usb hid mouse calibration

Hi everyone,
I am trying to understand usb hidmouse protocol. My final aim is to move the cursor on my tft using my mouse movements. I have used usblyzer to understand the descriptors of hid. What I could not find is, my usb mouse is not giving the unit exponent field. How to find the resolution of the mouse now?? And lets say my display is 320x240 how to calibrate my mouse for this display??

Thanks !