-license.php]
   5  */
   6
   7 Pixastic.Actions.histogram = {
   8         process : function(params) {
   9
  10                 var average = !!(params.options.average);
  11                 var paint = !!(params.options.paint);
  12                 var color = params.options.color || "rgba(255,255,255,0.5)";
  13                 var values = [];
  14                 if (typeof params.options.returnValue != "object") {
  15                         params.options.returnValue = {values:[]};
  16                 }
  17                 var returnValue = params.options.returnValue;
  18                 if (typeof returnValue.values != "array") {
  19                         returnValue.values = [];
  20                 }
  21                 values = returnValue.values;
  22
  23                 if (Pixastic.Client.hasCanvasImageData()) {
  24                         var data = Pixastic.prepareData(params);
  25                         params.useData = false;
  26
  27                         for (var i=0;i<256;i++) {
  28                                 values[i] = 0;
  29                         }
  30
  31                         var rect = params.options.rect;
  32                         var w = rect.width;
  33                         var h = rect.height;
  34                         var w4 = w*4;
  35                         var y = h;
  36                         do {
  37                                 var offsetY = (y-1)*w4;
  38                                 var x = w;
  39                                 do {
  40                                         var offset = offsetY + (x*4-4);
  41                                         var brightness = average ?
  42                                                 Math.round((data[offset]+data[offset+1]+data[offset+2])/3)
  43                                                 : Math.round(data[offset]*0.3 + data[offset+1]*0.59 + data[offset+2]*0.11);
  44                                         values[brightness]++;
  45
  46                                 } while (--x);
  47                         } while (--y);
  48
  49                         if (paint) {
  50                                 var maxValue = 0;
  51                                 for (var i=0;i<256;i++) {
  52                                         if (values[i] > maxValue) {
  53                                                 maxValue = values[i];
  54                                         }
  55                                 }
  56                                 var heightScale = params.height / maxValue;
  57                                 var widthScale = params.width / 256;
  58                                 var ctx = params.canvas.getContext("2d");
  59                                 ctx.fillStyle = color;
  60                                 for (var i=0;i<256;i++) {
  61                                         ctx.fillRect(
  62                                                 i * widthScale, params.height - heightScale * values[i],
  63                                                 widthScale, values[i] * heightScale
  64                                         );
  65                                 }
  66                         }
  67
  68                         returnValue.values = values;
  69
  70                         return true;
  71                 }
  72         },
  73         checkSupport : function() {
  74                 return Pixastic.Client.hasCanvasImageData();
  75         }
  76 }