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Spacing between adjacent non-musical items

Within a non-musical column, items are laid out in a specific order. For instance, with the set of items in the picture below, the default order places the breathing sign first, then the clef, then the bar line, the key cancellation and key signature, and finally the time signature (this is controlled by the BreakAlignment.break-align-orders property).

\relative {
  \key g \minor
  g'1
  \breathe
  \clef alto
  \time 6/8
  \key a \major
  aes4.
}

The distance between two adjacent items from the same non-musical column is controlled by the value of the space-alist property of the leftmost one of the two. space-alist has the form of an associative list mapping break-align symbols to (spacing-style . value) pairs. A breakable item’s break-align symbol is given by the value of its break-align-symbol property; standard choices are listed in break-alignment-interface. Spacing styles are listed in break-aligned-interface. Among the available options, only extra-space and minimum-space are relevant for tweaking the space between non-musical items. The difference is that extra-space measures the padding from the right of the first object to the left of the second object while minimum-space counts from the left of the first object. Thus, a way to move the bar line farther from the clef is:

\relative {
  \key g \minor
  g'1
  \override Staff.Clef.space-alist.staff-bar = #'(extra-space . 4)
  \breathe
  \clef alto
  \time 6/8
  \key a \major
  aes4.
}

space-alist settings, not limited to the two spacing styles described above, are also possible to override the spacing between different columns. However, this kind of spacing is flexible, and does not merely depend on the types of object involved but also their shapes. Methods specific to it are documented in the next section.

Selected Snippets

Separating key cancellations from key signature changes

By default, the accidentals used for key cancellations are placed adjacent to those for key signature changes. This behavior can be changed by overriding the break-align-orders property of the BreakAlignment grob.

The value of break-align-orders is a vector of length 3, with quoted lists of breakable items as elements. Each list describes the default order of prefatory matter at the end, in the middle, and at the beginning of a line, respectively. We are only interested in changing the behaviour in the middle of a line.

If you look up the definition of break-align-orders in LilyPond’s Internal Reference (see the BreakAlignment grob), you get the following order in the second element:

...
staff-bar
key-cancellation
key-signature
...

We want to change that, moving key-cancellation before staff-bar. To make this happen we use the grob-transformer function, which gives us access to the original vector as the second argument of the lambda function, here called orig (we don’t need the first argument, grob). We return a new vector, with unchanged first and last elements. For the middle element, we first remove key-cancellation from the list, then adding it again before staff-bar.

#(define (insert-before where what lst)
   (cond
    ((null? lst)           ; If the list is empty,
     (list what))          ; return a single-element list.
    ((eq? where (car lst)) ; If we find symbol `where`,
     (cons what lst))      ; insert `what` before curr. position.
    (else                  ; Otherwise keep building the list by
     (cons (car lst)       ; adding the current element and
                           ; recursing with the next element.
           (insert-before where what (cdr lst))))))

cancellationFirst =
\override Score.BreakAlignment.break-align-orders =
#(grob-transformer
  'break-align-orders
  (lambda (grob orig)
    (let* ((middle (vector-ref orig 1))
           (middle (delq 'key-cancellation middle))
           (middle (insert-before
                    'staff-bar 'key-cancellation middle)))
      (vector
       ;; end of line
       (vector-ref orig 0)
       ;; middle of line
       middle
       ;; beginning of line
       (vector-ref orig 2)))))

music = { \key es \major d'1 \bar "||"
          \key a \major d'1 }

{ <>^\markup "default"
  \music }

{ <>^\markup "cancellation first"
  \cancellationFirst
  \music }

\paper { tagline = ##f }

See also

Notation Reference: Using the break-alignable-interface.

Extending LilyPond: Association lists (alists).

Internals Reference: Break_align_engraver, BreakAlignGroup, BreakAlignment, break-alignable-interface, break-aligned-interface, break-alignment-interface.