Which Islamic calendar is commonly used?

[Fusion Future]

On 1/11/23 22:02, Andika Triwidada wrote:
>     So Islamic calendar variants are categorized as below:
>     [A] Religious: Based on the sighting of the hilal. Actual dates
> vary by location.
>     Algorithmic
>     [B1] Tabular: ICU "civil", Microsoft "HijriCalendar"
>     [B2] Umm Al-Qura: Saudi Arabia and others, Microsoft "UmAlQuraCalendar"

Thank you Andika.

I added the 3 kinds of Islamic calendars in 
https://invent.kde.org/plasma/kdeplasma-addons/-/merge_requests/317

Hope they can cover most cases.

AboutReligious, do you know where I can get the guidance to calculate 
Islamic calendar date according to location (and is it moon position or 
geographical location)? Because Islamic Calendar (Astronomical) in 
libicu does not consider longitude/latitude, but the algorithm does 
calculate moon position, so I am confused here.

Reference: 
https://github.com/unicode-org/icu/blob/030fa1a4791ee7c2f58505ebb61253c3032916ec/icu4c/source/i18n/astro.cpp#L1066