Get rid of redundant layout tree update related to selection

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 382 matching lines @@
       ++index;
     }
   }
 
   return index;
 }
 
 bool TextControlElement::setSelectionRange(
     unsigned start,
     unsigned end,
     TextFieldSelectionDirection direction) {

[yoichio, 2017/02/17 04:18:59]

As offline discussion, we put DocumentLifecycle::DisallowTransitionScope
 here.

   if (openShadowRoot() || !isTextControl())
     return false;
   const unsigned editorValueLength = innerEditorValue().length();
   end = std::min(end, editorValueLength);
   start = std::min(start, end);
   LocalFrame* frame = document().frame();
   if (direction == SelectionHasNoDirection && frame &&
       frame->editor().behavior().shouldConsiderSelectionAsDirectional())
     direction = SelectionHasForwardDirection;
   cacheSelection(start, end, direction);
@@ skipping 64 matching lines @@
   if (!isTextControl())
     return 0;
   if (document().focusedElement() != this)
     return m_cachedSelectionStart;
 
   return computeSelectionStart();
 }
 
 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 {
   if (!isTextControl())
     return 0;
   if (document().focusedElement() != this)
     return m_cachedSelectionEnd;
   return computeSelectionEnd();
 }
 
 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(
     TextFieldSelectionDirection direction) {
   DEFINE_STATIC_LOCAL(const AtomicString, none, ("none"));
   DEFINE_STATIC_LOCAL(const AtomicString, forward, ("forward"));
   DEFINE_STATIC_LOCAL(const AtomicString, backward, ("backward"));
 
   switch (direction) {
     case SelectionHasNoDirection:
@@ skipping 16 matching lines @@
   return directionString(computeSelectionDirection());
 }
 
 TextFieldSelectionDirection TextControlElement::computeSelectionDirection()
     const {
   DCHECK(isTextControl());
   LocalFrame* frame = document().frame();
   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;
 }
 
 static inline void setContainerAndOffsetForRange(Node* node,
                                                  int offset,
                                                  Node*& containerNode,
                                                  int& offsetInContainer) {
   if (node->isTextNode()) {
     containerNode = node;
     offsetInContainer = offset;
@@ skipping 122 matching lines @@
 
 void TextControlElement::selectionChanged(bool userTriggered) {
   if (!layoutObject() || !isTextControl())
     return;
 
   // selectionStart() or selectionEnd() will return cached selection when this
   // node doesn't have focus.
   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() {
   Event* event = Event::createBubble(EventTypeNames::select);
   event->setTarget(this);
   document().enqueueUniqueAnimationFrameEvent(event);
 }
 
 void TextControlElement::parseAttribute(
     const AttributeModificationParams& params) {
@@ skipping 195 matching lines @@
 
 void TextControlElement::copyNonAttributePropertiesFromElement(
     const Element& source) {
   const TextControlElement& sourceElement =
       static_cast<const TextControlElement&>(source);
   m_lastChangeWasUserEdit = sourceElement.m_lastChangeWasUserEdit;
   HTMLFormControlElement::copyNonAttributePropertiesFromElement(source);
 }
 
 }  // namespace blink