title: How to determine rendered size of graphics in Image Control
body: <p>I have an Image control set for Uniform stretch. It is wider than tall (landscape). I am putting a graphic (source) in it that is taller than wide (portrait). This means that the top and bottom of the graphic match the top and bottom of the Image control and there is 'dead space' on either side of the graphic. Got the picture? (pun intended)</p>
  
  <p>At this point I zoom in and out of the graphic using a Matrix.ScaleAtPrepend on the Image control and pan using Matrix.OffsetX and OffsetY.  Works great.</p>
  
  <p>Now I would like to click on the panned/zoomed graphic and get the pixel coordinates of my click relative to the graphic and not relative to the Image control.</p>
  
  <p>How might I do that?</p>