biojs-vis-seqlogo/src/scroller/globals.js

A sequence logo visualizer

/** @license
 * Scroller
 * http://github.com/zynga/scroller
 *
 * Copyright 2011, Zynga Inc.
 * Licensed under the MIT License.
 * https://raw.github.com/zynga/scroller/master/MIT-LICENSE.txt
 *
 * Based on the work of: Unify Project (unify-project.org)
 * http://unify-project.org
 * Copyright 2011, Deutsche Telekom AG
 * License: MIT + Apache (V2)
 *
 * Inspired by: https://github.com/inexorabletash/raf-shim/blob/master/raf.js
 */
(function(global)
 {
   if(global.requestAnimationFrame) {
     return;
   }

   // Basic emulation of native methods for internal use

   var now = Date.now || function() {
     return +new Date;
   };

   var getKeys = Object.keys || function(obj) {

     var keys = {};
     for (var key in obj) {
       keys[key] = true;
     }

     return keys;

   };

   var isEmpty = Object.empty || function(obj) {

     for (var key in obj) {
       return false;
     }

     return true;

   };


   // requestAnimationFrame polyfill
   // http://webstuff.nfshost.com/anim-timing/Overview.html

   var postfix = "RequestAnimationFrame";
   var prefix = (function()
                 {
                   var all = "webkit,moz,o,ms".split(",");
                   for (var i=0; i<4; i++) {
                     if (global[all[i]+postfix] != null) {
                       return all[i];
                     }
                   }
                 })();

                 // Vendor specific implementation
                 if (prefix)
                   {
                     global.requestAnimationFrame = global[prefix+postfix];
                     global.cancelRequestAnimationFrame = global[prefix+"Cancel"+postfix];
                     return;
                   }

                   // Custom implementation
                   var TARGET_FPS = 60;
                   var requests = {};
                   var rafHandle = 1;
                   var timeoutHandle = null;

                   global.requestAnimationFrame = function(callback, root)
                   {
                     var callbackHandle = rafHandle++;

                     // Store callback
                     requests[callbackHandle] = callback;

                     // Create timeout at first request
                     if (timeoutHandle === null)
                       {
                         timeoutHandle = setTimeout(function()
                                                    {
                                                      var time = now();
                                                      var currentRequests = requests;
                                                      var keys = getKeys(currentRequests);

                                                      // Reset data structure before executing callbacks
                                                      requests = {};
                                                      timeoutHandle = null;

                                                      // Process all callbacks
                                                      for (var i=0, l=keys.length; i<l; i++) {
                                                        currentRequests[keys[i]](time);
                                                      }
                                                    }, 1000 / TARGET_FPS);
                       }

                       return callbackHandle;
                   };

                   global.cancelRequestAnimationFrame = function(handle)
                   {
                     delete requests[handle];

                     // Stop timeout if all where removed
                     if (isEmpty(requests))
                       {
                         clearTimeout(timeoutHandle);
                         timeoutHandle = null;
                       }
                   };

 })(this);