Merge pull request #1799 from atom/cj-calculate-invisibles-correctly

Calculate invisibles correctly

spec/editor-view-spec.coffee

@@ -2894,6 +2894,20 @@ describe "EditorView", ->
       for rowNumber in [1..5]
         expect(editorView.lineElementForScreenRow(rowNumber).text()).toBe buffer.lineForRow(rowNumber)
 
+    it "correctly calculates the position left for non-monospaced invisibles", ->
+      editorView.setShowInvisibles(true)
+      editorView.setInvisibles tab: '♘'
+      editor.setText('\tx')
+
+      editorView.setFontFamily('serif')
+      editorView.setFontSize(10)
+      editorView.attachToDom()
+      editorView.setWidthInChars(5)
+
+      expect(editorView.pixelPositionForScreenPosition([0, 0]).left).toEqual 0
+      expect(editorView.pixelPositionForScreenPosition([0, 1]).left).toEqual 10
+      expect(editorView.pixelPositionForScreenPosition([0, 2]).left).toEqual 13
+
   describe "when the window is resized", ->
     it "updates the active edit session with the current soft wrap column", ->
       editorView.attachToDom()

src/editor-view.coffee

@@ -1338,14 +1338,17 @@ class EditorView extends View
     return 0 if screenColumn == 0
 
     tokenizedLine = @editor.displayBuffer.lineForRow(screenRow)
+    textContent = lineElement.textContent
 
     left = 0
     index = 0
     for token in tokenizedLine.tokens
-      for char in token.value
+      for bufferChar in token.value
         return left if index >= screenColumn
 
-        val = @getCharacterWidthCache(token.scopes, char)
+        # Invisibles might cause renderedChar to be different than bufferChar
+        renderedChar = textContent[index]
+        val = @getCharacterWidthCache(token.scopes, renderedChar)
         if val?
           left += val
         else