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diff --git a/content/26/index.md b/content/26/index.md new file mode 100644 index 0000000..e284afc --- /dev/null +++ b/content/26/index.md @@ -0,0 +1,67 @@ ++++ +date = 2024-10-19T20:02:17+02:00 +title = "Night-time icons for Plasma's DWD backend" + +[taxonomies] +tags = ["contrib", "kde"] + +[extra] +related = [] ++++ + +For a couple of weeks now I have been using Plasma's built-in weather report +system. It supports various different sources for weather observations and +forecasts, one of which is my preferred service, [Deutscher +Wetterdienst](https://www.dwd.de) (DWD). Once the report location is set up, Plasma +displays the current conditions in the tray - clicking on it gives you an +overview of the next 7 days. + +I've been quite pleased with this; a quick glance at the icon tells you +everything you need to know and the forecast is only one click away. It even +supports DWD's official warning system. There is one small problem with the tray +icon, however. See if you can spot it: + +{{ img(path="icon-day.png", format="png", alt="A screenshot of Plasma's tray +showing a clipboard icon, a media control icon, and a weather icon. The weather +icon is displaying a sun with few clouds in front. The tray is also showing the +time. It is 23:57.", caption="Something's not quite right...") }} + +That's right, I couldn't have possibly taken this image given this post's +timestamp is before 23:57! Good catch. More importantly, however, the icon is +showing the sun when realistically it's going to be dark outside. This has been +annoying me to no end, so a couple of days ago I decided to fix it. + +Since Plasma already comes with weather icons suited for night-time use, I +really only needed a reliable way to tell when to switch to those. After some +spelunking in DWD's [two](https://dwd.api.bund.dev/) +[APIs](https://listed.to/@DieSieben/7851/api-des-deutschen-wetterdienstes), I +found that the latter contains sunrise and sunset times for its forecast +endpoint. The weather report system was already using this endpoint to fetch +forecast data, so it was a rather simple lookup of two values in the API and +then comparing the current observation time to those. + +So, after some preparatory work to make date parsing more robust, I sent a +[merge +request](https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/4848) +upstream which was promptly approved and merged. Finally I could rest easy after +dusk, not having to worry about a sun chasing me around. + +{{ img(path="icon-night.png", format="png", alt="A screenshot of Plasma's tray +showing a clipboard icon, a media control icon, and a weather icon. The weather +icon is displaying a crescent moon with few clouds in front. The tray is also +showing the time. It is 18:57.", caption="... much better!") }} + +There's some more stuff that could be improved in the DWD backend, like station +availability. As far as I can tell, when using the open API, DWD limits access +to weather data depending on whether or not they have the full rights to it. The +API might therefore simply deny access to a station even though it is listed in +in [the official index](https://www.dwd.de/DE/leistungen/klimadatendeutschland/statliste/statlex_html.html?view=nasPublication&nn=16102). +There's no way to find out which station is accessible except to try them all. +To get around this, the DWD backend uses a [very simple +heuristic](https://invent.kde.org/plasma/plasma-workspace/-/blob/69a52cd6fbde80b087f59a633b4ff216c27ddff0/dataengines/weather/ions/dwd/ion_dwd.cpp#L396-403) +based on the first digit of the station ID, since all stations starting with 0 +or 1 seem to work. However, this ignores a number of other, still accessible, +stations. + +I'm planning to look into this further, hopefully finding a better solution so +that users of the DWD backend have access to as many stations as possible. |