Kube is still alive! I got distracted for a while, both professionally and privately, and writing blog posts is unfortunately always the first thing that ends up on the chopping block. Anyways, lot’s of progress has been made (103 commits in sink, ~130 commits in the kube codebase):

• For sink we had a variety of bugfixes and performance improvements, especially on the more recent CalDAV/CardDAV backends.
• For CalDAV/CardDAV we now do basic autodiscovery using the .well-known url’s. The DNS part of the spec has not been implemented so far.
  This means for a properly set-up server you only have to specify the base url, and everything else will be discovered automatically from there.
• On the more user-facing front we have:
  • Sent emails are now collapsed by default
  • Plain text is now the preferred method of viewing emails. You can still view the HTML variant if available by clicking a button.
    • The Addressbook is no longer read-only and you can now create contacts as well.
  • A visually reworked composer that avoids becoming too wide and removes a lot of the visual clutter.
  • The calendar can now render recurring-events.
  • It is now possible to create events as well.
  • Work on a tasks view has started

Releases

You may have noticed that it’s been a while since the last release. This is not only because releases are additional work, but also because we already have a continuous delivery method with the nightly flatpak.
It’s clear that releases do provide value, both as a communication tool which version should be packaged, and if they would be maintained. With the current manpower we cannot maintain releases though, which makes it significantly less interesting.

With that said, the 0.8 release with the calendar is now long overdue and should be coming out soonish.

Experimental flatpak

Just to put it out there; Additionally to the usual “master” branch of the flatpak, there is also an “experimental” branch, containing, surprise, various experimental bits and pieces.

This currently entails:

• A plugin that stores the accounts password encrypted by the accounts gpg key (blindly assuming there is one with a matching email address).
• A search view
• The upcoming calendar view (which we’ll move over in the next release)
• The above todo view (which will take a little longer to move to master)
• A “File as expense” plugin (a showcase how we could do extensions in the mail view).
• The Inbox crusher view (an experiment for a view to go through your inbox one-by-one).

It typically serves as a staging ground for new components, and is the version that I’m running day-to-day. flatpak makes it easy to switch back and forth between the branches on top of the same dataset, so you can try it and switch back if you don’t like what you see.

To give it a shot use the following command to switch the current flatpak branch:

flatpak --user make-current com.kubeproject.kube experimental

Kube Commits, Sink Commits

Previous updates

More information on the Kolab Now blog!

“Kube is a modern communication and collaboration client built with QtQuick on top of a high performance, low resource usage core. It provides online and offline access to all your mail, contacts, calendars, notes, todo’s and more. With a strong focus on usability, the team works with designers and UX experts from the ground up, to build a product that is not only visually appealing but also a joy to use.” For more info, head over to: kube-project.com

Although kdesrc-build supports building Qt5 just like the KDE Frameworks, I prefer to use the prebuilt Qt binaries from qt.io for testing against alpha and beta releases. This saves me a lot of time on my machine, which is not powerful enough to compile the full Qt in a reasonable time.

This guide assumes that you already installed Qt from qt.io/download-qt-installer.

To reproduce my setup, an additional step is required compared to a kdesrc-build setup that uses the system Qt, nevertheless you start as usual, by cloning kdesrc-build itself:

git clone https://invent.kde.org/kde/kdesrc-build

Since kdesrc-build should be available anywhere on the system, not just in its own directory, we add it to the PATH variable by appending export PATH=~/kde/src/kdesrc-build:$PATH to your .profile file. Please remember to adapt the path according to where you cloned kdesrc-build to.

echo "export PATH=~/kde/src/kdesrc-build:$PATH" >> ~/.profile
source ~/.profile

Next, the initial setup needs to be performed:

kdesrc-build --initial-setup

This step created all the required configuration files, which now need slight adaptions in order to work with the Qt we downloaded from qt.io in the beginning.

Edit ~/.kdesrc-buildrc, and replace the path to Qt qtdir with the path you installed Qt to. The line should then look similar to this:

    qtdir  ~/.local/Qt/5.13.0/gcc_64 # Where to find Qt5

Now as a final step we need to prevent kdesrc-build from trying to build its own Qt, which can be done by commenting one include line: include /home/jbb/kde/kdesrc-build/qt5-build-include, so it looks like #include /home/jbb/kde/kdesrc-build/qt5-build-include.

This should be it! Have fun compiling up to date KDE software using an up to date Qt without compiling Qt for hours :)

kdesrc-build kirigami --include-dependencies

To activate your newly created environment, you can use

source ~/.config/kde-env-master.sh

The bug report count of KTextEditor (implementing the editing part used in Kate/KWrite/KDevelop/Kile/…) and Kate itself reached again some value over 200.

If you have time and need an itch to scratch, any help to tackle the currently open bugs would be highly appreciated.

The full list can be found with this bugs.kde.org query.

Easy things anybody with a bit time could do would be:

• check if the bug still is there with current master builds, if not, close it it
• check if it is the duplicate of a similar still open bug, if yes, mark it as duplicate

Beside that, patches for any of the existing issues are very welcome.

I think the best guide how to setup some development environment is on our KDE Community Wiki. I myself use a kdesrc-build environment like described there, too.

Patches can be submitted for an review via our KDE Phabricator.

If it is just a small change and you don’t want to spend time on Phabricator, attaching a git diff versus current master to the bug is ok, too. Best mark the bug with a [PATCH] prefix in the subject.

The team working on the code is small, therefore please be a bit patient if you wait for reactions. I hope we have improved our reaction time in the last months but we still are lacking in that respect.

Would you like your C++ code to compile twice as fast (or more)?

Yeah, so would I. Who wouldn't. C++ is notorious for taking its sweet time to get compiled. I never really cared about PCHs when I worked on KDE, I think I might have tried them once for something and it didn't seem to do a thing. In 2012, while working on LibreOffice, I noticed its build system used to have PCH support, but it had been nuked, with the usual poor OOo/LO style of a commit message stating the obvious (what) without bothering to state the useful (why). For whatever reason, that caught my attention, reportedly PCHs saved a lot of build time with MSVC, so I tried it and it did. And me having brought the PCH support back from the graveyard means that e.g. the Calc module does not take 5:30m to build on a (very) powerful machine, but only 1:45m. That's only one third of the time.

In line with my previous experience, on Linux that did nothing. I made the build system support also PCH with GCC and Clang, because it was there and it was simple to support it too, but there was no point. I don't think anybody has ever used that for real.

Then, about a year ago, I happened to be working on a relatively small C++ project that used some kind of an obscure build system called Premake I had never heard of before. While fixing something in it I noticed it also had PCH support, so guess what, I of course enabled it for the project. It again made the project build faster on Windows. And, on Linux, it did too. Color me surprised.

The idea must have stuck with me, because a couple weeks back I got the idea to look at LO's PCH support again and see if it can be made to improve things. See, the point is, PCHs for that small project were rather small, it just included all the std stuff like <vector> and <string>, which seemed like it shouldn't make much of a difference, but it did. Those standard C++ headers aren't exactly small or simple. So I thought that maybe if LO on Linux used PCHs just for those, it would also make a difference. And it does. It's not breath-taking, but passing --enable-pch=system to configure reduces Calc module build time from 17:15m to 15:15m (that's a less powerful machine than the Windows one). Adding LO base headers containing stuff like OUString makes it go down to 13:44m and adding more LO headers except for Calc's own leads to 12:50m. And, adding even Calc's headers, results in 15:15m again. WTH?

It turns out, there's some limit when PCHs stop making things faster and either don't change anything, or even make things worse. Trying with the Math module, --enable-pch=system and then --enable-pch=base again improve things in a similar fashion, and then --enable-pch=normal or --enable-pch=full just doesn't do a thing. Where it that 2/3 time reduction --enable-pch=full does with MSVC?

Clang has recently received a new option, -ftime-trace, which shows in a really nice and simple way where the compiler spends the time (take that, -ftime-report). And since things related to performance simply do catch my attention, I ended up building the latest unstable Clang just to see what it does. And it does:

Elisa is a music player developed by the KDE community that strives to be simple and nice to use. We also recognize that we need a flexible product to account for the different workflows and use-cases of our users.

We focus on a very good integration with the Plasma desktop of the KDE community without compromising the support for other platforms (other Linux desktop environments, Windows and Android).

We are creating a reliable product that is a joy to use and respects our users privacy. As such, we will prefer to support online services where users are in control of their data.

I am happy to announce the release of 0.4.0 version of the Elisa music player.

The new features are explained in the following posts New features in Elisa, New Features in Elisa: part 2 and Elisa 0.4 Beta Release and More New Features.

There have been a couple more changes not yet covered.

Improved Grid Views Elements

Nate Graham has reworked the grid elements (especially visible with the albums view).

I must confess that I was a bit uneasy with this change (it was a part mostly unchanged since the early versions). I am now very happy about this change.

Before

After

Getting Involved

I would like to thank everyone who contributed to the development of Elisa, including code contributions, testing, and bug reporting and triaging. Without all of you, I would have stopped working on this project.

New features and fixes are already being worked on. If you enjoy using Elisa, please consider becoming a contributor yourself. We are happy to get any kind of contributions!

We have some tasks that would be perfect junior jobs. They are a perfect way to start contributing to Elisa. There are more not yet reported here but reported in bugs.kde.org.

The flathub Elisa package allows an easy way to test this new release.

Elisa source code tarball is available here. There is no Windows setup. There is currently a blocking problem with it (no icons) that is being investigated. I hope to be able to provide installers for later bugfix versions.

The phone/tablet port project could easily use some help to build an optimized interface on top of Kirigami. It remains to be seen how to handle this related to the current desktop UI.

I’m very excited to start off the Google Summer of Code blogging experience regarding the project I’m doing with my KDE mentors David Edmundson and Nate Graham. What we’ll be trying to achieve this summer is have SDDM be more in sync with the Plasma desktop. What does that mean? The essence of the problem...... Continue Reading →

If you occassionally do performance profiling as I do, you probably know Valgrind's Callgrind and the related UI KCachegrind. While Callgrind is a pretty powerful tool, running it takes quite a while (not exactly fun to do with something as big as e.g. LibreOffice).

Recently I finally gave Linux perf a try. Not quite sure why I didn't use it before, IIRC when I tried it somewhen long ago, it was probably difficult to set up or something. Using perf record has very little overhead, but I wasn't exactly thrilled by perf report. I mean, it's text UI, and it just gives a list of functions, so if I want to see anything close to a call graph, I have to manually expand one function, expand another function inside it, expand yet another function inside that, and so on. Not that it wouldn't work, but compared to just looking at what KCachegrind shows and seeing ...

When figuring out how to use perf, while watching a talk from Milian Wolff, on one slide I noticed a mention of a Callgrind script. Of course I had to try it. It was a bit slow, but hey, I could finally look at perf results without feeling like that's an effort. Well, and then I improved the part of the script that was slow, so I guess I've just put the effort elsewhere :).

And I thought this little script might be useful for others. After mailing Milian, it turns out he just created the script as a proof of concept and wasn't interested in it anymore, instead developing Hotspot as UI for perf. Fair enough, but I think I still prefer KCachegrind, I'm used to this, and I don't have to switch the UI when switching between perf and callgrind. So, with his agreement, I've submitted the script to KCachegrind. If you would find it useful, just download this do something like:

$ perf record -g ...
$ perf script -s perf2calltree.py > perf.out
$ kcachegrind perf.out

I have been at many software events and have helped or have been part of the organization in a few of them. Based on that experience and the fact that I have participated in the last two editions, let me tell you that J On The Beach is a great event.

The main factors that leads me to such a conclusion are:

• It is all about contents. I have seen many events that, over time, loose the focus on the quality of the contents. It is a hard focus to keep, specially as you grow. @JOTB19 had great content: well delivered talks and workshops, performed by bright people with something to say which was relevant to the audience.
  • I think the event has not reached its limit yet, specially when it comes to workshops.
  • Designing the content structure to target the right audience is as important as bringing speakers with great things to say. As any event matures, tough decisions will need to be taken in order to find its own space and identity among outstanding competitors.
    • When it comes to themes, will J On The Beach keep targeting several topics, or will it narrow them to one or two? Will they always be the same or will they rotate?
    • When it comes to size, will it grow or will it remain in the current numbers? Will the price increase or will be kept in the current range?
    • When it comes to contents, will the event focus more energy and time allocation on the “hands on” learning sessions or will workshops be kept as relevant compared to the talks, as they are today?  Will the talks length be reduced? Will we see lightning talks?
• J On The Beach was well organised. A good organization is not the one that does not run into any trouble but the one that handles them smoothly so there is little or no perceived impact. This event has a diligent team behind it, based on the little/no impact I perceived.
• Support from local companies. As Málaga matures as software hub, more and more companies arrive to this area expecting to grow in size, so the need to attract local talent grows in parallel.
  • Some of these foreign companies understand how important it is to show up in local events to be known by as many local developers as possible. J On The Beach has captured the attention of several of these companies.
  • The organizers have understood this reality and support them to use the event to openly  recruit people. This symbiotic relation is a very productive one from what I have witnessed.
  • It is a hard relation to sustain though, specially if the event does not grow is size, so probably in the future the current relation will need to add additional common interests to remain productive for both sides.
• Global by default. Most events in Spain have traditionally been designed for Spaniards first, turning into more global events as they grow. J On The Beach is global by default, by design, since day 1. It is harder to succeed that way, but beyond the activation point it turns out to be easier to become sustainable. The organizers took the risk and have reached that point already, which provides the event a bright future in my opinion.
  • The fact that the event is able to attract developers from many countries, specially from eastern European ones, makes J On The Beach very attractive to foreign companies already located in Málaga, from the recruitment perspective. Málaga is a great place not just to work in English but also to live in English. There are well established communities from many different countries in the metropolitan area, due to how strong the touristic industry is here. These factors, together with others like logistics, affordable living costs, good public health care system, sunny weather, availability of international and multilingual schools, etc., reduce the adaptation effort when relocating,  specially for developer’s families. J On The Beach brings tasty fishes to the pond.

Let me name a couple of points that can make the event even better:

• It is very hard to find a venue that fits any event during its consolidation phase and evolves with it. This edition’s venue represents a significant improvement compared to last year edition. There is room for improvement though.
  • It would be ideal to find a place in Málaga itself, closer to where the companies are located and places to hang out after the event, which at the same time, keep the good things the current venue/location provides, which are plenty.
  • Finding the right venue is tough. There are decision-making factors that participants do not usually see but are essential like costs, how supportive the venue staff and owners are, accommodation availability in the surrounding area, availability on the selected dates, etc. It is one of the most difficult points to get right, in my experience.                      
• Great events deserve great keynote speakers. They are hard to get but often reflects the difference between great and must-attend events.
  • Great keynote speakers does not necessarily mean popular ones. I see already celebrities in bigger and more expensive events. I would love to see in Málaga old time computer science cowboys.  I mean those first class engineers who did something relevant some time ago and have witnessed the evolution of our industry and their own inventions. They are able to bring a perspective that very few can provide, extremely valuable in these fast pace changing times. Those gems are harder to see at big/popular events and might be a good target for a smaller, high quality event. I think that it would be a great sign of success if such a kind of professionals come to talk at J On The Beach.

I am very glad there is such a great event close to where I live. J On The Beach is not just worth for local developers but also for those abroad. I attend to several events in other countries every year with more name but less value than J On The Beach. It will definitely be on my 2020 agenda. Thanks to every person involved in making it possible.

Pictures taken from the J On The Beach website.

Lacking VLC and libvlc in Craft, phonon-vlc cannot be built successfully on macOS. It caused the failed building of KDE Connect in Craft.

As a small step of my GSoC project, I managed to build KDE Connect by removing the phonon-vlc dependency. But it’s not a good solution. I should try to fix phonon-vlc building on macOS. So during the community bonding period, to know better the community and some important tools in the Community, I tried to fix phonon-vlc.

Fixing phonon-vlc

At first, I installed libVLC in MacPorts. All Header files and libraries are installed into the system path. So theoretically, there should not be a problem of the building of phonon-vlc. But an error occurred:

We can figure that the compiling is ok, the error is just at the end, during the linking. The error message tells us there is no QtDBus lib. So to fix it, I made a small patch to add QtDBus manually in the CMakeLists file.

1
2
3
4
5
6
7
8
9
10
11
12
13

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 47427b2..1cdb250 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -81,7 +81,7 @@ if(APPLE)
 endif(APPLE)
 
 automoc4_add_library(phonon_vlc MODULE ${phonon_vlc_SRCS})
-qt5_use_modules(phonon_vlc Core Widgets)
+qt5_use_modules(phonon_vlc Core Widgets DBus)
 
 set_target_properties(phonon_vlc PROPERTIES
     PREFIX ""

And it works well!

A small problem is that Hannah said she didn’t get an error during linking. It may be something about Qt version. If someone gets some idea, welcome to contact me.

My Qt version is 5.12.3.

Fixing VLC

To fix VLC, I tried to pack the VLC binary just like the one on Windows.

But unfortunately, in the .app package, the Header files are not completed. Comparing to Windows version, the entire plugins folder is missing.

So I made a patch for all those files. But the patch is too huge (25000 lines!). So it is not a good idea to merge it into master branch.

Thanks to Hannah, she has made a libs/vlc blueprint in the master branch, so in Craft, feel free to install it by running craft libs/vlc.

Troubleshooting

If you cannot build libs/vlc, just like me, you can also choose the binary version VLC with Header files patch.

The patch of Headers for binary is too big. Adding it to the master branch is not a good idea. So I published it on my own repository:
https://github.com/Inokinoki/craft-blueprints-inoki

To use it, run craft --add-blueprint-repository https://github.com/inokinoki/craft-blueprints-inoki.git and the blueprint(s) will be added into your local blueprint directory.

Then, craft binary/vlc will help get the vlc binary and install Header files, libraries into Craft include path and lib path. Finally, you can build what you want with libvlc dependency.

Conclusion

Up to now, KDE Connect is using QtMultimedia rather than phonon and phonon-vlc to play a sound. But this work could be also useful for other applications or libraries who depend on phonon, phonon-vlc or vlc. This small step may help build them successfully on macOS.

I hope this can help someone!

Hi, everyone!

I’m Weixuan XIAO, with the nickname: Inoki, sometimes Inokinoki is used to avoid duplicated username.

I’m glad to be selected in Google Summer of Code 2019 to work for KDE Community to make KDE Connect work on macOS. And I’m willing to be a long-term contributor in KDE Community.

As a Chinese student, I’m studying in France for my engineering degree. At the same time, I’m waiting for my bachelor degree at Shanghai University.

I major in Real-Time System and Embedded Engineering. With strong interests in Operating System and Computer Architecture, I like playing with small devices like Arduino and Raspberry Pi, different systems like macOS and Linux(especially Manjaro with KDE, they are the best partner).

Japanese culture makes me crazy, for example, the animation and the game. Even my nickname is actually the pronunciation of my real name in Japanese. So if all of these is the choice of Steins Gate, I’ll normally accept them :)

I speak Chinese, French, English, and a little Japanese. But I realize that my English is awful. So if I make any mistake, please tell me. This would improve my English and I will appreciate it.

I hope we can have a good summer in 2019. And have some good codes :)

Continuing with the addition of line terminating style for the Straight Line annotation tool, I have added the ability to select the line start style also. The required code changes are committed today.

Line annotation with circled start and closed arrow ending.

Currently it is supported only for PDF documents (and poppler version ≥ 0.72), but that will change soon — thanks to another change by Tobias Deiminger under review to extend the functionality for other documents supported by Okular.

• version 0.4.1
• Use only undeprecated KDEInstallDirs variables
• KDECMakeSettings already cares for CMAKE_AUTOMOC & BUILD_TESTING
• Fix use in cross compilation
• Q_ENUMS -> Q_ENUM
• more complete release instructions

by

Recently I have been researching into possibilities to make members of KoShape copy-on-write. At first glance, it seems enough to declare d-pointers as some subclass of QSharedDataPointer (see Qt’s implicit sharing) and then replace pointers with instances. However, there remain a number of problems to be solved, one of them being polymorphism.

polymorphism and value semantics

In the definition of KoShapePrivate class, the member fill is stored as a QSharedPointer:

QSharedPointer<KoShapeBackground> fill;

There are a number of subclasses of KoShapeBackground, including KoColorBackground, KoGradientBackground, to name just a few. We cannot store an instance of KoShapeBackground directly since we want polymorphism. But, well, making KoShapeBackground copy-on-write seems to have nothing to do with whether we store it as a pointer or instance. So let’s just put it here – I will come back to this question at the end of this post.

d-pointers and QSharedData

The KoShapeBackground heirarchy (similar to the KoShape one) uses derived d-pointersfor storing private data. To make things easier, I will here use a small example to elaborate on its use.

derived d-pointer

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50

class AbstractPrivate
{
public:
    AbstractPrivate() : var(0) {}
    virtual ~AbstractPrivate() = default;

    int var;
};

class Abstract
{
public:
    // it is not yet copy-constructable; we will come back to this later
    // Abstract(const Abstract &other) = default;
    ~Abstract() = default;
protected:
    explicit Abstract(AbstractPrivate &dd) : d_ptr(&dd) {}
public:
    virtual void foo() const = 0;
    virtual void modifyVar() = 0;
protected:
    QScopedPointer<AbstractPrivate> d_ptr;
private:
    Q_DECLARE_PRIVATE(Abstract)
};

class DerivedPrivate : public AbstractPrivate
{
public:
    DerivedPrivate() : AbstractPrivate(), bar(0) {}
    virtual ~DerivedPrivate() = default;

    int bar;
};

class Derived : public Abstract
{
public:
    Derived() : Abstract(*(new DerivedPrivate)) {}
    // it is not yet copy-constructable
    // Derived(const Derived &other) = default;
    ~Derived() = default;
protected:
    explicit Derived(AbstractPrivate &dd) : Abstract(dd) {}
public:
    void foo() const override { Q_D(const Derived); cout << "foo " << d->var << " " << d->bar << endl; }
    void modifyVar() override { Q_D(Derived); d->var++; d->bar++; }
private:
    Q_DECLARE_PRIVATE(Derived)
};

The main goal of making DerivedPrivate a subclass of AbstractPrivate is to avoid multiple d-pointers in the structure. Note that there are constructors taking a reference to the private data object. These are to make it possible for a Derived object to use the samed-pointer as its Abstract parent. The Q_D() macro is used to convert the d_ptr, which is a pointer to AbstractPrivate to another pointer, named d, of some of its descendent type; here, it is a DerivedPrivate. It is used together with the Q_DECLARE_PRIVATE() macro in the class definition and has a rather complicated implementation in the Qt headers. But for simplicity, it does not hurt for now to understand it as the following:

#define Q_D(Class) Class##Private *const d = reinterpret_cast<Class##Private *>(d_ptr.data())

where Class##Private means simply to append string Private to (the macro argument) Class.

Now let’s test it by creating a pointer to Abstract and give it a Derived object:

1
2
3
4
5
6
7

int main()
{
    QScopedPointer<Abstract> ins(new Derived());
    ins->foo();
    ins->modifyVar();
    ins->foo();
}

Output:

foo 0 0foo 1 1

Looks pretty viable – everything’s working well! – What if we use Qt’s implicit sharing? Just make AbstractPrivate a subclass of QSharedData and replace QScopedPointer with QSharedDataPointer.

making d-pointer QSharedDataPointer

In the last section, we commented out the copy constructors since QScopedPointer is not copy-constructable,but here QSharedDataPointer is copy-constructable, so we add them back:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48

class AbstractPrivate : public QSharedData
{
public:
    AbstractPrivate() : var(0) {}
    virtual ~AbstractPrivate() = default;

    int var;
};

class Abstract
{
public:
    Abstract(const Abstract &other) = default;
    ~Abstract() = default;
protected:
    explicit Abstract(AbstractPrivate &dd) : d_ptr(&dd) {}
public:
    virtual void foo() const = 0;
    virtual void modifyVar() = 0;
protected:
    QSharedDataPointer<AbstractPrivate> d_ptr;
private:
    Q_DECLARE_PRIVATE(Abstract)
};

class DerivedPrivate : public AbstractPrivate
{
public:
    DerivedPrivate() : AbstractPrivate(), bar(0) {}
    virtual ~DerivedPrivate() = default;

    int bar;
};

class Derived : public Abstract
{
public:
    Derived() : Abstract(*(new DerivedPrivate)) {}
    Derived(const Derived &other) = default;
    ~Derived() = default;
protected:
    explicit Derived(AbstractPrivate &dd) : Abstract(dd) {}
public:
    void foo() const override { Q_D(const Derived); cout << "foo " << d->var << " " << d->bar << endl; }
    void modifyVar() override { Q_D(Derived); d->var++; d->bar++; }
private:
    Q_DECLARE_PRIVATE(Derived)
};

And testing the copy-on-write mechanism:

1
2
3
4
5
6
7
8
9

int main()
{
    QScopedPointer<Derived> ins(new Derived());
    QScopedPointer<Derived> ins2(new Derived(*ins));
    ins->foo();
    ins->modifyVar();
    ins->foo();
    ins2->foo();
}

But, eh, it’s a compile-time error.

error: reinterpret_cast from type &aposconst AbstractPrivate*&apos to type &aposAbstractPrivate*&apos casts away qualifiers Q_DECLARE_PRIVATE(Abstract)

Q_D, revisited

So, where does the const removal come from? In qglobal.h, the code related to Q_D is as follows:

1
2
3
4
5
6
7
8
9
10
11
12
13

template <typename T> inline T *qGetPtrHelper(T *ptr) { return ptr; }
template <typename Ptr> inline auto qGetPtrHelper(const Ptr &ptr) -> decltype(ptr.operator->()) { return ptr.operator->(); }

// The body must be a statement:
#define Q_CAST_IGNORE_ALIGN(body) QT_WARNING_PUSH QT_WARNING_DISABLE_GCC("-Wcast-align") body QT_WARNING_POP
#define Q_DECLARE_PRIVATE(Class) \
    inline Class##Private* d_func() \
    { Q_CAST_IGNORE_ALIGN(return reinterpret_cast<Class##Private *>(qGetPtrHelper(d_ptr));) } \
    inline const Class##Private* d_func() const \
    { Q_CAST_IGNORE_ALIGN(return reinterpret_cast<const Class##Private *>(qGetPtrHelper(d_ptr));) } \
    friend class Class##Private;

#define Q_D(Class) Class##Private * const d = d_func()

It turns out that Q_D will call d_func() which then calls an overload of qGetPtrHelper() that takes const Ptr &ptr. What does ptr.operator->() return? What is the difference between QScopedPointer and QSharedDataPointer here?

QScopedPointer‘s operator->() is a const method that returns a non-const pointer to T; however, QSharedDataPointer has two operator->()s, one being const T* operator->() const, the other T* operator->(), and theyhave quite different behaviours – the non-const variant calls detach() (where copy-on-write is implemented), but the other one does not.

qGetPtrHelper() here can only take d_ptr as a const QSharedDataPointer, not a non-const one; so, no matter which d_func() we are calling, we can only get a const AbstractPrivate *. That is just the problem here.

To resolve this problem, let’s replace the Q_D macros with the ones we define ourselves:

#define CONST_SHARED_D(Class) const Class##Private *const d = reinterpret_cast<const Class##Private *>(d_ptr.constData())#define SHARED_D(Class) Class##Private *const d = reinterpret_cast<Class##Private *>(d_ptr.data())

We will then use SHARED_D(Class) in place of Q_D(Class) and CONST_SHARED_D(Class) for Q_D(const Class). Since the const and non-const variant really behaves differently, it should help to differentiate these two uses. Also, delete Q_DECLARE_PRIVATE since we do not need them any more:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44

class AbstractPrivate : public QSharedData
{
public:
    AbstractPrivate() : var(0) {}
    virtual ~AbstractPrivate() = default;

    int var;
};

class Abstract
{
public:
    Abstract(const Abstract &other) = default;
    ~Abstract() = default;
protected:
    explicit Abstract(AbstractPrivate &dd) : d_ptr(&dd) {}
public:
    virtual void foo() const = 0;
    virtual void modifyVar() = 0;
protected:
    QSharedDataPointer<AbstractPrivate> d_ptr;
};

class DerivedPrivate : public AbstractPrivate
{
public:
    DerivedPrivate() : AbstractPrivate(), bar(0) {}
    virtual ~DerivedPrivate() = default;

    int bar;
};

class Derived : public Abstract
{
public:
    Derived() : Abstract(*(new DerivedPrivate)) {}
    Derived(const Derived &other) = default;
    ~Derived() = default;
protected:
    explicit Derived(AbstractPrivate &dd) : Abstract(dd) {}
public:
    void foo() const override { CONST_SHARED_D(Derived); cout << "foo " << d->var << " " << d->bar << endl; }
    void modifyVar() override { SHARED_D(Derived); d->var++; d->bar++; }
};

With the same main() code, what’s the result?

foo 0 0foo 1 16606417foo 0 0

… big whoops, what is that random thing there? Well, if we use dynamic_cast in place of reinterpret_cast, the program simply crashes after ins->modifyVar();, indicating that ins‘s d_ptr.data() is not at all a DerivedPrivate.

virtual clones

The detach() method of QSharedDataPointer will by default create an instance of AbstractPrivate regardless of what the instance really is. Fortunately, it is possible to change that behaviour through specifying the clone() method.

First, we need to make a virtual function in AbstractPrivate class:

virtual AbstractPrivate *clone() const = 0;

(make it pure virtual just to force all subclasses to re-implement it; if your base class is not abstract you probably want to implement the clone() method) and then override it in DerivedPrivate:

virtual DerivedPrivate *clone() const { return new DerivedPrivate(*this); }

Then, specify the template method for QSharedDataPointer::clone(). As we will re-use it multipletimes (for different base classes), it is better to define a macro:

1
2
3
4
5
6
7

#define DATA_CLONE_VIRTUAL(Class) template<>                      \
    Class##Private *QSharedDataPointer<Class##Private>::clone()   \
    {                                                             \
        return d->clone();                                        \
    }
// after the definition of Abstract
DATA_CLONE_VIRTUAL(Abstract)

It is not necessary to write DATA_CLONE_VIRTUAL(Derived) as we are never storing a QSharedDataPointer<DerivedPrivate> throughout the heirarchy.

Then test the code again:

foo 0 0foo 1 1foo 0 0

– Just as expected! It continues to work if we replace Derived with Abstract in QScopedPointer:

QScopedPointer<Abstract> ins(new Derived());QScopedPointer<Abstract> ins2(new Derived(* dynamic_cast<const Derived *>(ins.data())));

Well, another problem comes, that the constructor for ins2 seems too ugly, and messy. We could, like the private classes, implement a virtual function clone() for these kinds of things, but it is still not gentle enough, and we cannot use a default copy constructor for any class that contains such QScopedPointers.

What about QSharedPointer that is copy-constructable? Well, then these copies actually point to the same data structures and no copy-on-write is performed at all. This still not wanted.

the Descendents of …

Inspired by Sean Parent’s video, I finally come up with the following implementation:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

template<typename T>
class Descendent
{
    struct concept
    {
        virtual ~concept() = default;
        virtual const T *ptr() const = 0;
        virtual T *ptr() = 0;
        virtual unique_ptr<concept> clone() const = 0;
    };
    template<typename U>
    struct model : public concept
    {
        model(U x) : instance(move(x)) {}
        const T *ptr() const { return &instance; }
        T *ptr() { return &instance; }
        // or unique_ptr<model<U> >(new model<U>(U(instance))) if you do not have C++14
        unique_ptr<concept> clone() const { return make_unique<model<U> >(U(instance)); }
        U instance;
    };

    unique_ptr<concept> m_d;
public:
    template<typename U>
    Descendent(U x) : m_d(make_unique<model<U> >(move(x))) {}

    Descendent(const Descendent & that) : m_d(move(that.m_d->clone())) {}
    Descendent(Descendent && that) : m_d(move(that.m_d)) {}

    Descendent & operator=(const Descendent &that) { Descendent t(that); *this = move(t); return *this; }
    Descendent & operator=(Descendent && that) { m_d = move(that.m_d); return *this; }

    const T *data() const { return m_d->ptr(); }
    const T *constData() const { return m_d->ptr(); }
    T *data() { return m_d->ptr(); }
    const T *operator->() const { return m_d->ptr(); }
    T *operator->() { return m_d->ptr(); }
};

This class allows you to use Descendent<T> (read as “descendent of T“) to represent any instance of any subclass of T. It is copy-constructable, move-constructable, copy-assignable, and move-assignable.

Test code:

1
2
3
4
5
6
7
8
9

int main()
{
    Descendent<Abstract> ins = Derived();
    Descendent<Abstract> ins2 = ins;
    ins->foo();
    ins->modifyVar();
    ins->foo();
    ins2->foo();
}

It gives just the same results as before, but much neater and nicer – How does it work?

First we define a class concept. We put here what we want our instance to satisfy. We would like to access it as const and non-const, and to clone it as-is. Then we define a template class model<U> where U is a subclass of T, and implement these functionalities.

Next, we store a unique_ptr<concept>. The reason for not using QScopedPointer is QScopedPointer is not movable, but movability is a feature we actually will want (in sink arguments and return values).

Finally it’s just the constructor, moving and copying operations, and ways to access the wrapped object.

When Descendent<Abstract> ins2 = ins; is called, we will go through the copy constructor of Descendent:

Descendent(const Descendent & that) : m_d(move(that.m_d->clone())) {}

which will then call ins.m_d->clone(). But remember that ins.m_d actually contains a pointer to model<Derived>, whose clone() is return make_unique<model<Derived> >(Derived(instance));. This expression will call the copy constructor of Derived, then make a unique_ptr<model<Derived> >, which calls the constructor of model<Derived>:

model(Derived x) : instance(move(x)) {}

which move-constructs instance. Finally the unique_ptr<model<Derived> > is implicitly converted to unique_ptr<concept>, as per the conversion rule. “If T is a derived class of some base B, then std::unique_ptr<T> is implicitly convertible to std::unique_ptr<B>.”

And from now on, happy hacking — (.>w<.)

Hot on the heels of last week, this week’s Usability & Productivity report continues to overflow with awesomeness. Quite a lot of work what you see featured here is already available to test out in the Plasma 5.16 beta, too! But why stop? Here’s more:

New Features

• We now have full support for configuring touchpads using the Libinput driver on X11, including enabling or disabling horizontal scrolling (Atul Bisht, KDE Plasma 5.16.0)
• Plasma’s OpenConnect network plugin gained support for the GlobalProtect protocol in OpenConnect (Alejandro Valdes, KDE Plasma 5.16.0)
• In open/save dialogs, it’s now possible to drag-and-drop files to the main file list view to have the dialog quickly select that file (Méven Car, KDE Frameworks 5.59)
• Dolphin now has a bookmarks management system for people with way more frequently-accessed locations than can be easily managed with the Places panel (David Hallas, Dolphin 19.08.0):

  Clearly I am not one of those people

Bugfixes & Performance Improvements

• Lots of bugfixes for the notification rewrite in Plasma 5.16: pop-ups are located correctly in multi-screen environments (Daniel Vrátil) and when using a vertical panel (Kai Uwe Broulik); the System Tray window closes when un-hiding a pop-up (Kai Uwe Broulik). And there’s more to come, too!
• The SDDM login screen theme downloader no longer crashes if you cancel out of the password dialog or decline to enter your password within 30 seconds (John Gehrig, KDE Plasma 5.16.0)
• Discover’s Featured page now displays ratings as soon as they’re loaded, rather than making you navigate away from it and then back again (Aleix Pol Gonzalez, KDE Plasma 5.16.0)
• On Wayland, it’s now possible to resize GTK headerbar windows from window edges (David Edmundson, KDE Plasma 5.17.0)
• Pushed a fix for crashing QML apps on the unreleased Frameworks 5.59, which was biting Neon Dev Unstable users. This crash was traced to a Qt issue, but only recently recently exposed by the recent bugfix for horizontal scrollbar handle size calculation. Software is complex, man! (Marco Martin, KDE Frameworks 5.59)
• It’s now possible to drag-and-drop links that are more than 256 characters long from web browsers to the desktop (Chinmoy Ranjan Pradhan, KDE Framrworks 5.59)
• The Baloo file indexing system now ignores SQL database dumps, files relating to virtual machine disks, and 3D printing .gcode files (me: Nate Graham, KDE Frameworks 5.59)
• Dolphin no longer crashes when hiding a device in the Places Panel’s Devices category (David Hallas, Dolphin 19.08.0)
• Gwenview now displays vastly more EXIF metadata for RAW images (Tom Moebert, Gwenview 19.08.0)

User Interface Improvements

• Discover’s sidebar now looks like a regular desktop-style sidebar (me: Nate Graham, KDE Plasma 5.16.0):
  
• All Plasma widgets’ configuration windows have been thoroughly modernized in design and technology, now using a centered style and the latest Qt and Kirigami APIs (me: Nate Graham, Filip Fila, Björn Feber, and Krešimir Čohar, KDE Plasma 5.16.0):
  
  
  
  
• Buttons in the login, lock, and logout screens now have a little animation when clicked (Filip Fila, KDE Plasma 5.16.0):
  
• Dolphin’s Samba share creation interface now has more comprehensible wording, displays the correct status while installing, and the user interface controls properly enable and disable themselves depending on whether the folder is shared (me: Nate Graham, KDE Applications 19.04.2):
  
• When using inline renaming on a file in Dolphin, the Home and End keys now always jump to the beginning or end of the whole filename, rather than the beginning or end of the current line (Chinmoy Ranjan Pradhan, Dolphin 19.08.0)

Next week, your name could be in this list! Not sure how? Just ask! I’ve helped mentor a number of new contributors recently and I’d love to help you, too! You can also check out https://community.kde.org/Get_Involved, and find out how you can help be a part of something that really matters. You don’t have to already be a programmer. I wasn’t when I got started. Try it, you’ll like it! We don’t bite!

If you find KDE software useful, consider making a donation to the KDE e.V. foundation.

Hi! I’m Akhil K Gangadharan and I’ve been selected for GSoC this year with Kdenlive. My project is titled ‘Revamping the Titler Tool’ and my work for this summer aims to kickoff the complete revamp of one of the major tools used in video-editing in Kdenlive, called the Titler tool.

Titler Tool?

The Titler tool is used to create, you guessed it, title clips. Title clips are clips that contain text and images that can be composited over videos.

The Titler tool

Why revamp it?

In Kdenlive, the titler tool is implemented using QGraphicsView which is considered deprecated since the release of Qt5. This makes it obviously prone to bugs that may appear in the upstream to affect the functionality of the tool. This has caused issues in the past, popular features like the Typewriter effect had to be dropped because of QGraphicsView which lead to uncontrollable crashes.

How?

Using QML.

Currently the Titler Tool uses QPainter, which paints every property and every animation is required to be programmed. QML allows creating powerful animations easily as QML as a language is designed for designing UI, which can be then rendered to create title clips as per our need.

Implementation details - a brief overview

For the summer, I intend to complete work on the backend implementation. The first step is to write and test a complete MLT producer module which can render QML frames. And then to begin test integration of this module with a new titler tool.

This is how the backend currently looks like -

After the revamp, the backend would look like -

After the backend is done with, we begin integrating it with Kdenlive and evolve the titler to use the new backend.

A great long challenge lies ahead, and I’m looking forward to this summer and beyond with the community to complete writing the tool - right from the backend to the new UI.

Finally, a big thanks to the Kdenlive community for getting me here and to my college student community, FOSS@Amrita for all the support and love!

Thanks to Nick Richards we've been able to convince flathub to momentarily accept our old appdata files as still valid, it's a stopgap workaround, but at least gives us some breathing time. So the updates are coming in as we speak.

I was accepted to Google Summer of Code. I will work with Krita implementing an Animated Vector Brush Read more...

It’s been a great pleasure to be chosen to work with KDE during GSoC this year. I’ll be working on KIOFuse and hopefully by the end of the coding period it will be well integrated with KIO itself. Development will mainly by coordinated on the #kde-fm channel (IRC Nick: feverfew) with fortnightly updates on my blog so feel free to pop by! Here’s a small snippet of my proposal to give everyone an idea of what I’ll be working on:

KIOSlaves are a powerful feature within the KIO framework, allowing KIO-aware applications
such as Dolphin to interact with services out of the local filesystem over URLs such as fish://
and gdrive:/. However, KIO-unaware applications are unable to interact seamlessly with KIO
Slaves. For example, editing a file in gdrive:/ in LibreOffice will not save changes to your Google Drive. One potential solution is to make use of FUSE, which is an interface provided
by the Linux kernel, which allows userspace processes to provide a filesystem which can be
mounted and accessed by regular applications. ​KIOFuse is a project by fvogt that
allows the possibility to mount KIO filesystems in the local system; therefore exposing them to
POSIX-compliant applications such as Firefox and LibreOffice.

This project intends to polish KIOFuse such that it is ready to be a KDE project. In particular,
I’ll be focusing on the following four broad goals:
• ​Improving compatibility with KDE and non-KDE applications by extending and improving
supported filesystem operations.
• ​Improving KIO Slave support.
• ​Performance and usability improvements.
• ​Adding a KDE Daemon module to allow the management of KIOFuse mounts and the
translation of KIO URLs to their local path equivalents.

The flatpak and flathub developers have changed what they consider a valid appdata file, so our appdata files that were valid last month are not valid anymore and thus we can't build the KDE Applications 19.04.1 packages.

Help testing the Plasma Theme switching now

You like Plasma Themes? You design Plasma Themes even yourself? You want to see switching Plasma Themes working correctly, especially for Plasma panels?

Please get one of the Live images with latest code from the Plasma developers hands (or if you build manually yourself from master branches, last night’s code should be fine) and give the switching of Plasma Themes a good test, so we can be sure things will work as expected on arrival of Plasma 5.16:

• KDE neon Unstable Edition
• openSUSE Krypton

If you find glitches, please report them here in the comments, or better on the #plasma IRC channel.

Plasma Themes, to make it more your Plasma

One of the things which makes Plasma so attractive is the officially supported option to customize also the style, and that beyond colors and wallpaper, to allow users to personalize the look to their likes. And designers have picked up on that and did a good set of custom designs (store.kde.org lists at the time of writing 470 themes).

And while in the last Plasma versions some regressions in the Theme support had sneaked in, because most people & developers are happily using the default Breeze theme, with Plasma 5.16 some theming fixes are to arrive.

Plasma Theme looking good on first contact with Plasma 5.16

The most annoying pain point has been that on selecting and applying a new Plasma Theme, the theme data was not correctly picked up especially by Plasma panels. Only after a restart of Plasma could the theme be fully experienced. Which made quick testing of themes e.g. from store.kde.org a sad story, given most themes looked a bit broken. And without knowing more one would think it is the theme’s fault.

But some evenings & nights have been spent to hunt down the reasons, and it seems they all have been found and corrected. So when one clicks the “Apply” button, the Plasma Theme instantly styles your Plasma desktop as it should, especially the panels.

And dressing up your desktop to match your day or week or mood or your shirt with one of those partially excellent themes is only a matter of some mouse clicks. No more restart needed

Coming to your system with Plasma 5.16 and KDE Frameworks 5.59 (both to be released in June).

Make your Plasma Theme take advantage of Plasma 5.16

Theme designers, please study the recently added page on techbase.kde.org about Porting Themes to latest Plasma 5. It lists the changes known so far and what to do for them. Please extend the list if something is yet missing.
And tell your theme designer friends about this page, so they can improve their themes as well.