iPhone/iPad circular intensity gauge control (image included)
I found this interesting interface(starts at 33 seconds [http://vimeo.com/22946428][1] ), and would like to design something similar for my own apps. I'm particularly interested in the **circular intensity gauge/knob control as on the attached image.** 
It has a very futuristic feel to it and should be fairly simple to implement using touchesMoved: gesture recognizer callback. 

But in order to not-reinvent the wheel, are there any open source libraries that offer advanced UI capabilities, like the ones in the picture/video?


![Intensity gauge][2]


  [1]: http://vimeo.com/22946428
  [2]: http://i.stack.imgur.com/ydrAL.png
iPhone/iPad circular intensity gauge control (image included)
===

I found this interesting interface(starts at 33 seconds [http://vimeo.com/22946428][1] ), and would like to design something similar for my own apps. I'm particularly interested in the **circular intensity gauge/knob control as on the attached image.** 
It has a very futuristic feel to it and should be fairly simple to implement using touchesMoved: gesture recognizer callback. 

But in order to not-reinvent the wheel, are there any open source libraries that offer advanced UI capabilities, like the ones in the picture/video?


![Intensity gauge][2]


  [1]: http://vimeo.com/22946428
  [2]: http://i.stack.imgur.com/ydrAL.png