docs/latex/wx/tbitmap.tex

   1 \section{Bitmaps and icons overview}\label{wxbitmapoverview}
   2
   3 Classes: \helpref{wxBitmap}{wxbitmap}, \helpref{wxBitmapHandler}{wxbitmaphandler}, \helpref{wxIcon}{wxicon}, \helpref{wxCursor}{wxcursor}.
   4
   5 The wxBitmap class encapsulates the concept of a platform-dependent bitmap,
   6 either monochrome or colour. Platform-specific methods for creating a
   7 wxBitmap object from an existing file are catered for, and
   8 this is an occasion where conditional compilation will sometimes be
   9 required.
  10
  11 A bitmap created dynamically or loaded from a file can be selected
  12 into a memory device context (instance of \helpref{wxMemoryDC}{wxmemorydc}). This
  13 enables the bitmap to be copied to a window or memory device context
  14 using \helpref{wxDC::Blit}{wxdcblit}, or to be used as a drawing surface.
  15
  16 See \helpref{wxMemoryDC}{wxmemorydc} for an example of drawing onto a bitmap.
  17
  18 All wxWidgets platforms support XPMs for small bitmaps and icons.
  19 You may include the XPM inline as below, since it's C code, or you
  20 can load it at run-time.
  21
  22 \begin{verbatim}
  23 #include "mondrian.xpm"
  24 \end{verbatim}
  25
  26 Sometimes you wish to use a .ico resource on Windows, and XPMs on
  27 other platforms (for example to take advantage of Windows' support for multiple icon resolutions).
  28 A macro, \helpref{wxICON}{wxiconmacro}, is available which creates an icon using an XPM
  29 on the appropriate platform, or an icon resource on Windows.
  30
  31 \begin{verbatim}
  32 wxIcon icon(wxICON(mondrian));
  33
  34 // Equivalent to:
  35
  36 #if defined(__WXGTK__) || defined(__WXMOTIF__)
  37 wxIcon icon(mondrian_xpm);
  38 #endif
  39
  40 #if defined(__WXMSW__)
  41 wxIcon icon("mondrian");
  42 #endif
  43 \end{verbatim}
  44
  45 There is also a corresponding \helpref{wxBITMAP}{wxbitmapmacro} macro which allows
  46 to create the bitmaps in much the same way as \helpref{wxICON}{wxiconmacro} creates
  47 icons. It assumes that bitmaps live in resources under Windows or OS2 and XPM
  48 files under all other platforms (for XPMs, the corresponding file must be
  49 included before this macro is used, of course, and the name of the bitmap
  50 should be the same as the resource name under Windows with {\tt \_xpm}
  51 suffix). For example:
  52
  53 \begin{verbatim}
  54 // an easy and portable way to create a bitmap
  55 wxBitmap bmp(wxBITMAP(bmpname));
  56
  57 // which is roughly equivalent to the following
  58 #if defined(__WXMSW__) || defined(__WXPM__)
  59     wxBitmap bmp("bmpname", wxBITMAP_TYPE_RESOURCE);
  60 #else // Unix
  61     wxBitmap bmp(bmpname_xpm, wxBITMAP_TYPE_XPM);
  62 #endif
  63 \end{verbatim}
  64
  65 You should always use wxICON and wxBITMAP macros because they work for any
  66 platform (unlike the code above which doesn't deal with wxMac, wxX11, ...) and
  67 are more short and clear than versions with {\tt \#ifdef}s. Even better,
  68 use the same XPMs on all platforms.
  69
  70 \subsection{Supported bitmap file formats}\label{supportedbitmapformats}
  71
  72 The following lists the formats handled on different platforms. Note
  73 that missing or partially-implemented formats are automatically supplemented
  74 by the \helpref{wxImage}{wximage} to load the data, and then converting
  75 it to wxBitmap form. Note that using wxImage is the preferred way to
  76 load images in wxWidgets, with the exception of resources (XPM-files or
  77 native Windows resources). Writing an image format handler for wxImage
  78 is also far easier than writing one for wxBitmap, because wxImage has
  79 exactly one format on all platforms whereas wxBitmap can store pixel data
  80 very differently, depending on colour depths and platform.
  81
  82 \wxheading{wxBitmap}
  83
  84 Under Windows, wxBitmap may load the following formats:
  85
  86 \begin{itemize}\itemsep=0pt
  87 \item Windows bitmap resource (wxBITMAP\_TYPE\_BMP\_RESOURCE)
  88 \item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
  89 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
  90 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
  91 \end{itemize}
  92
  93 Under wxGTK, wxBitmap may load the following formats:
  94
  95 \begin{itemize}\itemsep=0pt
  96 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
  97 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
  98 \end{itemize}
  99
 100 Under wxMotif and wxX11, wxBitmap may load the following formats:
 101
 102 \begin{itemize}\itemsep=0pt
 103 \item XBM data and file (wxBITMAP\_TYPE\_XBM)
 104 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 105 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
 106 \end{itemize}
 107
 108 \wxheading{wxIcon}
 109
 110 Under Windows, wxIcon may load the following formats:
 111
 112 \begin{itemize}\itemsep=0pt
 113 \item Windows icon resource (wxBITMAP\_TYPE\_ICO\_RESOURCE)
 114 \item Windows icon file (wxBITMAP\_TYPE\_ICO)
 115 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 116 \end{itemize}
 117
 118 Under wxGTK, wxIcon may load the following formats:
 119
 120 \begin{itemize}\itemsep=0pt
 121 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 122 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
 123 \end{itemize}
 124
 125 Under wxMotif and wxX11, wxIcon may load the following formats:
 126
 127 \begin{itemize}\itemsep=0pt
 128 \item XBM data and file (wxBITMAP\_TYPE\_XBM)
 129 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 130 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
 131 \end{itemize}
 132
 133 \wxheading{wxCursor}
 134
 135 Under Windows, wxCursor may load the following formats:
 136
 137 \begin{itemize}\itemsep=0pt
 138 \item Windows cursor resource (wxBITMAP\_TYPE\_CUR\_RESOURCE)
 139 \item Windows cursor file (wxBITMAP\_TYPE\_CUR)
 140 \item Windows icon file (wxBITMAP\_TYPE\_ICO)
 141 \item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
 142 \end{itemize}
 143
 144 Under wxGTK, wxCursor may load the following formats (in additional
 145 to stock cursors):
 146
 147 \begin{itemize}\itemsep=0pt
 148 \item None (stock cursors only).
 149 \end{itemize}
 150
 151 Under wxMotif and wxX11, wxCursor may load the following formats:
 152
 153 \begin{itemize}\itemsep=0pt
 154 \item XBM data and file (wxBITMAP\_TYPE\_XBM)
 155 \end{itemize}
 156
 157 \subsection{Bitmap format handlers}\label{bitmaphandlers}
 158
 159 To provide extensibility, the functionality for loading and saving bitmap formats
 160 is not implemented in the wxBitmap class, but in a number of handler classes,
 161 derived from wxBitmapHandler. There is a static list of handlers which wxBitmap
 162 examines when a file load/save operation is requested. Some handlers are provided as standard, but if you
 163 have special requirements, you may wish to initialise the wxBitmap class with
 164 some extra handlers which you write yourself or receive from a third party.
 165
 166 To add a handler object to wxBitmap, your application needs to include the header which implements it, and
 167 then call the static function \helpref{wxBitmap::AddHandler}{wxbitmapaddhandler}.
 168
 169 {\bf Note:} bitmap handlers are not implemented on all platforms, and new ones rarely need
 170 to be implemented since wxImage can be used for loading most formats, as noted earlier.
 171