Files
mkdocs-material/src/assets/javascripts/components/header/offset/index.ts
2019-12-19 14:05:00 +01:00

112 lines
3.6 KiB
TypeScript

/*
* Copyright (c) 2016-2019 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 {
distinctUntilChanged,
map,
shareReplay,
switchMapTo
} from "rxjs/operators"
import { ViewportOffset, ViewportSize } from "../../../utilities"
import { Header } from "../_"
/* ----------------------------------------------------------------------------
* Helper types
* ------------------------------------------------------------------------- */
/**
* Options
*/
interface Options {
size$: Observable<ViewportSize> /* Viewport size observable */
offset$: Observable<ViewportOffset> /* Viewport offset observable */
header$: Observable<Header> /* Header observable */
}
/* ----------------------------------------------------------------------------
* Functions
* ------------------------------------------------------------------------- */
/**
* Watch viewport offset relative to an element's top
*
* This function returns an observable that computes the relative offset to the
* top of the given element based on the current viewport offset.
*
* @param el - HTML element
* @param options - Options
*
* @return Viewport offset observable
*/
export function watchHeaderOffsetToTopOf(
el: HTMLElement, { size$, offset$, header$ }: Options
): Observable<ViewportOffset> {
/* Compute necessary adjustment for offset */
const adjust$ = size$
.pipe(
switchMapTo(header$),
map(({ height }) => el.offsetTop - height),
distinctUntilChanged()
)
/* Compute relative offset and return as hot observable */
return combineLatest([offset$, adjust$])
.pipe(
map(([{ x, y }, adjust]) => ({ x, y: y - adjust })),
shareReplay(1)
)
}
/**
* Watch viewport offset relative to an element's bottom
*
* This function returns an observable that computes the relative offset to the
* bottom of the given element based on the current viewport offset.
*
* @param el - HTML element
* @param options - Options
*
* @return Viewport offset observable
*/
export function watchHeaderOffsetToBottomOf(
el: HTMLElement, { size$, offset$, header$ }: Options
): Observable<ViewportOffset> {
/* Compute necessary adjustment for offset */
const adjust$ = size$
.pipe(
switchMapTo(header$),
map(({ height }) => el.offsetTop + el.offsetHeight - height),
distinctUntilChanged()
)
/* Compute relative offset and return as hot observable */
return combineLatest([offset$, adjust$])
.pipe(
map(([{ x, y }, adjust]) => ({ x, y: y - adjust })),
shareReplay(1)
)
}