Instead of having a mask of pending events there is now an enum with a
single value to represent the one pending event. The event gets
flushed explicitly as part of the handling code for each event type
rather than in the outer event reading loop. The pending event is used
so that we can combine multiple motion events into one and to make
sure that we have recieved the latest position before sending a touch
up or down event. This should fix the following problems with the old
approach:
• If you release a finger and press it down again quickly you could
get the up and down events in the same batch. However the pending
events were always processed in the order down then up so it would
end up notifying two down events and then an up. The pending event
is now always flushed when there is a new up or down event so they
will always be in the right order.
• When it got a slot event it would immediately change the slot number
and then set the pending event. Then when it flushed the events it
would use the new slot number to flush the old pending event so the
events could have the wrong finger. The pending event is now
immediately flushed when a slot event is received so it will have
the right finger.
• If you get more than 32 events in one read then it was resetting the
pending events before processing the next batch in
evdev_process_events. If four fingers were pressed down at once then
it ended up with more than 32 events and the sync message would be
in the second batch. The pending flag for the last finger was
getting cleared so it never got emitted. In this patch the pending
event is no longer reset after reading nor is it explicitly flushed.
Instead it is flushed when we receive a EV_SYN event or a different
pending event needs to replace it.
The touchpad handling code was trying to use the pending event
mechanism to notify the relative motion events. I'm not sure why it
was doing this because it looks the event would effectively get
emitted as soon as the touchpad_process function is finished anyway
and it wasn't accumulating the values. Instead I've just changed it to
emit the event directly.
https://bugs.freedesktop.org/show_bug.cgi?id=67563
daf7d4774b