// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating

// requestAnimationFrame polyfill by Erik Möller. fixes from Paul Irish and Tino Zijdel

// MIT license

/**
 * A polyfill for requestAnimationFrame
 * You can actually use both requestAnimationFrame and requestAnimFrame,
 * you will still benefit from the polyfill
 *
 */

/**
 * A polyfill for cancelAnimationFrame
 *
 */
(function (window) {
    var lastTime = 0;
    var vendors = ['ms', 'moz', 'webkit', 'o'];

    for (var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
        window.requestAnimationFrame = window[vendors[x] + 'RequestAnimationFrame'];
        window.cancelAnimationFrame = window[vendors[x] + 'CancelAnimationFrame'] ||
            window[vendors[x] + 'CancelRequestAnimationFrame'];
    }

    if (!window.requestAnimationFrame) {
        window.requestAnimationFrame = function (callback) {
            var currTime = new Date().getTime();
            var timeToCall = Math.max(0, 16 - (currTime - lastTime));
            var id = window.setTimeout(function () { callback(currTime + timeToCall); },
              timeToCall);
            lastTime = currTime + timeToCall;
            return id;
        };
    }

    if (!window.cancelAnimationFrame) {
        window.cancelAnimationFrame = function (id) {
            clearTimeout(id);
        };
    }

    window.requestAnimFrame = window.requestAnimationFrame;
})(this);

/**
 * Converts a hex color number to an [R, G, B] array
 *
 * @param hex {number}
 */
function hex2rgb(hex) {
    return [(hex >> 16 & 0xFF) / 255, ( hex >> 8 & 0xFF) / 255, (hex & 0xFF)/ 255];
};

/**
 * Converts a color as an [R, G, B] array to a hex number
 *
 * @param rgb {Array}
 */
function rgb2hex(rgb) {
    return ((rgb[0]*255 << 16) + (rgb[1]*255 << 8) + rgb[2]*255);
};

/**
 * A polyfill for Function.prototype.bind
 *
 */
if (typeof Function.prototype.bind !== 'function') {
    Function.prototype.bind = (function () {
        return function (thisArg) {
            var target = this, i = arguments.length - 1, boundArgs = [];
            if (i > 0) {
                boundArgs.length = i;
                while (i--) boundArgs[i] = arguments[i + 1];
            }

            if (typeof target !== 'function') throw new TypeError();

            function bound() {
                var i = arguments.length, args = new Array(i);
                while (i--) args[i] = arguments[i];
                args = boundArgs.concat(args);
                return target.apply(this instanceof bound ? this : thisArg, args);
            }

            bound.prototype = (function F(proto) {
                if (proto) F.prototype = proto;
                if (!(this instanceof F)) return new F();
            })(target.prototype);

            return bound;
        };
    })();
}

/**
 * A wrapper for ajax requests to be handled cross browser
 *
 * @class
 * @namespace PIXI
 */
function AjaxRequest() {
    var activexmodes = ['Msxml2.XMLHTTP.6.0', 'Msxml2.XMLHTTP.3.0', 'Microsoft.XMLHTTP']; //activeX versions to check for in IE

    if (window.ActiveXObject) { //Test for support for ActiveXObject in IE first (as XMLHttpRequest in IE7 is broken)
        for (var i=0; i<activexmodes.length; i++) {
            try{
                return new window.ActiveXObject(activexmodes[i]);
            }
            catch(e) {
                //suppress error
            }
        }
    }
    else if (window.XMLHttpRequest) // if Mozilla, Safari etc
    {
        return new window.XMLHttpRequest();
    }
    else {
        return false;
    }
};
/*
function packColorRGBA(r, g, b, a)//r, g, b, a) {
  //  console.log(r, b, c, d)
  return (Math.floor((r)*63) << 18) | (Math.floor((g)*63) << 12) | (Math.floor((b)*63) << 6);// | (Math.floor((a)*63))
  //  i = i | (Math.floor((a)*63));
   // return i;
   // var r = (i / 262144.0 ) / 64;
   // var g = (i / 4096.0)%64 / 64;
  //  var b = (i / 64.0)%64 / 64;
  //  var a = (i)%64 / 64;

  //  console.log(r, g, b, a);
  //  return i;

};
 */
/*
function packColorRGB(r, g, b)//r, g, b, a) {
    return (Math.floor((r)*255) << 16) | (Math.floor((g)*255) << 8) | (Math.floor((b)*255));
};

function unpackColorRGB(r, g, b)//r, g, b, a) {
    return (Math.floor((r)*255) << 16) | (Math.floor((g)*255) << 8) | (Math.floor((b)*255));
};
 */

/**
 * Checks whether the Canvas BlendModes are supported by the current browser
 *
 * @return {boolean} whether they are supported
 */
function canUseNewCanvasBlendModes() {
    if (typeof document === 'undefined') return false;
    var canvas = document.createElement('canvas');
    canvas.width = 1;
    canvas.height = 1;
    var context = canvas.getContext('2d');
    context.fillStyle = '#000';
    context.fillRect(0,0,1,1);
    context.globalCompositeOperation = 'multiply';
    context.fillStyle = '#fff';
    context.fillRect(0,0,1,1);
    return context.getImageData(0,0,1,1).data[0] === 0;
};

/**
 * Given a number, this function returns the closest number that is a power of two
 * this function is taken from Starling Framework as its pretty neat ;)
 *
 * @param number {number}
 * @return {number} the closest number that is a power of two
 */
function getNextPowerOfTwo(number) {
    if (number > 0 && (number & (number - 1)) === 0) // see: http://goo.gl/D9kPj
        return number;
    else {
        var result = 1;
        while (result < number) result <<= 1;
        return result;
    }
};

/**
 * checks if the given width and height make a power of two texture
 * @param width {number}
 * @param height {number}
 * @return {boolean}
 */
function isPowerOfTwo(width, height) {
    return (width > 0 && (width & (width - 1)) === 0 && height > 0 && (height & (height - 1)) === 0);

};