Re: scheme numeric values

[Erik Sandberg]

On Thursday 09 March 2006 01.23, Graham Percival wrote:
> Hi all,
>
> As far as I understand, most numbers in lilypond tweaks are measured in
> staff-spaces.  For example,
>
> \override TextScript #'padding = #2.5
> will place TextScript objects 2.5 staff-spaces away from the note they
> are attached to.
>
> If that's correct, then what's happening here?  (example from Appendix
> B, scheme tutorial)
> -----
> This syntax will be used very frequently, since many of the layout
> tweaks involve assigning (Scheme) values to internal variables, for
> example
>
> \override Stem #'thickness = #2.6
>
> This instruction adjusts the appearance of stems. The value 2.6 is put
> into the thickness variable of a Stem object. This makes stems almost
> twice as thick as their normal size.
> -----
>
> The thickness of the stem is obviously not 2.6 staff-spaces, so what
> *is* it measured in?  And how do users know whether a number is being
> measured in staff-spaces or other stuff?

The Fine Manual says (on grob property thickness):
"Bar line thickness, measured in @code{line-thickness}."

Some further digging reveals that all thicknesses are supposed to be measured 
in line-thickness, while distances are measured in staff-spaces. This is 
however not true for all properties yet; e.g., the thickness of beams is 
measured in staff-spaces.

Most of this information can be found in scm/define-grobs.scm.

-- 
Erik