/*
* Effect.Morphpos - an extension to Script.aculo.us' Effect.Morph 
* Version 1
* Based on code lifted from Script.Aculo.Us version 1.8.1
* Amendments by Anthony Doherty 2008
* http://codeandeffect.co.uk/blog
*/
Effect.Morphbgpos = Class.create(Effect.Base, {
 
  initialize: function(element) {
    this.element = $(element);
    if (!this.element) throw(Effect._elementDoesNotExistError);
    var options = Object.extend({
      style: { }
    }, arguments[1] || { });
    this.style = options.style.parseStyle();
    this.start(options);
  },
  
  setup: function(){
 
    this.transforms = this.style.map(function(pair){
      var property = pair[0], value = pair[1], unit = null  ;
      var xpos, ypos
	  if (property != 'backgroundPosition') {
		return new Effect.Morph(this.element, { style: property+":"+value, duration: this.options.duration}  );
	}
     else if (Element.CSS_LENGTH.test(value)) {
          var components = value.match(/^([\+\-]?[0-9\.]+)(.*)$/);
		  var compo = value.match(/^([\+\-]?[0-9\.]+)(px)(.+)([\+\-]?[0-9\.]*)$/);
			 		 
			 	 	 xpos = parseFloat(compo[1]);
			  	     ypos = parseFloat(compo[3]);
			 
				  
		  
		  
          value = parseFloat(components[1]);
          unit = "px";
      }
	
		//get orginal x and y positions
		var originalValue = this.element.getStyle(property);
		
		var originalpositions = this.element.getStyle(property).match(/^([\+\-]?[0-9\.]+)(px)(.+)([\+\-]?[0-9\.]*)$/);
        var originalX = parseFloat(originalpositions[1]);
	    var originalY = parseFloat(originalpositions[3]);
      return { 
        style: property.camelize(), 
		originX: parseFloat(originalX || 0), 
		originY: parseFloat(originalY || 0), 
        originalValue: originalValue,
		targetX:  parseFloat(xpos || 0), 
		targetY:  parseFloat(ypos || 0), 
        targetValue:   value,
        unit: unit
		
      };
    }.bind(this)).reject(function(transform){
      return (
        (transform.originalValue == transform.targetValue) || (transform.unit  == (isNaN(transform.originalValue) || isNaN(transform.targetValue))
        )
      )
    });
  },
  update: function(position) {
    var style = { }, transform, i = this.transforms.length;
 
	while(i--)  {
	 
		 
      style[(transform = this.transforms[i]).style] =  
        (transform.originX +(transform.targetX - transform.originX) * position).toFixed(3) + "px" + " "+
		(transform.originY +(transform.targetY - transform.originY) * position).toFixed(3) + "px"  ;
        this.element.setStyle(style, true);
	    
		 }
  }
});