Fix setComposingText when newCursorPosition != 1

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

Index: third_party/WebKit/Source/core/editing/InputMethodController.cpp
diff --git a/third_party/WebKit/Source/core/editing/InputMethodController.cpp b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
index 0d88e0f740a014a088b732b6340f8ca8bef0e15e..fef659aba5f2fa9f134d9a4d440d94d7aca6af3a 100644
--- a/third_party/WebKit/Source/core/editing/InputMethodController.cpp
+++ b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
@@ -239,7 +239,7 @@ void InputMethodController::cancelCompositionIfSelectionIsInvalid()
     frame().chromeClient().didCancelCompositionOnSelectionChange();
 }
 
-void InputMethodController::setComposition(const String& text, const Vector<CompositionUnderline>& underlines, unsigned selectionStart, unsigned selectionEnd)
+void InputMethodController::setComposition(const String& text, const Vector<CompositionUnderline>& underlines, int selectionStart, int selectionEnd)
 {
     Editor::RevealSelectionScope revealSelectionScope(&editor());
 
@@ -332,9 +332,24 @@ void InputMethodController::setComposition(const String& text, const Vector<Comp
     if (baseNode->layoutObject())
         baseNode->layoutObject()->setShouldDoFullPaintInvalidation();
 
-    unsigned start = std::min(baseOffset + selectionStart, extentOffset);
-    unsigned end = std::min(std::max(start, baseOffset + selectionEnd), extentOffset);
-    Range* selectedRange = Range::create(baseNode->document(), baseNode, start, baseNode, end);
+    // In case of exceeding the left boundary.
+    int selectionOffsetsStart = static_cast<int>(getSelectionOffsets().start());
+    int start = std::max(selectionOffsetsStart + selectionStart, 0);
+    int end = std::max(selectionOffsetsStart + selectionEnd, start);
+
+    Element* rootEditableElement = frame().selection().rootEditableElement();
+    if (!rootEditableElement)
+        return;
+
+    // In case of exceeding the right boundary.
+    // If both |value1| and |value2| exceed right boundary,
+    // PlainTextRange(value1, value2)::createRange() will return a default
+    // value, which is [0,0]. In order to get the right boundary in that case,
+    // we should make sure |value1| is within range at least.
+    const EphemeralRange startRange = PlainTextRange(0, start).createRange(*rootEditableElement);

[aelias_OOO_until_Jul13, 2016/05/10 20:44:11]

These ranges are odd, wouldn't it have the same effect to just create two
Position objects instead?

[yabinh, 2016/05/11 00:28:38]

That's right. But in order to create Position objects, we need to know
|anchorNode| and |offset|. And PlainTextRange::createRange() can do that.

[aelias_OOO_until_Jul13, 2016/05/11 02:49:35]

OK, it looks like the algorithm in createRange() isn't split off anywhere else,
I guess it's OK then.  Please store Position objects as local variables instead
of the EphemeralRange to make it clearer that the ranges aren't really of
interest.

[yosin_UTC9, 2016/05/11 05:53:23]

nit: s/const EphemeralRange/const EphemeralRange&/ to avoid redundant copy

+    const EphemeralRange endRange = PlainTextRange(0, end).createRange(*rootEditableElement);

[yosin_UTC9, 2016/05/11 05:53:23]

nit: s/const EphemeralRange/const EphemeralRange&/ to avoid redundant copy

+
+    Range* selectedRange = Range::create(rootEditableElement->document(), startRange.endPosition(), endRange.endPosition());
     frame().selection().setSelectedRange(selectedRange, TextAffinity::Downstream, SelectionDirectionalMode::NonDirectional, NotUserTriggered);
 
     if (underlines.isEmpty()) {