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 454 matching lines @@
             return;
         if (before == 0)
             break;
         ++before;
     } while (frame().selection().start() == frame().selection().end() && before <= static_cast<int>(selectionOffsets.start()));
     // TODO(chongz): According to spec |data| should be "forward" or "backward".
     dispatchBeforeInputEditorCommand(frame().document()->focusedElement(), InputEvent::InputType::DeleteContent);
     TypingCommand::deleteSelection(*frame().document());
 }
 
+void InputMethodController::deleteSurroundingText(int before, int after)
+{
+    if (!editor().canEdit())
+        return;
+    PlainTextRange selectionOffsets(getSelectionOffsets());
+    if (selectionOffsets.isNull())
+        return;
+
+    int selectionStart = static_cast<int>(selectionOffsets.start());
+    int selectionEnd = static_cast<int>(selectionOffsets.end());
+
+    // Some multi-code-texts take 2 positions, like "\xF0\x9F\x8F\x86"(U+1F3C6
+    // =="trophy"). We can select the whole multi-code-text successfully if we
+    // only select the left half of it, but we can't select it if we only select
+    // the right half of it. For the latter case, we need to select more.
+    if (before > 0) {
+        int deleteLength, leftStart, leftEnd;
+        int adjustedBefore = before;
+        do {
+            deleteLength = std::min(selectionStart, adjustedBefore);
+            leftStart = selectionStart - deleteLength;
+            leftEnd = selectionStart;
+            if (!setSelectionOffsets(PlainTextRange(leftStart, leftEnd)))
+                return;
+            ++adjustedBefore;
+        } while (frame().selection().start().computeOffsetInContainerNode() + before > frame().selection().end().computeOffsetInContainerNode() && before <= static_cast<int>(selectionOffsets.start()));

[Changwan Ryu, 2016/04/22 02:16:09]

1) while condition is too long, and the latter condition is true throughout the
loop.
2) too many variables.
3) comment belongs to inside the if statement.

I just tried to simplify it as follows:

if (before > 0) {
    before = std::min(selectionStart, before);

    // Select the text to be deleted before selectionStart,
    // and adjust 'before' in case of multi-code text.
    for (; before <= selectionStart; ++before) {
        if (!setSelectionOffsets(PlainTextRange(selectionStart - before,
selectionStart)))
            return;
        if (frame().selection.start().computeOffsetInContainerNode() + before <=
frame().selection().end().computeOffsetInContainerNode())
            break;
    }
    CHECK_LE(before, selectionStart);

    TypingCommand::deleteSelection(*frame().document());

    selectionStart = selectionStart - before;
    selectionEnd = selectionEnd - before;
}

WDYT?

[yabinh, 2016/04/22 02:51:53]

You are right. It'll be more simple.

+        TypingCommand::deleteSelection(*frame().document());
+
+        selectionStart = leftStart;
+        selectionEnd = selectionEnd - deleteLength;
+    }
+
+    if (after > 0) {
+        int rightStart = selectionEnd;
+        int rightEnd = selectionEnd + after;
+        if (!setSelectionOffsets(PlainTextRange(rightStart, rightEnd)))
+            return;
+        TypingCommand::deleteSelection(*frame().document());
+    }
+
+    setSelectionOffsets(PlainTextRange(selectionStart, selectionEnd));
+}
+
 DEFINE_TRACE(InputMethodController)
 {
     visitor->trace(m_frame);
     visitor->trace(m_compositionRange);
 }
 
 } // namespace blink