title: Union of adjacent shapes in C#/WPF
body: <p>I'm using a <code>CombinedGeometry</code> in C# to join several polygons together.</p>
  
  <p>The <code>RenderedGeometry</code> of each shape is taken, and joined to the final shape with <code>GeometryCombineMode.Union</code>.</p>
  
  <p>However, I'm having a problem where two shapes are adjacent, but not overlapping (a 0px gap between the two). As they do not overlap, they will not be joined by the <code>CombinedGeometry</code>.</p>
  
  <p>I've considered enlarging each input shape by 1 pixel, then contracting the output by the same, but this can't be done accurately using a <code>ScaleTransform</code>.</p>
  
  <p>How can I join these two shapes together?</p>