Add needsUpdate and needsAutoscroll properties to cursor views

Then in the editor, we update and autoscroll only the views that need it. Autoscrolling is suppressed when resetting the display so that we honor the scroll positions of the active EditSession.

spec/app/editor-spec.coffee

@@ -659,13 +659,11 @@ describe "Editor", ->
       it "places an additional cursor", ->
         editor.attachToDom()
         setEditorHeightInLines(editor, 5)
-        editor.renderedLines.trigger mousedownEvent(editor: editor, point: [3, 0])
+        editor.setCursorBufferPosition([3, 0])
         editor.scrollTop(editor.lineHeight * 6)
 
-        spyOn(editor, "scrollTo").andCallThrough()
-
         editor.renderedLines.trigger mousedownEvent(editor: editor, point: [6, 0], metaKey: true)
-        expect(editor.scrollTo.callCount).toBe 1
+        expect(editor.scrollTop()).toBe editor.lineHeight * (6 - editor.vScrollMargin)
 
         [cursor1, cursor2] = editor.getCursorViews()
         expect(cursor1.position()).toEqual(top: 3 * editor.lineHeight, left: 0)

src/app/cursor-view.coffee

@@ -12,15 +12,27 @@ class CursorView extends View
   editor: null
   visible: true
 
-  initialize: (@cursor, @editor, options={}) ->
+  needsUpdate: true
+  needsAutoscroll: true
+  needsRemoval: false
+
+  initialize: (@cursor, @editor) ->
     @cursor.on 'change-screen-position.cursor-view', (screenPosition, { bufferChange, autoscroll }) =>
-      @updateDisplay({autoscroll})
+      @needsUpdate = true
+      @needsAutoscroll = (autoscroll ? true) and @cursor?.isLastCursor()
+      @editor.updateDisplay()
+
+      # TODO: Move idle/active to the cursor model
       @removeIdleClassTemporarily() unless bufferChange
       @trigger 'cursor-move', {bufferChange}
 
-    @cursor.on 'change-visibility.cursor-view', (visible) => @setVisible(visible)
+    @cursor.on 'change-visibility.cursor-view', (visible) =>
+      @needsUpdate = true
+      @needsAutoscroll = visible and @cursor.isLastCursor()
+      @editor.updateDisplay()
+
     @cursor.on 'destroy.cursor-view', =>
-      @destroyed = true
+      @needsRemoval = true
       @editor.updateDisplay()
 
   remove: ->
@@ -28,29 +40,23 @@ class CursorView extends View
     @cursor.off('.cursor-view')
     super
 
-  updateDisplay: (options={}) ->
-    autoscroll = options.autoscroll ? true
+  updateDisplay: ->
     screenPosition = @getScreenPosition()
     pixelPosition = @getPixelPosition()
-    @css(pixelPosition)
-    @autoscroll() if @cursor.isLastCursor() and autoscroll
+
+    unless _.isEqual(@lastPixelPosition, pixelPosition)
+      changedPosition = true
+      @css(pixelPosition)
+
     @setVisible(@cursor.isVisible() and not @editor.isFoldedAtScreenRow(screenPosition.row))
 
   getPixelPosition: ->
     @editor.pixelPositionForScreenPosition(@getScreenPosition())
 
-  autoscroll: ->
-    @editor.scrollTo(@getPixelPosition())
-
   setVisible: (visible) ->
-    return if visible == @visible
-    @visible = visible
-
-    if @visible
-      @show()
-      @autoscroll()
-    else
-      @hide()
+    unless @visible == visible
+      @visible = visible
+      @toggle(@visible)
 
   getBufferPosition: ->
     @cursor.getBufferPosition()

src/app/editor.coffee

@@ -458,15 +458,15 @@ class Editor extends View
   getOpenBufferPaths: ->
     editSession.buffer.getPath() for editSession in @editSessions when editSession.buffer.getPath()?
 
-  scrollTop: (scrollTop, options) ->
+  scrollTop: (scrollTop, options={}) ->
     return @cachedScrollTop or 0 unless scrollTop?
-
+    updateDisplay = options.updateDisplay ? true
     maxScrollTop = @verticalScrollbar.prop('scrollHeight') - @verticalScrollbar.height()
     scrollTop = Math.floor(Math.max(0, Math.min(maxScrollTop, scrollTop)))
     return if scrollTop == @cachedScrollTop
     @cachedScrollTop = scrollTop
 
-    @updateDisplay(autoscroll: false) if @attached
+    @updateDisplay(autoscroll: false) if @attached and updateDisplay
 
     @renderedLines.css('top', -scrollTop)
     @underlayer.css('top', -scrollTop)
@@ -531,7 +531,7 @@ class Editor extends View
           element.removeClass('selected')
 
   setScrollPositionFromActiveEditSession: ->
-    @scrollTop(@activeEditSession.scrollTop ? 0)
+    @scrollTop(@activeEditSession.scrollTop ? 0, updateDisplay: false)
     @scrollView.scrollLeft(@activeEditSession.scrollLeft ? 0)
 
   saveActiveEditSession: ->
@@ -655,17 +655,17 @@ class Editor extends View
   removeCursorView: (cursorView) ->
     _.remove(@cursorViews, cursorView)
 
-  updateCursorViews: (options)->
+  updateCursorViews: ->
     if @newCursors.length > 0
       @addCursorView(cursor) for cursor in @newCursors
       @syncCursorAnimations()
       @newCursors = []
 
     for cursorView in @getCursorViews()
-      if cursorView.destroyed
+      if cursorView.needsRemoval
         cursorView.remove()
-      else
-        cursorView.updateDisplay(options)
+      else if cursorView.needsUpdate
+        cursorView.updateDisplay()
 
   updateSelectionViews: ->
     if @newSelections.length > 0
@@ -763,15 +763,20 @@ class Editor extends View
 
     @newCursors = @activeEditSession.getCursors()
     @newSelections = @activeEditSession.getSelections()
-    @updateDisplay(autoscroll: false)
+    @updateDisplay(suppressAutoScroll: true)
 
-  updateDisplay: (options) ->
+  updateDisplay: (options={}) ->
     return unless @attached
-
-    @updateCursorViews(options)
+    @updateCursorViews()
     @updateSelectionViews()
+    @autoscroll(options)
     @updateRenderedLines()
 
+  autoscroll: (options={}) ->
+    for cursorView in @getCursorViews() when cursorView.needsAutoscroll
+      @scrollTo(cursorView.getPixelPosition()) unless options.suppressAutoScroll
+      cursorView.needsAutoscroll = false
+
   updateRenderedLines: ->
     firstVisibleScreenRow = @getFirstVisibleScreenRow()
     lastVisibleScreenRow = @getLastVisibleScreenRow()