Changing properties for individual grobs

The \applyOutput command allows the tuning of any layout object, in any context. It requires a Scheme function with three arguments.

In the example below, function mc-squared is executed for all NoteHead grobs (within the current Voice context) at the current time step; the function modifies the grob's stencil, using the staff-position property to replace some pitches with markup.

See the ‘Extending’ manual for more information.

\version "2.24"

#(define (mc-squared grob grob-origin context)
   (let ((sp (ly:grob-property grob 'staff-position)))
     (ly:grob-set-property!
      grob 'stencil
      (grob-interpret-markup grob
       #{ \markup \lower #0.5
           #(case sp
              ((-5) "m")
              ((-3) "c ")
              ((-2) #{ \markup \teeny \bold 2 #})
              (else "bla")) #}))))

\relative c' {
  <d f g b>2
  \applyOutput Voice.NoteHead #mc-squared
  <d f g b>2
}