docs/doxygen/overviews/dc.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        dc
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /*!
  10
  11  @page dc_overview Device context overview
  12
  13  Classes: #wxBufferedDC, #wxBufferedPaintDC, #wxDC, #wxPostScriptDC,
  14  #wxMetafileDC, #wxMemoryDC, #wxPrinterDC,
  15  #wxScreenDC, #wxClientDC, #wxPaintDC,
  16  #wxWindowDC.
  17  A wxDC is a @e device context onto which graphics and text can be drawn.
  18  The device context is intended to represent a number of output devices in a generic way,
  19  with the same API being used throughout.
  20  Some device contexts are created temporarily in order to draw on a window.
  21  This is @true of #wxScreenDC, #wxClientDC, #wxPaintDC,
  22  and #wxWindowDC. The following describes the differences between
  23  these device contexts and when you should use them.
  24
  25
  26   @b wxScreenDC. Use this to paint on the screen, as opposed to an individual window.
  27   @b wxClientDC. Use this to paint on the client area of window (the part without
  28  borders and other decorations), but do not use it from within an #wxPaintEvent.
  29   @b wxPaintDC. Use this to paint on the client area of a window, but @e only from
  30  within a #wxPaintEvent.
  31   @b wxWindowDC. Use this to paint on the whole area of a window, including decorations.
  32  This may not be available on non-Windows platforms.
  33
  34
  35  To use a client, paint or window device context, create an object on the stack with
  36  the window as argument, for example:
  37
  38  @code
  39  void MyWindow::OnMyCmd(wxCommandEvent& event)
  40    {
  41      wxClientDC dc(window);
  42      DrawMyPicture(dc);
  43    }
  44  @endcode
  45
  46  Try to write code so it is parameterised by wxDC - if you do this, the same piece of code may
  47  write to a number of different devices, by passing a different device context. This doesn't
  48  work for everything (for example not all device contexts support bitmap drawing) but
  49  will work most of the time.
  50
  51  */
  52
  53