Yahoo! UI Library

(function() {
/**
 * Anim subclass for moving elements along a path defined by the "points" 
 * member of "attributes".  All "points" are arrays with x, y coordinates.
 * <p>Usage: <code>var myAnim = new YAHOO.util.Motion(el, { points: { to: [800, 800] } }, 1, YAHOO.util.Easing.easeOut);</code></p>
 * @class Motion
 * @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 
 * @constructor
 * @extends YAHOO.util.Anim
 * @param {String | 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)
 */
    YAHOO.util.Motion = function(el, attributes, duration,  method) {
        if (el) { // dont break existing subclasses not using YAHOO.extend
            YAHOO.util.Motion.superclass.constructor.call(this, el, attributes, duration, method);
        }
    };

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

    proto.toString = function() {
        var el = this.getEl();
        var id = el.id || el.tagName;
        return ("Motion " + id);
    };
    
    proto.patterns.points = /^points$/i;
    
    proto.setAttribute = function(attr, val, unit) {
        if (  this.patterns.points.test(attr) ) {
            unit = unit || 'px';
            superclass.setAttribute.call(this, 'left', val[0], unit);
            superclass.setAttribute.call(this, 'top', val[1], unit);
        } else {
            superclass.setAttribute.call(this, attr, val, unit);
        }
    };

    proto.getAttribute = function(attr) {
        if (  this.patterns.points.test(attr) ) {
            var val = [
                superclass.getAttribute.call(this, 'left'),
                superclass.getAttribute.call(this, 'top')
            ];
        } else {
            val = superclass.getAttribute.call(this, attr);
        }

        return val;
    };

    proto.doMethod = function(attr, start, end) {
        var val = null;

        if ( this.patterns.points.test(attr) ) {
            var t = this.method(this.currentFrame, 0, 100, this.totalFrames) / 100;				
            val = Y.Bezier.getPosition(this.runtimeAttributes[attr], t);
        } else {
            val = superclass.doMethod.call(this, attr, start, end);
        }
        return val;
    };

    proto.setRuntimeAttribute = function(attr) {
        if ( this.patterns.points.test(attr) ) {
            var el = this.getEl();
            var attributes = this.attributes;
            var start;
            var control = attributes['points']['control'] || [];
            var end;
            var i, len;
            
            if (control.length > 0 && !(control[0] instanceof Array) ) { // could be single point or array of points
                control = [control];
            } else { // break reference to attributes.points.control
                var tmp = []; 
                for (i = 0, len = control.length; i< len; ++i) {
                    tmp[i] = control[i];
                }
                control = tmp;
            }

            if (Y.Dom.getStyle(el, 'position') == 'static') { // default to relative
                Y.Dom.setStyle(el, 'position', 'relative');
            }
    
            if ( isset(attributes['points']['from']) ) {
                Y.Dom.setXY(el, attributes['points']['from']); // set position to from point
            } 
            else { Y.Dom.setXY( el, Y.Dom.getXY(el) ); } // set it to current position
            
            start = this.getAttribute('points'); // get actual top & left
            
            // TO beats BY, per SMIL 2.1 spec
            if ( isset(attributes['points']['to']) ) {
                end = translateValues.call(this, attributes['points']['to'], start);
                
                var pageXY = Y.Dom.getXY(this.getEl());
                for (i = 0, len = control.length; i < len; ++i) {
                    control[i] = translateValues.call(this, control[i], start);
                }

                
            } else if ( isset(attributes['points']['by']) ) {
                end = [ start[0] + attributes['points']['by'][0], start[1] + attributes['points']['by'][1] ];
                
                for (i = 0, len = control.length; i < len; ++i) {
                    control[i] = [ start[0] + control[i][0], start[1] + control[i][1] ];
                }
            }

            this.runtimeAttributes[attr] = [start];
            
            if (control.length > 0) {
                this.runtimeAttributes[attr] = this.runtimeAttributes[attr].concat(control); 
            }

            this.runtimeAttributes[attr][this.runtimeAttributes[attr].length] = end;
        }
        else {
            superclass.setRuntimeAttribute.call(this, attr);
        }
    };
    
    var translateValues = function(val, start) {
        var pageXY = Y.Dom.getXY(this.getEl());
        val = [ val[0] - pageXY[0] + start[0], val[1] - pageXY[1] + start[1] ];

        return val; 
    };
    
    var isset = function(prop) {
        return (typeof prop !== 'undefined');
    };
})();