Function syncScrollToEdit

public/js/lib/syncscroll.js:278–351

(event, preventAnimate)

let viewScrollingTimer = null

export function syncScrollToEdit (event, preventAnimate) {
  if (appState.currentMode !== modeType.both || !appState.syncscroll || !editArea) return
  if (window.preventSyncScrollToEdit) {
    if (typeof window.preventSyncScrollToEdit === 'number') {
      window.preventSyncScrollToEdit--
    } else {
      window.preventSyncScrollToEdit = false
    }
    return
  }
  if (!scrollMap || !lineHeightMap) {
    buildMap(() => {
      syncScrollToEdit(event, preventAnimate)
    })
    return
  }
  if (editScrolling) return

  const scrollTop = viewArea[0].scrollTop
  let lineIndex = 0
  for (let i = 0, l = scrollMap.length; i < l; i++) {
    if (scrollMap[i] > scrollTop) {
      break
    } else {
      lineIndex = i
    }
  }
  let lineNo = 0
  let lineDiff = 0
  for (let i = 0, l = lineHeightMap.length; i < l; i++) {
    if (lineHeightMap[i] > lineIndex) {
      break
    } else {
      lineNo = lineHeightMap[i]
      lineDiff = lineHeightMap[i + 1] - lineNo
    }
  }

  let posTo = 0
  let topDiffPercent = 0
  let posToNextDiff = 0
  const scrollInfo = editor.getScrollInfo()
  const textHeight = editor.defaultTextHeight()
  const preLastLineHeight = scrollInfo.height - scrollInfo.clientHeight - textHeight
  const preLastLineNo = Math.round(preLastLineHeight / textHeight)
  const preLastLinePos = scrollMap[preLastLineNo]

  if (scrollInfo.height > scrollInfo.clientHeight && scrollTop >= preLastLinePos) {
    posTo = preLastLineHeight
    topDiffPercent = (scrollTop - preLastLinePos) / (viewBottom - preLastLinePos)
    posToNextDiff = textHeight * topDiffPercent
    posTo += Math.ceil(posToNextDiff)
  } else {
    posTo = lineNo * textHeight
    topDiffPercent = (scrollTop - scrollMap[lineNo]) / (scrollMap[lineNo + lineDiff] - scrollMap[lineNo])
    posToNextDiff = textHeight * lineDiff * topDiffPercent
    posTo += Math.ceil(posToNextDiff)
  }