Clutter Project

Hi all;

it’s been a while, I’ll admit.

Clutter has been in deep maintenance mode since 2016, when 1.26 was released. I formalised this in 2019, when I updated the README, mostly because people are still filing bugs related to GNOME Shell in the Clutter and Cogl issue trackers.

Starting from GNOME 42, Clutter and its related libraries:

• Cogl
• Clutter-GTK
• Clutter-GStreamer
  
  have been removed from the GNOME SDK run time. This means it is finally time to officially archive Clutter & friends.

What does this mean

Clutter, Cogl, Clutter-GTK, and Clutter-GStreamer will be moved to the Archive group in GitLab once GNOME 42 is released in March. You won’t be able to file new issues, or open new merge requests. No new releases will be made.

If you’re writing GNOME Shell extensions, then nothing changes for you: GNOME Shell has had internal copies of Cogl and Clutter for years.

If you are maintaining a GTK3 application using Clutter, Clutter-GTK, and Clutter-GStreamer, I strongly recommend you move to libadwaita, GTK4 and to GStreamer. In the meantime, you should add Cogl, Clutter, and every other dependency to your Flatpak manifest once you update the dependency on the GNOME run time.

Parting words

Clutter was created 17 years ago, in 2005. At the time, the Linux landscape was dramatically different than what we have today: integrated GPUs were severely underpowered, and discrete GPUs were basically unsupported on Linux. Embedded platforms only had very low powered GPUs, with closed source binary blobs. To put this in context, Clutter arrived just before the iPhone was first unveiled, and GNOME 2 was half-way through its life. Thanks to Clutter we were able to experiment with hardware accelerated rendering of UIs and with animation frameworks; we were able to create a complex, extensible compositing window manager in the form of GNOME Shell. Many of the ideas that were first iterated inside Cogl and Clutter, like a retained tree of render commands, are now being used inside GTK itself.

17 years of Clutter development live on in GTK, libadwaita, GNOME Shell and any other Mutter-based compositor. If you contributed to Clutter, you have my deepest thanks; if you used Clutter, I hope you were happy with the results.

It’s been a fun, rewarding ride; I’m proud of what we’ve achieved, and curious to see what we’re going to see next.

As always, have fun.

One of the core tenets of the Clutter API design since the 1.0 days, six years ago, is to use delegation whenever possible. We have ClutterLayoutManager for layout management; ClutterContent for content display; ClutterAction for event handling; and ClutterEffect for content post-processing.

Up until now, the Clutter API, lacked a way to delegate mapping an actor state to a separate state object — something like a “model/view” split. Sure, we had ClutterModel to store some state in a tabular form rows of data organized in columns of attributes, but there was no way to represent that data, and, more importantly, the data itself was decomposed into separate values, with little to no effective or efficient way of grouping it into proper objects, unless you shoved object instances into the model.

The history of ClutterModel is also one fraught with expedient. The reason it was introduced in Clutter 0.6 was because of the lack of a corresponding data structure in GLib itself; the only similar data structure could only be found in GTK+ — i.e. GtkTreeModel. Given how tied GtkTreeModel is tied to GtkTreeView, we simply could not provide a view actor or interface inside Clutter, at the time. We did add simple view actors in layers above Clutter, like Tidy or Mx, but they were tailored to specific use cases and thus unsuitable to be reintegrated back into the low level API.

Since the 0.x days, there have been many changes in the GNOME core platform. One of those changes is GListModel, available starting from GLib 2.44. The list model API is fairly simple, and geared towards collections of GObject instances, which can then signal changes through property notification. You can see this in effect in the GtkListBox API.

For all these reason, I’ve added two new methods to the actor class, available starting with the 1.24 stable cycle, that allow you to bind a GListModel to a ClutterActor, and create children that represent objects inside the model:

• clutter_actor_bind_model() — this function lets you control the whole child creation phase through a simple delegate function; it’s the obvious port of the GtkListBox method linked above
• clutter_actor_bind_model_with_properties() — this is a convenience function that takes over the child actor creation, and lets you specify the type of the children to create, as well as the properties to bind, in a simple way

Clutter ships an example of this new functionality; while it may seem overly verbose, it shows how to neatly encapsulate model, view, and controller into three separate classes, and let the Clutter and GObject API take control of the relationship between the types. This should help you when modelling your UI and your logic code, and improve the maintainability of your application.

Back when I started hacking on Clutter, the Python bindings were the first thing I wrote. In order to make them happen, I had to understand the intent of the library, in order to fix the API to be binding-friendly. It was another time — a time before introspection made run-time bindings that automatically acquired support for new API once the underlying shared library changed. I had to learn the CPython API; the code generation utilities that turned C header files into defs files and defs files into C code; and, finally, the build system used by PyGTK that blended all this stuff on one end, and spat out a Python C module on the other.

For a long while, the Python bindings for Clutter have been based on that particular brand on insanity; people were able to switch to the introspection-based ones and drop PyClutter entirely, but the API was not as nice to use, and you’d be missing out on some niceties provided by both Python and Clutter.

In 2011, Bastian Winkler started porting the whole infrastructure to the overrides mechanism provided by PyGObject; instead of just loading the Clutter introspection data, you’d load a pure Python module that wrapped specific bits of the exposed API, and made it nicer to use.

For various reasons — mostly lack of time on my side — that work was bit-rotting in a branch of the Git repository. Well, no more. The master branch of the PyClutter repository is now providing introspection overrides similar to the ones for GTK+. I also added a bunch of examples, ported from their C equivalent, to show the idiomatic use of Clutter in a Python context.

I’ll probably do a release, but I’d be happy if somebody wanted to pick up the bindings and run with them — I’m not much of a Python programmer myself.

I sent this announcement to the mailing list as well.

for the past couple of years, Clutter has been developed off of a topic branch, while the master branch has been reserved to the development of the API-incompatible 2.0 series.

since the 2.0 series will likely not happen, and given the confusion that the layout of the repository induced in new contributors, I decided to do some surgery on the Git repository.

starting now, Clutter will follow the classic model of “development happens in master, stable releases happen from topic branches”.

the clutter-1.22 branch, which was being used for the development of Clutter 1.22 and meant to be used for GNOME 3.16, has been merged into the master branch.

the clutter-1.22 branch will be left alone, until Clutter 1.22 is released, at which point it all changes between now and the 1.22 branch point will be merged back into the clutter-1.22 branch, like it used to happen.

given that all the changes on the master branch were either commits in preparation for 2.0, or cherry picks from clutter-1.* branches, I opted to just revert them all; they are still recorded in the history, so it’s trivial to cherry pick them out. the merge itself retains all the history of the existing topic branches.

since I only used reverts and merges, there aren’t any forced pulls. the integrity of the Git repository is left intact.

I’m going to change jhbuild and gnome-continuous to pull from master for the current development cycle, as soon as I’ve thoroughly tested the change. if you are using jhbuild to build Clutter, you won’t notice any change, but you should double check that the branch you are using is the correct one, if you have a habit of building Clutter manually.

have fun!

• moving day! the new mailing list for the Clutter project is now hosted on http://t.co/QnGTRxeL: https://t.co/m4nRpy8V #
• if you were subscribed on http://t.co/4cFfFv91 you should already be subscribed to the new list #
• stay tuned for more moving news! #
• in other news: work for Clutter 2.0 has started in earnest; the wip/clutter-1.99 branch landed on http://t.co/IiKOkFD6 last night #
• diffstat against master: 295 files changed, 5669 insertions(+), 45500 deletions(-) #

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hi everyone;

a couple of years ago we started moving infrastructure away from a server hosted at the Intel OTC. Git and Bugzilla were the first two services moved under the GNOME infrastructure ((or to GitHub for non-GNOME specific components)); the Wiki followed a month ago.

today, we move the mailing list from lists.clutter-project.org to mail.gnome.org and the blog to blogs.gnome.org.

I would like to thank the Intel IT team for taking care of the Intel/OTC side of things, and the GNOME System administration team for their help in the migration — kudos.

there are still some bits missing — the cookbook, for instance, still needs a new home on developer.gnome.org; and the clutter-project.org domain needs to be transferred — but I’m sure we’ll be able to sort these issues out soon.

in the mean time, have fun with Clutter!

Good news, everyone!

A new Clutter release is now available at download.gnome.org/sources/clutter/1.12/.

Release Notes

• This version is API and ABI compatible with the current stable release of Clutter.
• Installing the contents of this release will overwrite the files from the installation of the current release of Clutter.
• Bugs should be reported on the Clutter Bugzilla product.

List of changes since Clutter 1.10

For detailed announcements see:

• 1.11.2
• 1.11.4
• 1.11.6
• 1.11.8
• 1.11.10
• 1.11.12
• 1.11.14
• 1.11.16

Add ClutterScrollActor

ClutterScrollActor is an actor that provides a scrollable viewport to show a portion of its children.

Add ClutterTransitionGroup and ClutterKeyframeTransition

Two ClutterTransition subclasses that provide grouping and keyframe-based transitions to the explicit animation API of ClutterActor.

Add new transformation API to ClutterActor

ClutterActor now provides a ‘pivot point’ that is used for all transformations: scaling, rotation, translation; also, any actor can be transformed by providing a 3D matrix, bypassing the decomposed transformations; finally, any actor can apply an initial transformation to its children. All matrix-based properties are also animatable.

Add multi-touch gesture recognizers

ClutterPanAction, ClutterZoomAction, and ClutterRotateAction are gesture recognizers that can be used to detect common multi-touch gestures. The ClutterGestureAction class has been modified to make it easy to create new gesture recognizers.

Layout manager improvements

ClutterGridLayout is a new layout managed implementing a flexible grid; setting the allocation of an actor will respect the actor’s easing state, making animatable layout managers easy to write; any actor can automatically expand in both the horizontal and vertical directions, and the expansion will bubble up to its parent.

Deprecations

ClutterCairoTexture (replaced by ClutterCanvas); ClutterTexture (replaced by ClutterImage); ClutterMedia (replaced by clutter-gst API); ClutterAnimation, ClutterAnimator, ClutterState (replaced by the implicit and explicit actor animation API); ClutterLayoutManager’s animation API (replaced by the implicitly animatable ClutterActor:allocation property); ClutterActor’s paint and pick signals have been deprecated.

List of changes since Clutter 1.11.16

Fix the device tracking for core X11 pointers

If a master input device can emit both touch and pointer events we end up in an inconsistent state; we should account for this case when tracking the stage that contains the events of each input device.

Respect text direction in BinLayout

The text direction of the children of an actor using the BinLayout layout manager should be taken into account, both when using the Actor’s align flags and when using the legacy BinAlignment flags.

Translations updates

Hindi, Telugu, Catalan, Malayalam, Japanese, Bulgarian, Kannada.

List of bugs fixed since Clutter 1.11.16

• #684214 – messageTray: Fix summary position in RTL locales
• #684552 – Track coordinates and device ids in test-events
• #684530 – Print device number in debug messages from input-device
• #684509 – Mouse events lost after touch event from virtual core pointer

Many thanks to all the contributors to the Clutter 1.11 development cycle

Bastian Winkler, Emanuele Aina, Jasper St. Pierre, Lionel Landwerlin, Chun-wei Fan, Daniel Mustieles, Fran Diéguez, Piotr Drąg, Neil Roberts, Tomeu Vizoso, Alejandro Piñeiro, Chao-Hsiung Liao, Nilamdyuti Goswami, Alexander Larsson, Ihar Hrachyshka, Tom Tryfonidis, Tristan Van Berkom, Мирослав Николић, Bastien Nocera, Christian Kirbach, Cosimo Cecchi, Yuri Myasoedov, Alexander Shopov, Alexandre Franke, Andika Triwidada, Aurimas Černius, Carles Ferrando, Daniel Korostil, Debarshi Ray, Dirgita, Duarte Loreto, Evan Nemerson, Jonh Wendell, Matej Urbančič, Rob Bradford, Robert Bragg, Sasi Bhushan Boddepalli, Andre Kuehne, Andy Wingo, Ani Peter, Ask H. Larsen, Bruce Cowan, Bruno Brouard, Chandan Kumar, Daniel Nylander, Danielle Madeley, Dimitris Spingos, Dominique Bureau, Enrico Nicoletto, Frédéric Péters, Gil Forcada, Giovanni Campagna, Jordi Serratosa, Kenneth Nielsen, Kjartan Maraas, Krishnababu Krothapalli, Martin Srebotnjak, Matthias Clasen, Mike Ruprecht, Nishio Futoshi, Owen W. Taylor, Peter Hutterer, Rajesh Ranjan, Rico Tzschichholz, Rudolfs Mazurs, Rui Matos, Shankar Prasad, Sjoerd Simons, Stefano Facchini, Viktor Nyberg.

Have fun with Clutter!