docs/doxygen/overviews/dc.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        dc.h
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /*!
  10
  11  @page overview_dc Device context overview
  12
  13  Classes: #wxBufferedDC, #wxBufferedPaintDC, #wxDC, #wxPostScriptDC,
  14           #wxMetafileDC, #wxMemoryDC, #wxPrinterDC, #wxScreenDC, #wxClientDC,
  15           #wxPaintDC, #wxWindowDC.
  16
  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
  19  generic way, with the same API being used throughout.
  20
  21  Some device contexts are created temporarily in order to draw on a window.
  22  This is @true of #wxScreenDC, #wxClientDC, #wxPaintDC, and #wxWindowDC.
  23  The following describes the differences between these device contexts and
  24  when you should use them.
  25
  26  @li @b wxScreenDC. Use this to paint on the screen, as opposed to an individual window.
  27  @li @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  @li @b wxPaintDC. Use this to paint on the client area of a window, but @e only from
  30      within a #wxPaintEvent.
  31  @li @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  To use a client, paint or window device context, create an object on the stack with
  35  the window as argument, for example:
  36
  37  @code
  38    void MyWindow::OnMyCmd(wxCommandEvent& event)
  39    {
  40      wxClientDC dc(window);
  41      DrawMyPicture(dc);
  42    }
  43  @endcode
  44
  45  Try to write code so it is parameterised by wxDC - if you do this, the same piece of code may
  46  write to a number of different devices, by passing a different device context. This doesn't
  47  work for everything (for example not all device contexts support bitmap drawing) but
  48  will work most of the time.
  49
  50 */
  51