include/wx/dfb/ifacehelpers.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/dfb/ifacehelpers.h
   3 // Purpose:     helpers for dealing with DFB interfaces
   4 // Author:      Vaclav Slavik
   5 // Created:     2006-08-09
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 2006 REA Elektronik GmbH
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_DFB_IFACEHELPERS_H_
  12 #define _WX_DFB_IFACEHELPERS_H_
  13
  14 //-----------------------------------------------------------------------------
  15 // wxDFB_DECLARE_INTERFACE
  16 //-----------------------------------------------------------------------------
  17
  18 /**
  19     Forward declares DirectFB interface @a name.
  20
  21     Also declares name##Ptr typedef for wxDfbPtr<name> pointer.
  22
  23     @param name  name of the DirectFB interface
  24  */
  25 #define wxDFB_DECLARE_INTERFACE(name)            \
  26     struct _##name;                              \
  27     typedef _##name name;                        \
  28     typedef wxDfbPtr<name> name##Ptr;
  29
  30
  31 //-----------------------------------------------------------------------------
  32 // wxDfbPtr
  33 //-----------------------------------------------------------------------------
  34
  35 // base class for wxDfbPtr
  36 class wxDfbPtrBase
  37 {
  38 protected:
  39     // increment/decrement refcount; see ifacehelpers.cpp for why using
  40     // void* is safe
  41     static void DoAddRef(void *ptr);
  42     static void DoRelease(void *ptr);
  43 };
  44
  45 /**
  46     This template implements smart pointer for keeping pointers to DirectFB
  47     interfaces. Interface's reference count is increased on copying and the
  48     interface is released when the pointer is deleted.
  49  */
  50 template<typename T>
  51 class wxDfbPtr : private wxDfbPtrBase
  52 {
  53 public:
  54     /**
  55         Creates the pointer from raw interface pointer.
  56
  57         Takes ownership of @a ptr, i.e. AddRef() is @em not called on it.
  58      */
  59     wxDfbPtr(T *ptr = NULL) : m_ptr(ptr) {}
  60
  61     /// Copy ctor
  62     wxDfbPtr(const wxDfbPtr& ptr) { InitFrom(ptr); }
  63
  64     /// Dtor. Releases the interface
  65     ~wxDfbPtr() { Reset(); }
  66
  67     /// Resets the pointer to NULL, decreasing reference count of the interface.
  68     void Reset()
  69     {
  70         if ( m_ptr )
  71         {
  72             DoRelease(m_ptr);
  73             m_ptr = NULL;
  74         }
  75     }
  76
  77     /// Cast to raw pointer
  78     operator T*() const { return m_ptr; }
  79
  80     /**
  81         Cast to @em writeable raw pointer so that code like
  82         "dfb->CreateFont(dfb, NULL, &desc, &fontPtr)" works.
  83
  84         Note that this operator calls Reset(), so using it looses the value.
  85      */
  86     T** operator&()
  87     {
  88         Reset();
  89         return &m_ptr;
  90     }
  91
  92     // standard operators:
  93
  94     wxDfbPtr& operator=(const wxDfbPtr& ptr)
  95     {
  96         Reset();
  97         InitFrom(ptr);
  98         return *this;
  99     }
 100
 101     T& operator*() const { return *m_ptr; }
 102     T* operator->() const { return m_ptr; }
 103
 104 private:
 105     void InitFrom(const wxDfbPtr& ptr)
 106     {
 107         m_ptr = ptr.m_ptr;
 108         if ( m_ptr )
 109             DoAddRef(m_ptr);
 110     }
 111
 112 private:
 113     T *m_ptr;
 114 };
 115
 116 #endif // _WX_DFB_IFACEHELPERS_H_