Simplify and add caching for accessible bounding box calculation.

Source/core/accessibility/AccessibilityRenderObject.h

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 45 matching lines @@
 class VisibleSelection;
 class Widget;
 
 class AccessibilityRenderObject : public AccessibilityNodeObject {
 protected:
     explicit AccessibilityRenderObject(RenderObject*);
 public:
     static PassRefPtr<AccessibilityRenderObject> create(RenderObject*);
     virtual ~AccessibilityRenderObject();
 
-    RenderObject* m_renderer;
-
     // Public, overridden from AccessibilityObject.
     virtual RenderObject* renderer() const { return m_renderer; }
-    virtual LayoutRect elementRect() const;
+    virtual LayoutRect elementRect();

[Julien - ping for review, 2013/05/03 20:54:20]

FWIW I would have kept this const because you still match the definition of
logical constness (you're only updating your cache). That means making the
caching related members 'mutable'.

[dmazzoni, 2013/05/06 04:58:01]

Great idea, that simplifies things a lot.

 
     // DEPRECATED - investigate and remove.
     virtual int layoutCount() const;
 
     void setRenderer(RenderObject*);
     RenderBoxModelObject* renderBoxModelObject() const;
     RenderView* topRenderer() const;
     Document* topDocument() const;
     HTMLLabelElement* labelElementContainer() const;
     bool shouldNotifyActiveDescendant() const;
     bool needsToUpdateChildren() const { return m_childrenDirty; }
     ScrollableArea* getScrollableAreaIfScrollable() const;
     virtual AccessibilityRole determineAccessibilityRole();
 
 protected:
+    RenderObject* m_renderer;
+    LayoutRect m_cachedElementRect;
+    LayoutRect m_cachedFrameRect;
+    bool m_cachedElementRectDirty;
+
     //
     // Overridden from AccessibilityObject.
     //
 
     virtual void init();
     virtual void detach();
     virtual bool isDetached() const { return !m_renderer; }
     virtual bool isAccessibilityRenderObject() const { return true; }
 
     // Check object role or purpose.
@@ skipping 27 matching lines @@
     // Whether objects are ignored, i.e. not included in the tree.
     virtual AccessibilityObjectInclusion defaultObjectInclusion() const;
     virtual bool computeAccessibilityIsIgnored() const;
 
     // Properties of static elements.
     virtual const AtomicString& accessKey() const;
     virtual AccessibilityObject* correspondingControlForLabelElement() const;
     virtual AccessibilityObject* correspondingLabelForControlElement() const;
     virtual bool exposesTitleUIElement() const;
     virtual void linkedUIElements(AccessibilityChildrenVector&) const;
-    virtual AccessibilityOrientation orientation() const;
+    virtual AccessibilityOrientation orientation();
     virtual void tabChildren(AccessibilityChildrenVector&);
     virtual String text() const;
     virtual int textLength() const;
     virtual AccessibilityObject* titleUIElement() const;
     virtual KURL url() const;
     virtual void visibleChildren(AccessibilityChildrenVector&);
 
     // Properties of interactive elements.
     virtual const String& actionVerb() const;
-    LayoutRect checkboxOrRadioRect() const;
     virtual void selectedChildren(AccessibilityChildrenVector&);
     virtual String stringValue() const;
 
     // ARIA attributes.
     virtual AccessibilityObject* activeDescendant() const;
     virtual void ariaFlowToElements(AccessibilityChildrenVector&) const;
     virtual bool ariaHasPopup() const;
     virtual void ariaOwnsElements(AccessibilityChildrenVector&) const;
     virtual bool ariaRoleHasPresentationalChildren() const;
     virtual void determineARIADropEffects(Vector<String>&);
@@ skipping 10 matching lines @@
     virtual const AtomicString& ariaLiveRegionRelevant() const;
     virtual bool ariaLiveRegionAtomic() const;
     virtual bool ariaLiveRegionBusy() const;
 
     // Accessibility Text.
     virtual String textUnderElement() const;
 
     // Accessibility Text - (To be deprecated).
     virtual String helpText() const;
 
-    // Position and size.
-    virtual LayoutRect boundingBoxRect() const;
+    // Location and click point in frame-relative coordinates.
+    virtual void updateCachedElementRect();
+    virtual void markCachedElementRectDirty();
     virtual IntPoint clickPoint();
 
     // Hit testing.
     virtual AccessibilityObject* accessibilityHitTest(const IntPoint&) const;
-    virtual AccessibilityObject* elementAccessibilityHitTest(const IntPoint&) const;
+    virtual AccessibilityObject* elementAccessibilityHitTest(const IntPoint&);
 
     // High-level accessibility tree access. Other modules should only use these functions.
     virtual AccessibilityObject* parentObject() const;
     virtual AccessibilityObject* parentObjectIfExists() const;
 
     // Low-level accessibility tree exploration, only for use within the accessibility module.
     virtual AccessibilityObject* firstChild() const;
     virtual AccessibilityObject* lastChild() const;
     virtual AccessibilityObject* previousSibling() const;
     virtual AccessibilityObject* nextSibling() const;
@@ skipping 63 matching lines @@
     void addRadioButtonGroupMembers(AccessibilityChildrenVector& linkedUIElements) const;
     AccessibilityObject* internalLinkElement() const;
     AccessibilityObject* accessibilityImageMapHitTest(HTMLAreaElement*, const IntPoint&) const;
     AccessibilityObject* accessibilityParentForImageMap(HTMLMapElement*) const;
     bool renderObjectIsObservable(RenderObject*) const;
     RenderObject* renderParentObject() const;
     bool isDescendantOfElementType(const QualifiedName& tagName) const;
     bool isSVGImage() const;
     void detachRemoteSVGRoot();
     AccessibilitySVGRoot* remoteSVGRootElement() const;
-    AccessibilityObject* remoteSVGElementHitTest(const IntPoint&) const;
+    AccessibilityObject* remoteSVGElementHitTest(const IntPoint&);
     void offsetBoundingBoxForRemoteSVGElement(LayoutRect&) const;
     void addHiddenChildren();
     void addTextFieldChildren();
     void addImageMapChildren();
     void addCanvasChildren();
     void addAttachmentChildren();
     void addRemoteSVGChildren();
     void ariaSelectedRows(AccessibilityChildrenVector&);
     bool elementAttributeValue(const QualifiedName&) const;
     bool inheritsPresentationalRole() const;
+    LayoutRect computeElementRect();

[Julien - ping for review, 2013/05/03 20:54:20]

This method should really be const as you wouldn't expect it to actually modify
the object. It's unfortunate some of the called APIs are not const for no good
reason I could think about.

[dmazzoni, 2013/05/06 04:58:01]

Done.

 };
 
 inline AccessibilityRenderObject* toAccessibilityRenderObject(AccessibilityObject* object)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isAccessibilityRenderObject());
     return static_cast<AccessibilityRenderObject*>(object);
 }
 
 inline const AccessibilityRenderObject* toAccessibilityRenderObject(const AccessibilityObject* object)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isAccessibilityRenderObject());
     return static_cast<const AccessibilityRenderObject*>(object);
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toAccessibilityRenderObject(const AccessibilityRenderObject*);
 
 } // namespace WebCore
 
 #endif // AccessibilityRenderObject_h