onPan animation based on pan distance

[acegreen]

Hi,

I would like to adjust the view based on the view "infront" of it. Basically using the thresholdRatio. I want to grow the back view to the size of the front view as you pan. I am able to move it in X or Y but can't seem to crack the logic

Inputs:
frontView.frame
backView.frame
thresholdRatio