title: Convert DrawingImage into Geometry
body: <p>I have several DrawingImages that were created in a ResourceDictionary (in a .xaml file).<br>
  I also have a 'Path', that I want to set its 'Data' property. 
  So, I want to 1) Get access to a Resource  2) Cast it to DrawingImage  3) Manipulate it to the point where I can get access to the Geometry that draws it.  4) Store that Geometry in Path.Data</p>