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// Copyright 2016 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
(function(shared) {
// If the polyfill is being loaded in a context where Element.animate is
// supported but object-form syntax is not, then creating an animation
// using the new syntax will either have no effect or will throw an exception.
// In either case, we want to proceed to load this part of the polyfill.
//
// The test animation uses an opacity other than the one the element already
// has, and doesn't need to change during the animation for the test to work.
// After the test, the element's opacity will be left how we found it:
// - If the animation is not created, the test will leave the element's
// opacity untouched at originalOpacity.
// - If the animation is created, it will be cancelled, and leave the
// element's opacity at originalOpacity.
// - If the animation is somehow created and runs without being cancelled,
// when it finishes after 1ms, it will cease to have any effect (because
// fill is not specified), and opacity will again be left at originalOpacity.
var element = document.documentElement;
var animation = null;
var animated = false;
try {
var originalOpacity = getComputedStyle(element).getPropertyValue('opacity');
var testOpacity = originalOpacity == '0' ? '1' : '0';
animation = element.animate({'opacity': [testOpacity, testOpacity]},
{duration: 1});
animation.currentTime = 0;
animated = getComputedStyle(element).getPropertyValue('opacity') == testOpacity;
} catch (error) {
} finally {
if (animation)
animation.cancel();
}
if (animated) {
return;
}
var originalElementAnimate = window.Element.prototype.animate;
window.Element.prototype.animate = function(effectInput, options) {
if (window.Symbol && Symbol.iterator && Array.prototype.from && effectInput[Symbol.iterator]) {
// Handle custom iterables in most browsers by converting to an array
effectInput = Array.from(effectInput);
}
if (!Array.isArray(effectInput) && effectInput !== null) {
effectInput = shared.convertToArrayForm(effectInput);
}
return originalElementAnimate.call(this, effectInput, options);
};
})(webAnimationsShared);
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