/*
   * Pixastic Lib - Brightness/Contrast 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.brightness = {
  
          process : function(params) {
  
                  var brightness = parseInt(params.options.brightness,10) || 0;
                  var contrast = parseFloat(params.options.contrast)||0;
                  var legacy = !!(params.options.legacy);
  
                  if (legacy) {
                          brightness = Math.min(150,Math.max(-150,brightness));
                  } else {
                          var brightMul = 1 + Math.min(150,Math.max(-150,brightness)) / 150;
                  }
                  contrast = Math.max(0,contrast+1);
  
                  if (Pixastic.Client.hasCanvasImageData()) {
                          var data = Pixastic.prepareData(params);
                          var rect = params.options.rect;
                          var w = rect.width;
                          var h = rect.height;
  
                          var p = w*h;
                          var pix = p*4, pix1, pix2;
  
                          var mul, add;
                          if (contrast != 1) {
                                  if (legacy) {
                                          mul = contrast;
                                          add = (brightness - 128) * contrast + 128;
                                  } else {
                                          mul = brightMul * contrast;
                                          add = - contrast * 128 + 128;
                                  }
                          } else {
                                  if (legacy) {
                                          mul = 1;
                                          add = brightness;
                                  } else {
                                          mul = brightMul;
                                          add = 0;
                                  }
                          }
                          var r, g, b;
                          while (p--) {
                                  if ((r = data[pix-=4] * mul + add) > 255 )
                                          data[pix] = 255;
                                  else if (r < 0)
                                          data[pix] = 0;
                                  else
                                           data[pix] = r;
  
                                  if ((g = data[pix1=pix+1] * mul + add) > 255 ) 
                                          data[pix1] = 255;
                                  else if (g < 0)
                                          data[pix1] = 0;
                                  else
                                          data[pix1] = g;
  
                                  if ((b = data[pix2=pix+2] * mul + add) > 255 ) 
                                          data[pix2] = 255;
                                  else if (b < 0)
                                          data[pix2] = 0;
                                  else
                                          data[pix2] = b;
                          }
                          return true;
                  }
          },
          checkSupport : function() {
                  return Pixastic.Client.hasCanvasImageData();
          }
  }