Camera Capture using TextureView. Need Tap on Focus.

I had implemented a custom page renderer to show the camera view using TextureView.ISurfaceTextureListener. When capturing the tiny objects, the auto focus is not functioning well, and is blurred continuously . used the below parameters to set the continuous focus mode.

Is there anyway to implement 'Tap on Focus' kind of logic in this page renderer, so that the user can focus on required object. If possible, any sample piece of code would be great help.

Code used for auto-focus:
Android.Hardware.Camera.Parameters parameters = camera.GetParameters();
parameters.FocusMode = global::Android.Hardware.Camera.Parameters.FocusModeContinuousPicture;
camera.SetParameters(parameters);