Tell marker head observers if a move was caused by a buffer change

This is used by cursor to only autoscroll when the marker head is
explicitly moved, so that passive movements caused by buffer insertions
don't trigger autoscrolling.

spec/app/buffer-spec.coffee

@@ -720,13 +720,17 @@ describe 'Buffer', ->
         beforeEach ->
           observeHandler = jasmine.createSpy("observeHandler")
 
-        it "calls the given callback whenever the marker's head position changes", ->
+        it "calls the given callback whenever the marker's head position changes with the position and whether or not the move was caused by a buffer change", ->
           marker = buffer.markRange([[4, 20], [4, 23]])
           buffer.observeMarkerHeadPosition(marker, observeHandler)
 
           buffer.setMarkerHeadPosition(marker, [6, 2])
           expect(observeHandler).toHaveBeenCalled()
-          expect(observeHandler.argsForCall[0][0]).toEqual [6, 2]
+          expect(observeHandler.argsForCall[0]).toEqual [[6, 2], false]
+          observeHandler.reset()
+
+          buffer.insert([6, 0], '...')
+          expect(observeHandler.argsForCall[0]).toEqual [[6, 5], true]
 
         it "allows the observation subscription to be cancelled", ->
           marker = buffer.markRange([[4, 20], [4, 23]])

spec/app/display-buffer-spec.coffee

@@ -620,27 +620,27 @@ fdescribe "DisplayBuffer", ->
         observeHandler = jasmine.createSpy("observeHandler")
 
       describe ".observeMarkerHeadScreenPosition(marker, callback)", ->
-        it "calls the callback whenever the markers head's screen position changes", ->
+        it "calls the callback whenever the markers head's screen position changes with the new position and whether it was precipitated by a buffer change", ->
           marker = displayBuffer.markScreenRange([[5, 4], [5, 10]])
           displayBuffer.observeMarkerHeadScreenPosition(marker, observeHandler)
           displayBuffer.setMarkerHeadScreenPosition(marker, [8, 20])
           expect(observeHandler).toHaveBeenCalled()
-          expect(observeHandler.argsForCall[0][0]).toEqual [8, 20]
+          expect(observeHandler.argsForCall[0]).toEqual [[8, 20], false]
           observeHandler.reset()
 
           buffer.insert([11, 0], '...')
           expect(observeHandler).toHaveBeenCalled()
-          expect(observeHandler.argsForCall[0][0]).toEqual [8, 23]
+          expect(observeHandler.argsForCall[0]).toEqual [[8, 23], true]
           observeHandler.reset()
 
           displayBuffer.unfoldBufferRow(4)
           expect(observeHandler).toHaveBeenCalled()
-          expect(observeHandler.argsForCall[0][0]).toEqual [11, 23]
+          expect(observeHandler.argsForCall[0]).toEqual [[11, 23], false]
           observeHandler.reset()
 
           displayBuffer.foldBufferRow(4)
           expect(observeHandler).toHaveBeenCalled()
-          expect(observeHandler.argsForCall[0][0]).toEqual [8, 23]
+          expect(observeHandler.argsForCall[0]).toEqual [[8, 23], false]
 
         it "does not call the callback for screen changes that don't change the position of the marker", ->
           marker = displayBuffer.markScreenPosition([3, 4])

src/app/buffer-marker.coffee

@@ -38,7 +38,7 @@ class BufferMarker
   setHeadPosition: (headPosition, options={}) ->
     @headPosition = Point.fromObject(headPosition)
     @headPosition = @buffer.clipPosition(@headPosition) if options.clip ? true
-    observer(@headPosition) for observer in @headPositionObservers
+    observer(@headPosition, !!options.bufferChanged) for observer in @headPositionObservers
     @headPosition
 
   setTailPosition: (tailPosition, options={}) ->
@@ -81,8 +81,8 @@ class BufferMarker
       [@id]
 
   handleBufferChange: (bufferChange) ->
-    @setHeadPosition(@updatePosition(@headPosition, bufferChange, false), clip: false)
-    @setTailPosition(@updatePosition(@tailPosition, bufferChange, true), clip: false) if @tailPosition
+    @setHeadPosition(@updatePosition(@headPosition, bufferChange, false), clip: false, bufferChanged: true)
+    @setTailPosition(@updatePosition(@tailPosition, bufferChange, true), clip: false, bufferChanged: true) if @tailPosition
 
   updatePosition: (position, bufferChange, isFirstPoint) ->
     { oldRange, newRange } = bufferChange

src/app/cursor.coffee

@@ -12,8 +12,8 @@ class Cursor
   needsAutoscroll: null
 
   constructor: ({@editSession, @marker}) ->
-    @editSession.observeMarkerHeadScreenPosition @marker, (screenPosition) =>
-      @needsAutoscroll ?= @isLastCursor()
+    @editSession.observeMarkerHeadScreenPosition @marker, (screenPosition, bufferChanged) =>
+      @needsAutoscroll ?= @isLastCursor() and !bufferChanged
       @trigger 'moved', screenPosition
       @editSession.trigger 'cursor-moved', screenPosition
     @needsAutoscroll = true

src/app/display-buffer.coffee

@@ -372,9 +372,9 @@ class DisplayBuffer
     @markerScreenPositionObservers[id] ?= { head: [], tail: [] }
     @cacheMarkerScreenPositions(id) unless @markerScreenPositions[id]
     @markerScreenPositionObservers[id].head.push(callback)
-    subscription = @buffer.observeMarkerHeadPosition id, (bufferPosition) =>
+    subscription = @buffer.observeMarkerHeadPosition id, (bufferPosition, bufferChanged) =>
       @cacheMarkerScreenPositions(id)
-      callback(@getMarkerHeadScreenPosition(id))
+      callback(@getMarkerHeadScreenPosition(id), bufferChanged)
 
     cancel: =>
       subscription.cancel()
@@ -392,7 +392,7 @@ class DisplayBuffer
       currentHeadPosition = @getMarkerHeadScreenPosition(id)
       unless currentHeadPosition.isEqual(head)
         @cacheMarkerScreenPositions(id)
-        observer(currentHeadPosition) for observer in @markerScreenPositionObservers[id].head
+        observer(currentHeadPosition, false) for observer in @markerScreenPositionObservers[id].head
 
   destroy: ->
     @tokenizedBuffer.destroy()