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.  The {\bf
  15 wxToolBarSimple} class is implemented using bitmaps, and the toolbar demo
  16 shows one of the toolbar bitmaps being used for drawing a miniature
  17 version of the graphic which appears on the main window.
  18
  19 See \helpref{wxMemoryDC}{wxmemorydc} for an example of drawing onto a bitmap.
  20
  21 All wxWidgets platforms support XPMs for small bitmaps and icons.
  22 You may include the XPM inline as below, since it's C code, or you
  23 can load it at run-time.
  24
  25 \begin{verbatim}
  26 #include "mondrian.xpm"
  27 \end{verbatim}
  28
  29 Sometimes you wish to use a .ico resource on Windows, and XPMs on
  30 other platforms (for example to take advantage of Windows' support for multiple icon resolutions).
  31 A macro, \helpref{wxICON}{wxiconmacro}, is available which creates an icon using an XPM
  32 on the appropriate platform, or an icon resource on Windows.
  33
  34 \begin{verbatim}
  35 wxIcon icon(wxICON(mondrian));
  36
  37 // Equivalent to:
  38
  39 #if defined(__WXGTK__) || defined(__WXMOTIF__)
  40 wxIcon icon(mondrian_xpm);
  41 #endif
  42
  43 #if defined(__WXMSW__)
  44 wxIcon icon("mondrian");
  45 #endif
  46 \end{verbatim}
  47
  48 There is also a corresponding \helpref{wxBITMAP}{wxbitmapmacro} macro which allows
  49 to create the bitmaps in much the same way as \helpref{wxICON}{wxiconmacro} creates
  50 icons. It assumes that bitmaps live in resources under Windows or OS2 and XPM
  51 files under all other platforms (for XPMs, the corresponding file must be
  52 included before this macro is used, of course, and the name of the bitmap
  53 should be the same as the resource name under Windows with {\tt \_xpm}
  54 suffix). For example:
  55
  56 \begin{verbatim}
  57 // an easy and portable way to create a bitmap
  58 wxBitmap bmp(wxBITMAP(bmpname));
  59
  60 // which is roughly equivalent to the following
  61 #if defined(__WXMSW__) || defined(__WXPM__)
  62     wxBitmap bmp("bmpname", wxBITMAP_TYPE_RESOURCE);
  63 #else // Unix
  64     wxBitmap bmp(bmpname_xpm, wxBITMAP_TYPE_XPM);
  65 #endif
  66 \end{verbatim}
  67
  68 You should always use wxICON and wxBITMAP macros because they work for any
  69 platform (unlike the code above which doesn't deal with wxMac, wxX11, ...) and
  70 are more short and clear than versions with {\tt \#ifdef}s. Even better,
  71 use the same XPMs on all platforms.
  72
  73 \subsection{Supported bitmap file formats}\label{supportedbitmapformats}
  74
  75 The following lists the formats handled on different platforms. Note
  76 that missing or partially-implemented formats are automatically supplemented
  77 by the \helpref{wxImage}{wximage} to load the data, and then converting
  78 it to wxBitmap form. Note that using wxImage is the preferred way to
  79 load images in wxWidgets, with the exception of resources (XPM-files or
  80 native Windows resources). Writing an image format handler for wxImage
  81 is also far easier than writing one for wxBitmap, because wxImage has
  82 exactly one format on all platforms whereas wxBitmap can store pixel data
  83 very differently, depending on colour depths and platform.
  84
  85 \wxheading{wxBitmap}
  86
  87 Under Windows, wxBitmap may load the following formats:
  88
  89 \begin{itemize}\itemsep=0pt
  90 \item Windows bitmap resource (wxBITMAP\_TYPE\_BMP\_RESOURCE)
  91 \item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
  92 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
  93 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
  94 \end{itemize}
  95
  96 Under wxGTK, wxBitmap may load the following formats:
  97
  98 \begin{itemize}\itemsep=0pt
  99 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 100 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
 101 \end{itemize}
 102
 103 Under wxMotif and wxX11, wxBitmap may load the following formats:
 104
 105 \begin{itemize}\itemsep=0pt
 106 \item XBM data and file (wxBITMAP\_TYPE\_XBM)
 107 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 108 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
 109 \end{itemize}
 110
 111 \wxheading{wxIcon}
 112
 113 Under Windows, wxIcon may load the following formats:
 114
 115 \begin{itemize}\itemsep=0pt
 116 \item Windows icon resource (wxBITMAP\_TYPE\_ICO\_RESOURCE)
 117 \item Windows icon file (wxBITMAP\_TYPE\_ICO)
 118 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 119 \end{itemize}
 120
 121 Under wxGTK, wxIcon may load the following formats:
 122
 123 \begin{itemize}\itemsep=0pt
 124 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 125 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
 126 \end{itemize}
 127
 128 Under wxMotif and wxX11, wxIcon may load the following formats:
 129
 130 \begin{itemize}\itemsep=0pt
 131 \item XBM data and file (wxBITMAP\_TYPE\_XBM)
 132 \item XPM data and file (wxBITMAP\_TYPE\_XPM)
 133 \item All formats that are supported by the \helpref{wxImage}{wximage} class.
 134 \end{itemize}
 135
 136 \wxheading{wxCursor}
 137
 138 Under Windows, wxCursor may load the following formats:
 139
 140 \begin{itemize}\itemsep=0pt
 141 \item Windows cursor resource (wxBITMAP\_TYPE\_CUR\_RESOURCE)
 142 \item Windows cursor file (wxBITMAP\_TYPE\_CUR)
 143 \item Windows icon file (wxBITMAP\_TYPE\_ICO)
 144 \item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
 145 \end{itemize}
 146
 147 Under wxGTK, wxCursor may load the following formats (in additional
 148 to stock cursors):
 149
 150 \begin{itemize}\itemsep=0pt
 151 \item None (stock cursors only).
 152 \end{itemize}
 153
 154 Under wxMotif and wxX11, wxCursor may load the following formats:
 155
 156 \begin{itemize}\itemsep=0pt
 157 \item XBM data and file (wxBITMAP\_TYPE\_XBM)
 158 \end{itemize}
 159
 160 \subsection{Bitmap format handlers}\label{bitmaphandlers}
 161
 162 To provide extensibility, the functionality for loading and saving bitmap formats
 163 is not implemented in the wxBitmap class, but in a number of handler classes,
 164 derived from wxBitmapHandler. There is a static list of handlers which wxBitmap
 165 examines when a file load/save operation is requested. Some handlers are provided as standard, but if you
 166 have special requirements, you may wish to initialise the wxBitmap class with
 167 some extra handlers which you write yourself or receive from a third party.
 168
 169 To add a handler object to wxBitmap, your application needs to include the header which implements it, and
 170 then call the static function \helpref{wxBitmap::AddHandler}{wxbitmapaddhandler}.
 171
 172 {\bf Note:} bitmap handlers are not implemented on all platforms, and new ones rarely need
 173 to be implemented since wxImage can be used for loading most formats, as noted earlier.
 174