As prior commit, but complete fix for XBox controller and trigger
buttons too.

> The joystick range is a float from -1 through +1. Casting this to int
> yields only three possible values: -1, 0, and 1. This gives a
> misleading joystick placement in the demo.
>
> By casting to int after the multiplication to get pixel values, the
> demo reveals the analog feel of the joystick.