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 licence
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10
  11 @page overview_dc Device Contexts
  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