--- /dev/null
+% DO NOT EDIT this file manually; it is automatically
+% generated from Documentation/snippets/new
+% Make any changes in Documentation/snippets/new/
+% and then run scripts/auxiliar/makelsr.py
+%
+% This file is in the public domain.
+%% Note: this file works from version 2.15.35
+\version "2.15.35"
+
+\header {
+ lsrtags = "staff-notation, tweaks-and-overrides, contexts-and-engravers"
+ texidoc = "This file defines and demonstrates a scheme engraver that
+connects stems across staves. The stem length need not be specified, as
+the code takes care of the variable distance between noteheads and staves."
+ doctitle = "Stem cross staff engraver"
+} % begin verbatim
+
+
+%{
+ A new stem (referred to as span in the code) is created to connect the
+ original stems. The original stems are made transparent.
+
+ The span is created as a child of the "root" stem, that is the stem
+ connected to a notehead with the end that is not to be extended.
+
+ Both stem directions are supported. Connecting more than two stems is
+ possible.
+%}
+
+% Values are close enough to ignore the difference
+#(define (close-enough? x y)
+ (< (abs (- x y)) 0.0001))
+
+% Combine a list of extents
+#(define (extent-combine extents)
+ (if (pair? (cdr extents))
+ (interval-union (car extents) (extent-combine (cdr extents)))
+ (car extents)))
+
+% Check if the stem is connectable to the root
+#(define ((stem-connectable? ref root) stem)
+ ; The root is always connectable to itself
+ (or (eq? root stem)
+ (and
+ ; Horizontal positions of the stems must be almost the same
+ (close-enough? (car (ly:grob-extent root ref X))
+ (car (ly:grob-extent stem ref X)))
+ ; The stem must be in the direction away from the root's notehead
+ (positive? (* (ly:grob-property root 'direction)
+ (- (car (ly:grob-extent stem ref Y))
+ (car (ly:grob-extent root ref Y))))))))
+
+% Connect stems if we have at least one stems connectable to the root
+#(define (stem-span-stencil span)
+ (let* ((system (ly:grob-system span))
+ (root (ly:grob-parent span X))
+ (stems (filter (stem-connectable? system root)
+ (ly:grob-object span 'stems))))
+ (if (<= 2 (length stems))
+ (let* ((yextents (map (lambda (st)
+ (ly:grob-extent st system Y)) stems))
+ (yextent (extent-combine yextents))
+ (layout (ly:grob-layout root))
+ (blot (ly:output-def-lookup layout 'blot-diameter)))
+ ; Hide spanned stems
+ (map (lambda (st)
+ (set! (ly:grob-property st 'transparent) #t))
+ stems)
+ ; Draw a nice looking stem with rounded corners
+ (ly:round-filled-box (ly:grob-extent root root X) yextent blot))
+ ; Nothing to connect, don't draw the span
+ #f)))
+
+% Create a stem span as a child of the cross-staff stem (the root)
+#(define ((make-stem-span! stems trans) root)
+ (let ((span (ly:engraver-make-grob trans 'Stem '())))
+ (ly:grob-set-parent! span X root)
+ (set! (ly:grob-object span 'stems) stems)
+ ; Suppress positioning, the stem code is confused by this weird stem
+ (set! (ly:grob-property span 'X-offset) 0)
+ (set! (ly:grob-property span 'stencil) stem-span-stencil)))
+
+% Set cross-staff property of the stem to this function to connect it to
+% other stems automatically
+#(define (cross-staff-connect stem)
+ #t)
+
+% Check if automatic connecting of the stem was requested. Stems connected
+% to cross-staff beams are cross-staff, but they should not be connected to
+% other stems just because of that.
+#(define (stem-is-root? stem)
+ (eq? cross-staff-connect (ly:grob-property-data stem 'cross-staff)))
+
+% Create stem spans for cross-staff stems
+#(define (make-stem-spans! ctx stems trans)
+ ; Cannot do extensive checks here, just make sure there are at least
+ ; two stems at this musical moment
+ (if (<= 2 (length stems))
+ (let ((roots (filter stem-is-root? stems)))
+ (map (make-stem-span! stems trans) roots))))
+
+% Connect cross-staff stems to the stems above in the system
+#(define (Span_stem_engraver ctx)
+ (let ((stems '()))
+ (make-engraver
+ ; Record all stems for the given moment
+ (acknowledgers
+ ((stem-interface trans grob source)
+ (set! stems (cons grob stems))))
+ ; Process stems and reset the stem list to empty
+ ((process-acknowledged trans)
+ (make-stem-spans! ctx stems trans)
+ (set! stems '())))))
+
+crossStaff =
+#(define-music-function (parser location notes) (ly:music?) #{
+ \override Stem #'cross-staff = #cross-staff-connect
+ $notes
+ \revert Stem #'cross-staff
+#})
+
+\layout {
+ \context {
+ \StaffGroup
+ \consists #Span_stem_engraver
+ }
+}
+
+\parallelMusic #'(voiceA voiceB voiceC) {
+ % Bar 1 - durations, beams, flags
+ g'2 g'4 g'8 [ g'16 ] g'16 |
+ \crossStaff { c'2 c'4 c'8 [ c'16 ] c'16 } |
+ R1 |
+
+ % Bar 2 - direction
+ g'8 \stemDown g'8 \crossStaff g'8 \stemNeutral g'8 g'4 r4 |
+ \crossStaff { c'8 \stemDown c'8 } c'8 \stemNeutral c'8 r4 r4 |
+ c8 \stemDown c8 c8 \stemNeutral \crossStaff { c8 c4 c4 } |
+
+ % Bar 3 - multiple voice styles
+ << c''2 \\ \crossStaff d'2 \\ a'2 \\ \crossStaff f'2 >> g'2 |
+ << b'2 \\ c'2 \\ g'2 \\ e'2 >> << e'2 \\ \\ \crossStaff c'2 >> |
+ << \crossStaff b2 \\ c2 \\ \crossStaff g2 \\ e2 >> r2 |
+
+ % Bar 4 - grace notes
+ \grace g'8 a'2 \stemDown \crossStaff { \grace g'8 a'2 } \stemNeutral |
+ \grace c'8 d'2 \stemDown \grace c'8 d'2 \stemNeutral |
+ \crossStaff { \grace c8 d2 } \stemDown \grace c8 d2 \stemNeutral |
+
+ % Bar 5 - cross-staff beams
+ g'8 g'8 g'8 g'8 r2 |
+ s1 |
+ \crossStaff { c8 [ \change Staff=stafftwo c''8 ] }
+ \change Staff=staffthree c8 [ \change Staff=stafftwo c''8 ] r2 |
+}
+
+\score {
+ \new StaffGroup <<
+ \new Staff = "staffone" <<
+ \new Voice {
+ \autoBeamOff \voiceA
+ }
+ >>
+ \new Staff = "stafftwo" <<
+ \new Voice {
+ \autoBeamOff \voiceB
+ }
+ >>
+ \new Staff = "staffthree" <<
+ \new Voice {
+ \autoBeamOff \clef bass \voiceC
+ }
+ >>
+ >>
+ \layout { }
+}
projects / lilypond.git / blobdiff