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| /* | |
| * 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 { Observable, combineLatest } from "rxjs" | |
| import { | |
| distinctUntilKeyChanged, | |
| map, | |
| shareReplay | |
| } from "rxjs/operators" | |
| import { Header } from "components" | |
| import { | |
| ViewportOffset, | |
| watchViewportOffset | |
| } from "../offset" | |
| import { | |
| ViewportSize, | |
| watchViewportSize | |
| } from "../size" | |
| /* ---------------------------------------------------------------------------- | |
| * Types | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Viewport | |
| */ | |
| export interface Viewport { | |
| offset: ViewportOffset /* Viewport offset */ | |
| size: ViewportSize /* Viewport size */ | |
| } | |
| /* ---------------------------------------------------------------------------- | |
| * Helper types | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Watch at options | |
| */ | |
| interface WatchAtOptions { | |
| header$: Observable<Header> /* Header observable */ | |
| viewport$: Observable<Viewport> /* Viewport observable */ | |
| } | |
| /* ---------------------------------------------------------------------------- | |
| * Functions | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Watch viewport | |
| * | |
| * @return Viewport observable | |
| */ | |
| export function watchViewport(): Observable<Viewport> { | |
| return combineLatest([ | |
| watchViewportOffset(), | |
| watchViewportSize() | |
| ]) | |
| .pipe( | |
| map(([offset, size]) => ({ offset, size })), | |
| shareReplay({ bufferSize: 1, refCount: true }) | |
| ) | |
| } | |
| /** | |
| * Watch viewport relative to element | |
| * | |
| * @param el - Element | |
| * @param options - Options | |
| * | |
| * @return Viewport observable | |
| */ | |
| export function watchViewportAt( | |
| el: HTMLElement, { header$, viewport$ }: WatchAtOptions | |
| ): Observable<Viewport> { | |
| const size$ = viewport$ | |
| .pipe( | |
| distinctUntilKeyChanged("size") | |
| ) | |
| /* Compute element offset */ | |
| const offset$ = combineLatest([size$, header$]) | |
| .pipe( | |
| map((): ViewportOffset => ({ | |
| x: el.offsetLeft, | |
| y: el.offsetTop | |
| })) | |
| ) | |
| /* Compute relative viewport, return hot observable */ | |
| return combineLatest([header$, viewport$, offset$]) | |
| .pipe( | |
| map(([{ height }, { offset, size }, { x, y }]) => ({ | |
| offset: { | |
| x: offset.x - x, | |
| y: offset.y - y + height | |
| }, | |
| size | |
| })) | |
| ) | |
| } |