include/vcl/scopedbitmapaccess.hxx

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  19
  20 #ifndef INCLUDED_VCL_SCOPEDBITMAPACCESS_HXX
  21 #define INCLUDED_VCL_SCOPEDBITMAPACCESS_HXX
  22
  23 namespace vcl
  24 {
  25
  26 /** This template handles BitmapAccess the RAII way.
  27
  28     Please don't use directly, but through the ready-made typedefs
  29     ScopedReadAccess and ScopedWriteAccess in classes Bitmap and
  30     AlphaMask.
  31
  32     Use as follows:
  33     Bitmap aBitmap;
  34     Bitmap::ScopedReadAccess pReadAccess( aBitmap );
  35     pReadAccess->SetPixel()...
  36
  37     Bitmap aBitmap2;
  38     Bitmap::ScopedWriteAccess pWriteAccess( bCond ? aBitmap2.AcquireWriteAccess() : 0, aBitmap2 );
  39     if ( pWriteAccess )...
  40
  41     @attention for practical reasons, ScopedBitmapAccess stores a
  42     reference to the provided bitmap, thus, make sure that the bitmap
  43     specified at construction time lives at least as long as the
  44     ScopedBitmapAccess.
  45  */
  46 template < class Access, class Bitmap, Access* (Bitmap::* Acquire)() > class ScopedBitmapAccess
  47 {
  48     typedef ScopedBitmapAccess< Access, Bitmap, Acquire > self_type;
  49     typedef bool (self_type::* unspecified_bool_type)() const;
  50
  51 public:
  52     explicit ScopedBitmapAccess( Bitmap& rBitmap ) :
  53         mpAccess( 0 ),
  54         mrBitmap( rBitmap )
  55     {
  56         mpAccess = (mrBitmap.*Acquire)();
  57     }
  58
  59     ScopedBitmapAccess( Access* pAccess, Bitmap& rBitmap ) :
  60         mpAccess( pAccess ),
  61         mrBitmap( rBitmap )
  62     {
  63     }
  64
  65     ~ScopedBitmapAccess()
  66     {
  67         mrBitmap.ReleaseAccess( mpAccess );
  68     }
  69
  70     bool operator!() const { return !mpAccess; }
  71     operator unspecified_bool_type() const
  72     {
  73         return mpAccess ? &self_type::operator! : 0;
  74     }
  75
  76     Access*         get() { return mpAccess; }
  77     const Access*   get() const { return mpAccess; }
  78
  79     Access*         operator->() { return mpAccess; }
  80     const Access*   operator->() const { return mpAccess; }
  81
  82     Access&         operator*() { return *mpAccess; }
  83     const Access&   operator*() const { return *mpAccess; }
  84
  85 private:
  86     Access*     mpAccess;
  87     Bitmap&     mrBitmap;
  88 };
  89
  90 }
  91
  92 #endif // INCLUDED_VCL_SCOPEDBITMAPACCESS_HXX
  93
  94 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */