title: How to get Stream/PathGeometry that's outline of geometry 'widened' with Pen stroke in WPF?
body: <p>This is quite hard for me to explain so I'll use an image as example:
  <img src="https://i.stack.imgur.com/PpL7n.png" alt="enter image description here"><br>
  I have defined a StreamGeometry (in code).<br>
  When it is drawn with <code>DrawingContext.DrawGeometry</code> using both Brush to fill and Pen to stroke, the geometry is 'widened' by the Pen Thickness.<br>
  Now I'm trying to find if there is a function in WPF that can return this solid widened geometry (in any Geometry format).</p>
  
  <p>So far I tried <code>Geometry.GetWidenedPathGeometry</code> but that only returns geometry that 'outlines' the border Pen stroke. It has a hole where the fill should be.</p>
  
  <p>I guess I can use <code>GetWidenedPathGeometry</code> and do some sort of Union with the original geometry, 'filling' the hole. I just want to be sure there isn't an easier or <strong>more effective</strong> (faster) way.<br>
  Also it would be preferable if the geometry can stay a StreamGeometry, but <code>GetWidenedPathGeometry</code> converts it into (somehow mangled ?) PathGeometry.</p>
  
  <p>Thanks for any advice</p>