38b5b4938f
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52256 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
184 lines
6.2 KiB
C
184 lines
6.2 KiB
C
/////////////////////////////////////////////////////////////////////////////
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// Name: bitmap.h
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// Purpose: topic overview
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// Author: wxWidgets team
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// RCS-ID: $Id$
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// Licence: wxWindows license
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/////////////////////////////////////////////////////////////////////////////
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/*!
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@page overview_bitmap Bitmaps and icons overview
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Classes: wxBitmap, wxBitmapHandler, wxIcon, 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 wxMemoryDC). This
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enables the bitmap to be copied to a window or memory device context
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using wxDC::Blit, or to be used as a drawing surface.
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See wxMemoryDC for an example of drawing onto a bitmap.
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All wxWidgets platforms support XPMs for small bitmaps and icons.
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You may include the XPM inline as below, since it's C code, or you
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can load it at run-time.
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@code
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#include "mondrian.xpm"
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@endcode
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Sometimes you wish to use a .ico resource on Windows, and XPMs on
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other platforms (for example to take advantage of Windows' support for
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multiple icon resolutions).
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A macro, #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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@code
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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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@endcode
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There is also a corresponding #wxBITMAP macro which allows
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to create the bitmaps in much the same way as #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 @c _xpm
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suffix). For example:
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@code
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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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@endcode
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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, wxX11, ...) and
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are shorter and more clear than versions with many @ifdef_ blocks. Even better,
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use the same XPMs on all platforms.
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@li @ref overview_bitmap_supportedformats
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@li @ref overview_bitmap_handlers
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<hr>
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@section overview_bitmap_supportedformats Supported bitmap file formats
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The following lists the formats handled on different platforms. Note
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that missing or partially-implemented formats are automatically supplemented
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by the wxImage to load the data, and then converting
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it to wxBitmap form. Note that using wxImage is the preferred way to
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load images in wxWidgets, with the exception of resources (XPM-files or
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native Windows resources).
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Writing an image format handler for wxImage is also far easier than writing
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one for wxBitmap, because wxImage has exactly one format on all platforms
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whereas wxBitmap can store pixel data very differently, depending on colour
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depths and platform.
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@subsection overview_bitmap_supportedformats_bmp wxBitmap
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Under Windows, wxBitmap may load the following formats:
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@li Windows bitmap resource (wxBITMAP_TYPE_BMP_RESOURCE)
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@li Windows bitmap file (wxBITMAP_TYPE_BMP)
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@li XPM data and file (wxBITMAP_TYPE_XPM)
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@li All formats that are supported by the wxImage class.
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Under wxGTK, wxBitmap may load the following formats:
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@li XPM data and file (wxBITMAP_TYPE_XPM)
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@li All formats that are supported by the wxImage class.
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Under wxMotif and wxX11, wxBitmap may load the following formats:
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@li XBM data and file (wxBITMAP_TYPE_XBM)
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@li XPM data and file (wxBITMAP_TYPE_XPM)
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@li All formats that are supported by the wxImage class.
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@subsection overview_bitmap_supportedformats_icon wxIcon
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Under Windows, wxIcon may load the following formats:
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@li Windows icon resource (wxBITMAP_TYPE_ICO_RESOURCE)
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@li Windows icon file (wxBITMAP_TYPE_ICO)
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@li XPM data and file (wxBITMAP_TYPE_XPM)
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Under wxGTK, wxIcon may load the following formats:
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@li XPM data and file (wxBITMAP_TYPE_XPM)
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@li All formats that are supported by the wxImage class.
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Under wxMotif and wxX11, wxIcon may load the following formats:
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@li XBM data and file (wxBITMAP_TYPE_XBM)
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@li XPM data and file (wxBITMAP_TYPE_XPM)
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@li All formats that are supported by the wxImage class.
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@subsection overview_bitmap_supportedformats_cursor wxCursor
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Under Windows, wxCursor may load the following formats:
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@li Windows cursor resource (wxBITMAP_TYPE_CUR_RESOURCE)
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@li Windows cursor file (wxBITMAP_TYPE_CUR)
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@li Windows icon file (wxBITMAP_TYPE_ICO)
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@li Windows bitmap file (wxBITMAP_TYPE_BMP)
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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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@li None (stock cursors only).
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Under wxMotif and wxX11, wxCursor may load the following formats:
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@li XBM data and file (wxBITMAP_TYPE_XBM)
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@section overview_bitmap_handlers Bitmap format handlers
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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.
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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
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which implements it, and then call the static function wxBitmap::AddHandler.
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@note bitmap handlers are not implemented on all platforms, and new ones rarely need
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to be implemented since wxImage can be used for loading most formats, as noted
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earlier.
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*/
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