Re: StaffSymbol: behaviour of ledger-line-thickness

[Reinhold Kainhofer]

Am Montag, 31. März 2008 schrieb till Rettig:
> Hi,
> could somebody explain me how ledger-line-thickness behaves? The IR states
> that it should be a pair:
>
> "ledger-line-thickness (pair of numbers)
>     The thickness of ledger lines. It is the sum of 2 numbers: The first is
> the factor for line thickness, and the second for staff space. Both
> contributions are added. "
>
> But I cannot get the staff space bigger (the second number), instead the
> first number influences the thickness of the ledger line a bit, the second
> quite much, that is it becomes so heavy that the spaces almost disappear.

Yes, because they use different units: 
-) The first one is a multiplier for the default thickness (quite small, ~ 
staff-space/10 )
-) The second one is an explicit width (in staff spaces, i.e. the default 
distance between two staff lines or ledger lines)

The final distance is then:
( thickness * line-thickness * #1 ) + #2

Since the default thickness is quite small, of course the first number 
influences the width only a little bit, while the second (measured in 
different units!) increases it a lot.
Actually, the following two settings produce roughly the same (i.e. ledger 
lines so thick that they touch each other:

\override StaffSymbol #'ledger-line-thickness = #'( 10 . 0 )
\override StaffSymbol #'ledger-line-thickness = #'( 0 . 1 )


And, yes, even Han-Wen agrees that this is confusing. See his comment in 
lily/staff-symbol.cc:
  /*
    For raggedright without ragged staves, simply set width to the linewidth.
    (ok -- lousy UI, since width is in staff spaces)
    --hwn.
  */

> the second 
> quite much, that is it becomes so heavy that the spaces almost disappear.
> Please compare the example:

Things work as expected: The default line width is quite small and the first 
number is a multiplier for the default line width. The second one gives an 
additional width in staff space (i.e. the distance between each of the five 
lines of a standard staff).

>   \override StaffSymbol #' ledger-line-thickness  = #' ( 1 . .1 )

This uses the default line width + 1/10 of the staff space = 1/5 staff space

>   \override StaffSymbol #' ledger-line-thickness = #' ( .1 . 1 )

This decreases the line with to 1/10 of its default (1/100 staff space!), but 
adds a full staff space (=distance between two ledger lines!), so of course 
all ledger lines touch each other.


Cheers,
Reinhold
-- 
------------------------------------------------------------------
Reinhold Kainhofer, Vienna University of Technology, Austria
email: address@hidden, http://reinhold.kainhofer.com/
 * Financial and Actuarial Mathematics, TU Wien, http://www.fam.tuwien.ac.at/
 * K Desktop Environment, http://www.kde.org, KOrganizer maintainer
 * Chorvereinigung "Jung-Wien", http://www.jung-wien.at/