blob: 9a9dc0382f550a2bd65bf03a60b7f48c85587f93 [file] [log] [blame]
/**
* @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.
*/
import '../../../styles/shared-styles';
import {PolymerElement} from '@polymer/polymer/polymer-element';
import {htmlTemplate} from './gr-page-nav_html';
import {customElement, property} from '@polymer/decorators';
/**
* Augment the interface on top of PolymerElement
* for gr-page-nav.
*/
export interface GrPageNav {
$: {
// Note: this is needed to access $.nav
// with dotted property access
nav: HTMLElement;
};
}
@customElement('gr-page-nav')
export class GrPageNav extends PolymerElement {
static get template() {
return htmlTemplate;
}
@property({type: Number})
_headerHeight?: number;
private readonly bodyScrollHandler: () => void;
constructor() {
super();
this.bodyScrollHandler = () => this._handleBodyScroll();
}
connectedCallback() {
super.connectedCallback();
window.addEventListener('scroll', this.bodyScrollHandler);
}
disconnectedCallback() {
window.removeEventListener('scroll', this.bodyScrollHandler);
super.disconnectedCallback();
}
_handleBodyScroll() {
if (this._headerHeight === undefined) {
let top = this._getOffsetTop(this);
// TODO(TS): Element doesn't have offsetParent,
// while `offsetParent` are returning Element not HTMLElement
for (
let offsetParent = this.offsetParent as HTMLElement | undefined;
offsetParent;
offsetParent = this._getOffsetParent(offsetParent)
) {
top += this._getOffsetTop(offsetParent);
}
this._headerHeight = top;
}
this.$.nav.classList.toggle(
'pinned',
this._getScrollY() >= (this._headerHeight || 0)
);
}
/* Functions used for test purposes */
_getOffsetParent(element?: HTMLElement) {
if (!element || !('offsetParent' in element)) {
return undefined;
}
return element.offsetParent as HTMLElement;
}
_getOffsetTop(element: HTMLElement) {
return element.offsetTop;
}
_getScrollY() {
return window.scrollY;
}
}