Don't defer updates with setImmediate in animation frames

I previously thought this was okay, but now I'm experiencing jitter when
scrolling with the trackpad when updates are deferred, and the frames
seem jagged. So this commit restores a synchronous approach to display
updates whenever we use animation frames.

spec/editor-component-spec.coffee

@@ -84,7 +84,6 @@ describe "EditorComponent", ->
 
       verticalScrollbarNode.scrollTop = 4.5 * lineHeightInPixels
       verticalScrollbarNode.dispatchEvent(new UIEvent('scroll'))
-      runSetImmediateCallbacks()
 
       expect(linesNode.style['-webkit-transform']).toBe "translate3d(0px, #{-4.5 * lineHeightInPixels}px, 0px)"
       expect(node.querySelectorAll('.line').length).toBe 6 + 4 # margin above and below
@@ -329,7 +328,6 @@ describe "EditorComponent", ->
 
       verticalScrollbarNode.scrollTop = 2.5 * lineHeightInPixels
       verticalScrollbarNode.dispatchEvent(new UIEvent('scroll'))
-      runSetImmediateCallbacks()
 
       expect(node.querySelectorAll('.line-number').length).toBe 6 + 4 + 1 # line overdraw margin above/below + dummy line number
 
@@ -520,7 +518,6 @@ describe "EditorComponent", ->
       verticalScrollbarNode.dispatchEvent(new UIEvent('scroll'))
       horizontalScrollbarNode.scrollLeft = 3.5 * charWidth
       horizontalScrollbarNode.dispatchEvent(new UIEvent('scroll'))
-      runSetImmediateCallbacks()
 
       cursorNodes = node.querySelectorAll('.cursor')
       expect(cursorNodes.length).toBe 2
@@ -877,7 +874,6 @@ describe "EditorComponent", ->
 
       verticalScrollbarNode.scrollTop = 3.5 * lineHeightInPixels
       verticalScrollbarNode.dispatchEvent(new UIEvent('scroll'))
-      runSetImmediateCallbacks()
 
       regions = node.querySelectorAll('.some-highlight .region')
 
@@ -1397,36 +1393,30 @@ describe "EditorComponent", ->
         expect(horizontalScrollbarNode.scrollLeft).toBe 0
 
         node.dispatchEvent(new WheelEvent('mousewheel', wheelDeltaX: -5, wheelDeltaY: -10))
-        runSetImmediateCallbacks()
         expect(verticalScrollbarNode.scrollTop).toBe 10
         expect(horizontalScrollbarNode.scrollLeft).toBe 0
 
         node.dispatchEvent(new WheelEvent('mousewheel', wheelDeltaX: -15, wheelDeltaY: -5))
-        runSetImmediateCallbacks()
         expect(verticalScrollbarNode.scrollTop).toBe 10
         expect(horizontalScrollbarNode.scrollLeft).toBe 15
 
       it "updates the scrollLeft or scrollTop according to the scroll sensitivity", ->
         atom.config.set('editor.scrollSensitivity', 50)
         node.dispatchEvent(new WheelEvent('mousewheel', wheelDeltaX: -5, wheelDeltaY: -10))
-        runSetImmediateCallbacks()
         expect(horizontalScrollbarNode.scrollLeft).toBe 0
 
         node.dispatchEvent(new WheelEvent('mousewheel', wheelDeltaX: -15, wheelDeltaY: -5))
-        runSetImmediateCallbacks()
         expect(verticalScrollbarNode.scrollTop).toBe 5
         expect(horizontalScrollbarNode.scrollLeft).toBe 7
 
       it "uses the previous scrollSensitivity when the value is not an int", ->
         atom.config.set('editor.scrollSensitivity', 'nope')
         node.dispatchEvent(new WheelEvent('mousewheel', wheelDeltaX: 0, wheelDeltaY: -10))
-        runSetImmediateCallbacks()
         expect(verticalScrollbarNode.scrollTop).toBe 10
 
       it "parses negative scrollSensitivity values as positive", ->
         atom.config.set('editor.scrollSensitivity', -50)
         node.dispatchEvent(new WheelEvent('mousewheel', wheelDeltaX: 0, wheelDeltaY: -10))
-        runSetImmediateCallbacks()
         expect(verticalScrollbarNode.scrollTop).toBe 5
 
     describe "when the mousewheel event's target is a line", ->

src/editor-component.coffee

@@ -26,6 +26,8 @@ EditorComponent = React.createClass
   pendingScrollLeft: null
   selectOnMouseMove: false
   updateRequested: false
+  updatesPaused: false
+  updateRequestedWhilePaused: false
   cursorsMoved: false
   selectionChanged: false
   selectionAdded: false
@@ -203,6 +205,10 @@ EditorComponent = React.createClass
     @remeasureCharacterWidthsIfNeeded(prevState)
 
   requestUpdate: ->
+    if @updatesPaused
+      @updateRequestedWhilePaused = true
+      return
+
     if @performSyncUpdates ? EditorComponent.performSyncUpdates
       @forceUpdate()
     else unless @updateRequested
@@ -211,6 +217,15 @@ EditorComponent = React.createClass
         @updateRequested = false
         @forceUpdate() if @isMounted()
 
+  requestAnimationFrame: (fn) ->
+    @updatesPaused = true
+    requestAnimationFrame =>
+      fn()
+      @updatesPaused = false
+      if @updateRequestedWhilePaused and @isMounted()
+        @updateRequestedWhilePaused = false
+        @forceUpdate()
+
   getRenderedRowRange: ->
     {editor, lineOverdrawMargin} = @props
     [visibleStartRow, visibleEndRow] = editor.getVisibleRowRange()
@@ -519,7 +534,7 @@ EditorComponent = React.createClass
     @pendingScrollTop = scrollTop
     unless animationFramePending
       @pauseScrollViewMeasurement()
-      requestAnimationFrame =>
+      @requestAnimationFrame =>
         pendingScrollTop = @pendingScrollTop
         @pendingScrollTop = null
         @props.editor.setScrollTop(pendingScrollTop)
@@ -533,7 +548,7 @@ EditorComponent = React.createClass
     @pendingScrollLeft = scrollLeft
     unless animationFramePending
       @pauseScrollViewMeasurement()
-      requestAnimationFrame =>
+      @requestAnimationFrame =>
         @props.editor.setScrollLeft(@pendingScrollLeft)
         @pendingScrollLeft = null
 
@@ -555,7 +570,7 @@ EditorComponent = React.createClass
 
     unless animationFramePending
       @pauseScrollViewMeasurement()
-      requestAnimationFrame =>
+      @requestAnimationFrame =>
         {editor} = @props
         editor.setScrollTop(editor.getScrollTop() + @pendingVerticalScrollDelta)
         editor.setScrollLeft(editor.getScrollLeft() + @pendingHorizontalScrollDelta)
@@ -656,7 +671,7 @@ EditorComponent = React.createClass
   onScrollTopChanged: ->
     @scrollingVertically = true
     @requestUpdate()
-    @onStoppedScrollingAfterDelay ?= debounce(@onStoppedScrolling, 100)
+    @onStoppedScrollingAfterDelay ?= debounce(@onStoppedScrolling, 200)
     @onStoppedScrollingAfterDelay()
 
   onStoppedScrolling: ->
@@ -684,7 +699,7 @@ EditorComponent = React.createClass
     lastMousePosition = {}
     animationLoop = =>
       @pauseScrollViewMeasurement()
-      requestAnimationFrame =>
+      @requestAnimationFrame =>
         if dragging
           screenPosition = @screenPositionForMouseEvent(lastMousePosition)
           dragHandler(screenPosition)
@@ -725,7 +740,7 @@ EditorComponent = React.createClass
     return if @scrollViewMeasurementRequested
 
     @scrollViewMeasurementRequested = true
-    requestAnimationFrame =>
+    @requestAnimationFrame =>
       @scrollViewMeasurementRequested = false
       @measureScrollView()