1// Copyright 2016 Google Inc. All rights reserved. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15(function(shared) { 16 // If the polyfill is being loaded in a context where Element.animate is 17 // supported but object-form syntax is not, then creating an animation 18 // using the new syntax will either have no effect or will throw an exception. 19 // In either case, we want to proceed to load this part of the polyfill. 20 // 21 // The test animation uses an opacity other than the one the element already 22 // has, and doesn't need to change during the animation for the test to work. 23 // After the test, the element's opacity will be left how we found it: 24 // - If the animation is not created, the test will leave the element's 25 // opacity untouched at originalOpacity. 26 // - If the animation is created, it will be cancelled, and leave the 27 // element's opacity at originalOpacity. 28 // - If the animation is somehow created and runs without being cancelled, 29 // when it finishes after 1ms, it will cease to have any effect (because 30 // fill is not specified), and opacity will again be left at originalOpacity. 31 var element = document.documentElement; 32 var animation = null; 33 var animated = false; 34 try { 35 var originalOpacity = getComputedStyle(element).getPropertyValue('opacity'); 36 var testOpacity = originalOpacity == '0' ? '1' : '0'; 37 animation = element.animate({'opacity': [testOpacity, testOpacity]}, 38 {duration: 1}); 39 animation.currentTime = 0; 40 animated = getComputedStyle(element).getPropertyValue('opacity') == testOpacity; 41 } catch (error) { 42 } finally { 43 if (animation) 44 animation.cancel(); 45 } 46 if (animated) { 47 return; 48 } 49 50 var originalElementAnimate = window.Element.prototype.animate; 51 window.Element.prototype.animate = function(effectInput, options) { 52 if (window.Symbol && Symbol.iterator && Array.prototype.from && effectInput[Symbol.iterator]) { 53 // Handle custom iterables in most browsers by converting to an array 54 effectInput = Array.from(effectInput); 55 } 56 57 if (!Array.isArray(effectInput) && effectInput !== null) { 58 effectInput = shared.convertToArrayForm(effectInput); 59 } 60 61 return originalElementAnimate.call(this, effectInput, options); 62 }; 63})(webAnimationsShared); 64