Camera Overlay - Xamarin Forms

Hello,

i've been working on the sample provided by XLabs to work with the camera ( https://github.com/XLabs/Xamarin-Forms-Labs/wiki/Camera ) and its working ok (only if target API = 21) .

I wanted to know if its possible to Overlay the camera menu, the purpose is to add a rectangule to the screen. I know how to do it in Objective-C , but how would I implement it on Xamarin ? (for android and iOS)

Thanks in advance !