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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,
fromEvent,
map,
merge,
startWith
} from "rxjs"
/* ----------------------------------------------------------------------------
* Types
* ------------------------------------------------------------------------- */
/**
* Viewport offset
*/
export interface ViewportOffset {
x: number /* Horizontal offset */
y: number /* Vertical offset */
}
/* ----------------------------------------------------------------------------
* Functions
* ------------------------------------------------------------------------- */
/**
* Retrieve viewport offset
*
* On iOS Safari, viewport offset can be negative due to overflow scrolling.
* As this may induce strange behaviors downstream, we'll just limit it to 0.
*
* @returns Viewport offset
*/
export function getViewportOffset(): ViewportOffset {
return {
x: Math.max(0, scrollX),
y: Math.max(0, scrollY)
}
}
/* ------------------------------------------------------------------------- */
/**
* Watch viewport offset
*
* @returns Viewport offset observable
*/
export function watchViewportOffset(): Observable<ViewportOffset> {
return merge(
fromEvent(window, "scroll", { passive: true }),
fromEvent(window, "resize", { passive: true })
)
.pipe(
map(getViewportOffset),
startWith(getViewportOffset())
)
}
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