docs/latex/wx/bmpdatob.tex

   1 \section{\class{wxBitmapDataObject}}\label{wxbitmapdataobject}
   2
   3 wxBitmapDataObject is a specialization of wxDataObject for bitmap data. It can be
   4 used without change to paste data into the \helpref{wxClipboard}{wxclipboard}
   5 or a \helpref{wxDropSource}{wxdropsource}. A user may wish to derive a new class
   6 from this class for providing a bitmap on-demand in order to minimize memory consumption
   7 when offering data in several formats, such as a bitmap and GIF.
   8
   9 In order to offer bitmap data on-demand \helpref{GetSize}{wxbitmapdataobjectgetsize}
  10 and \helpref{WriteData}{wxbitmapdataobjectwritedata} will have to be overridden.
  11
  12 \wxheading{Derived from}
  13
  14 \helpref{wxDataObject}{wxdataobject}
  15
  16 \wxheading{See also}
  17
  18 \helpref{wxDataObject}{wxdataobject}
  19
  20 \latexignore{\rtfignore{\wxheading{Members}}}
  21
  22 \membersection{wxBitmapDataObject::wxBitmapDataObject}\label{wxbitmapdataobjectwxbitmapdataobject}
  23
  24 \func{}{wxBitmapDataObject}{\void}
  25
  26 Default constructor. Call \helpref{SetBitmap}{wxbitmapdataobjectsetbitmap} later
  27 or override \helpref{WriteData}{wxbitmapdataobjectwritedata} and
  28 \helpref{GetSize}{wxbitmapdataobjectgetsize} for providing data on-demand.
  29
  30 \func{}{wxBitmapDataObject}{\param{const wxBitmap\& }{bitmap}}
  31
  32 Constructor, passing a bitmap.
  33
  34 \membersection{wxBitmapDataObject::GetSize}\label{wxbitmapdataobjectgetsize}
  35
  36 \constfunc{virtual size\_t}{GetSize}{\void}
  37
  38 Returns the data size. By default, returns the size of the bitmap data
  39 set in the constructor or using \helpref{SetBitmap}{wxbitmapdataobjectsetbitmap}.
  40 This can be overridden to provide size data on-demand. Note that you'd
  41 have to call the inherited GetSize method as this is the only way
  42 to get to know the transfer size of the bitmap in a platform dependent
  43 way - a bitmap has different size under GTK and Windows. In practice,
  44 this would look like this:
  45
  46 \begin{verbatim}
  47 size_t MyBitmapDataObject::GetSize()
  48 {
  49   // Get bitmap from global container. This container
  50   // should be able to "produce" data in all formats
  51   // offered by the application but store it only in
  52   // one format to reduce memory consumption.
  53
  54   wxBitmap my_bitmap = my_global_container->GetBitmap();
  55
  56   // temporarily set bitmap
  57
  58   SetBitmap( my_bitmap );
  59
  60   size_t ret = wxBitmapDataObject::GetSize();
  61
  62   // unset bitmap again
  63
  64   SetBitmap( wxNullBitmap );
  65
  66   retrun ret;
  67 }
  68 \end{verbatim}
  69
  70 TODO: Offer a nicer way to do this. Maybe by providing a platform
  71 dependent function in this class like
  72 \begin{verbatim}
  73 size_t GetBitmapSize( const wxBitmap &bitmap )
  74 \end{verbatim}
  75
  76 \membersection{wxBitmapDataObject::GetBitmap}\label{wxbitmapdataobjectgettext}
  77
  78 \constfunc{virtual wxBitmap}{GetBitmap}{\void}
  79
  80 Returns the bitmap associated with the data object. You may wish to override
  81 this method when offering data on-demand, but this is not required by
  82 wxWindows' internals. Use this method to get data in bitmap form from
  83 the \helpref{wxClipboard}{wxclipboard}.
  84
  85 \membersection{wxBitmapDataObject::SetBitmap}\label{wxbitmapdataobjectsetbitmap}
  86
  87 \func{virtual void}{SetBitmap}{\param{const wxBitmap\& }{bitmap}}
  88
  89 Sets the bitmap associated with the data object. This method is called
  90 internally when retrieving data from the \helpref{wxClipboard}{wxclipboard}
  91 and may be used to paste data to the clipboard directly (instead of
  92 on-demand).
  93
  94 \membersection{wxBitmapDataObject::WriteData}\label{wxbitmapdataobjectwritedata}
  95
  96 \constfunc{virtual void}{WriteData}{\param{void}{*dest} }
  97
  98 Write the data owned by this class to {\it dest}. By default, this
  99 calls \helpref{WriteBitmap}{wxbitmapdataobjectwritebitmap} with the bitmap
 100 set in the constructor or using \helpref{SetBitmap}{wxbitmapdataobjectsetbitmap}.
 101 This can be overridden to provide bitmap data on-demand; in this case
 102 \helpref{WriteBitmap}{wxbitmapdataobjectwritebitmap} must be called from
 103 within th overriding WriteData() method.
 104
 105 \membersection{wxBitmapDataObject::WriteBitmap}\label{wxbitmapdataobjectwritebitmap}
 106
 107 \constfunc{void}{WriteBitmap}{\param{const wxBitmap\& }{bitmap}\param{void}{*dest} }
 108
 109 Writes the the bitmap {\it bitmap} to {\it dest}. This method must be called
 110 from \helpref{WriteData}{wxbitmapdataobjectwritedata}.
 111