added images for topic overviews

[wxWidgets.git] / docs / doxygen / overviews / bitmap.h

/////////////////////////////////////////////////////////////////////////////
// Name:        bitmap.h
// Purpose:     topic overview
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/*!

 @page overview_bitmap Bitmaps and icons overview

 Classes: #wxBitmap, #wxBitmapHandler, #wxIcon, #wxCursor.

 The wxBitmap class encapsulates the concept of a platform-dependent bitmap,
 either monochrome or colour. Platform-specific methods for creating a
 wxBitmap object from an existing file are catered for, and
 this is an occasion where conditional compilation will sometimes be
 required.

 A bitmap created dynamically or loaded from a file can be selected
 into a memory device context (instance of #wxMemoryDC). This
 enables the bitmap to be copied to a window or memory device context
 using wxDC::Blit, or to be used as a drawing surface.

 See #wxMemoryDC for an example of drawing onto a bitmap.

 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.

 @code
 #include "mondrian.xpm"
 @endcode

 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, #wxICON, is available which creates an icon using an XPM
 on the appropriate platform, or an icon resource on Windows.

 @code
 wxIcon icon(wxICON(mondrian));

 // Equivalent to:

 #if defined(__WXGTK__) || defined(__WXMOTIF__)
 wxIcon icon(mondrian_xpm);
 #endif

 #if defined(__WXMSW__)
 wxIcon icon("mondrian");
 #endif
 @endcode

 There is also a corresponding #wxBITMAP macro which allows
 to create the bitmaps in much the same way as #wxICON 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 @c _xpm
 suffix). For example:

 @code
 // 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
 @endcode

 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 @c #ifdefs. Even better,
 use the same XPMs on all platforms.

 @li @ref overview_bitmap_supportedformats
 @li @ref overview_bitmap_handlers


 <hr>


 @section overview_bitmap_supportedformats Supported bitmap file formats

 The following lists the formats handled on different platforms. Note
 that missing or partially-implemented formats are automatically supplemented
 by the #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.

 @b wxBitmap
 Under Windows, wxBitmap may load the following formats:

  @li Windows bitmap resource (wxBITMAP_TYPE_BMP_RESOURCE)
  @li Windows bitmap file (wxBITMAP_TYPE_BMP)
  @li XPM data and file (wxBITMAP_TYPE_XPM)
  @li All formats that are supported by the #wxImage class.

 Under wxGTK, wxBitmap may load the following formats:

  @li XPM data and file (wxBITMAP_TYPE_XPM)
  @li All formats that are supported by the #wxImage class.

 Under wxMotif and wxX11, wxBitmap may load the following formats:

  @li XBM data and file (wxBITMAP_TYPE_XBM)
  @li XPM data and file (wxBITMAP_TYPE_XPM)
  @li All formats that are supported by the #wxImage class.


 @b wxIcon
 Under Windows, wxIcon may load the following formats:

  @li Windows icon resource (wxBITMAP_TYPE_ICO_RESOURCE)
  @li Windows icon file (wxBITMAP_TYPE_ICO)
  @li XPM data and file (wxBITMAP_TYPE_XPM)

 Under wxGTK, wxIcon may load the following formats:

  @li XPM data and file (wxBITMAP_TYPE_XPM)
  @li All formats that are supported by the #wxImage class.

 Under wxMotif and wxX11, wxIcon may load the following formats:

  @li XBM data and file (wxBITMAP_TYPE_XBM)
  @li XPM data and file (wxBITMAP_TYPE_XPM)
  @li All formats that are supported by the #wxImage class.


 @b wxCursor
 Under Windows, wxCursor may load the following formats:

  @li Windows cursor resource (wxBITMAP_TYPE_CUR_RESOURCE)
  @li Windows cursor file (wxBITMAP_TYPE_CUR)
  @li Windows icon file (wxBITMAP_TYPE_ICO)
  @li Windows bitmap file (wxBITMAP_TYPE_BMP)

 Under wxGTK, wxCursor may load the following formats (in additional
 to stock cursors):

  @li None (stock cursors only).

 Under wxMotif and wxX11, wxCursor may load the following formats:

  @li XBM data and file (wxBITMAP_TYPE_XBM)



 @section overview_bitmap_handlers Bitmap format handlers

 To provide extensibility, the functionality for loading and saving bitmap formats
 is not implemented in the wxBitmap class, but in a number of handler classes,
 derived from wxBitmapHandler. There is a static list of handlers which wxBitmap
 examines when a file load/save operation is requested. 

 Some handlers are provided as standard, but if you
 have special requirements, you may wish to initialise the wxBitmap class with
 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 wxBitmap::AddHandler.

 @b 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.

*/