Use presenter state for placeholder text

Signed-off-by: Nathan Sobo <nathan@github.com>

spec/text-editor-presenter-spec.coffee

@@ -197,6 +197,18 @@ describe "TextEditorPresenter", ->
           expectStateUpdate presenter, -> editor.setMini(true)
           expect(presenter.state.content.backgroundColor).toBeNull()
 
+      describe ".placeholderText", ->
+        it "is present when the editor has no text", ->
+          editor.setPlaceholderText("the-placeholder-text")
+          presenter = new TextEditorPresenter(model: editor)
+          expect(presenter.state.content.placeholderText).toBeNull()
+
+          expectStateUpdate presenter, -> editor.setText("")
+          expect(presenter.state.content.placeholderText).toBe "the-placeholder-text"
+
+          expectStateUpdate presenter, -> editor.setPlaceholderText("new-placeholder-text")
+          expect(presenter.state.content.placeholderText).toBe "new-placeholder-text"
+
       describe ".lines", ->
         lineStateForScreenRow = (presenter, screenRow) ->
           presenter.state.content.lines[presenter.model.tokenizedLineForScreenRow(screenRow).id]

src/lines-component.coffee

@@ -20,12 +20,12 @@ LinesComponent = React.createClass
     {presenter} = @props
 
     if presenter?
-      {editor, presenter, placeholderText} = @props
+      {editor, presenter} = @props
 
       @oldState ?= {content: {lines: {}}}
       @newState = presenter.state
       {scrollHeight} = @newState
-      {scrollWidth, backgroundColor} = @newState.content
+      {scrollWidth, backgroundColor, placeholderText} = @newState.content
 
       style =
         height: scrollHeight

src/text-editor-component.coffee

@@ -58,7 +58,6 @@ TextEditorComponent = React.createClass
     if @performedInitialMeasurement
       [renderedStartRow, renderedEndRow] = @getRenderedRowRange()
 
-      placeholderText = editor.getPlaceholderText() if editor.isEmpty()
       visible = @isVisible()
 
       {scrollHeight, scrollTop} = @presenter.state
@@ -99,7 +98,7 @@ TextEditorComponent = React.createClass
 
         LinesComponent {
           ref: 'lines', @presenter, editor, hostElement, @useHardwareAcceleration, useShadowDOM,
-          mouseWheelScreenRow, visible, placeholderText, @backgroundColor
+          mouseWheelScreenRow, visible, @backgroundColor
         }
 
         ScrollbarComponent
@@ -282,7 +281,6 @@ TextEditorComponent = React.createClass
     @subscribe editor.observeDecorations(@onDecorationAdded)
     @subscribe editor.onDidRemoveDecoration(@onDecorationRemoved)
     @subscribe editor.onDidChangeCharacterWidths(@onCharacterWidthsChanged)
-    @subscribe editor.onDidChangePlaceholderText(@onPlaceholderTextChanged)
     @subscribe editor.$scrollTop.changes, @onScrollTopChanged
     @subscribe editor.$scrollLeft.changes, @onScrollLeftChanged
     @subscribe editor.$verticalScrollbarWidth.changes, @requestUpdate
@@ -648,9 +646,6 @@ TextEditorComponent = React.createClass
   onCharacterWidthsChanged: (@scopedCharacterWidthsChangeCount) ->
     @requestUpdate()
 
-  onPlaceholderTextChanged: ->
-    @requestUpdate()
-
   handleDragUntilMouseUp: (event, dragHandler) ->
     {editor} = @props
     dragging = false

src/text-editor-presenter.coffee

@@ -31,6 +31,7 @@ class TextEditorPresenter
     @disposables.add @model.onDidChange(@updateState.bind(this))
     @disposables.add @model.onDidChangeSoftWrapped(@updateState.bind(this))
     @disposables.add @model.onDidChangeGrammar(@updateContentState.bind(this))
+    @disposables.add @model.onDidChangePlaceholderText(@updateContentState.bind(this))
     @disposables.add @model.onDidChangeMini =>
       @updateContentState()
       @updateLinesState()
@@ -76,6 +77,7 @@ class TextEditorPresenter
     @state.content.scrollLeft = @getScrollLeft()
     @state.content.indentGuidesVisible = not @model.isMini() and atom.config.get('editor.showIndentGuide', scope: @model.getRootScopeDescriptor())
     @state.content.backgroundColor = if @model.isMini() then null else @getBackgroundColor()
+    @state.content.placeholderText = if @model.isEmpty() then @model.getPlaceholderText() else null
     @emitter.emit 'did-update-state'
 
   updateLinesState: ->