Re: Font questions about absolute

[Aaron Hill]

On 2019-05-11 12:53 pm, Reggie wrote:
> Aaron wow yes I understand the maths perfectly that's my area. Thank 
> you
> your answer is perfect. But as I understand the Gould engraving book 
> and
> other font "normal" standards, how does one handle font size then 
> regardless
> of staff size and paperr? For example, let's say a publshing house 
> wants
> "all tempo marks must be 14pt roman" or "all expressive font must be 
> 12pt in
> parts and 14pt in score"? If the size of your paper and staff size 
> could
> change depending on the size of ensemble, would you then still use 
> absolute
> font sizes to align with explicit needs for font rules? Or would you
> personally eye ball font size and use relative and get it close enough 
> to
> absolute font size. I don't understand the best practice if you want to 
> in
> the end have a certain set point size for certain markings with 
> variable
> paper sizes.

I cannot comment on how to organize projects for clients/publishing 
houses, as all of my work is largely personal.  (Well, technically, it 
is for my church; but I have had the final say on stylistic issues like 
staff and font size.)

But providing you have determined what staff size you intend to use, 
everything else should essentially be fixed.  That should give you a 
basis to ensure that any elements that need a strict font size can have 
it.

If the staff size is variable between different outputs, you may have to 
use the math I showed if you are trying to get an exact match.  Consider 
the following:

%%%%
\version "2.19.82"

#(set-global-staff-size 14)

#(define (defaultpaper-text-font-size)
  (module-ref
    (ly:output-def-scope (ly:parser-lookup '$defaultpaper))
    'text-font-size))

#(define (abs->font-size size)
  (magnification->font-size
    (/ size (defaultpaper-text-font-size))))

\score {
  <<
    \new Staff {
      b'4^\markup { "qxb" \abs-fontsize #12 "qxb" }
    }
    \new Lyrics \lyricmode {
      \markup { "qxb" \abs-fontsize #20 "qxb" } 4
    }
  >>

  \layout {
    \context {
      \Staff
      \override TextScript.font-size = #(abs->font-size 12)
    }
    \context {
      \Lyrics
      \override LyricText.font-size = #(abs->font-size 20)
    }
  }
}
%%%%

You should see identically sized "qxb" text even when you change the 
global staff size.

NOTE: Manual use of things like make-pango-font-tree introduce the 
possibility that text-font-size is not an accurate value.  Providing one 
is following the recommended practice of setting the scaling factor, 
then things should work.

Also NOTE: Setting the fontSize context property will impact the 
results, since that applies in addition to the font-size property of a 
grob.


-- Aaron Hill