Implement select listbox using shadow DOM

Source/core/html/HTMLOptGroupElement.cpp

Index: Source/core/html/HTMLOptGroupElement.cpp
diff --git a/Source/core/html/HTMLOptGroupElement.cpp b/Source/core/html/HTMLOptGroupElement.cpp
index 01c307a46d66dcaa577f3d43c47493147b70485d..1a169294ce24bb4e9220effd5a5d222b5f000c4d 100644
--- a/Source/core/html/HTMLOptGroupElement.cpp
+++ b/Source/core/html/HTMLOptGroupElement.cpp
@@ -28,13 +28,78 @@
 #include "core/HTMLNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/NodeRenderStyle.h"
+#include "core/dom/Text.h"
+#include "core/html/HTMLContentElement.h"
+#include "core/html/HTMLDivElement.h"
 #include "core/html/HTMLSelectElement.h"
 #include "wtf/StdLibExtras.h"
+#include "wtf/unicode/CharacterNames.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
+class GroupLabelElement : public HTMLDivElement {
+public:
+    static PassRefPtrWillBeRawPtr<GroupLabelElement> create(Document&);
+
+    void setText(const String& text)
+    {
+        DEFINE_STATIC_LOCAL(String, nonBreakingSpaceString, (&noBreakSpace, 1));
+        const String& labelText = text.isEmpty() ? nonBreakingSpaceString : text;
+        if (!m_textNode) {
+            m_textNode = Text::create(document(), labelText);
+            appendChild(m_textNode);
+        } else {
+            m_textNode->replaceWholeText(labelText);
+        }
+    }
+
+private:
+    explicit GroupLabelElement(Document& document)
+        : HTMLDivElement(document)
+        , m_textNode(nullptr)
+    {
+        setHasCustomStyleCallbacks();
+    }
+    virtual PassRefPtr<RenderStyle> customStyleForRenderer() OVERRIDE;
+
+    RefPtrWillBeMember<Text> m_textNode;
+};
+
+PassRefPtrWillBeRawPtr<GroupLabelElement> GroupLabelElement::create(Document& document)
+{
+    return adoptRefWillBeNoop(new GroupLabelElement(document));
+}
+
+PassRefPtr<RenderStyle> GroupLabelElement::customStyleForRenderer()
+{
+    RefPtr<RenderStyle> originalStyle = document().styleResolver()->styleForElement(this);
+    RefPtr<RenderStyle> style = RenderStyle::clone(originalStyle.get());
+
+    style->setPaddingRight(Length(2, Fixed));
+    style->setPaddingLeft(Length(2, Fixed));
+
+    int paddingBottom = 1;
+    HTMLSelectElement* selectElement = toHTMLOptGroupElement(shadowHost())->ownerSelectElement();
+    if (selectElement) {
+        const WillBeHeapVector<RawPtrWillBeMember<HTMLElement> >& items = selectElement->listItems();
+        ASSERT(items.size() > 0);
+        if (items.last() == this)
+            paddingBottom = 0;
+    }
+    style->setPaddingBottom(Length(paddingBottom, Fixed));
+
+    return style.release();
+}
+
+PassRefPtrWillBeRawPtr<HTMLOptGroupElement> HTMLOptGroupElement::create(Document& document)
+{
+    RefPtrWillBeRawPtr<HTMLOptGroupElement> optGroupElement = adoptRefWillBeNoop(new HTMLOptGroupElement(document));
+    optGroupElement->ensureUserAgentShadowRoot();
+    return optGroupElement.release();
+}
+
 inline HTMLOptGroupElement::HTMLOptGroupElement(Document& document)
     : HTMLElement(optgroupTag, document)
 {
@@ -42,7 +107,11 @@ inline HTMLOptGroupElement::HTMLOptGroupElement(Document& document)
     ScriptWrappable::init(this);
 }
 
-DEFINE_NODE_FACTORY(HTMLOptGroupElement)
+void HTMLOptGroupElement::trace(Visitor* visitor)
+{
+    visitor->trace(m_groupLabelElement);
+    HTMLElement::trace(visitor);
+}
 
 bool HTMLOptGroupElement::isDisabledFormControl() const
 {
@@ -51,8 +120,11 @@ bool HTMLOptGroupElement::isDisabledFormControl() const
 
 bool HTMLOptGroupElement::rendererIsFocusable() const
 {
-    // Optgroup elements do not have a renderer so we check the renderStyle instead.
-    return renderStyle() && renderStyle()->display() != NONE;
+    HTMLSelectElement* selectElement = ownerSelectElement();
+    if (!selectElement || selectElement->usesMenuList()) {
+        return !isDisplayNone();
+    }
+    return HTMLElement::rendererIsFocusable();
 }
 
 void HTMLOptGroupElement::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
@@ -61,6 +133,12 @@ void HTMLOptGroupElement::childrenChanged(bool changedByParser, Node* beforeChan
     HTMLElement::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
 }
 
+bool HTMLOptGroupElement::rendererIsNeeded(const RenderStyle&)
+{
+    HTMLSelectElement* select = ownerSelectElement();
+    return select && !select->usesMenuList() && !isDisplayNone();
+}
+
 void HTMLOptGroupElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     HTMLElement::parseAttribute(name, value);
@@ -68,6 +146,8 @@ void HTMLOptGroupElement::parseAttribute(const QualifiedName& name, const Atomic
 
     if (name == disabledAttr)
         didAffectSelector(AffectedSelectorDisabled | AffectedSelectorEnabled);
+    else if (name == labelAttr)
+        updateGroupLabel();
 }
 
 void HTMLOptGroupElement::recalcSelectOptions()
@@ -112,6 +192,7 @@ PassRefPtr<RenderStyle> HTMLOptGroupElement::customStyleForRenderer()
     return m_style;
 }
 
+
 String HTMLOptGroupElement::groupLabelText() const
 {
     String itemText = getAttribute(labelAttr);
@@ -124,6 +205,16 @@ String HTMLOptGroupElement::groupLabelText() const
     return itemText;
 }
 
+LayoutUnit HTMLOptGroupElement::groupLabelHeight() const
+{
+    if (!m_groupLabelElement)
+        return 0;
+    RenderObject* labelRenderer = m_groupLabelElement->renderer();
+    if (!labelRenderer)
+        return 0;
+    return labelRenderer->absoluteBoundingBoxRect().height();
+}
+
 HTMLSelectElement* HTMLOptGroupElement::ownerSelectElement() const
 {
     return Traversal<HTMLSelectElement>::firstAncestor(*this);
@@ -137,10 +228,47 @@ void HTMLOptGroupElement::accessKeyAction(bool)
         select->accessKeyAction(false);
 }
 
+void HTMLOptGroupElement::didAddUserAgentShadowRoot(ShadowRoot& root)
+{
+    RefPtr<GroupLabelElement> groupLabelElement = GroupLabelElement::create(document());
+    groupLabelElement->setText(String());
+    root.appendChild(groupLabelElement);
+    m_groupLabelElement = groupLabelElement.get();
+
+    RefPtr<HTMLContentElement> content = HTMLContentElement::create(document());
+    content->setAttribute(selectAttr, "option");
+    root.appendChild(content);
+}
+
+void HTMLOptGroupElement::updateGroupLabel()
+{
+    static_cast<GroupLabelElement*>(ensureUserAgentShadowRoot().firstChild())->setText(groupLabelText());
+}
+
 bool HTMLOptGroupElement::isDisplayNone() const
 {
-    RenderStyle* style = nonRendererStyle();
-    return style && style->display() == NONE;
+    RenderStyle* style = renderStyle();
+    return !style || style->display() == NONE;
+}
+
+Node::InsertionNotificationRequest HTMLOptGroupElement::insertedInto(ContainerNode* insertionPoint)
+{
+    HTMLElement::insertedInto(insertionPoint);
+    return insertionPoint->inDocument() ? InsertionShouldCallDidNotifySubtreeInsertions : InsertionDone;
+}
+
+void HTMLOptGroupElement::didNotifySubtreeInsertionsToDocument()
+{
+    updateView();
+}
+
+void HTMLOptGroupElement::updateView()
+{
+    HTMLSelectElement* select = ownerSelectElement();
+    if (select && !select->usesMenuList())
+        ensureUserAgentShadowRoot();
+    else if (userAgentShadowRoot())
+        userAgentShadowRoot()->detach();
 }
 
 } // namespace