code: protected void calculatePointerAngle() {
          float progressPercent = ((float) mProgress / (float) mMax);
          mPointerPosition = (progressPercent * mTotalCircleDegrees) + mStartAngle;
          mPointerPosition = mPointerPosition % 360f;
      }
docs: Calculate the pointer position (and the end of the progress arc) in degrees.
  Sets mPointerPosition to that value.