اختبار الأجهزة الخاصة بك دائرة نصف قطرها اللمس.
This app graphs the touch major/minor radii, and pressure values received from one touch. As you can see from the screen shot on my phone the touch major & minor radius are the same values, and pressure follows along the sizes.
You can use this to see how your phone/hardware supports interpreting these values.