On 03/10/2022 08:25, Alexandros Frantzis wrote:
On Sun, Oct 02, 2022 at 09:13:27AM +0100, Terry Barnaby wrote:
Hi,
I am developing software for an instrument embedded system using NXP CPU's
and the Wayland/Weston GUI system.
The hardware platform has a main LCD panel and an optional plug-in HDMI
monitor. The GUI is currently running with the Weston kiosk-shell and a
single application is shown full screen on the LCD. Weston is configured so
that the HDMI monitor appears to the right of the LCD screen and if the
desktop-shell is used applications can be dragged across.
Now what I would like is for the application to be moved to the HDMI
monitor/screen when the monitor is plugged in (resizing as needed).
With X11 I would have simply, from the application, moved its top level
window coordinates and without a window manager or with a simple window
manager the window would move to the area of the second screen.
Now I understand that Weston and the standard Wayland protocol's do not even
allow a window move request to be made.
So I assume I might have to implement a whole new Weston shell, perhaps
based on the kiosk-shell, and either invent some form of protocol to allow
the application to request the shell to move it or get the shell to see HDMI
plug in events and move the application and tell it to resize.
I don't have much knowledge of Wayland/Weston internals (lots of X11), so
can anyone give me any pointers on how I might achieve this in the
simplest/quickest way ?
Terry
Hi Terry,
Assuming you only care about the fullscreen case, an application can
request (but not force) a fullscreen placement for a toplevel surface
with:
xdg_toplevel_set_fullscreen(xdg_toplevel, wl_output)
In your application you could listen for advertised wl_output globals
and issue a set_fullscreen request for the preferred wl_output (e.g.,
based on the wl_output/xdg_output name). Since you are only dealing with
a specific compositor under your control, you can be fairly confident
that you will get consistent behavior here, i.e., the compositor will
honor your request.
Note that kiosk-shell provides a mechanism in the .ini file to declare
the placement of applications on specific outputs. However, the output
placement decision is static, made only when the surface is first
created/committed to, not for any subsequent output reconfigurations.
Making this output placement in kiosk-shell work more dynamically
(optionally), with the shell moving the surface to the preferred output,
could possibly be a useful enhancement for some use cases.
HTH,
Alexandros
Many thanks for the reply and info.
I will have a go with xdg_toplevel_set_fullscreen() and maybe have a
look at creating a special shell to do this as well. Actually I have got
this working to a degree in a copy of the kiosk-shell adding code to the
kiosk_shell_handle_output_created() and
kiosk_shell_surface_notify_output_destroy() to move the views. But I
can't get the shell to clear its background when I move the application
window, indeed it doesn't seem like the kiosk-shell code is actually
setting the background at all as looking at the code it should set it to
grey but it is black on my system using Weston 9.0.0. I will investigate
further.
Terry
