Previously we pretended that there is only one touch device; but in fact,
different trackpads have different deviceIDs, and this may be useful
in some scenarios to tell them apart, as on other platforms.
So far we don't expect to get touch events from actual touchscreens
though, because macOS only turns single-touch events into mouse events
and does not interpret gestures on touchscreens. So there isn't API
which can distinguish touchscreens from touchpads as far as we know.
QCocoaTouch::getTouchDevice() takes the type as a parameter, just in
case this changes some day.
Change-Id: I56228471363235c5d0cc2a55a35a3c3288f3b1a1
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
aa4ff7b2e9