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

   1 /*
   2  * Pixastic Lib - Posterize effect - 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.posterize = {
   8
   9         process : function(params) {
  10
  11
  12                 var numLevels = 256;
  13                 if (typeof params.options.levels != "undefined")
  14                         numLevels = parseInt(params.options.levels,10)||1;
  15
  16                 if (Pixastic.Client.hasCanvasImageData()) {
  17                         var data = Pixastic.prepareData(params);
  18
  19                         numLevels = Math.max(2,Math.min(256,numLevels));
  20
  21                         var numAreas = 256 / numLevels;
  22                         var numValues = 256 / (numLevels-1);
  23
  24                         var rect = params.options.rect;
  25                         var w = rect.width;
  26                         var h = rect.height;
  27                         var w4 = w*4;
  28                         var y = h;
  29                         do {
  30                                 var offsetY = (y-1)*w4;
  31                                 var x = w;
  32                                 do {
  33                                         var offset = offsetY + (x-1)*4;
  34
  35                                         var r = numValues * ((data[offset] / numAreas)>>0);
  36                                         var g = numValues * ((data[offset+1] / numAreas)>>0);
  37                                         var b = numValues * ((data[offset+2] / numAreas)>>0);
  38
  39                                         if (r > 255) r = 255;
  40                                         if (g > 255) g = 255;
  41                                         if (b > 255) b = 255;
  42
  43                                         data[offset] = r;
  44                                         data[offset+1] = g;
  45                                         data[offset+2] = b;
  46
  47                                 } while (--x);
  48                         } while (--y);
  49                         return true;
  50                 }
  51         },
  52         checkSupport : function() {
  53                 return Pixastic.Client.hasCanvasImageData();
  54         }
  55 }
  56
  57