From c2ee942df14b4863cb49c6f28f34bef49d39d127 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 15 Oct 2015 16:24:08 +0200
Subject: [PATCH] Take double width chars into account when soft wrapping

---
 spec/display-buffer-spec.coffee | 10 ++++++++++
 src/display-buffer.coffee       | 13 ++++++++++++-
 src/token-iterator.coffee       |  4 ++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/spec/display-buffer-spec.coffee b/spec/display-buffer-spec.coffee
index a6b6242d4..69d78bf70 100644
--- a/spec/display-buffer-spec.coffee
+++ b/spec/display-buffer-spec.coffee
@@ -60,6 +60,16 @@ describe "DisplayBuffer", ->
       changeHandler.reset()
 
     describe "rendering of soft-wrapped lines", ->
+      describe "when there are double width characters", ->
+        it "takes them into account when finding the soft wrap column", ->
+          displayBuffer.setDoubleWidthCharWidth(5)
+          buffer.setText("私たちのフ是一个地方，数千名学生12345业余爱们的板作为우리포럼hello world this is a pretty long latin line")
+
+          expect(displayBuffer.tokenizedLineForScreenRow(0).text).toBe("私たちのフ是一个地方")
+          expect(displayBuffer.tokenizedLineForScreenRow(1).text).toBe("，数千名学生12345业余爱")
+          expect(displayBuffer.tokenizedLineForScreenRow(2).text).toBe("们的板作为우리포럼hello ")
+          expect(displayBuffer.tokenizedLineForScreenRow(3).text).toBe("world this is a pretty long latin line")
+
       describe "when editor.softWrapAtPreferredLineLength is set", ->
         it "uses the preferred line length as the soft wrap column when it is less than the configured soft wrap column", ->
           atom.config.set('editor.preferredLineLength', 100)
diff --git a/src/display-buffer.coffee b/src/display-buffer.coffee
index a545235c2..948101385 100644
--- a/src/display-buffer.coffee
+++ b/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
diff --git a/src/token-iterator.coffee b/src/token-iterator.coffee
index de874d499..4c4686635 100644
--- a/src/token-iterator.coffee
+++ b/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()