I've been working on a Silverlight 1.0 sample that I'd like to share with you for two reasons:

  1. I think it's a great application of the VideoBrush feature in Silverlight which enables you to route video to any shape's stroke or fill.
  2. I need a little bit of help with the math to get the zooming right.

The sample which you can see here is a magnifying glass that zooms in on whatever portion of a playing video that it's over.  This effect is done through using the VideoBrush in Silverlight 1.0.  Typically you would hide the source MediaElement for the VideoBrush, but in this case I wanted to show both.  By doing that I keep the two videos in synch.

I plan on submitting this sample to the gallery on but I need to get some of the math right when you zoom in/out the magnifier.  You will notice that the center is not correct once you rotate the zoom lever. 

What are the applications of this technique:

  1. Add a magnifier to any Silverlight application that uses video
  2. Change the brush shape from a circle to a binocular shape.
  3. Hunting game

Upcoming Webinar

On Friday February 15, 2008 at 10:00 PDT, I will be hosting a free webinar where I will explain how I built this demo. Register here.  It will be recorded if you cannot make the live event.

Source Code

I have attached the source code to this Post (without the Bear.wmv video - it comes with Windows Vista in the Sample Videos folder).

Some Math Help Please

If you like this demo, and are good at math, I need your help.  If you rotate the zoom handle you will notice that the magnified video gets offset incorrectly.  I would love any help the Silverlight community would like to offer to help me with my math to get it right.