#220 Wacom pen input lags

[paolo muratore-ginanneschi]

xournal compiling on macosX 10.15.7 works only after passing
make CFLAGS='-g -O2 -std=gnu89 -Wno-implicit-function-declaration'
(macports workaround)
Libraries etc. from homebrew latest.
Xournal opens correctly. Pen input (handwriting) via wacom tablet lags, almost non usable.
No similar on xouranlpp. I would be grateful for suggestions on how to fix. I miss my xournal!
Thank a lot for your time.

[Denis Auroux]

Sorry I am not familiar with how xournal ports behave on macOS (I don't have a mac). If you previously had an older version working fine on a mac with the same tablet -- is this a new problem with the latest version of macOS / libraries / ... ?

How much lag is there? (roughly -- half a second? 2-3 seconds? stroke only shows up after you lift the pen?) Does it matter if you draw short strokes (say a dotted line) or long ones? (a long curve that loops a lot) ? Does drawing fast vs drawing slow change the lag?
(Trying to figure out if it's a bottleneck with event processing speed, or a constant delay.)

Also: does the lag happen only with the pen or also when drawing with a mouse/touchpad/...? is the lag still there if you disable Options -> Use XInput ?

Finally, do you have any software running that might interfere with pen input? (eg Windows with some fairly common settings tries to perform gesture detection first rather than immediately passing pen input to xournal, I don't know if the macOS wacom driver might try to install something like that).

Denis

[paolo muratore-ginanneschi]

Hi Denis,
thanks for your swift reply, I really apprecite it :) !

I believe the problem emerged after a library upgrade. I use homebrew to install open source (it works like apt-get in debian/ubuntu linux). In the past I never had the need to pass CFLAGS to the compiler to install, standard instructions worked.
I say I believe because recently I had to reinstall macosx from scratch. Before reinstallation xournal worked without issues.

The lag is about half a second. Not noticeable if I draw a line but makes very hard to write. The lag occurs the same way with pen and mouse. The problem is clearly with xournal as it does not appear in xournalpp.

I tried disabling XInput but with no avail. I would exclude other software interference. I suspect some library problem but I do not know where to start from.
Thanks again!

[Denis Auroux]

Thanks for the details -- very helpful even though I must admit that I'm
completely at a loss about what to do, or which library to consider most
suspect in this. One question might be whether other GTK2 applications
have the same problem (the main one these days is GIMP if you get the
stable versions 2.10.x) are similarly affected. (Xournalpp uses GTK3
which can talk to macOS via different means).

One possibility is that it's not even a library but rather an X server /
X11 compatibility layer issue. My understanding is that MacOS no longer
includes XQuartz by default -- did you reinstall it or another X11
server, or is xournal being run without an actual X server on your new
system? If so this might explain the input issues -- on Linux, Xournal
has been doing worse on Xwayland (X11 emulation over a new display
engine) than on plain X11, though support is becoming better.

(I don't think the CFLAGS issue indicates anything worrisome, it's just
that the compiler settings in some of the latest development
environments are a bit aggressive and intolerant of rusty old code like
xournal's unless prodded with appropriate compiler flags -- which I
should probably add to the xournal distribution once I figure out which
ones are necessary on what sort of system without breaking compatibility
with other environments).

Denis

[paolo muratore-ginanneschi]

Hi again,

I installed XQuartz. No improvement in xounal but xournalpp on its turn stopped working (no input possible). I then removed XQuartz, xournalpp back to normal, xournal still lagging.
I tried to install xournal via macports but x11 conflicts prevented it start. I did not have time to inquire that any further. I suppose your intuition is correct.

Concerning CFLAGS the macport ticket which helped me is
https://trac.macports.org/ticket/61147

Thanks again