// Effect extensions

// Changing font color instead of background color
Effect.HighlightFont = Class.create(Effect.Base, {
  initialize: function(element) {
    this.element = $(element);
    if (!this.element) throw(Effect._elementDoesNotExistError);
    var options = Object.extend({ startcolor: '#ffff99' }, arguments[1] || { });
    this.start(options);
  },
  setup: function() {
    // Prevent executing on elements not in the layout flow
    if (this.element.getStyle('display')=='none') { this.cancel(); return; }
    // Disable background image during the effect
    this.oldStyle = { };
    if (!this.options.keepBackgroundImage) {
      this.oldStyle.backgroundImage = this.element.getStyle('background-image');
      this.element.setStyle({backgroundImage: 'none'});
    }
    if (!this.options.endcolor)
      this.options.endcolor = this.element.getStyle('color').parseColor('#ffffff');
    if (!this.options.restorecolor)
      this.options.restorecolor = this.element.getStyle('color');
    // init color calculations
    this._base  = $R(0,2).map(function(i){ return parseInt(this.options.startcolor.slice(i*2+1,i*2+3),16) }.bind(this));
    this._delta = $R(0,2).map(function(i){ return parseInt(this.options.endcolor.slice(i*2+1,i*2+3),16)-this._base[i] }.bind(this));
  },
  update: function(position) {
  	this.element.setStyle({color: $R(0,2).inject('#',function(m,v,i){
      return m+((this._base[i]+(this._delta[i]*position)).round().toColorPart()); }.bind(this)) });
  },
  finish: function() {
    this.element.setStyle(Object.extend(this.oldStyle, {
    color: this.options.restorecolor
    }));
  }
});