84 lines
3.6 KiB
JavaScript
84 lines
3.6 KiB
JavaScript
// ==UserScript==
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// @name Adds scrolling JS that can be used within QB to do smarter scrolling
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// @qute-js-world jseval
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// @run-at document-start
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// ==/UserScript==
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unsafeWindow.scrollHelper = (() => {
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const scrollableElemOverflowTypes = [
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'auto',
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'scroll',
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]
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const getFocusedWindow = (nextElem) => {
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if (nextElem === null) return null
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if (nextElem === undefined) return getFocusedWindow(window.document.activeElement ?? null)
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return getFocusedWindow(nextElem.contentDocument?.activeElement ?? null) ?? nextElem.ownerDocument?.defaultView ?? null
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}
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const getScrollMaxY = ({ document: { documentElement } }) => documentElement.scrollHeight - documentElement.clientHeight
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const getWindowVisibleArea = ({ document: { documentElement } }) => documentElement.clientHeight * documentElement.clientWidth
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const findVertScrollableWindow = () => {
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const focusedWindow = getFocusedWindow() ?? window
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if (getScrollMaxY(focusedWindow) > 0) return focusedWindow
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if (getScrollMaxY(window) > 0) return window
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return Array
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.from(window.frames)
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.sort((x, y) => getWindowVisibleArea(y) - getWindowVisibleArea(x))
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.find((frame) => getScrollMaxY(frame) > 0) ?? window
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}
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const getScrollTopMax = (elem) => elem.scrollHeight - elem.clientHeight
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const isElementVertScrollable = (element) => element.clientHeight !==0 &&
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scrollableElemOverflowTypes.includes(getComputedStyle(element).overflowY)
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const findVertScrollableAncestor = (delta, nextElem) => {
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if (!(nextElem?.parentNode instanceof Element)) return nextElem
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if (isElementVertScrollable(nextElem)) {
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if (delta < 0 && nextElem.scrollTop > 0) return nextElem
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if (delta > 0 && nextElem.scrollTop < getScrollTopMax(nextElem)) return nextElem
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if (delta === 0 && getScrollTopMax(nextElem) > 0) return nextElem
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}
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return findVertScrollableAncestor(delta, nextElem.parentNode)
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}
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const getSelectionElem = () => {
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const selection = getFocusedWindow().getSelection()
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return selection.rangeCount !== 0
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? selection.getRangeAt(0).startContainer
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: null
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}
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const getParentIfNotElement = (maybeElement) => maybeElement instanceof Element ? maybeElement : maybeElement?.parentNode
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const findVertScrollable = (delta = 0) => {
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const selectionScrollableElem = findVertScrollableAncestor(delta, getParentIfNotElement(getSelectionElem()))
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if (selectionScrollableElem instanceof Element) return selectionScrollableElem
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const scrollableDoc = findVertScrollableWindow().document
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const scrollableElem = scrollableDoc.body || scrollableDoc.getElementsByTagName('body')[0] || scrollableDoc.documentElement
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return findVertScrollableAncestor(delta, getParentIfNotElement(scrollableElem))
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}
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return {
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scrollTo: (position) => findVertScrollable().scrollTo({top: position}),
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scrollToPercent: (percentPosition) => {
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const scrollElement = findVertScrollable()
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const paneHeight = scrollElement.scrollHeight
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scrollElement.scrollTo({top: percentPosition / 100 * paneHeight})
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},
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scrollBy: (delta) => findVertScrollable(delta).scrollBy({top: delta, behavior: 'smooth'}),
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scrollPage: (pages) => {
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const fakeDelta = pages < 0 ? -10 : 10
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const scrollElement = findVertScrollable(fakeDelta)
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const pageHeight = scrollElement.clientHeight
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scrollElement.scrollBy({top: pageHeight * pages})
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},
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}
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})()
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