Chinese Lunar Calendar Support in Kdelibs

F H bbluldd at
Thu Nov 11 06:52:01 GMT 2010

Thanks a lot for the detail replay. I am very much agree with your points.

When I did the hacking, I already felt bad to make the ccal/NOVAS codes into
one big stuff.

For licensing issue, at the very beginning, how about separate those
astronomical algorithms for the Chinese calendar into a standalone library
outside the kde codes, and let the library or end-user worry about the
licensing problem. And if in the future, Kstars or Marble terms provide
shared library for use, we switch to KDE's own library to compute the
Chinese calendar. The reason for such a consideration is that it could be
many other years to wait for until a solid-considered library is presented.

And for the libnovas-or-NOVAS issue, I just did a quick comparison of the
lunar system codes in libnovas and ccal/NOVAS. It seems that libnovas is not
sufficient to compute some lunar related things required for the Chinese
lunar calendar.  For example, libnovas does not have some algorithms from
Ch. 47 of Meeus' book, for computing the number of lunations. If we decide
to use libnovas, we may have to implement again what the NOVAS codes have
implemented. That may also take some long time.

I am happy that "display two calendars at once" has already been considered.
That is definitely the right solution for multi-calendar users, including
the Chinese users.  And what I want to mention is that display a single
Chinese lunar calendar alone is of less use for almost all the Chinese
users. So without a multi-calendar-display mechanism, building the
KCalendarSystemChinese would be in vain.

>From kde 3, it was hoped that the Chinese calendar could be implemented. I
will be very happy if we can have it before kde 5. And please do help to
make that happen.



On Wed, Nov 10, 2010 at 11:31 PM, John Layt <johnlayt at> wrote:

> Hi,
> First of all, thanks for your efforts, as the maintainer of KCalendarSystem
> I
> always welcome new contributions.
> Unfortunately, this patch has exactly the same problems as the last one.
> Firstly, it is not clear that the licensing issues have been resolved.
>  While
> the required ccal code has been relicensed under the LGPL (I have yet to do
> a
> full file-by-file check), it also includes copyright statements for the
> Lunar
> Outreach code for which the licensing is unclear.  It was "for
> non-commercial
> use only", Liang Qi said it had been relicensed but the link he gave is now
> dead.  That code seems to just be standard algorithms from "Astrinomical
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