include/vcl/scopedbitmapaccess.hxx

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  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
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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     BitmapScopedWriteAccess 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 public:
  49     explicit ScopedBitmapAccess( Bitmap& rBitmap ) :
  50         mpAccess( nullptr ),
  51         mpBitmap( &rBitmap )
  52     {
  53         mpAccess = (mpBitmap->*Acquire)();
  54     }
  55
  56     ScopedBitmapAccess( Access* pAccess, Bitmap& rBitmap ) :
  57         mpAccess( pAccess ),
  58         mpBitmap( &rBitmap )
  59     {
  60     }
  61
  62     ScopedBitmapAccess( ) :
  63         mpAccess( nullptr ),
  64         mpBitmap( nullptr )
  65     {
  66     }
  67
  68     // Move semantics
  69     ScopedBitmapAccess &operator=(ScopedBitmapAccess&&other)
  70     {
  71         mpAccess=other.mpAccess;
  72         mpBitmap=other.mpBitmap;
  73         other.mpAccess = nullptr;
  74         other.mpBitmap = nullptr;
  75         return *this;
  76      }
  77
  78     // Disable copy from lvalue.
  79     ScopedBitmapAccess(const ScopedBitmapAccess&) = delete;
  80     ScopedBitmapAccess &operator=(const ScopedBitmapAccess&) = delete;
  81
  82     ~ScopedBitmapAccess() COVERITY_NOEXCEPT_FALSE
  83     {
  84         if (mpAccess)
  85            mpBitmap->ReleaseAccess( mpAccess );
  86     }
  87
  88     void reset()
  89     {
  90         if (mpAccess)
  91         {
  92            mpBitmap->ReleaseAccess( mpAccess );
  93            mpAccess = nullptr;
  94         }
  95     }
  96
  97     bool operator!() const { return !mpAccess; }
  98     explicit operator bool() const
  99     {
 100         return mpAccess;
 101     }
 102
 103     Access*         get() { return mpAccess; }
 104     const Access*   get() const { return mpAccess; }
 105
 106     Access*         operator->() { return mpAccess; }
 107     const Access*   operator->() const { return mpAccess; }
 108
 109     Access&         operator*() { return *mpAccess; }
 110     const Access&   operator*() const { return *mpAccess; }
 111
 112 private:
 113     Access*     mpAccess;
 114     Bitmap*     mpBitmap;
 115 };
 116
 117 }
 118
 119 #endif // INCLUDED_VCL_SCOPEDBITMAPACCESS_HXX
 120
 121 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */