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<div class="title">Device Contexts </div> </div>
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<div class="textblock"><p>A <a class="el" href="classwx_d_c.html" title="A wxDC is a "device context" onto which graphics and text can be drawn.">wxDC</a> is a <em>device</em> context onto which graphics and text can be drawn.</p>
<p>The device context is intended to represent a number of output devices in a generic way, with the same API being used throughout.</p>
<p>Some device contexts are created temporarily in order to draw on a window. This is <span class="literal">true</span> of <a class="el" href="classwx_screen_d_c.html" title="A wxScreenDC can be used to paint on the screen.">wxScreenDC</a>, <a class="el" href="classwx_client_d_c.html" title="A wxClientDC must be constructed if an application wishes to paint on the client area of a window fro...">wxClientDC</a>, <a class="el" href="classwx_paint_d_c.html" title="A wxPaintDC must be constructed if an application wishes to paint on the client area of a window from...">wxPaintDC</a>, and <a class="el" href="classwx_window_d_c.html" title="A wxWindowDC must be constructed if an application wishes to paint on the whole area of a window (cli...">wxWindowDC</a>. The following describes the differences between these device contexts and when you should use them.</p>
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<li><b><a class="el" href="classwx_screen_d_c.html" title="A wxScreenDC can be used to paint on the screen.">wxScreenDC</a></b>. Use this to paint on the screen, as opposed to an individual window. </li>
<li><b><a class="el" href="classwx_client_d_c.html" title="A wxClientDC must be constructed if an application wishes to paint on the client area of a window fro...">wxClientDC</a></b>. Use this to paint on the client area of window (the part without borders and other decorations), but do not use it from within an <a class="el" href="classwx_paint_event.html" title="A paint event is sent when a window's contents needs to be repainted.">wxPaintEvent</a>. </li>
<li><b><a class="el" href="classwx_paint_d_c.html" title="A wxPaintDC must be constructed if an application wishes to paint on the client area of a window from...">wxPaintDC</a></b>. Use this to paint on the client area of a window, but <em>only</em> from within a <a class="el" href="classwx_paint_event.html" title="A paint event is sent when a window's contents needs to be repainted.">wxPaintEvent</a>. </li>
<li><b><a class="el" href="classwx_window_d_c.html" title="A wxWindowDC must be constructed if an application wishes to paint on the whole area of a window (cli...">wxWindowDC</a></b>. Use this to paint on the whole area of a window, including decorations. This may not be available on non-Windows platforms.</li>
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<p>To use a client, paint or window device context, create an object on the stack with the window as argument, for example:</p>
<div class="fragment"><div class="line"><span class="keywordtype">void</span> MyWindow::OnMyCmd(<a class="code" href="classwx_command_event.html" title="This event class contains information about command events, which originate from a variety of simple ...">wxCommandEvent</a>& event)</div>
<div class="line">{</div>
<div class="line"> <a class="code" href="classwx_client_d_c.html" title="A wxClientDC must be constructed if an application wishes to paint on the client area of a window fro...">wxClientDC</a> dc(window);</div>
<div class="line"> DrawMyPicture(dc);</div>
<div class="line">}</div>
</div><!-- fragment --><p>Try to write code so it is parameterised by <a class="el" href="classwx_d_c.html" title="A wxDC is a "device context" onto which graphics and text can be drawn.">wxDC</a> - if you do this, the same piece of code may write to a number of different devices, by passing a different device context. This doesn't work for everything (for example not all device contexts support bitmap drawing) but will work most of the time.</p>
<dl class="section see"><dt>See Also</dt><dd><a class="el" href="group__group__class__dc.html">Device Contexts</a> </dd></dl>
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