initial (not yet working) code for DirectFB port

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40865 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/dfb/ifacehelpers.h

@@ -0,0 +1,116 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        wx/dfb/ifacehelpers.h
+// Purpose:     helpers for dealing with DFB interfaces
+// Author:      Vaclav Slavik
+// Created:     2006-08-09
+// RCS-ID:      $Id$
+// Copyright:   (c) 2006 REA Elektronik GmbH
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_DFB_IFACEHELPERS_H_
+#define _WX_DFB_IFACEHELPERS_H_
+
+//-----------------------------------------------------------------------------
+// wxDFB_DECLARE_INTERFACE
+//-----------------------------------------------------------------------------
+
+/**
+    Forward declares DirectFB interface @a name.
+
+    Also declares name##Ptr typedef for wxDfbPtr<name> pointer.
+
+    @param name  name of the DirectFB interface
+ */
+#define wxDFB_DECLARE_INTERFACE(name)            \
+    struct _##name;                              \
+    typedef _##name name;                        \
+    typedef wxDfbPtr<name> name##Ptr;
+
+
+//-----------------------------------------------------------------------------
+// wxDfbPtr
+//-----------------------------------------------------------------------------
+
+// base class for wxDfbPtr
+class wxDfbPtrBase
+{
+protected:
+    // increment/decrement refcount; see ifacehelpers.cpp for why using
+    // void* is safe
+    static void DoAddRef(void *ptr);
+    static void DoRelease(void *ptr);
+};
+
+/**
+    This template implements smart pointer for keeping pointers to DirectFB
+    interfaces. Interface's reference count is increased on copying and the
+    interface is released when the pointer is deleted.
+ */
+template<typename T>
+class wxDfbPtr : private wxDfbPtrBase
+{
+public:
+    /**
+        Creates the pointer from raw interface pointer.
+
+        Takes ownership of @a ptr, i.e. AddRef() is @em not called on it.
+     */
+    wxDfbPtr(T *ptr = NULL) : m_ptr(ptr) {}
+
+    /// Copy ctor
+    wxDfbPtr(const wxDfbPtr& ptr) { InitFrom(ptr); }
+
+    /// Dtor. Releases the interface
+    ~wxDfbPtr() { Reset(); }
+
+    /// Resets the pointer to NULL, decreasing reference count of the interface.
+    void Reset()
+    {
+        if ( m_ptr )
+        {
+            DoRelease(m_ptr);
+            m_ptr = NULL;
+        }
+    }
+
+    /// Cast to raw pointer
+    operator T*() const { return m_ptr; }
+
+    /**
+        Cast to @em writeable raw pointer so that code like
+        "dfb->CreateFont(dfb, NULL, &desc, &fontPtr)" works.
+
+        Note that this operator calls Reset(), so using it looses the value.
+     */
+    T** operator&()
+    {
+        Reset();
+        return &m_ptr;
+    }
+
+    // standard operators:
+
+    wxDfbPtr& operator=(const wxDfbPtr& ptr)
+    {
+        Reset();
+        InitFrom(ptr);
+        return *this;
+    }
+
+    T& operator*() const { return *m_ptr; }
+    T* operator->() const { return m_ptr; }
+
+private:
+    void InitFrom(const wxDfbPtr& ptr)
+    {
+        m_ptr = ptr.m_ptr;
+        if ( m_ptr )
+            DoAddRef(m_ptr);
+    }
+
+private:
+    T *m_ptr;
+};
+
+#endif // _WX_DFB_IFACEHELPERS_H_