Permalink
Cannot retrieve contributors at this time
| /* | |
| * Copyright (c) 2016-2020 Martin Donath <martin.donath@squidfunk.com> | |
| * | |
| * Permission is hereby granted, free of charge, to any person obtaining a copy | |
| * of this software and associated documentation files (the "Software"), to | |
| * deal in the Software without restriction, including without limitation the | |
| * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or | |
| * sell copies of the Software, and to permit persons to whom the Software is | |
| * furnished to do so, subject to the following conditions: | |
| * | |
| * The above copyright notice and this permission notice shall be included in | |
| * all copies or substantial portions of the Software. | |
| * | |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE | |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
| * IN THE SOFTWARE. | |
| */ | |
| import ResizeObserver from "resize-observer-polyfill" | |
| import { | |
| NEVER, | |
| Observable, | |
| Subject, | |
| defer, | |
| merge, | |
| of | |
| } from "rxjs" | |
| import { | |
| filter, | |
| finalize, | |
| map, | |
| shareReplay, | |
| startWith, | |
| switchMap, | |
| tap | |
| } from "rxjs/operators" | |
| /* ---------------------------------------------------------------------------- | |
| * Types | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Element offset | |
| */ | |
| export interface ElementSize { | |
| width: number /* Element width */ | |
| height: number /* Element height */ | |
| } | |
| /* ---------------------------------------------------------------------------- | |
| * Data | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Resize observer entry subject | |
| */ | |
| const entry$ = new Subject<ResizeObserverEntry>() | |
| /** | |
| * Resize observer observable | |
| * | |
| * This observable will create a `ResizeObserver` on the first subscription | |
| * and will automatically terminate it when there are no more subscribers. | |
| * It's quite important to centralize observation in a single `ResizeObserver`, | |
| * as the performance difference can be quite dramatic, as the link shows. | |
| * | |
| * @see https://bit.ly/3iIYfEm - Google Groups on performance | |
| */ | |
| const observer$ = defer(() => of( | |
| new ResizeObserver(entries => { | |
| for (const entry of entries) | |
| entry$.next(entry) | |
| }) | |
| )) | |
| .pipe( | |
| switchMap(resize => merge(of(resize), NEVER) | |
| .pipe( | |
| finalize(() => resize.disconnect()) | |
| ) | |
| ), | |
| shareReplay({ bufferSize: 1, refCount: true }) | |
| ) | |
| /* ---------------------------------------------------------------------------- | |
| * Functions | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Retrieve element size | |
| * | |
| * @param el - Element | |
| * | |
| * @return Element size | |
| */ | |
| export function getElementSize(el: HTMLElement): ElementSize { | |
| return { | |
| width: el.offsetWidth, | |
| height: el.offsetHeight | |
| } | |
| } | |
| /* ------------------------------------------------------------------------- */ | |
| /** | |
| * Watch element size | |
| * | |
| * This function returns an observable that will subscribe to a single internal | |
| * instance of `ResizeObserver` upon subscription, and emit resize events until | |
| * termination. Note that this function should not be called with the same | |
| * element twice, as the first unsubscription will terminate observation. | |
| * | |
| * @param el - Element | |
| * | |
| * @return Element size observable | |
| */ | |
| export function watchElementSize( | |
| el: HTMLElement | |
| ): Observable<ElementSize> { | |
| return observer$ | |
| .pipe( | |
| tap(observer => observer.observe(el)), | |
| switchMap(observer => entry$ | |
| .pipe( | |
| filter(({ target }) => target === el), | |
| finalize(() => observer.unobserve(el)), | |
| map(({ contentRect }) => ({ | |
| width: contentRect.width, | |
| height: contentRect.height | |
| })) | |
| ) | |
| ), | |
| startWith(getElementSize(el)) | |
| ) | |
| } |