Take double width chars into account when soft wrapping

src/display-buffer.coffee

@@ -195,6 +195,12 @@ class DisplayBuffer extends Model
       @defaultCharWidth = defaultCharWidth
     defaultCharWidth
 
+  getDoubleWidthCharWidth: -> @doubleWidthCharWidth
+  setDoubleWidthCharWidth: (doubleWidthCharWidth) ->
+    if doubleWidthCharWidth isnt @doubleWidthCharWidth
+      @doubleWidthCharWidth = doubleWidthCharWidth
+    doubleWidthCharWidth
+
   getCursorWidth: -> 1
 
   scrollToScreenRange: (screenRange, options = {}) ->
@@ -282,8 +288,13 @@ class DisplayBuffer extends Model
         else
           charLength = 1
 
-        charWidth = @getDefaultCharWidth()
+        if iterator.hasDoubleWidthCharacterAt(textIndex)
+          charWidth = @getDoubleWidthCharWidth()
+        else
+          charWidth = @getDefaultCharWidth()
+
         return column if currentWidth + charWidth > lineMaxWidth
+
         currentWidth += charWidth
         column += charLength
         textIndex += charLength

src/token-iterator.coffee

@@ -1,4 +1,5 @@
 {SoftTab, HardTab, PairedCharacter, SoftWrapIndent} = require './special-token-symbols'
+{isDoubleWidthCharacter} = require './text-utils'
 
 module.exports =
 class TokenIterator
@@ -82,5 +83,8 @@ class TokenIterator
   isPairedCharacter: ->
     @line.specialTokens[@index] is PairedCharacter
 
+  hasDoubleWidthCharacterAt: (charIndex) ->
+    isDoubleWidthCharacter(@getText()[charIndex])
+
   isAtomic: ->
     @isSoftTab() or @isHardTab() or @isSoftWrapIndentation() or @isPairedCharacter()