Add isTabStop attribute to Element

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 131 matching lines @@
 }
 
 PassRefPtrWillBeRawPtr<Element> Element::create(const QualifiedName& tagName, Document* document)
 {
     return adoptRefWillBeNoop(new Element(tagName, document, CreateElement));
 }
 
 Element::Element(const QualifiedName& tagName, Document* document, ConstructionType type)
     : ContainerNode(document, type)
     , m_tagName(tagName)
+    , m_isTabStop(true)
 {
 }
 
 Element::~Element()
 {
     ASSERT(needsAttach());
 
 #if !ENABLE(OILPAN)
     if (hasRareData())
         elementRareData()->clearShadow();
@@ skipping 48 matching lines @@
 
 void Element::clearTabIndexExplicitlyIfNeeded()
 {
     if (hasRareData())
         elementRareData()->clearTabIndexExplicitly();
 }
 
 void Element::setTabIndexExplicitly(short tabIndex)
 {
     ensureElementRareData().setTabIndexExplicitly(tabIndex);
+    // isTabStop is overridden by setting tabindex.

[hayato, 2015/02/20 08:46:31]

Not sure how setting taxIndex attribute from JavaScript affects isTabStop
attribute and vice-verse.
What's the intentional behavior?

For example,

A)

element.setAttribute("isTabStop", false);
element.setAttribute("tabIndex", 1);
// What is the expectation of element.isTabStop here?

B)

element.setAttribute("tabIndex", 1);
element.setAttribute("isTabStop", false);
// What is the expectation of element.isTabStop here?

The result of element.isTabStop will differ for A and  B, won't it?
I'm afraid that that might be weird and will be likely to be misused.

[kochi, 2015/02/20 09:43:05]

A) isTabStop = true
B) isTabStop = false

This is because setting tabindex is stronger than isTabStop, for compatibility
reason.
In case A, when you explicitly set isTabStop to false first, but setting
"tabindex=1"
will reset the effect.

I'll add a layout test for these cases.

[hayato, 2015/02/20 10:28:45]

I understand the intention, however, I'm not sure whether it is good or not that
the result of isTabStop depends on the order in which attributes are specified.
Still looks strange to me...

For example (assuming that we cat set both attributes in declarative way):

<div tabindex="1" isTabStop="false">
<div isTabStop="false" tabindex="1">

In these cases, we expect that isTabStop == false in both cases. I expect that
the same thing will happen also in an imperative way.

Is there any way to make it order-independent?

+    m_isTabStop = (tabIndex >= 0);
 }
 
 void Element::setTabIndex(int value)
 {
     setIntegralAttribute(tabindexAttr, value);
 }
 
 short Element::tabIndex() const
 {
     return hasRareData() ? elementRareData()->tabIndex() : 0;
@@ skipping 2013 matching lines @@
 bool Element::isKeyboardFocusable() const
 {
     return isFocusable() && tabIndex() >= 0;
 }
 
 bool Element::isMouseFocusable() const
 {
     return isFocusable();
 }
 
+bool Element::isTabStop() const
+{
+    // Any element which never supports focus will always return false.
+    return supportsFocus() && m_isTabStop;
+}
+
+void Element::setIsTabStop(bool flag)
+{
+    m_isTabStop = flag;
+}
+
 void Element::dispatchFocusEvent(Element* oldFocusedElement, WebFocusType type)
 {
     RefPtrWillBeRawPtr<FocusEvent> event = FocusEvent::create(EventTypeNames::focus, false, false, document().domWindow(), 0, oldFocusedElement);
     EventDispatcher::dispatchEvent(*this, FocusEventDispatchMediator::create(event.release()));
 }
 
 void Element::dispatchBlurEvent(Element* newFocusedElement)
 {
     RefPtrWillBeRawPtr<FocusEvent> event = FocusEvent::create(EventTypeNames::blur, false, false, document().domWindow(), 0, newFocusedElement);
     EventDispatcher::dispatchEvent(*this, BlurEventDispatchMediator::create(event.release()));
@@ skipping 1107 matching lines @@
 {
 #if ENABLE(OILPAN)
     if (hasRareData())
         visitor->trace(elementRareData());
     visitor->trace(m_elementData);
 #endif
     ContainerNode::trace(visitor);
 }
 
 } // namespace blink