(adding awt-dev)
Let me add a few comments.
already Wayland is the default on RHEL 8, OL 8, Ubuntu 21.04 and I am
sure others too.
It is the default, but not in every case. Wayland may be turned off
deliberately if you are using a Nvidia graphics card, so you need to
take extra steps to get it working
<https://askubuntu.com/questions/1334825/what-are-the-steps-to-run-wayland-on-21-04-with-optimus-nvidia>.
I faced this issue on Ubuntu 21.04.
However things getting better
<https://www.phoronix.com/scan.php?page=news_item&px=NVIDIA-470-Wayland-Friendly>with
Nvidia 470 drivers, its beta released
<https://www.nvidia.com/download/driverResults.aspx/176525/en-us> on
2021.6.22. So probably it won't be a problem in the near future.
Consequently we expect quite shortly to propose an OpenJDK project
that will consider the goals of
- a short to medium term solution for JDK running on Wayland in X11
compatibility mode
- a medium to long term solution for JDK running as a native Wayland
client.
Both goals having a common task: we will need to implement
java.awt.Robot functionality for Wayland(at least).
So it makes sense to make XToolkit's java.awt.Robot work under Wayland
first, and then reuse this code for native Wayland client.
I see two major tasks here: taking screenshots and mouse/keyboard
control. As far as I know there is no standard way to implement they
across all display servers yet.
Possible ways to implement this:
* taking screenshot:
o open issue against Wayland, may be resolved
someday:https://gitlab.freedesktop.org/wayland/wayland/-/issues/32
<https://gitlab.freedesktop.org/wayland/wayland/-/issues/32>
o
https://flatpak.github.io/xdg-desktop-portal/portal-docs.html#gdbus-org.freedesktop.portal.Screenshot
<https://flatpak.github.io/xdg-desktop-portal/portal-docs.html#gdbus-org.freedesktop.portal.Screenshot>
o via DBUS interface(display server dependent),
e.g.https://github.com/flameshot-org/flameshot/blob/master/src/utils/screengrabber.cpp#L43
<https://github.com/flameshot-org/flameshot/blob/master/src/utils/screengrabber.cpp#L43>
* generating key/mouse events:
o
https://flatpak.github.io/xdg-desktop-portal/portal-docs.html#gdbus-org.freedesktop.impl.portal.RemoteDesktop
<https://flatpak.github.io/xdg-desktop-portal/portal-docs.html#gdbus-org.freedesktop.impl.portal.RemoteDesktop>
o generating new virtual input device, uinput, superuser
privileges required, looks too flaky
https://unix.stackexchange.com/questions/422698/how-to-set-absolute-mouse-cursor-position-in-wayland-without-using-mouse
<https://unix.stackexchange.com/questions/422698/how-to-set-absolute-mouse-cursor-position-in-wayland-without-using-mouse>
This still need more investigation, butxdg-desktop-portal
<https://github.com/flatpak/xdg-desktop-portal>looks more preferable way
for now.
Please see below some caveats for OpenJDK native Wayland client:
You can't control a position for a top-level window.
<https://gitlab.freedesktop.org/wayland/wayland/-/issues/183>
This will also affect a splashscreen windows. It is still possible to
control position under XWayland though.
Looks like we will just accept it.
Top-level window decorations.
Initially Wayland had only client-side decorations(you have to draw it
by yourself).
As of now server-side decorations are available by XDG-Decoration
protocol <https://gitlab.gnome.org/GNOME/mutter/-/issues/217>.
However server-side window decorations are not mandatory and not all
compositors are supporting it, e.g. Mutter(Gnome Shell's compositor).
Gnome Shell is the default on Ubuntu, so we will need to provide window
decorations somehow. One of possible solutions is to use Gtk to create a
window for us.
--
Thanks,
Alexander.
On 7/7/21 6:24 AM, Philip Race wrote:
For a number of years the Linux community has been working on a
complete replacement for the 1980's era X11 desktop display server
protocol
with new protocols and libraries that support client-side rendering
and a compositing desktop windowing system.
This work is being done under the auspices of the Wayland project [1]
and there is a reference
implementation of a Wayland compositor called "Weston".
A new client written for the Wayland desktop has no dependency at all
on X11, but Wayland also provides a compatibility
mode where the X.org X11 server runs along side Wayland, so that
thousands of X11 applications can continue to run.
Presently all distros that ship the Wayland server, also still ship
the pure X11 server and the user can select
which one to use on the login screen. However there will come a time
when Wayland is the only choice and
already Wayland is the default on RHEL 8, OL 8, Ubuntu 21.04 and I am
sure others too.
At that time Java for Linux will "mostly" run via the X11
compatibility layer, but would not pass the JCK,
since some important APIs, notably those of the java.awt.Robot class
[2] will fail with Wayland.
We need to solve this so that pure Java and applications which mix
Java and X11 APis can work.
But even then this would mean Java on Linux is not a first class
desktop citizen, which is not desirable for
the long term, given the importance of Linux to many Java developers
as well as to active
individual and corporate contributors to the JDK project.
Indeed there have already been informal discussions for some time with
various parties that have expressed
interest in helping towards the outcome of supporting Wayland
Consequently we expect quite shortly to propose an OpenJDK project
that will consider the goals of
- a short to medium term solution for JDK running on Wayland in X11
compatibility mode
- a medium to long term solution for JDK running as a native Wayland
client.
There are some unknowns and questions, such as what are the options
for supporting Robot ?
What other support is missing ? What platform APIs should the
implementation use ?
How does a native Wayland solution interoperate with OpenJFX ?
Comments, expressions of interest etc are welcome.
-Phil Race, for the Java client groups.
[1] : https://wayland.freedesktop.org/
[2] :
https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/Robot.html
