Tag Archives: kwin

KWin and tiling

Personally I haven’t ever been a big user of tiling windowmanagers such as i3, awesome and what not, is not much the workflow style I want 24/7 out of my desktop, but there is definitely something something to say about that kind of multitasking when it makes sense, when is important to see the status of multiple windows at once for some particular task.

Plasma’s KWin has since a long time a basic support for tiles via the quick tiling support, by either dragging a window at edges or corners, or via keyboard shortcuts. This feature is very good, but very basic, and while there are 3rd party tiling extensions such as Bismuth which is a very nice thing, but window geometry managing outside the core always can bring you only so far.

Over the last month I have been working to expand a bit the basic tiling capabilities, both the quick tiling with the current behavior and a more advanced UI and mechanism which lets the user to have a custom tiling layout. Here it is a very short screencast about it.

tiling manager effect

Tiling is done by a full screen editor done as a fullscreen effect where is possible to add /remove/resize tiles. When moving a window if the Shift modifier is pressed, the window will be dropped in the nearest tile. Resizing the tile in the editor will resize all the windows connected, and on the converse, resizing tiled windows will resize the tiles as well. (also the traditional split screen quick tile will gain this feature, so if you have 2 windows tiled to get half of the screen each, resizing one will resize both)

Another use case we thought about for this tiling feature is to address people which have those fancy new ultra wide monitors.

Random stock photo from the interwebs of an ultra wide screen

There are very few applications which have an UI that actually make sense maximized on such proportions (i could imagine perhaps KDEnlive, Krita and very few other productivity apps). Most applications just look wrong, but with custom tiling areas, those can become sub “maximization” zones.

It is not intended to be a full fledged replacement for I3 or Bismuth, but rather an hopefully robust mechanism in the core with a pretty minimal and unobtrusive default ui, then the mechanism will have scripting bindings which should allow for 3rd party extensions to use it and implement interesting variations of the tiling WM out of it.

For now the feature is quite basic, a notable thing missing which i still hope to get in time for 5.27 is having separate tiling layouts per virtual desktop and activity (for now they’re per-phisical screen), but hopefully the full thing should land on a Plasma 5.27 release near you.

Tooltip handling

An informational tooltip in Plasma is an item that shows extra informations for items such as task items, and is a single entity, moving along what you want to know more of, rather than magically appear out of nowhere (that’s the kind of “magic” the human brain doesn’t like).
A problem with Plasma tooltips was that they tried to animate themselves, that is usually not a good idea on X11, due to its old async architecture.
But KWin to the rescue! if we want a smooth animation of both the position and the size of the tooltip, the compositor is the place where to do it.
With its scripting user interface, it was even possible to implement it completely in JavaScript.
You can see it in this video taskbar tooltips animating and resizing/morphing in a similar way Windows 7 does.

Btw, the animations in he video looks way less smooth than are in reality, due how terrible screencasting is under X11, but for that:

Wayland will fix it!

There is a Blur in my Wayland

Over the last few days I decided to help Martin a bit with the ongoing effort on Wayland, since there are still many parts of work missing in order to have a full Plasma Wayland session to just work, but it’s impressive how fast it’s getting there.
It was just a tiny part but is worth sharing it as it brings pretty pictures! (and shows how easy is to contribute).
The popups of the plasma shell need custom positioning code as normal applications can’t position themselves anymore for security reasons, plus KWin uses its effects framework to do a couple of things on plasma panels and popups:

Shadows: the shadows are rendered by KWin, they aren’t really a part of the window, as the shadow must not count anything in the position and resizing phase, but just a visual effect on it, it’s also more semantically correct.
Background effects: both the panel and the popups have a blurred background plus a contrast/saturation effect, to make it more readable and prettier.

After hooking a protocol to control such effects into wayland, here’s the result, almost undistinguishable (there is still a pretty visible graphical issue, points for finding it) from your current X11 Plasma 5.4 session:

So, what needed to be done?

KWayland protocols: each KWin effect that can now be controlled with X properties need its own wayland protocol extension in order to achieve the same thing, I wrote one for blur behind and background contrast (shadow was already there). The good news here is that Martin is working on a tool to auto generate the binding code from the XML specification of the protocol.
KWayland-integration repo: The effects that had KWndowSystem API to control them, need a Wayland implementation as well, this goes in the KWindowSystem wayland plugin contained in the kwayland-integration.git repo.
Modify the KWin effect: then the kwin effect needs to read the data that the client wrote on the surface with the new kwayland protocol and control the effect, in a way that is behaviorally identical to the X11 way, that came from reading X properties from the window

As an “user” of the infrastructure, I’m very impressed about the work that went in the Wayland port of KWin and from the KWayland framework: it really makes using a very challenging and “peculiar” plain C API very easy and elegant in a way familiar with our cozy C++/Qt world.
I can say that is a learning curve soft enough for everyone to jump in and help the big scary transition if they feel to.