So, after my last blog post, I ended up taking another few months to get the fonts branch just right, but now we have font resource that can be tagged, filtered and searched upon.

After that, I needed my next text editing project to be a bit more manageable. Given that I had already made some head start on it at the beginning of last year, I continued with UI for the OpenType features.

OpenType Features

Usually, OpenType features are explained away as “that’s for ligatures and stuff”, which, while not incorrect, is maybe a little simple. “It enables advanced typographic features” is a little more correct, but it makes OpenType feature support sound less rudimentary than it really is these days.

What might be more clear is to think of a font file as a mapping between input characters and their glyphs. This is fine for simple Latin. But what if you want to show Arabic connected? Well, then you need a second table to keep track of the glyphs for start, middle and end of a word, and substitute the correct glyph as necessary.

Or maybe you want to have kerning, so that A and V nest into each other nicely. Another table for that then, that keeps track of the position adjustment between two consecutive glyphs.

How about small caps? Substitution table. Dynamically placing diacritics? Positioning table. Cyrillic has different glyph traditions in Serbia and Bulgaria, similarly for Han script use in East-Asia: Substitution table. Han script is usually typeset in mono space, but when two brackets follow one another, they often have extraneous white space that should be removed: Positioning table. These are all OpenType features.

The more you look into it, the more it becomes clear that if you want your text layout to support more than plain English, you will need to allow these extra tables to be used and read through. This is in short what Harfbuzz does for us. You can enable and disable these features by taking their name (A 4 letter tag), and indicating to Harfbuzz you want them enabled for a given section by sending a number (0 for off, 1 for on… and 2, 3, 4, […] 256 for indicating which alternate you’d like if the font has multiple alternates available for that feature).

Some of these features are enabled by default, and the basic text layout will process them just fine. However, others are optional, and within CSS all of them can be turned off and on at the typesetters’ wish. Which brings us to the widgets.

CSS font variants

There’s two types of CSS opentype toggles. The first of these are the font-variants, which have a somewhat confusing name in this day and age of OpenType variable fonts, but at the time they were named font-variants were limited to Small Caps, and expected to be separate font files.

The font-variant features more of a guidance suggestion, meaning that you turn them on or off for a piece of text, unrelated to whether the current font actually supports the feature in question. The idea being that you could set a different font elsewhere in the text, and that if this font supports those features, they could be controlled this way.

This means that the UI for these features is somewhat straight forward and unopinionated, being a collection of drop-downs and check boxes. I renamed them “glyphs:” in the UI to avoid confusion with Variable fonts, which is also possible because the majority of them represented which glyphs are being used.

CSS Font Feature Settings and the Glyph Palette

font-variants only cover the most common features, and as of writing, there’s over 120 registered OpenType feature tags. CSS allows controlling this via the second type of properly “font-feature-settings”. A property that wants you to be very specific about which tag you want to enable, and whether you want to have it not just enabled, but also which sub index of the feature you would like to enable.

Now, there’s a bit of a problem here: 120 features is a bit much. Furthermore, two of those registered features, Character Variants and Stylistic Sets, are registered 99 and 20 times respectively, meaning the total is closer to over 230 features. And, further furthermore, fonts may have custom OpenType feature tags.

And that’s not the only problem: Access All Alternates, Stylistic Alternates and Stylistic Sets are very common features, but the way they are configured in CSS as a font-variant feature is somewhat complex, and to have each manually enabled inside the OpenType Features widget is going to feel very clunky for artists.

For these reasons, I ended up building two controls for this CSS property. A main widget for the text property docker that allows artists to enable and disable any OpenType feature that can be found inside the font, and the second being a glyph palette, that allows artists to select alternate glyphs.

The glyph palette was actually made first, so lets go over that. It is in effect a character selection map that allows artists to select alternates to the current glyph or to any glyph inside the font. Filtering can be done with Unicode blocks and search.

It uses KoFontGlyphModel, a QAbstractItemModel, that collects all the available characters inside the font, as well as their Unicode variations (Unicode variations are an extra code point added behind a character to indicate it needs to be a specific version of that glyph. It’s main use is to ensure people’s names are written with the correct glyph variant).

It then takes the locale of the text, and uses those to go over the OpenType tables with Harfbuzz. The locale of the text, or “text language” is necessary because some OpenType features are only available for certain locales. Furthermore, the aforementioned Character Variants and Stylistic Sets may have been named inside the font, meaning that it also takes the interface languages to get the correct name for the current localization of Krita.

Of course, using these alternate names means we need default names first. Which is why I also spend some time on creating a factory where each known OpenType tag is stored with its proper name from the official registry and a hand written summary of the feature for the tool tip. These can now be localized.

Then when we have the feature, we go over the glyphs marked by the table and if that glyph coheres with a Unicode code point, add the table as a potential sub glyph for that Unicode value.

Now here another problem rears its head: We need to know which glyph coheres with which Unicode code point, and while for basic values that isn’t a problem, it is when decomposition comes into play.

Decomposition in this case, is a feature that allows for replacing a given glyph with two other glyphs. A reverse ligature, if you will. It is frequently used to match Unicode decomposition: Ä according to Unicode can be decomposed into A (U+0041) and ◌̈ (U+0308, combining diaeresis). So then, the glyph for Ä can be decomposed into those two glyphs. Afterwards, OpenType allows positioning that diaeresis accurately with the mark positioning feature. This is useful, because we can then take that A glyph, and use things like the Small Caps feature, or a Stylistic Set to turn it into a small A or a decorative A, and as long as these alternate glyphs have been configured for mark positioning, they’ll by themselves support Ä.

So that’s pretty neat. But the problem is that Harfbuzz doesn’t provide enough information for me to discover how a glyph gets decomposed. Meaning that for fonts that are structured this way, I can’t tell whether style sets or the like can be applied to these glyphs, so these don’t show up in the character map. I have a similar problem with ligatures, but that is also compounded by having trouble with the user interface.

For the glyph palette, the way you use it is either by using the glyph alternates, where double clicking one will replace the current grapheme (that’s a set of Unicode values that is often treated as the smallest editable chunk of text) with one that either has the appropriate Unicode variation selectors attached, or one that has the appropriate OpenType features enabled.

The other option is to use the character map, which is much like character maps in other software, allowing you to scroll over all available Unicode values in a font, and sorting them by Unicode block, or searching them. Clicking on a glyph with variants ops out a context menu with the glyph alternates.

The glyph palette itself is written with QML, but because the rest of Krita is not in QML, it is embedded into a QQuickWidget, that is inside a QDialog, which in turn means the context menu needed to be inside a QQuickWidget inside a QPopup, because QQuickWidget will clip any QML pop-up items. QML side, we use DelegateModel to show the child indices of a given character map index.

I’m not sure yet how ligatures would be handled here, maybe list them for each glyph, or maybe have a separate model that shows up underneath the glyph alternates and only shows for the current text. There’s also the fact that stylistic alts and the like can apply to ligatures, so that’s another thing to consider. A similar issue is with emoji zero-width-joiner sequences. This is stuff like “fireman + woman + Fitzpatrick skin tone modifier 5” = . This is typically implemented as a kind of ligature as well, and while Unicode keeps a list of these, I’d prefer to get them from the font.

For the “OpenType features” control in the text properties docker, we reuse the glyph model, but this time its only to figure out which features are available in the font. Because CSS allows for font fallback, we only do this for the first font, but also allow setting any other officially registered OpenType feature on or off. It also shows a sample for the given feature. This widget is mostly useful for the stylistic sets and the positioning features.

Speed-ups

Now, setting up the glyph model can get quite slow, so some trade-offs were established:

• The glyph palette right now only shows a handful of substitution features, to avoid slowing down initialization. These also decide the sample depicted in the OpenType features drop down.
• When a sample is retrieved, it is limited to the first 6 entries. This should be good enough, because the main purpose is to indicate something is going to happen when selecting this feature.
• The QQuickPaintedItem that draws the glyph uses our text layout under the hood, which on one hand is good: this means we always draw something we can show in our text layout. But at the other end, we had to disable some conveniences, like the dynamic fallback (possible because we always know if an input text can be rendered), as well as disabling automatic relayout.

Final Thoughts

One of the things that struck me when writing the original svg text layout post a few years back is that a decade ago, you’d really boast about your OpenType support, but nowadays, OpenType support is so rudimentary, it didn’t make sense to dwell on it in that post. This might also be a consequence by how easy Harfbuzz makes using OpenType these days.

That meant I really wanted to get the UI for this feature nice. There was a big post over a decade ago by a UI designer doing UI for free software, where he went into extensive detail about how most software implementing controls for OpenType features is really bad at communicating whether the feature does anything. I think I managed to somewhat get that part working right.

Still, the glyph palette could use more love, and I really need to sit down for the whole ligature UI issue. I’m pretty happy with it none the less, and it is very hackable, meaning that it doesn’t necessarily need to be me personally improving it.

I do need to really get going on that language selector though…

Appendix

About the font scanning code

The code for retrieving the OpenType tables was largely based on Inkscape’s, and then extended. Inkscape doesn’t test on language, and only tests for substitution features, while we test on both substitution and positioning features. Similarly, Inkscape’s was written in a time when Harfbuzz could only give information about whether a feature could be turned only on or off, but not whether it had multiple alternates, so it is not yet able to do that.

Of interest is that Inkscape does show a few ligatures, but the only reason those are visible is that there’s a handful of ligatures that are encoded into Unicode in the “Alphabetic Presentation Forms” block. Fonts that implement ligatures tend to also setup these Unicode values, but this is not self-evident, which is why I’d prefer not doing this.

(As a random factoid: Adobe’s Smart Quote feature will use these Unicode encoded ligatures when the font isn’t able to provide them via OpenType.)

I did manage to get ligature samples by simply testing every combination of glyphs that Harfbuzz could tell me were probably relevant to a given table, but this was slow, leading to a 5~ second initialization time on a feature heavy font like Junicode. Maybe the glyph model code can be at some point modified to allow incremental loading, though that wouldn’t provide me a quick sample text in the text properties docker…

Shaping Technology

I feel I should probably mention that OpenType isn’t the only technology that provides shaping. Apple’s Advanced Typography Tables (ATT) and the Graphite shaping language are existing alternatives, but OpenType is far more popular than either, and the CSS working group doesn’t give much guidance on how to use anything but OpenType.

Widgets and Items

Qt currently has two UI toolkits: QML and QWidget. The former uses the terminology “Item” instead of “Widget” to refer to UI controls. I find this somewhat difficult to get used to, so when I don’t prepend a widget name with Q, assume that I mean a generic UI control. I think most people never even consider what the different UI bits are called, so usually it isn’t a problem.

Just a quick update: Recently, you might have heard that GTK 4 added support for the cursor-shape-v1 protocol on Wayland. The main advantage of the cursor-shape-v1 protocol is that it ensures consistent cursor look between apps. In Plasma, additional perks come with it, for example the cursor can look more crisp with fractional scale factors because SVG cursors are used. We (KDE) took a shot at backporting the cursor shape protocol support to the GTK 3 branch and, as of this moment, it’s already merged . This means that you should experience fewer cursor issues in applications running on Wayland that still use GTK 3, mainly Firefox.

I would like to express many thanks to Max Qian for starting the work on adding support for the cursor-shape-v1 protocol, and Matthias Clasen for pushing it over the finish line and reviewing our backport MR.

Qt’s 3D offering is changing, so we decided to look at different options for rendering 3D content in Qt.

Continue reading 3D Rendering Solutions in Qt – an Overview at basysKom GmbH.

I have one desktop machine, my daily-driver, which runs FreeBSD 13 – the latest supported version is 13.5 – and which I want to keep on KDE Plasma 5 (and all the rest of the last-gen KDE things). I do also want a modern KDE Plasma 6 desktop, but I’ll do that on a slightly newer machine. Here’s some notes-for-myself.

The FreeBSD ports tree is branched every quarter, roughly with the idea that you can pick a stable(-ish) branch of ports to consume, or you can go with main and get the ports-du-jour. The branches also offer a way of sticking to older releases of some software.

KDE Plasma 6 (and most of KDE Gear, and all the supporting KDE Frameworks) have arrived in main, and the KDE Plasma 5 ports have been removed. That’s a decision of the kde@ group of maintainers of the KDE ports in FreeBSD, one which boils down to not having the time available to maintain both versions, and wanting to be able to upstream fixes.

But I want to stick with older KDE software, at least on my daily driver, a little longer. Oh, and I want a recent Telegram port. And a pony, too.

Previous-generation Stuff

KDE stuff is simple to do:

• Check out the ports tree, e.g. git clone https://git.freebsd.org/ports.git
• Switch to the last branch that has KDE Plasma 5-era software, e.g. git checkout 2025Q1
• Build KDE software, e.g. use poudriere(8) to build the port x11/kde5

Some additional things that I use also work from that ports branch:

• Firefox
• LibreOffice

Somewhat surprising (to myself, anyway) was that Telegram, a desktop instant-messaging client, was not a very-recent version in the branch, but also that the version available in the branch did not even compile. The problem looks like this:

tdesktop-5.10.0-full/Telegram/lib_base/base/qt/qt_compare.h:24:43:
   error: redefinition of 'operator<=>'
   24 | [[nodiscard]] inline std::strong_ordering operator<=>(
/usr/local/include/qt6/QtCore/qstring.h:777:5: note: previous definition is here
  777 |     Q_DECLARE_STRONGLY_ORDERED(QString)

That’s just a clash between the Qt6 bundled with Telegram and the one on the system, but it is rightly annoying. I ended up cherry-picking updates from Telegram 5.10.0 up to 5.10.7 from the main branch (it took a couple of rounds of conflict-resolving, though) which is recent-enough and also builds. Thanks Sergey for maintaining that port.

Next-generation Stuff

Over on FreeBSD 14.2, my “other” machine which I kind of hope to make my main desktop soon-ish, using the main branch from FreeBSD ports gives me fairly-recent KDE software. In this branch, we (as in kde@ in the FreeBSD ports tree) gave up again on KDE version numbers. KDE software is just KDE software – which is also what the KDE community would like us to call it.

Six years ago, I wrote about kde5 which kidded around a bit, but we had x11/kde4 and x11/kde5 side-by-side for a long time. No more. You (metaphorical “you, the person using KDE on a FreeBSD desktop”) get the latest stuff, and it’s just called KDE, and we’re not going to bother with those version labels anymore (which is what upstream has been saying for over ten years now).

Last week, part of the Kdenlive core team met in Amsterdam for a short sprint, the highlight of which was a visit to the Blender Foundation.

Francesco Siddi, COO at Blender, provided us with a rare insight into Blender’s history and precious advice about product management for Kdenlive – we hope to implement some of these advices soon.

As the meeting took place on a Friday afternoon, we also had the opportunity to attend their “Weekly”, which is an open session where artists and developers share their progress of the past week on various Blender related projects.

So thanks again to Francesco and everyone at the Blender Foundation for their hospitality.

On the next day, we discussed a few topics, including:

• Refining the audio workflow task
• Proof of concept on how we can improve clip timecode – define a start timecode when rendering
• Finalized an MLT patch to make rendering work without a display server (required to make Flatpak pass our render test suite)
• Scratched a few itches

Smaller statusbar in Dolphin, CSS Font Variables in Krita, and SystemdGenie redesign

Welcome to a new issue of "This Week in KDE Apps"! Every week we cover as much as possible of what's happening in the world of KDE apps. This time again a bit delayed. If you are a non technical person and are looking at a way to contribute to KDE, you can help editing "This Week in KDE Apps" would be very much welcome. Just join our Matrix chat.

This week we have some big changes in Krita, a redesign in SystemDGenie and a new, more compact statusbar for Dolphin.

Amarok Rediscover your music

We dropped the Qt5 support and moved to Qt6 (Tuomas Nurmi, Link).

Dolphin Manage your files

Dolphin now uses a more compact statusbar by default (Akseli Lahtinen, 25.04.0. Link).

When in selection mode, Dolphin now has a special keyboard navigation mode. You can read all about this feature in detail in the merge request description (Felix Ernst, 25.04.0. Link).

Kasts Podcast application

We fixed various usability issues and recent regressions (Bart De Vries, 25.04.0. Link 1, link 2, link 3, ...).

Kate Advanced text editor

We improved support for DAP (the generic protocol for debuggers) (Waqar Ahmed, 25.04.0 Link), and sped up KWrite's startup time by not loading a MIME database when just querying the icon for text/plain file. (Kai Uwe Broulik, 25.04.0. Link)

Kleopatra Certificate manager and cryptography app

We removed the Decrypt/Verify all files in folder menu item in the Dolphin context menu as it was never implemented (Tobias Fella, 25.04.0. Link).

Konqueror KDE File Manager & Web Browser

The Save As dialog now remembers where a file was last downloaded and will open that directory. Note that the last location is only remembered for the duration of the Konqueror window (Stefano Crocco, 25.04.0. Link).

Krita Digital Painting, Creative Freedom

We added a glyph palette to choose between alternates or variation of a given glyph, as well as a character map of a given font (Wolthera van Hövell, Link).

And implemented the edition of the CSS Font Variants in the text properties docker (Wolthera van Hövell, Link).

Krita now compiles with Qt6 on Windows (Dmitry Kazakov, Link).

We added a new extension "Mutator". This new extension provides a docker which adds brush variations through action-invoked settings randomization (Emmet O'Neill, Link). We also added global pen tilt direction offset which is helpful to make brushes feel the same for right- and left-handed users (Maciej Jesionowski. Link). Another brush related improvement is that their smoothness is now also affected by the speed (killy |0veufOrever, Link).

Kup Backup scheduler for KDE's Plasma desktop

We improved the link text in the KCM user interface (Robert Kratky - first contribution 🚀, 0.11.0. Link).

NeoChat Chat on Matrix

Long pressing has been disabled on non-touchscreen devices (Joshua Goins, 25.04.0. Link), and we improved the usability of the account menu by giving it a proper button (Joshua Goins, 25.04.0. Link).

Okular View and annotate documents

We have improved the error handling entering a bad passphrase for a digital signature (Sune Vuorela, 25.04.0. Link) and made the overprint preview setting a combobox that gives you the option to choose between "Always", "never" and "Automatic", which is similar to Acrobat Reader. The "Automatic" value depends on the value of HasVisibleOverprint in the PDF metadata (Kevin Ottens, 25.04.0. Link).

SystemDGenie

SystemDGenie was ported to a more "frameless" interface and the statusbar was removed (Thomas Duckworth. Link 1 and link 2).

SystemDGenie shows unloaded and inactive units by default (Thomas Duckworth. Link) and the startup time was sped up by fetching the list of sessions and units asynchronously (Carl Schwan. Link).

…And Everything Else

This blog only covers the tip of the iceberg! If you’re hungry for more, check out Nate's blog about Plasma and be sure not to miss his This Week in Plasma series, where every Saturday he covers all the work being put into KDE's Plasma desktop environment.

For a complete overview of what's going on, visit KDE's Planet, where you can find all KDE news unfiltered directly from our contributors.

Get Involved

The KDE organization has become important in the world, and your time and contributions have helped us get there. As we grow, we're going to need your support for KDE to become sustainable.

You can help KDE by becoming an active community member and getting involved. Each contributor makes a huge difference in KDE — you are not a number or a cog in a machine! You don’t have to be a programmer either. There are many things you can do: you can help hunt and confirm bugs, even maybe solve them; contribute designs for wallpapers, web pages, icons and app interfaces; translate messages and menu items into your own language; promote KDE in your local community; and a ton more things.

You can also help us by donating. Any monetary contribution, however small, will help us cover operational costs, salaries, travel expenses for contributors and in general just keep KDE bringing Free Software to the world.

To get your application mentioned here, please ping us in invent or in Matrix.

Edit 2025-03-17: applications for this position are closed.

KDE e.V., the non-profit organization supporting the KDE community, is looking for a contractor to improve KDE’s Plasma desktop environment in ways that support user acquisition through growth into new hardware and software markets. The Plasma software engineer will address defects and missing features that are barriers to these objectives. Please see the full job listing for more details about this opportunity. We are looking forward to your application.

Fahrenheit, new releases and bugfixes

Welcome to a new issue of "This Week in KDE Apps"! Every week we cover as much as possible of what's happening in the world of KDE apps. This time again a bit delayed due to some personal travel.

Releases

• Kaidan 0.11.0 is out. This new version of KDE's XMPP client brings Qt6 support as well as a few new features.
• Tellico 4.1.1 is out with a few minor fixes.
• Amarok 3.2.2 is out with some minor bugfixes, and improvements for building Amarok on non-UNIX systems and without X11 support.

KDE Itinerary Digital travel assistant

Temperature displayed in Itinerary will now use Fahrenheit units when you set your home country to the USA. (Joshua Goins, 25.04.0. Link)

Kasts Podcast application

Improved the volume button to use an adaptive icon depending on the volume level. (Bart De Vries, 25.04.0. Link)

Kate Advanced text editor

Added a button to clear the debug output in the debug plugin. (Waqar Ahmed, 25.04.0. Link)

Added a button to switch between a normal diff (with only a few lines of context) and a full diff with all the context. (Leo Ruggeri, 25.04.0. Link)

KOrganizer KOrganizer is a calendar and scheduling application

Fixed showing the details of a recurrent event. (Allen Winter, 25.04.0. Link)

Konsole Use the command line interface

Fixed some freezing issues when starting Konsole and any applications using Konsole KPart like Kate. (Waqar Ahmed, 24.12.3. Link)

Merkuro Calendar Manage your tasks and events with speed and ease

Added an option to filter the tasks to only displays the ones due today. (Shubham Shinde, 25.04.0. Link)

SystemDGenie

Ported the editor to KTextEditor. (Thomas Duckworth. Link)

…And Everything Else

This blog only covers the tip of the iceberg! If you’re hungry for more, check out Nate's blog about Plasma and be sure not to miss his This Week in Plasma series, where every Saturday he covers all the work being put into KDE's Plasma desktop environment.

For a complete overview of what's going on, visit KDE's Planet, where you can find all KDE news unfiltered directly from our contributors.

Get Involved

The KDE organization has become important in the world, and your time and contributions have helped us get there. As we grow, we're going to need your support for KDE to become sustainable.

You can help KDE by becoming an active community member and getting involved. Each contributor makes a huge difference in KDE — you are not a number or a cog in a machine! You don’t have to be a programmer either. There are many things you can do: you can help hunt and confirm bugs, even maybe solve them; contribute designs for wallpapers, web pages, icons and app interfaces; translate messages and menu items into your own language; promote KDE in your local community; and a ton more things.

You can also help us by donating. Any monetarnky contribution, however small, will help us cover operational costs, salaries, travel expenses for contributors and in general just keep KDE bringing Free Software to the world.

To get your application mentioned here, please ping us in invent or in Matrix.

The Amarok Development Squad is happy to announce the immediate availability of Amarok 3.2.2, the second bugfix release for Amarok 3.2 "Punkadiddle"!

3.2.2 features some minor bugfixes, and improvements for building Amarok on non-UNIX systems and without X11 support. Additionally, a 16-year-old feature request has been fulfilled. Concluding years of Qt5 porting and polishing work, Amarok 3.2.2 is likely to be the last version with Qt5/KF5 support, and it should provide a nice and stable music player experience for users on various systems and distributions. The development in git, on the other hand, will soon switch the default configuration to Qt6/KF6, and focus for the next 3.3 series will be to ensure that everything functions nicely with the new Qt version.

Changes since 3.2.1

FEATURES:

• Try to preserve collection browser order when adding tracks to playlist (BR 180404)

CHANGES:

• Allow building without X11 support
• Various build fixes for non-UNIX systems

BUGFIXES:

• Fix DAAP collection connections, browsing and playing (BR 498654)
• Fix first line of lyrics.ovh lyrics missing (BR 493882)

Getting Amarok

In addition to source code, Amarok is available for installation from many distributions' package repositories, which are likely to get updated to 3.2.2 soon, as well as the flatpak available on flathub.

Packager section

You can find the tarball package on download.kde.org and it has been signed with Tuomas Nurmi's GPG key.