Fix setComposingText when newCursorPosition != 1

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 221 matching lines @@
     if (!selection.isNone() && !m_compositionRange->collapsed()) {
         if (selection.start().compareTo(m_compositionRange->startPosition()) >= 0
             && selection.end().compareTo(m_compositionRange->endPosition()) <= 0)
             return;
     }
 
     cancelComposition();
     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());
 
     // Updates styles before setting selection for composition to prevent
     // inserting the previous composition text into text nodes oddly.
     // See https://bugs.webkit.org/show_bug.cgi?id=46868
     frame().document()->updateLayoutTree();
 
     selectComposition();
 
@@ skipping 72 matching lines @@
     m_isDirty = true;
     m_hasComposition = true;
     if (!m_compositionRange)
         m_compositionRange = Range::create(baseNode->document());
     m_compositionRange->setStart(baseNode, baseOffset);
     m_compositionRange->setEnd(baseNode, extentOffset);
 
     if (baseNode->layoutObject())
         baseNode->layoutObject()->setShouldDoFullPaintInvalidation();
 
-    unsigned start = std::min(baseOffset + selectionStart, extentOffset);
-    unsigned end = std::min(std::max(start, baseOffset + selectionEnd), extentOffset);
+    // In case of exceeding the left boundary.
+    int start = std::max(static_cast<int>(baseOffset) + selectionStart, 0);
+    int end = std::max(static_cast<int>(baseOffset) + selectionEnd, start);
+
+    // In case of exceeding the right boundary.
+    const EphemeralRange textRange = PlainTextRange(0, end).createRange(*(baseNode->parentElement()));
+    int textEnd = textRange.endPosition().computeOffsetInContainerNode();

[Changwan Ryu, 2016/05/02 06:49:00]

How about simply the following?

int textEnd = Position::lastOffsetForEditing(baseNode);

[yabinh, 2016/05/02 09:48:10]

Do you mean:
int textEnd = EditingStrategy::lastOffsetForEditing(baseNode);

It can't work correctly for multiple nodes, because textEnd is the length of
text in the current node, not the length of the whole text.

[Changwan Ryu, 2016/05/02 10:51:49]

Ok, I couldn't find a better solution here. But calling parentElement() doesn't
seem right.
Could you add the following test cases?
1) baseNode is two levels below the contenteditable, such that
baseNode->parentElement() can fail.
2) Adding selectionStart ends up in a node other than the currently
selected/composited node (such that lastOffsetForEditing() can fail)

+    start = std::min(start, textEnd);
+    end = std::min(end, textEnd);
+
     Range* selectedRange = Range::create(baseNode->document(), baseNode, start, baseNode, end);
     frame().selection().setSelectedRange(selectedRange, TextAffinity::Downstream, SelectionDirectionalMode::NonDirectional, NotUserTriggered);
 
     if (underlines.isEmpty()) {
         frame().document()->markers().addCompositionMarker(m_compositionRange->startPosition(), m_compositionRange->endPosition(), Color::black, false, LayoutTheme::theme().platformDefaultCompositionBackgroundColor());
         return;
     }
     for (const auto& underline : underlines) {
         unsigned underlineStart = baseOffset + underline.startOffset;
         unsigned underlineEnd = baseOffset + underline.endOffset;
@@ skipping 121 matching lines @@
     TypingCommand::deleteSelection(*frame().document());
 }
 
 DEFINE_TRACE(InputMethodController)
 {
     visitor->trace(m_frame);
     visitor->trace(m_compositionRange);
 }
 
 } // namespace blink