java-gnome 4.1.3, released 4 May 2013
Overview, News
Tutorials, API, and Hacking
Binaries and Source
Mailing Lists, IRC, and Reporting Bugs


java-gnome 4.1.3 (4 May 2013)

Adventures in Tooltips .

A third release in the 4.1 series, with improved coverage of GTK’s tooltips and styling functionality. Also includes numerous build fixes and maintenance of the build infrastructure.

Thanks to Guillaume Mazoyer and Sarah Leibbrand for their contributions!


java-gnome 4.1.2 (30 Aug 2012)

Applications don’t stand idly by.

After a bit of a break, we’re back with a second release in the 4.1 series covering GNOME 3 and its libraries.

Application for Unique

The significant change in this release is the introduction of GtkApplication, the new mechanism providing for unique instances of applications. This replaces the use of libunique for this purpose, which GNOME has deprecated and asked us to remove.

Thanks to Guillaume Mazoyer for having done the grunt work figuring out how the underlying GApplication mechanism worked.

Idle time

The new Application coverage doesn’t work with java-gnome’s multi-thread safety because GTK itself is not going to be thread safe anymore. This is a huge step backward, but has been coming for a while, and despite our intense disappointment about it all, java-gnome will now be like every other GUI toolkit out there: not thread safe.

If you’re working from another thread and need to update your GTK widgets, you must do so from within the main loop. To get there, you add an idle handler which will get a callback from the main thread at some future point. We’ve exposed that as Glib.idleAdd(); you put your call back in an instance of the Handler interface.

As with signal handlers, you have to be careful to get back from your callback as soon as possible; you’re blocking the main loop while that code is running.

Miscellaneous improvements

Other than this, we’ve accumulated a number of fixes and improvements over the past months. Improvements to radio buttons, coverage of GtkSwitch, fixes to Assistant, preliminary treatment of StyleContext, and improvements to SourceView, FileChooser, and more. Compliments to Guillaume Mazoyer, Georgios Migdos, and Alexander Boström for their contributions.

java-gnome builds correctly when using Java 7. The minimum supported version of the runtime is Java 6. This release depends on GTK 3.4.


java-gnome 4.1.1 (11 Jul 2011)

To bump or not to bump; that is the question

This is the first release in the 4.1 series. This introduces coverage of the GNOME 3 series of libraries, notably GTK 3. There was a fairly significant API change from GTK 2.x to 3.x, and we’ve done our best to accommodate it.

Drawing with Cairo, which you were already doing

The biggest change has to do with drawing; if you have a custom widget (ie, a DrawingArea) then you have to put your Cairo drawing code in a handler for the Widget.Draw signal rather than what used to be Widget.ExposeEvent. Since java-gnome has ever only exposed drawing via Cairo, this change will be transparent to most developers using the library.

Other significant changes include colours: instead of the former Color class there’s now RGBA; you use this in calls in the override...() family instead of modify...() family; for example see Widget’s overrideColor().

Orientation is allowed now

Widgets that had abstract base classes and then concrete horizontal and vertical subclasses can now all be instantiated directly with an Orientable parameter. The most notable example is Box’s <init>() (the idea is to replace VBox and HBox, which upstream is going to do away with). Others are Paned, various Range subclasses such as Scrollbar. Separator, Toolbar, and ProgressBar now implement Orientable as well.

There’s actually a new layout Container, however. Replacing Box and Table is Grid. Grid is optimized for GTK’s new height-for-width geometry management and should be used in preference to other Containers.

The ComboBox API was rearranged somewhat. The text-only type is now ComboBoxText; the former ComboBoxEntry is gone and replaced by a ComboBox property. This is somewhat counter-intuitive since the behaviour of the Widget is so dramatically different when in this mode (ie, it looks like a ComboBoxEntry; funny, that).

Other improvements

It’s been some months since our last release, and although most of the work has focused on refactoring to present GTK 3, there have been numerous other improvements. Cairo in particular has seen some refinement in the area of Pattern and Filter handling thanks to Will Temperley, and coverage of additional TextView and TextTag properties, notably relating to paragraph spacing and padding.

Thanks to Kenneth Prugh, Serkan Kaba, and Guillaume Mazoyer for their help porting java-gnome to GNOME 3.


java-gnome 4.0.20 (11 Jul 2011)

This will be the last release in the 4.0 series. It is meant only as an aide to porting over the API bump between 4.0 and 4.1; if your code builds against 4.0.20 without reference to any deprecated classes or methods then you can be fairly certain it will build against 4.1.1; if we’ve missed something please let us know.


Website update

We’ve reorganized the java-gnome website. API Documentation is now found at doc/api/4.1/. This prepares us for the upcoming API bump.


java-gnome 4.0.19 (14 Feb 2011)

What do you mean that’s not the font I asked for?

This release includes some minor feature enhancements.

Preliminary coverage of Pango’s Font object. Font is Pango’s abstraction describing a typeface, and is what is actually loaded. We’ve exposed the methods that allow you to find out what was actually loaded for a given FontDescription request. You do this with Context’s loadFont() and then Font’s describe(). Thanks to Behdad Esfahbod for explaining how all this works.

Exposed a few utility functions, including one to find out if your program is running in a terminal or from the Desktop directly.

GTK improvements

Further improved some corner cases involved in using Actions, and now you can make them with named Icons.

There are some odd corner cases, especially with TextView, where idle handlers need to run before you have the calculations you need ready to query. One workaround appears to be letting the main loop cycle, so we’ve exposed Gtk.mainIterationDo() and the Gtk.eventsPending() which wraps it.

Build improvements

Building java-gnome on Mandriva now works! Thanks to Liam Quin for helping QA the top level configure script.


java-gnome 4.0.18 (23 Dec 2010)

My compressed original is better than your uncompressed copy

This is a bug fix release. A serious crasher was occurring when you requested a the underlying [org.gnome.gdk] Window backing a Widget, as is often necessary before popping up context menus. Thanks to Kenneth Prugh and Guillaume Mazoyer for their help in duplicating and isolating the problem.

Better image rendering

While we’re at it, we’ve merged work in progress offering coverage of the librsvg Scalable Vector Graphics loader. This allows you to draw an SVG image as a vector graphic to Cairo (which itself works in vector form, of course), and is a substantial improvement over just loading the .svg with gdk-pixbuf (which rasterizes the graphic to a bitmap first, of course). Load the image with Handle, then draw it with Context’s showHandle().

We’ve also added coverage of Cairo Surface’s new setMimeType(), which allows you to embed the the original [ie JPEG, or to a lesser extent PNG] image in PDF output rather than just the decoded, rasterized, and very huge bitmap image that Cairo uses on screen and would otherwise have used in PDF and SVG output. So 100 kB JPEGs stay JPEGs instead of turning into 12 MB bitmaps. Yeay.

java-gnome now depends on Cairo 1.10 and librsvg 2.32.


java-gnome 4.0.17 (18 Nov 2010)

All dictionaries are equal. But some dictionaries are more equal than others.

After some 6 months of development, this release includes substantial improvements across the library. Thanks to Guillaume Mazoyer, Michael Culbertson, Douglas Goulart, Vreixo Formoso, Mauro Galli, Thijs Leibbrand, and Andrew Cowie for their contributions to the library, and also to Yaakov Selkowitz, and Alexander Boström for their updates to the build system.

Enchant Dictionaries

Improve the utility of the Enchant library by exposing functionality to test wither a dictionary exists for a given “language tag”, and to list all available dictionaries. Add speciality functions to the Internationalization class facilitating the translation of language and country names so you can present the list of available languages properly translated in the user’s language.

GTK improvements

Introduce Icon as a strongly typed class to wrap “named icons” available in an icon theme, complementing the previous coverage of “stock icons” provided by the Stock class. Add methods to DataColumn, TreeModel, Image, and Entry making these available.

Also in TreeView land, Vreixo Foromso contributed a change to make DataColumnReference generic, noting that this was his “one great irritation” with java-gnome. Itch scratched, apparently. :)

A fair bit of work went into polishing coverage in various classes. We now have coverage for Adjustment’s various properties (necessary if you want to drive a scroll bar around yourself without using one built into a ScrolledWindow).

We’ve also introduced a new signal in the Assistant. You can now define the behaviour of an Assistant using the ForwardPage signal with the setForwardPageCallback() method. It can help you to skip pages when you need to. When going back, the Assistant will also skip the previously skipped page.

java-gnome now supports GTK+ 2.20 and introduces the new Spinner widget that can be used to display an unknown progress.

Added coverage for another utility function, this time the one that escapes text in strings so that it can be safely included when Pango markup is being used.

If you need to ensure whatever has been copied to the clipboard is available after your application terminates, you can call Clipboard’s store().

Thread safety

Fixed a fairly serious bug in the interaction between the memory management code and the thread safety mechanism. Amazing we got away with this one so long, really. Thanks to Vreixo Formoso for helping with analysis of the crash dumps, confirming the diagnosis, and double checking the proposed solution. The problem only showed up if you were making extensive use of something like TextViews which (internal to GTK) did its drawing in a background idle handler.

Also fixed a crasher that turned up if your cursor theme didn’t have a certain named cursor. ENOTGNOME, but anyway.

More drawing

The Cairo graphics library continues to be a joy to use and we continue to make minor improvements to our coverage as people use it more. In particular, based on help from Benjamin Otte and others we’ve refined the way you create a Context in a Widget.ExposeEvent, improving efficiency and taking advantage of some of the underlying support functions more effectively.

Looking ahead

With GTK 3.0 coming closer to reality, we’re keeping close track of the activity there. GTK 3.0 is a pretty vast API and ABI break from 2.x with some fairly major changes to the way Widget sizing works, along with an overhaul of the drawing system. We’ll be updating java-gnome to meet these changes in the months to come.


java-gnome 4.0.16 (17 Jun 2010)

Accelerating is good for you


java-gnome now has full support for accelerators, the key bindings (such as Ctrl+Q for “quit”) typically used to activate MenuItems and Actions. The heart of the API is in the AcceleratorGroup class, although you actually use it care of MenuItem’s setAccelerator() and Action’s setAccelerator(). Huge thanks are due to Thijs Leibbrand for having navigating the almost incomprehensible native API and figured out how we could best add coverage for Java programs.

Cairo Operations

Though we’ve had support for Cairo’s various “operators” (different modes for combining what’s being drawn with what’s already on the surface) for some time, we didn’t really know what we were doing. Thanks to the careful work of Kenneth Prugh, we’ve now got full coverage in the Operator class along with a magnificent series of illustrations. These are the same pictures as are in the underlying Cairo documentation, but like our screenshots, ours are generated automatically by java-gnome programs whenever you build the documentation.

Miscellaneous improvements

The style CENTER has been added in ButtonBoxStyle.

Coverage of GTK’s new InfoBar Widget was added by Guillaume Mazoyer, who also made numerous touch ups to various core classes. The Activatable and Editable interfaces got some love. And methods to get “human readable” byte sizes have been added to the Glib utility class.

Finally, we exposed the code needed to force GDK to revert to the pre GTK 2.18 behaviour of using native X Windows for every Widget. This shouldn’t be necessary — the whole point of major changes like the “client-side windows” branch are is that they are supposed to Just Work (and more to the point Just Work better, over time) — but it does give a workaround for unusual corner cases where either GTK, java-gnome, or the developer is constrained and needs some help.


java-gnome 4.0.15 (16 Mar 2010)

Radio things

This has mostly been a bug fix cycle with numerous internal quality improvements being made. A few developer visible API additions have been made, summarized below.

Unified radio handling

There are a number of controls in GTK that exhibit the “radio” behaviour of being in a group of which only one can be selected: RadioButton, RadioMenuItem, RadioToolButton and RadioAction. We originally had a class called RadioButtonGroup which was used when constructing RadioButtons to indicate which group they were a member of. In introducing overage of the other radio types, Guillaume Mazoyer implemented a generic grouping class called RadioGroup which is now used for all the radio types.

XDG utility functions

A number of utility functions (aka static methods) were added to Glib allowing you to access the various user and systems directories as specified by the XDG specification. These are Glib.getUserConfigDir(), Glib.getUserDataDir() and friends.

Miscellaneous improvements

Better control of positioning when popping up context menus; you can specify co-ordinates when calling Menu’s popup().

The no-arg “convenience” packing methods we invented for HBox and VBox were causing more trouble than they were worth because people we not understanding the implications of the “default” packing values. So these are deprecated; the full four-argument packStart() and packEnd() have been present for a long time and are to be used in preference.

Serkan Kaba spent a bit of time working with the text version of the ComboBox API. Apparently no one had needed removeText() so he added that.

A number of improvements to the coverage of GDK’s event masks were merged. This is work originally by Vreixo Formoso necessary to support the Widget.MotionNotifyEvent signal, though it has use in other applications. Widget now has addEvents() and setEvents() to this end.

Finally, Guillaume needed to handle selections in IconViews. The API is similiar to that in TreeView, but doesn’t use the same TreeSelection helper class; the methods are directly on IconView. Boo for asymmetry. Anyway, we’ve exposed isSelected() on both TreeSelection and IconView so you can find out if a given TreePath is currently selected.

Better initialization checking

Logic checking that the library has been properly initialized has been refactored, making it harder to accidentally misuse java-gnome when getting started [or when starting a new program after you’ve been using the library for years and forgotten the basics :)].

Last but not least, a number of bug fixes; one was developer-visible; Enchant.requestDictionary() now returns null like it claimed to if you request an unknown dictionary. Nice catch, Serkan.

All the source files have the full (ie traditional) GPL v2 header text now; the files comprising the library as used at run-time have GPL headers text + the Classpath Exception text. Needed to be done. Makes for a large diff this release, but makes the Ohloh’s page for java-gnome happy too :).


java-gnome 4.0.14 (16 Dec 2009)

You have to compose in order to enchant

Access to Enchant spell checking API

Coverage of the Enchant spell checking facade (which was already an implicit dependency arising from our GtkSpell coverage) is now included in java-gnome. It’s a lovely library with a simple to use API which in turn fronts for various back end spelling providers.

More detailed input handling

GTK’s handling of complex input methods is extraordinarily powerful, and of course present by default in the Entry and TextView text entry Widgets. If you’re doing your own text based work, however, you might need to capture the results of an input method being used to compose characters or words. InputMethod.Commit is where the result of a compose sequence is captured and delivered to the application.

We’ve also made numerous improvements down in GDK where events are processed; as a Java library we represent many naked low-level native entities with strongly-typed classes, and have improved our coverage here, notably with new Cursor constants representing the common use cases of changing the pointer.

Improved text rendering

Other minor improvements are present across the text rendering stack, notably with the ability to introspect where a Pango Layout has made its line breaks when wrapping via LayoutLine’s getStartIndex() and getLength() methods.

Guillaume Mazoyer finished up a work by Serkan Kaba resulting in us having coverage of the special LinkButton subclass of Button which can be used to present clickable URLs.

You can now create custom PaperSize objects, which is handy if you need to use Cairo to output PDF documents with a non-standard paper format.

Other changes

You can now use gdk-pixbuf to query an image on disk for its dimensions via Pixbuf getFileInfo() function calls.

There were of course miscellaneous improvements to various long established core classes, mostly fixing typos.

We now have the methods necessary to have ImageMenuItems actually show images (there’s a GNOME bug whereby suddenly icons are not showing in menus. So you need to either explicitly tell an ImageMenuItem that it should always show its image, or use the global Settings to say that Menus and Buttons should always have their icons showing).

The internal initialization sequence has been tweaked to ensure that GLib’s threads are initialized before anything else. This means java-gnome apps will work if glib 2.22.3 is installed; this is a workaround for bug 603774.

Headless testing

For a long time we’ve had to be careful in our test suite not to do anything that would cause a Window to appear or otherwise popup while the tests were running. But some for some test cases this is unavoidable, especially if the main loop needs to cycle. We now run the java-gnome test suite within a virtual X server (ie Xvfb), and as a result distros packaging the library can run the test suite on their headless build servers if they wish.

There’s a new base class for java-gnome TestCases needing to run in this environment.

Looking ahead

What’s ahead for java-gnome? That’s always a good question. At this point java-gnome provides a comprehensive API for development of user interfaces suitable for the GNOME desktop, and it’s incredibly rewarding to see people using the library for their own programs.

Development of java-gnome has continued pretty steadily, driven by people finding they need additional features from some of the underlying GNOME and FreeDesktop libraries we already expose. As a community we also work to fine-tune the performance and quality of the library through continuous improvement of the code base and its algorithms.

There are also people quietly working on experimental coverage of more unusual libraries such as GStreamer and Clutter which is pretty exciting to see.

People using java-gnome are always welcome to join us in #java-gnome to ask questions or just hang out! So happy hacking, and see you soon.


java-gnome 4.0.13 (27 Aug 2009)

Unicode. It’s bigger than you think.

This is a bug fix release to address a serious weakness in Java’s handling of Unicode characters.

Unicode handling

It turns out that Java’s chars are not pure Unicode codepoints. Most people know that Java String objects are arrays of Java chars, but in aggregate they are encoded in UTF-16 in order to deal with the fact that there are Unicode characters whose index is higher than 0xFFFF and which need more than two bytes to identify them. It’s a problem that an application developer has to deal with if they’re using high-range “supplementary” Unicode characters, but wasn’t something that would break java-gnome…

Except it turns out that the Java VM does not do UTF-8 translation properly. It has a hard wired limitation preventing it from writing out UTF-8 sequences longer than 3 bytes. Who knows what crack they were smoking when they decided that one. But things like TextView / TextBuffer work in characters, so we need characters. (actually, they work in UTF-8 bytes, but the offsets in our public API are the characters variants).

Luckily, we can get at the raw UTF-16 arrays backing Strings, and so in combination with GLib’s character set conversion functions, we’ve been able to redo our string handling internally so as to have correct treatment of Unicode codepoints. Lots of testing.

This surgery was almost entirely internal; Strings returned by java-gnome methods are of course still Java String objects. There was only one signature change in the public API: TextIter’s getChar() now returns Java int, not Java char.

New coverage

This release also features the work of Guillaume Mazoyer exposing some of the new features available in Entry Widgets, including displaying icons and showing progress bars in the background.

Along with minor enhancements to various miscellaneous classes.

With this release, java-gnome now requires GTK 2.16 or newer.


java-gnome 4.0.12 (24 Jul 2009)

Being Uniquely Notified while Spelling the Sources you are Viewing is good for the soul.

In addition to ongoing improvement in our coverage of the GTK widget toolkit, the next release of java-gnome begins to realize our vision to offer coverage of the broad suite of libraries making up the GNOME desktop.

New Coverage

The TextView text editing Widget has received two significant capability boosts. With the work of Stefan Schweizer, we now have coverage of the powerful GtkSourceView library with its impressive built-in multi [programming] language source highlighting features.

And with the contribution of GtkSpell coverage by Serkan Kaba, we can now offer spell checking in TextViews as well.

Two other GNOME libraries feature in this release. Serkan also contributed excellent coverage of LibNotify, enabling an application to create and send popups to be displayed by the desktop notification mechanism.

And, we expose LibUnique, which offers DBus-powered machinery enabling a developer to ensure only one instance of their application is running.

Continuing improvement

Lots of minor changes and enhancements throughout the core GTK libraries. Highlights include improved mouse button handling, filtering when choosing files, and further refinement to Pixbuf. Thanks to Peter Mossveld, Kenneth Prugh, Vreixo Formoso, Serkan Kaba.

Finally, thanks to Guillaume Mazoyer we now have coverage of EntryCompletion, the feature of Entry Widgets whereby available possible completions are offered to the based on characters the user has typed so far.

Looking ahead

There are a number of people working on various branches — some small feature extensions, and some major coverage additions that add signifant capabilies — but which haven’t quite made it to the point where they can be merged into java-gnome. We’ll see how these pieces of work fare in the coming months, but nevertheless the Java bindings for GNOME have reached a significant level of maturity and we are pleased to see people starting to use them in serious applications.


java-gnome 4.0.11 (1 May 2009)

This is a bug fix release.

We made a few mistakes in our handling of the PangoAttribute structures’ memory which resulted in VM crashes [unfortunately, the normal GNOME way of debugging things is to SIGSEGV. That’s fine for a C program but Bad™ for your average Java Virtual Machine as it takes out the entire process. We therefore work rather hard to avoid — or at least trap — this sort of thing]. Releasing corrections for these bugs was a priority.

Concurrently a significant internal improvement in our handling of accumulating Attributes into AttributeLists was made. While this is not user visible per se, we were able to drop the requirement that the text you were formatting already be in the Pango Layout before assigning the range that the Attribute would cover. You also no longer need to pass that Layout to setIndices(). This makes things a great deal easier if you are simultaneously aggregating the text and assigning markup.

Martin Garton contributed some documentation quality improvements and new coverage. Serkan Kaba made some minor fixes to ensure the unit tests run in a Turkish locale. And as ever there are small incremental improvements to various classes, including a number of additional properties exposed care of the work of new contributor Thijs Leibbrand.

Looking ahead

This was a brief cycle; as noted we’re mostly pushing some bug fixes. Meanwhile there are a number of significant branches underway by various hackers; which, hopefully, will feature prominently in the next release.


java-gnome 4.0.10 (5 Mar 2009)

Sculptures made of letters

This release is a landmark, because it features coverage of the Pango text rendering library and so, along with our coverage of Cairo, brings us to a complete solution for drawing graphics with text — be they custom Widgets, PDF documents, or beautiful vector illustrations.

In addition to merging Pango work from numerous contributors, we have made massive improvements to our Cairo coverage, support for writing PDFs, and better access to the system Clipboard.

Drawing API improvements

We’ve done a huge amount of refinement to our APIs for the ever fabulous Cairo Graphics drawing library, including full coverage of matrix translations, rotations, and scaling and more integrated ways of setting the source pattern to be used in stroke, paint, and fill operations. Thanks to Kenneth Prugh for having seen this through and having done the lion’s share of the testing.

The various use cases of setting a source pattern for a Context including RGB, RGBA, other Surfaces, already existing Pixbufs, etc have been combined into a series of setSource() method overloads.

We’ve also had a number of improvements in the lower levels of GTK relating to image rendering. The gdk-pixbuf library contains a capable image parser and we can now feed it directly from a Pixbuf constructor. Thanks to new contributor Martin Garton for his hard work getting that tested and accepted.

Drawing graphics often also requires drawing text. This release features coverage of Pango, GNOME’s powerful text rendering library. Pango is not just about drawing mere glyphs; it also includes a sophisticated paragraph layout engine which gives us a capable solution for drawing text onto Cairo Surfaces.

Thanks are due to Serkan Kaba and Kenneth Prugh have both been really helpful testing; it was Vreixo Formoso who did the original leg work in April that identified Layout as the key class that we needed to concentrate on and cleaned up much of the underlying infrastructure.

As we were working on this we had occasion to continue the polish in and around the TextView / TextBuffer APIs, including a number of convenience methods for inserting text while simultaneously applying multiple TextTags, and supporting changing default fonts.

We’ve also modelled “notify signals” for when a property changes; see the TextBuffer.NotifyCursorPosition signal for this in action.

Finally, thanks to contributions from Zak Fenton and Kamil Szymala we have support for applications running in composited window managers to have transparent backgrounds — which is an exceptionally cool effect, even if it doesn’t have much to do with creating HIG compliant usable applications :).

Handling cut & paste

The GTK clipboard APIs are fairly complex, in no small part because the underlying implementations in X are really rather complex. Our coverage here in java-gnome is still fairly basic relative to that, but it’s been enough for people working on applications like text editors to write text to the system clipboard, get notification when the clipboard changes, and read text back out again.

Printed document support

The work on Pango noted above represented the essential machinery necessary to make effective use of Cairo’s PDF backend, and this has started us down the road of covering the GNOME printing APIs. You can now generate .pdf documents with java-gnome, and we’ve included an fun example showing this in action.

Thanks to Nathan Strum for permission to use one of his sketches in the example (you might find reading the blog where we found this interesting — it’s a fascinating exposé of a graphic artist in action).

Continuing improvement

Thanks to new contributor Stefan Schweizer we now have better coverage of signals relating to Notebook style Containers, and to new contributors Miloud Bel and Bruno Dusausoy for numerous small improvements in and around ProgressBar.

Miscellaneous documentation improvements and minor feature improvements always feature in our releases, with minor changes having accrued in many classes.

Just as important as new coverage is getting rid of cruft that we don’t need. Libraries like GTK and GDK are, like any other mature project, full of deprecated, obsolete, and unnecessary code — not to mention things that we just plain don’t need in a Java binding of these underlying native libraries. We’re already pretty good about not generating translation Java or JNI C code for such things; this release continues our refinements in this area with a considerable refinement of the .jar and .so which is ultimately what we ship.

Finally, it’s worth noting that java-gnome’s test suite is now 40 unit test classes with 186 individual test fixtures. Combined with over 30 screenshot generating programs and 17 example programs, we actually have surprisingly good test coverage of our library. It’s high time they — and more to the point the people who work hard to create such tests — got as much credit as the visible public APIs do.

Anyone can run the tests (and anyone wanting to submit a patch had better run the tests!); they’ve been accumulating since java-gnome 4.0.0; it’s just:

$ make test


$ make doc

If you’re working in Eclipse launch class UnitTests as a JUnit test suite.

Build improvements

We have some fixes from new contributor Przemysław Grzegorczyk ensuring we include the correct headers in a few corner cases. This came to us via work on a GNOME Love bug, which is a first for us. Thanks!

Meanwhile, the ever industrious Serkan Kaba has added some changes to ensure that our magically locating the native shared library component of java-gnome works properly even under strange and unusual conditions.

Configuration and prerequisite detection on Open Solaris is improved thanks to reports from new contributor Kamil Szymala.

Instructions for how to optimally lay out your branches when working with java-gnome have been moved to the HACKING file. People intending to hack on the bindings from Eclipse are really urged to set things up this way as it will make their lives much easier. Also, using the latest release of Bazaar (ie bzr >= 1.12) is definitely recommended — it’s getting really fast. We’ve upgraded our public branches, so you will need 1.9 at a minimum.

Note to those creating packages for distributions: java-gnome now depends on the current stable GTK (ie gtk+ >= 2.14).

Looking ahead

Coverage of Poppler, GNOME’s PDF rendering library is well along, but didn’t quite make it in time for this release. It could very likely feature in the next version of java-gnome, as might coverage of GConf, GNOME’s simple store for application configuration options. People are also known to be working on coverage of GtkSourceView, libwnck, and librsvg. We’ll see what gets contributed!

The most exciting part about java-gnome at the moment, though, is the number of people working hard on applications using it. It takes a long time to write a mature, well rounded, robust end-user program, but there are some pretty cool projects ticking away out there, and it has been terrific to see the authors of these projects joining our community.

Happy developing,


Rendering text

One thing that was previously missing from our Cairo support was the ability to draw text. To that end we have been working on exposing the excellent Pango text rendering library. The ‘pango’ branch where the effort has been underway to polish coverage allowing developers add text when drawing has now been merged to ‘mainline’.

Pango is not just about drawing mere words. It also includes a sophisticated paragraph layout engine. This in turn represents the essential machinery necessary to make effective use of Cairo’s PDF backend; you can now generate .pdf documents with java-gnome, and we’ve included an fun example showing this in action.

Thanks are due to Serkan Kaba and Kenneth Prugh have both been really helpful testing; it was Vreixo Formoso who did the original leg work in April that identified Layout as the key class that we needed to concentrate on and cleaned up much of the underlying infrastructure.

The API documentation for Layout is pretty much the center piece of all this work. Improvements to various Cairo backends have also been underway; the descriptions at XlibSurface and PdfSurface may also be of interest.


java-gnome 4.0.9 (13 Oct 2008)

The pen is mightier than the sword

New coverage

This is the first release with coverage of GTK’s powerful TextView/TextBuffer multi-line text display and editing Widget. This has been the result of several months of careful effort to present a clean and self-consistent API while remaining faithful to the underlying implementation. This bulk of this work was done by Stefan Prelle and Andrew Cowie, with contributions from Kenneth Prugh and testing by many people in the #java-gnome community.

The snapshot at right is from ExampleInstantMessenger, included with the sources. It is a somewhat detailed example showing the use of TextView, TextBuffer, and related classes. Try running it!

Other improvements

Continuous improvement to various classes, especially in our documentation. Incremental changes have occurred in a number of places. In the TreeView/TreeModel APIs, some useful methods for translating TreeIters from one model to another have been added.

Also thanks to the persistent work of Stefan Prelle, we have nice coverage of GTK’s Assistant (aka druid, wizard, etc):

Better support for doing popup context menus, including some bug fixes. Thanks Srichand Pendyala for taking care of this and to Owen Taylor for having explained out some of the underlying implementation details.

And, as usual, incremental improvements to core classes, notably a few new signals here and there. Virtually every class has been touched in one way or another; most changes are cosmetic but they add up to significant contribution.

Reducing memory pressure

Internally, java-gnome maintains a lookup table so that pointers coming from the C side can be converted into proxy objects for the case where a proxy has already been created. In any library there a great number of transient and temporary objects and structures allocated, and we are no different. It turned out that registering these temporary objects was putting pressure on the lookup table. While these objects were properly weak referenced and being garbage collected (and thence freed), there were nevertheless an enormous number of temporary objects being inserted and removed from the lookup table — and that sort of thing causes hash tables to grow overly large.

To do something about this we have split the former hierarchy root into two classes. Only structures which have a persistent identity (which, in practise, means only GObjects and certain Cairo entities) are registered so they can be looked up by address later as necessary. These remain subclasses of the former root Proxy. The rest of the Java side proxies for are now subclasses of Pointer which is now the new root for our class hierarchy. These aren’t registered, essentially eliminating the transient pressure on the lookup table.

This is entirely an internal change. Users of released & packaged versions of the library will not notice any difference. Developers and hackers who have a checkout of the project source code may need to make clean if they haven’t since 'mainline' revno 567.

Thanks to Vreixo Formoso for doing the bulk of the leg-work on this one.

Making it easier to run java-gnome programs

Because java-gnome is directly binds to underlying system libraries, it has a native shared library component. This led to the usual development hassle of having to specify where this library is to be found if it were anywhere other than /usr and of course the nightmare of ensuring a VM used the right library in the event you were developing against or hacking on a newer version of java-gnome; in Java this meant:

$ java -classpath /opt/local/share/java/gtk-4.0.jar:. -Djava.library.path=/opt/local/lib com.example.Program

No longer!

The native shared library part of java-gnome is now located deterministically and loaded automatically. You don’t need to faff about with java.library.path on the command line or in your IDE any more!

$ java -classpath /opt/local/share/java/gtk-4.1.jar:. com.example.Program

Our native component is completely coupled to the specific release you are using, so sufficient version information is embedded in the .so name to ensure that the right library (and only the right library) is loaded.

There are no changes if you are simply working against an “in-place” development build of java-gnome, be it from command line, or in an IDE like Eclipse, things will Just Work™; again, no -Djava.library.path:

$ java -classpath ~/workspace/java-gnome/tmp/gtk-4.1.jar:. com.example.Program

Note to downstream packagers: running make install is now compulsory. This signals a build that it is no longer being used “in-place” but instead is to be prepared for installation to a system prefix (Gentoo got bit by this; hooray for downstream packagers testing release candidates!). If you need to change the install locations, you can specify overrides when you run ./configure, perhaps:

$ ./configure prefix=/usr jardir=/opt/share/java libdir=/usr/lib/jni

The defaults are all sensible, of course, and are as described in README.

Build system improvements

Serkan Kaba has contributed a number of internal improvements allowing the top level ./configure script to be precise about the versions of various GNOME dependencies we require.

With the release of GTK 2.14, various bits of the underlying libraries have been deprecated. Thanks to the hard work from Serkan Kaba and new contributor George McLachlan, java-gnome correctly builds against GTK 2.14 without any problems.

Note that java-gnome releases do not set GTK_DISABLE_DEPRECATED (this is a change from 4.0.8); thanks to Mart Raudsepp of the Gentoo Linux desktop team for pointing out why this would be better. These macros are still enabled for builds checked out from version control so hackers working on the bindings so will be able to keep up with ensuring we react to future deprecations (it’s always awesome when downstream is a part of the upstream community; Serkan and Kenneth are also Gentoo packagers, and take care of the java-gnome .ebuild for us).

Incidentally, the version constants identifying the library are now alongside the rest of the infrastructure. Public methods are now available if you want to use the API or release version number in a snapshot or example.

Looking ahead

We’re pretty happy with the state of the java-gnome right now. Coverage of the most important parts of GTK are in place. Our treatment of the underlying drawing library, Cairo, still has a bit to go, but the basics are there and a firm foundation to build from. More interesting are the remaining areas; the more general GNOME utility libraries and other parts of the Free Desktop stack that might be needed by an end-user application. It’ll be interesting to see how these areas evolve in the coming months.


Lorem ipsum

A major concentration of effort over the last few months has been to write appropriate public coverage to present GTK’s powerful but complex TextView/TextBuffer API, a Widget for presenting multi-line text and the backing store for manipulating it.

The ‘textview’ branch where this work has been taking place has finally been merged to ‘mainline’.

As this development cycle continues we will continue to review and refine the API we’re presenting, but this is nonetheless a significant milestone and one we’re justly proud of. Thanks to Stefan Prelle for having done much of the leg work and also to Kenneth Prugh for his support during testing.

You can read the API documentation for TextBuffer and TextView if you’re interested in how things are shaping up.


java-gnome 4.0.8 (15 Aug 2008)

Cleanups and fixups.

This release is mostly to push out bug fixes and internal improvements, setting the stage for some major new feature development. We’ve also taken the opportunity to introduce a major change to the way we connect handlers for signals.

New coverage and continuing improvement

With thanks to new contributors Stefan Prelle and Andreas Kuehntopf we have a number of small improvements to the TreeView/TreeModel APIs.

As always, Widget and Window saw a bunch of work, with Window.ConfigureEvent now being available and a number of additional property setters and methods relating to window type.

Widgets that scroll around a view of a broader underlying canvas have seen a fair bit of activity related to controlling that scrolling.

New features include refinements and new coverage of methods in a variety of lower level classes including that further support drawing operations. Bug fixes, debugging improvements, and defencive enhancements to our thread safety measures have also featured largely.

Signal naming change

We have changed the naming scheme used to name the interfaces that are used when hooking up signal handlers.

The names of the inner interfaces used to specify the prototypes of the methods which receive signal callbacks have changed to the pattern Button.Clicked, this being more appropriate to Java type naming conventions and providing better consistency between the signal name, the method to be implemented to receive the callback, and the method that can be used to emit this signal.

API compatibility to previous releases in the 4.0 series has been preserved. The old signal interfaces and connect() methods are @deprecated. Developers are encouraged to migrate quickly; new coverage will of course all follow the new pattern. Making the transition is is easy, especially in an IDE. Most of the people we’re aware of using the library have already ported their code. Just turn assertions on to double check.

Build changes

java-gnome now defines C compiler flags like GTK_DISABLE_DEPRECATED to ensure we are not linking against code that will be unavailable in GTK 3.0. Many thanks are due to new contributor Kenneth Prugh for having done some terrific grunt work to prune deprecated classes and methods from our .defs data so that java-gnome compiles without using these APIs.

The build system internally now ensures that multiple runs don’t occur simultaneously, fixing a number of annoyances that cropped up when using IDEs which tend to like trying to frequently re-run the build even if a previous one hasn’t finished.

Documentation, examples, and testing

Our API documentation and the growing set of example code have all been updated to reflect the new signal interface names. Doing so forced us to review a wide swath of the documentation, and so along the way a huge number of minor improvements were made. Given how detailed our JavaDoc is, this sort of painstaking work really makes a genuine contribution to overall quality.

There has been steady growth in our test suite, which is great. When combined with the snapshots used to illustrate our documentation, the coverage level is substantial.

Error handling continues to improve. In the (hand written) public API wrapper layer we do our best to catch misuses of the library before they get sent to the native code. But that’s not always possible, and in 4.0.7 we introduced a mechanism whereby GLib error messages get translated into Java Exceptions and thrown. As of 4.0.8, in addition to ERROR and CRITICAL, we also throw WARNINGs as Exceptions. Getting a stack trace this way has proved very useful in helping developers track down where they are making mistakes in using the library.


You can see the full changes accompanying a release by grabbing a copy of the sources and running:

$ bzr diff -r tag:v4.0.7..tag:v4.0.8

Because of the API changes to signal handling this release touches just about every public class in the library and so isn’t quite as clean (as a summary) as in previous releases — but it does show you everything that changed. :)

Looking ahead

Most of the contributors to java-gnome are working on branches that didn’t reach sufficient maturity to be merged in time for 4.0.8; that’s the way it goes sometimes. Major effort continues on implementing coverage of GTK’s powerful TextView/TextBuffer APIs, along with further drawing capabilities in Cairo and Pango. There have also been a surprising level of interest on other areas of the GNOME stack, with new contributors working on adding support to java-gnome for Nautilus, GStreamer, and even WebKit. Exciting stuff!


Signal API change

We have changed the naming scheme used to name the interfaces that are used when hooking up signal handlers.

Connecting a handler to a Button now looks as follows:

b.connect(new Button.Clicked() {
    public void onClicked(Button source) {
        // do stuff

Those developing with java-gnome will recognize that the inner interface’s name has changed to Button.Clicked, being more appropriate to Java type naming conventions and providing better consistency between the signal name, the method to be implemented, onClicked(), and the method that can be used to emit this signal, emitClicked().

The process which led to this change was discussed on the java-gnome-hackers mailing list; see first message if interested.

Interfaces with the old names and corresponding connect() methods are still present in the library (marked @deprecated, of course, and with assertions to encourage developers to migrate their code) so the upcoming release will preserve ABI compatibility.

The documentation posted here has been updated and a release candidate has been uploaded.


java-gnome 4.0.7 (30 Apr 2008)

Draw some.

In addition to improvements to our coverage of the GNOME libraries, this release introduces preliminary coverage of the Cairo Graphics drawing library, along with the infrastructure to make it work within a GTK program.

Drawing with Cairo


The trusty Cairo context, traditionally declared as a variable named cr in code, is mapped as class Context. Various Cairo types such as different surfaces and patterns are mapped as an abstract base class (Surface, Pattern) along with various concrete subclasses (ImageSurface, XlibSurface, and SolidPattern, RadialPattern, etc). Error checking is implicit: the library status is checked internally after each operation and an Exception thrown if there is a failure.

The gateway to custom Widgets is the EXPOSE_EVENT signal; this is where you can transition from the GDK Window to a Cairo Context and then begin drawing.

Thanks in particular to Carl Worth for having reviewed our API and having helped test our implementation.

New coverage and continuing improvement

The single option choice buttons in GTK are called RadioButtons and have now been exposed. When using them you need to indicate the other buttons they are sharing a mutually exclusive relationship with, and this is expressed by adding them to a RadioButtonGroup.


The usual steady refinements to our coverage of the GtkTreeView API continue. There’s a new DataColumn type for Stock icons, and TreeModelSort is now implemented.

and minor changes to various other miscellaneous classes:

Considerable internal optimizations have been done, especially relating to ensuring proper memory management, with notable refinements to make use of “caller owns return” information available in the .defs data. This fixes a number of bugs. Thanks to Vreixo Formoso for having driven these improvements.

Error handling has been improved for GLib based libraries as well. If an ERROR or CRITICAL is emitted, our internals will trap this and throw an exception instead, allowing the developer to see a Java stack trace leading them to the point in their code where they caused the problem.

Internationalization support

java-gnome now has full support for the GNOME translation and localization infrastructure, including the standard _("Hello") idiom for marking strings for extraction and translation. There’s a fairly detailed explanation in the Internationalization utility class.

Build changes

Note that as was advertised as forthcoming some time ago, Java 1.5 is now the minimum language level required of your tool chain and Java virtual machine in order to build and use the java-gnome library.

Thanks to Colin Walters, Manu Mahajan, Thomas Girard, Rob Taylor, and Serkan Kaba for contributing improvements allowing the library to build in more environments and for their work on packages for their distributions.

The download page has updated instructions for getting either binary packages or checking out the source code.

Documentation, examples, and testing

Refinements to the API documentation continue across the board, notably improving consistency. A large number of javadoc warnings have also been cleaned up.

While not a full blown tutorial, the number of fully explained examples is growing. There are examples for box packing and signal connection, presenting tabular data, and basic drawing, among others. See the description page in the doc/examples/ section.

This code, together with the not inconsiderable number of unit tests and the code for generating snapshots of Widgets and Windows means that a large portion of the public API is tested within the library itself. The number of non-trivial applications making use of java-gnome is starting to grow, which are likewise providing for ongoing validation of the codebase.


You can see the full changes accompanying a release by grabbing a copy of the sources and running:

$ bzr diff -r tag:v4.0.6..tag:v4.0.7

Looking ahead

It’s probably unwise to predict what will be in future releases. The challenge for anyone contributing is that they need to understand what something does, when to use it (and more to the point, when not to!), and be able to explain it to others. This needs neither prior experience developing with GNOME or guru level Java knowledge, but a certain willingness to dig into details is necessary.

That said, I imagine we’ll likely see further Cairo improvements as people start to use it in anger. It shouldn’t take too long until the bulk of the functionality needed for most uses is present in java-gnome. In particular, forthcoming coverage of the Pango text drawing library will round things out nicely.

There are a number of other major feature improvements we’d like to see in java-gnome. Conceptual and design work is ongoing on for bindings of GConf, GStreamer, and even support for applets. Within GTK, there have been a number of requests made for various things to be exposed, for example, the powerful GtkTextView / GtkTextBuffer text display and editing capability. Some of these have preliminary implementations; whether or not any given piece of work is acceptable in time for any particular future release will remain to be seen and depends on the willingness of clients to fund us to review and test such work.

In the mean time, people are happily using the library to develop rich user interfaces, which is, of course, the whole point. We’re always pleased to welcome new faces to the community around the project. If you want to learn more, stop by #java-gnome and say hello!


Debian packages

The java-gnome bindings suite is now available in Debian Linux as

If you need help installing it, see the the Debian page in the download section here.

Compliments to Manu Mahajan for having done the research to develop the Debian package, and thanks to Thomas Girard for having refined Manu’s start and for having seen through the process of getting the package uploaded.


Cairo support

Adding coverage of the Cairo Graphics library is a feature we’ve been working on for about 6 months now, and during the 4.0.7 development cycle we’ve been able to land it in java-gnome!

Cairo is a huge library, of course, but we’ve put enough coverage in place to ensure that things are working. Cairo has lots of convenience functions and tons of obscure uses; no surprise (and no apology) that there’s still lots that will need doing. If you want to help make sure it has what you need, then grab ‘mainline’ and see org.freedesktop.cairo.Context.

Huge thanks go out to Behdad Esfahbod and Carl Worth; Behdad was really critical in explaining some basic Cairo concepts to me started when we were working together at the GNOME Summit back in October in Boston, and during March at the GTK hackfest in Berlin, Carl Worth was awesome for having checked our preliminary APIs and for having helped sorted us out as we were working our way through create some examples.


java-gnome 4.0.6 (12 Feb 2008)

Finding the missing methods.

Most of our effort recently has simply been fleshing out areas of the public API. The focus for this work as been getting the coverage needed to allow us to port some of our in-house applications to java-gnome 4.0. It’s not especially glamorous — if anything it has been tedious as hell — but the result has been a large body of improvements to java-gnome as a whole which we’re pleased to release as java-gnome 4.0.6

The bulk of this development took place on the ‘missing’ branch, so named because that’s where I was working on what was missing :).

Continuing Improvement

Notable public changes include coverage additions to enable key stroke and mouse button handling:

Rather than exposing the int keyvals that bubble up out of the X server, we have wrapped these as constants of type Keyval (thereby being consistent with the rest of java-gnome in our working to the strengths of Java as a strongly-typed language; MouseButton was created for the same reason, helping developers understand just what on earth mouse button “1” is, anyway). Along with ModifierType, this gives enough to deal with the KEY_PRESS_EVENT and KEY_RELEASE_EVENT signals when the developer wishes to deal with key strokes.

We’ve finally gotten around to providing proper coverage of the box packing model which underlies every aspect of how GTK presents user interfaces. To understand the size-request/size-allocation process, you might start with Widget’s setSizeRequest().

We’ve also added coverage for SizeGroup, which, when used in concert with nested VBoxes and HBoxes, can work wonderful magic and is often far better than messing around with Table when doing complex layouts.

After dithering for several releases, we’ve settled on how we’re going to deal with ComboBox and family. The underlying GtkComboBox presents something of a nightmare as it is really two classes in one with more-or-less incompatible APIs. So, not surprisingly, we’ve presented it as two sets of classes, with the text-only convenience API spliced out of ComboBox and ComboBoxEntry into TextComboBox and TextComboBoxEntry respectively.

We’ve added a few new features in our coverage of GTK’s TreeView API, and many other classes involved have also seen improvements. The persistent reference to a row provided by TreeRowReference is now available as is model type TreeModelFilter.

Support for the actual filtering in TreeModelFilter is notable for having been quite tricky. The underlying C library use a function pointers rather than a GObject signal emission, and we don’t have any mechanism to handle that. We do, however, have a fantastic capability to marshal signals, so we dealt with the problem by creating a custom signal and then passing a function which emits it when the TreeModelFilter wants to ask the developer whether to include a row or not.

The new classes include support for TreeModel columns storing long data as well as setting properties of that type:

It should also be noted that most of the methods taking a TreeViewColumn have been converted to taking an argument of type CellLayout (an interface implemented by TreeViewColumn). This has no change to how you use our TreeView API, but was necessary to support ComboBox properly.

Finally lots and lots of minor additions to both public APIs and internals deeper down in the GDK part of the toolkit:

As ever, you can see the full changes accompanying a release by grabbing a copy of the sources and running:

$ bzr diff -r tag:v4.0.5..tag:v4.0.6


We’ve always had HTML JavaDoc for the current stable release at doc/api/ on the java-gnome website. We’re going to change that a bit, though. As fixes to the explanatory documentation happen quite frequently to classes and methods all over the place, we’ve decided to generate the JavaDoc from ‘mainline’ periodically and upload that instead. This means that there will, of course, be descriptions of some methods which aren’t yet available in a released version of the library, but they will clearly identifiable by virtue of having a @since tag showing a version number greater than the most recent release.

The idea of having up-to-date illustrations of the various Widgets has proved popular, and we’ve continued to update the suite of snapshots. Doing that is also tedious, but it does provide a good opportunity to test APIs we are exposing especially where unit tests are less suitable.


Looking ahead

Almost as complex as the TreeView/TreeModel API are GTK’s powerful TextView/TextModel classes, collectively a Widget used to display and edit large text documents. Working out the java-gnome coverage for TextView will take a fair bit of consideration, but TreeView provides a road map, and, as with the coverage in 4.0.5 and 4.0.6 (which was driven largely by existing applications we were porting), we have some significant uses of GtkTextView which will guide us on our way.

The next release will also feature significant work outside of GTK; we should be in a position to merge our coverage of the excellent Cairo drawing library soon, and likewise we have tentative work in place letting people store configuration and settings data in GConf. Both the ‘cairo’ and ‘gconf’ branches need more QA and documentation work, but they’re looking good and will definitely be featured in java-gnome 4.0.7.


java-gnome 4.0.5 (26 Nov 2007)

TreeView is here!

It’s always a great feeling when you bag a milestone, and with this release we have reached a major goal on our way to having outstanding Java bindings for the GNOME platform: coverage of GTK’s powerful yet complex TreeView & TreeModel API.


TreeViews are a central part of almost every application. GUIs use lists for all sorts of things, and so a significant goal was to make coding TreeViews and their backing TreeModels as straight forward as possible.

The most challenging and complex part was to design the Java side API, which was no small matter. As a native library, the GtkTreeView API is complex and very much written with programming in the C language in mind, and as such our algorithmic mapping of the underlying libraries into Java doesn’t entirely fit. Long experience with the TreeViews in the previous bindings had made it clear just how nasty to use the API could be, and so the hardest part of the work was to come up with a mapping and a usage pattern that would be both faithful to GTK and be sensible to use.

The other significant challenge was to document the work effectively. Our Java side API documentation is a major feature of java-gnome, and merely exposing classes and methods is not sufficient; they need to be clearly explained in our JavaDoc as well. Introduced in this release, then, are:

along with numerous test cases in our unit test suite, and several comprehensively worked examples.

This was a monster patch, and the culmination of not just three months direct effort, but also where we’ve been heading since we first started the re-engineering of Java bindings for GNOME. Although largely written by Andrew Cowie, a significant contribution was made by Srichand Pendyala who not only exhaustively evaluated the design but also threw in some serious chunks of code. The work benefited from comprehensive input from Peter Miller on the modelling and design, and the comments of Bryan Clark, Owen Taylor, and Hanna Wallach were all really positive and helped us know that we’d gone in the right direction. Finally, thanks to Behdad Esfahbod and the GNOME Foundation who made it possible for us to meet in Boston at the GNOME Summit and so accomplish much of the final pulling together of this branch.

Continuing Improvement

Meanwhile, steady work continues on to the fundamental base classes, with a whack of additional signals and methods on Widget and especially Window, along with expansion of coverage in numerous other classes:

What else? We’ve begun to get the basics of image handling in place,

One nice piece of contributed work came from Vreixo Formoso and Thomas Schmitz with coverage of the Dialog Window functionality in GTK. It took a bit of doing to map the int response codes used by GTK into something suitably strongly-typed, but all good:

And finally, minor improvements to all sorts of stuff:

notably from new contributor Mario Torre. Awesome!

For further details you can always grab a copy of the sources and run

$ bzr diff -r tag:v4.0.4..tag:v4.0.5

to see the complete code delta.


For fun we built in a capability to create demonstrations to be captured as screenshots to illustrate various things. It doesn’t get more basic than the example on the Window documentation page, but it’s a nice touch. :) We’ve screenshots for a number of Dialog classes and one for the TreeView page. I imagine we’ll build up a nice library of images in the next few months (yes, dear contributors, you can add snapshots to the list of things we’ll be expecting along with well written documentation and unit tests when submitting additions to the public API).

Building and requirements

The library now depends on GTK >= 2.12. Those packaging java-gnome for their distributions please take note.

Looking ahead

Continuing to expand the coverage levels in the classes already exposed will continue to dominate our attention; there’s still a long way to go but we’re pleased with the progress we’ve made so far; you can definitely build real applications with java-gnome now.

The next release also ought to include preliminary coverage of GConf and Cairo. Doing each justice will again take a serious amount of work, but will continue to grow the fun things you can do with java-gnome.


Arch packages

java-gnome now builds on Arch Linux and is packaged there. Thanks to Timm Preetz for having done the legwork for this!


Trees and Branches

Lots of ongoing work.

The major focus over the last three months has been on the ‘treeview’ branch. Andrew Cowie, backed by Srichand Pendyala, has made awesome progress in working out the engineering necessary to support GTK’s powerful but complex TreeView/TreeModel system and designing an appropriate public API by which java-gnome can present it. This has taken most of September and October but is working really well at this point. This branch should be ready for merging to ‘mainline’ in the next week or two; just need to bring the documentation up to release quality and we’re set.

Vreixo Formoso and Thomas Schmitz have done some great work to expose the Dialog family of classes. This work has exposed a few bugs in our internals, but thanks to some expert help from Owen Taylor we should have that sorted out soon. Work to fix that is taking place on the ‘delete’ branch.

Andrew Cowie, helped by Behdad Esfahbod, has begun work on a binding of the Cairo library. This work is still experimental at this stage, but we’ll merge this ‘cairo’ branch in so we can to at least set the tone for what will be an exciting addition to java-gnome over the coming months.

Once we land these branches we should be able to polish things up for the release of 4.0.5, hopefully by the end of November.


java-gnome 4.0.4 (26 Sep 2007)

Coverage increasing!

Most of our work continues to be on infrastructure and architecture, improving the code generator that outputs the translation Java layer and JNI C layer which allow bindings hackers to reach the underlying native libraries. Nevertheless, there have been a number of publicly visible improvements across the board, so we wanted to push out a release highlighting these contributions!

Documentation improvements

Continuing our effort to have extensive developer friendly tutorial style documentation, there have been major additions to a number of existing classes. Of particular note is the Window class, containing the various utility methods used to ask the window manager to do things for you (we’ve also started exposing some of the deeper parts of the GTK toolkit, though only a few things that were immediately related to window management).

While the topic of thread safety was discussed at considerable length in the last release, we have added some of the more relevant information to the code documentation to reinforce its importance.

New coverage

Numerous people have been hard at work developing new coverage. The standards for accepting patches which expose public API are high, so it’s awesome to see bundles accepted for being merged to mainline from new contributors Thomas Schmitz, Wouter Bolsterlee, and Nat Pryce.

The infrastructure for a number of areas important to supporting applications including Menus, Toolbars, and Actions has been put in place:

A number of Container related Widgets have been added, though coverage is preliminary. There have, of course, also been a number of minor improvements in other existing classes, including:

and even:

Along with these goes a variety of miscellaneous constants and wrappers around the stock item identifiers:


Vreixo Formoso carried out an important refactoring to the type database and Generator family of classes in the code generator, with the result that more of the array passing and out-parameter cases are now being handled correctly. This kind of work is usually thankless and taken for granted, but it’s hugely appreciated!

The real gains are in internal quality. A number of serious bugs and limitations have been overcome (Glade is working again, for example). The generated code now guards against improper use (you can’t pass a null pointer unless it’s allowed by the underlying library). Related to this is handling of “GError” — Java side, bindings hackers will get GlibException which they can then re-throw as an appropriate Java Exception, say FileNotFoundException in the case of not being able to open a file.

This all goes along with numerous build system fixes by Srichand Pendyala to make for an increasingly robust project. Thanks guys!

Looking ahead

As mentioned above, we have mostly been focused on areas other than public API, but it is expanding steadily. The hard work on infrastructure, however, is starting to pay off, and the next release should include coverage of TreeView, GTK’s powerful but complex list Widget.


Gentoo packages

The java-gnome bindings suite is now available in Gentoo Linux. An .ebuild for 4.0.3 has been merged to Portage in

If you need help installing it, see the the Gentoo page in the download section here.

Thanks to the people who pushed this through: Xerces MC for having submitted an initial .ebuild, Petteri Räty (Gentoo dev and Java team lead) for having fixed it up, and Christoph Brill for testing.


java-gnome 4.0.3 (31 Jul 2007)

The code generator has landed!

Work has been underway for several months to develop the next stage of the new java-gnome: the code generator that will output the tedious translation and native layers that allow us to glue our public API to the native GNOME libraries. With this release we’re pleased to announce that the code generator is a reality!

Generated translation and JNI layers

The primary goal of the java-gnome 4.0 re-engineering effort has been to switch to an architecture whereby we could generate the bulk of the machinery necessary to take make native calls into the GNOME libraries from Java.

Extensive prototyping was done to establish the detailed design and to validate the architecture we had developed. Releases 4.0.0 through 4.0.2 contained this work along with mockups of the “translation” layer (the Java code that downshifts from our Proxy objects to primitives suitable to pass over the JNI boundary, along with the native declarations necessary in order to call methods actually written in C) and of the “JNI layer” (the C code that implements the methods declared in the translation layer which in turn coverts parameters into GLib terms and then makes the actual function call into the appropriate GNOME library).

With a solid foundation proving that our design was sound, we subsequently began the long effort to implement a code generator which would output these Java and C layers, allowing us to replace the mockup/ directory and at last leave behind the shackles of entirely hand written bindings. Over the past five months, the java-gnome hackers have been steadily working on the ‘codegen’ branch. The nature of the challenge meant that we had to have most of the code in place before any of it would be useful — never an enviable task to be working on. Thanks to the hard work of Andrew Cowie, Vreixo Formoso Lopes, and Srichand Pendyala, we reached the point where the output Java code compiled in May, and the output C code successfully compiled in by the end of June. Tremendous.

We’ve been bug hunting and refining since then, pushing towards the point where we could merge back to ‘mainline’, at last replacing the hand written mockup code. We are today pleased to announce the culmination of that work with the release of java-gnome 4.0.3.

This post on the development of the java-gnome code generator contains further details should you be interested; the file 5a-Architecture.txt in the doc/design/ directory of the source code explains the rationale and origin of the engineering design.

New coverage

Although our focus has evidently been on getting the generator into working order, there have nevertheless been a few minor coverage additions along the way:

which are largely to the credit of Sebastian Mancke for having submitted them and Srichand Pendyala for having fixed up their JavaDoc. There have also been steady improvements to a number of other classes; notably further signals and utility methods exposed in:

along with some preliminary coverage of the lower level GDK event machinery:

As is reasonable given our focus on writing the actual translation and JNI layer generators, most of these present only one or two methods from the underlying native class. Coverage will steadily improve as people contribute their knowledge and experience in documentation form.

People upgrading from 4.0.2 will actually notice that there are stubs for all of the public API classes; this was necessary to make the generated code compile. Most of these are empty as yet.

GList and friends

GList and GSList are the native GLib data structures used to represent lists and are the return type from quite a few methods across GTK. Vreixo Formoso Lopes worked out how to handle and working our wrap/unwrap functions for us to use in the JNI layer made a significant contribution to reducing our blacklisted method count.


We’ve also worked out handling of native types that, while type defined as enums, are actually bit fields. These are used occasionally in GTK to express options; two examples now exposed are:

Flags subclasses present an or() function allowing you to combine individual Flags constants into a new composite Flags object. Yes it’s a lot of machinery to do a logical |, but being strongly typed is a hallmark of java-gnome.

Build improvements

No release would be complete without mentioning that the code builds on more systems than it did before! Thanks to Maciej Piechotka and Srichand Pendyala for fixing problems resulting from Debian and Ubuntu strangeness.

The build internally now uses an optimized script that takes into account that even though the code generator may have run the translation and jni files may not actually be different. This was causing problems as Make only looks at file modification time. Instead, build/faster (great name, huh?) will only rebuild a target when source contents have changed. This was necessary for bindings hackers working in Eclipse; every time a file was saved Eclipse would merrily spawn off an auto-build which sooner or later would block the IDE UI. Yuk. Addressing this has also resulted in a faster build for everyone; all good.

The internal build script should be transparent; you still run ./configure and make as before. If you experience problems let us know.

Thread safety

In addition to the code generator, java-gnome 4.0.3 incorporates a comprehensive thread safety strategy.

None of the major Java graphical toolkits out there let you make GUI calls from threads other than the “main” one; they’re all single threaded. Even if all you want to do is a quick worker thread to carry out some input validation in the background after the user presses “OK”, you have to jump through horrific contortions to do so safely, resulting in cumbersome, clunky code.

By contrast, the new Java bindings of GTK presented in java-gnome are transparently thread safe, the first and only graphical user interface widget toolkit for Java to be so! We integrate properly with the underlying GDK thread lock and as a result you can safely make calls to various GTK methods from worker threads! This has been a long sought after goal and we hope a significant contribution to helping developers write elegant code.

Every call made to the native libraries is protected by entering the “GDK lock” [that’s gdk_threads_enter/leave() for those familiar with the C side of things]. The lock used is actually a Java side synchronized monitor and therefore reentrant; nested calls all behave properly. When in a signal handler callback the GDK lock is already held (you’re “in” the main loop when a callback happens), but since it just works transparently you don’t need to worry about it. If you do find a need to take the lock into account explicitly in your own code, see Gdk.lock in org.gnome.gdk.

It is worth noting that we have been warned that there are certain to be places in the underlying libraries that do not yet live up to the requirements of the GDK threads model — thus we will likely end up tripping over such things as we slowly add API coverage. We regard such inevitable instances as an opportunity to help contribute to improving the stability of the underlying libraries and will actively work with their maintainers to identify and resolve such issues. Nevertheless, in testing thus far our multi-threaded use of GTK has been rock solid. See these posts on GTK thread “awareness” and java-gnome’s thread strategy if you wish further details on our approach to the thread safety question.

Thanks in particular to Owen Taylor for having helped us navigate these waters!

Looking ahead

Taken together, these innovations represent the culmination of an immense amount of work towards realizing java-gnome as a viable platform for GTK and GNOME development.

Obviously with the generated translation layer in place the opportunity at last exists to start dramatically improving our coverage level, and we welcome contributions to this end. Prospective hackers are cautioned, however, that simply wrapping generated methods is insufficient — public API will only be added when it is clearly documented and meets the approachability criterion.

There are still areas where the code generator needs to be improved; we need to improve our handling for arrays, lists, and out-parameters — there are numerous permutations with all sorts of ugly corner cases.

Now that Free Java with support for generics is becoming widely available, 4.0.3 will be the last release holding the language level to Java 1.4; starting the next cycle 1.5 will be the minimum language requirement and we will be leveraging generics and other 1.5 features from here on.

Most importantly, the primary focus of the next few months will be developing a quality binding for the backbone of many applications: the TreeView Widget and the underlying TreeModel which powers it. The APIs in the native library is hideously complicated and has long been the source of confusion and pain for developers in C; it has long been a major goal amongst the java-gnome hackers to present a public API with as friendly and usable an interface as possible. It’ll be a good challenge.


java-gnome 4.0.2 (12 Feb 2007)

The End of the Beginning!

Major bugfixes and refactorings

Setting and getting properties on GObjects requires some tricky manoeuvring. We implemented the code to do this early on, and it looked like our general mechanism for getting Proxy instances for arbitrary pointers was working fine for properties. It turns out, however, that when you call g_type_name() on a GValue containing a GObject, it returns the name of the type that was listed when the property specification was registered, rather than saying it is a GValue (as you might expect) or what the object actually is (that you might also reasonably expect).

This led to all kinds of nastiness since the type name was what we were using in our instanceFor() mechanism to discriminate (on the Java side) what kind of Proxy subclass to create. The example we tripped over was asking for the parent property of a Button packed into a VBox. What g_type_name() told us was “GtkContainer”, not “GtkVBox”! And that was a big problem, because Container is abstract, and besides, we want to instantiate a concrete VBox Proxy, not a Container one!

Solving the problem involved major changes to:

The solution basically boiled down to having two separate code paths: one named objectFor() [a greatly simplified version of the previous instanceFor()] which returns normal Proxy objects for GObject subclasses (Buttons and Labels and whatnot), and a new code path available via valueFor() to specifically return our GValue Proxy for the cases where we know we’re getting a GValue back. Since that occurs in limited and known circumstances only (ie, when we’re getting properties) it’s no problem to know which to use when.

Thanks to Davyd Madeley for extensive debugging assistance, and credit to Manish Singh, James Henstridge, and Malcolm Tredinnick for having analyzed the root cause issue and having clarified that two code paths would indeed be necessary.

As often happens when you kick a stone loose, we were able to do a number of refactorings to clean things up. This eventually led to the realization (ok, epiphany) that our treatment of the GValue mechanism was needlessly complex. Toss. We no longer have individual Value subclasses for each different fundamental type, but rather just leave them as opaque references:

This allowed a further simplification of the valueFor() mechanism and even more smashing about in Plumbing with a chainsaw. Net result was a reduction by several hundred lines of code. Yeay!

All of these changes were confined to the internals of the binding machinery and are not user visible.

Loading .glade files

User interface designers are nothing new, but one of the really cool things about GTK has long been the existence of libglade. It’s a library which takes the output of a one of the GNOME user interface designers (such as such as Glade 3 or Gazpacho) and dynamically, at runtime, generates live Windows full of Widgets!

With the arbitrary Proxy retrieval sorted out, the beginnings of a binding of libglade was possible. None of the fancy stuff is there yet, but a .glade file can be loaded, and Widgets retrieved from the instantiated tree.

The JavaDoc for these classes clearly indicates that this is preliminary and subject to change. It may well all be blown away when GtkBuilder lands. We’ll see.

Testing framework

We’ve introduced the beginnings of a unit test framework. At the moment, this just evaluates various getters and setters without doing anything that requires the main loop. Despite this, the unit tests end up exercising the entire Proxy system discussed above; validating that the properties set and get and that the correct Proxy object is returned through a round trip is no mean feat.

You can run the suite from Eclipse, by specifying a JUnit 3 launcher on class UnitTests in the default package in tests/java, or by running

$ make test

from the command line.

Further coverage

This release also sees the addition of:

Along with mocked up code for:

This is significant because GtkFileChooser is an interface in GTK, and GtkFileChooserButton implements it. We’d been putting off the question of dealing with GInterface (would it work or be a major problem?) for a while now. We were delighted to find that the design implied by the re-engineered bindings handled it cleanly, elegantly, and without any fuss. Another nice validation of our new architecture.

Finally, a number of new signals were exposed on:

though these were mostly the result of doing live demonstrations at conferences of how easy extending the coverage of the new bindings is.

Memory management

We have successfully implemented full GObject memory management in java-gnome 4.0 using GLib’s ToggleRef mechanism.

A strongly referenced Java Proxy will not allow its GObject to be destroyed out from underneath it; meanwhile, as long as the GObject is still referenced by something other than java-gnome, an otherwise only weakly reachable Java object that Proxies it will not be finalized. When the situation does occur whereby the GObject is only referenced from java-gnome, and the Java object is no longer strongly referenced by any other Java objects, then the Java object can be garbage collected and the GObject will be unref()’d and destroyed.

You can watch the reference system in action if you set Debug.MEMORY_MANAGEMENT to true.

Huge thanks go to Vreixo Formoso Lopes who collaborated on the design, reviewed the implementation, and contributed test case code.

Build system improvements

A better detection of jni.h is done on Ubuntu, thanks to Michael Kedzierski. This makes java-gnome more likely to build out of the box on Debian-derived systems.

On the eve of release, Srichand Pendyala noticed that if you are running such a system, a package named libglade-dev needs to be installed. Of course, on more modern systems all the necessary dependencies are present merely by having GNOME installed in the first place. We’ll add a check for this Debian specific behaviour in 4.0.3.

The VERSION and APIVERSION constants were moved to

so that anyone working on the Gtk main class isn’t forced to do a re-configuration every time they save.

Installation and Packaging

java-gnome 4.0 now has the standard make install command, and the equally standard --prefix option to ./configure.

$ ./configure --prefix=/usr
$ make
$ sudo make install

The install target understands the DESTDIR variable used by packagers to install to a specified prefix within a temporary directory.

See the README file for details.

Looking ahead

The feature additions described above were done to bring java-gnome up to speed for the GTK & GNOME tutorial given at With that past, we’re not going to do any more manual mockups of code in what will be the generated layers. Focus now turns to designing and implementing the tool that will parse .defs files and output the translation code.

Once we secure funding for the project, the code generator will be our top priority and shouldn’t take more than a couple months to complete.


java-gnome 4.0.1 (05 Jan 2007)

It’s not really a prototype anymore! the design works, and so the code that is here is forming the foundation of the new Java bindings for GTK and GNOME.

While there are some significant pieces of engineering that are yet to be done, and of course a universe of coverage yet to write, we’re pleased to mark the milestone of the prototype having proved itself to be stable and the strong foundation that we need. In this release:

Project documentation

Import project documentation, initially consisting of the re-engineering emails written by Andrew Cowie to the java-gnome-hackers mailing list, and expanded to include top level README and HACKING files, and a style guide for contributors to follow. All documentation [re]formatted in Markdown syntax so as to be renderable to web pages. See doc/design/ and doc/style/.

Project website

Create an entirely new website for, introducing sections “About”, “Documentation”, “Download” and “Interact” to discuss the the project as a whole, to be a home for the documentation, to provide instructions on how to get java-gnome, and information about the mailing lists and IRC channel, respectively.

The website is no longer a wiki but is entirely within the source code of java-gnome itself. See the web/public/ directory; improvements welcome.

Major engineering

Quite significantly, the infrastructure to get a Proxy or Constant instance for any arbitrary C side pointer or enum is complete, involving significant work to:

Along with the corresponding C side code, especially in GValue.c

This was a necessary building block in order to complete the generalized getProperty() mechanism that, while hidden from public view, is nevertheless a major aspect of the GObject tool chest and is usable by bindings hackers when necessary. The generalized instance mechanism was the last major engineering hurdle that needed to be achieved in order to prove the new bindings design.

New coverage

Along with

And corresponding [working] mockup native code.

Compliments to Srichand Pendyala from Bangalore, India for being the first external hacker to have a patch accepted to mainline! He contributed methods to Label and initiated the implementation of the Fixed class. In so doing, he also helped work the bugs out of the bzr bundle submission process. Awesome.

Build improvements

java-gnome now builds on Ubuntu and OpenSolaris in addition to its home turf of Gentoo. Thanks to John Rice of Sun Microsystems who provided the guidance allowing us to port Equivalence to Solaris some months ago, and Laszlo Peter, also of Sun Ireland, for several fixes to allow configure to recognize a wider range of Solaris environments.

The tiny example program that we have been using to validate the code, Experiment is now compiled by the build system if you so request. Try make demo.

API documentation

Extensive attention has been paid to the JavaDoc for the few methods that are presented so as to clearly set the standard required. The canonical JavaDoc for the project is available at the website with a stable URL and can be linked to.

All source code [comments, ie JavaDoc] have been spell checked! Initial top level overview.html and package.html files have also been written to help round out the JavaDoc.


java-gnome 4.0.0 (26 Nov 2006)

Initial release of the java-gnome 4.0 prototype, corresponding to the first public demonstration of the new bindings done at at Bangalore, India.

The prototype is fully functional and is intended to prove the design and architecture we have arrived at as a result of the re-engineering process. It includes both real wrapper layer classes that are the seed from which our public API will grow, along with the infrastructure that the wrapper layer depends on.

Initial coverage

Wrapper layer presenting the public API to developers (publicly visible classes in bold):

Along with complete translation layer implementations for each:

At present the bindings mock up the code that will be generated with temporarily hand written substitutes (ie, those in italics above) for both translation (Java) and native (C) layers. These will do until we receive the funding to make the code generator a reality; we certainly don’t want to be writing much more translation layer Java and C code by hand. Yuk.

Signal API

The defining aspect of GUI programming is, of course, that it is event driven. In addition to the “forward” direction of making calls to the native library and having return values bubble back up, there is the “reverse” direction of connecting callback handlers to the various signals that different Widgets offer, and having those signal events result in those handlers being invoked.

java-gnome 4.0 has an entirely new and redesigned signal connection and callback API. This functionality was demonstrated, and coverage of Button.CLICKED and Window.DELETE is now present and functional! The APIs used by GNOME language bindings to achieve this are some of the most voodoo I have ever seen. But it’s hooked up, and it works. It’s like black magic :)


java-gnome is configured and built using Andrew Cowie’s Equivalence build scripts. It builds on Gentoo and should build on a Debian or Fedora derived system as well. See README for further details.

At the moment, java-gnome is a single source package.

The source code is available via bzr. Again, see README.


Contents copyright © 2006-2011 Operational Dynamics Consulting Pty Ltd, and Others. See AUTHORS file and source code history for the various files comprising this site for full details. This page was generated from a text document! We use John Gruber's Markdown syntax as ported to PHP by Michel Fortin. See MARKUP for details