Axis constant: X axis of a motion event.

• For a touch screen, reports the absolute X screen position of the center of the touch contact area. The units are display pixels.
• For a touch pad, reports the absolute X surface position of the center of the touch contact area. The units are device-dependent; use InputDevice.GetMotionRange(Axis) to query the effective range of values.
• For a mouse, reports the absolute X screen position of the mouse pointer. The units are display pixels.
• For a trackball, reports the relative horizontal displacement of the trackball. The value is normalized to a range from -1.0 (left) to 1.0 (right).
• For a joystick, reports the absolute X position of the joystick. The value is normalized to a range from -1.0 (left) to 1.0 (right).