source: Dev/trunk/src/client/dojo/fx/easing.js

define(["../_base/lang"], function(lang){

// module:
//              dojo/fx/easing

var easingFuncs = {
        // summary:
        //              Collection of easing functions to use beyond the default
        //              `dojo._defaultEasing` function.
        // description:
        //              Easing functions are used to manipulate the iteration through
        //              an `dojo.Animation`s _Line. _Line being the properties of an Animation,
        //              and the easing function progresses through that Line determining
        //              how quickly (or slowly) it should go. Or more accurately: modify
        //              the value of the _Line based on the percentage of animation completed.
        //
        //              All functions follow a simple naming convention of "ease type" + "when".
        //              If the name of the function ends in Out, the easing described appears
        //              towards the end of the animation. "In" means during the beginning,
        //              and InOut means both ranges of the Animation will applied, both
        //              beginning and end.
        //
        //              One does not call the easing function directly, it must be passed to
        //              the `easing` property of an animation.
        // example:
        //      |       dojo.require("dojo.fx.easing");
        //      |       var anim = dojo.fadeOut({
        //      |               node: 'node',
        //      |               duration: 2000,
        //      |               //      note there is no ()
        //      |               easing: dojo.fx.easing.quadIn
        //      |       }).play();
        //

        linear: function(/* Decimal? */n){
                // summary:
                //              A linear easing function
                return n;
        },

        quadIn: function(/* Decimal? */n){
                return Math.pow(n, 2);
        },

        quadOut: function(/* Decimal? */n){
                return n * (n - 2) * -1;
        },

        quadInOut: function(/* Decimal? */n){
                n = n * 2;
                if(n < 1){ return Math.pow(n, 2) / 2; }
                return -1 * ((--n) * (n - 2) - 1) / 2;
        },

        cubicIn: function(/* Decimal? */n){
                return Math.pow(n, 3);
        },

        cubicOut: function(/* Decimal? */n){
                return Math.pow(n - 1, 3) + 1;
        },

        cubicInOut: function(/* Decimal? */n){
                n = n * 2;
                if(n < 1){ return Math.pow(n, 3) / 2; }
                n -= 2;
                return (Math.pow(n, 3) + 2) / 2;
        },

        quartIn: function(/* Decimal? */n){
                return Math.pow(n, 4);
        },

        quartOut: function(/* Decimal? */n){
                return -1 * (Math.pow(n - 1, 4) - 1);
        },

        quartInOut: function(/* Decimal? */n){
                n = n * 2;
                if(n < 1){ return Math.pow(n, 4) / 2; }
                n -= 2;
                return -1 / 2 * (Math.pow(n, 4) - 2);
        },

        quintIn: function(/* Decimal? */n){
                return Math.pow(n, 5);
        },

        quintOut: function(/* Decimal? */n){
                return Math.pow(n - 1, 5) + 1;
        },

        quintInOut: function(/* Decimal? */n){
                n = n * 2;
                if(n < 1){ return Math.pow(n, 5) / 2; }
                n -= 2;
                return (Math.pow(n, 5) + 2) / 2;
        },

        sineIn: function(/* Decimal? */n){
                return -1 * Math.cos(n * (Math.PI / 2)) + 1;
        },

        sineOut: function(/* Decimal? */n){
                return Math.sin(n * (Math.PI / 2));
        },

        sineInOut: function(/* Decimal? */n){
                return -1 * (Math.cos(Math.PI * n) - 1) / 2;
        },

        expoIn: function(/* Decimal? */n){
                return (n == 0) ? 0 : Math.pow(2, 10 * (n - 1));
        },

        expoOut: function(/* Decimal? */n){
                return (n == 1) ? 1 : (-1 * Math.pow(2, -10 * n) + 1);
        },

        expoInOut: function(/* Decimal? */n){
                if(n == 0){ return 0; }
                if(n == 1){ return 1; }
                n = n * 2;
                if(n < 1){ return Math.pow(2, 10 * (n - 1)) / 2; }
                --n;
                return (-1 * Math.pow(2, -10 * n) + 2) / 2;
        },

        circIn: function(/* Decimal? */n){
                return -1 * (Math.sqrt(1 - Math.pow(n, 2)) - 1);
        },

        circOut: function(/* Decimal? */n){
                n = n - 1;
                return Math.sqrt(1 - Math.pow(n, 2));
        },

        circInOut: function(/* Decimal? */n){
                n = n * 2;
                if(n < 1){ return -1 / 2 * (Math.sqrt(1 - Math.pow(n, 2)) - 1); }
                n -= 2;
                return 1 / 2 * (Math.sqrt(1 - Math.pow(n, 2)) + 1);
        },

        backIn: function(/* Decimal? */n){
                // summary:
                //              An easing function that starts away from the target,
                //              and quickly accelerates towards the end value.
                //
                //              Use caution when the easing will cause values to become
                //              negative as some properties cannot be set to negative values.
                var s = 1.70158;
                return Math.pow(n, 2) * ((s + 1) * n - s);
        },

        backOut: function(/* Decimal? */n){
                // summary:
                //              An easing function that pops past the range briefly, and slowly comes back.
                // description:
                //              An easing function that pops past the range briefly, and slowly comes back.
                //
                //              Use caution when the easing will cause values to become negative as some
                //              properties cannot be set to negative values.

                n = n - 1;
                var s = 1.70158;
                return Math.pow(n, 2) * ((s + 1) * n + s) + 1;
        },

        backInOut: function(/* Decimal? */n){
                // summary:
                //              An easing function combining the effects of `backIn` and `backOut`
                // description:
                //              An easing function combining the effects of `backIn` and `backOut`.
                //              Use caution when the easing will cause values to become negative
                //              as some properties cannot be set to negative values.
                var s = 1.70158 * 1.525;
                n = n * 2;
                if(n < 1){ return (Math.pow(n, 2) * ((s + 1) * n - s)) / 2; }
                n-=2;
                return (Math.pow(n, 2) * ((s + 1) * n + s) + 2) / 2;
        },

        elasticIn: function(/* Decimal? */n){
                // summary:
                //              An easing function the elastically snaps from the start value
                // description:
                //              An easing function the elastically snaps from the start value
                //
                //              Use caution when the elasticity will cause values to become negative
                //              as some properties cannot be set to negative values.
                if(n == 0 || n == 1){ return n; }
                var p = .3;
                var s = p / 4;
                n = n - 1;
                return -1 * Math.pow(2, 10 * n) * Math.sin((n - s) * (2 * Math.PI) / p);
        },

        elasticOut: function(/* Decimal? */n){
                // summary:
                //              An easing function that elasticly snaps around the target value,
                //              near the end of the Animation
                // description:
                //              An easing function that elasticly snaps around the target value,
                //              near the end of the Animation
                //
                //              Use caution when the elasticity will cause values to become
                //              negative as some properties cannot be set to negative values.
                if(n==0 || n == 1){ return n; }
                var p = .3;
                var s = p / 4;
                return Math.pow(2, -10 * n) * Math.sin((n - s) * (2 * Math.PI) / p) + 1;
        },

        elasticInOut: function(/* Decimal? */n){
                // summary:
                //              An easing function that elasticly snaps around the value, near
                //              the beginning and end of the Animation.
                // description:
                //              An easing function that elasticly snaps around the value, near
                //              the beginning and end of the Animation.
                //
                //              Use caution when the elasticity will cause values to become
                //              negative as some properties cannot be set to negative values.
                if(n == 0) return 0;
                n = n * 2;
                if(n == 2) return 1;
                var p = .3 * 1.5;
                var s = p / 4;
                if(n < 1){
                        n -= 1;
                        return -.5 * (Math.pow(2, 10 * n) * Math.sin((n - s) * (2 * Math.PI) / p));
                }
                n -= 1;
                return .5 * (Math.pow(2, -10 * n) * Math.sin((n - s) * (2 * Math.PI) / p)) + 1;
        },

        bounceIn: function(/* Decimal? */n){
                // summary:
                //              An easing function that 'bounces' near the beginning of an Animation
                return (1 - easingFuncs.bounceOut(1 - n)); // Decimal
        },

        bounceOut: function(/* Decimal? */n){
                // summary:
                //              An easing function that 'bounces' near the end of an Animation
                var s = 7.5625;
                var p = 2.75;
                var l;
                if(n < (1 / p)){
                        l = s * Math.pow(n, 2);
                }else if(n < (2 / p)){
                        n -= (1.5 / p);
                        l = s * Math.pow(n, 2) + .75;
                }else if(n < (2.5 / p)){
                        n -= (2.25 / p);
                        l = s * Math.pow(n, 2) + .9375;
                }else{
                        n -= (2.625 / p);
                        l = s * Math.pow(n, 2) + .984375;
                }
                return l;
        },

        bounceInOut: function(/* Decimal? */n){
                // summary:
                //              An easing function that 'bounces' at the beginning and end of the Animation
                if(n < 0.5){ return easingFuncs.bounceIn(n * 2) / 2; }
                return (easingFuncs.bounceOut(n * 2 - 1) / 2) + 0.5; // Decimal
        }
};

lang.setObject("dojo.fx.easing", easingFuncs);

return easingFuncs;
});