From 0e9afde5fa87d7039d4cebd43e5613541c56849a Mon Sep 17 00:00:00 2001
From: Yukai Huang
Date: Tue, 11 Apr 2017 21:33:54 +0800
Subject: Move syncsroll under lib

---
 public/js/index.js          |   2 +-
 public/js/lib/syncscroll.js | 368 ++++++++++++++++++++++++++++++++++++++++++++
 public/js/syncscroll.js     | 368 --------------------------------------------
 3 files changed, 369 insertions(+), 369 deletions(-)
 create mode 100644 public/js/lib/syncscroll.js
 delete mode 100644 public/js/syncscroll.js

diff --git a/public/js/index.js b/public/js/index.js
index 0ca6827b..245cf299 100644
--- a/public/js/index.js
+++ b/public/js/index.js
@@ -65,7 +65,7 @@ import {
     setupSyncAreas,
     syncScrollToEdit,
     syncScrollToView
-} from './syncscroll'
+} from './lib/syncscroll'
 
 import {
     writeHistory,
diff --git a/public/js/lib/syncscroll.js b/public/js/lib/syncscroll.js
new file mode 100644
index 00000000..6b07e79c
--- /dev/null
+++ b/public/js/lib/syncscroll.js
@@ -0,0 +1,368 @@
+/* eslint-env browser, jquery */
+/* global _ */
+// Inject line numbers for sync scroll.
+
+import markdownitContainer from 'markdown-it-container'
+
+import { md } from '../extra'
+import modeType from '../lib/editor/modeType'
+
+function addPart (tokens, idx) {
+  if (tokens[idx].map && tokens[idx].level === 0) {
+    const startline = tokens[idx].map[0] + 1
+    const endline = tokens[idx].map[1]
+    tokens[idx].attrJoin('class', 'part')
+    tokens[idx].attrJoin('data-startline', startline)
+    tokens[idx].attrJoin('data-endline', endline)
+  }
+}
+
+md.renderer.rules.blockquote_open = function (tokens, idx, options, env, self) {
+  tokens[idx].attrJoin('class', 'raw')
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.table_open = function (tokens, idx, options, env, self) {
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.bullet_list_open = function (tokens, idx, options, env, self) {
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.list_item_open = function (tokens, idx, options, env, self) {
+  tokens[idx].attrJoin('class', 'raw')
+  if (tokens[idx].map) {
+    const startline = tokens[idx].map[0] + 1
+    const endline = tokens[idx].map[1]
+    tokens[idx].attrJoin('data-startline', startline)
+    tokens[idx].attrJoin('data-endline', endline)
+  }
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.ordered_list_open = function (tokens, idx, options, env, self) {
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.link_open = function (tokens, idx, options, env, self) {
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.paragraph_open = function (tokens, idx, options, env, self) {
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.heading_open = function (tokens, idx, options, env, self) {
+  tokens[idx].attrJoin('class', 'raw')
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+md.renderer.rules.fence = (tokens, idx, options, env, self) => {
+  const token = tokens[idx]
+  const info = token.info ? md.utils.unescapeAll(token.info).trim() : ''
+  let langName = ''
+  let highlighted
+
+  if (info) {
+    langName = info.split(/\s+/g)[0]
+    if (/!$/.test(info)) token.attrJoin('class', 'wrap')
+    token.attrJoin('class', options.langPrefix + langName.replace(/=$|=\d+$|=\+$|!$|=!/, ''))
+    token.attrJoin('class', 'hljs')
+    token.attrJoin('class', 'raw')
+  }
+
+  if (options.highlight) {
+    highlighted = options.highlight(token.content, langName) || md.utils.escapeHtml(token.content)
+  } else {
+    highlighted = md.utils.escapeHtml(token.content)
+  }
+
+  if (highlighted.indexOf('<pre') === 0) {
+    return `${highlighted}\n`
+  }
+
+  if (tokens[idx].map && tokens[idx].level === 0) {
+    const startline = tokens[idx].map[0] + 1
+    const endline = tokens[idx].map[1]
+    return `<pre class="part" data-startline="${startline}" data-endline="${endline}"><code${self.renderAttrs(token)}>${highlighted}</code></pre>\n`
+  }
+
+  return `<pre><code${self.renderAttrs(token)}>${highlighted}</code></pre>\n`
+}
+md.renderer.rules.code_block = (tokens, idx, options, env, self) => {
+  if (tokens[idx].map && tokens[idx].level === 0) {
+    const startline = tokens[idx].map[0] + 1
+    const endline = tokens[idx].map[1]
+    return `<pre class="part" data-startline="${startline}" data-endline="${endline}"><code>${md.utils.escapeHtml(tokens[idx].content)}</code></pre>\n`
+  }
+  return `<pre><code>${md.utils.escapeHtml(tokens[idx].content)}</code></pre>\n`
+}
+function renderContainer (tokens, idx, options, env, self) {
+  tokens[idx].attrJoin('role', 'alert')
+  tokens[idx].attrJoin('class', 'alert')
+  tokens[idx].attrJoin('class', `alert-${tokens[idx].info.trim()}`)
+  addPart(tokens, idx)
+  return self.renderToken(...arguments)
+}
+
+md.use(markdownitContainer, 'success', { render: renderContainer })
+md.use(markdownitContainer, 'info', { render: renderContainer })
+md.use(markdownitContainer, 'warning', { render: renderContainer })
+md.use(markdownitContainer, 'danger', { render: renderContainer })
+
+// FIXME: expose syncscroll to window
+window.syncscroll = true
+
+window.preventSyncScrollToEdit = false
+window.preventSyncScrollToView = false
+
+const editScrollThrottle = 5
+const viewScrollThrottle = 5
+const buildMapThrottle = 100
+
+let viewScrolling = false
+let editScrolling = false
+
+let editArea = null
+let viewArea = null
+let markdownArea = null
+
+export function setupSyncAreas (edit, view, markdown) {
+  editArea = edit
+  viewArea = view
+  markdownArea = markdown
+  editArea.on('scroll', _.throttle(syncScrollToView, editScrollThrottle))
+  viewArea.on('scroll', _.throttle(syncScrollToEdit, viewScrollThrottle))
+}
+
+let scrollMap, lineHeightMap, viewTop, viewBottom
+
+export function clearMap () {
+  scrollMap = null
+  lineHeightMap = null
+  viewTop = null
+  viewBottom = null
+}
+window.viewAjaxCallback = clearMap
+
+const buildMap = _.throttle(buildMapInner, buildMapThrottle)
+
+// Build offsets for each line (lines can be wrapped)
+// That's a bit dirty to process each line everytime, but ok for demo.
+// Optimizations are required only for big texts.
+function buildMapInner (callback) {
+  if (!viewArea || !markdownArea) return
+  let i, offset, nonEmptyList, pos, a, b, _lineHeightMap, linesCount, acc, _scrollMap
+
+  offset = viewArea.scrollTop() - viewArea.offset().top
+  _scrollMap = []
+  nonEmptyList = []
+  _lineHeightMap = []
+  viewTop = 0
+  viewBottom = viewArea[0].scrollHeight - viewArea.height()
+
+  acc = 0
+  const lines = window.editor.getValue().split('\n')
+  const lineHeight = window.editor.defaultTextHeight()
+  for (i = 0; i < lines.length; i++) {
+    const str = lines[i]
+
+    _lineHeightMap.push(acc)
+
+    if (str.length === 0) {
+      acc++
+      continue
+    }
+
+    const h = window.editor.heightAtLine(i + 1) - window.editor.heightAtLine(i)
+    acc += Math.round(h / lineHeight)
+  }
+  _lineHeightMap.push(acc)
+  linesCount = acc
+
+  for (i = 0; i < linesCount; i++) {
+    _scrollMap.push(-1)
+  }
+
+  nonEmptyList.push(0)
+    // make the first line go top
+  _scrollMap[0] = viewTop
+
+  const parts = markdownArea.find('.part').toArray()
+  for (i = 0; i < parts.length; i++) {
+    const $el = $(parts[i])
+    let t = $el.attr('data-startline') - 1
+    if (t === '') {
+      return
+    }
+    t = _lineHeightMap[t]
+    if (t !== 0 && t !== nonEmptyList[nonEmptyList.length - 1]) {
+      nonEmptyList.push(t)
+    }
+    _scrollMap[t] = Math.round($el.offset().top + offset - 10)
+  }
+
+  nonEmptyList.push(linesCount)
+  _scrollMap[linesCount] = viewArea[0].scrollHeight
+
+  pos = 0
+  for (i = 1; i < linesCount; i++) {
+    if (_scrollMap[i] !== -1) {
+      pos++
+      continue
+    }
+
+    a = nonEmptyList[pos]
+    b = nonEmptyList[pos + 1]
+    _scrollMap[i] = Math.round((_scrollMap[b] * (i - a) + _scrollMap[a] * (b - i)) / (b - a))
+  }
+
+  _scrollMap[0] = 0
+
+  scrollMap = _scrollMap
+  lineHeightMap = _lineHeightMap
+
+  if (window.loaded && callback) callback()
+}
+
+// sync view scroll progress to edit
+let viewScrollingTimer = null
+
+export function syncScrollToEdit (event, preventAnimate) {
+  if (window.currentMode !== modeType.both || !window.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 = window.editor.getScrollInfo()
+  const textHeight = window.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)
+  }
+
+  if (preventAnimate) {
+    editArea.scrollTop(posTo)
+  } else {
+    const posDiff = Math.abs(scrollInfo.top - posTo)
+    var duration = posDiff / 50
+    duration = duration >= 100 ? duration : 100
+    editArea.stop(true, true).animate({
+      scrollTop: posTo
+    }, duration, 'linear')
+  }
+
+  viewScrolling = true
+  clearTimeout(viewScrollingTimer)
+  viewScrollingTimer = setTimeout(viewScrollingTimeoutInner, duration * 1.5)
+}
+
+function viewScrollingTimeoutInner () {
+  viewScrolling = false
+}
+
+// sync edit scroll progress to view
+let editScrollingTimer = null
+
+export function syncScrollToView (event, preventAnimate) {
+  if (window.currentMode !== modeType.both || !window.syncscroll || !viewArea) return
+  if (window.preventSyncScrollToView) {
+    if (typeof preventSyncScrollToView === 'number') {
+      window.preventSyncScrollToView--
+    } else {
+      window.preventSyncScrollToView = false
+    }
+    return
+  }
+  if (!scrollMap || !lineHeightMap) {
+    buildMap(() => {
+      syncScrollToView(event, preventAnimate)
+    })
+    return
+  }
+  if (viewScrolling) return
+
+  let lineNo, posTo
+  let topDiffPercent, posToNextDiff
+  const scrollInfo = window.editor.getScrollInfo()
+  const textHeight = window.editor.defaultTextHeight()
+  lineNo = Math.floor(scrollInfo.top / textHeight)
+    // if reach the last line, will start lerp to the bottom
+  const diffToBottom = (scrollInfo.top + scrollInfo.clientHeight) - (scrollInfo.height - textHeight)
+  if (scrollInfo.height > scrollInfo.clientHeight && diffToBottom > 0) {
+    topDiffPercent = diffToBottom / textHeight
+    posTo = scrollMap[lineNo + 1]
+    posToNextDiff = (viewBottom - posTo) * topDiffPercent
+    posTo += Math.floor(posToNextDiff)
+  } else {
+    topDiffPercent = (scrollInfo.top % textHeight) / textHeight
+    posTo = scrollMap[lineNo]
+    posToNextDiff = (scrollMap[lineNo + 1] - posTo) * topDiffPercent
+    posTo += Math.floor(posToNextDiff)
+  }
+
+  if (preventAnimate) {
+    viewArea.scrollTop(posTo)
+  } else {
+    const posDiff = Math.abs(viewArea.scrollTop() - posTo)
+    var duration = posDiff / 50
+    duration = duration >= 100 ? duration : 100
+    viewArea.stop(true, true).animate({
+      scrollTop: posTo
+    }, duration, 'linear')
+  }
+
+  editScrolling = true
+  clearTimeout(editScrollingTimer)
+  editScrollingTimer = setTimeout(editScrollingTimeoutInner, duration * 1.5)
+}
+
+function editScrollingTimeoutInner () {
+  editScrolling = false
+}
diff --git a/public/js/syncscroll.js b/public/js/syncscroll.js
deleted file mode 100644
index ad21e57b..00000000
--- a/public/js/syncscroll.js
+++ /dev/null
@@ -1,368 +0,0 @@
-/* eslint-env browser, jquery */
-/* global _ */
-// Inject line numbers for sync scroll.
-
-import markdownitContainer from 'markdown-it-container'
-
-import { md } from './extra'
-import modeType from './lib/editor/modeType'
-
-function addPart (tokens, idx) {
-  if (tokens[idx].map && tokens[idx].level === 0) {
-    const startline = tokens[idx].map[0] + 1
-    const endline = tokens[idx].map[1]
-    tokens[idx].attrJoin('class', 'part')
-    tokens[idx].attrJoin('data-startline', startline)
-    tokens[idx].attrJoin('data-endline', endline)
-  }
-}
-
-md.renderer.rules.blockquote_open = function (tokens, idx, options, env, self) {
-  tokens[idx].attrJoin('class', 'raw')
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.table_open = function (tokens, idx, options, env, self) {
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.bullet_list_open = function (tokens, idx, options, env, self) {
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.list_item_open = function (tokens, idx, options, env, self) {
-  tokens[idx].attrJoin('class', 'raw')
-  if (tokens[idx].map) {
-    const startline = tokens[idx].map[0] + 1
-    const endline = tokens[idx].map[1]
-    tokens[idx].attrJoin('data-startline', startline)
-    tokens[idx].attrJoin('data-endline', endline)
-  }
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.ordered_list_open = function (tokens, idx, options, env, self) {
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.link_open = function (tokens, idx, options, env, self) {
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.paragraph_open = function (tokens, idx, options, env, self) {
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.heading_open = function (tokens, idx, options, env, self) {
-  tokens[idx].attrJoin('class', 'raw')
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-md.renderer.rules.fence = (tokens, idx, options, env, self) => {
-  const token = tokens[idx]
-  const info = token.info ? md.utils.unescapeAll(token.info).trim() : ''
-  let langName = ''
-  let highlighted
-
-  if (info) {
-    langName = info.split(/\s+/g)[0]
-    if (/!$/.test(info)) token.attrJoin('class', 'wrap')
-    token.attrJoin('class', options.langPrefix + langName.replace(/=$|=\d+$|=\+$|!$|=!/, ''))
-    token.attrJoin('class', 'hljs')
-    token.attrJoin('class', 'raw')
-  }
-
-  if (options.highlight) {
-    highlighted = options.highlight(token.content, langName) || md.utils.escapeHtml(token.content)
-  } else {
-    highlighted = md.utils.escapeHtml(token.content)
-  }
-
-  if (highlighted.indexOf('<pre') === 0) {
-    return `${highlighted}\n`
-  }
-
-  if (tokens[idx].map && tokens[idx].level === 0) {
-    const startline = tokens[idx].map[0] + 1
-    const endline = tokens[idx].map[1]
-    return `<pre class="part" data-startline="${startline}" data-endline="${endline}"><code${self.renderAttrs(token)}>${highlighted}</code></pre>\n`
-  }
-
-  return `<pre><code${self.renderAttrs(token)}>${highlighted}</code></pre>\n`
-}
-md.renderer.rules.code_block = (tokens, idx, options, env, self) => {
-  if (tokens[idx].map && tokens[idx].level === 0) {
-    const startline = tokens[idx].map[0] + 1
-    const endline = tokens[idx].map[1]
-    return `<pre class="part" data-startline="${startline}" data-endline="${endline}"><code>${md.utils.escapeHtml(tokens[idx].content)}</code></pre>\n`
-  }
-  return `<pre><code>${md.utils.escapeHtml(tokens[idx].content)}</code></pre>\n`
-}
-function renderContainer (tokens, idx, options, env, self) {
-  tokens[idx].attrJoin('role', 'alert')
-  tokens[idx].attrJoin('class', 'alert')
-  tokens[idx].attrJoin('class', `alert-${tokens[idx].info.trim()}`)
-  addPart(tokens, idx)
-  return self.renderToken(...arguments)
-}
-
-md.use(markdownitContainer, 'success', { render: renderContainer })
-md.use(markdownitContainer, 'info', { render: renderContainer })
-md.use(markdownitContainer, 'warning', { render: renderContainer })
-md.use(markdownitContainer, 'danger', { render: renderContainer })
-
-// FIXME: expose syncscroll to window
-window.syncscroll = true
-
-window.preventSyncScrollToEdit = false
-window.preventSyncScrollToView = false
-
-const editScrollThrottle = 5
-const viewScrollThrottle = 5
-const buildMapThrottle = 100
-
-let viewScrolling = false
-let editScrolling = false
-
-let editArea = null
-let viewArea = null
-let markdownArea = null
-
-export function setupSyncAreas (edit, view, markdown) {
-  editArea = edit
-  viewArea = view
-  markdownArea = markdown
-  editArea.on('scroll', _.throttle(syncScrollToView, editScrollThrottle))
-  viewArea.on('scroll', _.throttle(syncScrollToEdit, viewScrollThrottle))
-}
-
-let scrollMap, lineHeightMap, viewTop, viewBottom
-
-export function clearMap () {
-  scrollMap = null
-  lineHeightMap = null
-  viewTop = null
-  viewBottom = null
-}
-window.viewAjaxCallback = clearMap
-
-const buildMap = _.throttle(buildMapInner, buildMapThrottle)
-
-// Build offsets for each line (lines can be wrapped)
-// That's a bit dirty to process each line everytime, but ok for demo.
-// Optimizations are required only for big texts.
-function buildMapInner (callback) {
-  if (!viewArea || !markdownArea) return
-  let i, offset, nonEmptyList, pos, a, b, _lineHeightMap, linesCount, acc, _scrollMap
-
-  offset = viewArea.scrollTop() - viewArea.offset().top
-  _scrollMap = []
-  nonEmptyList = []
-  _lineHeightMap = []
-  viewTop = 0
-  viewBottom = viewArea[0].scrollHeight - viewArea.height()
-
-  acc = 0
-  const lines = window.editor.getValue().split('\n')
-  const lineHeight = window.editor.defaultTextHeight()
-  for (i = 0; i < lines.length; i++) {
-    const str = lines[i]
-
-    _lineHeightMap.push(acc)
-
-    if (str.length === 0) {
-      acc++
-      continue
-    }
-
-    const h = window.editor.heightAtLine(i + 1) - window.editor.heightAtLine(i)
-    acc += Math.round(h / lineHeight)
-  }
-  _lineHeightMap.push(acc)
-  linesCount = acc
-
-  for (i = 0; i < linesCount; i++) {
-    _scrollMap.push(-1)
-  }
-
-  nonEmptyList.push(0)
-    // make the first line go top
-  _scrollMap[0] = viewTop
-
-  const parts = markdownArea.find('.part').toArray()
-  for (i = 0; i < parts.length; i++) {
-    const $el = $(parts[i])
-    let t = $el.attr('data-startline') - 1
-    if (t === '') {
-      return
-    }
-    t = _lineHeightMap[t]
-    if (t !== 0 && t !== nonEmptyList[nonEmptyList.length - 1]) {
-      nonEmptyList.push(t)
-    }
-    _scrollMap[t] = Math.round($el.offset().top + offset - 10)
-  }
-
-  nonEmptyList.push(linesCount)
-  _scrollMap[linesCount] = viewArea[0].scrollHeight
-
-  pos = 0
-  for (i = 1; i < linesCount; i++) {
-    if (_scrollMap[i] !== -1) {
-      pos++
-      continue
-    }
-
-    a = nonEmptyList[pos]
-    b = nonEmptyList[pos + 1]
-    _scrollMap[i] = Math.round((_scrollMap[b] * (i - a) + _scrollMap[a] * (b - i)) / (b - a))
-  }
-
-  _scrollMap[0] = 0
-
-  scrollMap = _scrollMap
-  lineHeightMap = _lineHeightMap
-
-  if (window.loaded && callback) callback()
-}
-
-// sync view scroll progress to edit
-let viewScrollingTimer = null
-
-export function syncScrollToEdit (event, preventAnimate) {
-  if (window.currentMode !== modeType.both || !window.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 = window.editor.getScrollInfo()
-  const textHeight = window.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)
-  }
-
-  if (preventAnimate) {
-    editArea.scrollTop(posTo)
-  } else {
-    const posDiff = Math.abs(scrollInfo.top - posTo)
-    var duration = posDiff / 50
-    duration = duration >= 100 ? duration : 100
-    editArea.stop(true, true).animate({
-      scrollTop: posTo
-    }, duration, 'linear')
-  }
-
-  viewScrolling = true
-  clearTimeout(viewScrollingTimer)
-  viewScrollingTimer = setTimeout(viewScrollingTimeoutInner, duration * 1.5)
-}
-
-function viewScrollingTimeoutInner () {
-  viewScrolling = false
-}
-
-// sync edit scroll progress to view
-let editScrollingTimer = null
-
-export function syncScrollToView (event, preventAnimate) {
-  if (window.currentMode !== modeType.both || !window.syncscroll || !viewArea) return
-  if (window.preventSyncScrollToView) {
-    if (typeof preventSyncScrollToView === 'number') {
-      window.preventSyncScrollToView--
-    } else {
-      window.preventSyncScrollToView = false
-    }
-    return
-  }
-  if (!scrollMap || !lineHeightMap) {
-    buildMap(() => {
-      syncScrollToView(event, preventAnimate)
-    })
-    return
-  }
-  if (viewScrolling) return
-
-  let lineNo, posTo
-  let topDiffPercent, posToNextDiff
-  const scrollInfo = window.editor.getScrollInfo()
-  const textHeight = window.editor.defaultTextHeight()
-  lineNo = Math.floor(scrollInfo.top / textHeight)
-    // if reach the last line, will start lerp to the bottom
-  const diffToBottom = (scrollInfo.top + scrollInfo.clientHeight) - (scrollInfo.height - textHeight)
-  if (scrollInfo.height > scrollInfo.clientHeight && diffToBottom > 0) {
-    topDiffPercent = diffToBottom / textHeight
-    posTo = scrollMap[lineNo + 1]
-    posToNextDiff = (viewBottom - posTo) * topDiffPercent
-    posTo += Math.floor(posToNextDiff)
-  } else {
-    topDiffPercent = (scrollInfo.top % textHeight) / textHeight
-    posTo = scrollMap[lineNo]
-    posToNextDiff = (scrollMap[lineNo + 1] - posTo) * topDiffPercent
-    posTo += Math.floor(posToNextDiff)
-  }
-
-  if (preventAnimate) {
-    viewArea.scrollTop(posTo)
-  } else {
-    const posDiff = Math.abs(viewArea.scrollTop() - posTo)
-    var duration = posDiff / 50
-    duration = duration >= 100 ? duration : 100
-    viewArea.stop(true, true).animate({
-      scrollTop: posTo
-    }, duration, 'linear')
-  }
-
-  editScrolling = true
-  clearTimeout(editScrollingTimer)
-  editScrollingTimer = setTimeout(editScrollingTimeoutInner, duration * 1.5)
-}
-
-function editScrollingTimeoutInner () {
-  editScrolling = false
-}
-- 
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