animation.js

/*
Copyright (c) 2007, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 2.2.0
*/
/*
Copyright (c) 2006, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
*/

/**
 * The animation module provides allows effects to be added to HTMLElements.
 * @module animation
 * @requires yahoo, event, dom
 */

/**
 *
 * Base animation class that provides the interface for building animated effects.
 * <p>Usage: var myAnim = new YAHOO.util.Anim(el, { width: { from: 10, to: 100 } }, 1, YAHOO.util.Easing.easeOut);</p>
 * @class Anim
 * @namespace YAHOO.util
 * @requires YAHOO.util.AnimMgr
 * @requires YAHOO.util.Easing
 * @requires YAHOO.util.Dom
 * @requires YAHOO.util.Event
 * @requires YAHOO.util.CustomEvent
 * @constructor
 * @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.Anim = function(el, attributes, duration, method) {
    if (el) {
        this.init(el, attributes, duration, method); 
    }
};

YAHOO.util.Anim.prototype = {
    /**
     * Provides a readable name for the Anim instance.
     * @method toString
     * @return {String}
     */
    toString: function() {
        var el = this.getEl();
        var id = el.id || el.tagName;
        return ("Anim " + id);
    },
    
    patterns: { // cached for performance
        noNegatives:        /width|height|opacity|padding/i, // keep at zero or above
        offsetAttribute:  /^((width|height)|(top|left))$/, // use offsetValue as default
        defaultUnit:        /width|height|top$|bottom$|left$|right$/i, // use 'px' by default
        offsetUnit:         /\d+(em|%|en|ex|pt|in|cm|mm|pc)$/i // IE may return these, so convert these to offset
    },
    
    /**
     * Returns the value computed by the animation's "method".
     * @method doMethod
     * @param {String} attr The name of the attribute.
     * @param {Number} start The value this attribute should start from for this animation.
     * @param {Number} end  The value this attribute should end at for this animation.
     * @return {Number} The Value to be applied to the attribute.
     */
    doMethod: function(attr, start, end) {
        return this.method(this.currentFrame, start, end - start, this.totalFrames);
    },
    
    /**
     * Applies a value to an attribute.
     * @method setAttribute
     * @param {String} attr The name of the attribute.
     * @param {Number} val The value to be applied to the attribute.
     * @param {String} unit The unit ('px', '%', etc.) of the value.
     */
    setAttribute: function(attr, val, unit) {
        if ( this.patterns.noNegatives.test(attr) ) {
            val = (val > 0) ? val : 0;
        }

        YAHOO.util.Dom.setStyle(this.getEl(), attr, val + unit);
    },                        
    
    /**
     * Returns current value of the attribute.
     * @method getAttribute
     * @param {String} attr The name of the attribute.
     * @return {Number} val The current value of the attribute.
     */
    getAttribute: function(attr) {
        var el = this.getEl();
        var val = YAHOO.util.Dom.getStyle(el, attr);

        if (val !== 'auto' && !this.patterns.offsetUnit.test(val)) {
            return parseFloat(val);
        }
        
        var a = this.patterns.offsetAttribute.exec(attr) || [];
        var pos = !!( a[3] ); // top or left
        var box = !!( a[2] ); // width or height
        
        // use offsets for width/height and abs pos top/left
        if ( box || (YAHOO.util.Dom.getStyle(el, 'position') == 'absolute' && pos) ) {
            val = el['offset' + a[0].charAt(0).toUpperCase() + a[0].substr(1)];
        } else { // default to zero for other 'auto'
            val = 0;
        }

        return val;
    },
    
    /**
     * Returns the unit to use when none is supplied.
     * @method getDefaultUnit
     * @param {attr} attr The name of the attribute.
     * @return {String} The default unit to be used.
     */
    getDefaultUnit: function(attr) {
         if ( this.patterns.defaultUnit.test(attr) ) {
            return 'px';
         }
         
         return '';
    },
        
    /**
     * Sets the actual values to be used during the animation.  Should only be needed for subclass use.
     * @method setRuntimeAttribute
     * @param {Object} attr The attribute object
     * @private 
     */
    setRuntimeAttribute: function(attr) {
        var start;
        var end;
        var attributes = this.attributes;

        this.runtimeAttributes[attr] = {};
        
        var isset = function(prop) {
            return (typeof prop !== 'undefined');
        };
        
        if ( !isset(attributes[attr]['to']) && !isset(attributes[attr]['by']) ) {
            return false; // note return; nothing to animate to
        }
        
        start = ( isset(attributes[attr]['from']) ) ? attributes[attr]['from'] : this.getAttribute(attr);

        // To beats by, per SMIL 2.1 spec
        if ( isset(attributes[attr]['to']) ) {
            end = attributes[attr]['to'];
        } else if ( isset(attributes[attr]['by']) ) {
            if (start.constructor == Array) {
                end = [];
                for (var i = 0, len = start.length; i < len; ++i) {
                    end[i] = start[i] + attributes[attr]['by'][i];
                }
            } else {
                end = start + attributes[attr]['by'];
            }
        }
        
        this.runtimeAttributes[attr].start = start;
        this.runtimeAttributes[attr].end = end;

        // set units if needed
        this.runtimeAttributes[attr].unit = ( isset(attributes[attr].unit) ) ? attributes[attr]['unit'] : this.getDefaultUnit(attr);
    },

    /**
     * Constructor for Anim instance.
     * @method init
     * @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)
     */ 
    init: function(el, attributes, duration, method) {
        /**
         * Whether or not the animation is running.
         * @property isAnimated
         * @private
         * @type Boolean
         */
        var isAnimated = false;
        
        /**
         * A Date object that is created when the animation begins.
         * @property startTime
         * @private
         * @type Date
         */
        var startTime = null;
        
        /**
         * The number of frames this animation was able to execute.
         * @property actualFrames
         * @private
         * @type Int
         */
        var actualFrames = 0; 

        /**
         * The element to be animated.
         * @property el
         * @private
         * @type HTMLElement
         */
        el = YAHOO.util.Dom.get(el);
        
        /**
         * The collection of attributes to be animated.  
         * Each attribute must have at least a "to" or "by" defined in order to animate.  
         * If "to" is supplied, the animation will end with the attribute at that value.  
         * If "by" is supplied, the animation will end at that value plus its starting value. 
         * If both are supplied, "to" is used, and "by" is ignored. 
         * Optional additional member include "from" (the value the attribute should start animating from, defaults to current value), and "unit" (the units to apply to the values).
         * @property attributes
         * @type Object
         */
        this.attributes = attributes || {};
        
        /**
         * The length of the animation.  Defaults to "1" (second).
         * @property duration
         * @type Number
         */
        this.duration = duration || 1;
        
        /**
         * The method that will provide values to the attribute(s) during the animation. 
         * Defaults to "YAHOO.util.Easing.easeNone".
         * @property method
         * @type Function
         */
        this.method = method || YAHOO.util.Easing.easeNone;

        /**
         * Whether or not the duration should be treated as seconds.
         * Defaults to true.
         * @property useSeconds
         * @type Boolean
         */
        this.useSeconds = true; // default to seconds
        
        /**
         * The location of the current animation on the timeline.
         * In time-based animations, this is used by AnimMgr to ensure the animation finishes on time.
         * @property currentFrame
         * @type Int
         */
        this.currentFrame = 0;
        
        /**
         * The total number of frames to be executed.
         * In time-based animations, this is used by AnimMgr to ensure the animation finishes on time.
         * @property totalFrames
         * @type Int
         */
        this.totalFrames = YAHOO.util.AnimMgr.fps;
        
        
        /**
         * Returns a reference to the animated element.
         * @method getEl
         * @return {HTMLElement}
         */
        this.getEl = function() { return el; };
        
        /**
         * Checks whether the element is currently animated.
         * @method isAnimated
         * @return {Boolean} current value of isAnimated.     
         */
        this.isAnimated = function() {
            return isAnimated;
        };
        
        /**
         * Returns the animation start time.
         * @method getStartTime
         * @return {Date} current value of startTime.      
         */
        this.getStartTime = function() {
            return startTime;
        };        
        
        this.runtimeAttributes = {};
        
        
        
        /**
         * Starts the animation by registering it with the animation manager. 
         * @method animate  
         */
        this.animate = function() {
            if ( this.isAnimated() ) {
                return false;
            }
            
            this.currentFrame = 0;
            
            this.totalFrames = ( this.useSeconds ) ? Math.ceil(YAHOO.util.AnimMgr.fps * this.duration) : this.duration;
    
            YAHOO.util.AnimMgr.registerElement(this);
        };
          
        /**
         * Stops the animation.  Normally called by AnimMgr when animation completes.
         * @method stop
         * @param {Boolean} finish (optional) If true, animation will jump to final frame.
         */ 
        this.stop = function(finish) {
            if (finish) {
                 this.currentFrame = this.totalFrames;
                 this._onTween.fire();
            }
            YAHOO.util.AnimMgr.stop(this);
        };
        
        var onStart = function() {            
            this.onStart.fire();
            
            this.runtimeAttributes = {};
            for (var attr in this.attributes) {
                this.setRuntimeAttribute(attr);
            }
            
            isAnimated = true;
            actualFrames = 0;
            startTime = new Date(); 
        };
        
        /**
         * Feeds the starting and ending values for each animated attribute to doMethod once per frame, then applies the resulting value to the attribute(s).
         * @private
         */
         
        var onTween = function() {
            var data = {
                duration: new Date() - this.getStartTime(),
                currentFrame: this.currentFrame
            };
            
            data.toString = function() {
                return (
                    'duration: ' + data.duration +
                    ', currentFrame: ' + data.currentFrame
                );
            };
            
            this.onTween.fire(data);
            
            var runtimeAttributes = this.runtimeAttributes;
            
            for (var attr in runtimeAttributes) {
                this.setAttribute(attr, this.doMethod(attr, runtimeAttributes[attr].start, runtimeAttributes[attr].end), runtimeAttributes[attr].unit); 
            }
            
            actualFrames += 1;
        };
        
        var onComplete = function() {
            var actual_duration = (new Date() - startTime) / 1000 ;
            
            var data = {
                duration: actual_duration,
                frames: actualFrames,
                fps: actualFrames / actual_duration
            };
            
            data.toString = function() {
                return (
                    'duration: ' + data.duration +
                    ', frames: ' + data.frames +
                    ', fps: ' + data.fps
                );
            };
            
            isAnimated = false;
            actualFrames = 0;
            this.onComplete.fire(data);
        };
        
        /**
         * Custom event that fires after onStart, useful in subclassing
         * @private
         */    
        this._onStart = new YAHOO.util.CustomEvent('_start', this, true);

        /**
         * Custom event that fires when animation begins
         * Listen via subscribe method (e.g. myAnim.onStart.subscribe(someFunction)
         * @event onStart
         */    
        this.onStart = new YAHOO.util.CustomEvent('start', this);
        
        /**
         * Custom event that fires between each frame
         * Listen via subscribe method (e.g. myAnim.onTween.subscribe(someFunction)
         * @event onTween
         */
        this.onTween = new YAHOO.util.CustomEvent('tween', this);
        
        /**
         * Custom event that fires after onTween
         * @private
         */
        this._onTween = new YAHOO.util.CustomEvent('_tween', this, true);
        
        /**
         * Custom event that fires when animation ends
         * Listen via subscribe method (e.g. myAnim.onComplete.subscribe(someFunction)
         * @event onComplete
         */
        this.onComplete = new YAHOO.util.CustomEvent('complete', this);
        /**
         * Custom event that fires after onComplete
         * @private
         */
        this._onComplete = new YAHOO.util.CustomEvent('_complete', this, true);

        this._onStart.subscribe(onStart);
        this._onTween.subscribe(onTween);
        this._onComplete.subscribe(onComplete);
    }
};

/**
 * Handles animation queueing and threading.
 * Used by Anim and subclasses.
 * @class AnimMgr
 * @namespace YAHOO.util
 */
YAHOO.util.AnimMgr = new function() {
    /** 
     * Reference to the animation Interval.
     * @property thread
     * @private
     * @type Int
     */
    var thread = null;
    
    /** 
     * The current queue of registered animation objects.
     * @property queue
     * @private
     * @type Array
     */    
    var queue = [];

    /** 
     * The number of active animations.
     * @property tweenCount
     * @private
     * @type Int
     */        
    var tweenCount = 0;

    /** 
     * Base frame rate (frames per second). 
     * Arbitrarily high for better x-browser calibration (slower browsers drop more frames).
     * @property fps
     * @type Int
     * 
     */
    this.fps = 1000;

    /** 
     * Interval delay in milliseconds, defaults to fastest possible.
     * @property delay
     * @type Int
     * 
     */
    this.delay = 1;

    /**
     * Adds an animation instance to the animation queue.
     * All animation instances must be registered in order to animate.
     * @method registerElement
     * @param {object} tween The Anim instance to be be registered
     */
    this.registerElement = function(tween) {
        queue[queue.length] = tween;
        tweenCount += 1;
        tween._onStart.fire();
        this.start();
    };
    
    /**
     * removes an animation instance from the animation queue.
     * All animation instances must be registered in order to animate.
     * @method unRegister
     * @param {object} tween The Anim instance to be be registered
     * @param {Int} index The index of the Anim instance
     * @private
     */
    this.unRegister = function(tween, index) {
        tween._onComplete.fire();
        index = index || getIndex(tween);
        if (index != -1) {
            queue.splice(index, 1);
        }
        
        tweenCount -= 1;
        if (tweenCount <= 0) {
            this.stop();
        }
    };
    
    /**
     * Starts the animation thread.
	* Only one thread can run at a time.
     * @method start
     */    
    this.start = function() {
        if (thread === null) {
            thread = setInterval(this.run, this.delay);
        }
    };

    /**
     * Stops the animation thread or a specific animation instance.
     * @method stop
     * @param {object} tween A specific Anim instance to stop (optional)
     * If no instance given, Manager stops thread and all animations.
     */    
    this.stop = function(tween) {
        if (!tween) {
            clearInterval(thread);
            
            for (var i = 0, len = queue.length; i < len; ++i) {
                if ( queue[0].isAnimated() ) {
                    this.unRegister(queue[0], 0);  
                }
            }

            queue = [];
            thread = null;
            tweenCount = 0;
        }
        else {
            this.unRegister(tween);
        }
    };
    
    /**
     * Called per Interval to handle each animation frame.
     * @method run
     */    
    this.run = function() {
        for (var i = 0, len = queue.length; i < len; ++i) {
            var tween = queue[i];
            if ( !tween || !tween.isAnimated() ) { continue; }

            if (tween.currentFrame < tween.totalFrames || tween.totalFrames === null)
            {
                tween.currentFrame += 1;
                
                if (tween.useSeconds) {
                    correctFrame(tween);
                }
                tween._onTween.fire();          
            }
            else { YAHOO.util.AnimMgr.stop(tween, i); }
        }
    };
    
    var getIndex = function(anim) {
        for (var i = 0, len = queue.length; i < len; ++i) {
            if (queue[i] == anim) {
                return i; // note return;
            }
        }
        return -1;
    };
    
    /**
     * On the fly frame correction to keep animation on time.
     * @method correctFrame
     * @private
     * @param {Object} tween The Anim instance being corrected.
     */
    var correctFrame = function(tween) {
        var frames = tween.totalFrames;
        var frame = tween.currentFrame;
        var expected = (tween.currentFrame * tween.duration * 1000 / tween.totalFrames);
        var elapsed = (new Date() - tween.getStartTime());
        var tweak = 0;
        
        if (elapsed < tween.duration * 1000) { // check if falling behind
            tweak = Math.round((elapsed / expected - 1) * tween.currentFrame);
        } else { // went over duration, so jump to end
            tweak = frames - (frame + 1); 
        }
        if (tweak > 0 && isFinite(tweak)) { // adjust if needed
            if (tween.currentFrame + tweak >= frames) {// dont go past last frame
                tweak = frames - (frame + 1);
            }
            
            tween.currentFrame += tweak;      
        }
    };
};
/**
 * Used to calculate Bezier splines for any number of control points.
 * @class Bezier
 * @namespace YAHOO.util
 *
 */
YAHOO.util.Bezier = new function() {
    /**
     * Get the current position of the animated element based on t.
     * Each point is an array of "x" and "y" values (0 = x, 1 = y)
     * At least 2 points are required (start and end).
     * First point is start. Last point is end.
     * Additional control points are optional.     
     * @method getPosition
     * @param {Array} points An array containing Bezier points
     * @param {Number} t A number between 0 and 1 which is the basis for determining current position
     * @return {Array} An array containing int x and y member data
     */
    this.getPosition = function(points, t) {  
        var n = points.length;
        var tmp = [];

        for (var i = 0; i < n; ++i){
            tmp[i] = [points[i][0], points[i][1]]; // save input
        }
        
        for (var j = 1; j < n; ++j) {
            for (i = 0; i < n - j; ++i) {
                tmp[i][0] = (1 - t) * tmp[i][0] + t * tmp[parseInt(i + 1, 10)][0];
                tmp[i][1] = (1 - t) * tmp[i][1] + t * tmp[parseInt(i + 1, 10)][1]; 
            }
        }
    
        return [ tmp[0][0], tmp[0][1] ]; 
    
    };
};
(function() {
/**
 * Anim subclass for color transitions.
 * <p>Usage: <code>var myAnim = new Y.ColorAnim(el, { backgroundColor: { from: '#FF0000', to: '#FFFFFF' } }, 1, Y.Easing.easeOut);</code> Color values can be specified with either 112233, #112233, 
 * [255,255,255], or rgb(255,255,255)</p>
 * @class ColorAnim
 * @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
 * @constructor
 * @extends YAHOO.util.Anim
 * @param {HTMLElement | String} 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.ColorAnim = function(el, attributes, duration,  method) {
        YAHOO.util.ColorAnim.superclass.constructor.call(this, el, attributes, duration, method);
    };
    
    YAHOO.extend(YAHOO.util.ColorAnim, YAHOO.util.Anim);
    
    // shorthand
    var Y = YAHOO.util;
    var superclass = Y.ColorAnim.superclass;
    var proto = Y.ColorAnim.prototype;
    
    proto.toString = function() {
        var el = this.getEl();
        var id = el.id || el.tagName;
        return ("ColorAnim " + id);
    };

    proto.patterns.color = /color$/i;
    proto.patterns.rgb            = /^rgb\(([0-9]+)\s*,\s*([0-9]+)\s*,\s*([0-9]+)\)$/i;
    proto.patterns.hex            = /^#?([0-9A-F]{2})([0-9A-F]{2})([0-9A-F]{2})$/i;
    proto.patterns.hex3          = /^#?([0-9A-F]{1})([0-9A-F]{1})([0-9A-F]{1})$/i;
    proto.patterns.transparent = /^transparent|rgba\(0, 0, 0, 0\)$/; // need rgba for safari
    
    /**
     * Attempts to parse the given string and return a 3-tuple.
     * @method parseColor
     * @param {String} s The string to parse.
     * @return {Array} The 3-tuple of rgb values.
     */
    proto.parseColor = function(s) {
        if (s.length == 3) { return s; }
    
        var c = this.patterns.hex.exec(s);
        if (c && c.length == 4) {
            return [ parseInt(c[1], 16), parseInt(c[2], 16), parseInt(c[3], 16) ];
        }
    
        c = this.patterns.rgb.exec(s);
        if (c && c.length == 4) {
            return [ parseInt(c[1], 10), parseInt(c[2], 10), parseInt(c[3], 10) ];
        }
    
        c = this.patterns.hex3.exec(s);
        if (c && c.length == 4) {
            return [ parseInt(c[1] + c[1], 16), parseInt(c[2] + c[2], 16), parseInt(c[3] + c[3], 16) ];
        }
        
        return null;
    };

    proto.getAttribute = function(attr) {
        var el = this.getEl();
        if (  this.patterns.color.test(attr) ) {
            var val = YAHOO.util.Dom.getStyle(el, attr);
            
            if (this.patterns.transparent.test(val)) { // bgcolor default
                var parent = el.parentNode; // try and get from an ancestor
                val = Y.Dom.getStyle(parent, attr);
            
                while (parent && this.patterns.transparent.test(val)) {
                    parent = parent.parentNode;
                    val = Y.Dom.getStyle(parent, attr);
                    if (parent.tagName.toUpperCase() == 'HTML') {
                        val = '#fff';
                    }
                }
            }
        } else {
            val = superclass.getAttribute.call(this, attr);
        }

        return val;
    };
    
    proto.doMethod = function(attr, start, end) {
        var val;
    
        if ( this.patterns.color.test(attr) ) {
            val = [];
            for (var i = 0, len = start.length; i < len; ++i) {
                val[i] = superclass.doMethod.call(this, attr, start[i], end[i]);
            }
            
            val = 'rgb('+Math.floor(val[0])+','+Math.floor(val[1])+','+Math.floor(val[2])+')';
        }
        else {
            val = superclass.doMethod.call(this, attr, start, end);
        }

        return val;
    };

    proto.setRuntimeAttribute = function(attr) {
        superclass.setRuntimeAttribute.call(this, attr);
        
        if ( this.patterns.color.test(attr) ) {
            var attributes = this.attributes;
            var start = this.parseColor(this.runtimeAttributes[attr].start);
            var end = this.parseColor(this.runtimeAttributes[attr].end);
            // fix colors if going "by"
            if ( typeof attributes[attr]['to'] === 'undefined' && typeof attributes[attr]['by'] !== 'undefined' ) {
                end = this.parseColor(attributes[attr].by);
            
                for (var i = 0, len = start.length; i < len; ++i) {
                    end[i] = start[i] + end[i];
                }
            }
            
            this.runtimeAttributes[attr].start = start;
            this.runtimeAttributes[attr].end = end;
        }
    };
})();
/*
TERMS OF USE - EASING EQUATIONS
Open source under the BSD License.
Copyright 2001 Robert Penner All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 * Neither the name of the author nor the names of contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/**
 * Singleton that determines how an animation proceeds from start to end.
 * @class Easing
 * @namespace YAHOO.util
*/

YAHOO.util.Easing = {

    /**
     * Uniform speed between points.
     * @method easeNone
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @return {Number} The computed value for the current animation frame
     */
    easeNone: function (t, b, c, d) {
    	return c*t/d + b;
    },
    
    /**
     * Begins slowly and accelerates towards end. (quadratic)
     * @method easeIn
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @return {Number} The computed value for the current animation frame
     */
    easeIn: function (t, b, c, d) {
    	return c*(t/=d)*t + b;
    },

    /**
     * Begins quickly and decelerates towards end.  (quadratic)
     * @method easeOut
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @return {Number} The computed value for the current animation frame
     */
    easeOut: function (t, b, c, d) {
    	return -c *(t/=d)*(t-2) + b;
    },
    
    /**
     * Begins slowly and decelerates towards end. (quadratic)
     * @method easeBoth
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @return {Number} The computed value for the current animation frame
     */
    easeBoth: function (t, b, c, d) {
    	if ((t/=d/2) < 1) {
            return c/2*t*t + b;
        }
        
    	return -c/2 * ((--t)*(t-2) - 1) + b;
    },
    
    /**
     * Begins slowly and accelerates towards end. (quartic)
     * @method easeInStrong
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @return {Number} The computed value for the current animation frame
     */
    easeInStrong: function (t, b, c, d) {
    	return c*(t/=d)*t*t*t + b;
    },
    
    /**
     * Begins quickly and decelerates towards end.  (quartic)
     * @method easeOutStrong
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @return {Number} The computed value for the current animation frame
     */
    easeOutStrong: function (t, b, c, d) {
    	return -c * ((t=t/d-1)*t*t*t - 1) + b;
    },
    
    /**
     * Begins slowly and decelerates towards end. (quartic)
     * @method easeBothStrong
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @return {Number} The computed value for the current animation frame
     */
    easeBothStrong: function (t, b, c, d) {
    	if ((t/=d/2) < 1) {
            return c/2*t*t*t*t + b;
        }
        
    	return -c/2 * ((t-=2)*t*t*t - 2) + b;
    },

    /**
     * Snap in elastic effect.
     * @method elasticIn
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @param {Number} a Amplitude (optional)
     * @param {Number} p Period (optional)
     * @return {Number} The computed value for the current animation frame
     */

    elasticIn: function (t, b, c, d, a, p) {
    	if (t == 0) {
            return b;
        }
        if ( (t /= d) == 1 ) {
            return b+c;
        }
        if (!p) {
            p=d*.3;
        }
        
    	if (!a || a < Math.abs(c)) {
            a = c; 
            var s = p/4;
        }
    	else {
            var s = p/(2*Math.PI) * Math.asin (c/a);
        }
        
    	return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
    },

    /**
     * Snap out elastic effect.
     * @method elasticOut
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @param {Number} a Amplitude (optional)
     * @param {Number} p Period (optional)
     * @return {Number} The computed value for the current animation frame
     */
    elasticOut: function (t, b, c, d, a, p) {
    	if (t == 0) {
            return b;
        }
        if ( (t /= d) == 1 ) {
            return b+c;
        }
        if (!p) {
            p=d*.3;
        }
        
    	if (!a || a < Math.abs(c)) {
            a = c;
            var s = p / 4;
        }
    	else {
            var s = p/(2*Math.PI) * Math.asin (c/a);
        }
        
    	return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
    },
    
    /**
     * Snap both elastic effect.
     * @method elasticBoth
     * @param {Number} t Time value used to compute current value
     * @param {Number} b Starting value
     * @param {Number} c Delta between start and end values
     * @param {Number} d Total length of animation
     * @param {Number} a Amplitude (optional)
     * @param {Number} p Period (optional)
     * @return {Number} The computed value for the current animation frame
     */
    elasticBoth: function (t, b, c, d, a, p) {
    	if (t == 0) {
            return b;
        }
        
        if ( (t /= d/2) == 2 ) {
            return b+c;
        }
        
        if (!p) {
            p = d*(.3*1.5);
        }