101 lines
2.7 KiB
TypeScript
101 lines
2.7 KiB
TypeScript
/**
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* @license
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* 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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*/
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import '../../../styles/shared-styles';
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import {GestureEventListeners} from '@polymer/polymer/lib/mixins/gesture-event-listeners';
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import {LegacyElementMixin} from '@polymer/polymer/lib/legacy/legacy-element-mixin';
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import {PolymerElement} from '@polymer/polymer/polymer-element';
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import {htmlTemplate} from './gr-page-nav_html';
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import {customElement, property} from '@polymer/decorators';
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/**
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* Augment the interface on top of PolymerElement
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* for gr-page-nav.
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*/
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export interface GrPageNav {
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$: {
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// Note: this is needed to access $.nav
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// with dotted property access
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nav: HTMLElement;
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};
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}
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@customElement('gr-page-nav')
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export class GrPageNav extends GestureEventListeners(
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LegacyElementMixin(PolymerElement)
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) {
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static get template() {
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return htmlTemplate;
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}
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@property({type: Number})
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_headerHeight?: number;
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private readonly bodyScrollHandler: () => void;
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constructor() {
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super();
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this.bodyScrollHandler = () => this._handleBodyScroll();
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}
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attached() {
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super.attached();
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window.addEventListener('scroll', this.bodyScrollHandler);
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}
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detached() {
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super.detached();
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window.removeEventListener('scroll', this.bodyScrollHandler);
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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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// TODO(TS): Element doesn't have offsetParent,
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// while `offsetParent` are returning Element not HTMLElement
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for (
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let offsetParent = this.offsetParent as HTMLElement | undefined;
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offsetParent;
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offsetParent = this._getOffsetParent(offsetParent)
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) {
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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(
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'pinned',
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this._getScrollY() >= (this._headerHeight || 0)
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);
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}
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/* Functions used for test purposes */
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_getOffsetParent(element?: HTMLElement) {
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if (!element || !('offsetParent' in element)) {
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return undefined;
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}
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return element.offsetParent as HTMLElement;
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}
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_getOffsetTop(element: HTMLElement) {
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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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