Revert "Maintain scroll history"

This reverts commit 2e6bb53303.

src/text-editor-component.coffee

@@ -317,7 +317,7 @@ class TextEditorComponent
         pendingScrollTop = @pendingScrollTop
         @pendingScrollTop = null
         @presenter.setScrollTop(pendingScrollTop)
-        @presenter.commitScrollQueue()
+        @presenter.commitPendingScrollTopPosition()
 
   onHorizontalScroll: (scrollLeft) =>
     return if @updateRequested or scrollLeft is @presenter.getScrollLeft()
@@ -327,7 +327,7 @@ class TextEditorComponent
     unless animationFramePending
       @requestAnimationFrame =>
         @presenter.setScrollLeft(@pendingScrollLeft)
-        @presenter.commitScrollQueue()
+        @presenter.commitPendingScrollLeftPosition()
         @pendingScrollLeft = null
 
   onMouseWheel: (event) =>
@@ -613,11 +613,11 @@ class TextEditorComponent
 
       if mouseYDelta?
         @presenter.setScrollTop(@presenter.getScrollTop() + yDirection * scaleScrollDelta(mouseYDelta))
-        @presenter.commitScrollQueue()
+        @presenter.commitPendingScrollTopPosition()
 
       if mouseXDelta?
         @presenter.setScrollLeft(@presenter.getScrollLeft() + xDirection * scaleScrollDelta(mouseXDelta))
-        @presenter.commitScrollQueue()
+        @presenter.commitPendingScrollLeftPosition()
 
     scaleScrollDelta = (scrollDelta) ->
       Math.pow(scrollDelta / 2, 3) / 280

src/text-editor-presenter.coffee

@@ -3,23 +3,6 @@
 _ = require 'underscore-plus'
 Decoration = require './decoration'
 
-class ScrollQueue
-  constructor: ->
-    @queue = []
-    @committing = false
-
-  enqueue: (scrollAction) ->
-    if @committing
-      @queue.unshift(scrollAction)
-    else
-      @queue.push(scrollAction)
-
-  commit: ->
-    @committing = true
-    while scrollAction = @queue.shift()
-      scrollAction()
-    @committing = false
-
 module.exports =
 class TextEditorPresenter
   toggleCursorBlinkHandle: null
@@ -39,7 +22,6 @@ class TextEditorPresenter
     @measuredVerticalScrollbarWidth = verticalScrollbarWidth
     @gutterWidth ?= 0
     @tileSize ?= 6
-    @scrollQueue = new ScrollQueue
 
     @disposables = new CompositeDisposable
     @emitter = new Emitter
@@ -834,7 +816,7 @@ class TextEditorPresenter
   setScrollTop: (scrollTop) ->
     return unless scrollTop?
 
-    @scrollQueue.enqueue => @commitScrollTop(scrollTop)
+    @pendingScrollTop = scrollTop
 
     @shouldUpdateVerticalScrollState = true
     @shouldUpdateHiddenInputState = true
@@ -874,7 +856,7 @@ class TextEditorPresenter
   setScrollLeft: (scrollLeft) ->
     return unless scrollLeft?
 
-    @scrollQueue.enqueue => @commitScrollLeft(scrollLeft)
+    @pendingScrollLeft = scrollLeft
 
     @shouldUpdateHorizontalScrollState = true
     @shouldUpdateHiddenInputState = true
@@ -1491,54 +1473,7 @@ class TextEditorPresenter
       @emitDidUpdateState()
 
   didChangeScrollPosition: (position) ->
-    @scrollQueue.enqueue =>
-      {screenRange, options} = position
-
-      verticalScrollMarginInPixels = @getVerticalScrollMarginInPixels()
-      horizontalScrollMarginInPixels = @getHorizontalScrollMarginInPixels()
-
-      {top, left} = @pixelRectForScreenRange(new Range(screenRange.start, screenRange.start))
-      {top: endTop, left: endLeft, height: endHeight} = @pixelRectForScreenRange(new Range(screenRange.end, screenRange.end))
-      bottom = endTop + endHeight
-      right = endLeft
-
-      top += @getScrollTop()
-      bottom += @getScrollTop()
-      left += @getScrollLeft()
-      right += @getScrollLeft()
-
-      if options?.center
-        desiredScrollCenter = (top + bottom) / 2
-        unless @getScrollTop() < desiredScrollCenter < @getScrollBottom()
-          desiredScrollTop = desiredScrollCenter - @getClientHeight() / 2
-          desiredScrollBottom = desiredScrollCenter + @getClientHeight() / 2
-      else
-        desiredScrollTop = top - verticalScrollMarginInPixels
-        desiredScrollBottom = bottom + verticalScrollMarginInPixels
-
-      desiredScrollLeft = left - horizontalScrollMarginInPixels
-      desiredScrollRight = right + horizontalScrollMarginInPixels
-
-      if options?.reversed ? true
-        if desiredScrollBottom > @getScrollBottom()
-          @setScrollBottom(desiredScrollBottom)
-        if desiredScrollTop < @getScrollTop()
-          @setScrollTop(desiredScrollTop)
-
-        if desiredScrollRight > @getScrollRight()
-          @setScrollRight(desiredScrollRight)
-        if desiredScrollLeft < @getScrollLeft()
-          @setScrollLeft(desiredScrollLeft)
-      else
-        if desiredScrollTop < @getScrollTop()
-          @setScrollTop(desiredScrollTop)
-        if desiredScrollBottom > @getScrollBottom()
-          @setScrollBottom(desiredScrollBottom)
-
-        if desiredScrollLeft < @getScrollLeft()
-          @setScrollLeft(desiredScrollLeft)
-        if desiredScrollRight > @getScrollRight()
-          @setScrollRight(desiredScrollRight)
+    @pendingScrollLogicalPosition = position
 
     @shouldUpdateCursorsState = true
     @shouldUpdateCustomGutterDecorationState = true
@@ -1565,10 +1500,63 @@ class TextEditorPresenter
   getHorizontalScrollbarHeight: ->
     @horizontalScrollbarHeight
 
-  commitScrollLeft: (scrollLeft) ->
-    return unless scrollLeft?
+  commitPendingLogicalScrollPosition: ->
+    return unless @pendingScrollLogicalPosition?
 
-    scrollLeft = @constrainScrollLeft(scrollLeft)
+    {screenRange, options} = @pendingScrollLogicalPosition
+
+    verticalScrollMarginInPixels = @getVerticalScrollMarginInPixels()
+    horizontalScrollMarginInPixels = @getHorizontalScrollMarginInPixels()
+
+    {top, left} = @pixelRectForScreenRange(new Range(screenRange.start, screenRange.start))
+    {top: endTop, left: endLeft, height: endHeight} = @pixelRectForScreenRange(new Range(screenRange.end, screenRange.end))
+    bottom = endTop + endHeight
+    right = endLeft
+
+    top += @scrollTop
+    bottom += @scrollTop
+    left += @scrollLeft
+    right += @scrollLeft
+
+    if options?.center
+      desiredScrollCenter = (top + bottom) / 2
+      unless @getScrollTop() < desiredScrollCenter < @getScrollBottom()
+        desiredScrollTop = desiredScrollCenter - @getClientHeight() / 2
+        desiredScrollBottom = desiredScrollCenter + @getClientHeight() / 2
+    else
+      desiredScrollTop = top - verticalScrollMarginInPixels
+      desiredScrollBottom = bottom + verticalScrollMarginInPixels
+
+    desiredScrollLeft = left - horizontalScrollMarginInPixels
+    desiredScrollRight = right + horizontalScrollMarginInPixels
+
+    if options?.reversed ? true
+      if desiredScrollBottom > @getScrollBottom()
+        @setScrollBottom(desiredScrollBottom)
+      if desiredScrollTop < @getScrollTop()
+        @setScrollTop(desiredScrollTop)
+
+      if desiredScrollRight > @getScrollRight()
+        @setScrollRight(desiredScrollRight)
+      if desiredScrollLeft < @getScrollLeft()
+        @setScrollLeft(desiredScrollLeft)
+    else
+      if desiredScrollTop < @getScrollTop()
+        @setScrollTop(desiredScrollTop)
+      if desiredScrollBottom > @getScrollBottom()
+        @setScrollBottom(desiredScrollBottom)
+
+      if desiredScrollLeft < @getScrollLeft()
+        @setScrollLeft(desiredScrollLeft)
+      if desiredScrollRight > @getScrollRight()
+        @setScrollRight(desiredScrollRight)
+
+    @pendingScrollLogicalPosition = null
+
+  commitPendingScrollLeftPosition: ->
+    return unless @pendingScrollLeft?
+
+    scrollLeft = @constrainScrollLeft(@pendingScrollLeft)
     if scrollLeft isnt @scrollLeft and not Number.isNaN(scrollLeft)
       @realScrollLeft = scrollLeft
       @scrollLeft = Math.round(scrollLeft)
@@ -1579,10 +1567,10 @@ class TextEditorPresenter
 
     @pendingScrollLeft = null
 
-  commitScrollTop: (scrollTop) ->
-    return unless scrollTop?
+  commitPendingScrollTopPosition: ->
+    return unless @pendingScrollTop?
 
-    scrollTop = @constrainScrollTop(scrollTop)
+    scrollTop = @constrainScrollTop(@pendingScrollTop)
     if scrollTop isnt @scrollTop and not Number.isNaN(scrollTop)
       @realScrollTop = scrollTop
       @scrollTop = Math.round(scrollTop)
@@ -1592,8 +1580,10 @@ class TextEditorPresenter
       @didStartScrolling()
       @emitter.emit 'did-change-scroll-top', @scrollTop
 
+    @pendingScrollTop = null
+
   restoreScrollPosition: ->
-    return unless @hasPixelPositionRequirements()
+    return if @hasRestoredScrollPosition or not @hasPixelPositionRequirements()
 
     @setScrollTop(@scrollRow * @lineHeight) if @scrollRow?
     @setScrollLeft(@scrollColumn * @baseCharacterWidth) if @scrollColumn?
@@ -1601,11 +1591,10 @@ class TextEditorPresenter
     @hasRestoredScrollPosition = true
 
   updateScrollPosition: ->
-    @restoreScrollPosition() unless @hasRestoredScrollPosition
-    @commitScrollQueue()
-
-  commitScrollQueue: ->
-    @scrollQueue.commit()
+    @restoreScrollPosition()
+    @commitPendingLogicalScrollPosition()
+    @commitPendingScrollLeftPosition()
+    @commitPendingScrollTopPosition()
 
   onDidChangeScrollTop: (callback) ->
     @emitter.on 'did-change-scroll-top', callback