title: Getting a DrawingContext for a wpf WriteableBitmap
body: <p>Is there a way to get a <code>DrawingContext</code> (or something similar) for a <code>WriteableBitmap</code>?  I.e. something to allow you to call simple <code>DrawLine</code>/<code>DrawRectangle</code>/etc kinds of methods, rather than manipulate the raw pixels directly.</p>