pseudoIndents for custom layouting

all_base_includes.ly

@@ -28,6 +28,7 @@
 \include "arrows_in_scores.ly"
 \include "swing_style.ly"
 \include "inline_score.ly"
+\include "custom_indentation.ily"
 
 % reset important variables
 LAYOUT = \layout { \generalLayout }

custom_indentation.ily

@@ -0,0 +1,135 @@
+% https://lsr.di.unimi.it/LSR/Snippet?id=1098
+%%%%%%%% HEADER %%%%%%%%
+%
+% this code was prompted by
+% https://lists.gnu.org/archive/html/lilypond-user/2019-07/msg00139.html
+% and offers a pseudoIndent hack suitable for general use
+
+% keywords:
+% indent short-indent indentation system line
+% mid-score temporarily arbitrary individual single just only once
+% coda margin
+% mouse's tale acrostic mesostic spine
+
+%%%%%%%% PSEUDOINDENT FUNCTIONS %%%%%%%%
+
+% these two functions are for indenting individual systems
+% - to left-indent a system, apply \pseudoIndent before the music continues
+% - \pseudoIndents is similar, but lets you also indent on the right
+% - both provide an option for changing that system's instrument names
+
+% N.B. these functions
+% - assume application to non-ragged lines (generally the default)
+% - include a manual \break to ensure application at line start
+% - misbehave if called more than once at the same line start
+
+% the parameters of the (full) pseudoIndents function are:
+% 1: name-tweaks
+%      usually omitted; accepts replacement \markup for instrument names
+%      as an ordered list; starred elements leave their i-names unchanged.
+% 2: left-indent
+%      additional left-indentation, in staff-space units; can be negative,
+%      but avoid a total indentation which implies (unsupported) stretching.
+% 3: right-indent
+%      amount of right-indentation, in staff-space units; can be negative.
+%      - not offered by the (reduced) pseudoIndent function
+
+
+pseudoIndents = % inline alternative to a new \score, also with right-indent
+#(define-music-function (name-tweaks left-indent right-indent)
+  ((markup-list? '()) number? number?)
+  (define (warn-stretched p1 p2) (ly:input-warning (*location*) (G_
+    " pseudoIndents ~s ~s is stretching staff; expect distorted layout") p1 p2))
+  (let* (
+    (narrowing (+ left-indent right-indent)) ; of staff implied by args
+
+    (set-staffsymbol! (lambda (staffsymbol-grob) ; change staff to new width
+      (let* (
+        (left-bound (ly:spanner-bound staffsymbol-grob LEFT))
+        (left-moment (ly:grob-property left-bound 'when))
+        (capo? (moment<=? left-moment ZERO-MOMENT)) ; in first system of score
+        (layout (ly:grob-layout staffsymbol-grob))
+        (lw (ly:output-def-lookup layout 'line-width)) ; debugging info
+        (indent (ly:output-def-lookup layout (if capo? 'indent 'short-indent)))
+        (old-stil (ly:staff-symbol::print staffsymbol-grob))
+        (staffsymbol-x-ext (ly:stencil-extent old-stil X))
+        ;; >=2.19.16's first system has old-stil already narrowed [2]
+        ;; compensate for this (ie being not pristine) when calculating
+        ;; - old leftmost-x (its value is needed when setting so-called 'width)
+        ;; - the new width and position (via local variable narrowing_)
+        (ss-t (ly:staff-symbol-line-thickness staffsymbol-grob))
+        (pristine? (<= 0 (car staffsymbol-x-ext) ss-t)) ; would expect half
+        (leftmost-x (+ indent (if pristine? 0 narrowing)))
+        (narrowing_ (if pristine? narrowing 0)) ; uses 0 if already narrowed
+        (old-width (+ (interval-length staffsymbol-x-ext) ss-t))
+        (new-width (- old-width narrowing_))
+        (new-rightmost-x (+ leftmost-x new-width)) ; and set! this immediately
+        (junk (ly:grob-set-property! staffsymbol-grob 'width new-rightmost-x))
+        (in-situ-stil (ly:staff-symbol::print staffsymbol-grob))
+        (new-stil (ly:stencil-translate-axis in-situ-stil narrowing_ X))
+       ;(new-stil (stencil-with-color new-stil red)) ; for when debugging
+        (new-x-ext (ly:stencil-extent new-stil X)))
+      (ly:grob-set-property! staffsymbol-grob 'stencil new-stil)
+      (ly:grob-set-property! staffsymbol-grob 'X-extent new-x-ext)
+      )))
+
+    (set-X-offset! (lambda (margin-grob) ; move grob across to line start
+      (let* (
+        (old (ly:grob-property-data margin-grob 'X-offset))
+        (new (lambda (grob) (+ (if (procedure? old) (old grob) old) narrowing))))
+      (ly:grob-set-property! margin-grob 'X-offset new))))
+
+    (tweak-text! (lambda (i-name-grob mkup) ; tweak both instrumentname texts
+      (if (and (markup? mkup) (not (string=? (markup->string mkup) "*")))
+      (begin
+        (ly:grob-set-property! i-name-grob 'long-text mkup)
+        (ly:grob-set-property! i-name-grob 'text mkup)
+        )))) ; else retain existing text
+
+    (install-narrowing (lambda (leftedge-grob) ; on staves, + adapt left margin
+      (let* (
+        (sys (ly:grob-system leftedge-grob))
+        (all-grobs (ly:grob-array->list (ly:grob-object sys 'all-elements)))
+        (grobs-named (lambda (name)
+          (filter (lambda (x) (eq? name (grob::name x))) all-grobs)))
+        (first-leftedge-grob (list-ref (grobs-named 'LeftEdge) 0))
+        (relsys-x-of (lambda (g) (ly:grob-relative-coordinate g sys X)))
+        (leftedge-x (relsys-x-of first-leftedge-grob))
+        (leftedged? (lambda (g) (= (relsys-x-of g) leftedge-x)))
+        (leftedged-ss (filter leftedged? (grobs-named 'StaffSymbol))))
+      (if (eq? leftedge-grob first-leftedge-grob) ; ignore other leftedges [1]
+       (begin
+         (for-each set-staffsymbol! leftedged-ss)
+         (for-each set-X-offset! (grobs-named 'SystemStartBar))
+         (for-each set-X-offset! (grobs-named 'InstrumentName))
+         (for-each tweak-text! (grobs-named 'InstrumentName) name-tweaks)
+       ))))))
+
+  (if (negative? narrowing) (warn-stretched left-indent right-indent))
+  #{ % and continue anyway
+    % ensure that these overrides are applied only at begin-of-line
+    \break % (but this does not exclude unsupported multiple application)
+    % give the spacing engine notice regarding the loss of width for music
+    \once \override Score.LeftEdge.X-extent = #(cons narrowing narrowing)
+    % discard line start region of staff and reassemble left-margin elements
+    \once \override Score.LeftEdge.after-line-breaking = #install-narrowing
+    % shift the system to partition the narrowing between left and right
+    \overrideProperty Score.NonMusicalPaperColumn.line-break-system-details
+    .X-offset #(- right-indent)
+    % prevent a leftmost barnumber entering a stretched staff
+    \once \override Score.BarNumber.horizon-padding = #(max 1 (- 1 narrowing))
+  #}))
+
+pseudoIndent = % for changing just left-indent
+#(define-music-function (name-tweaks left-indent)
+  ((markup-list? '()) number?)
+  #{
+    \pseudoIndents $name-tweaks $left-indent 0
+  #})
+
+% [1] versions <2.19.1 can have end-of-line leftedges too
+%     - these were eliminated in issue 3761
+% [2] versions >=2.19.16: the first system behaves differently from the rest
+%     - a side effect of issue 660 ?
+% [3] versions >=2.23.0: LeftEdge's position may well differ in Y (but not in X)
+%     - a side effect of issue 6084 ?