Cocoa: distinguish input device / scrollWheel: as mouse-scroll wheel and TrackPad

问题

I am looking for a method to reliably distinguish within [NSResponder scrollWheel:] if the users input device has a one-dimensional scroll-wheel or a two dimensional trackPad/magicMouse?

In the first I would like to implement a different behavior. But just taking a look on the deltaX of the NSEvent would be a little weak. Any suggestions?

回答1:

You can use the private method call [theEvent _scrollPhase] to tell whether the device is using inertial scrolling, which indicates an Apple-supplied input device. (Note: this won't work if the user has disabled inertial scrolling)

回答2:

Use the event's subtype:

enum {
   NSMouseEventSubtype           = NX_SUBTYPE_DEFAULT,
   NSTabletPointEventSubtype     = NX_SUBTYPE_TABLET_POINT,
   NSTabletProximityEventSubtype = NX_SUBTYPE_TABLET_PROXIMITY
   NSTouchEventSubtype             = NX_SUBTYPE_MOUSE_TOUCH
};

This will work even with inertial scrolling disabled.

来源：https://stackoverflow.com/questions/5217680/cocoa-distinguish-input-device-scrollwheel-as-mouse-scroll-wheel-and-trackpa