Re: regression/mensural-ligatures.ly

[Juergen Reuter]

On Wed, 22 Feb 2006, Erik Sandberg wrote:

> Hi Juergen,
>
> IIRC, mensural notation is contributed & supported by you. A regression test
> is broken:
>
> There seem to be some problems with regression/mensural-ligatures.ly. At least
> two problems exist:
> - Dots are handled incorrectly.
> - Notes take up too much horizontal space.
> - lily spits out tons of programmign error messages (could be part of the
> above problems)
>
> Thanks,

Hi, Erik!

Yes, these problems (and a lot of other problems such as accidental 
placing) are known and documented in the code, see lily/*ligature*.cc.  I 
have discussed the horizontal spacing problem with Han-Wen and Jan several 
times, and it looks like the spacing engine either needs a major rewrite, 
or I have to provide a kind of spacing plug-in in order to handle this. 
But my knowledge about the (imho very complex) spacing engine is too 
marginal in order to write a proper engine / plugin.  Maybe at some time I 
should meet the main authors for a hacking session on this topic; but the 
next couple of months I will definitely have no time for such a meeting.

As for the dots, a couple of months ago I started writing code for 
handling these, but I also failed (iirc, some of the relevant data 
structures to manipulate are private; and timing (when exactly to correct 
the dots' position) is extremely critical in order not to break other 
dependencies or provoke crashes due to not timely initialized data).

The error messages typically derive from the fact that I am already 
"overstressing" (or, if you prefer, "abusing") the current spacing engine 
in order to get spacing that at least gets somewhat close to the desired 
spacing.  The error messages themselves sometimes change from time to 
time due to changes to the spacing engine by the main authors.

Mensural notation has always been and still is in a highly experimental 
state (and I think I once explicitly stated it exactly that way somewhere 
in the documentation).  I am sorry, but I fear I can not really help on 
these issues, at least not in the next couple of months. :-(

Greetings,
Juergen