docs/doxygen/overviews/bitmap.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        bitmap.h
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /*!
  10
  11  @page overview_bitmap Bitmaps and icons overview
  12
  13  Classes: wxBitmap, wxBitmapHandler, wxIcon, wxCursor.
  14
  15  The wxBitmap class encapsulates the concept of a platform-dependent bitmap,
  16  either monochrome or colour. Platform-specific methods for creating a
  17  wxBitmap object from an existing file are catered for, and
  18  this is an occasion where conditional compilation will sometimes be
  19  required.
  20
  21  A bitmap created dynamically or loaded from a file can be selected
  22  into a memory device context (instance of wxMemoryDC). This
  23  enables the bitmap to be copied to a window or memory device context
  24  using wxDC::Blit, or to be used as a drawing surface.
  25
  26  See wxMemoryDC for an example of drawing onto a bitmap.
  27
  28  All wxWidgets platforms support XPMs for small bitmaps and icons.
  29  You may include the XPM inline as below, since it's C code, or you
  30  can load it at run-time.
  31
  32  @code
  33  #include "mondrian.xpm"
  34  @endcode
  35
  36  Sometimes you wish to use a .ico resource on Windows, and XPMs on
  37  other platforms (for example to take advantage of Windows' support for
  38  multiple icon resolutions).
  39
  40  A macro, #wxICON, is available which creates an icon using an XPM
  41  on the appropriate platform, or an icon resource on Windows.
  42
  43  @code
  44  wxIcon icon(wxICON(mondrian));
  45
  46  // Equivalent to:
  47
  48  #if defined(__WXGTK__) || defined(__WXMOTIF__)
  49  wxIcon icon(mondrian_xpm);
  50  #endif
  51
  52  #if defined(__WXMSW__)
  53  wxIcon icon("mondrian");
  54  #endif
  55  @endcode
  56
  57  There is also a corresponding #wxBITMAP macro which allows
  58  to create the bitmaps in much the same way as #wxICON creates
  59  icons. It assumes that bitmaps live in resources under Windows or OS2 and XPM
  60  files under all other platforms (for XPMs, the corresponding file must be
  61  included before this macro is used, of course, and the name of the bitmap
  62  should be the same as the resource name under Windows with @c _xpm
  63  suffix). For example:
  64
  65  @code
  66  // an easy and portable way to create a bitmap
  67  wxBitmap bmp(wxBITMAP(bmpname));
  68
  69  // which is roughly equivalent to the following
  70  #if defined(__WXMSW__) || defined(__WXPM__)
  71      wxBitmap bmp("bmpname", wxBITMAP_TYPE_RESOURCE);
  72  #else // Unix
  73      wxBitmap bmp(bmpname_xpm, wxBITMAP_TYPE_XPM);
  74  #endif
  75  @endcode
  76
  77  You should always use wxICON and wxBITMAP macros because they work for any
  78  platform (unlike the code above which doesn't deal with wxMac, wxX11, ...) and
  79  are more short and clear than versions with @c #ifdefs. Even better,
  80  use the same XPMs on all platforms.
  81
  82  @li @ref overview_bitmap_supportedformats
  83  @li @ref overview_bitmap_handlers
  84
  85
  86  <hr>
  87
  88
  89  @section overview_bitmap_supportedformats Supported bitmap file formats
  90
  91  The following lists the formats handled on different platforms. Note
  92  that missing or partially-implemented formats are automatically supplemented
  93  by the wxImage to load the data, and then converting
  94  it to wxBitmap form. Note that using wxImage is the preferred way to
  95  load images in wxWidgets, with the exception of resources (XPM-files or
  96  native Windows resources).
  97
  98  Writing an image format handler for wxImage is also far easier than writing
  99  one for wxBitmap, because wxImage has exactly one format on all platforms
 100  whereas wxBitmap can store pixel data very differently, depending on colour
 101  depths and platform.
 102
 103  @subsection overview_bitmap_supportedformats_bmp wxBitmap
 104
 105  Under Windows, wxBitmap may load the following formats:
 106
 107   @li Windows bitmap resource (wxBITMAP_TYPE_BMP_RESOURCE)
 108   @li Windows bitmap file (wxBITMAP_TYPE_BMP)
 109   @li XPM data and file (wxBITMAP_TYPE_XPM)
 110   @li All formats that are supported by the wxImage class.
 111
 112  Under wxGTK, wxBitmap may load the following formats:
 113
 114   @li XPM data and file (wxBITMAP_TYPE_XPM)
 115   @li All formats that are supported by the wxImage class.
 116
 117  Under wxMotif and wxX11, wxBitmap may load the following formats:
 118
 119   @li XBM data and file (wxBITMAP_TYPE_XBM)
 120   @li XPM data and file (wxBITMAP_TYPE_XPM)
 121   @li All formats that are supported by the wxImage class.
 122
 123
 124  @subsection overview_bitmap_supportedformats_icon wxIcon
 125
 126  Under Windows, wxIcon may load the following formats:
 127
 128   @li Windows icon resource (wxBITMAP_TYPE_ICO_RESOURCE)
 129   @li Windows icon file (wxBITMAP_TYPE_ICO)
 130   @li XPM data and file (wxBITMAP_TYPE_XPM)
 131
 132  Under wxGTK, wxIcon may load the following formats:
 133
 134   @li XPM data and file (wxBITMAP_TYPE_XPM)
 135   @li All formats that are supported by the wxImage class.
 136
 137  Under wxMotif and wxX11, wxIcon may load the following formats:
 138
 139   @li XBM data and file (wxBITMAP_TYPE_XBM)
 140   @li XPM data and file (wxBITMAP_TYPE_XPM)
 141   @li All formats that are supported by the wxImage class.
 142
 143
 144  @subsection overview_bitmap_supportedformats_cursor wxCursor
 145
 146  Under Windows, wxCursor may load the following formats:
 147
 148   @li Windows cursor resource (wxBITMAP_TYPE_CUR_RESOURCE)
 149   @li Windows cursor file (wxBITMAP_TYPE_CUR)
 150   @li Windows icon file (wxBITMAP_TYPE_ICO)
 151   @li Windows bitmap file (wxBITMAP_TYPE_BMP)
 152
 153  Under wxGTK, wxCursor may load the following formats (in additional
 154  to stock cursors):
 155
 156   @li None (stock cursors only).
 157
 158  Under wxMotif and wxX11, wxCursor may load the following formats:
 159
 160   @li XBM data and file (wxBITMAP_TYPE_XBM)
 161
 162
 163
 164  @section overview_bitmap_handlers Bitmap format handlers
 165
 166  To provide extensibility, the functionality for loading and saving bitmap formats
 167  is not implemented in the wxBitmap class, but in a number of handler classes,
 168  derived from wxBitmapHandler. There is a static list of handlers which wxBitmap
 169  examines when a file load/save operation is requested.
 170
 171  Some handlers are provided as standard, but if you
 172  have special requirements, you may wish to initialise the wxBitmap class with
 173  some extra handlers which you write yourself or receive from a third party.
 174
 175  To add a handler object to wxBitmap, your application needs to include the header
 176  which implements it, and then call the static function wxBitmap::AddHandler.
 177
 178  @note bitmap handlers are not implemented on all platforms, and new ones rarely need
 179        to be implemented since wxImage can be used for loading most formats, as noted
 180        earlier.
 181
 182 */
 183