requestNextAnimationFrame.js

/*
 * Copyright (C) 2012 David Geary. This code is from the book
 * Core HTML5 Canvas, published by Prentice-Hall in 2012.
 *
 * License:
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * The Software may not be used to create training material of any sort,
 * including courses, books, instructional videos, presentations, etc.
 * without the express written consent of David Geary.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
*/

window.requestNextAnimationFrame =
   (function () {
      var originalWebkitRequestAnimationFrame = undefined,
          wrapper = undefined,
          callback = undefined,
          geckoVersion = 0,
          userAgent = navigator.userAgent,
          index = 0,
          self = this;

      // Workaround for Chrome 10 bug where Chrome
      // does not pass the time to the animation function

      if (window.webkitRequestAnimationFrame) {
         // Define the wrapper

         wrapper = function (time) {
           if (time === undefined) {
              time = +new Date();
           }
           self.callback(time);
         };

         // Make the switch

         originalWebkitRequestAnimationFrame = window.webkitRequestAnimationFrame;

         window.webkitRequestAnimationFrame = function (callback, element) {
            self.callback = callback;

            // Browser calls the wrapper and wrapper calls the callback

            originalWebkitRequestAnimationFrame(wrapper, element);
         }
      }

      // Workaround for Gecko 2.0, which has a bug in
      // mozRequestAnimationFrame() that restricts animations
      // to 30-40 fps.

      if (window.mozRequestAnimationFrame) {
         // Check the Gecko version. Gecko is used by browsers
         // other than Firefox. Gecko 2.0 corresponds to
         // Firefox 4.0.

         index = userAgent.indexOf('rv:');

         if (userAgent.indexOf('Gecko') != -1) {
            geckoVersion = userAgent.substr(index + 3, 3);

            if (geckoVersion === '2.0') {
               // Forces the return statement to fall through
               // to the setTimeout() function.

               window.mozRequestAnimationFrame = undefined;
            }
         }
      }

      return window.requestAnimationFrame   ||
         window.webkitRequestAnimationFrame ||
         window.mozRequestAnimationFrame    ||
         window.oRequestAnimationFrame      ||
         window.msRequestAnimationFrame     ||

         function (callback, element) {
            var start,
                finish;

            window.setTimeout( function () {
               start = +new Date();
               callback(start);
               finish = +new Date();

               self.timeout = 1000 / 60 - (finish - start);

            }, self.timeout);
         };
      }
   )
();

/**
 * use: window.requestNextAnimationFrame(animate);
 */