Get rid of redundant layout tree update related to selection

third_party/WebKit/Source/core/html/TextControlElement.cpp

Index: third_party/WebKit/Source/core/html/TextControlElement.cpp
diff --git a/third_party/WebKit/Source/core/html/TextControlElement.cpp b/third_party/WebKit/Source/core/html/TextControlElement.cpp
index f214cb1c8bbad618e27afd92b3b4c8f2a899c06d..8669007430f601925ca7f2572051adad2a1e0d76 100644
--- a/third_party/WebKit/Source/core/html/TextControlElement.cpp
+++ b/third_party/WebKit/Source/core/html/TextControlElement.cpp
@@ -485,9 +485,16 @@ unsigned TextControlElement::selectionStart() const {
 
 unsigned TextControlElement::computeSelectionStart() const {
   DCHECK(isTextControl());
-  if (LocalFrame* frame = document().frame())
-    return indexForPosition(innerEditorElement(), frame->selection().start());
-  return 0;
+  LocalFrame* frame = document().frame();
+  if (!frame)
+    return 0;
+  const SelectionInDOMTree& selection = frame->selection().selectionInDOMTree();
+  if (selection.granularity() == CharacterGranularity) {

[yoichio, 2017/02/17 04:35:16]

Why do you split case on granularity?

[yosin_UTC9, 2017/02/17 05:14:49]

I introduce SelectionTemplate::computeSelectionTypeConsideringGranularity().
So, this code will look more simpler.

In current implementation, if granularity is other than character, m_base ==
m_extent.
We need to handle this case.

+    return indexForPosition(innerEditorElement(),
+                            selection.computeStartPosition());
+  }
+  const VisibleSelection& visibleSelection = frame->selection().selection();
+  return indexForPosition(innerEditorElement(), visibleSelection.start());
 }
 
 unsigned TextControlElement::selectionEnd() const {
@@ -500,9 +507,16 @@ unsigned TextControlElement::selectionEnd() const {
 
 unsigned TextControlElement::computeSelectionEnd() const {
   DCHECK(isTextControl());
-  if (LocalFrame* frame = document().frame())
-    return indexForPosition(innerEditorElement(), frame->selection().end());
-  return 0;
+  LocalFrame* frame = document().frame();
+  if (!frame)
+    return 0;
+  const SelectionInDOMTree& selection = frame->selection().selectionInDOMTree();
+  if (selection.granularity() == CharacterGranularity) {
+    return indexForPosition(innerEditorElement(),
+                            selection.computeEndPosition());
+  }
+  const VisibleSelection& visibleSelection = frame->selection().selection();
+  return indexForPosition(innerEditorElement(), visibleSelection.end());
 }
 
 static const AtomicString& directionString(
@@ -539,10 +553,11 @@ TextFieldSelectionDirection TextControlElement::computeSelectionDirection()
   if (!frame)
     return SelectionHasNoDirection;
 
-  const VisibleSelection& selection = frame->selection().selection();
+  const SelectionInDOMTree& selection = frame->selection().selectionInDOMTree();
+  const Position& start = selection.computeStartPosition();
   return selection.isDirectional()
-             ? (selection.isBaseFirst() ? SelectionHasForwardDirection
-                                        : SelectionHasBackwardDirection)
+             ? (selection.base() == start ? SelectionHasForwardDirection
+                                          : SelectionHasBackwardDirection)
              : SelectionHasNoDirection;
 }
 
@@ -685,10 +700,15 @@ void TextControlElement::selectionChanged(bool userTriggered) {
   cacheSelection(computeSelectionStart(), computeSelectionEnd(),
                  computeSelectionDirection());
 
-  if (LocalFrame* frame = document().frame()) {
-    if (frame->selection().isRange() && userTriggered)
-      dispatchEvent(Event::createBubble(EventTypeNames::select));
-  }
+  LocalFrame* frame = document().frame();
+  if (!frame || !userTriggered)
+    return;
+  const SelectionInDOMTree& selection = frame->selection().selectionInDOMTree();
+  if (selection.isNone())
+    return;
+  if (selection.isCaret() && selection.granularity() == CharacterGranularity)
+    return;
+  dispatchEvent(Event::createBubble(EventTypeNames::select));
 }
 
 void TextControlElement::scheduleSelectEvent() {