mirror of
https://github.com/squidfunk/mkdocs-material.git
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118 lines
3.9 KiB
TypeScript
118 lines
3.9 KiB
TypeScript
/*
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* Copyright (c) 2016-2019 Martin Donath <martin.donath@squidfunk.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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import { Observable, combineLatest } from "rxjs"
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import {
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distinctUntilChanged,
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map,
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pluck,
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shareReplay
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} from "rxjs/operators"
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import { ViewportOffset, ViewportSize } from "../../utilities"
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import { Header } from "../header"
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/* ----------------------------------------------------------------------------
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* Types
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* ------------------------------------------------------------------------- */
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/**
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* Main area
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*/
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export interface Main {
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offset: number /* Main area top offset */
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height: number /* Main area visible height */
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active: boolean /* Scrolled past top offset */
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}
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/* ----------------------------------------------------------------------------
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* Function types
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* ------------------------------------------------------------------------- */
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/**
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* Options
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*/
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interface Options {
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size$: Observable<ViewportSize> /* Viewport size observable */
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offset$: Observable<ViewportOffset> /* Viewport offset observable */
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header$: Observable<Header> /* Header observable */
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}
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/* ----------------------------------------------------------------------------
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* Functions
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* ------------------------------------------------------------------------- */
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/**
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* Watch main area
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*
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* This function returns an observable that computes the visual parameters of
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* the main area from the viewport height and vertical offset, as well as the
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* height of the header element. The height of the main area is corrected by
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* the height of the header (if fixed) and footer element.
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*
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* @param el - Main area element
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* @param options - Options
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*
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* @return Main area observable
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*/
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export function watchMain(
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el: HTMLElement, { size$, offset$, header$ }: Options
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): Observable<Main> {
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/* Compute necessary adjustment for header */
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const adjust$ = header$
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.pipe(
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pluck("height")
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)
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/* Compute the main area's visible height */
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const height$ = combineLatest([offset$, size$, adjust$])
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.pipe(
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map(([{ y }, { height }, adjust]) => {
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const top = el.offsetTop
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const bottom = el.offsetHeight + top
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return height
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- Math.max(0, top - y, adjust)
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- Math.max(0, height + y - bottom)
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}),
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distinctUntilChanged()
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)
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/* Compute whether the viewport offset is past the main area's top */
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const active$ = combineLatest([offset$, adjust$])
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.pipe(
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map(([{ y }, adjust]) => y >= el.offsetTop - adjust),
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distinctUntilChanged()
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)
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/* Combine into a single hot observable */
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return combineLatest([height$, adjust$, active$])
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.pipe(
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map(([height, adjust, active]) => ({
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offset: el.offsetTop - adjust,
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height,
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active
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})),
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shareReplay(1)
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)
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}
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