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 530 matching lines @@
         if (before == 0)
             break;
         ++before;
     } while (frame().selection().start() == frame().selection().end() && before <= static_cast<int>(selectionOffsets.start()));
     // TODO(chongz): New spec might want to change InputType.
     // https://github.com/w3c/editing/issues/125#issuecomment-213041256
     dispatchBeforeInputEditorCommand(m_frame->document()->focusedElement(), InputEvent::InputType::DeleteContent, emptyString(), new RangeVector(1, m_frame->selection().firstRange()));
     TypingCommand::deleteSelection(*frame().document());
 }
 
+// TODO(yabinh): We should reduce the number of selectionchange events.
+void InputMethodController::deleteSurroundingText(size_t before, size_t after)
+{
+    if (!editor().canEdit())
+        return;
+    PlainTextRange selectionOffsets(getSelectionOffsets());
+    if (selectionOffsets.isNull())
+        return;
+
+    size_t selectionStart = selectionOffsets.start();
+    size_t selectionEnd = selectionOffsets.end();
+
+    if (before > 0u && selectionStart > 0u) {
+        // In case of exceeding the left boundary.
+        before = std::min(selectionStart, before);
+
+        // Select the text to be deleted before selectionStart.
+        // For multi-code text, we can't select it successfully if we only
+        // select the right half of it. So we need to adjust the start of
+        // selection.
+        Position position(frame().selection().start().anchorNode(), selectionStart - before + 1);

[Changwan Ryu, 2016/07/05 15:47:36]

On a second look, I'm concerned about this line. Is the position always valid
for the offset when anchorNode != rootEditableElement? Could you add some more
test cases around such a case?

[yabinh, 2016/07/06 02:15:02]

I think we've already had that case in DeleteSurroundingTextForMultipleNodes.

Let * stand for |position|, and # stand for |adjustedPosition|, then:
hello#\n*world
Notice that for |position|, its anchorNode is the first child node; for
|adjustedPosition|, its anchorNode is the third child node. Their parent node is
rootEditableElement.

[Changwan Ryu, 2016/07/06 04:20:19]

Hmm... I was more worried about the case where before > 1 and that selection's
anchor node is different from deletion start position's anchor node. Adjusted
position is irrelevant in my comment.

+        Position adjustedPosition = previousPositionOf(position, PositionMoveType::GraphemeCluster);
+        int adjustedStart = adjustedPosition.computeOffsetInContainerNode();
+
+        if (!setSelectionOffsets(PlainTextRange(adjustedStart, static_cast<int>(selectionStart))))
+            return;
+        TypingCommand::deleteSelection(*frame().document());
+
+        selectionEnd = selectionEnd - (selectionStart - adjustedStart);
+        selectionStart = adjustedStart;
+    }
+
+    if (after > 0u) {
+        // Adjust the deleted range in case of exceeding the right boundary.
+        PlainTextRange range(static_cast<int>(selectionEnd), static_cast<int>(selectionEnd + after));
+        if (range.isNull())
+            return;
+        Element* rootEditableElement = frame().selection().rootEditableElement();
+        if (!rootEditableElement)
+            return;
+        const EphemeralRange adjustedRange = range.createRange(*rootEditableElement);
+        if (adjustedRange.isNull())
+            return;
+
+        // Select the text to be deleted after selectionEnd.
+        // We also need to adjust the end of selection for multi-code text.
+        Position position(frame().selection().start().anchorNode(), adjustedRange.endPosition().computeOffsetInContainerNode() - 1);
+        Position adjustedPosition = nextPositionOf(position, PositionMoveType::GraphemeCluster);
+        int adjustedEnd = adjustedPosition.computeOffsetInContainerNode();
+
+        if (!setSelectionOffsets(PlainTextRange(static_cast<int>(selectionEnd), adjustedEnd)))
+            return;
+        TypingCommand::deleteSelection(*frame().document());
+    }
+
+    setSelectionOffsets(PlainTextRange(selectionStart, selectionEnd));
+}
+
 DEFINE_TRACE(InputMethodController)
 {
     visitor->trace(m_frame);
     visitor->trace(m_compositionRange);
 }
 
 } // namespace blink