Merge pull request #13202 from atom/mb-fix-resize-flicker

Fix flicker in soft-wrapped files when resizing editors

spec/text-editor-presenter-spec.coffee

@@ -165,23 +165,6 @@ describe "TextEditorPresenter", ->
         expect(stateFn(presenter).tiles[10]).toBeUndefined()
         expect(stateFn(presenter).tiles[12]).toBeUndefined()
 
-      it "excludes invalid tiles for screen rows to measure", ->
-        presenter = buildPresenter(explicitHeight: 6, scrollTop: 0, lineHeight: 1, tileSize: 2)
-        presenter.setScreenRowsToMeasure([20, 30]) # unexisting rows
-
-        expect(stateFn(presenter).tiles[0]).toBeDefined()
-        expect(stateFn(presenter).tiles[2]).toBeDefined()
-        expect(stateFn(presenter).tiles[4]).toBeDefined()
-        expect(stateFn(presenter).tiles[6]).toBeDefined()
-        expect(stateFn(presenter).tiles[8]).toBeUndefined()
-        expect(stateFn(presenter).tiles[10]).toBeUndefined()
-        expect(stateFn(presenter).tiles[12]).toBeUndefined()
-
-        presenter.setScreenRowsToMeasure([12])
-        buffer.deleteRows(12, 13)
-
-        expect(stateFn(presenter).tiles[12]).toBeUndefined()
-
       describe "when there are block decorations", ->
         it "computes each tile's height and scrollTop based on block decorations' height", ->
           presenter = buildPresenter(explicitHeight: 120, scrollTop: 0, lineHeight: 10, tileSize: 2)

src/text-editor-presenter.coffee

@@ -306,9 +306,6 @@ class TextEditorPresenter
   getEndTileRow: ->
     @tileForRow(@endRow ? 0)
 
-  isValidScreenRow: (screenRow) ->
-    screenRow >= 0 and screenRow < @model.getApproximateScreenLineCount()
-
   getScreenRowsToRender: ->
     startRow = @getStartTileRow()
     endRow = @getEndTileRow() + @tileSize
@@ -320,7 +317,7 @@ class TextEditorPresenter
     if @screenRowsToMeasure?
       screenRows.push(@screenRowsToMeasure...)
 
-    screenRows = screenRows.filter @isValidScreenRow.bind(this)
+    screenRows = screenRows.filter (row) -> row >= 0
     screenRows.sort (a, b) -> a - b
     _.uniq(screenRows, true)
 
@@ -395,19 +392,17 @@ class TextEditorPresenter
       visibleTiles[tileStartRow] = true
       zIndex++
 
-    if @mouseWheelScreenRow? and 0 <= @mouseWheelScreenRow < @model.getApproximateScreenLineCount()
-      mouseWheelTile = @tileForRow(@mouseWheelScreenRow)
-
-      unless visibleTiles[mouseWheelTile]?
-        @lineNumberGutter.tiles[mouseWheelTile].display = "none"
-        @state.content.tiles[mouseWheelTile].display = "none"
-        visibleTiles[mouseWheelTile] = true
+    mouseWheelTileId = @tileForRow(@mouseWheelScreenRow) if @mouseWheelScreenRow?
 
     for id, tile of @state.content.tiles
       continue if visibleTiles.hasOwnProperty(id)
 
-      delete @state.content.tiles[id]
-      delete @lineNumberGutter.tiles[id]
+      if Number(id) is mouseWheelTileId
+        @state.content.tiles[id].display = "none"
+        @lineNumberGutter.tiles[id].display = "none"
+      else
+        delete @state.content.tiles[id]
+        delete @lineNumberGutter.tiles[id]
 
   updateLinesState: (tileState, screenRows) ->
     tileState.lines ?= {}

src/text-editor.coffee

@@ -222,6 +222,7 @@ class TextEditor extends Model
       @backgroundWorkHandle = null
 
   update: (params) ->
+    currentSoftWrapColumn = @getSoftWrapColumn()
     displayLayerParams = {}
 
     for param in Object.keys(params)
@@ -272,12 +273,16 @@ class TextEditor extends Model
         when 'softWrapAtPreferredLineLength'
           if value isnt @softWrapAtPreferredLineLength
             @softWrapAtPreferredLineLength = value
-            displayLayerParams.softWrapColumn = @getSoftWrapColumn() if @isSoftWrapped()
+            softWrapColumn = @getSoftWrapColumn()
+            if softWrapColumn isnt currentSoftWrapColumn
+              displayLayerParams.softWrapColumn = softWrapColumn
 
         when 'preferredLineLength'
           if value isnt @preferredLineLength
             @preferredLineLength = value
-            displayLayerParams.softWrapColumn = @getSoftWrapColumn() if @isSoftWrapped()
+            softWrapColumn = @getSoftWrapColumn()
+            if softWrapColumn isnt currentSoftWrapColumn
+              displayLayerParams.softWrapColumn = softWrapColumn
 
         when 'mini'
           if value isnt @mini
@@ -322,12 +327,16 @@ class TextEditor extends Model
         when 'editorWidthInChars'
           if value > 0 and value isnt @editorWidthInChars
             @editorWidthInChars = value
-            displayLayerParams.softWrapColumn = @getSoftWrapColumn() if @isSoftWrapped()
+            softWrapColumn = @getSoftWrapColumn()
+            if softWrapColumn isnt currentSoftWrapColumn
+              displayLayerParams.softWrapColumn = softWrapColumn
 
         when 'width'
           if value isnt @width
             @width = value
-            displayLayerParams.softWrapColumn = @getSoftWrapColumn() if @isSoftWrapped()
+            softWrapColumn = @getSoftWrapColumn()
+            if softWrapColumn isnt currentSoftWrapColumn
+              displayLayerParams.softWrapColumn = softWrapColumn
 
         when 'scrollPastEnd'
           if value isnt @scrollPastEnd