Plasma Weather widget: add your favorite weather data provider

So Plasma 5.6 has seen the revival of the Weather widget that is part of KDE Plasma Add-ons module (revival as in: ported from Plasma4 API to Plasma5 API).
(And even got the interesting honour to be mentioned as the selling item in the headline of a Plasma 5.6 release news article by a bigger German IT news site, oh well 🙂 )

This revival was concentrating for 5.6 to restore the widget in its old state, without any bugs. But that’s not where things are to end now…

And you, yes, you, are invited and even called in to help with improving the widget, and especially for connecting to more weather data providers, incl. your favourite one.

For a start, let’s list the current plans for the Weather widget when looking at the next Plasma release, 5.7:

  • Overhaul of look (IN PROGRESS)
  • Breeze-style weather state icons (IN PROGRESS)
  • also temperature displayed in compact widget variant, like on panel (TODO)
  • support for more weather data providers (YOUR? TODO)
  • privacy control which weather data providers are queried on finding weather stations (YOUR? TODO)

Overhaul of widget look

The KDE meta sprint at CERN (of groups WikiToLearn, Plasma, VDG, techbase wiki cleanup) at begin of this March, where I mainly went for techbase wiki cleanup work, of course was a great occasion to also work face-to-face with Plasma developers and VDG members on issues around the Weather widget, and so we did. Marco helped me to learn more about Plasma5 technologies which resulted in some small bugs fixed in the widget still in time for Plasma 5.6 release.
Ken presented me the drafts for the look & design and the config of the weather widget that he had prepared before the sprint, which we then discussed. Some proposals for the config could already be applied in time for Plasma 5.6 release (those without need for changed UI texts, to not mess the work of the translators). The rest of it, especially the new look & layout of the widget, is soon going to be transferred from our minds, the notes and the photos taken from the sketches on the whiteboard at CERN into real code.

Breeze-style weather state icons

Ken also did a Breeze style set of the currently used weather state icons. While touching the icons, a few icon naming issues are going to be handled as well (e.g. resolving inconsistent naming pattern or deviation from the weather state icon names actually defined in the XDG icon naming spec (see Table 12. Standard Status Icons). Should soon be done as well.

Temperature display in compact widget variant

One thing that has been missing also from the old version of the Weather widget is the display of the current temperature in the compact widget variant, where now only the current weather condition is shown (e.g. when on the panel). While some weather data providers (like wetter.com) do not provide that detail, so there is nothing to display, others do, and often it is pretty nice to know (clear sky can happen with temperatures of any kind, so it’s good information about if and then what kind of jacket to put on before stepping outside). First code is drafted.

Now, finally the things were you can improve things for yourself and others:

Supporting more weather data providers

The Weather widget does not talk to any weather data providers directly. Instead it talks to a weather dataengine (currently part of the Plasma Workspace module), to query for any weather stations matching the entered location search string when configuring the widget and to subscribe to the data feed for a given weather station from a given weather data provider.
That weather dataengine itself again also does not talk directly to any weather data providers. Instead it relies on an extendable set of sub-dataengines, one per weather data provider.

The idea here is to have by the one weather dataengine an abstraction layer (he, after all this is KDE software 😉 ) which maps all weather data services into a generic one, so any UI, like the Weather widget, only needs to talk one language to whoever delivers the data.
Which works, more or less. Because of course there are quite some weather data specifications out there, what else did we expect 😛 And possibly the spec interpretations also vary as usual.

((You might think: “Well, screw that over, there is only one user of the weather dataengine, so integrate that directly into the Weather widget!”
While that might be true right now, it does not need to stay this way. There are ideas like showing the weather forecast also with the days in Plasma calendar widgets. Having a KRunner plugin to quickly request weather in some place. Or having a wallpaper updater reflecting the current weather by showing matching images, yes, not everyone has the joy to work close to a window, enjoy if you do. And also alternative weather widgets with another UI, remember also the WeatherStation widget in kdeplasma-addons (still waiting for someone to port it), which focussed on details of the current weather state. These kind of usages might prefer a normalized model of weather data as well, instead of needing custom code for each and any provider again. Actually long-term such a model would be interesting outside of Plasma spheres, e.g. for any calendaring apps, for a plugin for Marble-based apps showing weather states over a map or whatever other fancy uses there can be. Feel free to share ideas in the comments, to improve motivation for creating such a Plasma-independent lib!))

While I only took over kind of maintainership in the last weeks, so did not design the current system myself, I still think it’s a good approach, having in mind reusable UIs and relative independence from any given weather data providers. So for now I do not plan to dump that, simply lacking a more promising alternative.

So, given you are still reading this and thus showing me and yourself your interest 🙂 let’s have a closer look:

The sub-dataengines for the different weather data providers have been named “ion”s. On the code level they are subclasses of a class IonInterface, which itself is a subclass of Plasma::DataEngine.
See here for the header defining IonInterface: https://quickgit.kde.org/?p=plasma-workspace.git&a=blob&f=dataengines%2Fweather%2Fions%2Fion.h

This header and the respective lib libweather_ion are public and should be installed with the devel packages of Plasma Workspace. Which means you should be able to develop your custom ion as 3rd-party developer without the need to checkout the plasma-workspace repository and develop it in there.

Plasma 5.6 itself installs three such ions:

  • wetter.com: adapter to service of the private company running wetter.com
  • envcan: adapter to service of Environment Canada, by Government of Canada
  • noaa: adapter to service of USA’s National Oceanic and Atmospheric Administration

Find their sources here: https://quickgit.kde.org/?p=plasma-workspace.git&a=tree&f=dataengines%2Fweather%2Fions

In that source folder you will also spot a bbcukmet ion, for the BBC weather service. While being ported to build and install at least with Plasma5, the service API of BBC as used by the code seems to have been either changed or even removed. So that ion is currently disabled from the build (uncomment the #add_subdirectory(bbcukmet) to readd it to the build). Investigations welcome.
Update: There are patches for the Plasma4 version of the bbcukmet ion to make it work again with current BBC service API. See below in the comments for detailed info. Should be easy work and a chance to contribute also for beginners.
Update2: Those patches have been used to restore the bbcukmet ion, it will be part of Plasma 5.6.2 and later. Still would be good to have someone look closer at it, there is room for improvements.

Another old ion which though already got removed during the revival was a more fun one: there used to be a Debian “weather” service (random related blog post), which reported the status of Debian-based distros by number of working packages as weather reports, and this ion connected to them. But the service died some years ago, so the ion was just dead code now (find the unported code in versions of “Plasma 5.5” and before)

Talking about funny weather reports: why not write an ion for the CI system Jenkins, e.g. with build.kde.org, which while perhaps not being able to give forecasts at least reports the current build state, with builds mapped to stations. After all the short report for a build uses the weather metaphor, see https://build.kde.org/ 🙂

For more serious weather data provider ions again, as you surely know or can guess, there are many more public & private weather data providers than those 3 currently supported. And they not only may have a better coverage of your local area, but might also provide more data or more suited ones.

Please also see the proposal for using “weather data from the open data initiatives” in a comment on the first blog post on the Weather widget.

It would be great to have a larger selection of weather data providers supported in Plasma 5.7. So while having your ion as 3rd-party plugin somewhere else is fine, consider maintaining it inside one of the Plasma repositories, either with the existing ions in the repo plasma-workspace or as part of addons in the repo kdeplasma-addons. This should ensure more users and also more co-developers.

Do a good check of the licenses for using the data services of the weather data providers. Especially public ones should be fine given their purpose, but if in doubt after reading the details, ask the providers.

Privacy control

One issue in the old and current Weather widget code is that when searching for a weather station suiting the users desire, as expressed by the location search string, all currently installed ions are queried. Which of course is a problem from a privacy point of view. And will be worse the more ions there will be.

So there needs to be a way to limit the scope of ions that would be queried. Given that dataengines by design should be used by all kind of dataengine consumers, a Weather widget-only solution might be only a short jump here. There are very possibly other Plasma modules talking to remote services as well, like geolocation services. And ideally one is able to control system-wide (so even beyond Plasma scope) which remote services are allowed and which not.

Until such a global solution exists a Weather widget-only solution is better than nothing surely. Still, it needs to be designed UI-wise, so a job to be picked up by someone 🙂

Getting started with your own ion

So while I am currently impeded these days from hacking, among other things by waiting for new development-capable hardware being delivered (disadvantage of small towns: need to use an online shop for special hardware desires, and there latency unit is days, not minutes, especially bad when wrong stuff is delivered and then also holidays get into the game. Looking on the bright side of life, my old hardware only broke right after the CERN sprint, not before 🙂 )…
… Do not hesitate to look into things already. I would have liked to provide a KAppTemplate-package with an ion sample in this post already, so you could experiment right away. But perhaps you are experienced enough to get a new ion working by looking at the existing ones. If not, in a few weeks hopefully there should be a template, so watch out.
Update: There is now such a template, see this blog post.

And do not hesitate to ask for support on #plasma on irc or on the Plasma mailinglist, I received lots of help there with the Weather widget porting, so you should when trying to write an ion 🙂

Selecting text in the Calligra-powered Okular plugin for ODT, DOC, DOCX & WPD

Traveling 8+ hours on the train all the way through Germany to Geneva in Switzerland, where CERN is located (its area spreading across the border to France actually), the place of the WikiToLearn-Plasma-VDG-TechbaseOverhaul meeting, was also a good chance to first spend some time again on a sprint-unrelated, but still KDE-related item, which is adding support for text selection to the Calligra-powered Okular plugin for text documents.

With some first satisfying prototyping results, where selection highlight is rendered at the correct positions and the correct chars being copied:
Calligra Okular plugin first text selection support

Polishing this up is left for the trip back home on Sunday. Looks promising so far, you hopefully soon will be able to select text from your DOCX, DOC, WPD and ODT files you view in Okular using the plugins from Calligra (once both Okular based on KF5/Qt5 and Calligra 3.0 are released, TBD).

One thing learned on the train: forcing your SchuKo-style power plug into the Swiss train’s on-board Swiss-style power socket might work (SchuKo connectors have a slightly bigger diameter), yes.
But: it takes some time to get it out again, without destroying the socket, so it is best started to be done some time before the switch-trains-here station is reached, not only a few seconds, which has one run the risk of not getting out in time. Or having to leave the power supply behind, better to be avoided as well 🙂

TechBase Wiki Overhaul at CERN

KDE’s techbase wiki, “the primary place for technical information about KDE targeted at developers, ISVs and sysadmins”, has been gone lost a little during the transition of KDE software to KF5 and Plasma5.
An unsatisfying situation, so a few people including me decided to use the opportunity of the scheduled KDE contributor meeting at Europe’s CERN this second week of March, originally for WikiToLearn, Plasma & VDG, to also meet up for preparing and starting an overhaul of techbase. And there we are already!

It’s great to be here at CERN, a place where Europe feels like the good old late last century Europe. It is exciting to be in an environment where people work together for the good and for more knowledge, and with such excellence. Very inspiring.

A nice sideeffect of doing this big sprint here at CERN is that it also means getting a few talks delivered about the CERN and its activities. Where one can learn that a flying mosquito or big fastfood items are suitable quantification units when it comes to explaining what gets accelerated in the underground here and how 🙂

Once this morning we all had been introduced to our host and the location as well as us to ourselves, the different KDE teams, and our each goals at the sprint, we spread out into the IdeaSquare building and grouped again in the in-door containers or in-door bus decks (“Ceci n’est pas un bus” only by definition, even if it looks, smells and feels like a real 1960 London double-decker bus, that was also said to have been driven all the way from London straight into the building by one of the employees) to start our work.
We TechBase overhaulers got a good run so far, starting with revisiting the purpose of TechBase, collecting issues with the current content on TechBase (or not on it) and sketched first solutions that would help to fix or prevent those issues. And discussed with Plasma and WikiToLearn people about that a little.
No content was touched so far. Soon more about it.

When in the evening the daily recap was done, it seemed all groups had made some good progress today.

Having a rather stiff northern culture as background, it is heart-warming to experience lots of Italian students from the WikiToLearn project occupying and running the kitchen here in the IdeaSquare building for creating lunch and dinner for everyone and vigorously celebrating the joy of food (with ingredients bought right behind the border in the less expensive supermarket in France, small is this continent). One of the terms to be learned is “abbiocco”, left without direct word matches in the northern languages present, interesting.

With the Plasma and VDG people present, somewhen the next days they and me will also take advantage of that and work a little together on both improving the revived Plasma5 AddOns Weather widget and also getting Breeze-style icons for it 🙂

This meeting at CERN is not only made possible by our hosts here at CERN, but also by you, the donators to the KDE e.V., which is forwarding your financial support also to us all who have come here, to cover parts of travel and accomodation.
If you haven’t already, consider joining the donators. Click the banner for more info:
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Will the Addons Weather widget be revived for Plasma 5.6?

If you are deep in coding mode and cannot afford to turn your head or even your eyes to look through the window at outside to check the current weather… or if you are deep down below ground plumbing at your black hole farming machine and now preparing your way home and are unsure whether to put on a rain jacket or the sunglasses… what is there to help you? A widget on your computer telling you about the weather, right.

Plasma5 so far was missing the port of the weather widgets which were part of the Plasma Addons package with the older Plasma. While there are nice Plasma5 weather widgets on kde-apps.org (1, 2) I wanted the weather widget back I was used to.

Time for “Scratch your itch!”. Starting myself with no clue about Plasma dataengines and also about the new Plasma5 QML-centric widget technology, there was enough material to be found and samples to copy from to port the old weather widget code over to the new Plasma5 world. Also was there great support by the Plasma developers (special thanks to Kai-Uwe and Marco) who quickly helped out with questions, gave good review or the next day fixed bugs elsewhere I hit on the way.

This week there was the feature freeze for Plasma 5.6, and of course it would be nice to share this widget already with everybody again. Did we make it in time?

Teaser: Yes 🙂

Addons Weather widget showing forecast for Geneva and Lisbon

Seems its time for rain jacket in Geneva, while sunglasses are okay in Lisbon 🙂

There is one bigger issue currently known: sometimes after configuring a new weatherstation to be used, there is no instant data update, so the widget will be blank. This blank widget should heal itself on the next weather report update interval (or on the next Plasma restart). Hopefully we soon find the reason to fix this.

There is still the Weatherstation widget left in Plasma Addons, waiting for a port as well (nothing I am interested in, so no itch to scratch here). Feel encouraged to give it a go to port it yourself and become the happy maintainer of a Plasma5 widget as well 🙂