A bitmap created dynamically or loaded from a file can be selected
into a memory device context (instance of \helpref{wxMemoryDC}{wxmemorydc}). This
enables the bitmap to be copied to a window or memory device context
-using \helpref{wxDC::Blit}{wxdcblit}, or to be used as a drawing surface. The {\bf
-wxToolBarSimple} class is implemented using bitmaps, and the toolbar demo
-shows one of the toolbar bitmaps being used for drawing a miniature
-version of the graphic which appears on the main window.
+using \helpref{wxDC::Blit}{wxdcblit}, or to be used as a drawing surface.
See \helpref{wxMemoryDC}{wxmemorydc} for an example of drawing onto a bitmap.
-The following shows the conditional compilation required to load a
-bitmap under Unix and in Windows. The alternative is to use the string
-version of the bitmap constructor, which loads a file under Unix and a
-resource or file under Windows, but has the disadvantage of requiring the
-XPM icon file to be available at run-time.
+All wxWidgets platforms support XPMs for small bitmaps and icons.
+You may include the XPM inline as below, since it's C code, or you
+can load it at run-time.
\begin{verbatim}
-#if defined(__WXGTK__) || defined(__WXMOTIF__)
#include "mondrian.xpm"
-#endif
\end{verbatim}
-A macro, wxICON, is available which creates an icon using an XPM
+Sometimes you wish to use a .ico resource on Windows, and XPMs on
+other platforms (for example to take advantage of Windows' support for multiple icon resolutions).
+A macro, \helpref{wxICON}{wxiconmacro}, is available which creates an icon using an XPM
on the appropriate platform, or an icon resource on Windows.
\begin{verbatim}
#endif
\end{verbatim}
+There is also a corresponding \helpref{wxBITMAP}{wxbitmapmacro} macro which allows
+to create the bitmaps in much the same way as \helpref{wxICON}{wxiconmacro} creates
+icons. It assumes that bitmaps live in resources under Windows or OS2 and XPM
+files under all other platforms (for XPMs, the corresponding file must be
+included before this macro is used, of course, and the name of the bitmap
+should be the same as the resource name under Windows with {\tt \_xpm}
+suffix). For example:
+
+\begin{verbatim}
+// an easy and portable way to create a bitmap
+wxBitmap bmp(wxBITMAP(bmpname));
+
+// which is roughly equivalent to the following
+#if defined(__WXMSW__) || defined(__WXPM__)
+ wxBitmap bmp("bmpname", wxBITMAP_TYPE_RESOURCE);
+#else // Unix
+ wxBitmap bmp(bmpname_xpm, wxBITMAP_TYPE_XPM);
+#endif
+\end{verbatim}
+
+You should always use wxICON and wxBITMAP macros because they work for any
+platform (unlike the code above which doesn't deal with wxMac, wxX11, ...) and
+are more short and clear than versions with {\tt \#ifdef}s. Even better,
+use the same XPMs on all platforms.
+
\subsection{Supported bitmap file formats}\label{supportedbitmapformats}
The following lists the formats handled on different platforms. Note
-that missing or partially-implemented formats can be supplemented
-by using \helpref{wxImage}{wximage} to load the data, and then converting
-it to wxBitmap form.
+that missing or partially-implemented formats are automatically supplemented
+by the \helpref{wxImage}{wximage} to load the data, and then converting
+it to wxBitmap form. Note that using wxImage is the preferred way to
+load images in wxWidgets, with the exception of resources (XPM-files or
+native Windows resources). Writing an image format handler for wxImage
+is also far easier than writing one for wxBitmap, because wxImage has
+exactly one format on all platforms whereas wxBitmap can store pixel data
+very differently, depending on colour depths and platform.
\wxheading{wxBitmap}
\begin{itemize}\itemsep=0pt
\item Windows bitmap resource (wxBITMAP\_TYPE\_BMP\_RESOURCE)
\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
-\item PNG file (wxBITMAP\_TYPE\_PNG). Currently 4-bit (16-colour) PNG files do not load properly.
\item XPM data and file (wxBITMAP\_TYPE\_XPM)
+\item All formats that are supported by the \helpref{wxImage}{wximage} class.
\end{itemize}
Under wxGTK, wxBitmap may load the following formats:
\begin{itemize}\itemsep=0pt
-\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
-\item PNG (wxBITMAP\_TYPE\_PNG).
\item XPM data and file (wxBITMAP\_TYPE\_XPM)
+\item All formats that are supported by the \helpref{wxImage}{wximage} class.
\end{itemize}
-Under wxMotif, wxBitmap may load the following formats:
+Under wxMotif and wxX11, wxBitmap may load the following formats:
\begin{itemize}\itemsep=0pt
-%\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
-%\item PNG (wxBITMAP\_TYPE\_PNG).
\item XBM data and file (wxBITMAP\_TYPE\_XBM)
\item XPM data and file (wxBITMAP\_TYPE\_XPM)
+\item All formats that are supported by the \helpref{wxImage}{wximage} class.
\end{itemize}
\wxheading{wxIcon}
Under wxGTK, wxIcon may load the following formats:
\begin{itemize}\itemsep=0pt
-\item PNG (wxBITMAP\_TYPE\_PNG).
\item XPM data and file (wxBITMAP\_TYPE\_XPM)
+\item All formats that are supported by the \helpref{wxImage}{wximage} class.
\end{itemize}
-Under wxMotif, wxIcon may load the following formats:
+Under wxMotif and wxX11, wxIcon may load the following formats:
\begin{itemize}\itemsep=0pt
-%\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
-%\item PNG (wxBITMAP\_TYPE\_PNG).
\item XBM data and file (wxBITMAP\_TYPE\_XBM)
\item XPM data and file (wxBITMAP\_TYPE\_XPM)
+\item All formats that are supported by the \helpref{wxImage}{wximage} class.
\end{itemize}
\wxheading{wxCursor}
\item None (stock cursors only).
\end{itemize}
-Under wxMotif, wxCursor may load the following formats:
+Under wxMotif and wxX11, wxCursor may load the following formats:
\begin{itemize}\itemsep=0pt
\item XBM data and file (wxBITMAP\_TYPE\_XBM)
some extra handlers which you write yourself or receive from a third party.
To add a handler object to wxBitmap, your application needs to include the header which implements it, and
-then call the static function \helpref{wxBitmap::AddHandler}{wxbitmapaddhandler}. For example:
-
-{\small
-\begin{verbatim}
- #include <wx/pnghand.h>
- #include <wx/xpmhand.h>
- ...
- // Initialisation
- wxBitmap::AddHandler(new wxPNGFileHandler);
- wxBitmap::AddHandler(new wxXPMFileHandler);
- wxBitmap::AddHandler(new wxXPMDataHandler);
- ...
-\end{verbatim}
-}
-
-Assuming the handlers have been written correctly, you should now be able to load and save PNG files
-and XPM files using the usual wxBitmap API.
+then call the static function \helpref{wxBitmap::AddHandler}{wxbitmapaddhandler}.
-{\bf Note:} bitmap handlers are not implemented on all platforms. Currently, the above is only necessary on
-Windows, to save the extra overhead of formats that may not be necessary (if you don't use them, they
-are not linked into the executable). Unix platforms have PNG and XPM capability built-in (where supported).
+{\bf Note:} bitmap handlers are not implemented on all platforms, and new ones rarely need
+to be implemented since wxImage can be used for loading most formats, as noted earlier.
projects / wxWidgets.git / blobdiff