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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 { | |
| MonoTypeOperatorFunction, | |
| Observable, | |
| animationFrameScheduler, | |
| combineLatest, | |
| pipe | |
| } from "rxjs" | |
| import { | |
| distinctUntilChanged, | |
| distinctUntilKeyChanged, | |
| finalize, | |
| map, | |
| observeOn, | |
| switchMap, | |
| tap | |
| } from "rxjs/operators" | |
| import { Viewport, watchElementSize } from "browser" | |
| import { Header } from "../../header" | |
| import { Main } from "../_" | |
| import { | |
| resetHeaderShadow, | |
| setHeaderShadow | |
| } from "../set" | |
| /* ---------------------------------------------------------------------------- | |
| * Helper types | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Watch options | |
| */ | |
| interface WatchOptions { | |
| header$: Observable<Header> /* Header observable */ | |
| viewport$: Observable<Viewport> /* Viewport observable */ | |
| } | |
| /* ---------------------------------------------------------------------------- | |
| * Functions | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Watch main area | |
| * | |
| * This function returns an observable that computes the visual parameters of | |
| * the main area which depends on the viewport vertical offset and height, as | |
| * well as the height of the header element, if the header is fixed. | |
| * | |
| * @param el - Main area element | |
| * @param options - Options | |
| * | |
| * @return Main area observable | |
| */ | |
| export function watchMain( | |
| el: HTMLElement, { header$, viewport$ }: WatchOptions | |
| ): Observable<Main> { | |
| /* Compute necessary adjustment for header */ | |
| const adjust$ = header$ | |
| .pipe( | |
| map(({ height }) => height), | |
| distinctUntilChanged() | |
| ) | |
| /* Compute the main area's top and bottom borders */ | |
| const border$ = adjust$ | |
| .pipe( | |
| switchMap(() => watchElementSize(el) | |
| .pipe( | |
| map(({ height }) => ({ | |
| top: el.offsetTop, | |
| bottom: el.offsetTop + height | |
| })), | |
| distinctUntilKeyChanged("bottom") | |
| ) | |
| ) | |
| ) | |
| /* Compute the main area's offset, visible height and if we scrolled past */ | |
| return combineLatest([adjust$, border$, viewport$]) | |
| .pipe( | |
| map(([header, { top, bottom }, { offset: { y }, size: { height } }]) => { | |
| height = Math.max(0, height | |
| - Math.max(0, top - y, header) | |
| - Math.max(0, height + y - bottom) | |
| ) | |
| return { | |
| offset: top - header, | |
| height, | |
| active: top - header <= y | |
| } | |
| }), | |
| distinctUntilChanged<Main>((a, b) => { | |
| return a.offset === b.offset | |
| && a.height === b.height | |
| && a.active === b.active | |
| }) | |
| ) | |
| } | |
| /* ------------------------------------------------------------------------- */ | |
| /** | |
| * Apply header shadow | |
| * | |
| * @param el - Header element | |
| * | |
| * @return Operator function | |
| */ | |
| export function applyHeaderShadow( | |
| el: HTMLElement | |
| ): MonoTypeOperatorFunction<Main> { | |
| return pipe( | |
| /* Defer repaint to next animation frame */ | |
| observeOn(animationFrameScheduler), | |
| tap(({ active }) => { | |
| setHeaderShadow(el, active) | |
| }), | |
| /* Reset on complete or error */ | |
| finalize(() => { | |
| resetHeaderShadow(el) | |
| }) | |
| ) | |
| } |