It's looking strongly like a bug in the OS or trackpad driver, and it appears
that the additional unexpected events, while odd, are not a direct cause of the
bug I have.
I'm responding to 4 event types: LDown, LUp, LDragged and Moved.
I expect Down-Dragged-Up-Moved-Down-Dragged-Up-Moved, etc. which is what I get
reliably from a mouse.
With the trackpad, I also get this most of the time, but sometimes it goes
directly from moved to dragged without a mouse down, and vice versa sometimes
with and without a mouse up.
e.g. Down-Dragged-Up-Moved-Dragged-Moved-Dragged-Up-Moved...
The missing mouse-downs are a problem because my code uses that to advance the
state of a state machine, and because that's not happening it isn't working
properly. There is a very distinct click of the trackpad's button, but no
mouse-down gets delivered. The "dragging finger" generally remains on the
trackpad while I click or release the trackpad's mouse button. Again, this
seems incorrect to me - the button clicking should ALWAYS send a mouse down and
mouse up no matter what other fingers are doing.
I have turned off all the fancy gesture detection in system prefs, but that
made no difference.
This is very frustrating because there's probably little I can do in my code to
workaround this. I'm going to try setting a flag that means "expect a mouse
down" and if I get a drag instead, treat the first drag event as a mouse down.
That might work around it but it's pretty poor that the system really isn't
working as it should.
Surely others have noticed this? I would have thought mouse downs going missing
in a view would be a pretty obvious bug.
--Graham
On 07/11/2012, at 11:08 AM, Graham Cox <graham....@bigpond.com> wrote:
> Hi all,
>
> Following up on a problem I was having a week or so back with receiving
> multiple mouse-ups in an event loop, I've narrowed the problem down to the
> events coming from a trackpad instead of a mouse.
>
> Here's an odd thing:
>
> NSUInteger mask = NSLeftMouseDownMask | NSLeftMouseUpMask |
> NSLeftMouseDraggedMask | NSMouseMovedMask | NSScrollWheelMask | NSKeyDownMask;
> while( loop )
> {
> theEvent = [NSApp nextEventMatchingMask:mask untilDate:[NSDate
> distantFuture] inMode:NSEventTrackingRunLoopMode dequeue:YES];
>
>
> This is the fragment of code that sets up the mask and grabs the event. I
> should only get those events that match the mask, right? With a mouse, I do,
> but with a trackpad I'm also getting right mouse down, right mouse dragged
> and right mouse up returned. Is that expected? It seems incorrect.
>
> I'm not sure it has a bearing on my bug because I do ignore those events, but
> OTOH, the bug is only manifest using the trackpad. (Debugging this in the
> debugger is impossible due to the dynamic nature of the loop, so I'm having
> to try and log output at key points).
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