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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 A wxDC is a @e device context onto which graphics and text can be drawn.
14 The device context is intended to represent a number of output devices in a
15 generic way, with the same API being used throughout.
16
17 Some device contexts are created temporarily in order to draw on a window.
18 This is @true of wxScreenDC, wxClientDC, wxPaintDC, and wxWindowDC.
19 The following describes the differences between these device contexts and
20 when you should use them.
21
22 @li @b wxScreenDC. Use this to paint on the screen, as opposed to an individual window.
23 @li @b wxClientDC. Use this to paint on the client area of window (the part without
24 borders and other decorations), but do not use it from within an wxPaintEvent.
25 @li @b wxPaintDC. Use this to paint on the client area of a window, but @e only from
26 within a wxPaintEvent.
27 @li @b wxWindowDC. Use this to paint on the whole area of a window, including decorations.
28 This may not be available on non-Windows platforms.
29
30 To use a client, paint or window device context, create an object on the stack with
31 the window as argument, for example:
32
33 @code
34 void MyWindow::OnMyCmd(wxCommandEvent& event)
35 {
36 wxClientDC dc(window);
37 DrawMyPicture(dc);
38 }
39 @endcode
40
41 Try to write code so it is parameterised by wxDC - if you do this, the same piece of code may
42 write to a number of different devices, by passing a different device context. This doesn't
43 work for everything (for example not all device contexts support bitmap drawing) but
44 will work most of the time.
45
46 @see @ref group_class_dc
47
48 */