Add width to lines state based on the computed scrollWidth

This is based on the ::baseCharacterWidth property for now. To be fully
correct, we need to base the scrollWidth on the actual width of
individual characters.

spec/text-editor-presenter-spec.coffee

@@ -79,6 +79,23 @@ describe "TextEditorPresenter", ->
 
         # rows beyond the end of the content are not rendered
 
+      it "uses the computed scrollWidth as the length of each line", ->
+        line0 = editor.tokenizedLineForScreenRow(0)
+        line1 = editor.tokenizedLineForScreenRow(1)
+        line2 = editor.tokenizedLineForScreenRow(2)
+
+        maxLineLength = editor.getMaxScreenLineLength()
+
+        presenter = new TextEditorPresenter(model: editor, clientHeight: 25, clientWidth: 50, scrollTop: 0, baseCharacterWidth: 10, lineHeight: 10, lineOverdrawMargin: 0)
+        expect(presenter.state.lines[line0.id].width).toBe 10 * maxLineLength
+        expect(presenter.state.lines[line1.id].width).toBe 10 * maxLineLength
+        expect(presenter.state.lines[line2.id].width).toBe 10 * maxLineLength
+
+        presenter = new TextEditorPresenter(model: editor, clientHeight: 25, clientWidth: 10 * maxLineLength + 20, scrollTop: 0, baseCharacterWidth: 10, lineHeight: 10, lineOverdrawMargin: 0)
+        expect(presenter.state.lines[line0.id].width).toBe 10 * maxLineLength + 20
+        expect(presenter.state.lines[line1.id].width).toBe 10 * maxLineLength + 20
+        expect(presenter.state.lines[line2.id].width).toBe 10 * maxLineLength + 20
+
     describe "when ::scrollTop changes", ->
       it "updates the lines that are visible on screen", ->
         presenter = new TextEditorPresenter(model: editor, clientHeight: 25, scrollTop: 0, lineHeight: 10, lineOverdrawMargin: 1)
@@ -224,3 +241,41 @@ describe "TextEditorPresenter", ->
           tokens: line3.tokens
           top: 10 * 3
         }
+
+    describe "when the ::clientWidth changes", ->
+      it "updates the width of the lines if it changes the ::scrollWidth", ->
+        line0 = editor.tokenizedLineForScreenRow(0)
+        line1 = editor.tokenizedLineForScreenRow(1)
+        line2 = editor.tokenizedLineForScreenRow(2)
+
+        maxLineLength = editor.getMaxScreenLineLength()
+
+        presenter = new TextEditorPresenter(model: editor, clientHeight: 25, clientWidth: 50, scrollTop: 0, scrollWidth: 70, lineHeight: 10, baseCharacterWidth: 10, lineOverdrawMargin: 0)
+        expect(presenter.state.lines[line0.id].width).toBe 10 * maxLineLength
+        expect(presenter.state.lines[line1.id].width).toBe 10 * maxLineLength
+        expect(presenter.state.lines[line2.id].width).toBe 10 * maxLineLength
+
+        presenter.setClientWidth(10 * maxLineLength + 20)
+
+        expect(presenter.state.lines[line0.id].width).toBe 10 * maxLineLength + 20
+        expect(presenter.state.lines[line1.id].width).toBe 10 * maxLineLength + 20
+        expect(presenter.state.lines[line2.id].width).toBe 10 * maxLineLength + 20
+
+    describe "when the ::baseCharacterWidth changes", ->
+      it "updates the width of the lines if it changes the ::scrollWidth", ->
+        line0 = editor.tokenizedLineForScreenRow(0)
+        line1 = editor.tokenizedLineForScreenRow(1)
+        line2 = editor.tokenizedLineForScreenRow(2)
+
+        maxLineLength = editor.getMaxScreenLineLength()
+
+        presenter = new TextEditorPresenter(model: editor, clientHeight: 25, clientWidth: 50, scrollTop: 0, scrollWidth: 70, lineHeight: 10, baseCharacterWidth: 10, lineOverdrawMargin: 0)
+        expect(presenter.state.lines[line0.id].width).toBe 10 * maxLineLength
+        expect(presenter.state.lines[line1.id].width).toBe 10 * maxLineLength
+        expect(presenter.state.lines[line2.id].width).toBe 10 * maxLineLength
+
+        presenter.setBaseCharacterWidth(15)
+
+        expect(presenter.state.lines[line0.id].width).toBe 15 * maxLineLength
+        expect(presenter.state.lines[line1.id].width).toBe 15 * maxLineLength
+        expect(presenter.state.lines[line2.id].width).toBe 15 * maxLineLength

src/text-editor-presenter.coffee

@@ -2,7 +2,7 @@
 
 module.exports =
 class TextEditorPresenter
-  constructor: ({@model, @clientHeight, @scrollTop, @lineHeight, @lineOverdrawMargin}) ->
+  constructor: ({@model, @clientHeight, @clientWidth, @scrollTop, @lineHeight, @baseCharacterWidth, @lineOverdrawMargin}) ->
     @disposables = new CompositeDisposable
     @state = {}
     @subscribeToModel()
@@ -41,12 +41,14 @@ class TextEditorPresenter
     lineState = @state.lines[line.id]
     lineState.screenRow = row
     lineState.top = row * @lineHeight
+    lineState.width = @getScrollWidth()
 
   buildLineState: (row, line) ->
     @state.lines[line.id] =
       screenRow: row
       tokens: line.tokens
       top: row * @lineHeight
+      width: @getScrollWidth()
 
   getStartRow: ->
     startRow = Math.floor(@scrollTop / @lineHeight) - @lineOverdrawMargin
@@ -56,11 +58,20 @@ class TextEditorPresenter
     endRow = @getStartRow() + Math.ceil(@clientHeight / @lineHeight) + @lineOverdrawMargin
     Math.min(@model.getScreenLineCount(), endRow)
 
+  getScrollWidth: ->
+    Math.max(@model.getMaxScreenLineLength() * @baseCharacterWidth, @clientWidth)
+
   setScrollTop: (@scrollTop) ->
     @updateLinesState()
 
   setClientHeight: (@clientHeight) ->
     @updateLinesState()
 
+  setClientWidth: (@clientWidth) ->
+    @updateLinesState()
+
   setLineHeight: (@lineHeight) ->
     @updateLinesState()
+
+  setBaseCharacterWidth: (@baseCharacterWidth) ->
+    @updateLinesState()