Howdy,
As you probably know, surfaces created by plasmashell need to be treated
specially by the compositor. For example, notification windows must be
always on top, panels may go above and below normal windows. That's why
we use a proprietary protocol called plasma-shell for creating shell
surfaces that provide the functionality required by plasmashell.
Unfortunately, there are technical issues with the plasma-shell protocol
that can be fixed only by rewriting the protocol from scratch. Luckily
for us, the sway community came up with a protocol called layer-shell
that a desktop environment could use in order to build components such
as panels, notifications, etc. The layer-shell protocol doesn't suffer
from the problems that we have with the plasma-shell protocol.
The cool thing about is that with the layer-shell protocol it will be
possible to make applications such as latte-dock run across desktop
environments.
Over the last a couple of weeks, I've been working on a layer-shell
protocol implementation in kwin. With the compositor side being almost
complete (it's still under code review), it's a good time to focus on
the client side.
The biggest difference between the layer-shell protocol and the
plasma-shell protocol is that positioning is done in relative terms in
the former protocol. For example, instead of saying "please place me at
the specified position (x, y)," a client must say "please place me 10px
away from the left screen edge." Which brings us to the first problem:
we need to ditch specifying absolute window coordinates and transition
to relative positioning. Unfortunately, we cannot do it all at once, so
we need some way to smoothly transition between the two approaches. I
see several options:
* Mimic absolute positioning via relative positioning. It's good as a
short-term solution, but imho, we need something better
* Introduce a Plasma::Dialog with relative positioning and start
gradually porting all plasma components to it
The second problem is that we need to integrate the layer-shell protocol
in Qt in some way. Since plasmashell creates both normal windows and
special-purpose windows, we need to use **both** the xdg-shell and the
layer-shell protocol. It's not really clear how it can be achieved.
The most ideal case is where Qt provides native support for the
layer-shell protocol out of the box. API-wise, plasmashell needs to set
the layer, the namespace, the margins, etc. Alternatively, we could fork
QtWayland QPA and extend it with features we need. Either way, we need
some changes in Qt in order to be able to use several shell surface
protocols simultaneously.
Any ideas or thoughts on what the best way to integrate the layer-shell
protocol in plasma and Qt is?
Cheers,
Vlad
- Integration of layer-shell in plasma Vlad Zahorodnii
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