Thoughts 'n Stuff

Travel plans for September

Planning my travels for September made me yearn for a travel assistant — it’s impressive how much time one can waste with crappy booking websites and clueless hotel staff. On the other hand, doing it myself allowed me to shuffle things around until I was happy with the plan. Not sure my imagined travel assistant would have had that much patience ;–)

Anyway, tomorrow I’ll be attending the 2nd Automotive Linux Summit (Sep 19-20) and the schedule is packed with interesting talks. Sadly, there won’t be any time for me to visit Warwick Castle again, which is just 15 minutes away from the venue. They say it’s for kids, but the Warwick Castle daily shows are well worth a visit, even for grown-up kids.

The Automotive Linux Summit clashes with the X Developer Conference (Sep 19-21) in Nuremberg, which means I can only attend XDC on Friday (and perhaps the beer hike on Saturday). Now, I haven’t suddenly become a X hacker over night, but I want to know how the progress in Wayland is perceived and whether there’s some good advice for our Wayland input method work. It would have been a great opportunity for me to learn more about EGL and new trends in OpenGL, but I’ll have to leave that to my colleague Jan Arne Petersen, who will attend the whole conference.

After staying in Nuremberg for the weekend, I will spend a few days in Munich (not for the Wiesn) before I head home to Berlin.

Thanks to Openismus for sending me to ALS and XDC!

Designing an input method system for Wayland

As mentioned before, Jon and I met with Kristian Høgsberg and Peter Hutterer during FOSDEM 2012. The discussion quickly revolved around Wayland and input methods. Kristian and I basically picked up from where we left after the Qt Contributor Summit last year in Berlin.

Right now, there is no explicit input method support in Wayland, and it’s the responsibility of the applications to provide such. But we came to the conclusion that moving it into Wayland provides several benefits.

That is why I spent some time during February to write down an initial design proposal, using the two years of experience from working in the application framework team for the Nokia N9. It has gotten longer than expected, but hopefully it is structured well enough to still be accessible.

From the introduction:

Currently, Wayland has no explicit text input method support and relies entirely on toolkit-specific or platform-specific solutions. This is awkward for platforms that support multiple toolkits. The resulting fragmentation and re-implementation would make it hard to attract developers of high-quality text input methods. These developers would generally prefer a unified architecture that lets them ignore application-specific or platform-specific details. This would let them simultaneously target all platforms that support Wayland.

We believe this goal can be reached by adding two new Wayland protocols, of which only one requires adaptation by toolkit providers.

The idea is not new, XIM has been around since the dawn of time. Because of the protocol’s daunting complexity, it apparently never became popular among application toolkit providers. That is why I decided to split up the envisioned Wayland input method protocol up into two:

• The Wayland text protocol, to be used between the Wayland compositor and its clients. It tries to keep input method knowledge to a minimum and therefore can be used for any kind of (hardware) input that results in text input.
• The Wayland input method protocol, to be used between the Wayland compositor and the input method system, which can either run as a stand-alone process or inside the compositor process.

In the proposal, I explain my ideal solution where applications and input method system are completely separated from each other and where the compositor acts as a mediator between them. I continue with alternative solutions that are feasible but have several drawbacks. Towards the end, there is a comparison matrix that features all discussed solutions.

There is an important aspect though: The alternative solutions provide an iterative implementation approach to reach the ideal solution. The obvious idea here is that already in early stages, we get testable prototypes. The solutions with a compositor-hosted input method system for instance allow others to think about window management policies that take input methods into account, whereas I could continue my iterations towards the ideal solution.

Anyhow, the next steps are now to discuss the proposal in a wider public (feedback from developers of exotic input methods especially welcome!), possibly also at upcoming conferences, and to come up with a prototype implementation so that we can iron out protocol bugs.

I would probably target Qt 5 as the first application toolkit to support the Wayland text protocol, followed by GTK+ and perhaps Enlightment. One also needs to take the popular desktop shells into account, such as Gnome Shell, Unity and Plasma Active.

Maliit could fill the role of a reference input method system, but we should have at least one more implementation, at some stage (IBus comes to mind, naturally).

Looks as if this could keep me busy for the better part of 2012, but it would be great if we could get at least the Wayland text protocol into Wayland 1.0. It’ll require some luck though.

Input methods and Wayland in Qt5

I was attending the Qt Contributors' Summit 2011. During the key note, it was promised that everything is up for discussion so I took my chance to discuss about improving input methods support for Qt5.

After some initial discussions with Kristian Høgsberg (Wayland, of course) and Jørgen Lind (who works on Qt Lighhouse), I also addressed Wayland. It became clear that one needs some kind of input method interface directly in Wayland. Kristian immediately started with a small prototype, in order to explain better how a Wayland compositor can provide a much better window management policy than what we currently have with Maliit and X11.

I think the session itself was really successful. I was surprised at the strong interest in this topic.

It became apparent that we should do something about Qt's input context API. For instance, add more input methods hints, come up with a better interface that describes the focus widget, preedit handling, orientation support and so on.

Now we only need to agree on how to make it happen :-)