Move selection background region calculation into React component

src/editor-scroll-view-component.coffee

@@ -40,7 +40,7 @@ EditorScrollViewComponent = React.createClass
         selectionChanged
       }
       div className: 'underlayer',
-        SelectionBackgroundsComponent({editor, scrollTop, scrollLeft})
+        SelectionBackgroundsComponent({editor, lineHeight, scrollTop})
 
   componentDidMount: ->
     @getDOMNode().addEventListener 'overflowchanged', @onOverflowChanged

src/selection-backgrounds-component.coffee

@@ -6,13 +6,19 @@ SelectionBackgroundsComponent = React.createClass
   displayName: 'SelectionBackgroundsComponent'
 
   render: ->
-    {editor, scrollTop} = @props
+    {editor, lineHeight, scrollTop} = @props
 
     div className: 'selections',
       if @isMounted()
         for selection in editor.getSelections()
-          if backgroundRect = selection.getBackgroundRect()
-            {top, left, right, height} = backgroundRect
-            WebkitTransform = "translate3d(0px, #{top - scrollTop}px, 0px)"
-            div className: 'selection', key: selection.id,
-              div className: 'region', style: {left, right, height, WebkitTransform}
+          {start, end} = selection.getScreenRange()
+          continue if start.row is end.row
+
+          height = (end.row - start.row) * lineHeight
+          top = (start.row * lineHeight) - scrollTop
+          left = 0
+          right = 0
+          WebkitTransform = "translate3d(0px, #{top}px, 0px)"
+
+          div className: 'selection', key: selection.id,
+            div className: 'region', style: {left, right, height, WebkitTransform}

src/selection.coffee

@@ -591,17 +591,6 @@ class Selection extends Model
   compare: (otherSelection) ->
     @getBufferRange().compare(otherSelection.getBufferRange())
 
-  getBackgroundRect: ->
-    {start, end} = @getScreenRange()
-    return if start.row is end.row
-
-    lineHeight = @editor.getLineHeight()
-    height = (end.row - start.row) * lineHeight
-    top = start.row * lineHeight
-    left = 0
-    right = 0
-    {top, left, right, height}
-
   screenRangeChanged: ->
     screenRange = @getScreenRange()
     @emit 'screen-range-changed', screenRange