ref-counting vcl::Window subclasses

Points of discussion
--------------------

(*) where in the Window destructor should dispose() be called?
It's a seriously large method.

(*) we're going to need similar typedefs and declarations for every
single sub-class of vcl::Window, I assume that I will need to create a
macro to make it less verbose.

TODO
----

Update clang plugin to verify that:
(a) dispose() methods always call their superclass dispose()
(b) dispose() methods don't forget to clear any references owned
by that class.

Change-Id: I873d5d5166f811e2f65e49327cc98862559fcf30

5 files changed, 39 insertions, 14 deletions

diff --git a/include/svtools/valueset.hxx b/include/svtools/valueset.hxx
index e82a4b4ce353..4ddc64db36e4 100644
--- a/include/svtools/valueset.hxx
+++ b/include/svtools/valueset.hxx
@@ -177,7 +177,6 @@ to be set (before Show) with SetStyle().
 *************************************************************************/
 
 typedef std::vector<ValueSetItem*> ValueItemList;
-typedef boost::scoped_ptr<ScrollBar> ScrollBarPtr;
 typedef boost::scoped_ptr<ValueSetItem> ValueSetItemPtr;
 
 // - ValueSet types -
@@ -202,7 +201,7 @@ private:
     Timer           maTimer;
     ValueItemList   mItemList;
     ValueSetItemPtr mpNoneItem;
-    ScrollBarPtr    mpScrollBar;
+    boost::scoped_ptr<ScrollBar> mpScrollBar;
     Rectangle       maNoneItemRect;
     Rectangle       maItemListRect;
     long            mnItemWidth;
diff --git a/include/vcl/button.hxx b/include/vcl/button.hxx
index 6c9384cdd5c5..9f5142aebf3a 100644
--- a/include/vcl/button.hxx
+++ b/include/vcl/button.hxx
@@ -566,6 +566,8 @@ public:
     virtual void    KeyInput( const KeyEvent& rKEvt ) SAL_OVERRIDE;
 };
 
+typedef rtl::Reference<DisclosureButton> DisclosureButtonPtr;
+
 #endif // INCLUDED_VCL_BUTTON_HXX
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/include/vcl/layout.hxx b/include/vcl/layout.hxx
index 0eed7cb6f723..88f1887750a8 100644
--- a/include/vcl/layout.hxx
+++ b/include/vcl/layout.hxx
@@ -513,29 +513,29 @@ public:
     VclExpander(vcl::Window *pParent)
         : VclBin(pParent)
         , m_bResizeTopLevel(true)
-        , m_aDisclosureButton(this)
+        , m_pDisclosureButton(new DisclosureButton(this))
     {
-        m_aDisclosureButton.SetToggleHdl(LINK(this, VclExpander, ClickHdl));
-        m_aDisclosureButton.Show();
+        m_pDisclosureButton->SetToggleHdl(LINK(this, VclExpander, ClickHdl));
+        m_pDisclosureButton->Show();
     }
     virtual vcl::Window *get_child() SAL_OVERRIDE;
     virtual const vcl::Window *get_child() const SAL_OVERRIDE;
     virtual bool set_property(const OString &rKey, const OString &rValue) SAL_OVERRIDE;
     bool get_expanded() const
     {
-        return m_aDisclosureButton.IsChecked();
+        return m_pDisclosureButton->IsChecked();
     }
     void set_expanded(bool bExpanded)
     {
-        m_aDisclosureButton.Check(bExpanded);
+        m_pDisclosureButton->Check(bExpanded);
     }
     void set_label(const OUString& rLabel)
     {
-        m_aDisclosureButton.SetText(rLabel);
+        m_pDisclosureButton->SetText(rLabel);
     }
     OUString get_label() const
     {
-        return m_aDisclosureButton.GetText();
+        return m_pDisclosureButton->GetText();
     }
     virtual void StateChanged(StateChangedType nType) SAL_OVERRIDE;
     void  SetExpandedHdl( const Link& rLink ) { maExpandedHdl = rLink; }
@@ -543,9 +543,10 @@ public:
 protected:
     virtual Size calculateRequisition() const SAL_OVERRIDE;
     virtual void setAllocation(const Size &rAllocation) SAL_OVERRIDE;
+    void dispose() SAL_OVERRIDE { m_pDisclosureButton.clear(); VclBin::dispose(); }
 private:
     bool m_bResizeTopLevel;
-    DisclosureButton m_aDisclosureButton;
+    DisclosureButtonPtr m_pDisclosureButton;
     Link maExpandedHdl;
     DECL_DLLPRIVATE_LINK(ClickHdl, DisclosureButton* pBtn);
 };
@@ -557,8 +558,8 @@ public:
     virtual vcl::Window *get_child() SAL_OVERRIDE;
     virtual const vcl::Window *get_child() const SAL_OVERRIDE;
     virtual bool set_property(const OString &rKey, const OString &rValue) SAL_OVERRIDE;
-    ScrollBar& getVertScrollBar() { return m_aVScroll; }
-    ScrollBar& getHorzScrollBar() { return m_aHScroll; }
+    ScrollBar& getVertScrollBar() { return *m_pVScroll.get(); }
+    ScrollBar& getHorzScrollBar() { return *m_pHScroll.get(); }
     Size getVisibleChildSize() const;
     //set to true to disable the built-in scrolling callbacks to allow the user
     //to override it
@@ -569,10 +570,11 @@ protected:
     DECL_LINK(ScrollBarHdl, void *);
     void InitScrollBars(const Size &rRequest);
     virtual bool Notify(NotifyEvent& rNEvt) SAL_OVERRIDE;
+    void dispose() SAL_OVERRIDE { m_pVScroll.clear(); m_pHScroll.clear(); VclBin::dispose(); }
 private:
     bool m_bUserManagedScrolling;
-    ScrollBar m_aVScroll;
-    ScrollBar m_aHScroll;
+    ScrollBarPtr m_pVScroll;
+    ScrollBarPtr m_pHScroll;
     ScrollBarBox m_aScrollBarBox;
 };
 
diff --git a/include/vcl/scrbar.hxx b/include/vcl/scrbar.hxx
index 65bbca0dc2fe..db0a673842d7 100644
--- a/include/vcl/scrbar.hxx
+++ b/include/vcl/scrbar.hxx
@@ -141,6 +141,8 @@ public:
     virtual Size    GetOptimalSize() const SAL_OVERRIDE;
 };
 
+typedef rtl::Reference<ScrollBar> ScrollBarPtr;
+
 
 // - ScrollBarBox -
 
diff --git a/include/vcl/window.hxx b/include/vcl/window.hxx
index 44ab2c0b5ae9..ec51588f16d1 100644
--- a/include/vcl/window.hxx
+++ b/include/vcl/window.hxx
@@ -36,6 +36,7 @@
 #include <vcl/region.hxx>
 #include <vcl/salnativewidgets.hxx>
 #include <rtl/ustring.hxx>
+#include <rtl/ref.hxx>
 #include <cppuhelper/weakref.hxx>
 #include <com/sun/star/uno/Reference.hxx>
 #include <boost/shared_ptr.hpp>
@@ -399,6 +400,8 @@ private:
     // OutputDevice
     ::OutputDevice* mpOutputDevice;
 
+    mutable int mnRefCnt;        // reference count
+
 #ifdef DBG_UTIL
     friend const char* ::ImplDbgCheckWindow( const void* pObj );
 #endif
@@ -478,8 +481,25 @@ public:
 
     SAL_DLLPRIVATE static void          ImplCalcSymbolRect( Rectangle& rRect );
 
+private:
+    template<typename T> friend class ::rtl::Reference;
+
+    inline void acquire() const
+    {
+        mnRefCnt++;
+    }
+
+    inline void release() const
+    {
+        if (!--mnRefCnt)
+            delete const_cast<Window*>(this);
+    }
+
 protected:
 
+    /** This is intended to be used to clear any locally held references to other Window-subclass objects */
+    virtual void dispose() {}
+
     SAL_DLLPRIVATE void                 ImplInit( vcl::Window* pParent, WinBits nStyle, SystemParentData* pSystemParentData );
 
     SAL_DLLPRIVATE Point                ImplOutputToFrame( const Point& rPos );