multi-touch-dev team mailing list archive

[Matthis R <ebaytroete@xxxxxx>]

Am 31.07.2012 17:43, schrieb Chase Douglas:
> On 07/24/2012 02:48 PM, Matthis R wrote:
> > Am 24.07.2012 23:36, schrieb Chase Douglas:
> > > On 07/24/2012 12:47 PM, Matthis R wrote:
> > > > Am 24.07.2012 20:22, schrieb Chase Douglas:
> > > > > On 07/24/2012 05:00 AM, Matthis R wrote:
> > > > > > Hello everyone,
> > > > > >
> > > > > > since I installed Ubuntu 64biz 12.04, the multitouch support for my
> > > > > > Synaptics trackpad seems to be broken.
> > > > > > When I try to "sudo mtdev-test /dev/input/event9" (which is my
> > > > > > touchpad)
> > > > > > it throws:
> > > > > > -> error: could not grab device
> > > > > >
> > > > > > Also geistest is throwing an error saying:
> > > > > > -> error subscribing to gestures
> > > > > > -> error subscribing window 0x000000b9
> > > > > >
> > > > > > Is this a known problem with synaptics pads, am I facing a bug
> > > > > > here, or
> > > > > > is it intended behaviour?
> > > > >
> > > > > Hi Matthis,
> > > > >
> > > > > There are two issues here. First, X will grab the touchpad evdev 
> > > > > node.
> > > > > This prevents mtdev-test from working. This has always been the case.
> > > > > If you want to use mtdev directly with a touchpad, you have to
> > > > > configure the X server so it doesn't grab the touchpad. There's
> > > > > instructions somewhere on wiki.ubuntu.com on how to do this, but
> > > > > generally this isn't what you want to be doing anyway.
> > > > >
> > > > > The second issue, geistest errors, is due to a change in uTouch in
> > > > > 12.04. The previous incarnation of the uTouch stack would allow for
> > > > > multiple clients to select for gestures and touches on a given 
> > > > > window.
> > > > > The new uTouch architecture, which is now built on top of the
> > > > > multitouch support in X.org, does not allow for this. While this can
> > > > > be seen as a regression in behavior, it actually better defines what
> > > > > happens when multiple clients attempt to receive touch and gesture
> > > > > events from the same window. Ideally, this shouldn't be happening.
> > > > >
> > > > > The exact error you are seeing is due to geistest by default
> > > > > attempting to subscribe to gestures on the root window. Unity already
> > > > > has a gesture subscription on the root window, so geistest fails. If
> > > > > you were to run geistest under a different environment, like KDE, it
> > > > > should succeed. What you can do instead is to run geistest on a
> > > > > specific window. You can use xwininfo to get the window ID of a
> > > > > specific window. Then you can pass that to geistest by using the "-w"
> > > > > option.
> > > > >
> > > > > You might find other tools more useful for testing, however. I 
> > > > > suggest
> > > > > trying geisview, for example.
> > > > Hey Chase.
> > > >
> > > > Thanks for your detailed answer - that really shed some light on the
> > > > dark.
> > > > With your advice geistest is now usable with the -w switch under unity
> > > > and, as you mentioned, its working ootb under gnome3.
> > > > But then again, geistest seems to have no function what so ever.
> > > >
> > > > This is the output:
> > > > http://pastebin.com/ySi8ym5v
> > > > This stays forever - even if I'd make a linedance on my touchpad ;-)
> > > > Am I missing something fundamental again?
> > > >
> > > > I'm really sorry for beeing so noobish, but I want to understand the
> > > > basics of the multitouch stuff in general for programming purposes.
> > >
> > > No worries!
> > >
> > > So there are two troublesome aspects of multitouch on touchpads:
> > >
> > > * Many are only two-touch (including poorly implemented two-touch,
> > > too). Yours falls in this group. Unfortunately, you won't be able to
> > > get any Unity gestures because they are 3 and 4 touch. You would be
> > > able to receive two touch gestures if it weren't for the next point:
> > >
> > > * Because of the legacy architecture of X.org itself, it is not
> > > possible to have traditional X scroll and multi-button emulation *and*
> > > multitouch gestures through uTouch at the same time. You will only be
> > > able to receive two-touch gestures if you go into the mouse
> > > preferences and disable "tap to click" and two finger scrolling.
> > >
> > > Hopefully the latter will be resolved when we move to a modern display
> > > server like Wayland.
> > Hm that seems strange, because before 12.04 I was able to use up to 3
> > finger gestures with ginn (I used that occasionally for
> > desktopswitching) on the very same touchpad.
> >
> > So 3 finger gestures _were_ supported - once upon a time ;-)
> > That's exactly the point I don't get.
>
> Yes, the original gesture stack had support for semi-multitouch 
> devices. These devices only give a bounding box of the touches, but 
> you don't know where each touch really is. For example, if you have 
> touches in the top left and bottom right of the touchpad it may give 
> you a bounding box with coordinates of bottom left, top right.
>
> Our original architecture was embedded inside the X display server. It 
> was a huge patch and was not able to provide for some of the more 
> advanced features we have today. When we moved to the client side of 
> X, we lost the ability to handle semi-multitouch devices. Support 
> could theoretically be added back in, but support would first have to 
> be added to the X server for semi-multitouch devices. Unfortunately, 
> this just isn't a priority at this point since many of the newest 
> trackpads support full multitouch.
>
> I'm sorry there isn't any better news :(.
Okay - at least now I have a reason to buy a new laptop :-D
But btt. thanks for the elaborate support, I really appreciate that!

Thanks!
Matthis