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/*
* Copyright (c) 2016-2023 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,
Subject,
bufferCount,
combineLatest,
distinctUntilChanged,
distinctUntilKeyChanged,
endWith,
finalize,
fromEvent,
ignoreElements,
map,
repeat,
skip,
takeUntil,
tap
} from "rxjs"
import { Viewport } from "~/browser"
import { Component } from "../_"
import { Header } from "../header"
import { Main } from "../main"
/* ----------------------------------------------------------------------------
* Types
* ------------------------------------------------------------------------- */
/**
* Back-to-top button
*/
export interface BackToTop {
hidden: boolean /* Back-to-top button is hidden */
}
/* ----------------------------------------------------------------------------
* Helper types
* ------------------------------------------------------------------------- */
/**
* Watch options
*/
interface WatchOptions {
viewport$: Observable<Viewport> /* Viewport observable */
main$: Observable<Main> /* Main area observable */
target$: Observable<HTMLElement> /* Location target observable */
}
/**
* Mount options
*/
interface MountOptions {
viewport$: Observable<Viewport> /* Viewport observable */
header$: Observable<Header> /* Header observable */
main$: Observable<Main> /* Main area observable */
target$: Observable<HTMLElement> /* Location target observable */
}
/* ----------------------------------------------------------------------------
* Functions
* ------------------------------------------------------------------------- */
/**
* Watch back-to-top
*
* @param _el - Back-to-top element
* @param options - Options
*
* @returns Back-to-top observable
*/
export function watchBackToTop(
_el: HTMLElement, { viewport$, main$, target$ }: WatchOptions
): Observable<BackToTop> {
/* Compute direction */
const direction$ = viewport$
.pipe(
map(({ offset: { y } }) => y),
bufferCount(2, 1),
map(([a, b]) => a > b && b > 0),
distinctUntilChanged()
)
/* Compute whether main area is active */
const active$ = main$
.pipe(
map(({ active }) => active)
)
/* Compute threshold for hiding */
return combineLatest([active$, direction$])
.pipe(
map(([active, direction]) => !(active && direction)),
distinctUntilChanged(),
takeUntil(target$.pipe(skip(1))),
endWith(true),
repeat({ delay: 250 }),
map(hidden => ({ hidden }))
)
}
/* ------------------------------------------------------------------------- */
/**
* Mount back-to-top
*
* @param el - Back-to-top element
* @param options - Options
*
* @returns Back-to-top component observable
*/
export function mountBackToTop(
el: HTMLElement, { viewport$, header$, main$, target$ }: MountOptions
): Observable<Component<BackToTop>> {
const push$ = new Subject<BackToTop>()
const done$ = push$.pipe(ignoreElements(), endWith(true))
push$.subscribe({
/* Handle emission */
next({ hidden }) {
el.hidden = hidden
if (hidden) {
el.setAttribute("tabindex", "-1")
el.blur()
} else {
el.removeAttribute("tabindex")
}
},
/* Handle complete */
complete() {
el.style.top = ""
el.hidden = true
el.removeAttribute("tabindex")
}
})
/* Watch header height */
header$
.pipe(
takeUntil(done$),
distinctUntilKeyChanged("height")
)
.subscribe(({ height }) => {
el.style.top = `${height + 16}px`
})
/* Go back to top */
fromEvent(el, "click")
.subscribe(ev => {
ev.preventDefault()
window.scrollTo({ top: 0 })
})
/* Create and return component */
return watchBackToTop(el, { viewport$, main$, target$ })
.pipe(
tap(state => push$.next(state)),
finalize(() => push$.complete()),
map(state => ({ ref: el, ...state }))
)
}
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