Pressure sensitivity not working on Mac

[ThoFrank]

In Mac OS pressure sensitivity of my wacom bamboo tablet is not working.
I dug around in the code and found that pressure is read in
src/gui/inputdevices/InputSequence.cpp: getInputDataRelativeToCurrentPage() : line 474
The value of pos.pressure however does not change. Currently unsure on how to tackle this.

In Gimp it is working correctly.

[andreasb242]

There is a GTK Example. May you can install it over macports or what you are using.

If not, compile it yoursel:

gcc pkg-config --cflags gtk+-3.0 exampleinput.c -o exampleinput pkg-config --libs gtk+-3.0

exampleinput.c.zip

Gimp is using GTK2, we are using GTK3.

Currently macOS is not official supported by Xournal++, because no developer has currently time for this.
So if you have time, help is welcome, even if it's only to debug the input handling ;-)

[ThoFrank]

Thanks!
So here is what I found out:
gtk is currently not supporting advanced tablet features ( see issue ). Demo only shows pointer location and only default device.

For myPaint there was a huge workaround using x11 and a few patches.
I will try to look into gimp's code to find their workaround. Maybe it could be used for Xournal++, too.

[andreasb242]

The issue you mentioned is not very old:

Opened 2 months ago by

May we should check if we get a patch for GTK instead of trying to do it in Xournal++.
This example (which is not the right four us, for sure) is looking really simple.
https://developer-docs.wacom.com/display/DevDocs/macOS+X+Sample+Code+Downloads

[andreasb242]

On this bug is a patch attached!
https://bugzilla.gnome.org/show_bug.cgi?id=695701

It's not that much.
https://bug695701.bugzilla-attachments.gnome.org/attachment.cgi?id=241615

They migrate the Bugzilla to gitlab, because of this I put this patch also here as attachment:
0001-Quartz-Tablet-pressure-support-draft-2.patch.zip

But I won't do macOS development at the moment, I'm a Linux user and at the moment I'm already working on the Windows Port ;-)

[andreasb242]

I wrote to the GTK Mailing list for a contact person. It don't look like a big problem.

[andreasb242]

GTK Bug https://gitlab.gnome.org/GNOME/gtk/issues/1551

[andreasb242]

I got it working. The patch is not yet ready, but it's coming soon.

[andreasb242]

GTK Pull Request, still not merged, because I get a lot of review issues.
https://gitlab.gnome.org/GNOME/gtk/merge_requests/541

[andreasb242]

This is fixed with the release 1.0.8, even not yet merged into official GTK Repo.

[cecilyen]

Any update about supporting pressure sensitivity in Mac?

By the way, I found libmypaint could support pressure sensitivity brushstrokes on multiple platforms. https://github.com/mypaint/libmypaint