Fix InputConnection.deleteSurroundingText()

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 0bd3b86d91b2380d6a7380e89bc63feae01cc7e0..da90163bcb938013076bc6d06deb593c842c1506 100644
--- a/third_party/WebKit/Source/core/editing/InputMethodController.cpp
+++ b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
@@ -548,6 +548,85 @@ void InputMethodController::extendSelectionAndDelete(int before, int after)
     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;
+    Element* rootEditableElement = frame().selection().rootEditableElement();
+    if (!rootEditableElement)
+        return;
+
+    size_t selectionStart = selectionOffsets.start();
+    size_t selectionEnd = selectionOffsets.end();
+
+    if (before > 0u && selectionStart > 0u) {
+        // In case of exceeding the left boundary.
+        int start = std::max(static_cast<int>(selectionStart) - static_cast<int>(before), 0);
+
+        if (rootEditableElement->innerText()[start] != '\n') {
+            // 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.
+            const EphemeralRange range = PlainTextRange(start, start + 1).createRange(*rootEditableElement);
+            if (range.isNull())
+                return;
+
+            Position position = range.startPosition();
+            Position nextPosition = range.endPosition();
+            Position adjustedPosition = previousPositionOf(nextPosition, PositionMoveType::GraphemeCluster);
+
+            int diff = adjustedPosition.computeOffsetInContainerNode() - position.computeOffsetInContainerNode();
+            start = start + diff;
+        }
+
+        if (!setSelectionOffsets(PlainTextRange(start, static_cast<int>(selectionStart))))
+            return;
+        TypingCommand::deleteSelection(*frame().document());
+
+        selectionEnd = selectionEnd - (selectionStart - start);
+        selectionStart = start;
+    }
+
+    if (after > 0u) {
+        // Adjust the deleted range in case of exceeding the right boundary.
+        PlainTextRange deletionRange(static_cast<int>(selectionEnd), static_cast<int>(selectionEnd + after));
+        if (deletionRange.isNull())
+            return;
+        const EphemeralRange validRange = deletionRange.createRange(*rootEditableElement);
+        if (validRange.isNull())
+            return;
+        PlainTextRange validDeletionRange = PlainTextRange::create(*rootEditableElement, validRange);
+        if (validDeletionRange.isNull())
+            return;
+        int end = validDeletionRange.end();
+
+        if (rootEditableElement->innerText()[end - 1] != '\n') {
+            // We also need to adjust the end of selection for multi-code text.
+            const EphemeralRange range = PlainTextRange(end - 1, end).createRange(*rootEditableElement);
+            if (range.isNull())
+                return;
+
+            Position position = range.endPosition();
+            Position previousPosition = range.startPosition();
+            Position adjustedPosition = nextPositionOf(previousPosition, PositionMoveType::GraphemeCluster);
+
+            int diff = adjustedPosition.computeOffsetInContainerNode() - position.computeOffsetInContainerNode();
+            end = end + diff;
+        }
+
+        if (!setSelectionOffsets(PlainTextRange(static_cast<int>(selectionEnd), end)))
+            return;
+        TypingCommand::deleteSelection(*frame().document());
+    }
+
+    setSelectionOffsets(PlainTextRange(selectionStart, selectionEnd));
+}
+
 DEFINE_TRACE(InputMethodController)
 {
     visitor->trace(m_frame);