evdev is not compatible to QT-applications when using tablets

Bug #721471 reported by Stefan Koch on 2011-02-18
This bug affects 3 people
Affects Status Importance Assigned to Milestone
qt4-x11 (Ubuntu)

Bug Description

Binary package hint: xserver-xorg-input-evdev


evdev has the problem that it is not compatible to QT-Applications, I have tested this with a self-programmed software.
Tested this in kubuntu 11.04 daily build (2011-02-18).
I think QT-Applications like Krita, ... doesn't work, too (based on previous experience)

evdev is not compatible to the QTabletEvent from QT, see here:

See here, too, there is described that it works with WIZARDPEN-driver in ubuntu 9.10 but doesn't work in 10.10: http://ubuntuforums.org/showthread.php?t=1597558

9.10 config works (with WIZARDPEN) with setting device name to "stylus" in 9.10
with that line: <merge key="info.product" type="string">stylus</merge> in hal-config of wizardpen

I'm using the wacom driver for my Genius G-Pen F610 tablet. This work's fine.
But there are other tablets have perhaps a need for the evdev driver - I don't know.
With kubuntu 11.04 daily-build (2011-02-18) now my tablet works fine in GTK-applications (in (k)ubuntu 10.10 evdev doesn't work fine - see ubuntuforums link (click event when only moveing the stylus)).

How long it does until the much tablet drivers: wizardpen, aiptek, evdev and wacom are going into one driver (a.e. the wacom driver)?
It clould be that X11 could be replaced by Wayland, that you have heared - I think.
I dont't know if this too much of work (making evdev working with QT), if X11 will replaced to Wayland or the much tablet drivers going into one.

Best regard and thanks

Stefan Koch

summary: - evdev is not compatible to QT-applications
+ evdev is not compatible to QT-applications when using tablets
bugbot (bugbot) on 2011-02-19
tags: added: kubuntu
YAFU (yafu) wrote :

@Alexei, This bug is not related to that bug.
The problem is related with this bug in Qt:

There is a simple workaroun that solves the problem by modifying the "src/gui/kernel/qapplication_x11.cpp" file in qt-everywhere-opensource-src-4.8.1.tar.gz source. I think the package in Kubuntu is "libqtcore4" (qt4-x11):
In the Krita forum, in page 1 and 2 they discuss the workaround.
This bug causes that if you use a non-Wacom graphics tablet, the stylus pressure sensitivity not working in Qt programs (Krita, pencil).
Would be nice if could be include that workaroun in Kubuntu 12.10 - Quantal Quetzal

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in xserver-xorg-input-evdev (Ubuntu):
status: New → Confirmed
Jonathan Riddell (jr) on 2012-09-24
affects: xserver-xorg-input-evdev (Ubuntu) → qt4-x11 (Ubuntu)
Jonathan Riddell (jr) wrote :

This is best fixed upstream as we don't have the knowledge or hardware to test it

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