/*
   * Pixastic Lib - Edge detection filter - v0.1.1
   * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
   * MIT License [http://www.opensource.org/licenses/mit-license.php]
   */
  
  Pixastic.Actions.edges = {
          process : function(params) {
  
                  var mono = !!(params.options.mono);
  
                  var strength = 1.0;
  
                  //if (typeof params.options.strength != "undefined")
                  //        strength = parseFloat(params.options.strength)||0;
  
                  var invert = !!(params.options.invert);
  
                  if (Pixastic.Client.hasCanvasImageData()) {
                          var data = Pixastic.prepareData(params);
                          var dataCopy = Pixastic.prepareData(params, true)
  
                          var c = -strength/8;
                          var kernel = [
                                  [c,         c,         c],
                                  [c,         1,         c],
                                  [c,         c,         c]
                          ];
  
                          weight = 1/c;
  
                          var rect = params.options.rect;
                          var w = rect.width;
                          var h = rect.height;
  
                          var w4 = w*4;
                          var y = h;
                          do {
                                  var offsetY = (y-1)*w4;
  
                                  var nextY = (y == h) ? y - 1 : y;
                                  var prevY = (y == 1) ? 0 : y-2;
  
                                  var offsetYPrev = prevY*w*4;
                                  var offsetYNext = nextY*w*4;
  
                                  var x = w;
                                  do {
                                          var offset = offsetY + (x*4-4);
  
                                          var offsetPrev = offsetYPrev + ((x == 1) ? 0 : x-2) * 4;
                                          var offsetNext = offsetYNext + ((x == w) ? x-1 : x) * 4;
          
                                          var r = ((dataCopy[offsetPrev-4]
                                                  + dataCopy[offsetPrev]
                                                  + dataCopy[offsetPrev+4]
                                                  + dataCopy[offset-4]
                                                  + dataCopy[offset+4]
                                                  + dataCopy[offsetNext-4]
                                                  + dataCopy[offsetNext]
                                                  + dataCopy[offsetNext+4]) * c
                                                  + dataCopy[offset]
                                                  ) 
  						* weight;
          
                                          var g = ((dataCopy[offsetPrev-3]
                                                  + dataCopy[offsetPrev+1]
                                                  + dataCopy[offsetPrev+5]
                                                  + dataCopy[offset-3]
                                                  + dataCopy[offset+5]
                                                  + dataCopy[offsetNext-3]
                                                  + dataCopy[offsetNext+1]
                                                  + dataCopy[offsetNext+5]) * c
                                                  + dataCopy[offset+1])
  						* weight;
          
                                          var b = ((dataCopy[offsetPrev-2]
                                                  + dataCopy[offsetPrev+2]
                                                  + dataCopy[offsetPrev+6]
                                                  + dataCopy[offset-2]
                                                  + dataCopy[offset+6]
                                                  + dataCopy[offsetNext-2]
                                                  + dataCopy[offsetNext+2]
                                                  + dataCopy[offsetNext+6]) * c
                                                  + dataCopy[offset+2])
  						* weight;
  
                                          if (mono) {
                                                  var brightness = (r*0.3 + g*0.59 + b*0.11)||0;
                                                  if (invert) brightness = 255 - brightness;
                                                  if (brightness < 0 ) brightness = 0;
                                                  if (brightness > 255 ) brightness = 255;
                                                  r = g = b = brightness;
                                          } else {
                                                  if (invert) {
                                                          r = 255 - r;
                                                          g = 255 - g;
                                                          b = 255 - b;
                                                  }
                                                  if (r < 0 ) r = 0;
                                                  if (g < 0 ) g = 0;
                                                  if (b < 0 ) b = 0;
                                                  if (r > 255 ) r = 255;
                                                  if (g > 255 ) g = 255;
                                                  if (b > 255 ) b = 255;
                                          }
  
                                          data[offset] = r;
                                          data[offset+1] = g;
                                          data[offset+2] = b;
  
                                  } while (--x);
                          } while (--y);
  
                          return true;
                  }
          },
          checkSupport : function() {
                  return Pixastic.Client.hasCanvasImageData();
          }
  }