Planet KDE

Make sure you commit anything you want to end up in the KDE Gear 24.12
releases to them

Next Dates:

•   November 14, 2024: 24.12 freeze and beta (24.11.80) tagging and release
•   November 28, 2024: 24.12 RC (24.11.90) tagging and release
•   December  5, 2024: 24.12 tagging
•   December 12, 2024: 24.12 release

https://community.kde.org/Schedules/KDE_Gear_24.12_Schedule

Let’s go for my web review for the week 2024-45.

Voted in America? This Site Doxed You

Tags: tech, democracy

I didn’t know the voting rolls were public record in the US… this is a really bad idea.

https://www.404media.co/voted-in-america-this-site-doxed-you/

One weird trick to get the whole planet to send abuse complaints to your best friend(s)

Tags: tech, networking, security, protocols

Looks like there are people out there to get Tor relays down… and they found a smart networking trick I’d expect to not work anymore.

https://delroth.net/posts/spoofed-mass-scan-abuse/

XMPP: the forgotten gem of Instant Messaging

Tags: tech, xmpp, ux

Could XMPP make a come back if the user experience was better?

https://adele.pages.casa/md/blog/xmpp-the-forgotten-gem-of-instant-messaging.md

A conceptual model of ATProto and ActivityPub

Tags: tech, protocols, fediverse, governance, decentralized

Interesting explanation of the different visions and governance behind ActivityPub and ATProto.

https://fediversereport.com/a-conceptual-model-of-atproto-and-activitypub/

A Map of Sync

Tags: tech, syncing, data

Interesting dimensions to use when classifying syncing solutions and to see which ones will meet your constraints.

https://stack.convex.dev/a-map-of-sync

DuckDB over Pandas/Polars

Tags: tech, databases, data-science

A good reminder that I should probably evaluate DuckDB for some of my tooling.

https://pgrs.net/2024/11/01/duckdb-over-pandas-polars/

Why systemd is a problem for embedded Linux

Tags: tech, systemd, embedded

This is a good point. systemd is kind of turning into a monoculture, but what are we loosing? Indeed, right now things could be better on deeply embedded systems (I insist on the “deep embedded” here which is often more limited in resources). Unlike the author I think they could be improved and they don’t quite apply to a good chunk of recent embedded platforms though.

https://kevinboone.me/systemd_embedded.html

How the New sqlite3_rsync Utility Works

Tags: tech, databases, sqlite, tools, syncing

If you wonder how the protocol is designed and how the actual implementation works, this is a nice introduction. Clearly it’s helped by the size of that program which is fairly small.

https://nochlin.com/blog/how-the-new-sqlite3_rsync-utility-works

C++, Complexity, and Compiler Bugs

Tags: tech, c++, complexity

Good illustration of how the C++ language complexity is out of hands.

https://azeemba.com/posts/cpp-complexity-compiler-bugs.html

Having fun with modern C++ – Daniel Lemire’s blog

Tags: tech, c++

Still, C++ improved in recent years. The problem is that we tend to stick too much to the old constructs we already know and that things keep piling up but nothing is removed.

https://lemire.me/blog/2024/11/02/having-fun-with-modern-c/

smolweb HTML specification

Tags: tech, html, accessibility, low-tech, complexity

A nice subset of HTML to ensure better accessibility and reduced complexity.

https://smolweb.org/specs/index.html

HTML link, or button, that is the question

Tags: tech, web, frontend, html

Each has a use, they shouldn’t be conflated. It makes for poor user experience and accessibility otherwise.

https://marijkeluttekes.dev/blog/articles/2024/11/04/html-link-or-button-that-is-the-question/

Long Distance Relationships

Tags: tech, remote-working, management, product-management

A bit biased toward stable product teams only. Still, there are good tips which are more widely applicable here. This gives a good idea of the management of a distributed team of remote workers.

https://matt.blwt.io/post/long-distance-relationships/

Bye for now!

I spent past three weeks working on refactoring and fixing legacy code (the oldest of which was from 2013) that handled positioning Plasma desktop icons, and how this data was saved and loaded.

Here's the merge request if you're curious: plasma-desktop: Refactor icon positioner saving and loading

The existing code worked sometimes, but there were some oddities like race conditions (icon positioning happens in weird order) and backend code mixed in with frontend code.

Now I am not blaming anyone for this. Code has tendency to get a bit weird, especially over long periods of time, and especially in open source projects where anyone can tinker with it.

You know how wired earbuds always, always get tangled when you place them in a drawer or your pocket or something for few seconds? Codebases do the exact same thing, when there are multiple people writing on things, fixing each others' bugs. Everyone has a different way of thinking, so it's only natural that things over time get a bit tangled up.

So sometimes you need someone to look at the tangled codebase and try to clear it up a bit.

Reading code is the hardest part

When going through old code, especially some that has barely any comments, it can take a very long time to understand what is actually going on. I honestly spent most of my time trying to understand how the thing even works, what is called when, where the icons positions are updated, and so on.

When I finally had some understanding of what was happening, I could start cleaning things up. I renamed a lot of the old methods to be hopefully more descriptive, and moved backend code — like saving icon positions — from the frontend back to backend.

Screens and icons

Every screen (PC monitor, TV…) tends to have it's own quirks. Some, when connected with display-port adapter, tell your PC it's disconnected if your PC goes to screen saving mode. Some stay connected, but show a blank screen.

One big issue with the icon positions was that when screen got turned off, it thought there was no screen anymore and started removing items from the desktop.

That's fair. Why show desktop icons on a screen that is non-existent? But when you have a monitor that tells your PC, "Okay I'm disconnecting now!" when the PC says it's time to sleep, wrong things would happen.

This condition is now handled by having a check that if the screen is in use or not. Now when screen is not in use, we just do nothing with the icons. No need to touch them at all.

Stripes and screen resolution

Our icon positioning algorithm uses something called "stripes."

Every resolution has it's amount of stripes. Stripes contain an array of icons, or blank spots.

So if your screen resolution is, let's say, 1920x1080, we calculate how many stripes and how many items per stripe will fit on that screen.

Stripe1: 1 2 3 4 5 6 7 Stripe2: 1 2 3 4 5 6 7 Stripe3: 1 2 3 4 5 6 7 And so on..

But when you change your screen resolution or scale factor, how many icon stripes you have and how many icons fit on each stripe will change.

So if you have one of those screens that looks to the system like it's been unplugged when it goes into sleep mode, previously the stripe amount would change to 1 row, 1 column. And the icon positioner would panics and shove all icons in that 1,1 slot.

Then when you'd turn the screen back on, the icon positioner would wonder what just happened and restore the proper stripe number and size. But by that point it would have lost all our positioning coordinate data during the shoving of icons in that one miniscule place, so instead it would reset the icon positions… and this leaves users wondering why their desktop icon arrangement is now gone.

Here we have to also check for the screen being in use or not. But there were other problems.

Saving icon positions

The prior code saved the icon positions every time the positions changed. Makes sense.

But it didn't account for the screen being off… so the icon positions would get saved while the desktop was in a faulty state. This also causes frustration because someone arranges the icons how they wish, but then screen does something weird and they're now saved in wrong places again.

Our icon positions were updated after almost every draw call, if the positions changed. So this would mean the saving would happen rather often and no matter what moved them.

We had to separate the user action from computer action. If computer moves the icons, we ideally do not save their positions, unless something drastic has happened like resolution change.

The icon positions are saved per resolution, so if you move icons around while they're displayed on a 3440x1440 screen and then change the resolution to 1920x1080, both will have their own arrangements. This part of the codebase did not previously work, and it would always override the old configuration, which caused headache.

So now we only save icon positions when:

• The user adds or removes a desktop icon
• The user moves a desktop icon
• The user changes the desktop resolution

This makes the icon position saving much less random, since it's done only after explicit user actions.

Margin errors

The last thing that caused headaches with the icon positioning was that the area available on the desktop for icons was determined before panels were loaded. When the panels loaded, they would reduce the amount of space for desktop icons, and that area would constantly resize until everything is ready.

In previous code, this would cause icons to move, which updates positions, which then saves their positions.

So let's say you arrange your icons nicely, but the next time you boot into plasma, your panels start shoving the poor icon area around and the icons have to move out of the way… and now they're all in the wrong places.

This was already partially fixed by not saving when the computer moves the icons around: we just load the icon positions when the screen is in use and we are done with listing the icons on the desktop. Part of the margin changes happen when screen is off.

We still need to fix the loading part; ideally we load the icon area last, so that it gets the margins it expects and doesn't shuffle around while panels are still appearing. But it was out of scope for this merge request.

Conclusions

It may not sound like much, but this was a lot of work. I spent days just thinking about this problem, trying to understand what is happening now and how to improve it.

Luckily with a lot of help from reviewers and testers I got things to work much better than it used to. I am quite "all-over-the-place" when I solve problems so I appreciate the patience they had with me and my questions. :D

What I mostly wished for when working on this were more inline code comments. You don't need to comment the obvious things, but everything else could use something. It's hard to gauge what is obvious and what is not, but that kind of answers the question: If you don't know if it's obvious or not, it's likely not, so add some comment about it.

I do hope that the desktop icons act more reliably after all these changes. If you spot bugs, do report them at https://bugs.kde.org.

Thanks for reading! :)

PS. The funniest thing to me about all of this is that I do not like having any icons on my desktop. :'D

Friday, 8 November 2024

KDE today announces the release of KDE Frameworks 6.8.0.

KDE Frameworks are 72 addon libraries to Qt which provide a wide variety of commonly needed functionality in mature, peer reviewed and well tested libraries with friendly licensing terms. For an introduction see the KDE Frameworks release announcement.

This release is part of a series of planned monthly releases making improvements available to developers in a quick and predictable manner.

New in this version Baloo

• [excludeMimeTypes] Exclude model/obj and text/rust from content indexing. Commit. See bug #488533

Bluez Qt

• Simplify PendingCallPrivate. Commit.

Breeze Icons

• Add mimetype icons for text/x-typst. Commit.
• Monochromize not-explicitly-colorized symbolic folder icons. Commit. Fixes bug #494721
• Add CI for static builds on Linux. Commit.
• Unify common parts of index.theme for breeze and breeze-dark. Commit.
• Sync index.theme changes from breeze to breeze-dark. Commit. Fixes bug #494399
• Rename spinbox-* icons to value-*. Commit.

Extra CMake Modules

• FindKF6: Print custom message when required components are not found. Commit.
• Add a directory check when appending a module dir to qmlimportscanner. Commit.
• Add Python bindings. Commit.
• Break enums onto multiple lines. Commit.
• Set import paths for QML modules to all CMake search paths. Commit.
• Remove the old/unused SIP-based Python binding generation infrastructure. Commit.
• ECMGeneratePkgConfigFile: try to deduce additional include dirs. Commit.
• Fix custom definitions for generated pkgconfig files. Commit.
• Fix QM loader unit tests with a static Qt. Commit.
• Don't fall back to qmlplugin dump on static Qt builds. Commit.
• Retire Qt5 Android CI. Commit.
• Automatically install dependent targets of QML modules in static builds. Commit.
• Allow to specify an export set for targets installed by finalize_qml_module. Commit.
• Don't check websites in Appstream tests. Commit.

KArchive

• Add CI for static builds on Linux. Commit.
• [k7zip] Correctly handle pack sizes > INT_MAX. Commit.

KBookmarks

• Port to KStandardActions. Commit.
• Add missing include. Commit.

KCalendarCore

• Fix Duration's operator- accidentally adding instead of subtracting. Commit.
• Add CI for static builds on Linux. Commit.

KCMUtils

• Fix compilation with Qt 6.9 (dev). Commit.

KCodecs

• Add test for passing unknown codec to codecForName. Commit.
• Fix buffer overflow in Codec::codecForName. Commit.

KColorScheme

• Reset palette to default-constructed one when scheme is unset. Commit.
• Don't call activateSchemeInternal in init unless really needed. Commit.
• Add CI for static builds on Linux. Commit.

KCompletion

• Add linux-qt6-static CI. Commit.

KConfig

• Kwindowconfig: If sizes are same as default, revert them to default when saving. Commit. See bug #494377
• Add CI for static builds on Linux. Commit.
• Correctly install QML module in a static build. Commit.

KConfigWidgets

• Add CI for static builds on Linux. Commit.

KContacts

• Fix IM protocol resource data initialization in static builds. Commit.

KCoreAddons

• Make KJob::elapsedTime const. Commit.
• Fix absolute path generation into (not installed) header. Commit.
• KPluginMetaData: reduce string allocation. Commit.
• Update git blame ignore file. Commit.
• Reformat code with clang-format. Commit.
• Kjob: add elapsedTime() returns the ms the job ran. Commit.
• Add CI for static builds on Linux. Commit.
• Install QML module correctly when building statically. Commit.
• ExportUrlsToPortal: use QScopeGuard::dismiss for the success code path. Commit.

KDocTools

• Upload new file sq.xml. Commit.

KFileMetaData

• UserMetadata: complete Windows implementation. Commit.

KGlobalAccel

• Add WITH_X11 option to re-enable X11 code after runtime cleanup. Commit.
• Add CI for static builds on Linux. Commit.

KGuiAddons

• Add namespace for Android as required by newer gradle versions. Commit.
• Add CI for static builds on Linux. Commit.
• Correctly install static QML modules. Commit.

KHolidays

• Fix misunderstanding of All Saints Day in Swedish calendar. Commit.
• Add CI for static builds on Linux. Commit.

KI18n

• Allow explicit setting of Python3 fallback executible path. Commit.
• Use raw pointer for some pimpl'd public classes. Commit.
• Add missing include. Commit.
• Trigger binding reevaluation on language change. Commit.
• Propagate QML dependency for a static build with KTranscript enabled. Commit.
• Add CI for static builds on Linux. Commit.
• Reduce temporary allocations. Commit.
• Modernize member initialization. Commit.
• Fix container size type narrowing warnings. Commit.
• Remove commented-out KLocale leftovers. Commit.
• Align argument names between definition and declaration. Commit.
• Re-evaluate the languages we translate to on QEvent::LanguageChange. Commit.
• Cleanup KLocalizedContext d-ptr handling. Commit.
• Special-case the language fallback for country-less English. Commit.
• Use QStringView for locale splitting. Commit.

KIconThemes

• Port to KStandardActions. Commit.
• Postpone spawning KColorSchemeManager instance. Commit.
• Add CI for static builds on Linux. Commit.
• Init mimeType icons on demand. Commit.
• Set up KColorSchemeManager on Android as well. Commit.
• Reduce temporary allocations. Commit.

KImageformats

• TGA: Fixed GrayA image loading error. Commit.
• Exr: Fix read/write with openexr 3.3. Commit. Fixes bug #494571
• JXL improvements. Commit.
• JXR: Fixed image reading on sequential devices. Commit.
• Simplified read/verify header process. Commit.

KIO

• Minor: use existing variables which contain these strings. Commit.
• Fix crash from HTTPProtocol::del() which calls with inputData=nullptr. Commit.
• Port away from Qt::Core5Compat when using Qt 6.7 or newer. Commit.
• Remove unused KConfigWidgets dependency. Commit.
• Port to KStandardActions. Commit.
• Add missing KColorScheme link. Commit.
• Add missing include. Commit.
• Include DBus error in log when communication with kpasswdserver fails. Commit.
• Update git blame ignore file. Commit.
• Reformat code with clang-format. Commit.
• Copyjob/transferjob: use KJob::startElapsedTimer. Commit.
• Http worker: handle dav[s] protocol. Commit. Fixes bug #365356
• [KFileFilterCombo] Fix setting 'All' filter as default. Commit.
• KNewFileMenu: Prevent using home directory as template directory. Commit. Fixes bug #494679
• [KFileFilter] Ignore label when comparing filters. Commit.
• [KFileFilter] Remove excess spaces in logging. Commit.
• [KFileFilterCombo] More verbose logging when not finding a filter. Commit.
• [http] Inline handleRedirection into the metaDataChanged slot. Commit.
• [webdav] Handle redirections which add trailing slashes. Commit. See bug #484580
• Copyjob: prefer custom struct over std::pair. Commit.
• PreviewJob: use standard thumbnailer caching is disabled. Commit.
• KDirListerTest: improve test stability. Commit.
• Tests: Make sure KIO::UDSEntryList can be compared. Commit.
• Expose UDSEntry equal operator to KIO namespace. Commit.
• Core/copyjob: report speed when copying multiple files. Commit. See bug #391199
• KPreview: store standard thumbnails in /tmp subfolder. Commit.
• Preview: better clean after standard thumbnailer. Commit. Fixes bug #493274
• Openurljob.cpp: Avoid opening files in endless loop if mimetype is set to open with xdg-open. Commit. Fixes bug #494335
• [KFilePlacesView] Improve automatic resize heuristic. Commit. Fixes bug #449544
• Workerinterface: remove unused #include. Commit.
• Add translation context to admin security warning. Commit.
• Kfileitem: linkDest prevent readlink error when file is not a symlink. Commit.
• Check that admin worker was installed by root. Commit.
• Clean up Properties dialog to follow HIG, improve UX, remove frames and fix padding regression. Commit. Fixes bug #484789
• TrashSizeCache: Use correct flags for QDirIterator. Commit. See bug #479283

Kirigami

• TitleSubtitle: Don't explicit set renderType. Commit.
• Upper mound for overlaysheet width. Commit.
• SelectableLabel: fix a11y properties. Commit.
• Fix Kirigami Application (Qt6) template. Commit. Fixes bug #494478
• SelectableLabel: Use onPressedChanged. Commit. See bug #481293
• Reformat code with clang-format. Commit.
• Icon: Always respect the animated property. Commit. Fixes bug #466357
• Adjust tst_qicon for desktop theme. Commit.
• Fix loading desktop theme. Commit. Fixes bug #491294
• Fix presumable typos confusing background and foreground colors. Commit. See bug #491294
• Always print Theme file loading errors. Commit. See bug #491294
• SelectableLabel: override default padding values more completely. Commit. Fixes bug #495256
• Fix icon for positive state of InlineMessage. Commit.
• SelectableLabel: fix binding loop warning on cursorShape. Commit.
• ScrollablePage: Add properties to set if the scrollbars are interactive. Commit.
• SelectableLabel: use property alias instead of direct binding, expose more through aliases. Commit.
• Dialog: fix multiple binding loops (again). Commit.
• Make the close button actually close. Commit.
• Layout: Reverse the stacking order of items inserted into ToolBarLayout. Commit. See bug #490929
• Modify SelectableLabel to use TextEdit instead. Commit. See bug #493581
• Cleanup and fix static QML module installation. Commit.
• Disable PageRow gesture on android. Commit.
• Make OverlaySheet look exactly like Dialog. Commit. Fixes bug #489357
• Top align icon in multiline InlineMessage. Commit.

KItemModels

• Install QML module correctly when building statically. Commit.
• Fix QML unit tests when building against a static Qt. Commit.
• Make unit tests independent of QtWidgets. Commit.
• Don't hardcode library type. Commit.
• Kbihash: adapt to source incompatible change in Qt. Commit.

KJobWidgets

• Hide arrowButton in KWidgetJobTracker on startup. Commit.
• Add dedicated WITH_X11 option to avoid automagic. Commit.

KNewStuff

• Make sure the action's dialog closes. Commit. Fixes bug #492998
• Put qnetworkreplys in a self-aborting unique_ptr. Commit. See bug #492998
• Parent the xml loader's httpjob. Commit. See bug #492998
• Filecopyworker: try to gracefully quit the thread. then terminate it. Commit. See bug #492998

KNotifications

• Typo--. Commit.
• Add namespace for Android as required by newer gradle. Commit.
• Add CI for static builds on Linux. Commit.

KParts

• Define undeprecated Capabilities key in JSON metadata, define JSON schema, remove obsolete key. Commit.

KQuickCharts

• Add CI for static builds on Linux. Commit.
• Correctly install static QML modules. Commit.

KStatusNotifieritem

• Fix absolute path generation in (not installed) header. Commit.
• Typo--. Commit.

KTextEditor

• Vi mode: Don't infinite loop in searcher. Commit.
• Remove unused var. Commit.
• Fix ignores. Commit.
• Less deprecated stuff used. Commit.
• Don't temporarily clear document URL during openUrl(). Commit.
• Only discard completion if the cursor was at the end of line. Commit.
• Update git blame ignore file. Commit.
• Reformat code with clang-format. Commit.
• Fix implicit conversion of Qt::Key in Qt 6.9. Commit.
• Try to avoid unwanted completions. Commit.
• Fix session restore of file type. Commit. Fixes bug #492201
• Make ViewPrivate::displayRangeChanged public. Commit.
• Set DocumentPrivate::m_reloading to false only if loading. Commit.
• Give a more proper name to the test. Commit.
• Fix multiblock range handling when unwrapping line. Commit. Fixes bug #494826
• Fix line removal not handled properly in KateTemplateHandler. Commit. Fixes bug #434093
• Inline blocksize into buffer. Commit.
• Improve MovingRangeTest::benchCheckValidity. Commit.
• Improve TextRange::checkValidity performance. Commit.
• Do all testing in clean temp dirs. Commit.
• Add a swap file test. Commit.
• Add benchmarks for moving stuff. Commit.
• Use std::vector for cursor storage. Commit.
• Allow disabling editorconfig. Commit. Fixes bug #471008

KTextTemplate

• Import i18n scripts from grantlee. Commit. Fixes bug #492237
• Fix "now" tag to allow single quoted strings. Commit.

KTextWidgets

• Port to KStandardActions. Commit.
• Make implicit deps explicit. Commit.

KUnitConversion

• Add CI for static builds on Linux. Commit.

KWallet

• Don't exclude deprecated functions from build. Commit. Fixes bug #493356

KWidgetsAddons

• Fix time entry in locales with mixed-case AM/PM suffixes. Commit.
• Add CI for static builds on Linux. Commit.
• Don't use Oxygen style in KSeparator. Commit.
• KMessageWidget: Improve accessibility. Commit.

KXMLGUI

• Simplify code: use erase remove. Commit.
• Fix window position not being restored. Commit. Fixes bug #493401

Prison

• Add CI for static builds on Linux. Commit.

QQC2 Desktop Style

• TextArea: Make placeholder wrap. Commit.

Solid

• Restore MediaChanged handling for Audio CDs. Commit.
• Support reproducible builds by omitting host paths in bison/yacc outputs. Commit.
• [udisks] Don't add/remove devices in slotMediaChanged. Commit. See bug #464149
• Port implicit QByteArray, QChar and QString conversions in iokit. Commit.
• Drop unfinished Power API. Commit.
• Fstabwatcher: use libmount monitor on Linux. Commit.
• Fstabhandling: use libmount in Linux. Commit.

Sonnet

• Add linux-qt6-static CI. Commit.
• Remove ASPELL runtime dependency from plugin building check. Commit.
• Provide SONNET_NO_BACKENDS option to deactivate build failures with no backends. Commit.

Syndication

• Add CI for static builds on Linux. Commit.

Syntax Highlighting

• State: Fix inconsistent linkage warning on Windows. Commit.
• Better contrast for search highlighting. Commit. Fixes bug #494599
• Odin: Add escape character to strings. Commit.
• Update. Commit.
• Add comments. Commit.
• Add TLA+ syntax highlighting. Commit.
• Init. Commit.
• Move try to cflow_begin. Commit.

The last maintenance release of the 24.08 series is out.

• Fix crash caused by incorrect codec passed on opening subtitle. Commit. Fixes bug #495410.
• Fix shadowed variable causing incorrect clip removal on project opening, fix crash opening project with timeline clip missing in bin. Commit. See bug #493486.
• Fix qml crash building timeline with Qt 6.8 – ensure context property exists before setting source. Commit. See bug #495335.
• Fix generate proxy when frame size is above a value not using the current project setting. Commit.
• Fix shadow variable causing clip removal on project opening. Commit.
• Fix monitor seek to prev/next keyframe not working in rotoscoping. Commit.
• Fix missing build-in LUT files not correctly fixed on project open. Commit. See bug #494726.
• Fix clip jobs like stabilize creating invalid folders. Commit.
• Fix freeze loading project with invalid folder id. Commit.
• Don’t invalidate timeline preview when replacing an audio clip in bin. Commit.
• Ensure monitor is cleared and ruler hidden when no clip or a folder is selected in bin. Commit.

The post Kdenlive 24.08.3 released appeared first on Kdenlive.

Over 180 individual programs plus dozens of programmer libraries and feature plugins are released simultaneously as part of KDE Gear.

Today they all get new bugfix source releases with updated translations, including:

• neochat: Adjustments to make it work with the newly released libquotient 0.9 (Commit)
• kdevelop: MesonManager: remove test suites when a project is closing, (Commit, fixes bug #427157)
• kdevelop: Fix a qml crash building timeline with Qt 6.8 (Commit, fixes bug #495335)

Distro and app store packagers should update their application packages.

• 24.08 release notes for information on tarballs and known issues.
• Package download wiki page
• 24.08.3 source info page
• 24.08.3 full changelog

While I do have a Qt git build on my machine that I use for development, I usually only test individual applications and functionality but hardly ever run my full Plasma session on it. This means that for day-to-day use I typically only get to enjoy new Qt features once they have actually been released.

Proper modal dialogs under Wayland (note the darkened editor window) thanks to XDG Dialog and the new Qt 6.8

One feature I talked about in the very last issue of “On the road to Plasma 6” is a nice API for XDG Foreign. To recap: it’s a Wayland protocol that lets an application export a window to another one so it can can attach a window to it. For example, the XDG Desktop Portal wants to attach the “Open File” dialog as if it were coming from the application that requested it.

Of course we don’t want to write low-level Wayland code and instead have an easy to use API for it. The KWindowSystem::setMainWindow function does just that: hand in a window and the token you received from the other application (created through KWaylandExtras::exportWindow) and it takes care of everything else. Presumably, you want to set the parent window before showing your dialog to make absolutely sure it’s set up properly.

However, Qt did not have an API to tell us when the underlying XDG Toplevel (think: a regular desktop-y window with a title bar and what not) had been created. We were only told when the basic wl_surface was created, which was too early, or the window was exposed/shown, at which point it was already flashing up in the user’s task bar. Hence, I added a new QWaylandWindow::surfaceRoleCreated (and corresponding surfaceRoleDestroyed) signal. Utilizing that, the aforementioned KWindowSystem API now works perfectly.

Another major addition to Qt Wayland that I have been looking forward to very much is support for the XDG Dialog protocol. While a window could have always had a parent (e.g. a popup menu or settings dialog parented to the application’s main window), there was no concept of a “modal” dialog. Therefore, we did not support the “dim parent” effect under Wayland that darkens a window to indicate it cannot be interacted with. More importantly, KWin couldn’t take it into account for its focus handling either. It happily let you focus a blocked window but the application would then just ignore your input.

There’s only one Dolphin running here!

This was most noticeable for me when Alt+Tab’ing back and forth, for example using the “Open File” dialog in one application and then trying to switch to the other to verify where the file was actually located. Instead of cycling between the file dialog and the other application, it would alternate between the file dialog and the blocked main window.

Sadly, even when I upgraded to Qt 6.8 the situation didn’t improve. I noticed that Alt+Tab actually showed the dialog twice. This looked like a bug and sure enough comparing it to the Plasma 5.27 LTS session on my other computer proved that it used to work at some point. At first I didn’t spot anything obvious until I noticed a small typo that must have slipped in during some major refactoring. Instead of not including the main window when it had a modal child, it included the modal child once again! Sure enough, adding an exclamation mark (the logical NOT operator in C++) did the trick.

If you want to support more good people such as myself, consider donating to the KDE End of Year Fundraiser!

This one required a few other features to be implemented first, so let’s jump right in.

Matching reference luminances

A big part of what a desktop compositor needs to get right with HDR content is to show SDR and HDR content properly side by side. KWin 6.0 added an SDR brightness slider for that purpose, but that’s only half the equation - what about the brightness of HDR content?

When we say “HDR”, usually that refers to a colorspace with the rec.2020 primaries and the perceptual quantizer (PQ) transfer function. A transfer function describes how to calculate a real brightness value from the “electrical” signal encoded in the content - PQ specifically has encoded values from 0 to 1 and brightness values from 0 to 10000 nits. For reference, your typical office monitor does around 300 or 400 nits at maximum brightness setting, and many newer phones can go a bit above 1000 nits.

Now if we want to show HDR content on an HDR screen, the most straight forward thing to do would be to just calculate the brightness values, write them to the screen and be done with it, right? That’s what KWin did up to Plasma 6.1, but it’s far from ideal. Even if your display can show the full range of requested brightness values, you might want to adjust the brightness to match your environment - be it brighter or darker than the room the content was optimized for - and when there’s SDR things in HDR content, like subtitles in a video, that should ideally match other SDR content on the screen as well.

Luckily, there is a preexisting relationship between HDR and SDR that we can use: The reference luminance. It defines how bright SDR white is - which is why another name for it is simply “SDR white”.

As we want to keep the brightness slider working, we won’t map SDR content to the reference luminance of any HDR transfer function though, but instead we map both SDR and HDR content to the SDR brightness setting. If we have an HDR video that uses the PQ transfer function, that reference luminance is 203 nits. If your SDR brightness setting is at 406 nits, KWin will just multiply the brightness of the HDR video with a factor of 2.

This doesn’t only mean that we can make SDR and HDR content fit together nicely on HDR screens, but it also means we now know what to do when we have HDR content on an SDR screen: We map the reference luminance from the video to SDR white on the screen. That’s of course not enough to make it look nice though…

Tone mapping

Especially with HDR presented on an SDR screen, but also on many HDR screens, it will happen that the content brightness exceeds the display capabilities. To handle this, starting with Plasma 6.2, whenever the HDR metadata of the content says it’s brighter than the display can go, KWin will apply tone mapping.

Doing this tone mapping in RGB can result in changing the content quite badly though. Let’s take a look by using the most simple “tone mapping” function there is, clipping. It just limits the red, green and blue values separately to the brightness that the screen can show.

If we have a pixel with the value [2.0, 0.0, 2.0] and a maximum brightness of 1.0, that gets mapped to [1.0, 0.0, 1.0] - which is the same purple, just in darker. But if the pixel has the values [2.0, 0.0, 1.0], then that gets mapped to [1.0, 0.0, 1.0], even though the source color was significantly more red!

To fix that, KWin’s tone mapping uses ICtCp. This is a color space developed by Dolby, in which the perceived brightness (aka Intensity) is separated from the chroma components (Ct = blue-yellow, Cp = red-green), which is perfect for tone mapping. KWin’s shaders thus transform the RGB content to ICtCp, apply a brightness mapping function to only the intensity component, and then convert back to RGB.

The result of that algorithm looks like this:

RGB clipping KWin 6.2’s tone mapping MPV’s tone mapping

As you can see, there’s still some color changes going on in comparison to MPV’s algorithm; this is partially because the tone mapping curve still needs some more adjustments, and partially because we also still need to do similar mapping for colors that the screen can’t actually show. It’s already a large improvement though, and does better than the built-in tone mapping functionality in many HDR screens.

When tone mapping HDR content on SDR screens, we always end up reducing the brightness of the overall image, so that we have some brightness values to map the really bright highlights in the video to - otherwise everything just slightly over the reference luminance would look like an overexposed blob of color, as you can see in the “RGB clipping” image. There are ways around that though…

HDR on SDR laptop displays

To explain the reasoning behind this, it helps to first have a look at what even makes a display “HDR”. In many cases it’s just marketing nonsense, a label that’s put on displays to make them seem more fancy and desirable, but in others there’s an actual tangible benefit to it.

Let’s take OLED displays as an example, as it’s considered one of the display technologies where HDR really shines. When you drive an OLED at high brightness levels, it becomes quite inefficient, it draws a lot of power and generates a lot of heat. Both of these things can only be dealt with to a limited degree, so OLED displays can generally only be used with relatively low average brightness levels. They can go a lot brighter than the average in a small part of the screen though, and that’s why they benefit so much from HDR - you can show a scene that’s on average only 200 nits bright, with the sky in the image going up to 300 nits, the sun going up to 1000 nits and the ground only doing 150 nits.

Now let’s compare that to SDR laptop displays. In the case of most LCDs, you have a single backlight LED for the whole screen, and when you move the brightness slider, the power the backlight is driven at is changed. So there’s no way to make parts of the screen brighter than the rest on a hardware level… but that doesn’t mean there isn’t a way to do it in software!

When we want to show HDR content and the brightness slider is below 100%, KWin increases the backlight level to get a peak brightness that matches the relative peak brightness of that content (as far as that’s possible). At the same time it changes the colorspace description on the output to match that change: While the reference luminance stays the same, the maximum luminance of the transfer function gets increased in proportion to the increase in backlight brightness.

The results is that SDR white gets mapped to a reduced RGB value, which is at least supposed to exactly counteract the increase of brightness that we’re applying with the backlight, while HDR content that goes beyond the reference luminance gets to use the full brightness range.

Increasing the backlight power of course doesn’t come without downsides; black levels and power usage both get increased, so this is only ever active if there’s HDR content on the screen with valid HDR metadata that signals brightness levels going beyond the reference luminance.

As always, capturing HDR content with a phone camera is quite difficult, but I think you can at least sort of see the effect:

without backlight adjustment with backlight adjustment

This feature has been merged into KWin’s git master branch and will be available on all laptop displays starting with Plasma 6.3. I really recommend trying it for yourself once it reaches your distribution!

In many cases, importing data into LabPlot for further analysis and visualization is the first step in the application:

LabPlot supports many different formats (CSV, Origin, SAS, Stata, SPSS, MATLAB, SQL, JSON, binary, OpenDocument Spreadsheets (ods), Excel (xlsx), HDF5, MQTT, Binary Logging Format (BLF), FITS, NetCDF, ROOT (CERN), LTspice, Ngspice) and we plan to add support for even more formats in the future. All of these formats have their reasons for existence as well as advantages and disadvantages. However, the performance of reading the data varies greatly between the different formats and also between the different CPU generations. In this post, we’ll show how long it takes to import a given amount of data in four different formats – ASCII/CSV, Binary, HDF5, and netCDF.

This post is not about promoting any of the formats, nor is it about doing very sophisticated measurements with different amounts and types of data and extensive CPU benchmarking. Rather, it’s about what you can (roughly) expect in terms of performance on the new and not so new hardware with the current implementation in LabPlot.

For this exercise, we import the data set with 1 integer column and 5 columns of float values (Brownian motion for 5 “particles”, one integer column for the index) with 50 Millions of rows which results into 300 Millions of numerical values:

We take 6 measurements for each format, ignore the first measurement, which is almost always an outlier due to the disk cache in the kernel and results in faster file reads on subsequent accesses, and calculate the averages:

As expected, the file formats that deal with binary representation internally (Binary, HDF5, NetCDF) provide significantly better performance compared to ASCII, and this difference becomes larger the slower the CPU is. The performance of HDF5 and NetCDF is almost the same because the newer version of NetCDF is based on HDF5.

The implementation in the data import code is straightforward. Ignoring for a moment the complexity with the different options affecting the behavior of the parser, different data types and other subleties, once everything is set up it’s just a matter of iterating over the data, parsing it and converting it into the internal structures. The logic inside the loop is fixed, and a linear behavior with respect to the total number of values to read is expected. This expectation is confirmed using the same CPU (we took the fastest CPU from the table above) and varying the total number of rows with the fixed number of columns:

The performance of the import is even more critical when dealing with external data that is frequently modified. In order to provide a smooth visualization in LabPlot for such “live data”, it’s important to optimize all steps involved here, like the import of the new data itself, as well as the recalculation in the algorithms (smoothing, etc.) and in the visualization part. For the next release(s), we’re now working to further optimize the implementation to handle more performance-critical scenarios in the near future. The results of these activities, funded by the NLnet grant, will be the subject of a dedicated post soon.

Tuesday, 5 November 2024. Today KDE releases a bugfix update to KDE Plasma 6, versioned 6.2.3.

Plasma 6.2 was released in October 2024 with many feature refinements and new modules to complete the desktop experience.

This release adds two weeks' worth of new translations and fixes from KDE's contributors. The bugfixes are typically small but important and include:

• Bluedevil: Correct PIN entry behavior. Commit.
• KWin: Backends/drm: don't set backlight brightness to 1 in HDR mode. Commit. Fixes bug #495242
• KDE GTK Config: Gracefully handle decoration plugin failing to load. Commit.

View full changelog

In the Qt 6.7 release, we enabled support for C++20 comparison and also back-ported some of its features to C++17. This blog post will give you an overview of the comparison enhancements we are taking advantage of and offer guidance on implementing them in your custom classes.

Dolphin's accessibility, Itinerary's travelling aids, and a bunch of new upcoming KDE apps

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.

In this issue we discover what developers have been doing to make Dolphin, KDE's most popular (but not only!) file explorer, more accessible. We also take a look at all the new services now integrated into Itinerary that will help you on your travels, the new features for Kate that programmers will enjoy, improvements to Kleopatra to help you manage your certificates and the encryption of your messages, and the flurry of new applications that will soon be available in KDE's software catalog.

This week, we also kicked off our 2024 end-of-year fundraiser just in time for Halloween! 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. So consider doing a donation today!

Let's dig in!

Dolphin Manage your files

We improved the keyboard navigation of Dolphin, as pressing Ctrl+L multiple times will switch back and forth between focusing and selecting the location bar path and focusing the view. Pressing Escape in the location bar, will now move the focus to the active view (Felix Ernst, 24.12.0. Link).

Speaking of accessibility, the accessibility of the main view of Dolphin was completely overhauled to make it work with screen readers. This work was funded by NGI0 Entrust Fund, a fund established by NLnet with financial support from the European Commission's Next Generation Internet programme (Felix Ernst, 24.12.0. Link).

Another change is that Dolphin will now store its view properties inside the extended file attributes instead of creating hidden .directory files when possible (Méven Car, 24.12.0. Link).

digiKam Photo Management Program

digiKam is KDE's powerful photo management software for both professional and aficionado photographers.

Michael Miller fixed an issue where faces from the facial recognition feature were not deleted when a user untagged or deleted a face (Michael Miller. Link).

Elisa Play music and listen to online radio stations

Jack Hill fixed a few issues related to the lyrics feature. Clicking on the Lyrics button now takes you to the correct lyric and not the previous one, and the last line of the lyrics is not displayed completely (Jack Hill, 24.12.0. Link).

Jack also reworked the metadata dialogs to be more intuitive and correct some bugs (Jack Hill, 24.12.0. Link).

GCompris Educational game for children

GCompris, the educational software suite, got a new activity: Sketch! This fun tool lets children express their creativity and draw beautiful artworks (Timothée Giet. Link).

KDE Itinerary Digital travel assistant

Itinerary now supports extracting reservations from planway.com, flight tickets from VietJet Air and train tickets from the Thai state railway. Additionally, dates from day-specific train tickets from NS (Nederlandse Spoorwegen) are now correctly parsed (Volker Krause, 24.08.3. Link 1, link 2, link 3), and, while on an NS intercity train, you can also access the live journey information provided by the onboard WiFi (Carl Schwan, 24.12.0. Link).

Kate Advanced Text Editor

Kate continues to become more and more developer friendly with the changes made by Christoph Cullmann where the order of the tabs is correctly restored when restoring a previous session (Christoph Cullmann, 24.08.3. Link), and the options of the LSP Symbols are more easily discoverable as they are not only available via a context menu, but also within a menu button at the top (Waqar Ahmed, 24.12.0. Link).

Benjamin Port fixed the Appium UI tests and reenabled them on the CI (Benjamin Port, 28.03.0. Link).

Kdenlive Video editor

Kdenlive is KDE's full-featured video editor, which now lets you resize multiple items on the timeline at the same time. (Jean-Baptiste Mardelle, 24.12.0 Link).

Kleopatra Certificate manager and cryptography app

We redesigned Kleopatra's notepad and sign encrypt dialog. In the notepad, the text editor and the recipients view are also now side by side (Carl Schwan, 24.12.0. Link).

Additionally, Tobias worked on the notepad's result messages and error dialogs to make them clearer. (Tobias Fella, 24.12.0 Link 1, link 2).

Tobias also fixed a crash on non-kwin Wayland compositors (Tobias Fella, 24.08.3. Link), and Kleopatra has a new website (Carl Schwan. Link).

Kongress Conference companion

Kongress is an app which helps you navigate conferences and events.

The newest version will display more information about events in the event list. This includes whether the event is in your bookmarked events and the locations within the event (e.g. the rooms) (cah fof pai, 24.12.0. Link).

Speaking of conferences, multiple KDE people will be at the Chaos Communication Congress (38c3) in Hamburg this December! Come by and say hello!

KStars Desktop Planetarium

KStars is KDE's stargazing app that also helps you control your telescope for astrophotography.

We removed the "Simulate Eyepiece View" feature and stripped down EyepieceField. The reason is the offerings of the eyepiece view feature have already been superseded by two more powerful and easier-to-use features in KStars: the HiPS Overlay and the "Views" feature (Akarsh Simha, 3.7.4. Link).

Kwave Sound editor

Mark Penner wrote a blog post about his work on KWave.

LabPlot Interactive Data Visualization and Analysis

LabPlot is KDE's complete suite of data analysis and visualisation tools.

The LabPlot developers added the RAND_MAX programming constants for GSL (GNU Scientific Library) support. (Martin Marmsoler Link), and rewrote the AsciiFilter to increase the parsing speed, like when parsing livedata from an mqtt feed (Martin Marmsoler. Link).

Kuntal Bar also fixed various issues with HiDPI screens (Kuntal Bar, Link).

Marknote Write down your thoughts

Marknote lets you create rich text notes and easily organise them into notebooks.

The icons in the app are now correctly displayed when running Marknote on other platforms, like Windows (Gary Wang, Link).

Ruqola Rocket Chat Client

Ruqola, KDE's Rocket Chat client, received various fixes for its login, logout and network disconnection features (David Faure & Andras Mantia Link 1, link 2, link 3 and link 4), and the unread message bar now uses buttons instead of more subtle links (Joshua Goins. Link).

Spectacle Screenshot Capture Utility

Spectacle is the utility for taking screenshots and screencasts of your desktop and apps. We fixed an issue where Spectacle would take a screenshot of itself (Noah Davis, 24.08.3. Link).

Other Stuff

The FormCard components used by most Kirigami application are now more compact on the desktop (Carl Schwan, Kirigami Addons 1.6.0 Link).

Before After

The About Page provided by the FormCard component now displays more information about the components used by the application (e.g. Qt, KDE Frameworks) (Carl Schwan, Kirigami Addons 1.6.0. Link).

Playground

This section contains news about non released applications.

Arkade

Arkade, a collection of games written in QML, was updated to Qt6 (Carl Schwan. Link).

Whale

Claudio Cambra ported Whale, a QML based file manager and explorer, to Qt6 (Claudio Cambra. Link). Claudio also added a miller columns view to Whale (Claudio Cambra. Link), and implemented navigation history (Claudio Cambra. Link).

And all this too...

Justin Zobel fixed various appstream files to use the new way of declaring the developer's name (Justin Zobel, KRuler, Gwenview, KEuroCalc, ...).

We ported various projects to use declarative QML declaration for better maintainance and performance (Carl Schwan, Koko, Francis, Kalk).

... 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.

Surprise! This blog post series has now been moved to blogs.kde.org so it’s now open for others to participate and contribute! This week’s post can be found at https://blogs.kde.org/2024/11/02/this-week-in-plasma-spoooooky-ooooooooom-notifications

That’s probably where it should have been all along, as this work is much bigger than me. I’ll remain the editor-in-chief for now, but do welcome contributions to help lighten the load.

Unfortunately, due to GDPR restrictions, I’m unable to migrate existing email subscribers to the new email digest over there. So if you’d like to re-subscribe to “This week in Plasma.” head to https://newsletter.kde.org/subscription/form and re-subscribe.

I’ll still be blogging here about KDE topics of interest to me and hopefully you as well, just not the weekly Plasma news. So I do hope you’ll stick around.

Welcome to the new home of "This Week in Plasma"! No longer is it a private personal thing on my (Nate Graham's) blog, but now it's a weekly series hosted here on KDE's infrastructure, open to anyone's participation and contribution! I'll remain the editor-in-chief for now, and welcome contributions via direct push to the relevant merge request on invent.kde.org. And after a post is published, if you find a typo or broken link, feel free to just fix it.

Anyway, this week we added a useful service to detect out-of-memory (OOM) conditions, did some UI polishing, and also a lot of bug-fixing! Check it out:

Notable New Features

When the system has run out of memory (OOM) and the kernel terminated an app, there's now a little service to detect this and show you a system notification explaining what happened, plus suggestions for what you can do about it in the future. (Harald Sitter, 6.3.0. Link)

Notable UI Improvements

The Emoji Selector app now does sub-string matching from the middle of words too, so you can find emojis more easily. (Eren Karakas, 6.2.3. Link)

The grouping indicator in the Task Manager widget (which looks like a little plus sign) is no longer always green; now it follows the current accent color! (Tem PQD, 6.3.0. Link)

Appropriate symbolic icons from will now be automatically substituted for apps' system tray icons — when they exist in the icon theme. If you'd like to extend this to more apps, figure out what icon name the app asks for, then create a symbolic version of it, append -symbolic to the name, and submit it to the Breeze Icons repo! (Marco Martin, 6.3.0. Link)

Notable Bug Fixes

Fixed a way that misbehaving XWayland-using apps could make KWin freeze. (Vlad Zahorodnii, 6.2.3. Link)

Fixed a bug causing notifications about modifier key changes (if you've turned them on) to not actually appear. (Nicolas Fella, 6.2.3. Link)

Fixed a bug in the Bluetooth pairing wizard that caused it to be annoying to enter digits. (Daniil-Viktor Ratkin, 6.2.3. Link)

Reviews on Discover's app pages now load properly when the app is accessed from the Home page, as opposed to after browsing or searching. (Aleix Pol Gonzalez, 6.2.3. Link)

Fixed the Task Manager widget's setting to reverse the direction that new tasks appear in so that it works as originally designed, and not only halfway there. (Michael Rivnak, 6.2.3. Link)

Fixed a bug that caused customized user avatars for other currently-logged-in users to not be displayed in the User Switcher widget. (Blazer Silving, 6.2.3. Link)

Fixed a bug causing the "Show Logout Screen" item in the desktop context menu to not show enough items if you had customized the "default logout option" in the past, back when we offered that as a user-facing setting. (Nate Graham, 6.2.3 Link)

With global animations set to "instant", window thumbnails in KWin's Desktop Grid effect are no longer too small. (Niccolò Venerandi, 6.2.3. Link)

When you've got the Application Dashboard widget set up with an icon naming style that causes the text to be long and get elided, hovering over the icon now shows a tooltip with the correct full text in it. (Tomislav Pap, 6.2.3. Link)

Fixed a case where KWin could crash when moving certain drawing tablet pens to the surface of the pad. (Vlad Zahorodnii, 6.3.0. Link)

Fixed an issue that caused XWayland-using apps to resize in a janky and jumpy manner. (Vlad Zahorodnii, 6.3.0. Link, see detailed blog post)

How You Can Help

KDE has become important in the world, and your time and contributions have helped us get there. As we grow, we need your support to keep KDE sustainable.

You can help KDE by becoming an active community member and getting involved somehow. 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. Many other opportunities exist:

• Filter and confirm bug reports, maybe even identify their root cause
• Contribute designs for wallpapers, icons, and app interfaces
• Design and maintain websites
• Translate user interface text items into your own language
• Promote KDE in your local community
• …And a ton more things!

You can also help us by donating to our yearly fundraiser! 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 a new Plasma feature or a bugfix mentioned here, feel free to push a commit to the relevant merge request on invent.kde.org.

In Plasma 6.2, KWin switched from doing linear blending with HDR to blending in a gamma 2.2 space. Let’s take a look at what that means, and why it was done.

What is blending?

When KWin composites, it paints window by window, going by the order of how the windows are stacked - the bottom-most window first, the topmost window last. When a window is opaque, you just overwrite the pixels in the framebuffer with the ones from the window. When a window is semi-transparent though, we need to additionally do blending.

To do blending, the GPU calculates the value that the framebuffer should have with some equation that gets the pixel from the window and the existing value in the framebuffer, and outputs some appropriate value. Usually that equation is1

framebuffer = framebuffer.rgb * (1 - window.alpha) + window.rgb * window.alpha

where window.alpha is a per-pixel value that describes how opaque the pixel is.

Blending with color management

In Plasma 5, compositing happened in the display color space. As displays could be assumed to be roughly the same, with brightness levels encoded in sRGB, that resulted in blending looking very similar everywhere.

With HDR in Plasma 6 however, that assumption was no longer true, so we had to do something else. As it was considered the most “correct” thing and allows us to ensure the exact same blending result even with displays that have wildly different colorspaces, linear blending was chosen for Plasma 6.0. The result of linear blending would look different from sRGB, but it would at least be consistent everywhere.

With linear blending, instead of just taking the rgb values as is, you first convert them into light-linear values, for example with sRGB you’d just do

rgb_linear = pow(rgb_sRGB, 2.2)

then apply the blending equation, and at the end convert it back to whatever encoding the screen needs.

Because of limitations in KWin’s renderer and the ancient OpenGL versions KWin supports, the only way to do this was to render first into a so-called shadow buffer2 with linear values, and after compositing a second shader pass would run, taking that shadow buffer as the input and outputting a buffer with non-linear values that’s suitable for sending to the screen.

The caveats of linear blending

It’ll be pretty obvious to most that doing a fullscreen copy each frame is not ideal for performance or battery life, but there was even a second problem: If you use only 8 or 10 bits per color (bpc) to store linear brightness values, you get visible banding in the dark areas of the image, as human vision is very non-linear. So on top of doing fullscreen copies, KWin also had to use a floating point buffer with 16 bpc, which uses twice the memory bandwidth vs. 8 bpc and makes performance and power usage even worse.

With that performance hit, we couldn’t enable this on all hardware, but had to restrict linear blending to those displays where HDR or an ICC profile is enabled. This threw the whole consistency benefit out of the window, because now a semi-transparent surface would look a lot more transparent just because you enabled HDR… causing the very problem we wanted to avoid!

SDR HDR

We had to do something when blending in HDR though, so a different approach had to be taken.

Custom transfer functions

When storing colors in buffers, usually we use non-linear encodings with transfer functions like sRGB or PQ. All the transfer functions have some sort of luminance levels attached to them, for example an sRGB value of 1.0 is defined to result in a luminance of 80 nits in its reference viewing environment3.

There’s no reason to be restricted to those definitions though - we can make transfer functions that mean whatever we want or need. In KWin’s case, we switched the shadow buffer from using a linear encoding to a gamma 2.2 encoding, in which 1.0 means the maximum luminance of your monitor. This means we do blending in a very similar way as on SDR screens4, and translucent surfaces on the screen look pretty much the same again, no matter what display settings you have.

As the gamma 2.2 encoding allocates more numbers to darker parts of the image, we can also avoid banding with fewer bits per color. Whenever HDR is enabled and the driver supports buffers with 10 bpc, KWin now prefers to use that instead of 16 bpc, alleviating some of the performance issues. There was still more that could be done though…

KMS offloading

On most graphics cards, the scanout hardware that takes care of sending the image to the display has some fixed function blocks to change the colors in various ways - the most common being a simple look up table (LUT) per color channel.

Through the DRM/KMS API, the compositor can set this LUT, so we can use it to change the encoding from whatever we did blending in to the one the display needs. With HDR screens, this means we

• convert from our shadow buffer encoding with gamma 2.2 and the maximum luminance of the screen to linear
• possibly apply rgb factors for night light
• convert from linear to the PQ encoding the screen needs

With that LUT in place, we don’t have to run a shader pass to convert from the shadow buffer encoding to the screen anymore, so the whole fullscreen copy falls away.

Except for a few additional instructions in the shaders used for compositing, enabling HDR in Plasma 6.2 thus has no performance impact anymore on the vast majority of hardware!

1. in practice, window.rgb is already “pre-multiplied” with window.alpha, but that doesn’t really matter here ↩

2. it’s called that because it’s never actually shown on the screen ↩

3. the viewing environment basically defines a standardized room, in which the content can be viewed as intended without doing any brightness adjustments ↩

4. it’s not exactly the same though. If you need some exactly specific blending behavior in your application, it’s best if you do it yourself ↩

Let’s go for my web review for the week 2024-44.

What You Can Learn from Just Seven Pages by Hannah Arendt

Tags: tech, philosophy, history, politics

A very precious philosopher from the 20th century. Her texts are still very precious and resonate today. In this piece it’s focusing about tech relevant excerpts, she had plenty to say about today’s politics as well.

https://www.honest-broker.com/p/what-you-can-learn-from-just-seven

The Open Source AI Definition

Tags: tech, foss, ai, machine-learning

Nice initiative from the OSI. It is timely, such a definition was surely needed. The data information part seems fairly weak though… for sure you could make a system which doesn’t respect the four freedoms that way.

https://opensource.org/ai/open-source-ai-definition

Does Open Source AI really exist?

Tags: tech, foss, ai, machine-learning

Like me, you find the Open Source AI Definition weak on the training data information side? You’d be right and there’s a reason for it… it’s probably hiding quite some open washing for the larger models. This is a good explanation of the motives and consequences.

https://tante.cc/2024/10/16/does-open-source-ai-really-exist/

Platform Strategy and Its Discontents

Tags: tech, web, mobile, react, framework, criticism

This is definitely true. As long as web frontends are dominated by large frameworks, the web will always have subpar experience on mobile. And the solution isn’t going to come from the mobile providers too happy to gatekeep their app store.

https://infrequently.org/2024/10/platforms-are-competitions/#fn-failure-on-repeat-2

Matrix 2.0 Is Here!

Tags: tech, matrix, protocols

This is definitely getting there in terms of performance and usability. The mobile clients seem mature enough, just need the desktop clients to catch up before this becomes really something I’d feel confident enough to recommend and push for.

https://matrix.org/blog/2024/10/29/matrix-2.0-is-here/

What’s New in POSIX 2024

Tags: tech, unix, posix

It’s nice to see the standard still moves. Some of the additions are definitely welcome.

https://blog.toast.cafe/posix2024-xcu

Australia/Lord_Howe is the weirdest timezone

Tags: tech, time, culture, internationalization

Time management and timezones are definitely complicated. In a way it’s culture colliding with computers and localisation… it can’t be simple.

https://ssoready.com/blog/engineering/truths-programmers-timezones/

Improving SSH’s security with SSHFP DNS records

Tags: tech, tools, ssh, dns, security

Nice technique for automating the verification of SSH host keys. It’d be nice to see wider adoption.

https://blog.apnic.net/2022/12/02/improving-sshs-security-with-sshfp-dns-records/

Introducing zizmor: now you can have beautiful clean workflows

Tags: tech, github, ci, security, tools

Definitely an interesting tool. GitHub Actions workflow aren’t easy to setup while ensuring they’re secure, having a tool analyzing them for issues can only help.

https://blog.yossarian.net/2024/10/27/Now-you-can-have-beautiful-clean-workflows

Toward safe transmutation in Rust

Tags: tech, rust, type-systems, memory

Interesting progress on safe type casting in Rust. This should bring nice zero copy parsing of binary data in some cases.

https://lwn.net/SubscriberLink/994334/5e1f97f08916b494/

Lessons learned from a successful Rust rewrite

Tags: tech, c++, rust, legacy

This is a good view of what you’re getting into with the “rewrite it in Rust” knee-jerk reaction.

https://gaultier.github.io/blog/lessons_learned_from_a_successful_rust_rewrite.html

Vector Databases Are the Wrong Abstraction

Tags: tech, postgresql, databases, ai, machine-learning, language

I definitely like the approach of having vectorisation in the RDBMS directly. This is one less moving part, less complexity at the application level to synchronize everything together. In this case it’s a Postgres extension.

https://www.timescale.com/blog/vector-databases-are-the-wrong-abstraction/

Database Remote-Copy Tool For SQLite

Tags: tech, sqlite, databases, tools

Interesting, there’s now an official tool to replicate sqlite databases. It’s still early days, we’ll see which features it’ll get.

https://sqlite.org/rsync.html

How to profile a performance issue using Spring Boot profiling tools

Tags: tech, java, spring, profiling

A quick tour of the available tools to profile Spring Boot applications.

https://foojay.io/today/how-to-profile-a-performance-issue-using-spring-boot-profiling-tools/

Working with stacked branches in Git is easier with –update-refs

Tags: tech, git, tools

Yet another Git option I missed. This is definitely useful, I’ll try it out.

https://andrewlock.net/working-with-stacked-branches-in-git-is-easier-with-update-refs/

pygfx

Tags: tech, python, 3d, webgpu, data-visualization

Looks like a very interesting Python library to build interactive 3d visualizations.

https://docs.pygfx.org/stable/index.html

Rudimentary 3D on the 2D HTML Canvas

Tags: tech, 2d, 3d, graphics, mathematics

Ever wondered how to simulate 3D from 2D based primitives? Here is a nice experiment explaining how to approach it.

https://www.charlespetzold.com/blog/2024/09/Rudimentary-3D-on-the-2D-HTML-Canvas.html

Classic 3D videogame shadow techniques

Tags: tests, 3d, graphics

A nice list of the techniques used to render shadows in games.

https://30fps.net/pages/videogame-shadows/

On Crafting Painterly Shaders

Tags: tech, 3d, graphics, shader

Very nice deep dive into a post-processing shader to create a painted scene effect.

https://blog.maximeheckel.com/posts/on-crafting-painterly-shaders/?ck_subscriber_id=2669647738

The Basics

Tags: tech, craftsmanship, learning, career

Indeed, those are fundamental traits to make sure you learn and make progress on your journey.

https://registerspill.thorstenball.com/p/the-basics

Background Work - by Kent Beck

Tags: tech, learning, career, craftsmanship

Another excellent piece from Kent Beck, he’s right that the real differentiator in our profession is about digging deep on topics, seeing them through even if that’s on the side. Curiosity is a key trait.

https://tidyfirst.substack.com/p/background-work

the death of the architect

Tags: tech, agile, architecture, history

Good explanation on how the agile movement scaled down about design over time in its literature. It’s probably its biggest failure. The good thing is that the pendulum is starting to swing in the other direction a bit (that’s probably why Beck is now working on a book series on software design).

https://explaining.software/archive/the-death-of-the-architect/

How to make Product give a shit about your architecture proposal

Tags: tech, quality, product-management, project-management

This is accurate in my opinion. Engineering and product teams need to properly negotiate, otherwise quality will suffer.

https://gieseanw.wordpress.com/2024/10/09/how-to-make-product-give-a-shit-about-your-architecture-proposal/

How to not be a prioritization machine

Tags: tech, project-management, product-management, decision-making

Interesting guidelines idea to help teams manage the priorities themselves. It’s written in the context of a product manager but I think it is lightweight and generic enough to apply in other contexts.

https://productmanagers.substack.com/p/how-to-not-be-a-prioritization-machine

We Fell For The Oldest Lie On The Internet

Tags: science, complexity

It’s sometimes extremely difficult to get to the original source of a scientific claim. Our corpus of science is so large and complex now that finding where a claim comes from can be a daunting task.

https://www.youtube.com/watch?v=bgo7rm5Maqg

Changes in primary visual and auditory cortex of blind and sighted adults following 10 weeks of click-based echolocation training | Cerebral Cortex | Oxford Academic

Tags: science, neuroscience

This is an amazing example of the brain plasticity. It’s also great to have a patch for increased quality of life with a training of only a few weeks.

https://academic.oup.com/cercor/article/34/6/bhae239/7696241?login=false

Bye for now!

The Qt Quick 3D project was first announced and released in 2019. Since then, it has seen numerous enhancements. We have concentrated on boosting performance, introducing new features, and expanding the module's capabilities.

I had previously mentioned efforts on bringing public emergency and weather alerts to free software and free infrastructure, which was also my initial motivation to work on push notifications. With that moving forward it’s time to explain a bit more what’s happening there.

FOSS Public Alert Server

As part of the initial push notification work I had written a simple prototype server which aggregates alerts from about a hundred countries and allows clients to subscribe to be notified about alerts in a given area of interest.

With the push notification client and server parts for KDE released and deployed, that’s now the next thing to tackle.

After teaming up with FOSS Warn (a free alternative to the proprietary emergency and weather alert apps in Germany), who need the same kind of infrastructure there’s now even NLnet funding to turn this into production-ready software.

Work is going to happen in this repository on KDE’s Gitlab instance, and can be followed on this Mastodon account.

Public emergency alert push notification. Common Alerting Protocol (CAP)

For this to scale globally we need standardized data models, data formats and protocols. And thankfully those exist in form of OASIS’ Common Alerting Protocol (CAP) since many years and are widely in use.

CAP describes an XML format for alert messages, covering categorization, severity, certainty, urgency, affected area, and multi-lingual descriptions and instructions.

Build on top of that are CAP feeds, which are basically RSS or Atom feeds of CAP alert messages.

There’s also a bunch of national- or agency-specific profiles which for example define additional information elements or specify the use of existing fields more precisely for their use-case.

From a technical point of view none of that is particularly challenging, we already have support for CAP alerts in KWeatherCore for example.

CAP is widespread for internal use in various international, national or sub-national emergency warning systems, for connecting alerting authorities with e.g. media broadcast or mobile network providers. In many countries CAP feeds are also publicly available, which is the interesting part for us here.

CAP Workshop

After having gotten in touch with other people working in this area we got invited to the CAP Workshop that happened last week, a rather unassuming name for a three day international conference with national delegations from more than 120 countries, several UN agencies and NGOs like the International Red Cross/Crescent, and quite a bit more formal than what we are used to from other events.

Unfortunately I couldn’t be there in person and only followed this online, but even that provided quite some interesting insights.

• OASIS’ work on extended event codes, which should help with better display and filtering of alerts in client applications.
• Several talks covered the “usability” of alerts, ie. how to word/present warnings so that they are understood by everyone and so that they result in the intended reaction. Much of this is in the hands of the alert issuers, but client software can help here as well, e.g. regarding accessibility (TTS, both visual and audible notifications, translations and understandable language in general, etc).
• Google showed the various places where they integrate alerts in their products: displayed on maps, discoverable via search, location-dependent push notifications, integrated with weather forecasts and in routing before entering an affected area. Can be inspiration for what we could do as well.
• A talk presented work on Mexico’s earthquake early warning system. As earthquakes can’t be predicted this uses the fact that an alert can outrace the shockwave and thus might still reach people further away in time (same as tsunami warnings work, just at a much shorter timescale). Their estimate from a simulation of past earthquakes was 10 seconds making a difference of 10k lives. That’s a level of responsiveness our current CAP feed polling approach is not going to be able to reach, this would need direct listening to the alert radio signals.
• There’s several CAP feeds that aren’t publicly available yet, whenever such a case came up there was push for changing that in the following Q&A session. Good, we need that.

How you can help

There’s plenty of things to do here. On the software development side there’s getting the server code production ready and deployed, building monitoring tools for that and turning the demo app into a reuable client library and integrating that in places where it makes sense.

Equally important though is finding more CAP feeds and in some cases additional data sets to resolve area codes used in the alerts to geographic polygons. This is something that often needs local knowledge and understanding the local languages. And where there are no CAP feeds yet, nagging your local authorities to change that also helps.

We should soon get a dedicated Matrix channel for coordinating this, and we’ll be at 38C3 and FOSDEM 2025 if you want to talk about this in person.

We are happy to announce the release of Qt Creator 15 Beta2!

In an era where digital security is paramount, the European Union is taking steps to improve cybersecurity legislation with the introduction of the European Union Cyber Resilience Act (CRA). As the European Union has now adopted the CRA, Qt Group continues to work towards making our products CRA compliant and supporting our customers with their compliancy.