a gamepad.
a touchpad.
a finger.
a pointer filled with true if the finger is down, false otherwise, may be NULL.
a pointer filled with the x position, normalized 0 to 1, with the origin in the upper left, may be NULL.
a pointer filled with the y position, normalized 0 to 1, with the origin in the upper left, may be NULL.
a pointer filled with pressure value, may be NULL.
true on success or false on failure; call SDL_GetError() for more information.
Get the current state of a finger on a touchpad on a gamepad.