Fix setComposingText when newCursorPosition != 1

third_party/WebKit/Source/core/editing/PlainTextRange.cpp

Index: third_party/WebKit/Source/core/editing/PlainTextRange.cpp
diff --git a/third_party/WebKit/Source/core/editing/PlainTextRange.cpp b/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
index 7cfb84d3ba034f28437dd9c0c45e3f34382c3cb6..d3e19cb91bf84086a49f30bf6fc4851147ff13ad 100644
--- a/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
+++ b/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
@@ -73,7 +73,7 @@ EphemeralRange PlainTextRange::createRangeFor(const ContainerNode& scope, GetRan
     ASSERT(isNotNull());
 
     size_t docTextPosition = 0;
-    bool startRangeFound = false;
+    bool startOutOfBound = true;
 
     Position textRunStartPosition;
     Position textRunEndPosition;
@@ -119,8 +119,9 @@ EphemeralRange PlainTextRange::createRangeFor(const ContainerNode& scope, GetRan
             }
         }
 
-        if (foundStart) {
-            startRangeFound = true;
+        // resultStart should be assigned the first time foundStart is true.

[Changwan Ryu, 2016/04/07 11:46:19]

I don't feel that this comment is needed here.

+        if (foundStart && startOutOfBound) {

[Changwan Ryu, 2016/04/07 11:46:19]

no need to check startOutOfBound?

[yabinh, 2016/04/08 01:21:30]

In "foundStart = start() >= docTextPosition && start() <= docTextPosition +
len", there is a "=". It means that foundStart can be true for 2 times in the
loop. But resultStart is assigned correctly only in the first time.

For example, if there are 3 nodes:"hello","\n","world!", and we want to move the
cursor to 5, like:
hello*
world!
where * stands for cursor.
 
foundstart will be true both in the first node(because start()==0,
docTextPosition==0, len==5, and 0 <= 0 <=5) and in the second node(because
start()==5, docTextPosition==5, len==1, and 5 <= 5 <=6). If resultStart is
assigned in the second time, the cursor will be like this:
hello
*world!
which is not correct.

[yabinh, 2016/04/11 05:53:25]

I was wrong about it. I thought the selected range was wrong, and I should
change it. But it turned out that although the selected range was wrong, it was
changed in SelectionEditor::setSelectedRange. So there is no need to change it
in advance. 

And also, it shouldn’t be changed twice, because it will cause some problems for
certain boundary cases.

Anyway, no need to change “if(foundStart)”.

+            startOutOfBound = false;
             if (textRunStartPosition.computeContainerNode()->isTextNode()) {
                 int offset = start() - docTextPosition;
                 resultStart = Position(textRunStartPosition.computeContainerNode(), offset + textRunStartPosition.offsetInContainerNode());
@@ -148,8 +149,10 @@ EphemeralRange PlainTextRange::createRangeFor(const ContainerNode& scope, GetRan
         docTextPosition += len;
     }
 
-    if (!startRangeFound)
-        return EphemeralRange();
+    if (startOutOfBound) {
+        resultStart = textRunEndPosition;
+        resultEnd = textRunEndPosition;
+    }
 
     if (length() && end() > docTextPosition) { // end() is out of bounds
         resultEnd = textRunEndPosition;