Fix InputConnection.deleteSurroundingText()

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 667 matching lines @@
   } while (frame().selection().start() == frame().selection().end() &&
            before <= static_cast<int>(selectionOffsets.start()));
   // TODO(chongz): Find a way to distinguish Forward and Backward.
   dispatchBeforeInputEditorCommand(
       m_frame->document()->focusedElement(),
       InputEvent::InputType::DeleteContentBackward,
       new RangeVector(1, m_frame->selection().firstRange()));
   TypingCommand::deleteSelection(*frame().document());
 }
 
+// TODO(yabinh): We should reduce the number of selectionchange events.
+void InputMethodController::deleteSurroundingText(int before, int after) {
+  if (!editor().canEdit())
+    return;
+  PlainTextRange selectionOffsets(getSelectionOffsets());
+  if (selectionOffsets.isNull())
+    return;
+  Element* rootEditableElement = frame().selection().rootEditableElement();
+  if (!rootEditableElement)
+    return;
+
+  int selectionStart = static_cast<int>(selectionOffsets.start());
+  int selectionEnd = static_cast<int>(selectionOffsets.end());
+
+  if (before > 0 && selectionStart > 0) {
+    // In case of exceeding the left boundary.
+    int start = std::max(selectionStart - before, 0);
+
+    // Select the text to be deleted before selectionStart.
+    // We should adjust the start of selection for multi-code text(a grapheme
+    // cluster contains more than one code point).
+    const EphemeralRange& range =
+        PlainTextRange(0, start).createRange(*rootEditableElement);
+    if (range.isNull())
+      return;
+    const Position& position = range.endPosition();
+    // TODO(yabinh): Deletion should be based on code point instead of grapheme
+    // cluster.
+    const Position& adjustedPosition = previousPositionOf(

[yosin_UTC9, 2016/10/12 08:34:17]

I saw this pattern in another CL. Can we have functions to compute diff for both
previous/next?

[yabinh, 2016/10/13 01:44:33]

Done.

+        nextPositionOf(position, PositionMoveType::GraphemeCluster),
+        PositionMoveType::GraphemeCluster);
+    DCHECK_EQ(position.anchorNode(), adjustedPosition.anchorNode());
+    DCHECK_LE(adjustedPosition.computeOffsetInContainerNode(),
+              position.computeOffsetInContainerNode());
+    const int diff = adjustedPosition.computeOffsetInContainerNode() -
+                     position.computeOffsetInContainerNode();
+    start = start + diff;

[yosin_UTC9, 2016/10/12 08:34:17]

Let's introduce new variable, e.g. |adjustedStart|.

[yabinh, 2016/10/13 01:44:33]

Done.

+
+    if (!setSelectionOffsets(PlainTextRange(start, selectionStart)))
+      return;
+    TypingCommand::deleteSelection(*frame().document());
+
+    selectionEnd = selectionEnd - (selectionStart - start);
+    selectionStart = start;
+  }
+
+  if (after > 0) {
+    // Adjust the deleted range in case of exceeding the right boundary.
+    PlainTextRange range(0, selectionEnd + after);
+    if (range.isNull())
+      return;
+    const EphemeralRange& validRange = range.createRange(*rootEditableElement);
+    if (validRange.isNull())
+      return;
+    int end = PlainTextRange::create(*rootEditableElement, validRange).end();
+
+    // We also need to adjust the end of selection for multi-code text.
+    const Position& position = validRange.endPosition();
+    const Position& adjustedPosition = nextPositionOf(
+        previousPositionOf(position, PositionMoveType::GraphemeCluster),
+        PositionMoveType::GraphemeCluster);
+    DCHECK_EQ(position.anchorNode(), adjustedPosition.anchorNode());
+    DCHECK_GE(adjustedPosition.computeOffsetInContainerNode(),
+              position.computeOffsetInContainerNode());
+    const int diff = adjustedPosition.computeOffsetInContainerNode() -
+                     position.computeOffsetInContainerNode();
+    end = end + diff;

[yosin_UTC9, 2016/10/12 08:34:17]

Let's introduce new variable, e.g. |adjustedEnd|.

[yabinh, 2016/10/13 01:44:33]

Done.

+
+    if (!setSelectionOffsets(PlainTextRange(selectionEnd, end)))
+      return;
+    TypingCommand::deleteSelection(*frame().document());
+  }
+
+  setSelectionOffsets(PlainTextRange(selectionStart, selectionEnd));
+}
+
 DEFINE_TRACE(InputMethodController) {
   visitor->trace(m_frame);
   visitor->trace(m_compositionRange);
 }
 
 }  // namespace blink