4 texidoc = "Use @code{define-event-class}, scheme engraver methods,
5 and grob creation methods to create a fully functional text spanner
9 #(define-event-class 'scheme-text-span-event 'span-event)
11 #(define (add-grob-definition grob-name grob-entry)
12 (let* ((meta-entry (assoc-get 'meta grob-entry))
13 (class (assoc-get 'class meta-entry))
14 (ifaces-entry (assoc-get 'interfaces meta-entry)))
15 (set-object-property! grob-name 'translation-type? list?)
16 (set-object-property! grob-name 'is-grob? #t)
17 (set! ifaces-entry (append (case class
18 ((Item) '(item-interface))
19 ((Spanner) '(spanner-interface))
20 ((Paper_column) '((item-interface
21 paper-column-interface)))
22 ((System) '((system-interface
24 (else '(unknown-interface)))
26 (set! ifaces-entry (uniq-list (sort ifaces-entry symbol<?)))
27 (set! ifaces-entry (cons 'grob-interface ifaces-entry))
28 (set! meta-entry (assoc-set! meta-entry 'name grob-name))
29 (set! meta-entry (assoc-set! meta-entry 'interfaces
31 (set! grob-entry (assoc-set! grob-entry 'meta meta-entry))
32 (set! all-grob-descriptions
33 (cons (cons grob-name grob-entry)
34 all-grob-descriptions))))
39 (bound-details . ((left . ((Y . 0)
43 (left-broken . ((end-on-note . #t)))
52 (left-bound-info . ,ly:line-spanner::calc-left-bound-info)
53 (outside-staff-priority . 350)
54 (right-bound-info . ,ly:line-spanner::calc-right-bound-info)
56 (stencil . ,ly:line-spanner::print)
59 (meta . ((class . Spanner)
60 (interfaces . (font-interface
62 line-spanner-interface
63 side-position-interface))))))
65 #(define scheme-event-spanner-types
68 . ((description . "Used to signal where scheme text spanner brackets
70 (types . (general-music scheme-text-span-event span-event event))
75 scheme-event-spanner-types
77 (set-object-property! (car x)
79 (cdr (assq 'description (cdr x))))
81 (set! lst (assoc-set! lst 'name (car x)))
82 (set! lst (assq-remove! lst 'description))
83 (hashq-set! music-name-to-property-table (car x) lst)
85 scheme-event-spanner-types))
87 #(set! music-descriptions
88 (append scheme-event-spanner-types music-descriptions))
90 #(set! music-descriptions
91 (sort music-descriptions alist<?))
93 #(define (add-bound-item spanner item)
94 (if (null? (ly:spanner-bound spanner LEFT))
95 (ly:spanner-set-bound! spanner LEFT item)
96 (ly:spanner-set-bound! spanner RIGHT item)))
98 #(define (axis-offset-symbol axis)
99 (if (eq? axis X) 'X-offset 'Y-offset))
101 #(define (set-axis! grob axis)
102 (if (not (number? (ly:grob-property grob 'side-axis)))
104 (set! (ly:grob-property grob 'side-axis) axis)
105 (ly:grob-chain-callback
108 ly:side-position-interface::x-aligned-side
109 side-position-interface::y-aligned-side)
110 (axis-offset-symbol axis)))))
112 schemeTextSpannerEngraver =
119 (listeners ((scheme-text-span-event engraver event)
120 (if (= START (ly:event-property event 'span-direction))
121 (set! event-start event)
122 (set! event-stop event))))
123 (acknowledgers ((note-column-interface engraver grob source-engraver)
124 (if (ly:spanner? span)
126 (ly:pointer-group-interface::add-grob span 'note-columns grob)
127 (add-bound-item span grob)))
128 (if (ly:spanner? finished)
130 (ly:pointer-group-interface::add-grob finished 'note-columns grob)
131 (add-bound-item finished grob)))))
132 ((process-music trans)
133 (if (ly:stream-event? event-stop)
135 (ly:warning "You're trying to end a scheme text spanner but you haven't started one.")
136 (begin (set! finished span)
137 (ly:engraver-announce-end-grob trans finished event-start)
139 (set! event-stop '()))))
140 (if (ly:stream-event? event-start)
141 (begin (set! span (ly:engraver-make-grob trans 'SchemeTextSpanner event-start))
143 (set! event-start '()))))
144 ((stop-translation-timestep trans)
145 (if (and (ly:spanner? span)
146 (null? (ly:spanner-bound span LEFT)))
147 (set! (ly:spanner-bound span LEFT)
148 (ly:context-property context 'currentMusicalColumn)))
149 (if (ly:spanner? finished)
151 (if (null? (ly:spanner-bound finished RIGHT))
152 (set! (ly:spanner-bound finished RIGHT)
153 (ly:context-property context 'currentMusicalColumn)))
155 (set! event-start '())
156 (set! event-stop '()))))
158 (if (ly:spanner? finished)
160 (if (null? (ly:spanner-bound finished RIGHT))
161 (set! (ly:spanner-bound finished RIGHT)
162 (ly:context-property context 'currentMusicalColumn)))
163 (set! finished '())))
164 (if (ly:spanner? span)
166 (ly:warning "I think there's a dangling scheme text spanner :-(")
167 (ly:grob-suicide! span)
168 (set! span '())))))))
170 schemeTextSpannerStart =
171 #(make-span-event 'SchemeTextSpanEvent START)
173 schemeTextSpannerEnd =
174 #(make-span-event 'SchemeTextSpanEvent STOP)
179 \grobdescriptions #all-grob-descriptions
183 \consists \schemeTextSpannerEngraver
188 a4 b\schemeTextSpannerStart c d |
189 \repeat unfold 20 { a4 b c d | }
190 a4 b c\schemeTextSpannerEnd d |
191 \override SchemeTextSpanner.to-barline = ##t
192 a4\schemeTextSpannerStart b d c |
193 \repeat unfold 20 { a4 b c d | }
194 a1\schemeTextSpannerEnd |