Bug 447964

Summary: Astronomical seasons should show all 24 solar terms in addition to just solstices and equinoxes
Product: [Unmaintained] kdeplasma-addons Reporter: Michael Tsang <miklcct>
Component: GeneralAssignee: Plasma Bugs List <plasma-bugs-null>
Status: RESOLVED INTENTIONAL    
Severity: wishlist CC: nate
Priority: NOR    
Version First Reported In: 5.22.5   
Target Milestone: ---   
Platform: Ubuntu   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Michael Tsang 2022-01-05 09:18:28 UTC 
SUMMARY
Astronomical seasons should show the full 24 solar terms in addition to just solstices and equinoxes

STEPS TO REPRODUCE
1. Open digital clock settings
2. Enable lunar phases and astronomical seasons in astronomical events

OBSERVED RESULT
It doesn't show all solar terms, such as "spring commerces", apart from the solstices and equinoxes

EXPECTED RESULT
It shows all 24 solar terms (spread 15° apart along the ecliptic, as used by lunisolar calendars).

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Ubuntu 21.10
(available in About System)
KDE Plasma Version: 5.22.5
KDE Frameworks Version: 5.86.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
Comment 1 Michael Tsang 2022-01-19 10:50:48 UTC 
Apparently the formula of calculating the solar terms is already in https://invent.kde.org/frameworks/kholidays/-/blob/master/src/astroseasons.cpp called periodicTerms, so it may be a simple change to expose all 24 solar terms.
Comment 2 Michael Tsang 2022-01-19 11:07:36 UTC 
Apparently the formula in the book quoted from the source code does not give a formula to calculate the date for arbitrary longitude.
Comment 3 Nate Graham 2022-06-27 19:33:29 UTC 
This is actually currently intentional. We briefly did enable more events by accident as the result of an unrelated bug, and we got tons of negative feedback about it, because it resulted in every single day gaining an event, so the Calendar widget's month grid became full of dots and caused people to be unable to distinguish days with their earthly events from days with only astronomical events.

If we were do to something like this, we would first need to change the Calendar to be able to consider certain events as "minor" so they don't get a dot on the month grid, and then we would need to change the code of the Astronomical Events plugin to mark all astronomical events as minor, so the Calendar widget's month grid doesn't fill up with noisy dots.

I'm marking this as RESOLVED INTENTIONAL for now, but feel free to work on this and then re-open the bug report, if you'd be interested in it.