Yahoo! UI Library

(function() {
/**
 * Anim subclass for scrolling elements to a position defined by the "scroll"
 * member of "attributes".  All "scroll" members are arrays with x, y scroll positions.
 * <p>Usage: <code>var myAnim = new YAHOO.util.Scroll(el, { scroll: { to: [0, 800] } }, 1, YAHOO.util.Easing.easeOut);</code></p>
 * @class Scroll
 * @namespace YAHOO.util
 * @requires YAHOO.util.Anim
 * @requires YAHOO.util.AnimMgr
 * @requires YAHOO.util.Easing
 * @requires YAHOO.util.Bezier
 * @requires YAHOO.util.Dom
 * @requires YAHOO.util.Event
 * @requires YAHOO.util.CustomEvent 
 * @extends YAHOO.util.ColorAnim
 * @constructor
 * @param {String or HTMLElement} el Reference to the element that will be animated
 * @param {Object} attributes The attribute(s) to be animated.  
 * Each attribute is an object with at minimum a "to" or "by" member defined.  
 * Additional optional members are "from" (defaults to current value), "units" (defaults to "px").  
 * All attribute names use camelCase.
 * @param {Number} duration (optional, defaults to 1 second) Length of animation (frames or seconds), defaults to time-based
 * @param {Function} method (optional, defaults to YAHOO.util.Easing.easeNone) Computes the values that are applied to the attributes per frame (generally a YAHOO.util.Easing method)
 */
    var Scroll = function(el, attributes, duration,  method) {
        if (el) { // dont break existing subclasses not using YAHOO.extend
            Scroll.superclass.constructor.call(this, el, attributes, duration, method);
        }
    };

    Scroll.NAME = 'Scroll';

    // shorthand
    var Y = YAHOO.util;
    YAHOO.extend(Scroll, Y.ColorAnim);
    
    var superclass = Scroll.superclass;
    var proto = Scroll.prototype;

    proto.doMethod = function(attr, start, end) {
        var val = null;
    
        if (attr == 'scroll') {
            val = [
                this.method(this.currentFrame, start[0], end[0] - start[0], this.totalFrames),
                this.method(this.currentFrame, start[1], end[1] - start[1], this.totalFrames)
            ];
            
        } else {
            val = superclass.doMethod.call(this, attr, start, end);
        }
        return val;
    };

    proto.getAttribute = function(attr) {
        var val = null;
        var el = this.getEl();
        
        if (attr == 'scroll') {
            val = [ el.scrollLeft, el.scrollTop ];
        } else {
            val = superclass.getAttribute.call(this, attr);
        }
        
        return val;
    };

    proto.setAttribute = function(attr, val, unit) {
        var el = this.getEl();
        
        if (attr == 'scroll') {
            el.scrollLeft = val[0];
            el.scrollTop = val[1];
        } else {
            superclass.setAttribute.call(this, attr, val, unit);
        }
    };

    Y.Scroll = Scroll;
})();