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// Copyright 2014 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview A polyfill for window.requestAnimationFrame and
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 * window.cancelAnimationFrame.
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 * Code based on https://gist.github.com/paulirish/1579671
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 */
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goog.provide('goog.dom.animationFrame.polyfill');
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/**
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 * @define {boolean} If true, will install the requestAnimationFrame polyfill.
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 */
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goog.define('goog.dom.animationFrame.polyfill.ENABLED', true);
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/**
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 * Installs the requestAnimationFrame (and cancelAnimationFrame) polyfill.
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 */
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goog.dom.animationFrame.polyfill.install = function() {
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  if (goog.dom.animationFrame.polyfill.ENABLED) {
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    var vendors = ['ms', 'moz', 'webkit', 'o'];
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    for (var i = 0, v; v = vendors[i] && !goog.global.requestAnimationFrame;
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         ++i) {
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      goog.global.requestAnimationFrame =
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          goog.global[v + 'RequestAnimationFrame'];
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      goog.global.cancelAnimationFrame =
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          goog.global[v + 'CancelAnimationFrame'] ||
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          goog.global[v + 'CancelRequestAnimationFrame'];
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    }
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    if (!goog.global.requestAnimationFrame) {
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      var lastTime = 0;
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      goog.global.requestAnimationFrame = function(callback) {
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        var currTime = new Date().getTime();
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        var timeToCall = Math.max(0, 16 - (currTime - lastTime));
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        lastTime = currTime + timeToCall;
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        return goog.global.setTimeout(function() {
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          callback(currTime + timeToCall);
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        }, timeToCall);
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      };
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      if (!goog.global.cancelAnimationFrame) {
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        goog.global.cancelAnimationFrame = function(id) { clearTimeout(id); };
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      }
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    }
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  }
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};
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