/*
   * Pixastic Lib - Emboss 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.emboss = {
          process : function(params) {
  
                  var strength = parseFloat(params.options.strength)||1;
                  var greyLevel = typeof params.options.greyLevel != "undefined" ? parseInt(params.options.greyLevel) : 180;
                  var direction = params.options.direction||"topleft";
                  var blend = !!params.options.blend;
  
                  var dirY = 0;
                  var dirX = 0;
  
                  switch (direction) {
                          case "topleft":                        // top left
                                  dirY = -1;
                                  dirX = -1;
                                  break;
                          case "top":                        // top
                                  dirY = -1;
                                  dirX = 0;
                                  break;
                          case "topright":                        // top right
                                  dirY = -1;
                                  dirX = 1;
                                  break;
                          case "right":                        // right
                                  dirY = 0;
                                  dirX = 1;
                                  break;
                          case "bottomright":                        // bottom right
                                  dirY = 1;
                                  dirX = 1;
                                  break;
                          case "bottom":                        // bottom
                                  dirY = 1;
                                  dirX = 0;
                                  break;
                          case "bottomleft":                        // bottom left
                                  dirY = 1;
                                  dirX = -1;
                                  break;
                          case "left":                        // left
                                  dirY = 0;
                                  dirX = -1;
                                  break;
                  }
  
                  if (Pixastic.Client.hasCanvasImageData()) {
                          var data = Pixastic.prepareData(params);
                          var dataCopy = Pixastic.prepareData(params, true)
  
                          var invertAlpha = !!params.options.invertAlpha;
                          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 otherY = dirY;
                                  if (y + otherY < 1) otherY = 0;
                                  if (y + otherY > h) otherY = 0;
  
                                  var offsetYOther = (y-1+otherY)*w*4;
  
                                  var x = w;
                                  do {
                                                  var offset = offsetY + (x-1)*4;
  
                                                  var otherX = dirX;
                                                  if (x + otherX < 1) otherX = 0;
                                                  if (x + otherX > w) otherX = 0;
  
                                                  var offsetOther = offsetYOther + (x-1+otherX)*4;
  
                                                  var dR = dataCopy[offset] - dataCopy[offsetOther];
                                                  var dG = dataCopy[offset+1] - dataCopy[offsetOther+1];
                                                  var dB = dataCopy[offset+2] - dataCopy[offsetOther+2];
  
                                                  var dif = dR;
                                                  var absDif = dif > 0 ? dif : -dif;
  
                                                  var absG = dG > 0 ? dG : -dG;
                                                  var absB = dB > 0 ? dB : -dB;
  
                                                  if (absG > absDif) {
                                                          dif = dG;
                                                  }
                                                  if (absB > absDif) {
                                                          dif = dB;
                                                  }
  
                                                  dif *= strength;
  
                                                  if (blend) {
                                                          var r = data[offset] + dif;
                                                          var g = data[offset+1] + dif;
                                                          var b = data[offset+2] + dif;
  
                                                          data[offset] = (r > 255) ? 255 : (r < 0 ? 0 : r);
                                                          data[offset+1] = (g > 255) ? 255 : (g < 0 ? 0 : g);
                                                          data[offset+2] = (b > 255) ? 255 : (b < 0 ? 0 : b);
                                                  } else {
                                                          var grey = greyLevel - dif;
                                                          if (grey < 0) {
                                                                  grey = 0;
                                                          } else if (grey > 255) {
                                                                  grey = 255;
                                                          }
  
                                                          data[offset] = data[offset+1] = data[offset+2] = grey;
                                                  }
  
                                  } while (--x);
                          } while (--y);
                          return true;
  
                  } else if (Pixastic.Client.isIE()) {
                          params.image.style.filter += " progid:DXImageTransform.Microsoft.emboss()";
                          return true;
                  }
          },
          checkSupport : function() {
                  return (Pixastic.Client.hasCanvasImageData() || Pixastic.Client.isIE());
          }
  
  }