The Maliit buildbot

After having set up the typical things open source projects needs like a website/wiki, mailing-list and bug-tracker, Maliit now also has something not so common: a build-bot.

As Maliit consists of several components that can be built in several different ways (and for several different platforms), we wanted to automate the build and tests of the different variations to ensure that we do not break any of them. This is especially important for variations which are not easy to test for the individual developers, like for instance Maliit on Qt 5.

The software chosen to help with this task was Buildbot. Getting an initial instance it up and running was very quick and pain-free, especially thanks to packages being easily available and the excellent documentation. The current setup now builds, tests and installs the two major components we have: Maliit Framework and Maliit (Reference) Plugins, in the most important build/config variations we have. A total of 12 individual build jobs, plus 2 meta-builds. The configuration for the instance can be found in the maliit-buildbot-configuration repository.

For security reasons the build-bot is not directly exposed to the Internet. Instead a script runs every 5 minutes to generate a static HTML website and publish on the public web-server: Maliit build-bot

Buildbot says: All green!

This gives us a minimal continuous integration system for Maliit, which for now will hopefully helps us avoid breakage. In the future, the usage of the build-bot might extend to include:

  • Automating the release process
  • Testing of merge-requests/patches before merging to master
  • Automated integration/system testing, complementing the unit-tests
  • Triggering external builders for packaging. OpenSUSE OBS, Maemo 5 Garage, etc.
  • Automating certain aspects of bug-lifetime. Resolving when fix is committed, closing on release if pre-verified, etc


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GTK+ application support integrated into Maliit mainline

GTK+ application support for Maliit input methods has existed for a long time, but up until now it has lived in separate repositories. This has been inconvenient for users and for developers, and was the major cause for it to not be on the same level as the Qt support. This has changed as the GTK+ support has now been merged into the maliit-framework repository, and along side the Qt support. Maliit 0.80.8, which was released yesterday, contains these changes.

Maliit running on WeTab with Fedora 15, showing QML reference plugin and GTK+ application

Two implementations existed for Maliit GTK+ support. One was written by Javis Pedro as part of a Google Summer of Code project for MeeGo in 2010. His blog has several posts on the topic. The other implementation was maintained by Raymond Liu (Intel). This is the implementation shipped in Meego Netbook, and the one improved by Claudio Saavedra (Igalia) as part of the GTK+ on MeeGo project. It was also the only one that was updated to work with the DBus connection changes that was done quite some time ago, and supporting both GTK 2 and 3. For these reasons this was the implementation integrated into mainline Maliit.

Once the code was integrated, improvements soon followed. The application now correctly reconnects to server, and make install will automatically update the GTK+ input module cache on Ubuntu, thanks to Łukasz Zemczak (Canonical), and on Fedora. This means GTK+ application support will work out of the box, no twiddling needed.

While this is a huge step in the right direction, the GTK+ support is not as good as for Qt yet. Javis Pedros implementation has features that does not exist in mainline, so code/principles can hopefully be reused from there to implement these. This includes custom toolbars and attribute extensions, and content type hints for text entries. Other features looks hard to implement due to limitations/differences in the input context plugin architecture found in GTK+, and will probably need work in GTK+ itself to solve.

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Silent Stream Of Godless Elegy – Návaz

I have a strong preference for music in a language I can understand, if nothing else than for the opportunity to mumble along. But “Návaz”, the latest album from Czech band Silent Stream Of Godless Elegy, is a little gem, even if I can’t understand a word of the Czech lyrics.
Návaz, like the previous albums is a doom metal album with strong influences from Moravian folk music and lore. What I like most about this album are the heavy contrasts: Quick, playful violins against slow, drudging guitar riffs; soft female voice against harsh male voices; traditional folk instruments and musical themes against modern metal.

Here is the opening track, Mokoš, which I think is quite representative:


Those who don’t have the stomach for the above, thinking it is too noisy, might still enjoy the songs Sudice or Samodiva. More samples are available on their Myspace page. You can find the album at Amazon.

If you liked this music you should also consider checking out In Via (2010) by Illuminandi. Style wise it leans closer to gothic metal, more gloomy and bleak, but overall very much the same type of feel.


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Combining PySide and PyGObject introspection bindings

Some while back I added basic GObject Introspection support to GEGL and GEGL-GTK master a while back. This will* allow application developers to write their Gegl + Gtk based applications in any language supported by GObject Introspection, like Python, Vala and Javascript. For GeglQt, the Qt integration library for using Gegl in Qt based applications, it was natural to use PySide to provide Python bindings for it. The initial setup was quick and easy, thanks to the binding tutorial, but there was one challenge.

The current widgets provided by GeglQt are for displaying the output of a node in the GEGL graph. Therefore they have methods with the following signature to hook up it up:

From gegl-qt/nodeviewwidget.h
GeglNode *inputNode() const;
void setInputNode(GeglNode *node);

GeglNode is a GObject (from the C based glib) subclass, and without help the bindings generator (Shiboken) does not know what to do with it so the method cannot be bound. PySide could have been used to also generate bindings for Gegl itself, but what we actually want to do is to make use of the existing PyGObject based bindings.

Marcelo Lira on #pyside let me know that this should be possible by adding some annotations to the typesystem.xml file, and implementing a Shiboken::Converter<T>. It is indeed possible, and for the above type looks something like this:

From typesystem_gegl-qt.xml
<primitive-type name="GeglNodePtr">
      <conversion-rule file="geglnode_conversions.h"/>
      <include file-name="pygobject.h" location="global"/>

From geglnode_conversions.h
namespace Shiboken {
struct Converter<GeglNodePtr>
    static inline bool checkType(PyObject* pyObj)
        return GEGL_IS_NODE(((PyGObject *)pyObj)->obj);

    static inline bool isConvertible(PyObject* pyObj)
        return GEGL_IS_NODE(((PyGObject *)pyObj)->obj);

    static inline PyObject* toPython(void* cppObj)
        return pygobject_new(G_OBJECT((cppObj)));

    static inline PyObject* toPython(const GeglNodePtr geglNode)
        return pygobject_new(G_OBJECT(geglNode));

    static inline GeglNodePtr toCpp(PyObject* pyObj)
        return GEGL_NODE(((PyGObject *)pyObj)->obj);

The PyGObject C API and the GObject type system is here being used to implement what Shiboken needs. The attentive reader will note that GeglNodePtr is used and not GeglNode*. This is a simple “typedef GeglNode * GeglNodePtr“, which looks to be neccesary with current PySide (1.0.6) to avoid it being confused by the pointer. Hopefully that is fixable and won’t be necessary in the future.

With this solved, I committed the initial Python support to GeglQt master yesterday. It contains a trivial Python example showing the usage. Some build cleanups, binding generator tweaks and testing remains to be done, but expect Python support to be a prominent feature for GeglQt 0.1.0


* There are still a lot of GObject Introspection annotations missing in Gegl. See the tracking bug. Help wanted!

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Making GEGL easier to use in graphical applications

So, in the last couple of months I’ve been working a bit on GEGL. Some of the work has already been covered by LWN, so I guess it is time that I blog about it…

GEGL is a generic image processing library which is used by applications like GIMP, (and in the future maybe MyPaint and DarkTable). It provides applications with a graph based image processing backend that can do non-destructive processing of high-bitdepth images, among other things.

One of the problems that I think has been limiting adaptation of GEGL has been the entry barrier to starting to use it in a graphical application. While GEGL provides the image processing backend, it did not provide good and easy ways of displaying the output on screen. Now it does!

GTK+, Clutter and Qt integration libraries

Some code for integrating GEGL in GTK+ based applications has existed in the GEGL tree for a long time, but it was not well maintained and there was no public API. After brushing up the code to use Cairo for rendering and to support both GTK+ 2 and 3, it was split out to a separate library and repository: gegl-gtk. This library now provides a GtkWidget for displaying the output of a node in the GEGL graph, with basic support for scaling and translations. Any change in the GEGL graph will be reflected in the view widget. This makes it trivial for applications using a GTK+ based user interface to get started using GEGL, see for instance the provided examples in C or in Python.

The same functionality is provided for Clutter based user interfaces by gegl-clutter in form of a ClutterActor. This code was previously available as clutter-gegl, but has now been renamed and moved to be a part of the GEGL project, and is maintained by Øyvind Kolsås. Example code in C.

Last but not least, gegl-qt was created to serve the needs of applications using Qt based user interfaces. The different widget systems (QWidget-, QGraphicsWidget- and QML-based) are all supported. In addition to the features currently available in the GTK+ and Clutter versions, the Qt view widgets also support auto-scaling and auto-centering. Python bindings via PySide is planned, but blocking on a PySide issue at the moment.

A pretty boring screenshot showing two QWidget based examples (code: 1, 2) for transformations:

Artwork: “Wanted“, speedpainting by David Revoy

The first stable release of gegl-qt and gegl-gtk will hopefully be available soon. The list of tasks can be found in the README files.

Display operations

In GEGL, image processing is described as a graph of operations. “gegl:display” and “gegl:gtk-display” operations existed in the gegl tree, and by attaching one of these to a node in the graph one could display the output of the graph at the given node in a window . Such display operations are useful for applications that just want to show the output of a graph without having to use a GUI library directly.

The problem was that both of these operations were optional, so applications could not rely on this functionality to be present. This is solved by letting the “gegl:display” operation be a meta-operation, which uses other operations as a handler to actually display the output. Such display handler operations are now provided by gegl (optional, using SDL), gegl-gtk (using GTK+) and gegl-qt (using Qt). In addition a fallback operation that will export a PNG file and launch an external application to display it will be provided in GEGL.

More to GEGL stuff to come soon, hopefully.

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Lost in Thought – Opus Arise

If you’re a fan of traditional progressive metal, you might want to check out Lost in Thoughts debut album: Opus Arise.

Released April 29th this year, Opus Arise features some very solid songwriting much in the style of Dream Theater and similar bands. The musicianship is generally excellent, and the production is stellar. On the downside, this is not a very original album by any measure, you will not find too many fresh ideas or expressions in this album. So if you’re looking for something that takes progressive metal in a new direction; look elsewhere.

Here is the opening track, Beyond the Flames.

My favorite tracks include the slower Blood Red Diamond and the kicking closing track Assimulate, Destroy. You can find the album on Amazon.

Sadly the band had a car accident on their first European tour in late May, which left the drummer with a broken leg and having to undergo surgery. A news post comment from the drummer, and a recent interview seems to indicate that the recovery so far is going OK. Hopefully he will be fully recovered, back to playing drums, soon.

A friend told me that I should blog about music again. This was a shot at doing just that.

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Workshop & BoF schedule at Desktop Summit 2011 published

We in the the organizing team have now published the schedule for pre-registered Workshop & BoF sessions at the Desktop Summit 2011 in Berlin.

There is still time to register for ad-hoc sessions, and we will have two dedicated “hacker rooms” where you can sit down with like-minded people and work on what you like!

See the webpage for more information.


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Registration open for Workshops & BoFs at the DesktopSummit 2011

As a member of the local organizing team for the Desktop Summit 2011 in Berlin, I’m glad to say that you can now register your workshop or BoF session. These sessions take place during the last 3 days of the conference, and complement the presentations that take place during the 3 first days: The Workshops & BoFs sessions are hands-on sessions where people get together to discuss and work on issues face to face.

Short excerpt from the news entry on the webpage:

All forms of hands-on activities that aim to further the Free Desktop are welcomed. Examples of such sessions include BoF, project and cross-project meetings, workshops, hacking sessions and training/teaching sessions. Each session is self-organized and it is up to the hosts and participants to decide if the session is to be loosely oriented around a set of topics, or have a well-defined agenda.

The organisation committee would like to schedule as many of these sessions beforehand as possible. We expect over 1000 visitors and scheduling helps to ensure minimal overlap with other sessions and allows us to provide a clear timetable for the visitors.
The remainder of the rooms will be scheduled via the wiki but we urge you to pre-register and get a proposal in before the deadline, July 3rd!

I will be proposing a session or two of my own very soon, I suggest you do the same! Use this link

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MyPaint and OpenRaster talks

One of my goals for this year was to give a presentation at a conference. And I can now say that I have achieved that goal.

I gave a talk about MyPaint at Libre Graphics Meeting 2011 in Montreal, Canada: MyPaint – the past, the present and the future.

[hdplay id=1]

Download in Ogg/Theora

I will also be giving a lighting talk at the DesktopSummit in Berlin about OpenRaster. It looks like this will be on August 7th at 14.00, but you should of course come for the whole week. Just look at the awesome program!


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Example plugins for Maliit available

In Maliit input methods are implemented as plugins. This flexibility is important because it allows the same framework to provide very different text input methods, without us having to implement them all. Different virtual keyboards, hardware keyboard input, handwriting, speech-to-text, input methods for accessibility, et.c. are all possible with the Maliit framework. This makes the input method plugin API the most important extension point.

To make it simple to start developing an input method for Maliit, we have written a set of example plugins that can be used as a skeleton* for a new input method. There is one “Hello World” example showing the C++ interface, and one showing the newly added QML interface. The latest documentation for the framework in HTML format is also included, along with a simple test application. How to get started is documented on our wiki page: Go!

A very conventional example: An input method that allows you to input "Hello World"

A nice thing is that these examples are in our framework repository: built as part of the standard build, with simple tests run as part of our test-suite. This ensures that the examples stay up-to-date and working, something I find that step-by-step, code-and-talk tutorials in some documentation repository/directory typically do not.

If you want to look at real-life examples of plugins, check out the Meego Keyboard code (C++), the Meego Keyboard Quick code (QML), or foolegg from’s cute-input-method code (QML with Pinjyin support!). Also make sure to check out Michael Hasselmanns talk at the Meego Spring 2011 Conference: Developing custom input methods for Meego.

If you hit any issues, contact us through one of our communication channels.

* Note that currently the license of the examples is LGPLv2 like the rest of the framework.

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