4a89dfee3c
'element.offsetParent') which can be expereinced on a mobile Change-Id: Ibeea1ac11b6d4edce016f640c6204e255b30cc24
64 lines
1.8 KiB
JavaScript
64 lines
1.8 KiB
JavaScript
// Copyright (C) 2017 The Android Open Source Project
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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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(function() {
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'use strict';
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Polymer({
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is: 'gr-page-nav',
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properties: {
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_headerHeight: Number,
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},
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attached() {
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this.listen(window, 'scroll', '_handleBodyScroll');
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},
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detached() {
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this.unlisten(window, 'scroll', '_handleBodyScroll');
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},
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_handleBodyScroll() {
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if (this._headerHeight === undefined) {
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let top = this._getOffsetTop(this);
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// Don't want to include the element that wraps around the nav, start
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// with its parent.
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for (let offsetParent = this._getOffsetParent(this.offsetParent);
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offsetParent;
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offsetParent = this._getOffsetParent(offsetParent)) {
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top += this._getOffsetTop(offsetParent);
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}
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this._headerHeight = top;
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}
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this.$.nav.classList.toggle('pinned',
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this._getScrollY() >= this._headerHeight);
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},
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/* Functions used for test purposes */
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_getOffsetParent(element) {
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if (!element.offsetParent) { return ''; }
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return element.offsetParent;
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},
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_getOffsetTop(element) {
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return element.offsetTop;
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},
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_getScrollY() {
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return window.scrollY;
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},
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});
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})();
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