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extract scroll code from renderer into hook

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Signed-off-by: Tilman Vatteroth <tilman.vatteroth@tu-dortmund.de>
This commit is contained in:
Tilman Vatteroth 2020-10-17 20:22:08 +02:00 committed by mrdrogdrog
parent 4603e3988a
commit 0750695e2f
3 changed files with 91 additions and 75 deletions
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82
src/components/editor/document-renderer-pane/scrolling-document-render-pane.tsx
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@ -1,7 +1,8 @@
import React, { useCallback, useEffect, useRef, useState } from 'react'
import React, { useMemo, useRef, useState } from 'react'
import { LineMarkerPosition } from '../../markdown-renderer/types'
import { ScrollProps, ScrollState } from '../scroll/scroll-props'
import { findLineMarks } from '../scroll/utils'
import { useScrollToLineMark } from '../scroll/hooks/use-scroll-to-line-mark'
import { useUserScroll } from '../scroll/hooks/use-user-scroll'
import { ScrollProps } from '../scroll/scroll-props'
import { DocumentRenderPane, DocumentRenderPaneProps } from './document-render-pane'
export const ScrollingDocumentRenderPane: React.FC<DocumentRenderPaneProps & ScrollProps> = ({
@ -14,81 +15,12 @@ export const ScrollingDocumentRenderPane: React.FC<DocumentRenderPaneProps & Scr
onScroll,
onTaskCheckedChange
}) => {
const lastScrollPosition = useRef<number>()
const renderer = useRef<HTMLDivElement>(null)
const [lineMarks, setLineMarks] = useState<LineMarkerPosition[]>()
const scrollTo = useCallback((targetPosition: number): void => {
if (!renderer.current || targetPosition === lastScrollPosition.current) {
return
}
lastScrollPosition.current = targetPosition
renderer.current.scrollTo({
top: targetPosition
})
}, [renderer])
useEffect(() => {
if (!renderer.current || !lineMarks || lineMarks.length === 0 || !scrollState) {
return
}
if (scrollState.firstLineInView < lineMarks[0].line) {
scrollTo(0)
return
}
if (scrollState.firstLineInView > lineMarks[lineMarks.length - 1].line) {
scrollTo(renderer.current.offsetHeight)
return
}
const { lastMarkBefore, firstMarkAfter } = findLineMarks(lineMarks, scrollState.firstLineInView)
const positionBefore = lastMarkBefore ? lastMarkBefore.position : lineMarks[0].position
const positionAfter = firstMarkAfter ? firstMarkAfter.position : renderer.current.offsetHeight
const lastMarkBeforeLine = lastMarkBefore ? lastMarkBefore.line : 1
const firstMarkAfterLine = firstMarkAfter ? firstMarkAfter.line : content.split('\n').length
const lineCount = firstMarkAfterLine - lastMarkBeforeLine
const blockHeight = positionAfter - positionBefore
const lineHeight = blockHeight / lineCount
const position = positionBefore + (scrollState.firstLineInView - lastMarkBeforeLine) * lineHeight + scrollState.scrolledPercentage / 100 * lineHeight
const correctedPosition = Math.floor(position)
scrollTo(correctedPosition)
}, [content, lineMarks, scrollState, scrollTo])
const userScroll = useCallback(() => {
if (!renderer.current || !lineMarks || lineMarks.length === 0 || !onScroll) {
return
}
const scrollTop = renderer.current.scrollTop
const lineMarksBeforeScrollTop = lineMarks.filter(lineMark => lineMark.position <= scrollTop)
if (lineMarksBeforeScrollTop.length === 0) {
return
}
const lineMarksAfterScrollTop = lineMarks.filter(lineMark => lineMark.position > scrollTop)
if (lineMarksAfterScrollTop.length === 0) {
return
}
const beforeLineMark = lineMarksBeforeScrollTop
.reduce((prevLineMark, currentLineMark) =>
prevLineMark.line >= currentLineMark.line ? prevLineMark : currentLineMark)
const afterLineMark = lineMarksAfterScrollTop
.reduce((prevLineMark, currentLineMark) =>
prevLineMark.line < currentLineMark.line ? prevLineMark : currentLineMark)
const componentHeight = afterLineMark.position - beforeLineMark.position
const distanceToBefore = scrollTop - beforeLineMark.position
const percentageRaw = (distanceToBefore / componentHeight)
const lineCount = afterLineMark.line - beforeLineMark.line
const line = Math.floor(lineCount * percentageRaw + beforeLineMark.line)
const lineHeight = componentHeight / lineCount
const innerScrolling = Math.floor((distanceToBefore % lineHeight) / lineHeight * 100)
const newScrollState: ScrollState = { firstLineInView: line, scrolledPercentage: innerScrolling }
onScroll(newScrollState)
}, [lineMarks, onScroll])
const contentLineCount = useMemo(() => content.split('\n').length, [content])
useScrollToLineMark(scrollState, lineMarks, contentLineCount, renderer)
const userScroll = useUserScroll(lineMarks, renderer, onScroll)
return (
<DocumentRenderPane

43
src/components/editor/scroll/hooks/use-scroll-to-line-mark.ts Normal file
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@ -0,0 +1,43 @@
import { RefObject, useCallback, useEffect, useRef } from 'react'
import { LineMarkerPosition } from '../../../markdown-renderer/types'
import { ScrollState } from '../scroll-props'
import { findLineMarks } from '../utils'
export const useScrollToLineMark = (scrollState: ScrollState | undefined, lineMarks: LineMarkerPosition[] | undefined, contentLineCount: number, renderer: RefObject<HTMLElement>): void => {
const lastScrollPosition = useRef<number>()
const scrollTo = useCallback((targetPosition: number): void => {
if (!renderer.current || targetPosition === lastScrollPosition.current) {
return
}
lastScrollPosition.current = targetPosition
renderer.current.scrollTo({
top: targetPosition
})
}, [renderer])
useEffect(() => {
if (!renderer.current || !lineMarks || lineMarks.length === 0 || !scrollState) {
return
}
if (scrollState.firstLineInView < lineMarks[0].line) {
scrollTo(0)
return
}
if (scrollState.firstLineInView > lineMarks[lineMarks.length - 1].line) {
scrollTo(renderer.current.offsetHeight)
return
}
const { lastMarkBefore, firstMarkAfter } = findLineMarks(lineMarks, scrollState.firstLineInView)
const positionBefore = lastMarkBefore ? lastMarkBefore.position : lineMarks[0].position
const positionAfter = firstMarkAfter ? firstMarkAfter.position : renderer.current.offsetHeight
const lastMarkBeforeLine = lastMarkBefore ? lastMarkBefore.line : 1
const firstMarkAfterLine = firstMarkAfter ? firstMarkAfter.line : contentLineCount
const linesBetweenMarkers = firstMarkAfterLine - lastMarkBeforeLine
const blockHeight = positionAfter - positionBefore
const lineHeight = blockHeight / linesBetweenMarkers
const position = positionBefore + (scrollState.firstLineInView - lastMarkBeforeLine) * lineHeight + scrollState.scrolledPercentage / 100 * lineHeight
const correctedPosition = Math.floor(position)
scrollTo(correctedPosition)
}, [contentLineCount, lineMarks, renderer, scrollState, scrollTo])
}

41
src/components/editor/scroll/hooks/use-user-scroll.ts Normal file
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@ -0,0 +1,41 @@
import { RefObject, useCallback } from 'react'
import { LineMarkerPosition } from '../../../markdown-renderer/types'
import { ScrollState } from '../scroll-props'
export const useUserScroll = (lineMarks: LineMarkerPosition[] | undefined, renderer: RefObject<HTMLElement>, onScroll: ((newScrollState: ScrollState) => void)|undefined): () => void =>
useCallback(() => {
if (!renderer.current || !lineMarks || lineMarks.length === 0 || !onScroll) {
return
}
const scrollTop = renderer.current.scrollTop
const lineMarksBeforeScrollTop = lineMarks.filter(lineMark => lineMark.position <= scrollTop)
if (lineMarksBeforeScrollTop.length === 0) {
return
}
const lineMarksAfterScrollTop = lineMarks.filter(lineMark => lineMark.position > scrollTop)
if (lineMarksAfterScrollTop.length === 0) {
return
}
const beforeLineMark = lineMarksBeforeScrollTop
.reduce((prevLineMark, currentLineMark) =>
prevLineMark.line >= currentLineMark.line ? prevLineMark : currentLineMark)
const afterLineMark = lineMarksAfterScrollTop
.reduce((prevLineMark, currentLineMark) =>
prevLineMark.line < currentLineMark.line ? prevLineMark : currentLineMark)
const componentHeight = afterLineMark.position - beforeLineMark.position
const distanceToBefore = scrollTop - beforeLineMark.position
const percentageRaw = (distanceToBefore / componentHeight)
const lineCount = afterLineMark.line - beforeLineMark.line
const line = Math.floor(lineCount * percentageRaw + beforeLineMark.line)
const lineHeight = componentHeight / lineCount
const innerScrolling = Math.floor((distanceToBefore % lineHeight) / lineHeight * 100)
const newScrollState: ScrollState = { firstLineInView: line, scrolledPercentage: innerScrolling }
onScroll(newScrollState)
}, [lineMarks, onScroll, renderer])