0c5d3e1ccd
2. added and documented wxBITMAP() macros (as wxICON) 3. restructured wxFont class, added support of encoding parameter 4. regenerated makefiles to compile the new fontcmn.cpp file 5. corrected bug with non existing files in document-view history git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@3753 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
191 lines
6.8 KiB
TeX
191 lines
6.8 KiB
TeX
\section{Bitmaps and icons overview}\label{wxbitmapoverview}
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Classes: \helpref{wxBitmap}{wxbitmap}, \helpref{wxBitmapHandler}{wxbitmaphandler}, \helpref{wxIcon}{wxicon}, \helpref{wxCursor}{wxcursor}.
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The wxBitmap class encapsulates the concept of a platform-dependent bitmap,
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either monochrome or colour. Platform-specific methods for creating a
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wxBitmap object from an existing file are catered for, and
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this is an occasion where conditional compilation will sometimes be
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required.
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A bitmap created dynamically or loaded from a file can be selected
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into a memory device context (instance of \helpref{wxMemoryDC}{wxmemorydc}). This
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enables the bitmap to be copied to a window or memory device context
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using \helpref{wxDC::Blit}{wxdcblit}, or to be used as a drawing surface. The {\bf
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wxToolBarSimple} class is implemented using bitmaps, and the toolbar demo
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shows one of the toolbar bitmaps being used for drawing a miniature
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version of the graphic which appears on the main window.
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See \helpref{wxMemoryDC}{wxmemorydc} for an example of drawing onto a bitmap.
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The following shows the conditional compilation required to load a
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bitmap under Unix and in Windows. The alternative is to use the string
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version of the bitmap constructor, which loads a file under Unix and a
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resource or file under Windows, but has the disadvantage of requiring the
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XPM icon file to be available at run-time.
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\begin{verbatim}
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#if defined(__WXGTK__) || defined(__WXMOTIF__)
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#include "mondrian.xpm"
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#endif
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\end{verbatim}
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A macro, \helpref{wxICON}{wxicon}, is available which creates an icon using an XPM
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on the appropriate platform, or an icon resource on Windows.
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\begin{verbatim}
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wxIcon icon(wxICON(mondrian));
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// Equivalent to:
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#if defined(__WXGTK__) || defined(__WXMOTIF__)
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wxIcon icon(mondrian_xpm);
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#endif
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#if defined(__WXMSW__)
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wxIcon icon("mondrian");
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#endif
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\end{verbatim}
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There is also a corresponding \helpref{wxBITMAP}{wxbitmap} macro which allows
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to create the bitmaps in much the same way as \helpref{wxICON}{wxicon} creates
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icons. It assumes that bitmaps live in resources under Windows or OS2 and XPM
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files under all other platforms (for XPMs, the corresponding file must be
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included before this macro is used, of course, and the name of the bitmap
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should be the same as the resource name under Windows with {\tt \_xpm}
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suffix). For example:
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\begin{verbatim}
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// an easy and portable way to create a bitmap
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wxBitmap bmp(wxBITMAP(bmpname));
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// which is roughly equivalent to the following
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#if defined(__WXMSW__) || defined(__WXPM__)
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wxBitmap bmp("bmpname", wxBITMAP_TYPE_RESOURCE);
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#else // Unix
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wxBitmap bmp(bmpname_xpm, wxBITMAP_TYPE_XPM);
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#endif
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\end{verbatim}
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You should always use wxICON and wxBITMAP macros because they work for any
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platform (unlike the code above which doesn't deal with wxMac, wxBe, ...) and
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are more short and clear than versions with {\tt #ifdef}s.
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\subsection{Supported bitmap file formats}\label{supportedbitmapformats}
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The following lists the formats handled on different platforms. Note
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that missing or partially-implemented formats can be supplemented
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by using \helpref{wxImage}{wximage} to load the data, and then converting
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it to wxBitmap form.
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\wxheading{wxBitmap}
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Under Windows, wxBitmap may load the following formats:
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\begin{itemize}\itemsep=0pt
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\item Windows bitmap resource (wxBITMAP\_TYPE\_BMP\_RESOURCE)
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\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
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\item PNG file (wxBITMAP\_TYPE\_PNG). Currently 4-bit (16-colour) PNG files do not load properly.
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\item XPM data and file (wxBITMAP\_TYPE\_XPM)
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\end{itemize}
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Under wxGTK, wxBitmap may load the following formats:
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\begin{itemize}\itemsep=0pt
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\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
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\item PNG (wxBITMAP\_TYPE\_PNG).
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\item XPM data and file (wxBITMAP\_TYPE\_XPM)
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\end{itemize}
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Under wxMotif, wxBitmap may load the following formats:
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\begin{itemize}\itemsep=0pt
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%\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
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%\item PNG (wxBITMAP\_TYPE\_PNG).
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\item XBM data and file (wxBITMAP\_TYPE\_XBM)
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\item XPM data and file (wxBITMAP\_TYPE\_XPM)
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\end{itemize}
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\wxheading{wxIcon}
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Under Windows, wxIcon may load the following formats:
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\begin{itemize}\itemsep=0pt
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\item Windows icon resource (wxBITMAP\_TYPE\_ICO\_RESOURCE)
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\item Windows icon file (wxBITMAP\_TYPE\_ICO)
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\item XPM data and file (wxBITMAP\_TYPE\_XPM)
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\end{itemize}
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Under wxGTK, wxIcon may load the following formats:
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\begin{itemize}\itemsep=0pt
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\item PNG (wxBITMAP\_TYPE\_PNG).
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\item XPM data and file (wxBITMAP\_TYPE\_XPM)
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\end{itemize}
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Under wxMotif, wxIcon may load the following formats:
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\begin{itemize}\itemsep=0pt
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%\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
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%\item PNG (wxBITMAP\_TYPE\_PNG).
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\item XBM data and file (wxBITMAP\_TYPE\_XBM)
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\item XPM data and file (wxBITMAP\_TYPE\_XPM)
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\end{itemize}
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\wxheading{wxCursor}
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Under Windows, wxCursor may load the following formats:
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\begin{itemize}\itemsep=0pt
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\item Windows cursor resource (wxBITMAP\_TYPE\_CUR\_RESOURCE)
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\item Windows cursor file (wxBITMAP\_TYPE\_CUR)
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\item Windows icon file (wxBITMAP\_TYPE\_ICO)
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\item Windows bitmap file (wxBITMAP\_TYPE\_BMP)
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\end{itemize}
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Under wxGTK, wxCursor may load the following formats (in additional
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to stock cursors):
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\begin{itemize}\itemsep=0pt
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\item None (stock cursors only).
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\end{itemize}
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Under wxMotif, wxCursor may load the following formats:
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\begin{itemize}\itemsep=0pt
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\item XBM data and file (wxBITMAP\_TYPE\_XBM)
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\end{itemize}
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\subsection{Bitmap format handlers}\label{bitmaphandlers}
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To provide extensibility, the functionality for loading and saving bitmap formats
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is not implemented in the wxBitmap class, but in a number of handler classes,
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derived from wxBitmapHandler. There is a static list of handlers which wxBitmap
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examines when a file load/save operation is requested. Some handlers are provided as standard, but if you
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have special requirements, you may wish to initialise the wxBitmap class with
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some extra handlers which you write yourself or receive from a third party.
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To add a handler object to wxBitmap, your application needs to include the header which implements it, and
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then call the static function \helpref{wxBitmap::AddHandler}{wxbitmapaddhandler}. For example:
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{\small
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\begin{verbatim}
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#include <wx/pnghand.h>
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#include <wx/xpmhand.h>
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...
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// Initialisation
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wxBitmap::AddHandler(new wxPNGFileHandler);
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wxBitmap::AddHandler(new wxXPMFileHandler);
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wxBitmap::AddHandler(new wxXPMDataHandler);
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...
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\end{verbatim}
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}
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Assuming the handlers have been written correctly, you should now be able to load and save PNG files
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and XPM files using the usual wxBitmap API.
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{\bf Note:} bitmap handlers are not implemented on all platforms. Currently, the above is only necessary on
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Windows, to save the extra overhead of formats that may not be necessary (if you don't use them, they
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are not linked into the executable). Unix platforms have PNG and XPM capability built-in (where supported).
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