/*
   * Pixastic Lib - Sharpen filter - v0.1.0
   * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
   * MIT License [http://www.opensource.org/licenses/mit-license.php]
   */
  
  Pixastic.Actions.sharpen = {
          process : function(params) {
  
                  var strength = 0;
                  if (typeof params.options.amount != "undefined")
                          strength = parseFloat(params.options.amount)||0;
  
                  if (strength < 0) strength = 0;
                  if (strength > 1) strength = 1;
  
                  if (Pixastic.Client.hasCanvasImageData()) {
                          var data = Pixastic.prepareData(params);
                          var dataCopy = Pixastic.prepareData(params, true)
  
                          var mul = 15;
                          var mulOther = 1 + 3*strength;
  
                          var kernel = [
                                  [0,         -mulOther,         0],
                                  [-mulOther,         mul,         -mulOther],
                                  [0,         -mulOther,         0]
                          ];
  
                          var weight = 0;
                          for (var i=0;i<3;i++) {
                                  for (var j=0;j<3;j++) {
                                          weight += kernel[i][j];
                                  }
                          }
  
                          weight = 1 / weight;
  
                          var rect = params.options.rect;
                          var w = rect.width;
                          var h = rect.height;
  
                          mul *= weight;
                          mulOther *= weight;
  
                          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*w4;
                                  var offsetYNext = nextY*w4;
  
                                  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]
                                                  - dataCopy[offset-4]
                                                  - dataCopy[offset+4]
                                                  - dataCopy[offsetNext])                * mulOther
                                                  + dataCopy[offset]         * mul
                                                  );
  
                                          var g = ((
                                                  - dataCopy[offsetPrev+1]
                                                  - dataCopy[offset-3]
                                                  - dataCopy[offset+5]
                                                  - dataCopy[offsetNext+1])        * mulOther
                                                  + dataCopy[offset+1]         * mul
                                                  );
  
                                          var b = ((
                                                  - dataCopy[offsetPrev+2]
                                                  - dataCopy[offset-2]
                                                  - dataCopy[offset+6]
                                                  - dataCopy[offsetNext+2])        * mulOther
                                                  + dataCopy[offset+2]         * mul
                                                  );
  
                                          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();
          }
  }