| /** |
| * @license |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * 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() { |
| 'use strict'; |
| |
| /** @extends Polymer.Element */ |
| class GrPageNav extends Polymer.GestureEventListeners( |
| Polymer.LegacyElementMixin( |
| Polymer.Element)) { |
| static get is() { return 'gr-page-nav'; } |
| |
| static get properties() { |
| return { |
| _headerHeight: Number, |
| }; |
| } |
| |
| /** @override */ |
| attached() { |
| super.attached(); |
| this.listen(window, 'scroll', '_handleBodyScroll'); |
| } |
| |
| /** @override */ |
| detached() { |
| super.detached(); |
| this.unlisten(window, 'scroll', '_handleBodyScroll'); |
| } |
| |
| _handleBodyScroll() { |
| if (this._headerHeight === undefined) { |
| let top = this._getOffsetTop(this); |
| for (let offsetParent = this.offsetParent; |
| offsetParent; |
| offsetParent = this._getOffsetParent(offsetParent)) { |
| top += this._getOffsetTop(offsetParent); |
| } |
| this._headerHeight = top; |
| } |
| |
| this.$.nav.classList.toggle('pinned', |
| this._getScrollY() >= this._headerHeight); |
| } |
| |
| /* Functions used for test purposes */ |
| _getOffsetParent(element) { |
| if (!element || !element.offsetParent) { return ''; } |
| return element.offsetParent; |
| } |
| |
| _getOffsetTop(element) { |
| return element.offsetTop; |
| } |
| |
| _getScrollY() { |
| return window.scrollY; |
| } |
| } |
| |
| customElements.define(GrPageNav.is, GrPageNav); |
| })(); |