Dear digiKam fans and users,
After four months of active maintenance and many weeks triaging bugs, the digiKam team is proud to present version 8.6.0 of its open source digital photo manager.
The digiKam team has continued to work on a better Artificial Intelligence integration in digiKam, and many parts have been improved with the 8.6.0 release.
One of the biggest behind-the-scenes changes in the upcoming Plasma 6.4 release is the split of kwin_x11 and kwin_wayland codebases. With this blog post, I would like to delve in what led us to making such a decision and what it means for the future of kwin_x11.
KWin started as an X11 window manager almost two and a half decades ago. Over the course of the years, it transformed drastically. It gained support for compositing on X, and it became a Wayland compositor.
Sharing the same codebase was critical in the early days of kwin_wayland. We already had working window management abstractions, which had been tested for many years, so we could reuse them on Wayland instead of writing new from scratch. Also, if kwin_x11 gained a new feature, then kwin_wayland would likely gain it for free too.
As time went by, kwin_wayland outgrew kwin_x11. They still shared code but they became quite distinct projects with different mental models how things operate, e.g. how pixels get on the screen or how input works. It also didn’t help that many Plasma developers jumped the X11 ship and turned to the Wayland side as part of the “eating your own dog food” practice, which eventually led to the feature freeze in KWin/X11 back in 2018 due to the lack of sufficient testing and various breakages.
Some time around 2020, we started taking a more bold and aggressive approach to Wayland session development because we saw that Plasma Wayland was trailing behind other desktop environments and something had to be changed in order to catch up. Such a policy produced great results, and Plasma is now one of the leading Wayland desktop environments. Unfortunately, it also greatly contributed to the number of regressions in the X11 session.
Another issue was that there were some features that we couldn’t make work as expected on Wayland so we had to drop them for everyone, which understandably made X11 users unhappy.
A few years ago, we started contemplating the idea of splitting the X11 and Wayland codebases because of the growing list of regressions affecting the X11 session, and architecture restrictions imposed on KWin/Wayland by the way KWin/X11 works.
That would allows us to keep KWin/X11 working as is without it breaking too often and freely change KWin/Wayland in ways that we think are best suited to make the Plasma Wayland session even better. Of course, it is not a silver bullet solution: we replace one problem with another problem (mainly related to maintenance and ensuring interface compatibility between two projects).
After various discussions online and at Akademy and also seeing (impressive) Plasma Wayland usage statistics, we decided that it’s the right time to do such a split. The main kwin repository is going to host KWin/Wayland, while the kwin-x11 repository is going to host KWin/X11.
KWin/X11 and KWin/Wayland are co-installable so users can freely switch between the X11 and Wayland sessions back and forth and also make sure that updating to 6.4 is not a big hassle for distributions. You’ll be able to have only KWin/X11 or only KWin/Wayland on your computer, or both.
The codebase split doesn’t affect Xwayland support in KWin/Wayland. In other words, X11 applications will continue running on Plasma Wayland.
Like any other Plasma component, KWin’s functionality can be extended using plugins. There’s good and bad news. The good news is that extensions written in JavaScript and QML (for example, fancy effects that are available at the KDE Store) will continue working both with kwin_x11 and kwin_wayland as expected, so extension developers don’t need to do anything about it. The bad news is that C++ extensions should be specifically targeted for kwin_x11 and kwin_wayland because neither provides API and ABI compatibility guarantees for its C++ API.
As Wayland progress moves forward, it is likely that the scripting API of KWin/Wayland will be further extended.
KWin/X11 will be still maintained for the foreseeable future. But that maintenance work will boil down to fixing build errors, adapting to new KDE Frameworks and Plasma APIs, and backporting window-related fixes from KWin/Wayland. There are no plans to drop KWin/X11 in the Plasma 6 lifecycle, although it’s highly possible that it will happen in Plasma 7.
KWin/X11 won’t receive new features anymore; until recently, it received new features that had been developed against KWin/Wayland passively (because both lived in the same repository). However, it might be actually a good thing because the X11 session doesn’t receive that much testing nowadays.
Last week I decided to clean up a bit of digital cruft. That is, I moved a few of my websites onto a single VPS, saving quite a bit of monthly server hosting costs.
What I did was that I moved VPSes from Linode (Akamai) to DigitalOcean, but also migrated a full web hotel from One to DigitalOcean (converting email accounts to email forwards).
As this is something that I do very rarely, I decided to document the process here so that I don’t have to look everything up again next time around.
The grunt work was about migrating a number of L*MP services to a LEMP server. There are a couple of tasks involved here, mainly migration of databases and getting WordPress running in a subdirectory using Nginx. The rest of the exercise had to do with the moving of nameservers and waiting for DNS propagation to get certbot to provide certificates for the new location.
The migration of a database between machines can be broken down into three stages:
I choose to do it in these three stages, as I’d like to keep the old database dump as an additional backup. The other option would be to transfer the database contents in a single step, merging steps 1 and 3 into one
Nevertheless, I use mysqldump to dump the database contents, and then bzip2 to reduce the size of the dump. This is efficient since and SQL dump is quite verbose.
mysqldump -u username -p --databases databasename | grep -vE \"^(USE|CREATE DATABASE)\" | bzip2 -c - > dumpname.sql.bz2
This is derived from the answer by Anuboiz over at stack overflow. The resulting file is then transferred to the new server using scp together with the actual website.
The next step is to create a new database and a new database user. Here, I assume MariaDB (using the mysql commands), as my main target is WordPress. For other database engines, e.g. Postgresql, please check the docs for exact grammar, but the SQL commands should be very similar.
sudo mysql
mysql> CREATE DATABASE databasename;
mysql> USE databasename;
mysql> CREATE USER 'username'@'localhost' identified by 'password';
mysql> GRANT CREATE, ALTER, DROP, INSERT, UPDATE, DELETE, SELECT, REFERENCES, RELOAD on databasename.* TO 'username'@'localhost' WITH GRANT OPTION;
mysql> EXIT
Check out this digital ocean tutorial for details on the above commands.
The next step is to read the database contents into the new database. For this, we need to unzip the sql dump, e.g. bunzip2 dumpname.sql.bz2, which will result in a file called dumpname.sql. Please notice that bunzip2 unzips the file and removes the original, zipped, file. If you want to keep the original, use the -k option.
Once you have the dumpname.sql file available, you can read it into the database with the newly created user using the source command as shown below.
@srisharan_v_s:matrix.orgmysql -u username -p
enter the password here
mysql> USE databasename;
mysql> SOURCE dumpname.sql;
mysql> EXITNow you should have a new database with the old database contents on the new server, with an associated database user. For WordPress sites, make sure that you reflect any changes in the associated wp-config.php file.
The other piece of the puzzle that was new to me was to run WordPress from a subdirectory, e.g. example.com/blog/, rather than from the root level, e.g. example.com/.
Removing most of the nginx server configuration, the following parts does the magic:
server {
root /var/www/thelins.se;
index index.php index.html;
server_name thelins.se www.thelins.se;
...
# For root
location / {
try_files $uri $uri/ /index.php?$args;
}
# For subdirectory
location /johan/blog/ {
try_files $uri $uri/ /johan/blog/index.php?$args;
}
location ~ \.php$ {
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass unix:/run/php/php7.4-fpm.sock;
fastcgi_index index.php;
include fastcgi.conf;
}
...
}The trick was to ensure that the subdirectory try_files statement refer to the correct index.php. Notice that this has to be done for each WordPress instance, if you happen to have multiple WordPress installations in various subdirectories on the same domain.
Its a bit of hassle to migrate a lot of web sites at once, but the monetary saving from moving the low traffic sites onto a single VPS, and the simplification of the management and monitoring by moving all VPSes to a single provider makes it worth it.
The last maintenance release of the 24.12 cycle is out.
For the full changelog continue reading on kdenlive.org.
In the previous blog, you learned all about moving items within a single view, to reorder them.
In part 2, we are still talking about moving items, and still about inserting them between existing items (never overwriting items) but this time the user can move items from one view to another. A typical use case is a list of available items on the left, and a list of selected items on the right (one concrete example would be to let the user customize which buttons should appear in a toolbar). This also often includes reordering items in the right-side list, the good news being that this comes for free (no extra code needed).
Moving a row between treeviews, step 1
Moving a row between treeviews, step 2
Moving a row between treeviews, step 3
Example code for flat models and example code for tree models.
To allow dragging items out of the view, make sure to do the following:
☑ Call view->setDragDropMode(QAbstractItemView::DragOnly) (or DragDrop if it should support both).
☑ Call view->setDragDropOverwriteMode(false) so that QTableView calls removeRows when moving rows, rather than just clearing their cells
☑ Call view->setDefaultDropAction(Qt::MoveAction) so it's a move and not a copy
To implement dragging items out of a model, you need to implement the following:
class CountryModel : public QAbstractTableModel
{
~~~
Qt::ItemFlags flags(const QModelIndex &index) const override
{
if (!index.isValid())
return {}; // depending on whether you want drops as well (next section)
return Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsDragEnabled;
}
// the default is "return supportedDropActions()", let's be explicit
Qt::DropActions supportedDragActions() const override { return Qt::MoveAction; }
QMimeData *mimeData(const QModelIndexList &indexes) const override; // see below
bool removeRows(int position, int rows, const QModelIndex &parent) override; // see below
};More precisely, the check-list is the following:
☑ Reimplement flags() to add Qt::ItemIsDragEnabled in the case of a valid index
☑ Reimplement supportedDragActions() to return Qt::MoveAction
☑ Reimplement mimeData() to serialize the complete data for the dragged items. If the views are always in the same process, you can get away with serializing only node pointers (if you have that, e.g. for tree models) and application PID (to refuse dropping onto another process). Otherwise you can encode the actual data, like this:
QMimeData *CountryModel::mimeData(const QModelIndexList &indexes) const
{
QByteArray encodedData;
QDataStream stream(&encodedData, QIODevice::WriteOnly);
for (const QModelIndex &index : indexes) {
// This calls operator<<(QDataStream &stream, const CountryData &countryData), which you must implement
stream << m_data.at(index.row());
}
QMimeData *mimeData = new QMimeData;
mimeData->setData(s_mimeType, encodedData);
return mimeData;
}s_mimeType is the name of the type of data (make up a name, it usually starts with application/x-)
☑ Reimplement removeRows(), it will be called after a successful drop. For instance, if your data is in a vector called m_data, the implementation would look like this:
bool CountryModel::removeRows(int position, int rows, const QModelIndex &parent)
{
beginRemoveRows(parent, position, position + rows - 1);
for (int row = 0; row < rows; ++row)
m_data.removeAt(position);
endRemoveRows();
return true;
}☑ Call view->setDragDropMode(QAbstractItemView::DragDrop) (already done if both views should support dragging and dropping)
To implement dropping items into a model (between existing items), you need to implement the following:
class DropModel : public QAbstractTableModel
{
~~~
Qt::ItemFlags flags(const QModelIndex &index) const override
{
if (!index.isValid())
return Qt::ItemIsDropEnabled;
return Qt::ItemIsEnabled | Qt::ItemIsSelectable; // and optionally Qt::ItemIsDragEnabled (previous section)
}
// the default is "copy only", change it
Qt::DropActions supportedDropActions() const override { return Qt::MoveAction; }
QStringList mimeTypes() const override { return {QString::fromLatin1(s_mimeType)}; }
bool dropMimeData(const QMimeData *mimeData, Qt::DropAction action,
int row, int column, const QModelIndex &parent) override; // see below
};☑ Reimplement supportedDropActions() to return Qt::MoveAction
☑ Reimplement flags()
For a valid index, make sure Qt::ItemIsDropEnabled is NOT set (except for tree models where we need to drop onto items in order to insert a first child).
For the invalid index, add Qt::ItemIsDropEnabled, to allow dropping between items.
☑ Reimplement mimeTypes() and return the name of the MIME type used by the mimeData() function on the drag side.
☑ Reimplement dropMimeData()
to deserialize the data and insert new rows.
In the special case of in-process tree models, clone the dragged nodes.
In both cases, once you're done, return true, so that the drag side then deletes the dragged rows by calling removeRows() on its model.
bool DropModel::dropMimeData(const QMimeData *mimeData, Qt::DropAction action, int row, int column, const QModelIndex &parent)
{
~~~ // safety checks, see full example code
if (row == -1) // drop into empty area = append
row = rowCount(parent);
// decode data
const QByteArray encodedData = mimeData->data(s_mimeType);
QDataStream stream(encodedData);
QVector<CountryData> newCountries;
while (!stream.atEnd()) {
CountryData countryData;
stream >> countryData;
newCountries.append(countryData);
}
// insert new countries
beginInsertRows(parent, row, row + newCountries.count() - 1);
for (const CountryData &countryData : newCountries)
m_data.insert(row++, countryData);
endInsertRows();
return true; // let the view handle deletion on the source side by calling removeRows there
}Example code can be found following this link.
On the "drag" side:
☑ Call widget->setDragDropMode(QAbstractItemView::DragOnly) or DragDrop if it should support both
☑ Call widget->setDefaultDropAction(Qt::MoveAction) so the drag starts as a move right away
On the "drop" side:
☑ Call widget->setDragDropMode(QAbstractItemView::DropOnly) or DragDrop if it should support both
☑ Reimplement supportedDropActions() to return only Qt::MoveAction
When using QTableWidget, in addition to the common steps above you need to:
On the "drag" side:
☑ Call item->setFlags(item->flags() & ~Qt::ItemIsDropEnabled); for each item, to disable dropping onto items.
☑ Call widget->setDragDropOverwriteMode(false) so that after a move the rows are removed rather than cleared
On the "drop" side:
☑ Call widget->setDragDropOverwriteMode(false) so that it inserts rows instead of replacing cells (the default is false for the other views anyway)
☑ Another problem is that the items created by a drop will automatically get the Qt::ItemIsDropEnabled flag, which you don't want. To solve this, use widget->setItemPrototype() with an item that has the right flags (see the example).
When using QTreeWidget, you cannot disable dropping onto items (which creates a child of the item).
You could call item->setFlags(item->flags() & ~Qt::ItemIsDropEnabled); on your own items, but when QTreeWidget creates new items upon a drop, you cannot prevent them from having the flag Qt::ItemIsDropEnabled set. The prototype solution used above for QTableWidget doesn't exist for QTreeWidget.
This means, if you want to let the user build and reorganize an actual tree, you can use QTreeWidget. But if you just want a flat multi-column list, then you should use QTreeView (see previous section on model/view separation).
If the user should be able to choose between copying and moving items, follow the previous section and make the following changes.
On the "drag" side:
☑ Call view->setDefaultDropAction(...) to choose whether the default should be move or copy. The user can press Shift to force a move, and Ctrl to force a copy.
☑ Reimplement supportedDragActions() in the model to return Qt::MoveAction | Qt::CopyAction
On the "drop" side:
☑ Reimplement supportedDropActions() in the model to return Qt::MoveAction | Qt::CopyAction
The good news is that there's nothing else to do.
On the "drag" side:
☑ Call widget->setDefaultDropAction(...) to choose whether the default should be move or copy. The user can press Shift to force a move, and Ctrl to force a copy.
Until Qt 6.10 there was no setSupportedDragActions() method in the item widget classes (that was QTBUG-87465, I implemented it for 6.10). Fortunately the default behavior is to use what supportedDropActions() returns so if you just want move and copy in both, reimplementing supportedDropActions() is enough.
On the "drop" side:
☑ Reimplement supportedDropActions() in the item widget class to return Qt::MoveAction | Qt::CopyAction
The good news is that there's nothing else to do.
While writing and testing these code examples, I improved the following things in Qt:
In the next blog post of this series, you will learn how to move (or copy) onto existing items, rather than between them.
The post Model/View Drag and Drop in Qt - Part 2 appeared first on KDAB.
Back this month with another update on the progress for our new design system in Plasma.
This update includes:
– Icon selection and request to submit bugs
– Icon review and changes
– Plasma Sprint updates
If you would like to participate in an open design project like ours, learn more about it here: https://community.kde.org/Get_Involve… Learn more about our organization:
• Facebook: KDE Community
• Twitter: @kdecommunity
• Mastodon: @kde@floss.social
• LinkedIn: KDE • Reddit: r/kde
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#FigmaIcons #IconDesign #FigmaTutorial #LearnFigma #FigmaTips #UIUXDesign #GraphicDesign #VectorArt #FigmaDesign #IconCreation #FigmaForBeginners #FigmaWorkflow #DigitalDesign #FigmaCommunity #FigmaIconDesign #DesignWithFigma #UXDesignTips #FigmaTipsAndTricks #IllustrationDesign #IconDesignTutorial #penpot #opensource #opendesign
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 we will cover the past two weeks as I was traveling last weekend.
Last week we released KDE Gear 24.12.3, which concludes the 24.12 series of KDE Gear. 25.04.0 is right around the corner, with only a few days left before the beta and feature freeze. Aside from the numerous bug fixes and polishing going on, we also had some pretty big changes in Krita regarding advanced text editing options, KDevelop with support for the LSP protocol, some big UI changes in Dolphin, and a complete rewrite of systemDGenie.
Balló György added improvements to many Kirigami projects for when they run with the software rendering backend. Projects that have been improved include Kirigami and Kirigami Addons, but also many apps like Tokodon, Kaidan, Angelfish and more.
Volker wrote a small report about the recent improvements to KDE Apps on Android. You can find it on his blog.
We fixed an issue in KIO SFTP support where symlinks would be truncated (Kishore Gopalakrishnan, 25.04.0. Link), and another in KIO SMB support where shared resources from other computers on multiple LANs and virtual LANs were not displayed when using WSDD (Harald Sitter, 24.12.3. Link).
Another thing that got fixed was an issue where the report bug button would not open the report URL (Carl Schwan, KF 1.12.0. Link).
Balló György fixed restoring the hidden Elisa instance on file opening (Balló György, 25.04.0. Link), and Jack Hill fixed the spacebar play/pause action, as it was not being triggered when specific buttons had the focus (Jack Hill, 25.04.0. Link).
Pedro Hernández added an option to display hidden files (Pedro Hernandez, 25.04.0. Link), and we changed how image size integers were displayed to make them clearer in all languages. Previously, we displayed 1,024x1,024. Now it is 1024x1024.
Bart De Vries properly implemented single instance behavior (Bart De Vries, 25.04.0. Link).
Okular now supports, in addition to S/MIME based signatures, PGP/GPG based signatures. PGP signatures have the advantages that it is a lot easier to get a PGP key than a S/MIME key. Note that this feature is not yet enabled by default and for the moment only works between Okular users (Sune Vuorela, 25.04.0. Link).
Darby Johnston added support for OpenTimelineIO export and import using the C++ library. This allows importing and exporting projects files to/from other video-editing applications that implement this open standard (Darby Johnston supported by KDenlive fundraiser, 25.04.0. Link).
Wolthera van Hövell implemented basic support for the font-feature-settings CSS property in Krita. This allows tweaking the rendering of text based on OpenType font features (Wolthera van Hövell, Link). Wolthera wrote an excellent blog post on this topic, as well as covering the support of font variants mentioned two weeks ago. You can find the post on her blog.
Maciej Jesionowski added a global pen tilt direction offset, which can be helpful to make the brushes feel the same for right- and left-handed users (Maciej Jesionowski, Link).
The process of porting Krita to Qt6 is making good progress: the macOS version now compiles (Freya Lupen. Link), and the implementation of the tablet switching API for Windows is now using Qt APIs instead of a custom implementation (Dmitry Kazakov, Link).
In other news, Carl Schwan fixed the menubar visibility state being saved as non visible if the global menu option is turned on. This become an issue when turning off the global menu, as Krita's menubar wouldn't appear again (Carl Schwan, Link).
Allen Winter improved the agent selection dialog. Now the Ok button is only enabled when an item is selected and the search text field has a placeholder (Allen Winter, 25.04.0. Link).
Shubham Shinde added support for displaying holidays in the week view and the month view. Note that it is possible to disable this feature (Shubham Shinde, 25.04.0. Link 1, link 2 and link 3).
Tobias Fella fixed decrypting files with very long paths on Windows (Tobias Fella, 25.04.0. Link).
Milian Wolff optimized some code in Qt related to timezones to improve the performance of some serialization in Akonadi. (Milian Wolff, Qt 6.8. Link)
Volker Krause unified the formatting of temperature ranges and dynamic depending on the home country. Similarly, imperial speed units are shown for countries that use them (Volker Krause, 25.04.0. Link 1 and link 2).
Again Itinerary has increased the number of ticket types it supports and now handles multi-page 12go PDF tickets and Ghotel reservation emails.
Joshua Goins moved the "Explore rooms" button from the hamburger to the space drawer (Joshua Goins, 25.04.0. Link), added a dialog explaining what to do next when tapping "Verify this device" (Joshua Goins, 25.04.0. Link), and made joining remote rooms more reliable (Joshua Goins, 25.04.0. Link). Joshua also fixed a bug where emoji autocompletion would destroy the current message draft (Joshua Goins, 25.04.0. Link).
Meanwhile, James Graham improved the handling of switching link previews on and off (James Graham, 25.04.0. Link).
Niels Thykier added built-in support for the debputy language server. This is used when writing Debian package (Niels Thykier, 25.04.0. Link).
Meanwhile, Joshua Goins improved the titles of terminal tabs and assigning an icon to them (Joshua Goins, 25.04.0. Link). Joshua also improved the UI of the compiler explorer integration. This includes polishing some strings, adding tooltips and fixing some padding issues (Joshua Goins, 25.04.0. Link).
KDevelop now support the Language Server Protocol (LSP) in addition to the native support for C++, PHP and Python. This reuses Kate's plugin, so, at the moment, it is only available when Kate is also installed (Igor Kushnir and Sven Brauch, 25.04.0. Link).
Jonathan Marten fixed a crash when double clicking on a terminal scroll bar (Jonathan Marten, 25.04.0. Link).
Natsumi Higa fixed the extraction of timestamps from 7-Zip archives, which now includes nanoseconds (Natsumi Higa, 25.04.0. Link).
Dolphin is having its looks tweaked and has a new icon with an actual picture of a dolphin inside it! (Darshan Phaldesai, 25.04.0. Link).
In the same vein, Akseli Lahtinen added a background to the navigation bar of Dolphin and Gwenview (Akseli Lahtinen, KF 6.12.0. Link).
And Nate Graham added a nicer split icon to the toolbar (Nate Graham, 25.04.0. Link).
In other Dolphin news, Akseli Lahtinen fixed a crash when opening a new tab with search (Akseli Lahtinen, 24.12.3. Link).
systemDGenie was completely rewritten using QML. The new version also relies a lot less on blocking DBus calls (Carl Schwan, 1.0.0. Link).
Xuetian Weng sorted a security issue and passwords copied from the KWallet Manager are no longer visible in the clipboard history of Plasma (Xuetian Weng, 25.04.0. Link).
Balló György fixed the font size of the result view. The font size was stored as point size, but passed as pixel size, causing that the actual font size is smaller than it should be (Balló György, 25.04.0. Link). Balló also fixed the background color of some views when switching to a dark theme (Balló György, 25.04.0. Link).
Max Brazhnikov Added support for non-latin alphabets (Max Brazhnikov, 25.04.0. Link).
Hy Murveit added an altitude graph to the scheduler table (Hy Murveit, Link)
Mark Penner made the text elide in the RSS entry list so that the buttons are always visible (Mark Penner, 25.04.0. Link), and Balló György set the default format to import and export feeds as OPML (Balló György, 25.04.0. Link).
José Rebelo added the possibility of filtering out notifications from the Android work profile (José Rebelo, Link).
Kai Uwe Broulik added an option to explore in Filelight (Kai Uwe Broulik, 25.12.0. Link), and icons to the context menu entries (Kai Uwe Broulik, 25.12.0. Link).
Balló György fixed the windows activation when the current window is in the system tray (Balló György, 25.04.0. Link).
Fabio Bas added a setting for desktop scale and device scale (Fabio Bas, 25.04.0. Link), while Fabian Lesniakd disabled Kerberos support completely, since it turned out that having a broken support for it was worse than no support at all (Fabian Lesniak, 25.04.0. Link).
Balló György fixed the name of the generated optimized images, and now the suffix is appended before the file extension (Balló György, Link).
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.
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.
Make sure you commit anything you want to end up in the KDE Gear 25.04
releases to them
Next Dates
March 13 2025: 25.04 Freeze and Beta (25.03.80) tag & release
March 27, 2025: 25.04 RC (25.03.90) Tagging and Release
April 10, 2025: 25.04 Tagging
April 17, 2025: 25.04 Release
https://community.kde.org/Schedules/KDE_Gear_25.04_Schedule
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.
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.
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.
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.
Now, setting up the glyph model can get quite slow, so some trade-offs were established:
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…
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…
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.
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.
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