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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
}))
)
}