On deprecations

If you are paying attention to GTK’s git repository, you may have noticed a change in the last weeks.

We have a directory gtk/deprecations, which is destined to contain source files that implement deprecated APIs and will be dropped in the next major release. For the 4.0 release, we emptied it out, and it has been empty ever since. But recently, it started to accumulate files again.

This is a good opportunity to remind folks how we are using deprecations in GTK. But first, lets take a look at the details.

The details, part 1: cell renderers

In GTK 4, we introduced a new family of list and grid widgets that are based around list models: GtkListView, GtkColumnView, GtkGridView. There is also a new combo box implementation using list models, called GtkDropDown. Taken together, these are meant to provide replacements for everything you can do with cell renderers in GTK 3.

The ultimate goal was to remove cell renderers, since they are a whole separate rendering and layout system that tends to interfere with GTK’s CSS and layout machinery, and makes everything more complicated.

But we did not quite get to the finish line for 4.0, mainly because we still had significant uses of treeviews in GTK itself. First and foremost, the file chooser.  Since the filechooser is getting ported to use a GtkColumnView in 4.10, now is the right time to deprecate the cell renderer machinery and all the widgets that use them.

This is a significant amount of code, more than 75.000 lines.

The details, part 2: dialogs

In GTK 4, we dropped gtk_main() and gtk_dialog_run(), since recursive mainloops are best avoided. Again, we did not get to the finish line and could not remove GtkDialog itself, since it is used as the base class for all our complex dialogs.

GTK 4.10 introduces replacement APIs for our ‘Chooser’ dialogs. The new APIs follow the gio async pattern. Here is an example:

GtkFileDialog * gtk_file_dialog_new (void);

void            gtk_file_dialog_open (GtkFileDialog *self,
                                      GtkWindow *parent,
                                      GFile *current_file,
                                      GCancellable *cancellable,
                                      GAsyncReadyCallback callback,
                                      gpointer user_data);

GFile *        gtk_file_dialog_open_finish (GtkFileDialog *self,
                                            GAsyncResult *result,
                                            GError **error);

This may look a bit unwieldy in C, but it translates very nicely to languages that have a concept of promises and exceptions:

try {
  const file = await dialog.open(parent, ...);
  
  ...
} catch (e) {
  ...
};

To learn more about the new APIs, you can look at their online docs: GtkColorDialog, GtkFontDialog, GtkFileDialog, GtkAlertDialog.

With these replacements in place, we could deprecate the Chooser interfaces, their widget implementations, and their base class GtkDialog.

No need to panic

Deprecations in GTK are an early outlook at changes that will appear in the next major release that is breaking API compatibility.  But the eventual GTK 5 release is still far away. We have not even made a plan for it yet.

There is absolutely no need to rush towards ‘deprecation cleanup’. You only need to remove all uses of deprecations when you want to port to GTK 5 – which does not exist yet.

There are still things you can do, though. We are introducing deprecations in 4.10 as a way to give our users time to adapt, and to provide feedback on our ideas. If you want to do so, you can file an issue in gitlab, start a discussion in discourse, or find us on matrix.

In the meantime…

Deprecation warnings can be annoying, but thankfully there are easy ways to turn them off. For the occasional call to a deprecated function, it is best to just wrap it in G_GNUC_BEGIN/END_IGNORE_DEPRECATIONS:

G_GNUC_BEGIN_IGNORE_DEPRECATIONS
gtk_dialog_add_button (dialog, "Apply", GTK_RESPONSE_APPLY);
G_GNUC_END_IGNORE_DEPRECATIONS

If you are sure that you never ever want to see any deprecation warnings, you can also just pass -Wno-deprecated-declarations to gcc.

Inside the GTK font chooser

I’ve written about the handling of fonts in GTK before. This post is going to focus on how to use the more advanced font (and font chooser) features in your application.

Finding fonts

The most prominent end-user feature of the file chooser is of course that you can search for fonts by name, using the search entry:

A more hidden feature is that you can filter the list by various criteria. One criterium is to show only monospace fonts, another is to only show fonts covering a certain language:

A little detail to notice here is that GTK automatically changes the preview text to match the language you are filtering by.

Less is more

The font chooser returns a PangoFontDescription which contains the full details of the selected font: family, style, size, etc. If your application only needs the family, then it is confusing to let the user select a style and size only to have them be ignored.

If this is the case for your application, you can instruct GTK about the font details you need, using gtk_font_chooser_set_level(), and the GtkFontChooserLevel flags:

typedef enum {
  GTK_FONT_CHOOSER_LEVEL_FAMILY     = 0,
  GTK_FONT_CHOOSER_LEVEL_STYLE      = 1 << 0, 
  GTK_FONT_CHOOSER_LEVEL_SIZE       = 1 << 1,
  GTK_FONT_CHOOSER_LEVEL_VARIATIONS = 1 << 2,
  GTK_FONT_CHOOSER_LEVEL_FEATURES   = 1 << 3
} GtkFontChooserLevel;

For example, after

gtk_font_chooser_set_level (chooser, 
                            GTK_FONT_CHOOSER_LEVEL_FAMILY);

the font chooser looks like this:

Much simpler!

Into the abyss

Modern fonts are complicated beasts, and there’s much that’s lurking under the surface. The GTK font chooser can make many of these font features available if you tell it to.

First, there are font variations. These let you continuously vary the characteristics of a font (as long as those characteristics are exposed as variation axes).

 

Typical variation axes are weight, width and slant of a font, but there can others (such as Optical Size in this example).

The selected variations are part of the PangoFontDescription that the font chooser returns, applications don’t have to do any extra work to apply them. Just use the font description as usual.

To enable the font variation support in the GTK file chooser, use GTK_FONT_CHOOSER_LEVEL_VARIATIONS flag:

level = level | GTK_FONT_CHOOSER_LEVEL_VARIATIONS;
gtk_font_chooser_set_level (chooser, level);

More features

Fonts contain not just the glyph contours, but lots of other data that can be applied in various ways when rendering those glyphs. This includes traditional data like kerning and ligatures, but also things like optional glyph shape or positioning variants or even color palettes. Many of these can be enabled by the user with the help of OpenType features.

Here is an example of an OpenType feature for glyph shape variations:


The feature that is toggled on here when going from left to right is called ss12. Thankfully, the font provides the more meaningful name “Single-story g” as well.

This example shows the effect of the frac feature on the display of fractions.

In the GTK font chooser, OpenType features are presented on the same page as variations. As you see, there can be quite a few of them:

Note that Pango treats OpenType features as separate from the font itself. They are not part of the font description, but have to be applied to text either with PangoAttributes or via Pango markup.

To apply the selected font features from a GTK font chooser, call gtk_font_chooser_get_font_features () and pass the returned string to pango_attr_font_features_new().

To enable the OpenType features support in the GTK file chooser, use GTK_FONT_CHOOSER_LEVEL_FEATURES flag:

level = level | GTK_FONT_CHOOSER_LEVEL_FEATURES;
gtk_font_chooser_set_level (chooser, level);

Summary

In summary, you can use the level property of GtkFontChooser to influence the granularity of font selection you offer to users of your application. If you include font features in it, don’t forget to apply the selected features, using PangoAttributes or markup.

All of this is enabled by harfbuzz providing us with a cross-platform API to fonts and all their features. It would not be possible otherwise. It is worth pointing out that this is done by accessing harfbuzz objects directly, rather than wrapping all the harfbuzz APIs in Pango.

 

 

sizable news

For the upcoming GTK 4.6, we have overhauled a lot of the sizing infrastructure to make widgets fit even tighter and to make sure our sizing infrastructure actually does what it says.

halign/valign

When using the GtkWidget::halign or GtkWidget::valign properties, GTK 4.4 would look at the default size of the widget and then place the widget accordingly. This leaves a lot of extra space when one of the values was set to fill. In GTK 4.6, GTK will measure the size of the other dimension relative to the filled dimension. This makes the widget thinner but avoids extra space.

A centered label with empty space in GTK 4.4
A centered label with empty space in GTK 4.4

A centered label with no extra space in GTK 4.6
A centered label with no extra space in GTK 4.6

What if you like the old behavior?

If you do not use fill in either direction, the behavior will be as before. So update the other dimension to not be the default fill and you should get the old behavior back.

GtkBox

GtkBox has learned to assign size to widgets as needed. In GTK 4.4, size was always distributed equally among children that had the same default size. GTK 4.6 will query the children for their actual size to decide which child to distribute how much of the extra size to.

You can see this in the example, where the box was given enough space for 3, 4, 5 or 6 lines of text.

A left-aligned box in GTK 4.4
A left-aligned box in GTK 4.6

GtkLabel

As you could see above, GtkLabel also learned to properly wrap to any given number of lines. This allows labels to take a lot less widths as before, so they no longer take up empty space when they can just line-break.

xalign and halign

It’s worth pointing out that in a lot of cases applications used GtkWidget::halign = GTK_HALIGN_START; when they should have used GtkLabel::xalign = 0.0;. The first aligns the widget as far to the left as possible while the seconds aligns the text inside the assigned space to the left. So if your widgets suddenly look glued to the left edge, you might want to look into that.

GtkWindow

GtkWindow has learned how to adapt minimum size to the aspect ratio. So you can now resize your windows any way you like and they will never get too small, but they will always get as small as possible, no matter if you want to make them flat and wide or thin and high.

a new warning

While doing this work, we figured out that a few widgets do not conform to measuring requirements and added a new warning. So if you see something like:
Gtk-CRITICAL **: 00:48:33.319: gtk_widget_measure: assertion 'for_size >= minimum opposite size' failed: 23 >= 42
It means you have a widget that reports an minimum size for size -1 that is larger than the minimum size it reports for a different size, and that should never happen. You can use GTK_DEBUG=size-request and redirect to a file to find the offending widget. We also added code to work around any problems that warning, but it should be fixed nonetheless. After all, if a widget reports a wrong size, it’s likely it’s doing something wrong.

GTK 4.4

GTK 4.4.0 is now available for download in the usual places. Here are some highlights of the work that has gone into it.

The NGL renderer and GL support

The NGL renderer has continued to see improvements. This includes speedups, fixes for transformed rendering, avoiding huge intermediate textures, and correct handling of partial color fonts. After some help from driver developers, NGL now works correctly with the Mali driver. We are planning to drop the original GL renderer in the next cycle.

Outside of GSK, our OpenGL setup code has been cleaned up and simplified. We increasingly rely on EGL, and require EGL 1.4 now. On X11 we use EGL, falling back to GLX if needed. On Windows, we default to using WGL.

Our GL support works fine with the latest NVidia driver.

Themes

The included themes have been reorganized and renamed. We now ship themes that are called Default, Default-dark, Default-hc and Default-hc-dark. The Adwaita theme is moving to libadwaita.

Among the smaller theme improvements are new error underlines (they are now dotted instead of squiggly) and support for translucent text selections.

Input

Input handling has seen active development this cycle. We’ve matched the behavior of the built-in input method with IBus for displaying and handling compose sequences and dead keys. As part of this, we now support multiple dead keys and dead key combinations that don’t produce a single Unicode character (such as ẅ).

We fully support 32-bit keysyms now, so using Unicode keysyms (e.g. for combining marks) works.

Emoji

Our Emoji data has been updated to CLDR 39, and we can are looking for translated Emoji data by both language and territory (e.g. it-ch).

Debugging

The Inspector is now enabled by default, so debugging GTK applications should be a litte easier.

Windows

Apart from the WGL improvements that were already mentioned, we now use GL for media playback on Windows. A big change that landed late in 4.4 is that we use the WinPointer API for tablets and other input devices now, replacing the outdated wintab API. DND support on Windows is also improved, and the local DND protocol has been dropped.

The numbers

GTK 4.4 is the result of 5 months of development, with 838 individual commits from 71 developers; a total of 88133 lines were added and 63094 removed.

Developers with the most changesets
Matthias Clasen 456 54.4%
Benjamin Otte 82 9.8%
Emmanuele Bassi 48 5.7%
Alexander Mikhaylenko 35 4.2%
Chun-wei Fan 30 3.6%
Christian Hergert 18 2.1%
Luca Bacci 17 2.0%
Carlos Garnacho 10 1.2%
Bilal Elmoussaoui 10 1.2%
Florian Müllner 7 0.8%
Yuri Chornoivan 6 0.7%
Maximiliano Sandoval R 6 0.7%
Marc-André Lureau 5 0.6%
Marco Trevisan (Treviño) 5 0.6%
Pawan Chitrakar 5 0.6%
Piotr Drąg 4 0.5%
Timm Bäder 4 0.5%
Xavier Claessens 4 0.5%
Zhi 4 0.5%
Sebastian Cherek 4 0.5%

The GTK Documentation

As you may have noticed, there have been various changes in the GNOME developer documentation website, as of late. These changes also affected the API references for GTK and its core dependencies.

What has changed

The main change is that GTK moved to a new documentation tool for its API reference and ancillary documentation, called gi-docgen. Unlike the previous documentation tool, gtk-doc, gi-docgen uses the introspection data that is generated by GObject-based libraries to build the API reference. This has multiple benefits:

  • gi-docgen is simpler to run and integrate within an existing library, as it only has a single project description file and relies on the introspection data for everything else; additionally, it can be easily included as a Meson sub-project
  • gi-docgen uses Markdown everywhere, instead of DocBook
  • gi-docgen is considerably faster, as it does not perform an additional source code parsing step; it does not have the bottleneck of the XML to HTML conversion via xsltproc; and it does not have to parse Devhelp files to fix cross-references to other libraries after generating the reference
  • gi-docgen can infer much more information about an API, as it has access to the entire introspection data for a library, including its dependencies; this allows the automatic generation of more accurate and consistent documentation, instead of relying on humans to do this job
  • gi-docgen generates stable URLs for all the API entry points and additional documentation, which means it’s easier to link to and from it without using obscure references
  • the default documentation template is usable on different form factors and layouts; it respects the dark theme options on web browsers that support it; and provides an in-tree live search functionality that does not depend on third party services
  • gi-docgen can also be run out of tree—this will come in handy later

Outside of these improvements, using the introspection data as the source for the documentation has additional benefits: it keeps us honest in the type of API we expose to non-C users; and it makes the C API reference closer to the reference in other languages that consume the same data.

GTK4, Pango, and GdkPixbuf have been migrated to this new tool, and while we were at it, we also reviewed the documentation to improve its consistency and accuracy—especially for the older sections of the API.

The new API references can be used offline through Devhelp 41, which will be released next September alongside GNOME 41.

Online documentation

The canonical online location for the GTK references is now docs.gtk.org. There you will find the API references for:

The API references for GTK3 and ATK have been moved to docs.gtk.org as well.

The docs.gtk.org website is generated by the GTK CI pipeline, so it is always up to date with the state of the repository; thanks to gi-docgen supporting out of tree builds, the website can also generate documentation for various libraries that have not been ported to gi-docgen yet, like GLib, GTK3, and ATK.

Known issues

Of course, with any large change come side effects.

The main issue is the change in the URLs for the documentation; existing documentation referencing locations on developer.gnome.org will have to be fixed. Thanks to the GNOME system administrators we have some redirects in place, and there are ideas on how to improve them without creating an unmaintainable mess of static redirections.

The new documentation website is in the process of being indexed by various search engines; the more you use it, and link to it, the easier it will be for the new references to raise in ranking. In any case, we strongly encourage you to use the search feature: simply press ‘s’ to start searching for symbols and types, or even content inside the extra documentation pages.

Unfortunately, GLib’s introspection data has some issues, given how low level the C API is; we are working on improving that, which will have an impact not only in the documentation but also in the overall bindability of the API in other languages.

The documentation for GLib, GObject, GIO, and GTK3 is also still written for gtk-doc; this means that cross-links in the documentation may not work; the content may not be rendered as nicely; or there can be redundant paragraphs. This will be fixed in the future, both by changes in gi-docgen (wherever possible) and by updating the documentation inside the libraries themselves. This will also improve the language bindings documentation, as they consume the same introspection data as gi-docgen. Help in this effort is very much welcome.

Text input in GTK 4

To wrap up the recent series of posts about input topics, lets talk about text editing in GTK 4.

The simple: shortcuts

Maybe you just need to handle a few keys as editing commands, for example Ctrl-z to undo. In that case, you can just use a shortcut with an action, and set it all up in your widgets class_init:

/* install an undo action */ 
gtk_widget_class_install_action (widget_class,
                                  "text.undo", NULL,
                                  my_undo_func);

/* bind Ctrl-z to the undo action */
 gtk_widget_class_add_binding_action (widget_class,
                                      GDK_KEY_z, GDK_CONTROL_MASK,
                                      "text.undo", NULL);

The complex: a text editor

When you need full text editing, the best approach is to re-use one of the ready-made widgets in GTK for this purpose: one of the entries, or if you need a full-blown text editor, GtkTextView.

If none of the existing entries fit your use case, you can also wrap your own GtkEditable implementation around a GtkText widget, and get all the hard parts of a text editing widget for free. The GTK docs explain how to do that.

The middle ground

But what if you don’t want an entry, but still need to let your users enter individual Unicode characters such as ñ or Å conveniently? I’ll let you come up with a use case for this (although I have one in mind).

One thing you can do is to use a GtkIMContext directly, and let it process key events for you. The way this works is that you attach a key event controller to your widget and connect an input method context to it:

controller = gtk_event_controller_key_new ();
gtk_widget_add_controller (widget, controller);

im_context = gtk_im_multicontext_new ();
gtk_event_controller_key_set_im_context (controller, im_context);

Now key events that reach your widget will be passed to the input method context. Connect a handler to its ::commit signal to receive the completed input:

static void
commit_cb (GtkIMContext *context,
           const char   *str,
           DemoWidget   *demo)
{
  pango_layout_set_text (demo->layout, str, -1);
  pango_layout_set_attributes (demo->layout, NULL);
  gtk_widget_queue_draw (GTK_WIDGET (demo));
}

...

g_signal_connect (im_context, "commit",
                  G_CALLBACK (commit_cb), demo);

You can connect a similar handler to the ::preedit-changed signal to provide the user feedback during preedit like GtkEntry does.

The complete example for single-character input can be found here.

More on input

I’ve written about input before (here and here), and more recently, Carlos and myself gave a Guadec talk about input-related topics (slides). In those writings, I have explained how dead keys work, and how you can type

<dead_acute> A

to produce an Á character.

But input is full of surprises, and I’ve just learned about an alternative to dead keys that is worth presenting here.

Background

First lets recap what happens when you send the <dead_acute> A sequence to GTK.

We receive the first key event and notice that it is a dead key, so we stash it in what we call the preedit, and wait for the next event.  When the next key arrives, and it represents a letter (more precisely, is in one of the Unicode categories Ll, Lu, Lt, Lm or Lo), we look up the Unicode combining mark matching the dead_acute, which is U+301 COMBINING ACUTE ACCENT, and then we flip the sequence around. So the text that gets committed is

A <combining acute>

The reason that we have to flip things around is that combining marks go after the base character, while dead keys go before.

This works, but it is a bit unintuitive for writing multi-accented characters. You have to think about the accents you want to apply from top to bottom, since they get applied backwards. For example to create an  with an acute accent on top, you type

<dead_acute> <dead_circumflex> A

which then gets flipped around and ends up as:

A <combinining circumflex> <combining acute>

A better way

To me, it feels much more natural to specify the accents in that order:

  1. give me an A
  2. then put a ^ on top
  3. and then put an ´ on top

The good news is: we can do just that! Keyboard layouts can use any Unicode character as keysyms, so we can just use the combining marks directly, without the detour through dead keys.

For example, the “English (US,  Intl, AltGr Unicode combining)” layout contains keys for combining marks. A slight hurdle to using this layout is that it does not show up in the GNOME Settings keyboard panel by default. You have to run

gsettings set org.gnome.desktop.input-sources show-all-sources true

to make it show up.

The combining marks in this layout are placed in a “3rd level”. To use them, you need to set up a “3rd level chooser” key. In the keyboard panel, this is called the “Alternative Characters Key”. A common choice is the right Alt key.

After all these preparations, you can now type A Alt+^ Alt+’ to get an   with an   ́ on top. Neat!

Adventures in graphics APIs

Various people are working on porting desktop virtualization UIs to GTK4. This typically involves virgl, and the GTK3 solution was to use GtkGLArea.

With GTK4, rendering is happening in GL anyway, so it should be enough to just wrap your content in a GdkTexture and hand it to GTK, either by using it as a paintable with GtkPicture, or with a GskTextureNode in your own snapshot() implementation.

dmabuf detour

This is a nice theory, but the practice is more complicated – the content is typically available as a dmabuf object, and with 4k rendering, you really want to avoid extra copies if you can help it. So we had to look at the available solutions for importing dmabufs as textures into GL without copies.

This turned into a quick tour through the maze of graphics APIs: OpenGL, EGL, GL ES, GLX, DRI, … the list goes on. In the end, it turns out that you can use EGL  to wrap a dmabuf into an EGLImage, and use the GL_OES_EGL_image extension to create a GL texture from it.

GLX to EGL

This works fine with our Wayland backend, which uses EGL. Unfortunately, our much older X11 backend has a GL implementation using GLX, and there doesn’t seem to be a way to get a dmabuf imported into a GLX context.

So we had to do a little bit of extra work, and make our X11 backend use EGL as well. Thankfully Emmanuele had an old unfinished branch with  such a conversion from a few years ago, which could be made to work (after some initial head scratching why it would not render anything – as always the case when doing GL work).

The solution

It turns out that importing dmabufs with EGL can be done outside of GTK just fine, so we don’t need to add Linux-specific API for it. To save you the trouble of writing such code yourself, here is what I’ve come up with.

After we had already decided to port the X11 backend to EGL, I learned that another possibility for importing dmabufs might be to use DRI3PixmapFromBuffer to create  an X11 pixmap from a dmabuf, turn it in a GLXPixmap and use glxBindTexImageEXT to make a texture.

Aren’t graphics APIs wonderful! :-)

GTK 4.2.0

GTK 4.2.0 is now available for download in the usual places.

This release is the result of the initial round of feedback from the application developers porting their projects to GTK4, so it mostly consists of bug fixes and improvements to the API—but we also added new features, like a new GL renderer; various improvements in how the toolkit handles Compose and dead key sequences; build system improvements for compiling GTK on Windows and macOS; and a whole new API reference, generated from the same introspection data that language bindings also consume.

For more information, you can check the previous blog post about the 4.1 development cycle.

The NGL renderer

Thanks to the hard work of Christian Hergert, the NGL renderer is now the default renderer for Linux, Windows, and macOS. We’ve had really positive feedback from users on mobile platforms using drivers like Lima, with noticeable improvements in frames per second, as well as power and CPU usage; the latter two are also going to impact positively desktop and laptop users. The NGL renderer is just at the beginning: the new code base will allow us even more improvements down the line.

For the time being, we have kept the old GL renderer available; you can use export GSK_RENDERER=gl in your environment to go back to the 4.0 GL renderer—but make sure to file an issue if you need to do so, to give us the chance to fix the NGL renderer.

Input

Matthias wrote a whole blog post about the handling of Compose and dead keys input sequences, so you can just read it. The dead key handling has seen a few iterations, to deal with oddities and workarounds that have been introduced in the lower layers of the input stack.

There is one known issue with the handling of dead acute accents vs apostrophes in some keyboard layouts, which is still being investigated. If you notice other problems with keyboard input, specifically around Compose sequences or dead keys, please file an issue.

Portability

One of the goals of GTK is to have a “turn key” build system capable of going from a clone of the Git repository to a fully deployable installation of the toolkit, without having to go through all the dependencies manually, or using weird contraptions. You can see how this works on Windows, using native tools, in this article from our friends at Collabora.

Additionally, we now ensure that you can use GTK as a Meson sub-project; this means you can build GTK and all its dependencies as part of your own application’s build environment, and you can easily gather all the build artifacts for you to distribute alongside your application, using the toolchain of your choice.

Documentation

One of the most notorious issues for newcomers to GTK has been the documentation. Application developers not acquainted with our API have often found it hard to find information in our documentation; additionally, the style and structure of the API reference hasn’t been refreshed in ages. To improve the first impression, and the use of our documentation, GTK has switched to a new documentation generator, called gi-docgen. This new tool adds new features to the API reference, like client-side search of terms in the documentation; as well as nice little usability improvements, like:

  • a “Copy to clipboard” button for code fragments and examples
  • a visual hierarchy of ancestors and interfaces for each class
  • the list of inherited properties, signals, and methods in a class
  • a responsive design, which makes it easier to use the API reference on small screens

An API is only as good as it allows developers to use it in the most idiomatic way. GTK not only has a C API, it also exposes a whole API for language bindings to consume, through GObject-Introspection. The new documentation uses the same data, which not only allows us to cut down the built time in half, but it also generates common bits of documentation from the annotations in the source, making the API reference more consistent and reliable; finally, the C API reference matches what language binding authors see when consuming the introspection data, which means we are going to tighten the feedback loop between toolkit and bindings developers when introducing new API.

Pango and GdkPixbuf have also switched to gi-docgen, which allows us to build the API reference for various dependencies through our CI pipeline, and publish it to a whole new website: docs.gtk.org. You’ll always find the latest version of the GTK documentation there.

Odds and ends

Of course, alongside these visible changes we have smaller ones:

  • performance improvements all across the board, from GLSL shaders used to render our content, to the accessibility objects created on demand instead of upfront
  • sub-pixel positioning of text, when using a newer version of Cairo with the appropriate API
  • a responsive layout for the emoji chooser
  • improved rendering of shadows in popover widgets
  • localized digits in spin buttons
  • improved support for the Wayland input method protocol
  • improved scrolling performance of the text view widget

The numbers

GTK 4.2 is the result of four months of development, with 1268 individual changes from 54 developers; a total of 73950 lines were added, and 60717 removed.

Developers with the most changesets
Matthias Clasen 843 66.5%
Emmanuele Bassi 124 9.8%
Timm Bäder 87 6.9%
Christian Hergert 33 2.6%
Jakub Steiner 24 1.9%
Benjamin Otte 21 1.7%
Chun-wei Fan 15 1.2%
Alexander Mikhaylenko 14 1.1%
Fabio Lagalla 10 0.8%
Bilal Elmoussaoui 8 0.6%
Carlos Garnacho 6 0.5%
Ignacio Casal Quinteiro 6 0.5%
Michael Catanzaro 6 0.5%
Emmanuel Gil Peyrot 5 0.4%
Xavier Claessens 4 0.3%
David Lechner 4 0.3%
Jan Alexander Steffens (heftig) 4 0.3%
Kalev Lember 3 0.2%
wisp3rwind 3 0.2%
Mohammed Sadiq 2 0.2%
Developers with the most changed lines
Matthias Clasen 38475 42.6%
Emmanuele Bassi 15997 17.7%
Christian Hergert 13913 15.4%
Kalev Lember 9202 10.2%
Timm Bäder 5890 6.5%
Jakub Steiner 2397 2.7%
Benjamin Otte 902 1.0%
Chun-wei Fan 783 0.9%
Ignacio Casal Quinteiro 717 0.8%
Fabio Lagalla 292 0.3%
Marek Kasik 267 0.3%
Alexander Mikhaylenko 254 0.3%
Emmanuel Gil Peyrot 232 0.3%
Simon McVittie 214 0.2%
Jan Tojnar 83 0.1%
wisp3rwind 74 0.1%
Jan Alexander Steffens (heftig) 65 0.1%
Carlos Garnacho 62 0.1%
Michael Catanzaro 61 0.1%
Ungedummt 60 0.1%
Developers with the most lines removed
Emmanuele Bassi 8408 13.8%
Jakub Steiner 1890 3.1%
Timm Bäder 493 0.8%
Simon McVittie 203 0.3%
Emmanuel Gil Peyrot 146 0.2%
Chun-wei Fan 43 0.1%
Jan Tojnar 26 0.0%
Alexander Mikhaylenko 25 0.0%
Jonas Ådahl 17 0.0%
Luca Bacci 13 0.0%
Robert Mader 4 0.0%
Chris Mayo 3 0.0%
Bartłomiej Piotrowski 2 0.0%
Marc-André Lureau 2 0.0%
Jan Alexander Steffens (heftig) 1 0.0%
Tom Schoonjans 1 0.0%

Input, revisited

My last update talked about better visual feedback for Compose sequences in GTK’s input methods. I did not explicitly mention dead keys back then, but historically, X11 has treated dead keys and Compose sequences in exactly the same way.

Dead keys are a feature of certain keyboard layouts where you can hit a key that does not produce a character by itself, but modifies the next key you type. Typically, this is used for accents that can be combined with different base characters. For example, type <dead_acute> <a> to produce á or  <dead_acute> <o> to produce ó.

Traditionally, dead keys were really dead – you didn’t get any visual feedback before the final result appears. With the improvements described in the last update, we now show dead keys as they are entered:

That is a nice improvement. But as it turned out, not everybody was happy.

The shared treatment of Compose sequences and dead keys has some implications: one is that entering a non-existing sequence such as <dead_grave> <x> will produce a beep, and no output. That is acceptable for a Compose sequence that you explicitly started with the Compose key, but not so great when you maybe meant to enter `x.

The people who decided to use Compose sequences for dead keys foresaw the need to actually enter spacing accents every now and then, and added sequences such as <dead_grave> <space> and <dead_grave> <dead_grave> for producing a single ` character.

While that is a nice thought, it is still pretty inconvenient, since you need to type <dead_grave> six time to produce `‍`‍`, e.g. for entering code examples in markdown.

After thinking about this for a while and comparing what other systems do, we’ve made two changes, that will hopefully make dead keys as convenient to use as any other keys on your keyboard.

  • When a <dead key> <key> sequence does not match one of our Compose sequences, commit the individual keys
  • When a <dead key> follows another <dead key>, commit the first one, and treat the second as the beginning of a new Compose sequence

Together, this makes it so that typing <dead_acute> <a> produces á, typing <dead_grave> <x>  produces `x, and you only need to type <dead_grave> three times to enter `‍`‍`:

Much better!