In this post, I am going to discuss about the working of a submarine and my thought process on implementing the three basic features of a submarine in the “Pilot a Submarine” activity for the Qt version of GCompris, which are:

• The Engine
• The Ballast tanks and
• The Diving Planes

The Engine

The engine of most submarines are either nuclear powered or diesel-electric engines, which are used to drive an electric motor which in turn, powers the submarine propellers. In this implementation, we will have two buttons one for increasing and another for decreasing the power generated by the submarine.

Ballast Tanks

The Ballast Tanks are the spaces in the submarine that can either be filled with water or air. It helps the submarine to dive and resurface on the water, using the concept of buouyancy. If the tanks are filled with water, the submarine dives underwater and if they are filled with air, it resurfaces on the surface of the water

Diving Planes

Once underwater, the diving planes of a submarine helps to accurately control the depth of the submarine. These are very similar to the fins present in the bodies of sharks, which helps them to swim and dive. When the planes are pointed downwards, the water flowing above the planes generate more pressure on the top surface than that on the bottom surface, forcing the submarine to dive deeper. This allows the driver to control the depth and the angle of the submarine.

Implementation

In this section I will be going through how I implemented the submarine using QML. For handling physics, I used Box2D.

The Submarine

The submarine is an QML Item element, designed as follows:

Item {
    id: submarine

    z: 1

    property point initialPosition: Qt.point(0,0)
    property bool isHit: false
    property int terminalVelocityIndex: 100
    property int resetVerticalSpeed: 500

    /* Maximum depth the submarine can dive when ballast tank is full */
    property real maximumDepthOnFullTanks: (background.height * 0.6) / 2

    /* Engine properties */
    property point velocity
    property int maximumXVelocity: 5

    /* Wings property */
    property int wingsAngle
    property int initialWingsAngle: 0
    property int maxWingsAngle: 2
    property int minWingsAngle: -2

    function destroySubmarine() {
        isHit = true
        submarineImage.broken()
    }

    function resetSubmarine() {
        isHit = false
        submarineImage.reset()

        leftBallastTank.resetBallastTanks()
        rightBallastTank.resetBallastTanks()
        centralBallastTank.resetBallastTanks()

        x = initialPosition.x
        y = initialPosition.y

        velocity = Qt.point(0,0)
        wingsAngle = initialWingsAngle
    }

	function increaseHorizontalVelocity(amt) {
        if (submarine.velocity.x + amt <= submarine.maximumXVelocity) {
            submarine.velocity.x += amt
        }
    }

    function decreaseHorizontalVelocity(amt) {
        if (submarine.velocity.x - amt >= 0) {
            submarine.velocity.x -= amt
        }
    }

    function increaseWingsAngle(amt) {
        if (wingsAngle + amt <= maxWingsAngle) {
            wingsAngle += amt
        } else {
            wingsAngle = maxWingsAngle
        }
    }

    function decreaseWingsAngle(amt) {
        if (wingsAngle - amt >= minWingsAngle) {
            wingsAngle -= amt
        } else {
            wingsAngle = minWingsAngle
        }
    }

    function changeVerticalVelocity() {
        /*
         * Movement due to planes
         * Movement is affected only when the submarine is moving forward
         * When the submarine is on the surface, the planes cannot be used
         */
        if (submarineImage.y > 0) {
            submarine.velocity.y = (submarine.velocity.x) > 0 ? wingsAngle : 0
        } else {
            submarine.velocity.y = 0
        }
        /* Movement due to Ballast tanks */
        if (wingsAngle == 0 || submarine.velocity.x == 0) {
            var yPosition = submarineImage.currentWaterLevel / submarineImage.totalWaterLevel * submarine.maximumDepthOnFullTanks

            speed.duration = submarine.terminalVelocityIndex * Math.abs(submarineImage.y - yPosition) // terminal velocity
            submarineImage.y = yPosition
        }
    }

    BallastTank {
        id: leftBallastTank

        initialWaterLevel: 0
        maxWaterLevel: 500
    }

    BallastTank {
        id: rightBallastTank

        initialWaterLevel: 0
        maxWaterLevel: 500
    }

    BallastTank {
        id: centralBallastTank

        initialWaterLevel: 0
        maxWaterLevel: 500
    }

    Image {
        id: submarineImage
        source: url + "submarine.png"

        property int currentWaterLevel: bar.level < 7 ? centralBallastTank.waterLevel : leftBallastTank.waterLevel + centralBallastTank.waterLevel + rightBallastTank.waterLevel
        property int totalWaterLevel: bar.level < 7 ? centralBallastTank.maxWaterLevel : leftBallastTank.maxWaterLevel + centralBallastTank.maxWaterLevel + rightBallastTank.maxWaterLevel

        width: background.width / 9
        height: background.height / 9

        function broken() {
            source = url + "submarine-broken.png"
        }

        function reset() {
            source = url + "submarine.png"
            speed.duration = submarine.resetVerticalSpeed
            x = submarine.initialPosition.x
            y = submarine.initialPosition.y
        }

        Behavior on y {
            NumberAnimation {
                id: speed
                duration: 500
            }
        }

        onXChanged: {
            if (submarineImage.x >= background.width) {
                Activity.finishLevel(true)
            }
        }
    }

    Body {
        id: submarineBody
        target: submarineImage
        bodyType: Body.Dynamic
        fixedRotation: true
        linearDamping: 0
        linearVelocity: submarine.isHit ? Qt.point(0,0) : submarine.velocity

        fixtures: Box {
            id: submarineFixer
            width: submarineImage.width
            height: submarineImage.height
            categories: items.submarineCategory
            collidesWith: Fixture.All
            density: 1
            friction: 0
            restitution: 0
            onBeginContact: {
                var collidedObject = other.getBody().target

                if (collidedObject == whale) {
                    whale.hit()
                }
                if (collidedObject == crown) {
                    crown.captureCrown()
                } else {
                    Activity.finishLevel(false)
                }
            }
        }
    }
    Timer {
        id: updateVerticalVelocity
        interval: 50
        running: true
        repeat: true

        onTriggered: submarine.changeVerticalVelocity()
    }
}

The Item is a parent object to hold all the different components of the submarine (the Image BallastTank and the Box2D component). It also contains the functions and the variables that are global to the submarine.

The Engine

The engine is a very straightforward implementation via the linearVelocity component of the Box2D element. We have two variables global to the submarine for handling the engine component, defined as follows:

property point velocity
property int maximumXVelocity: 5

which are pretty much self-explanatory, the velocity holds the current velocity of the submarine, both horizontal and vertical and the maximumXVelocity holds the maximum horizontal speed the submarine can achieve.

For increasing or decreasing the velocity of the submarine, we have two functions global to the submarine, as follows:

function increaseHorizontalVelocity(amt) {
    if (submarine.velocity.x + amt <= submarine.maximumXVelocity) {
        submarine.velocity.x += amt
    }
}

function decreaseHorizontalVelocity(amt) {
    if (submarine.velocity.x - amt >= 0) {
        submarine.velocity.x -= amt
    }
}

which essentially gets the amount by which the velocity.x component needs to be increased or decreased, checks whether it crosses the range or not, and makes the necessary changes likewise.

The actual applying of the velocity is very straightforward, which takes place in the Body component of the submarine as follows:

Body {
	...
	linearVelocity: submarine.isHit ? Qt.point(0,0) : submarine.velocity
	...

The submarine.isHit component, as the name suggests holds whether the submarine is hit by any object or not (except the pickups). If so, the velocity is reset to (0,0)

Thus, for increasing or decreasing the engine power, we just have to call one of the two functions anywhere from the code:

submarine.increaseHorizontalVelocity(1); /* For increasing H velocity */
submarine.decreaseHorizontalVelocity(1); /* For decreasing H velocity */

The Ballast Tanks

The Ballast Tanks are implemented separately in BallastTank.qml, since it will be implemented more that once. It looks like the following:

Item {
    property int initialWaterLevel
    property int waterLevel: 0
    property int maxWaterLevel
    property int waterRate: 10
    property bool waterFilling: false
    property bool waterFlushing: false

    function fillBallastTanks() {
        waterFilling = !waterFilling

        if (waterFilling) {
            fillBallastTanks.start()
        } else {
            fillBallastTanks.stop()
        }
    }

    function flushBallastTanks() {
        waterFlushing = !waterFlushing

        if (waterFlushing) {
            flushBallastTanks.start()
        } else {
            flushBallastTanks.stop()
        }
    }

    function updateWaterLevel(isInflow) {
        if (isInflow) {
            if (waterLevel < maxWaterLevel) {
                waterLevel += waterRate

            }
        } else {
            if (waterLevel > 0) {
                waterLevel -= waterRate
            }
        }

        if (waterLevel > maxWaterLevel) {
            waterLevel = maxWaterLevel
        }

        if (waterLevel < 0) {
            waterLevel = 0
        }
    }

    function resetBallastTanks() {
        waterFilling = false
        waterFlushing = false

        waterLevel = initialWaterLevel

        fillBallastTanks.stop()
        flushBallastTanks.stop()
    }

    Timer {
        id: fillBallastTanks
        interval: 500
        running: false
        repeat: true

        onTriggered: updateWaterLevel(true)
    }

    Timer {
        id: flushBallastTanks
        interval: 500
        running: false
        repeat: true

        onTriggered: updateWaterLevel(false)
    }
}

What they essentially does is:

• fillBallastTanks: Fills up the Ballast tanks upto maxWaterLevel. Sets the flag waterFilling to true if the Ballast is to be filled with water, and the timer fillBallastTanks is set to start(), which will increase the water level in the tank after every 500 millisecond.
• flushBallastTanks: Flushes the Ballast tanks down to 0. Sets the flag waterFlushing to true if the Ballast is to be flushed out of water, and the timer flushBallastTanks is set to start(), which will decrease the water level in the tank after every 500 millisecond.
• resetBallastTanks: Resets the water level in the ballast tanks to it’s initial values

In the Submarine Item, we just use three instances of the BallastTank object, for left, right and central ballast tanks, setting up it’s initial and maximum water level.

BallastTank {
    id: leftBallastTank

    initialWaterLevel: 0
    maxWaterLevel: 500
}

BallastTank {
    id: rightBallastTank

    initialWaterLevel: 0
    maxWaterLevel: 500
}

BallastTank {
    id: centralBallastTank

    initialWaterLevel: 0
    maxWaterLevel: 500
}

For filling up or flushing the ballast tanks (centralBallastTank in this case), we just have two call either of the following two functions:

centralBallastTank.fillBallastTanks() /* For filling */
centralBallastTank.flushBallastTanks() /* For flushing */

I will be discussing about how the depth is maintained using the ballast tanks in the next section.

The Diving Planes

The diving planes will be used to control the depth of the submarine once it is moving underwater. Keeping that in mind, along with the fact that it needs to be effectively integrated with the ballast tanks. This is implemented in the changeVerticalVelocity() function, which is discussed as follows:

/*
 * Movement due to planes
 * Movement is affected only when the submarine is moving forward
 * When the submarine is on the surface, the planes cannot be used
 */
if (submarineImage.y > 0) {
    submarine.velocity.y = (submarine.velocity.x) > 0 ? wingsAngle : 0
} else {
    submarine.velocity.y = 0
}

However, under the following conditions:

• the angle of the planes is reduced to 0
• the horizontal velocity of the submarine is 0,

the ballast tanks will take over. Which is implemented as:

/* Movement due to Ballast tanks */
if (wingsAngle == 0 || submarine.velocity.x == 0) {
    var yPosition = submarineImage.currentWaterLevel / submarineImage.totalWaterLevel * submarine.maximumDepthOnFullTanks

    speed.duration = submarine.terminalVelocityIndex * Math.abs(submarineImage.y - yPosition) // terminal velocity
    submarineImage.y = yPosition
}

yPosition calculates how much percentage of the tank is filled with water, and likewise it determines the depth to which it will dive. The speed.duration is the duration of the transition animation, and the duration depends directly on how much the submarine will have to cover up along the Y axis, to avoid a steep rise or fall of the submarine.

For increasing or decreasing the angle of the diving planes, we just need to call either of the following two functions:

submarine.increaseWinglsAngle(1) /* For increasing */
submarine.decreaseWingsAngle(1) /* For decerasing */

That’s it for now! The two major goals to be completed next are the rotation of the submarine (in case more than one tanks are used and they are unequally filled up) and the UI for controlling the submarine. Will provide an update on it once it is completed.

It is a long time since I posted on my blog and frankly, i missed it. I’ve been busy with school: courses, tones of homework, projects and presentations.

Since last year i had a great experience with GCompris and KDE in general, i decided to apply in this year’s GSoC as well, only this time, i chose another project from KDE: Minuet.

Minuet is part of KDE-edu and its goal is helping teachers and students both novice and experienced teach and respectively learn and exercise their music skills. It is primarily focused on ear-training exercises and other areas will soon be available.

Minuet includes a virtual piano keyboard, displayed at the bottom of the screen, on which users can visualize the exercises. Using a piano keyboard is a good starting point for anyone who wants to learn the basics of musical theory: intervals, chords, scales etc. Minuet is currently based on the piano keyboard for all its ear training exercises. While this is a great feature, some may find it not quite suitable to their musical instrument.

My project aims to deliver to the user a framework which will support the implementation of multiple instrument views as Minuet plugins. Furthermore, apart from the piano keyboard, I will implement another instrument for playing the exercise questions and user’s answers.

This mechanism should allow new instruments to be integrated as Minuet plugins. After downloading the preferred instrument plugin, the user would then be able to switch between instruments. It will allow him to enhance his musical knowledge by training his skills using that particular instrument.

At the end of summer, I intend to have changed the current architecture to allow multiple-instrument visualization framework and refactor the piano keyboard view as a separate plugin. I also intend to have implemented a plugin for at least one new instrument: a guitar.

A mock up on the new guitar is shown below:

I hope it will be a great summer for me, my mentor and the users of Minuet, whom i want to offer a better experience by using my work.

Sounds like déjà vu? You are right! We used to have Facebook Event sync in KOrganizer back in KDE 4 days thanks to Martin Klapetek. The Facebook Akonadi resource, unfortunately, did not survive through Facebook API changes and our switch to KF5/Qt5.

I’m using a Facebook event sync app on my Android phone, which is very convenient as I get to see all events I am attending, interested in or just invited to directly in my phone’s calendar and I can schedule my other events with those in mind. Now I finally grew tired of having to check my phone or Facebook whenever I wanted to schedule event through KOrganizer and I spent a few evenings writing a brand new Facebook Event resource.

Inspired by the Android app the new resource creates several calendars – for events you are attending, events you are interested in, events you have declined and invitations you have not responded to yet. You can configure if you want to receive reminders for each of those.

Additionally, the resource fetches a list of all your friend’s birthdays (at least of those who have their birthday visible to their friends) and puts them into a Birthday calendar. You can also configure reminders for those separately.

The Facebook Sync resource will be available in the next KDE Applications feature release in August.

Hello readers

I’m glad to share this opportunity to be selected 2 times for Google Summer of Code project under KDE. It’s my second consecutive year working with DigiKam team.

DigiKam is an advanced digital photo management  application which enables user to view, manage, edit, organise, tag and share photographs under Linux systems. DigiKam has a feature to search items by similarity. This require to compute image fingerprints stored in main database. These data can take space on disk especially with huge collection and bloat the main database a lots and increase complexity to backup main database which include all main information for each item registered, as tags, label, comments, etc.

The goal of this proposal is to store the similarity fingerprints must be stored in a dedicated database. This would be a big relief for the end users as image fingerprints are around few KB of raw data for each image. And storing all of them takes huge disk space, increases time latency for huge collections.

Thus, to overcome all the above issues, a new DB interface would be created. {This work has already been done for thumbnail and face fingerprints}. Also, from backup point of view, it’s easy to have separate files to optimise.

I’ll add keep you guys updated with my work in upcoming posts.

Till then, I encourage you to use the software. It’s easy to install and use. (You can find cheat sheet to build DigiKam in my previous post! )

Happy DigiKaming!

Following the 5th release 5.5.0 published in March 2017, the digiKam team is proud to announce the new release 5.6.0 of digiKam Software Collection. With this version the HTML gallery and the video slideshow tools are back, database shrinking (e.g. purging stale thumbnails) is also supported on MySQL, grouping items feature has been improved, the support for custom sidecars type-mime have been added, the geolocation bookmarks introduce fixes to be fully functional with bundles, the support for custom sidecars, and of course a lots of bug has been fixed.

HTML Gallery Tool

The HTML gallery is accessible through the tools menu in the main bar of both digiKam and showFoto. It allows you to create a a web gallery with a selection of photos or a set of albums, that you can open in any web browser. There are many themes to select and you can create your own as well. Javascript support is also available.

Video Slideshow Tool

The Video Slideshow is accessible also through the tools menu in the main bar of both digiKam and showFoto. It allows you to create a video slide with a selection of photos or albums. The generated video file can be view in any media player, as phones, tablets, Blue Ray reader, etc. There are many settings to customize the format, the codec, the resolution, and the transition (as for ex the famous Kens-Burn effect).

Database Integrity Tool

Already in 5.5.0 release, the tool dedicated to tests for database integrity and obsolete information have been improved. Besides obvious data safety improvements this can free up quite a lot of space in the digiKam databases. For technical reasons only SQLite database were shrunk to this smaller size in 5.5.0 release. Now this is also possible for MySQL databases with 5.6.0.

Items Grouping Features

Earlier changes to the grouping behaviour proved that digiKam users have quite diverse workflows - so with the current change we try to represent that diversity.

Originally grouped items were basically hidden away. Due to requests to include grouped items in certain operations, this was changed entirely to include grouped items in (almost) all operations. Needless to say, this wasn’t such a good idea either. So now you can choose which operations should be performed on all images in a group or just the first one.

The corresponding settings live in the configuration wizard under Miscellaneous in the Grouping tab. By default all operations are set to Ask, which will open a dialog whenever you perform this operation and grouped items are involved.

Extra Sidecars Support

Another new capability is to recognise additional sidecars. Under the new Sidecars tab in the Metadata part of the configuration wizard you can specify any additional extension that you want digiKam to recognise as a sidecar. These files will neither be read from nor written to, but they will be moved/rename/deleted/… together with the item that they belong to.

Geolocation Bookmarks

Another important change done for this new version is to restore the geolocation bookmarks feature which did not work with bundle versions of digiKam (AppImage, MacOS, and Windows). The new bookmarker has been fully re-written and is still compatible with previous geolocation bookmarks settings. It is now able to display the bookmark GPS information over a map for a better usability while editing your collection.

Google Summer of Code 2017 Students

This summer the team is proud to assist 4 students to work on separate projects:

Swati Lodha is back in the team. As in 2016, she will work to improve the Database interface. After having fixed and improved the MySQL support in digiKam, she has the task this year to isolate all the database contents dedicated to manage the similarity finger-prints matrix. As for thumbnails and face recognition, these elements will be stored in a new dedicated database. The goal is to reduce the core database size, simplify the maintenance and decrease the core database time-latencies.

Yingjie Liu is a Chinese student, mainly specialized with math and algorithms who will add a new efficient face recognition algorithm and will try to introduce some AI solution to simplify the face tag workflow.

Ahmed Fathi is an Egyptian student who will work to restore and improve the DLNA support in digiKam, to be able to stream collections contents through the network with compatible UPNP device as the Smart TV, tablets or cellulars.

Shaza Ismail is an another Egyptian student who will work to an ambitious project to create a tool for image editor to be used for healing image stains with the use of another part of the image by coloring by the use of one part over the other, mainly testing on dust spots, but can be used for other particles hiding as well.

Final Words

The next main digiKam version 6.0.0 is planned for the end of this year, when all Google Summer of Code projects will be ready to be backported for a beta release. In September, we will release a maintenance version 5.7.0 with a set of bugfixes as usual.

For further information about 5.6.0, take a look at the list of more than 81 issues closed in Bugzilla.

digiKam 5.6.0 Software collection source code tarball, Linux 32/64 bits AppImage bundles, MacOS package, and Windows 32/64 bits installers can be downloaded from this repository.

Happy digiKaming while this summer!

Set up the arcanist for Koko

• It was pretty much easy to install. For my Archlinux just below command did the work for me.

  yaourt -S arcanist-git

• Then I had to add .arcconfig to the Koko repository so that arc could point to the link where it should publish the changes

  { “phabricator.uri”:”https://phabricator.kde.org/” }

• The only problem is with the SSL certificates, as the university campus wireless network uses its own self-signed certificate. This will create problem to access the ssl encrypted web content, pretty much everything related to development :P
• Also university campus network does not allow SSH over it’s network. This will prohibit me from committing the changes to the git repository.
• Hence to use the arcanist, everytime I will have to check for the curl.cainfo in the /etc/php/php.ini and set/unset the environment variable GIT_SSL_CAINFO depending on the network I am using.

KRuler, in case you don't know it, is a simple software ruler to measure lengths on your desktop. It is one of the oldest KDE tools, its first commit dating from November 4th, 2000. Yes, it's almost old enough to vote.

I am a long time KRuler user. It gets the job done, but I have often found myself saying "one day I'll fix this or that". And never doing it.

Hidpi screen really hurt the poor app, so I finally decided to do something and spend some time during my daily commute on it.

This is what it looked like on my screen when I started working on it:

As any developer would, I expected it should not be more than a week of work... Of course it took way longer than that, because there was always something odd here and there, preventing me from pushing a patch.

I started by making KRuler draw scale numbers less often to avoid ugly overlapping texts. I then made it draw ticks on both sides, to go from 4 orientations (North, South, West, East) to 2: vertical or horizontal.

The optional rotation and buttons were getting in the way though: the symmetric ticks required the scale numbers to be vertically centered so buttons were overlapping it. I decided to remove them (they were already off by default). With only two orientations it is less useful to have rotation buttons anyway: it is simple enough to use either the context menu, middle-click the ruler, or the R shortcut to change the orientation. Closing is accessible through the context menu as well.

One of the reasons (I think) for the 4 orientations was the color picker feature. It makes little sense to me to have a color picker in a ruler: it is more natural to use KColorChooser to pick colors. I removed the color picker, allowing me to remove the oddly shaped mouse cursor and refresh the appearance of the length indicator to something a bit nicer.

I then made it easier to adjust the length of the ruler by dragging its edges instead of having to pick the appropriate length from a sub-menu of the context menu. This made it possible to remove this sub-menu.

This is what KRuler looks like now:

That is only part 1 though. I originally had 2 smaller patches to add, but Jonathan Riddell, who kindly reviewed the monster patch, requested another small fix, so that makes 3 patches to go. Need to setup and figure out how to use Arcanist to submit them to Phabricator, as I have been told Review Board is old school these days :)

Or: Tying loose ends where some are slightly too short yet.

When

• you favour offline documentation (not only due to nice integration with IDEs like KDevelop),
• develop code using KDE Frameworks or other Qt-based libraries,
• you know all the KF5 libraries have seen many people taking care for API documentation in the code over all the years,
• and you had read about doxygen’s capability to create API dox in QCH format,
• and you want your Linux distribution package management to automatically deliver the latest version of the documentation (resp. QCH files) together with the KDE Frameworks libraries and headers (and ideally same for other Qt-based libraries),

the idea is easy derived to just extend the libraries’ buildsystem to also spit out QCH files during the package builds.

It’s all prepared, can ship next week, latest!!1

Which would just be a simple additional target and command, invoking doxygen with some proper configuration file. Right? So simple, you wonder why no-one had done it yet

Some initial challenge seems quickly handled, which is even more encouraging:
for proper documentation one also wants cross-linking to documentation of things used in the API which are from other libraries, e.g. base classes and types. Which requires to pass to doxygen the list of those other documentations together with a set of parameters, to generate proper qthelp:// urls or to copy over documentation for things like inherited methods.
Such listing gets very long especially for KDE Frameworks libraries in tier 3. And with indirect dependencies pulled into the API, on changes the list might get incomplete. Same with any other changes of the parameters for those other documentations.
So basically a similar situation to linking code libraries, which proposes to also give it a similar handling: placing the needed information with CMake config files of the targeted library, so whoever cross-links to the QCH file of that library can fetch the up-to-date information from there.

Things seemed to work okay on first tests, so last September a pull request was made to add some respective macro module to Extra-CMake-Modules to get things going and a blog post “Adding API dox generation to the build by CMake macros” was written.

This… works. You just need to prepare this. And ignore that.

Just, looking closer, lots of glitches popped up on the scene. Worse, even show stoppers made their introduction, at both ends of the process pipe:
At generation side doxygen turned out to have bitrotted for QCH creation, possibly due to lack of use? Time to sacrifice to the Powers of FLOSS, and git clone the sources and poke around to see what is broken and how to fix it. Some time and an accepted pull request later the biggest issue (some content missed to be added to the QCH file) was initially handled, just yet needed to also get out as released version (which it now is since some months).
At consumption side Qt Assistant and Qt Creator turned to be no longer able to properly show QCH files with JavaScript and other HTML5 content, due to QWebKit having been deprecated/dropped and both apps in many distributions now only using QTextBrowser for rendering the documentation pages. And not everyone is using KDevelop and its documentation browser, which uses QWebKit or, in master branch, favours QWebEngine if present.
Which means, an investment into QCH files from doxygen would only be interesting to a small audience. Myself currently without resources and interest to mess around with Qt help engine sources, looks with hope on the resurrection of QWebKit as well as the patch for a QtWebEngine based help engine (if you are Qt-involved, please help and push that patch some more!)

Finally kicking off the production cycle

Not properly working tools, nothing trying to use the tools on bigger scale… classical self-blocking state. So time to break this up and get some momentum into, by tying first things together where possible and enabling the generation of QCH files during builds of the KDE Frameworks libraries.

And thus to current master branches (which will become v5.36 in July) there has been now added for one to Extra-CMake-Modules the new module ECMAddQch and then to all of the KDE Frameworks libraries with public C++ API the option to generate QCH files with the API documentation, on passing -DBUILD_QCH=ON to cmake. If also having passed -DKDE_INSTALL_USE_QT_SYS_PATHS=ON (or installing to same prefix as Qt), the generated QCH files will be installed to places where Qt Assistant and Qt Creator even automatically pick them up and include them as expected:

KDevelop picks them up as well, but needs some manual reconfiguration to do so.

(And of course ECMAddQch is designed to be useful for non-KF5 libraries as well, give it a try once you got hold of it!)

You and getting rid of the remaining obstacles

So while for some setups the generated QCH file of the KDE Frameworks already are useful (I use them since some weeks for e.g. KDevelop development, in KDevelop), for many they still have to become that. Which will take some more time and ideally contributions also from others, including Doxygen and Qt Help engine maintainers.

Here a list of related reported Doxygen bugs:

• 773693 – Generated QCH files are missing dynsections.js & jquery.js, result in broken display (fixed for v1.8.13 by patch)
• 773715 – Enabling QCH files without any JavaScript, for viewers without such support
• 783759 – PERL_PATH config option: when is this needed? Still used?
• 783762 – QCH files: “Namespaces” or “Files” in the navigation tree get “The page could not be found” (proposed patch)
• 783768 – QCH files: classes & their constructors get conflicting keyword handling< (proposed patch)
• YETTOFILE – doxygen tag files contain origin paths for “file”, leaking info and perhaps is an issue with reproducible builds

And a related reported Qt issue:

• QTBUG-60933 – No qtdbus.tags file generated

There is also one related reported CMake issue:

• 16990 – Wanted: Import support for custom targets (extra bonus: also export support)

And again, it would be also good to see the patch for a QtWebEngine based help engine getting more feedback and pushing by qualified people. And have distributions doing efforts to provide Qt Assistant and Qt Creator with *Web*-based documentation engines (see e.g. bug filed with openSUSE).

May the future be bright^Wdocumented

I am happy to see that Gentoo & FreeBSD packagers have already started to look into extending their KDE Frameworks packaging with generated API dox QCH files for the upcoming 5.36.0 release in July, with other packagers planning to do so soon as well.

So perhaps one not too distant day it will be just normal business to have QCH files with API documentation provided by your distribution not just for the Qt libraries itself, but also for every library based on them. After all documentation has been one of the things making Qt so attractive. As developer of Qt-based software, I very much look forward to that day

Next stop then: QML API documentation

I'm glad to announce that a first stable version of Brooklyn is released!
What's new? Well:

• Telegram and IRC APIs are fully supported;
•  it manages attachments (even Telegram's video notes), also on text-only protocols through a web server;
• it has an anti-flood feature on IRC (e.g. it doesn't notify other channels if an user logs out without writing any message). For this I've to say "thank you" to Cristian Baldi, a W2L developer which has this fabulous idea;
• it provides support for edited messages;
• SASL login mechanism is implemented;
• map locations are supported through OpenStreetMap; 
• you can see a list of other channels' members typing "botName users" on IRC or using "/users" command on Telegram;
• if someone writes a private message to the bot instead of in a public channel, it sends him the license message "This software is released under the GNU AGPL license. https://phabricator.kde.org/source/brooklyn/";

My project for Blue Systems is maintaining Calamares, the distro-independent installer framework. Not surprisingly, working on it means installing lots of Linux distro’s. Here’s my physical-hardware testing setup, which is two identical older HP desktop machines and a stack of physical DVDs. Very old-school. Often I use Virtual Box, but sometimes the hum of a DVD is just what I need to calm down. There’s a KDE Neon, a Manjaro and a Netrunner DVD there, but the machine labeled Ubuntu is running Kannolo and sporting an openSUSE Geeko.

I’m all for eclecticism.

So far, I’ve found one new bug in Calamares, and fixed a handfull of them. I’m thankful to Teo, the previous Calamares maintainer, for providing helpful historical information, and to the downstream users (e.g. the distros) for being cheerful in explaining their needs.

Installing a bunch of different modern Linuxen is kind of neat; the variations in KDE Plasma Desktop configuration and branding are wild. Nearly all of them have trouble being usable on small screen sizes (e.g. the 800×600 that Virtual Box starts with — this has since been fixed). They all seem to install Virtual Box guest additions and can handle resizes immediately, so it’s not a huge issue, but just annoying. I’ve only broken one of my Linux installs so far (running an update, which then crashed kscreenlocker, and now it just comes up a black screen). I’ve got a KDE Neon dev/unstable as my main development VM set up, with KDevelop and the whole shizzle .. it’s very nice inside my KDE 4 desktop on FreeBSD.

I’ve got two favorite features, so far, in Linux live CDs and in KDE Plasma installations: ejecting the live CD on shutdown (Neon does this) and skipping the confirmation screen + 30 second timeout when clicking logout or shutdown (Netrunner does this).

So, time to hunker down with the list of issues, and in the meantime: keep on installin’.

This is my first blog post. It’s a great opportunity to start documenting my journey as a software engineer with my GSoC project with digiKam as a part of KDE this summer.

Hi

There’s a lot I did in the last 2 weeks and since I did not update the blog last week, this post is going to include last 2 week’s progress.

Before I begin with what I did, here’s a quick review of what I was working on and what had been done.

I started porting Cantor’s Qalculate backend to QProcess and during the first week I worked on establishing connection with Qalculate, for which we use qalc and some amount of time was spent parsing the output returned by qalc

Qalculate backend as of now uses libqalcuate API for computing the result. To successfully eliminate the direct use of API all the commands should make use qalc, but since qalc does not support all the functions of Qalculate, I had to segerate the parts depending on API from qalc. For instance, qalc does not support plotting graphs.

The version of qalc that we are using supports almost all the major functionalities of Qalculate but there are a few things for which we still depend on the API directly

I will quickly describe what depends on what

API
* help command
* plotting
* syntax highlighter
* tab completion

qalc
* basic calculations: addition, subtraction etc
* all the math functions provided by Qalculate: sqrt(), binomial(), integrate() etc
* saving variables

Segregating part was easy. The other important thing I did was to form a queue based system for the commands that are required to be processed by qalc

Queue based system

The two important components of this system are:

1. Expression Queue :- contains the expressions to be processed
2. Command Queue:- contains commands of the expression being processed.

* The basic idea behind this system is , we compute only one expression at a time, mean while if we get more expressions from user, we store them in the queue and process them once the current expression being processed is complete.

* Another important point is , since an expression can contain multiple commands, we store all the commands for an expression in command queue and just like we process one expression at a time, we are going to process one command at a time. i.e we are going to give QProcess only one command at a time, this makes the output returned by QProcess less messy and hence it’s easier to parse

* Example: Expression1 = (10+12, sqrt(12)) : this expression has multiple commands. The command queue for the same will have two commands.

expression queue                                               command queue

[ expression 1 ] ——————————————-> [ 10+12 ], [ sqrt(12) ]

[ expression 2] ——————————————-> [ help plot ]

We solve all the commands of expression1 , parse the output and then move on to expression2 and this goes on till the time expression queue is empty

Apart from this I worked on Variable model of Qalculate. Qalc provides a lot of variations of save command. Different commands available are:

Not every command mentioned below has been implemented but the important ones have been.

1. save(value, variable, category, title): Implemented

This function is available through the qalc interface and allows the user to define new variables or override the existing variables with the given value.

2. save/store variable : Implemented
This command allows the user to save the current result in a variable with the specified name.

Current result is the last computed result. Using qalc we can access the last result using ‘ans’, ‘answer’ and a few more variables.

3.save definitions : Not implemented

Definitions include the user defined variables, functions, units .

4. save mode: Not implemented
mode is the configuration of the user which include things like ‘angle unit’, ‘multiplication sign’ etc.

With this most of the important functionalities have been ported to qalc but there are still a few things for which we depend on the API directly. Hopefully, in the future with the newer version of qalc we will be able to remove the direct use of API from Cantor

Thanks and Happy hacking

I really wanted to say that Krita was the first KDE Frameworks 5-based application available in the official FreeBSD ports tree (so that pkg install krita just works), but it turns out that labplot has been KF5-based for a month or more and no-one noticed.

Nonetheless, three cheers for Krita and Calligra, which have been updated to the latest, modernest versions.

This is the start of a whole flood of updates, although Plasma is still going to take a while. Several things have come together to make this update possible:

• FreeBSD KDE CI is running, so we can keep a close(r) eye on upstream. (This is what runs in KDE’s CI system, for FreeBSD)
• KDE FreeBSD CI is running, so we can keep a close eye on ourselves. (This is what runs in FreeBSD’s CI systems, for KDE)
• Both KDE and FreeBSD have Phabricator review systems, one for changes to downstream packaging, one for changes to upstream code.
• KDE FreeBSD ports development is happening in a GitHub fork of the official FreeBSD ports tree.

With good CI and a good review process, we’ve been much happier getting packaging-fixes upstream than ever before. The CI catches unpleasant changes (hey, k3b has turned red, what’s up? Patches forthcoming ..) before they are released. The packaging CI is good for keeping track of where we are in packaging things ourselves. Since there’s a fair amount of package-shuffling going on, that’s important to have in hand. Finally the move to a git clone of the official ports tree makes it much easier to do small topic branches (e.g. updating Frameworks), test, and merge than we ever could with the SVN-based tree.

There’s a handful of smaller updates in-flight, alongside the Great Big Plasma5 branch, which is now shrinking as parts of it start to show up in the official ports already.

KIO Slaves are out-of-process worker applications that perform protocol-specific communications. To provide local file handling file managers use the file ioslave(file:/). Up until now file management with root access was forbidden in file ioslave. But with this week’s work situation might just change for good.

During the past week and a half, I worked on getting polkit support to delete, copy, rename, symlink and mkdir function. My attempts at getting these file operations working correctly inside a read-only folder were almost successful. I was able to add polkit support to all but the copy file operation. To get the copy function working I needed to be able to open a file with elevated privilege in the KAuth helper and send back the file descriptor to file ioslave for further processing. It was the latter part that proved to be the major obstacle. Since file descriptors are non-negative integers it may be instinctive to embed them in QVariant and send them back to ioslave over D-Bus. However, they have more to them than just being an integer. Owing to this fact the integer value is pretty much meaningless outside its host process. Therefore, even though I was able to retrieve the file descriptor in ioslave, doing any kind of file processing ended in failure. Although unix local domain socket is apt for this task, due to my unfamiliarity with network programming and the unavailability of any equivalents in Qt, I had to postpone my work on the copy function for a while.

Coming back to changes. I had added polkit support to the delete function prior to sending my GSOC proposal as a proof of concept. So, during this time I mostly made it a bit modular and separated, what seemed to be, the boilerplate code. Getting polkit support to rest of the lot was simple as the code was similar to that of delete. After these successive changes, a KIO client can now perform the following tasks as a privileged user without having to start itself as root.

1. Delete files and folders.
2. Rename files and folders.
3. Create folders.
4. Create symbolic links.

You can view all of my changes in cgit.kde.org. To avoid any convolution in future I went for creating a separate branch for every file management function instead of a single, difficult-to-manage branch. Testing the upgraded ioslave needs some changes in dolphin as well. Since the changes are trivial and cloning dolphin seemed futile, I have hosted my patches for dolphin on github. Apart from the clone, I have some patches on phabricator as well, precisely D6197, D6198 and D6199. Apply them in order to test polkit support in delete file operation. So, if you are getting bored and looking forward to doing some unpaid labor you can review my patches, alternatively, you can also fork my kio clone and see the changes yourself. (:

Here’s a demo for the curious minds.

That’s all for this week folks.

Hi folks, it's been a while since my last post here. I had a hard time to start on GSoC but now that I have successfully graduated from the university (Computer Science BSc) I have all my time for my project. While learning for the exams and preparing for my final exam I've been talking to my mentors often to share our ideas about the project. Thanks to the fact that I have already worked previously (and continously after GSoC) on LabPlot I can implement the needed features much easier and quicker now than last year :) Now that I have my own branch and a few new classes added I can continue the adventure with LabPlot! See you soon! :)

“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.kde.org

Ever since we started working on Kube we faced the conundrum of how to allow Kube to innovate and to provide actual additional value to whatever is already existing out there, while not ending up being a completely theoretical exercise of what could be done, but doesn’t really work in practice. In other words, we want to solve actual problems, but do so in “better” ways than what’s already out there, because otherwise, why bother?

I put “better” into quotes because this is of course subjective, but let me elaborate a bit on what I mean by that.

Traditionally, communication and organization has been dealt with using fairly disjoint tools, that we as users then combine in whatever arbitrary fashion that is useful to us.

For instance:

• EMail
• Chat
• Voice/Video Chat
• Calendaring
• Taskmanagement
• Notetaking

However, these are just tools that may help us work towards a goal, but often don’t support us directly in what we’re actually trying to accomplish.

My goto example; Jane wants to have a meeting with Jim and Bob:

• Jane tries to find a timeslot that works for all of them (by mail, phone, personally…)
• She then creates an event in her calendar and invites Jim and Bob, who can in turn accept or decline (scheduling)
• The meeting will probably have an Agenda that is perhaps distributed over email, or within the event description
• A meeting room might need to be booked, or an online service might need to be decided.
• Once the meeting takes place the agenda needs to be followed and notes need to be taken.
• Meeting minutes and some actionable items come out of the meeting, that then, depending on the type of meeting, may need to be approved by all participants.
• So finally the approved meeting minutes are distributed and the actionable items are assigned, and perhaps the whole thing is archived somewhere for posterity.

As you can see, a seemingly simple task can actually become a fairly complex workflow, and while we do have a toolbox that helps with some of those steps, nothing really ties the whole thing together.

And that’s precisely where I think we can improve.

Instead of trying to do yet another IMAP client, or yet another calendaring application a far more interesting aspect is how can we improve our workflows, whatever tools that might involve.
Will that involve some email, and some calendaring and some notetaking? Probably, but it’s just a means to and end and not an end by itself.

So if we think about the meeting scheduling workflow there is a variety of ways how we can support Jane:

• The scheduling can be supported by:
  • Traditional iCal based scheduling
  • An email message to invite someone by text.
  • Some external service like doodle.com
• The agenda can be structured as a todo-list that you can check off during the meeting (perhaps with time limits assigend for each agenda item)
• An online meeting space can be integrated, directly offering the agenda and collaborative note-taking.
• The distribution and approval of meeting minutes can be automated, resulting in a timeline of past meetings, including meeting minutes and actionable items (tasks) that fell out of it.

That means however that rather than building disjoint views for email, calendar and chat, perhaps we would help Jane more if we built and actual UI for that specific purpose, and other UI’s for other purposes.

Views

So in an ideal world we’d have an ideal tool for every task the user ever has to execute which would mean we fully understand each individual user and all his responsibilities and favorite workflows….
Probably not going to happen anytime soon.

While there are absolutely reachable goals like Jane’s meeting workflow above, they all come at significant implementation cost and we can’t hope to implement enough of them right off the bat in adequate quality.
What we can do however is keeping that mindset of building workflows rather than IMAP/iCal/… clients and setting a target somewhere far off on the horizon and try to build useful stuff along the way.

For us that means that we’ve now set the basic structure of Kube as a set of “Views” that are used as containers for those workflows.

This is a purposefully loose concept that will allow us to transition gradually from fairly traditional and generic views to more purposeful and specific views because we can introduce new views and phase out old ones, once their purpose is helped better by a more specific view.

Some of our initial view ideas are drafted up here: https://phabricator.kde.org/T6029

What we’re starting out with is this:

• A Conversations view:
  While this initially is a fairly standard email view, it will eventually become a conversation centric view where you can follow and pick up on ongoing conversations no matter on what medium (email, chat, …).

• A People view:
  While also serving the purpose of an addressbook it is first and foremost a people centric way to interact with Kube.
  Perhaps you just want to start a conversation that way, or perhaps you want to lookup past interactions you had with the person.

• A composer view:
  Initially a fairly standard email composer but eventually this will be much more about content creation and less about email specifically.
  The idea is that what you actually want to do if you’re opening the composer is to write some content. Perhaps this content will end up as email,
  or perhaps it will just end up on a note that will eventually be turned into a blogpost, chances are you don’t even know before you’re done writing.
  This is why the composer implements a workflow that starts with the starting point (your drafts) then goes over to the actual composer to create the content, and finally allows you to do something with the content, i.e. publish or store it somewhere (for now that only supports sending it by email or saving it as draft, but a note/blog/… could be equally viable goals).

The idea of all this is that we can initially build fairly standard and battle-tested layouts and over time work our way towards more specialized, better solutions. It also allows us to offload some perhaps necessary, but not central features to a secondary view, keeping us from having to stuff all available features into the single “email” view, and allowing us to specialize the views for the usecases they’re built for.

KTechLab, the IDE for microcontrollers and electronics has joined KDE. Below I’m summarizing its current status and plans.