include/vcl/scopedbitmapaccess.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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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( nullptr ),
  54         mpBitmap( &rBitmap )
  55     {
  56         mpAccess = (mpBitmap->*Acquire)();
  57     }
  58
  59     ScopedBitmapAccess( Access* pAccess, Bitmap& rBitmap ) :
  60         mpAccess( pAccess ),
  61         mpBitmap( &rBitmap )
  62     {
  63     }
  64
  65     ScopedBitmapAccess( ) :
  66         mpAccess( nullptr ),
  67         mpBitmap( nullptr )
  68     {
  69     }
  70
  71     // Move semantics
  72     ScopedBitmapAccess &operator=(ScopedBitmapAccess&&other)
  73     {
  74         mpAccess=other.mpAccess;
  75         mpBitmap=other.mpBitmap;
  76         other.mpAccess = nullptr;
  77         other.mpBitmap = nullptr;
  78         return *this;
  79      }
  80
  81     // Disable copy from lvalue.
  82     ScopedBitmapAccess(const ScopedBitmapAccess&) = delete;
  83     ScopedBitmapAccess &operator=(const ScopedBitmapAccess&) = delete;
  84
  85     ~ScopedBitmapAccess()
  86     {
  87         if (mpAccess)
  88            mpBitmap->ReleaseAccess( mpAccess );
  89     }
  90
  91     void reset()
  92     {
  93         if (mpAccess)
  94         {
  95            mpBitmap->ReleaseAccess( mpAccess );
  96            mpAccess = nullptr;
  97         }
  98     }
  99
 100     bool operator!() const { return !mpAccess; }
 101     operator unspecified_bool_type() const
 102     {
 103         return mpAccess ? &self_type::operator! : 0;
 104     }
 105
 106     Access*         get() { return mpAccess; }
 107     const Access*   get() const { return mpAccess; }
 108
 109     Access*         operator->() { return mpAccess; }
 110     const Access*   operator->() const { return mpAccess; }
 111
 112     Access&         operator*() { return *mpAccess; }
 113     const Access&   operator*() const { return *mpAccess; }
 114
 115 private:
 116     Access*     mpAccess;
 117     Bitmap*     mpBitmap;
 118 };
 119
 120 }
 121
 122 #endif // INCLUDED_VCL_SCOPEDBITMAPACCESS_HXX
 123
 124 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */