Re: How apply \magnifyStaff to full StaffGroup?

[Tina Petzel]

Hej all,

> On Tue, Mar 24, 2026, 11:36 AM Kieren MacMillan 
<kie...@kierenmacmillan.info>
> 
> wrote:
> > Hi all,
> > 
> > > Looking at the code for \magnifyStaff, there doesn't seem to be a way
> > > to apply it at the StaffGroup level.  So I think you're stuck with
> > > including the \with {} expression for each staff in the StaffGroup, as
> > > Mats shows in his file.
> > > 
> > > Fixing this would require a serious rewrite of \magnifyStaff.
> > 
> > What about that “hack” that Lukas gave me for “forcing” a command into a
> > different context?
> > Could that be applied to \magnifyStaff?
> 
> I don't think so, because \magnifyStaff doesn't set context properties.
> Rather, it directly modifies the data structures.  But I might be wrong.
> 
> Carl

Actually only requires a slight modification:


%%%
magnifyContext =
#(define-music-function (mag) (positive-number?)
   (_i "Change the staff size by factor @var{mag}.

This adjusts notation size and horizontal spacing automatically.")

   ;; these props are NOT allowed to shrink below default size
   (define unshrinkable-props
     '((StaffSymbol thickness)))

   ;; these props ARE allowed to shrink below default size
   (define shrinkable-props
     (let* ((baseline-skip-props
              (find-named-props 'baseline-skip all-grob-descriptions))
            (word-space-props
              (find-named-props 'word-space all-grob-descriptions))
            (space-alist-props
              (find-named-props 'space-alist all-grob-descriptions)))
       (append
         baseline-skip-props
         word-space-props
         space-alist-props
         '(
           ;; override at the 'Score level
           (SpacingSpanner spacing-increment)

           (StaffSymbol staff-space)
           (BarLine kern)
           (BarLine segno-kern)
           (BarLine hair-thickness)
           (BarLine thick-thickness)
           (Stem beamlet-default-length)
           (Stem double-stem-separation)
           ))))

   #{
     \stopStaff

     %% revert settings from last time
     %% (but only if \magnifyStaff has already been used
     %% and the staff magnification is changing)
     #(revert-fontSize 'magnifyMusic mag)
     #(revert-props    'magnifyMusic mag (append unshrinkable-props
                                                 shrinkable-props))

     %% scale settings
     %% (but only if staff magnification is changing
     %% and does not equal 1)
     #(scale-fontSize 'magnifyMusic mag)
     #(scale-props    'magnifyMusic mag #f unshrinkable-props)
     #(scale-props    'magnifyMusic mag #t shrinkable-props)

     %% this might cause problems until Issue 3990 is fixed
     \newSpacingSection

     \startStaff
     \set Staff.magnifyStaffValue = #mag
   #})

\new StaffGroup \with {
  \magnifyContext #0.7
  fontSize = -2
} <<
  \new Staff { c }
  \new Staff { c }
>>
%%%

(although since we probably are only going to use this in \with block this 
could be reduced to:
%%%
magnifyContext =
#(define-music-function (mag) (positive-number?)
   (_i "Change the staff size by factor @var{mag}.

This adjusts notation size and horizontal spacing automatically.")

   ;; these props are NOT allowed to shrink below default size
   (define unshrinkable-props
     '((StaffSymbol thickness)))

   ;; these props ARE allowed to shrink below default size
   (define shrinkable-props
     (let* ((baseline-skip-props
              (find-named-props 'baseline-skip all-grob-descriptions))
            (word-space-props
              (find-named-props 'word-space all-grob-descriptions))
            (space-alist-props
              (find-named-props 'space-alist all-grob-descriptions)))
       (append
         baseline-skip-props
         word-space-props
         space-alist-props
         '(
           ;; override at the 'Score level
           (SpacingSpanner spacing-increment)

           (StaffSymbol staff-space)
           (BarLine kern)
           (BarLine segno-kern)
           (BarLine hair-thickness)
           (BarLine thick-thickness)
           (Stem beamlet-default-length)
           (Stem double-stem-separation)
           ))))

   #{
     %% scale settings
     #(scale-fontSize 'magnifyMusic mag)
     #(scale-props    'magnifyMusic mag #f unshrinkable-props)
     #(scale-props    'magnifyMusic mag #t shrinkable-props)
   #})

\new StaffGroup \with {
  \magnifyContext #0.7
  fontSize = -2
} <<
  \new Staff { c }
  \new Staff { c }
>>
%%%

The only reason why \magnifyStaff does not work on StaffGroup level is that the 
scale-* functions if called with `'magnifyStaff` will try to find the parent 
Staff 
context. With `'magnifyMusic` it uses the context it is called in, but 
\magnifyMusic explicitely calls things in \context Bottom and is designed as 
toggle on, add music argument, toggle off.

Cheers,
Tina

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