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13 @node Changing defaults
14 @chapter Changing defaults
16 The purpose of LilyPond's design is to provide the finest quality
17 output by default. Nevertheless, it may happen that you need to
18 change this default layout. The layout is controlled through a large
19 number of @q{knobs and switches} collectively called @q{properties}.
20 A tutorial introduction to accessing and modifying these properties
21 can be found in the Learning Manual, see @rlearning{Tweaking output}.
22 This should be read first. This chapter covers similar ground, but
23 in a style more appropriate to a reference manual.
25 @cindex Internals Reference
27 The definitive description of the controls available for tuning can
28 be found in a separate document: @rinternalsnamed{Top,the Internals
29 Reference}. That manual lists all the variables, functions and
30 options available in LilyPond. It is written as a HTML document,
32 @c leave the @uref as one long line.
33 @uref{http://@/lilypond@/.org/@/doc/@/stable/@/Documentation/@/user/@/lilypond@/-internals/,on@/-line},
34 and is also included with the LilyPond documentation package.
36 Internally, LilyPond uses Scheme (a LISP dialect) to provide
37 infrastructure. Overriding layout decisions in effect accesses the
38 program internals, which requires Scheme input. Scheme elements are
39 introduced in a @code{.ly} file with the hash mark
40 @code{#}.@footnote{@rextend{Scheme tutorial}, contains a short tutorial
41 on entering numbers, lists, strings, and symbols in Scheme.}
45 * Interpretation contexts::
46 * Explaining the Internals Reference::
47 * Modifying properties::
48 * Useful concepts and properties::
50 * Using music functions::
54 @node Interpretation contexts
55 @section Interpretation contexts
57 This section describes what contexts are, and how to modify them.
60 * Contexts explained::
62 * Keeping contexts alive::
63 * Modifying context plug-ins::
64 * Changing context default settings::
65 * Defining new contexts::
72 @rlearning{Contexts and engravers}.
75 @file{ly/@/engraver@/-init@/.ly},
76 @file{ly/@/performer@/-init@/.ly}.
79 @rlsr{Contexts and engravers}.
82 @rinternals{Contexts},
83 @rinternals{Engravers and Performers}.
86 @node Contexts explained
87 @subsection Contexts explained
90 @c TODO Rethink and rewrite
92 >> > > - list of contexts: my *danger unmaintainable*
93 >> > > alarm just went off. I'm
95 I knew it would... And leaving out some of them is perfectly fine
97 I do think that a list like this, with the main contexts and a
99 description of what they do (perhaps also with a note about what
101 behavior is associated with each of them, but this may be
103 should be there, and then we could simply list the remaining ones
105 further explanation and with links to the IR.
108 @c TODO Improve layout, order and consistency of wording -td
110 @c TODO Add introduction which explains contexts in generality -td
112 @c TODO Describe propagation of property values -td
114 Contexts are arranged hierarchically:
117 * Score - the master of all contexts::
118 * Top-level contexts - staff containers::
119 * Intermediate-level contexts - staves::
120 * Bottom-level contexts - voices::
123 @node Score - the master of all contexts
124 @unnumberedsubsubsec Score - the master of all contexts
126 This is the top level notation context. No other context can
127 contain a Score context. By default the Score context handles
128 the administration of time signatures and makes sure that items
129 such as clefs, time signatures, and key-signatures are aligned
132 A Score context is instantiated implicitly when a
133 @code{\score @{@dots{}@}} or @code{\layout @{@dots{}@}} block is
134 processed, or explicitly when a @code{\new Score} command is
137 @node Top-level contexts - staff containers
138 @unnumberedsubsubsec Top-level contexts - staff containers
140 @strong{@emph{StaffGroup}}
142 Groups staves while adding a bracket on the left side, grouping
143 the staves together. The bar lines of the contained staves are
144 connected vertically. @code{StaffGroup} only consists of a collection
145 of staves, with a bracket in front and spanning bar lines.
147 @strong{@emph{ChoirStaff}}
149 Identical to @code{StaffGroup} except that the bar lines of the
150 contained staves are not connected vertically.
152 @strong{@emph{GrandStaff}}
154 A group of staves, with a brace on the left side, grouping the
155 staves together. The bar lines of the contained staves are
156 connected vertically.
158 @strong{@emph{PianoStaff}}
160 Just like @code{GrandStaff}, but with support for instrument names
161 to the left of each system.
163 @node Intermediate-level contexts - staves
164 @unnumberedsubsubsec Intermediate-level contexts - staves
166 @strong{@emph{Staff}}
168 Handles clefs, bar lines, keys, accidentals. It can contain
169 @code{Voice} contexts.
171 @strong{@emph{RhythmicStaff}}
173 Like @code{Staff} but for printing rhythms. Pitches are ignored;
174 the notes are printed on one line.
176 @strong{@emph{TabStaff}}
178 Context for generating tablature. By default lays the music
179 expression out as a guitar tablature, printed on six lines.
181 @strong{@emph{DrumStaff}}
183 Handles typesetting for percussion. Can contain @code{DrumVoice}
185 @strong{@emph{VaticanaStaff}}
187 Same as @code{Staff}, except that it is designed for typesetting
188 a piece in gregorian style.
190 @strong{@emph{MensuralStaff}}
192 Same as @code{Staff}, except that it is designed for typesetting
193 a piece in mensural style.
195 @node Bottom-level contexts - voices
196 @unnumberedsubsubsec Bottom-level contexts - voices
198 Voice-level contexts initialise certain properties and start
199 appropriate engravers. Being bottom-level contexts, they cannot
200 contain other contexts.
202 @strong{@emph{Voice}}
204 Corresponds to a voice on a staff. This context handles the
205 conversion of dynamic signs, stems, beams, super- and sub-scripts,
206 slurs, ties, and rests. You have to instantiate this explicitly
207 if you require multiple voices on the same staff.
209 @strong{@emph{VaticanaVoice}}
211 Same as @code{Voice}, except that it is designed for typesetting
212 a piece in gregorian style.
214 @strong{@emph{MensuralVoice}}
216 Same as @code{Voice}, with modifications for typesetting a piece in
219 @strong{@emph{Lyrics}}
221 Corresponds to a voice with lyrics. Handles the printing of a
222 single line of lyrics.
224 @strong{@emph{DrumVoice}}
226 The voice context used in a percussion staff.
228 @strong{@emph{FiguredBass}}
230 The context in which @code{BassFigure} objects are created from
231 input entered in @code{\figuremode} mode.
233 @strong{@emph{TabVoice}}
235 The voice context used within a @code{TabStaff} context. Usually
236 left to be created implicitly.
238 @strong{@emph{CueVoice}}
240 A voice context used to render notes of a reduced size, intended
241 primarily for adding cue notes to a staff, see @ref{Formatting
242 cue notes}. Usually left to be created implicitly.
244 @strong{@emph{ChordNames}}
246 Typesets chord names.
251 Then the following, which I don't know what to do with:
253 * GregorianTranscriptionVoice
254 * GregorianTranscriptionStaff
257 Engraves fretboards from chords. Not easy... Not
259 There is now some documentation on FretBoards in the NR, under
260 instrument-specific notation -- cds.
265 Hard coded entry point for LilyPond. Cannot be tuned.
267 Silently discards all musical information given to this
272 @node Creating contexts
273 @subsection Creating contexts
275 @c TODO \new Score and \score
276 @c TODO more complete descriptions rather than learning style
278 For scores with only one voice and one staff, contexts are
279 created automatically. For more complex scores, it is necessary to
280 create them by hand. There are three commands that do this.
285 The easiest command is @code{\new}, and it also the quickest to type.
286 It is prepended to a music expression, for example
290 @cindex Context, creating
293 \new @var{type} @var{music expression}
297 where @var{type} is a context name (like @code{Staff} or
298 @code{Voice}). This command creates a new context, and starts
299 interpreting the @var{music expression} with that.
301 A practical application of @code{\new} is a score with many
302 staves. Each part that should be on its own staff, is preceded with
305 @lilypond[quote,verbatim,relative=2,ragged-right,fragment]
312 The @code{\new} command may also give a name to the context,
315 \new @var{type} = @var{id} @var{music}
317 However, this user specified name is only used if there is no other
318 context already earlier with the same name.
324 Like @code{\new}, the @code{\context} command also directs a music
325 expression to a context object, but gives the context an explicit name. The
329 \context @var{type} = @var{id} @var{music}
332 This form will search for an existing context of type @var{type}
333 called @var{id}. If that context does not exist yet, a new
334 context with the specified name is created. This is useful if
335 the context is referred to later on. For example, when
336 setting lyrics the melody is in a named context
339 \context Voice = "@b{tenor}" @var{music}
343 so the texts can be properly aligned to its notes,
346 \new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
351 Another possible use of named contexts is funneling two different
352 music expressions into one context. In the following example,
353 articulations and notes are entered separately,
357 arts = @{ s4-. s4-> @}
360 They are combined by sending both to the same @code{Voice} context,
364 \new Staff \context Voice = "A" \music
365 \context Voice = "A" \arts
368 @lilypond[quote,ragged-right]
372 \new Staff \context Voice = "A" \music
373 \context Voice = "A" \arts
377 With this mechanism, it is possible to define an Urtext (original
378 edition), with the option to put several distinct articulations on the
381 @cindex creating contexts
384 The third command for creating contexts is
386 \context @var{type} @var{music}
391 This is similar to @code{\context} with @code{= @var{id}}, but matches
392 any context of type @var{type}, regardless of its given name.
394 This variant is used with music expressions that can be interpreted at
395 several levels. For example, the @code{\applyOutput} command (see
396 @rextend{Running a function on all layout objects}). Without an explicit
397 @code{\context}, it is usually applied to @code{Voice}
400 \applyOutput #'@var{context} #@var{function} % apply to Voice
403 To have it interpreted at the @code{Score} or @code{Staff} level use
407 \applyOutput #'Score #@var{function}
408 \applyOutput #'Staff #@var{function}
413 @node Keeping contexts alive
414 @subsection Keeping contexts alive
416 @cindex contexts, keeping alive
417 @cindex contexts, lifetime
419 Contexts are usually terminated at the first musical moment in
420 which they have nothing to do. So @code{Voice} contexts die as
421 soon as they contain no events; @code{Staff} contexts die as soon
422 as all the @code{Voice} contexts within them contain no events; etc.
423 This can cause difficulties if earlier contexts which have died
424 have to be referenced, for example, when changing staves with
425 @code{\change} commands, associating lyrics with a voice with
426 @code{\lyricsto} commands, or when adding further musical events to
429 There is an exception to this general rule: just one of the
430 @code{Voice} contexts in a @code{Staff} context or in a
431 @code{<<...>>} construct will always persist to the end of the
432 enclosing @code{Staff} context or @code{<<...>>} construct, even
433 though there may be periods when it has nothing to do. The context
434 to persist in this way will be the first one encountered in the
435 first enclosed @code{@{...@}} construct, ignoring any in enclosed
436 @code{<<...>>} constructs.
438 Any context can be kept alive by ensuring it has something to do at
439 every musical moment. @code{Staff} contexts are kept alive by
440 ensuring one of their voices is kept alive. One way of doing this
441 is to add spacer rests to a voice in parallel with the real music.
442 These need to be added to every @code{Voice} context which needs to
443 be kept alive. If several voices are to be used sporadically it is
444 safest to keep them all alive rather than attempting to rely on the
445 exceptions mentioned above.
447 In the following example, both voice A and voice B are kept alive
448 in this way for the duration of the piece:
450 @lilypond[quote,verbatim]
451 musicA = \relative c'' { d4 d d d }
452 musicB = \relative c'' { g4 g g g }
455 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
456 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
461 \context Voice = "A" {
465 \context Voice = "B" {
469 \context Voice = "A" { \musicA }
470 \context Voice = "B" { \musicB }
471 \context Voice = "A" { \musicA }
482 @cindex lyrics, aligning with sporadic melody
484 The following example shows how a sporadic melody line with lyrics
485 might be written using this approach. In a real situation the
486 melody and accompaniment would consist of several different
489 @lilypond[quote,verbatim]
490 melody = \relative c'' { a4 a a a }
491 accompaniment = \relative c' { d4 d d d }
492 words = \lyricmode { These words fol -- low the mel -- o -- dy }
495 \new Staff = "music" {
497 \new Voice = "melody" {
499 s1*4 % Keep Voice "melody" alive for 4 bars
502 \new Voice = "accompaniment" {
507 \context Voice = "melody" { \melody }
508 \context Voice = "accompaniment" { \accompaniment }
510 \context Voice = "accompaniment" { \accompaniment }
512 \context Voice = "melody" { \melody }
513 \context Voice = "accompaniment" { \accompaniment }
518 \new Lyrics \with { alignAboveContext = #"music" }
519 \lyricsto "melody" { \words }
524 An alternative way, which may be better in many circumstances, is
525 to keep the melody line alive by simply including spacer notes to
526 line it up correctly with the accompaniment:
528 @lilypond[quote,verbatim]
529 melody = \relative c'' {
535 accompaniment = \relative c' {
541 words = \lyricmode { These words fol -- low the mel -- o -- dy }
545 \new Staff = "music" {
547 \new Voice = "melody" {
551 \new Voice = "accompaniment" {
557 \new Lyrics \with { alignAboveContext = #"music" }
558 \lyricsto "melody" { \words }
564 @node Modifying context plug-ins
565 @subsection Modifying context plug-ins
567 @c TODO Should this be Modifying engravers or Modifying contexts?
569 Notation contexts (like @code{Score} and @code{Staff}) not only
571 they also contain plug-ins called @q{engravers} that create notation
572 elements. For example, the @code{Voice} context contains a
573 @code{Note_head_engraver} and the @code{Staff} context contains a
574 @code{Key_signature_engraver}.
576 For a full a description of each plug-in, see
578 @rinternals{Engravers and Performers}.
581 Internals Reference @expansion{} Translation @expansion{} Engravers.
583 Every context described in
585 @rinternals{Contexts}
588 Internals Reference @expansion{} Translation @expansion{} Context.
590 lists the engravers used for that context.
593 It can be useful to shuffle around these plug-ins. This is done by
594 starting a new context with @code{\new} or @code{\context}, and
600 \new @var{context} \with @{
613 where the @dots{} should be the name of an engraver. Here is a simple
614 example which removes @code{Time_signature_engraver} and
615 @code{Clef_engraver} from a @code{Staff} context,
617 @lilypond[quote,relative=1,verbatim,fragment]
623 \remove "Time_signature_engraver"
624 \remove "Clef_engraver"
631 In the second staff there are no time signature or clef symbols. This
632 is a rather crude method of making objects disappear since it will affect
633 the entire staff. This method also influences the spacing, which may or
634 may not be desirable. More sophisticated methods of blanking objects
635 are shown in @rlearning{Visibility and color of objects}.
637 The next example shows a practical application. Bar lines and time
638 signatures are normally synchronized across the score. This is done
639 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
640 This plug-in keeps an administration of time signature, location
641 within the measure, etc. By moving these engraver from @code{Score} to
642 @code{Staff} context, we can have a score where each staff has its own
645 @cindex polymetric scores
646 @cindex Time signatures, multiple
648 @lilypond[quote,verbatim]
652 \consists "Timing_translator"
653 \consists "Default_bar_line_engraver"
659 \consists "Timing_translator"
660 \consists "Default_bar_line_engraver"
669 \remove "Timing_translator"
670 \remove "Default_bar_line_engraver"
678 Usually the order in which the engravers are specified
679 does not matter, but in a few special cases the order
680 is important, for example where one engraver writes
681 a property and another reads it, or where one engraver
682 creates a grob and another must process it. The order in
683 which the engravers are specified is the order in which
684 they are called to carry out their processing.
686 The following orderings are important: the
687 @code{Bar_engraver} must normally be first, and
688 the @code{New_fingering_engraver} must come before
689 the @code{Script_column_engraver}. There may be others
690 with ordering dependencies.
692 @node Changing context default settings
693 @subsection Changing context default settings
695 The context settings which are to be used by default in
696 @code{Score}, @code{Staff} and @code{Voice} contexts may be specified
697 in a @code{\layout} block, as illustrated in the following example.
698 The @code{\layout} block should be placed within the @code{\score}
699 block to which it is to apply, but outside any music.
701 Note that the @code{\set} command itself and the context must be
702 omitted when the context default values are specified in this way:
704 @lilypond[quote,verbatim]
707 a4^"Really small, thicker stems, no time signature" a a a
714 \override Stem #'thickness = #4.0
715 \remove "Time_signature_engraver"
721 In this example, the @code{\Staff} command specifies that the
722 subsequent specifications are to be applied to all staves within
725 Modifications can be made to the @code{Score} context or all
726 @code{Voice} contexts in a similar way.
730 It is not possible to collect context changes in a variable and apply
731 them to a @code{\context} definition by referring to that variable.
733 The @code{\RemoveEmptyStaffContext} will overwrite your current
734 @code{\Staff} settings. If you wish to change the defaults for a
735 staff which uses @code{\RemoveEmptyStaffContext}, you must do so
736 after calling @code{\RemoveEmptyStaffContext}, ie
741 \RemoveEmptyStaffContext
743 \override Stem #'thickness = #4.0
748 @c TODO: add \with in here.
752 @node Defining new contexts
753 @subsection Defining new contexts
755 @cindex contexts, defining new
756 @cindex engravers, including in contexts
771 Specific contexts, like @code{Staff} and @code{Voice}, are made of
772 simple building blocks. It is possible to create new types of
773 contexts with different combinations of engraver plug-ins.
775 The next example shows how to build a different type of
776 @code{Voice} context from scratch. It will be similar to
777 @code{Voice}, but only prints centered slash note heads. It can be used
778 to indicate improvisation in jazz pieces,
780 @lilypond[quote,ragged-right]
783 \type "Engraver_group"
784 \consists "Note_heads_engraver"
785 \consists "Rhythmic_column_engraver"
786 \consists "Text_engraver"
787 \consists Pitch_squash_engraver
788 squashedPosition = #0
789 \override NoteHead #'style = #'slash
790 \override Stem #'transparent = ##t
794 \accepts "ImproVoice"
798 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
799 c4 c^"undress" c_"while playing :)" c }
805 These settings are defined within a @code{\context} block inside a
806 @code{\layout} block,
816 In the following discussion, the example input shown should go in place
817 of the @dots{} in the previous fragment.
819 First it is necessary to define a name for the new context:
825 Since it is similar to the @code{Voice}, we want commands that work
826 on (existing) @code{Voice}s to remain working. This is achieved by
827 giving the new context an alias @code{Voice},
833 The context will print notes and instructive texts, so we need to add
834 the engravers which provide this functionality,
837 \consists Note_heads_engraver
838 \consists Text_engraver
841 but we only need this on the center line,
844 \consists Pitch_squash_engraver
845 squashedPosition = #0
848 The @rinternals{Pitch_squash_engraver} modifies note heads (created
849 by @rinternals{Note_heads_engraver}) and sets their vertical
850 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
853 The notes look like a slash, and have no stem,
856 \override NoteHead #'style = #'slash
857 \override Stem #'transparent = ##t
860 All these plug-ins have to cooperate, and this is achieved with a
861 special plug-in, which must be marked with the keyword @code{\type}.
862 This should always be @code{Engraver_group}.
865 \type "Engraver_group"
873 \type "Engraver_group"
874 \consists "Note_heads_engraver"
875 \consists "Text_engraver"
876 \consists Pitch_squash_engraver
877 squashedPosition = #0
878 \override NoteHead #'style = #'slash
879 \override Stem #'transparent = ##t
885 Contexts form hierarchies. We want to hang the @code{ImproVoice}
886 under @code{Staff}, just like normal @code{Voice}s. Therefore, we
887 modify the @code{Staff} definition with the @code{\accepts}
898 The opposite of @code{\accepts} is @code{\denies},
899 which is sometimes needed when reusing existing context definitions.
901 Putting both into a @code{\layout} block, like
911 \accepts "ImproVoice"
916 Then the output at the start of this subsection can be entered as
924 c c_"while playing :)"
931 @node Aligning contexts
932 @subsection Aligning contexts
934 New contexts may be aligned above or below existing contexts. This
935 could be useful in setting up a vocal staff (@rlearning{Vocal ensembles}) and
938 @c TODO Better example needed. Ref LM, and expand on it.
941 @funindex alignAboveContext
942 @funindex alignBelowContext
944 @lilypond[quote,ragged-right]
947 \relative c' \new Staff = "main" {
950 \new Staff \with { alignAboveContext = #"main" } \ossia
957 @cindex nested contexts
958 @cindex contexts, nested
963 Contexts like @code{PianoStaff} can contain other contexts
964 nested within them. Contexts which are acceptable for nesting
965 are defined by the @qq{accepts} list of a context. Contexts
966 which are not in this list are placed below the outer context
967 in the printed score.
968 For example, the @code{PianoStaff} context is defined by default
969 to accept @code{Staff} and @code{FiguredBass} contexts within
970 it, but not (for example) a @code{Lyrics} context. So in the
971 following structure the lyrics are placed below the piano staff
972 rather than between the two staves:
974 @lilypond[verbatim,quote,relative=1]
977 \new Staff { e4 d c2 }
978 \addlyrics { Three blind mice }
986 The @qq{accepts} list of a context can be modified to include
987 additional nested contexts, so if we wanted the lyrics to appear
988 between the two staves we could use:
990 @lilypond[verbatim,quote,relative=1]
991 \new PianoStaff \with { \accepts Lyrics }
993 \new Staff { e4 d c2 }
994 \addlyrics { Three blind mice }
1002 The opposite of @code{\accepts} is @code{\denies}; this removes a
1003 context from the @qq{accepts} list.
1005 @node Explaining the Internals Reference
1006 @section Explaining the Internals Reference
1010 * Navigating the program reference::
1011 * Layout interfaces::
1012 * Determining the grob property::
1013 * Naming conventions::
1016 @node Navigating the program reference
1017 @subsection Navigating the program reference
1019 @c TODO remove this (it's in the LM)
1020 @c Replace with more factual directions
1022 Suppose we want to move the fingering indication in the fragment
1025 @lilypond[quote,fragment,relative=2,verbatim]
1031 If you visit the documentation on fingering instructions (in
1032 @ref{Fingering instructions}), you will notice:
1037 Internals Reference: @rinternals{Fingering}.
1042 @c outdated info; probably will delete.
1044 This fragment points to two parts of the program reference: a page
1045 on @code{FingeringEvent} and one on @code{Fingering}.
1047 The page on @code{FingeringEvent} describes the properties of the music
1048 expression for the input @code{-2}. The page contains many links
1049 forward. For example, it says
1052 Accepted by: @rinternals{Fingering_engraver},
1056 That link brings us to the documentation for the Engraver, the
1060 This engraver creates the following layout objects: @rinternals{Fingering}.
1063 In other words, once the @code{FingeringEvent}s are interpreted, the
1064 @code{Fingering_engraver} plug-in will process them.
1068 @c I can't figure out what this is supposed to mean. -gp
1070 The @code{Fingering_engraver} is also listed to create
1071 @rinternals{Fingering} objects,
1073 @c old info? it doesn't make any sense to me with our current docs.
1075 second bit of information listed under @b{See also} in the Notation
1080 The programmer's reference is available as an HTML document. It is
1081 highly recommended that you read it in HTML form, either online or
1082 by downloading the HTML documentation. This section will be much more
1083 difficult to understand if you are using the
1087 Follow the link to @rinternals{Fingering}. At the top of the
1091 Fingering objects are created by: @rinternals{Fingering_engraver} and
1092 @rinternals{New_fingering_engraver}.
1095 By following related links inside the program reference, we can follow the
1096 flow of information within the program:
1100 @item @rinternals{Fingering}:
1101 @rinternals{Fingering} objects are created by:
1102 @rinternals{Fingering_engraver}
1104 @item @rinternals{Fingering_engraver}:
1105 Music types accepted: @rinternals{fingering-event}
1107 @item @rinternals{fingering-event}:
1108 Music event type @code{fingering-event} is in Music expressions named
1109 @rinternals{FingeringEvent}
1112 This path goes against the flow of information in the program: it
1113 starts from the output, and ends at the input event. You could
1114 also start at an input event, and read with the flow of
1115 information, eventually ending up at the output object(s).
1117 The program reference can also be browsed like a normal document. It
1118 contains chapters on
1120 @rinternals{Music definitions},
1123 @code{Music definitions}
1125 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1126 chapter lists all the definitions used and all properties that may be
1130 @node Layout interfaces
1131 @subsection Layout interfaces
1133 @cindex interface, layout
1134 @cindex layout interface
1137 The HTML page that we found in the previous section describes the
1138 layout object called @rinternals{Fingering}. Such an object is a
1139 symbol within the score. It has properties that store numbers (like
1140 thicknesses and directions), but also pointers to related objects. A
1141 layout object is also called a @emph{Grob}, which is short for Graphical
1142 Object. For more details about Grobs, see @rinternals{grob-interface}.
1144 The page for @code{Fingering} lists the definitions for the
1145 @code{Fingering} object. For example, the page says
1148 @code{padding} (dimension, in staff space):
1154 which means that the number will be kept at a distance of at least 0.5
1158 Each layout object may have several functions as a notational or
1159 typographical element. For example, the Fingering object
1160 has the following aspects
1164 Its size is independent of the horizontal spacing, unlike slurs or beams.
1167 It is a piece of text. Granted, it is usually a very short text.
1170 That piece of text is typeset with a font, unlike slurs or beams.
1173 Horizontally, the center of the symbol should be aligned to the
1174 center of the note head.
1177 Vertically, the symbol is placed next to the note and the staff.
1180 The vertical position is also coordinated with other superscript
1181 and subscript symbols.
1184 Each of these aspects is captured in so-called @emph{interface}s,
1185 which are listed on the @rinternals{Fingering} page at the bottom
1188 This object supports the following interfaces:
1189 @rinternals{item-interface},
1190 @rinternals{self-alignment-interface},
1191 @rinternals{side-position-interface}, @rinternals{text-interface},
1192 @rinternals{text-script-interface}, @rinternals{font-interface},
1193 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1196 Clicking any of the links will take you to the page of the respective
1197 object interface. Each interface has a number of properties. Some of
1198 them are not user-serviceable (@q{Internal properties}), but others
1201 We have been talking of @emph{the} @code{Fingering} object, but actually it
1202 does not amount to much. The initialization file (see
1203 @rlearning{Other sources of information})
1204 @file{scm/@/define@/-grobs@/.scm} shows the soul of the @q{object},
1209 (avoid-slur . around)
1210 (slur-padding . 0.2)
1211 (staff-padding . 0.5)
1212 (self-alignment-X . 0)
1213 (self-alignment-Y . 0)
1214 (script-priority . 100)
1215 (stencil . ,ly:text-interface::print)
1216 (direction . ,ly:script-interface::calc-direction)
1217 (font-encoding . fetaNumber)
1218 (font-size . -5) ; don't overlap when next to heads.
1219 (meta . ((class . Item)
1220 (interfaces . (finger-interface
1222 text-script-interface
1224 side-position-interface
1225 self-alignment-interface
1226 item-interface))))))
1230 As you can see, the @code{Fingering} object is nothing more than a
1231 bunch of variable settings, and the webpage in the Internals Reference
1232 is directly generated from this definition.
1235 @node Determining the grob property
1236 @subsection Determining the grob property
1238 @c TODO remove this (it's in the LM)
1239 @c Replace with more factual directions
1241 Recall that we wanted to change the position of the @b{2} in
1243 @lilypond[quote,fragment,relative=2,verbatim]
1249 Since the @b{2} is vertically positioned next to its note, we have to
1250 meddle with the interface associated with this positioning. This is
1251 done using @code{side-position-interface}. The page for this interface
1255 @code{side-position-interface}
1257 Position a victim object (this one) next to other objects (the
1258 support). The property @code{direction} signifies where to put the
1259 victim object relative to the support (left or right, up or down?)
1264 Below this description, the variable @code{padding} is described as
1269 (dimension, in staff space)
1271 Add this much extra space between objects that are next to each other.
1275 By increasing the value of @code{padding}, we can move the
1276 fingering away from the note head. The following command inserts
1277 3 staff spaces of white
1278 between the note and the fingering:
1280 \once \override Voice.Fingering #'padding = #3
1283 Inserting this command before the Fingering object is created,
1284 i.e., before @code{c2}, yields the following result:
1286 @lilypond[quote,relative=2,fragment,verbatim]
1287 \once \override Voice.Fingering #'padding = #3
1294 In this case, the context for this tweak is @code{Voice}. This
1295 fact can also be deduced from the program reference, for the page for
1296 the @rinternals{Fingering_engraver} plug-in says
1299 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1303 @node Naming conventions
1304 @subsection Naming conventions
1306 Another thing that is needed, is an overview of the various naming
1310 @item scheme functions: lowercase-with-hyphens (incl. one-word
1312 @item scheme functions: ly:plus-scheme-style
1313 @item music events, music classes and music properties:
1315 @item Grob interfaces: scheme-style
1316 @item backend properties: scheme-style (but X and Y!)
1317 @item contexts (and MusicExpressions and grobs): Capitalized or
1319 @item context properties: lowercaseFollowedByCamelCase
1321 Capitalized_followed_by_lowercase_and_with_underscores
1324 Questions to be answered:
1326 @item Which of these are conventions and which are rules?
1327 @item Which are rules of the underlying language, and which are
1331 @node Modifying properties
1332 @section Modifying properties
1334 @c TODO change the menu and subsection node names to use
1335 @c backslash once the new macro to handle the refs
1336 @c is available. Need to find and change all refs at
1337 @c the same time. -td
1340 * Overview of modifying properties::
1342 * The override command::
1343 * The tweak command::
1344 * set versus override::
1348 @node Overview of modifying properties
1349 @subsection Overview of modifying properties
1351 Each context is responsible for creating certain types of graphical
1352 objects. The settings used for printing these objects are also stored by
1353 context. By changing these settings, the appearance of objects can be
1356 There are two different kinds of properties stored in contexts:
1357 context properties and grob properties. Context properties are
1358 properties that apply to the context as a whole and control
1359 how the context itself is displayed. In contrast, grob properties
1360 apply to specific grob types that will be displayed in the context.
1362 The @code{\set} and @code{\unset} commands are used to change values
1363 for context properties. The @code{\override} and @code{\revert}
1364 commands are used to change values for grob properties.
1367 The syntax for this is
1370 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1373 Here @var{name} is the name of a graphical object, like
1374 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1375 variable of the formatting system (@q{grob property} or @q{layout
1376 property}). The latter is a symbol, so it must be quoted. The
1377 subsection @ref{Modifying properties}, explains what to fill in
1378 for @var{name}, @var{property}, and @var{value}. Here we only
1379 discuss the functionality of this command.
1384 \override Staff.Stem #'thickness = #4.0
1388 makes stems thicker (the default is 1.3, with staff line thickness as a
1389 unit). Since the command specifies @code{Staff} as context, it only
1390 applies to the current staff. Other staves will keep their normal
1391 appearance. Here we see the command in action:
1393 @lilypond[quote,verbatim,relative=2,fragment]
1395 \override Staff.Stem #'thickness = #4.0
1401 The @code{\override} command changes the definition of the @code{Stem}
1402 within the current @code{Staff}. After the command is interpreted
1403 all stems are thickened.
1405 Analogous to @code{\set}, the @var{context} argument may be left out,
1406 causing the default context @code{Voice} to be used. Adding
1407 @code{\once} applies the change during one timestep only.
1409 @lilypond[quote,fragment,verbatim,relative=2]
1411 \once \override Stem #'thickness = #4.0
1416 The @code{\override} must be done before the object is
1417 started. Therefore, when altering @emph{Spanner} objects such as slurs
1418 or beams, the @code{\override} command must be executed at the moment
1419 when the object is created. In this example,
1421 @lilypond[quote,fragment,verbatim,relative=2]
1422 \override Slur #'thickness = #3.0
1424 \override Beam #'thickness = #0.6
1429 the slur is fatter but the beam is not. This is because the command for
1430 @code{Beam} comes after the Beam is started, so it has no effect.
1432 Analogous to @code{\unset}, the @code{\revert} command for a context
1433 undoes an @code{\override} command; like with @code{\unset}, it only
1434 affects settings that were made in the same context. In other words, the
1435 @code{\revert} in the next example does not do anything.
1438 \override Voice.Stem #'thickness = #4.0
1439 \revert Staff.Stem #'thickness
1442 Some tweakable options are called @q{subproperties} and reside inside
1443 properties. To tweak those, use commands of the form
1445 @c leave this as a long long
1447 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1454 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1461 @rinternals{Backend},
1462 @rinternals{All layout objects},
1463 @rinternals{OverrideProperty},
1464 @rinternals{RevertProperty},
1465 @rinternals{PropertySet}.
1470 The back-end is not very strict in type-checking object properties.
1471 Cyclic references in Scheme values for properties can cause hangs
1472 or crashes, or both.
1476 @node The set command
1477 @subsection The @code{@bs{}set} command
1481 @cindex changing properties
1483 Each context has a set of @emph{properties}, variables contained
1484 in that context. Context properties are changed with the @code{\set}
1485 command, which has the following syntax:
1488 \set @var{context}.@var{property} = #@var{value}
1491 @var{value} is a Scheme object, which is why it must be preceded by
1492 the @code{#} character.
1494 Contexts properties are usually named in
1495 @code{studlyCaps}. They mostly control the translation from
1496 music to notation, e.g. @code{localKeySignature} (for determining
1497 whether to print accidentals), or @code{measurePosition} (for
1498 determining when to print a bar line). Context properties can
1499 change value over time while interpreting a piece of music;
1500 @code{measurePosition} is an obvious example of
1501 this. Context properties are modified with @code{\set}.
1503 For example, multimeasure rests will be combined into a single bar
1504 if the context property @code{skipBars} is set to @code{#t}:
1506 @lilypond[quote,verbatim,relative=2,fragment]
1508 \set Score.skipBars = ##t
1512 If the @var{context} argument is left out, then the property will be
1513 set in the current bottom context (typically @code{ChordNames},
1514 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1516 @lilypond[quote,verbatim,relative=2,fragment]
1517 \set Score.autoBeaming = ##f
1521 \set autoBeaming = ##t
1529 The change is applied @q{on-the-fly}, during the music, so that the
1530 setting only affects the second group of eighth notes.
1532 Note that the bottom-most context does not always contain the property
1533 that you wish to change -- for example, attempting to set the
1534 @code{skipBars} property of the default bottom context, in this case
1535 @code{Voice}, will have no effect, because skipBars is a property of
1536 the @code{Score} context.
1538 @lilypond[quote,verbatim,relative=2,fragment]
1544 Contexts are hierarchical, so if an enclosing context was specified, for
1545 example @code{Staff}, then the change would also apply to all
1546 @code{Voice}s in the current staff.
1550 The @code{\unset} command:
1553 \unset @var{context}.@var{property}
1557 is used to remove the definition of @var{property} from
1558 @var{context}. This command removes
1559 the definition only if it is set in @var{context}.
1560 Properties that have been set in enclosing contexts will
1561 not be altered by an unset in an enclosed context:
1563 @lilypond[quote,verbatim,relative=2,fragment]
1564 \set Score.autoBeaming = ##t
1569 \unset Score.autoBeaming
1577 Like @code{\set}, the @var{context} argument does not have to be
1578 specified for a bottom context, so the two statements
1581 \set Voice.autoBeaming = ##t
1582 \set autoBeaming = ##t
1586 are equivalent if the current bottom context is @code{Voice}.
1590 Preceding a @code{\set} command by @code{\once} makes the
1591 setting apply to only a single time-step:
1593 @lilypond[quote,verbatim,relative=2,fragment]
1595 \once \set fontSize = #4.7
1600 A full description of all available context properties is in the
1601 internals reference, see
1603 @rinternals{Tunable context properties}.
1606 Translation @expansion{} Tunable context properties.
1611 Internals Reference:
1613 @rinternals{Tunable context properties}.
1616 @cindex grob properties
1617 @cindex properties, grob
1621 @node The override command
1622 @subsection The @code{\override} command
1624 There is a special type of context property: the grob
1625 description. Grob descriptions are named in @code{StudlyCaps}
1626 (starting with capital letters). They contain the
1627 @q{default settings} for a particular kind of grob as an
1628 association list. See @file{scm/@/define@/-grobs@/.scm}
1629 to see the settings for each grob description. Grob descriptions
1630 are modified with @code{\override}.
1632 @code{\override} is actually a shorthand;
1635 \override @var{context}.@var{GrobName} #'@var{property} = #@var{value}
1639 is more or less equivalent to
1641 @c leave this long line -gp
1643 \set @var{context}.@var{GrobName} =
1644 #(cons (cons '@var{property} @var{value})
1645 <previous value of @var{context}.@var{GrobName}>)
1648 The value of @code{context}.@code{GrobName} (the alist) is used to initialize
1649 the properties of individual grobs. Grobs have
1650 properties, named in Scheme style, with
1651 @code{dashed-words}. The values of grob properties change
1652 during the formatting process: formatting basically amounts
1653 to computing properties using callback functions.
1655 For example, we can increase the thickness of a note stem by
1656 overriding the @code{thickness} property of the @code{Stem}
1659 @lilypond[quote, verbatim, relative=2, fragment]
1661 \override Voice.Stem #'thickness = #3.0
1665 If no context is specified in an @code{\override}, the bottom
1668 @lilypond[quote, verbatim, relative=2, fragment]
1669 { \override Staff.Stem #'thickness = #3.0
1673 \override Stem #'thickness = #0.5
1683 @cindex reverting overrides
1684 @cindex overrides, reverting
1686 The effects of @code{\override} can be undone by @code{\revert}:
1688 @lilypond[quote, verbatim, relative=2, fragment]
1690 \override Voice.Stem #'thickness = #3.0
1692 \revert Voice.Stem #'thickness
1696 The effects of @code{\override} and @code{\revert} apply to all
1697 grobs in the affected context from the current time forward:
1699 @lilypond[quote, verbatim, relative=2, fragment]
1704 \override Staff.Stem #'thickness = #3.0
1708 \revert Staff.Stem #'thickness
1716 @cindex overriding for only one moment
1718 @code{\once} can be used with @code{\override}
1719 to affect only the current time step:
1721 @lilypond[quote, verbatim, relative=2, fragment]
1725 \override Stem #'thickness = #3.0
1729 \once \override Stem #'thickness = #3.0
1738 Commands which change output generally look like
1741 \override Voice.Stem #'thickness = #3.0
1745 To construct this tweak we must determine these bits of information:
1748 @item the context: here @code{Voice}.
1749 @item the layout object: here @code{Stem}.
1750 @item the layout property: here @code{thickness}.
1751 @item a sensible value: here @code{3.0}.
1754 Some tweakable options are called @q{subproperties} and reside inside
1755 properties. To tweak those, use commands in the form
1758 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1761 @cindex internal documentation
1762 @cindex finding graphical objects
1763 @cindex graphical object descriptions
1766 @cindex internal documentation
1768 For many properties, regardless of the data type of the property, setting the
1769 property to false ( @code{##f} ) will result in turning it off, causing
1770 LilyPond to ignore that property entirely. This is particularly useful for
1771 turning off grob properties which may otherwise be causing problems.
1773 We demonstrate how to glean this information from the notation manual
1774 and the program reference.
1779 Internals Reference:
1780 @rinternals{Backend}
1782 @node The tweak command
1783 @subsection The @code{\tweak} command
1788 Changing grob properties
1789 with @code{\override} causes the changes to apply to all of the
1790 given grobs in the context at the moment the change applies.
1791 Sometimes, however, it is desirable to have changes apply to just
1792 one grob, rather than to all grobs in the affected context. This is
1793 accomplished with the @code{\tweak} command, which has the following
1797 \tweak #'@code{grob-property} #@code{value}
1800 The @code{\tweak} command applies to the object that immediately
1801 follows @code{value} in the music stream.
1804 In some cases, it is possible to take a short-cut for tuning
1805 graphical objects. For objects that are created directly from
1806 an item in the input file, you can use the @code{\tweak} command.
1809 @lilypond[relative=2,verbatim,quote]
1814 \tweak #'duration-log #1
1817 -\tweak #'padding #8
1823 But the main use of the @code{\tweak} command is to modify just
1824 one of a number of notation elements which start at the same musical
1825 moment, like the notes of a chord, or tuplet brackets which start
1828 The @code{\tweak} command sets a property in the following object
1829 directly, without requiring the grob name or context to be
1830 specified. For this to work, it is necessary for the @code{\tweak}
1831 command to remain immediately adjacent to the object to which it is
1832 to apply after the input file has been converted to a music stream.
1833 This is often not the case, as many additional elements are inserted
1834 into the music stream implicitly. For example, when a note which is
1835 not part of a chord is processed, LilyPond implicitly inserts a
1836 @code{ChordEvent} event before the note, so separating the tweak
1837 from the note. However, if chord symbols are placed round the
1838 tweak and the note, the @code{\tweak} command comes after the
1839 @code{ChordEvent} in the music stream, so remaining adjacent to the
1840 note, and able to modify it.
1844 @lilypond[relative=2,verbatim,quote]
1845 <\tweak #'color #red c>4
1851 @lilypond[relative=2,verbatim,quote]
1852 \tweak #'color #red c4
1857 For an introduction to the syntax and uses of the tweak command
1858 see @rlearning{Tweaking methods}.
1860 When several similar items are placed at the same musical moment,
1861 the @code{\override} command cannot be used to modify just one of
1862 them -- this is where the @code{\tweak} command must be used.
1863 Items which may appear more than once at the same musical moment
1864 include the following:
1866 @c TODO expand to include any further uses of \tweak
1868 @item note heads of notes inside a chord
1869 @item articulation signs on a single note
1870 @item ties between notes in a chord
1871 @item tuplet brackets starting at the same time
1874 @c TODO add examples of these
1876 @cindex chord, modifying one note in
1878 In this example, the color of one note head and the type of another
1879 note head are modified within a single chord:
1881 @lilypond[relative=2,verbatim,quote]
1886 \tweak #'duration-log #1
1891 @code{\tweak} can be used to modify slurs:
1893 @lilypond[verbatim,quote,relative=1]
1894 c-\tweak #'thickness #5 ( d e f)
1898 For the @code{\tweak} command to work, it must
1899 remain immediately adjacent to the object to which it is
1900 to apply after the input file has been converted to a music stream.
1901 At times, LilyPond may insert additional items into the music stream
1902 during the parsing process. For example, when a note that is not
1903 explicitly part of a chord will be placed in a chord by LilyPond,
1904 so notes to be modified with @code{\tweak} must be placed inside
1907 @lilypond[relative=2,verbatim,quote]
1908 \tweak #'color #red c4
1909 <\tweak #'color #red c>4
1912 The @code{\tweak} command cannot be used to modify any item
1913 that does not appear explicitly in the input file. In particular
1914 it cannot be used to modify stems,
1915 beams or accidentals directly, since these are generated later by
1916 note heads, rather than by music elements in the input stream.
1917 Nor can @code{\tweak} be used to modify clefs or time
1918 signatures, since these become separated from any preceding
1919 @code{\tweak} command in the input stream by the automatic
1920 insertion of extra elements required to specify the context.
1922 Several @code{\tweak} commands may be placed before a
1923 notational element -- all affect it:
1925 @lilypond[verbatim,quote,relative=1]
1927 -\tweak #'style #'dashed-line
1928 -\tweak #'dash-fraction #0.2
1929 -\tweak #'thickness #3
1930 -\tweak #'color #red
1935 The music stream which is generated from a section of an input file,
1936 including any automatically inserted elements, may be examined,
1937 see @rextend{Displaying music expressions}. This may be helpful in
1938 determining what may be modified by a @code{\tweak} command, or
1939 in determining how to adjust the input to make a @code{\tweak}
1945 @rlearning{Tweaking methods}.
1948 @rextend{Displaying music expressions}.
1953 @cindex tweaks in a variable
1954 The @code{\tweak} command cannot be used inside a variable.
1956 @cindex tweaks in lyrics
1957 The @code{\tweak} commands cannot be used in @code{\lyricmode}.
1959 @cindex tweaking control points
1960 @cindex control points, tweaking
1962 The @code{\tweak} command will apply to only the first of several
1963 generated ties in a chord.
1965 @node set versus override
1966 @subsection @code{\set} vs. @code{\override}
1968 TODO -- This section is probably unnecessary now.
1971 We have seen two methods of changing properties: @code{\set} and
1972 @code{\override}. There are actually two different kinds of
1975 @code{fontSize} is a special property: it is equivalent to
1976 entering @code{\override ... #'font-size} for all pertinent
1977 objects. Since this is a common change, the special
1978 property (modified with @code{\set}) was created.
1982 @node Useful concepts and properties
1983 @section Useful concepts and properties
1988 * Direction and placement::
1989 * Context layout order::
1990 * Distances and measurements::
1991 * Staff symbol properties::
1993 * Visibility of objects::
1995 * Rotating objects::
1999 @subsection Input modes
2001 The way in which the notation contained within an input file is
2002 interpreted is determined by the current input mode.
2006 This is activated with the @code{\chordmode} command, and causes
2007 input to be interpreted with the syntax of chord notation, see
2008 @ref{Chord notation}. Chords are rendered as notes on a staff.
2010 Chord mode is also activated with the @code{\chords} command.
2011 This also creates a new @code{ChordNames} context and
2012 causes the following input to be interpreted with the syntax of
2013 chord notation and rendered as chord names in the @code{ChordNames}
2014 context, see @ref{Printing chord names}.
2018 This is activated with the @code{\drummode} command, and causes
2019 input to be interpreted with the syntax of drum notation, see
2020 @ref{Basic percussion notation}.
2022 Drum mode is also activated with the @code{\drums} command.
2023 This also creates a new @code{DrumStaff} context and causes the
2024 following input to be interpreted with the syntax of drum notation
2025 and rendered as drum symbols on a drum staff, see @ref{Basic
2026 percussion notation}.
2028 @strong{Figure mode}
2030 This is activated with the @code{\figuremode} command, and causes
2031 input to be interpreted with the syntax of figured bass, see
2032 @ref{Entering figured bass}.
2034 Figure mode is also activated with the @code{\figures} command.
2035 This also creates a new @code{FiguredBass} context and causes the
2036 following input to be interpreted with the figured bass syntax
2037 and rendered as figured bass symbols in the @code{FiguredBass}
2038 context, see @ref{Introduction to figured bass}.
2040 @strong{Fret and tab modes}
2042 There are no special input modes for entering fret and tab symbols.
2044 To create tab diagrams, enter notes or chords in note mode and
2045 render them in a @code{TabStaff} context, see
2046 @ref{Default tablatures}.
2048 To create fret diagrams above a staff, you have two choices.
2049 You can either use the @code{FretBoards} context (see
2050 @ref{Automatic fret diagrams} or you can enter them as a markup
2051 above the notes using the @code{\fret-diagram} command (see
2052 @ref{Fret diagram markups}).
2054 @strong{Lyrics mode}
2056 This is activated with the @code{\lyricmode} command, and causes
2057 input to be interpreted as lyric syllables with optional durations
2058 and associated lyric modifiers, see @ref{Vocal music}.
2060 Lyric mode is also activated with the @code{\addlyrics} command.
2061 This also creates a new @code{Lyrics} context and an implicit
2062 @code{\lyricsto} command which associates the following lyrics
2063 with the preceding music.
2065 @strong{Markup mode}
2067 This is activated with the @code{\markup} command, and causes
2068 input to be interpreted with the syntax of markup, see
2069 @ref{Text markup commands}.
2071 @c silly work-around for texinfo broken-ness
2072 @c (@strong{Note...} causes a spurious cross-reference in Info)
2075 This is the default mode or it may be activated with the
2076 @code{\notemode} command. Input is interpreted as pitches,
2077 durations, markup, etc and typeset as musical notation on a staff.
2079 It is not normally necessary to specify note mode explicitly, but
2080 it may be useful to do so in certain situations, for example if you
2081 are in lyric mode, chord mode or any other mode and want to insert
2082 something that only can be done with note mode syntax.
2084 For example, to indicate dynamic markings for the verses of a
2085 choral pieces it is necessary to enter note mode to interpret
2088 @lilypond[verbatim,relative=2,quote]
2091 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2095 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2102 @node Direction and placement
2103 @subsection Direction and placement
2105 In typesetting music the direction and placement of many items is
2106 a matter of choice. For example, the stems of notes can
2107 be directed up or down; lyrics, dynamics, and other expressive
2108 marks may be placed above or below the staff; text may be aligned
2109 left, right or center; etc. Most of these choices may be left to
2110 be determined automatically by LilyPond, but in some cases it may
2111 be desirable to force a particular direction or placement.
2113 @strong{Articulation direction indicators}
2115 By default some directions are always up or always down (e.g.
2116 dynamics or fermata), while other things can alternate between
2117 up or down based on the stem direction (like slurs or accents).
2119 @c TODO Add table showing these
2121 The default action may be overridden by prefixing the articulation
2122 by a @emph{direction indicator}. Three direction indicators are
2123 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2124 and @code{-} (meaning @qq{use default direction}). The direction
2125 indicator can usually be omitted, in which case @code{-} is assumed,
2126 but a direction indicator is @strong{always} required before
2129 @item @code{\tweak} commands
2130 @item @code{\markup} commands
2131 @item @code{\tag} commands
2132 @item string markups, e.g. -"string"
2133 @item fingering instructions, e.g. @code{-1}
2134 @item articulation shortcuts, e.g. @code{-.}, @code{->}, @code{--}
2137 Direction indicators affect only the next note:
2139 @lilypond[verbatim,quote,relative=2]
2146 @strong{The direction property}
2148 The position or direction of many layout objects is controlled
2149 by the @code{direction} property.
2151 The value of the @code{direction} property may be
2152 set to @code{1}, meaning @qq{up} or @qq{above}, or to @code{-1},
2153 meaning @qq{down} or @qq{below}. The symbols @code{UP} and
2154 @code{DOWN} may be used instead of @code{1} and @code{-1}
2155 respectively. The default direction may be specified by setting
2156 @code{direction} to @code{0} or @code{CENTER}. Alternatively,
2157 in many cases predefined commands
2158 exist to specify the direction. These are all of the form
2161 @code{\xxxUp}, @code{xxxDown}, @code{xxxNeutral}
2164 where @code{xxxNeutral} means @qq{use the default direction}.
2165 See @rlearning{Within-staff objects}.
2167 In a few cases, arpeggio being the only common example, the value
2168 of the @code{direction} property specifies whether the object
2169 is to be placed to the right or left of the parent object. In
2170 this case @code{-1} or @code{LEFT} means @qq{to the left} and
2171 @code{1} or @code{RIGHT} means @qq{to the right}. @code{0}
2172 or @code{CENTER} means @qq{use the default} direction, as before.
2175 These all have side-axis set to #X
2176 AmbitusAccidental - direction has no effect
2178 StanzaNumber - not tried
2179 TrillPitchAccidental - not tried
2180 TrillPitchGroup - not tried
2183 These indications affect all notes until they are cancelled.
2185 @lilypond[verbatim,quote,relative=2]
2195 @node Context layout order
2196 @subsection Context layout order
2198 @cindex contexts, layout order
2200 Contexts are normally positioned in a system from top to bottom
2201 in the order in which they are encountered in the input file. When
2202 contexts are nested, the outer context will include inner nested
2203 contexts as specified in the input file, provided the inner contexts
2204 are included in the outer context's @qq{accepts} list. Nested
2205 contexts which are not included in the outer context's @qq{accepts}
2206 list will be repositioned below the outer context rather than nested
2209 Note that a context will be silently created implicitly if a command
2210 is encountered when there is no suitable context available to
2211 contain it. This can give rise to unexpected new staves or scores.
2213 The default order in which contexts are laid out and the
2214 @qq{accepts} list can be changed, see @ref{Aligning contexts}.
2218 @rprogram{An extra staff appears}.
2221 @node Distances and measurements
2222 @subsection Distances and measurements
2224 @cindex distances, absolute
2225 @cindex distances, scaled
2232 Distances in LilyPond are of two types: absolute and scaled.
2234 Absolute distances are used for specifying margins, indents, and
2235 other page layout details, and are by default specified in
2236 millimeters. Distances may be specified in other units by
2237 following the quantity by @code{\mm}, @code{\cm},
2238 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27
2239 of an inch). Page layout distances can also be specified in
2240 scalable units (see the following paragraph) by appending
2241 @code{\staff-space} to the quantity.
2242 Page layout is described in detail in @ref{Page formatting}.
2244 Scaled distances are always specified in units of the staff-space
2245 or, rarely, the half staff-space. The staff-space is the distance
2246 between two adjacent staff lines. The default value can be changed
2247 globally by setting the global staff size, or it can be overridden
2248 locally by changing the @code{staff-space} property of
2249 @code{StaffSymbol}. Scaled distances automatically scale with any
2250 change to the either the global staff size or the
2251 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2252 automatically only with changes to the global staff size.
2253 The global staff size thus enables the overall size of a rendered
2254 score to be easily varied. For the methods of setting the global
2255 staff size see @ref{Setting the staff size}.
2259 If just a section of a score needs to be rendered to a different
2260 scale, for example an ossia section or a footnote, the global staff
2261 size cannot simply be changed as this would affect the entire score.
2262 In such cases the change in size is made by overriding both the
2263 @code{staff-space} property of @code{StaffSymbol} and the size of
2264 the fonts. A Scheme function, @code{magstep}, is available to
2265 convert from a font size change to the equivalent change in
2266 @code{staff-space}. For an explanation and an example of its use,
2267 see @rlearning{Length and thickness of objects}.
2272 @rlearning{Length and thickness of objects}.
2275 @ref{Page formatting},
2276 @ref{Setting the staff size}.
2279 @node Staff symbol properties
2280 @subsection Staff symbol properties
2282 @cindex adjusting staff symbol
2283 @cindex drawing staff symbol
2284 @cindex staff symbol, setting of
2286 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2287 @c Need to think of uses for these properties. Eg 'line-positions
2288 @c is used in a snippet to thicken centre line.
2289 @c If retained, add @ref to here in 1.6.2 -td
2291 The vertical position of staff lines and the number of staff lines
2292 can be defined at the same time. As the following example shows,
2293 note positions are not influenced by the staff line positions.
2295 @warning{The @code{'line-positions} property overrides the
2296 @code{'line-count} property. The number of staff lines is
2297 implicitly defined by the number of elements in the list of values
2298 for @code{'line-positions}.}
2300 @lilypond[verbatim,quote,relative=1]
2302 \override StaffSymbol #'line-positions = #'(7 3 0 -4 -6 -7)
2307 The width of a staff can be modified. The units are staff
2308 spaces. The spacing of objects inside the staff is not affected by
2311 @lilypond[verbatim,quote,relative=1]
2313 \override StaffSymbol #'width = #23
2320 @subsection Spanners
2322 Many objects of musical notation extend over several notes or even
2323 several bars. Examples are slurs, beams, tuplet brackets, volta
2324 repeat brackets, crescendi, trills, and glissandi. Such objects
2325 are collectively called @qq{spanners}, and have special properties to control
2326 their appearance and behaviour. Some of these properties are common
2327 to all spanners; others are restricted to a sub-set of the spanners.
2329 All spanners support the @code{spanner-interface}. A few, essentially
2330 those that draw a straight line between the two objects, support in
2331 addition the @code{line-spanner-interface}.
2333 @unnumberedsubsubsec Using the @code{spanner-interface}
2335 This interface provides two properties that apply to several spanners.
2337 @strong{@i{The @code{minimum-length} property}}
2339 The minimum length of the spanner is specified by the
2340 @code{minimum-length} property. Increasing this usually has the
2341 necessary effect of increasing the spacing of the notes between the
2342 two end points. However, this override has no effect on
2343 many spanners, as their length is determined by other considerations.
2344 A few examples where it is effective are shown below.
2354 Works as long as callback is made:
2358 Works not at all for:
2367 @lilypond[verbatim,quote,relative=2]
2370 % increase the length of the tie
2371 -\tweak #'minimum-length #5
2375 @lilypond[verbatim,quote,relative=2]
2377 \compressFullBarRests
2379 % increase the length of the rest bar
2380 \once \override MultiMeasureRest #'minimum-length = #20
2385 @lilypond[verbatim,quote,relative=2]
2387 % increase the length of the hairpin
2388 \override Hairpin #'minimum-length = #20
2392 This override can also be used to increase the length of slurs and
2395 @lilypond[verbatim,quote,relative=2]
2398 -\tweak #'minimum-length #5
2403 -\tweak #'minimum-length #5
2407 For some layout objects, the @code{minimum-length} property becomes
2408 effective only if the @code{set-spacing-rods} procedure is called
2409 explicitly. To do this, the @code{springs-and-rods} property should
2410 be set to @code{ly:spanner::set-spacing-rods}. For example,
2411 the minimum length of a glissando has no effect unless the
2412 @code{springs-and-rods} property is set:
2414 @lilypond[verbatim,quote,relative=1]
2418 % not effective alone
2419 \once \override Glissando #'minimum-length = #20
2422 % effective only when both overrides are present
2423 \once \override Glissando #'minimum-length = #20
2424 \once \override Glissando #'springs-and-rods = #ly:spanner::set-spacing-rods
2428 The same is true of the @code{Beam} object:
2430 @lilypond[verbatim,quote,relative=1]
2431 % not effective alone
2432 \once \override Beam #'minimum-length = #20
2435 % effective only when both overrides are present
2436 \once \override Beam #'minimum-length = #20
2437 \once \override Beam #'springs-and-rods = #ly:spanner::set-spacing-rods
2441 @strong{@i{The @code{to-barline} property}}
2443 The second useful property of the @code{spanner-interface} is
2444 @code{to-barline}. By default this is true, causing hairpins and
2445 other spanners which are terminated on the first note of a measure to
2446 end instead on the immediately preceding bar line. If set to false,
2447 the spanner will extend beyond the bar line and end on the note
2450 @lilypond[verbatim,quote,relative=2]
2451 a \< a a a a \! a a a \break
2452 \override Hairpin #'to-barline = ##f
2453 a \< a a a a \! a a a
2456 This property is not effective for all spanners. For example,
2457 setting it to @code{#t} has no effect on slurs or phrasing slurs
2458 or on other spanners for which terminating on the bar line would
2461 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2463 Objects which support the @code{line-spanner-interface} include
2466 @item @code{DynamicTextSpanner}
2467 @item @code{Glissando}
2468 @item @code{TextSpanner}
2469 @item @code{TrillSpanner}
2470 @item @code{VoiceFollower}
2473 The routine responsible for drawing the stencils for these spanners is
2474 @code{ly:line-interface::print}. This routine determines the
2475 exact location of the two end points and draws a line
2476 between them, in the style requested. The locations of the two
2477 end points of the spanner are computed on-the-fly, but it is
2478 possible to override their Y-coordinates. The
2479 properties which need to be specified are nested
2480 two levels down within the property hierarchy, but the syntax of
2481 the @code{\override} command is quite simple:
2483 @lilypond[relative=2,quote,verbatim]
2485 \once \override Glissando #'(bound-details left Y) = #3
2486 \once \override Glissando #'(bound-details right Y) = #-2
2490 The units for the @code{Y} property are @code{staff-space}s,
2491 with the center line of the staff being the zero point.
2492 For the glissando, this is the value for @code{Y} at the
2493 X-coordinate corresponding to the center point of each note head,
2494 if the line is imagined to be extended to there.
2496 If @code{Y} is not set, the value is computed from the vertical
2497 position of the corresponding attachment point of the spanner.
2499 In case of a line break, the values for the end points are
2500 specified by the @code{left-broken} and @code{right-broken}
2501 sub-lists of @code{bound-details}. For example:
2503 @lilypond[relative=2,ragged-right,verbatim,quote]
2504 \override Glissando #'breakable = ##t
2505 \override Glissando #'(bound-details right-broken Y) = #-3
2506 c1 \glissando \break
2511 A number of further properties of the @code{left} and
2512 @code{right} sub-lists of the @code{bound-details} property
2513 may be modified in the same way as @code{Y}:
2517 This sets the Y-coordinate of the end point, in @code{staff-space}s
2518 offset from the staff center line. By default, it is the center of
2519 the bound object, so a glissando points to the vertical center of
2522 For horizontal spanners, such as text spanners and trill spanners,
2523 it is hardcoded to 0.
2526 This determines where the line starts and ends in the X-direction,
2527 relative to the bound object. So, a value of @code{-1} (or
2528 @code{LEFT}) makes the line start/end at the left side of the note
2529 head it is attached to.
2532 This is the absolute X-coordinate of the end point. It is usually
2533 computed on the fly, and overriding it has little useful effect.
2536 Line spanners may have symbols at the beginning or end, which is
2537 contained in this sub-property. This is for internal use; it is
2538 recommended that @code{text} be used instead.
2541 This is a markup that is evaluated to yield the stencil. It is used
2542 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
2544 @lilypond[quote,ragged-right,fragment,relative=2,verbatim]
2545 \override TextSpanner #'(bound-details left text)
2546 = \markup { \small \bold Slower }
2547 c2\startTextSpan b c a\stopTextSpan
2550 @item stencil-align-dir-y
2551 @item stencil-offset
2552 Without setting one of these, the stencil is simply put at the
2553 end-point, centered on the line, as defined by the @code{X} and
2554 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
2555 or @code{stencil-offset} will move the symbol at the edge vertically
2556 relative to the end point of the line:
2558 @lilypond[relative=1,quote,verbatim]
2559 \override TextSpanner
2560 #'(bound-details left stencil-align-dir-y) = #-2
2561 \override TextSpanner
2562 #'(bound-details right stencil-align-dir-y) = #UP
2564 \override TextSpanner
2565 #'(bound-details left text) = #"ggg"
2566 \override TextSpanner
2567 #'(bound-details right text) = #"hhh"
2568 c4^\startTextSpan c c c \stopTextSpan
2571 Note that negative values move the text @emph{up}, contrary to the
2572 effect that might be expected, as a value of @code{-1} or
2573 @code{DOWN} means align the @emph{bottom} edge of the text with
2574 the spanner line. A value of @code{1} or @code{UP} aligns
2575 the top edge of the text with the spanner line.
2578 Setting this sub-property to @code{#t} produces an arrowhead at the
2582 This sub-property controls the space between the specified
2583 end point of the line and the actual end. Without padding, a
2584 glissando would start and end in the center of each note head.
2588 The music function @code{\endSpanners} terminates the spanner
2589 which starts on the immediately following note prematurely. It
2590 is terminated after exactly one note, or at the following bar line
2591 if @code{to-barline} is true and a bar line occurs before the next
2594 @lilypond[verbatim,quote,ragged-right,relative=2,fragment]
2596 c2 \startTextSpan c2 c2
2601 When using @code{\endSpanners} it is not necessary to close
2602 \startTextSpan with \stopTextSpan, nor is it necessary to close
2603 hairpins with @code{\!}.
2607 Internals Reference:
2608 @rinternals{TextSpanner},
2609 @rinternals{Glissando},
2610 @rinternals{VoiceFollower},
2611 @rinternals{TrillSpanner},
2612 @rinternals{line-spanner-interface}.
2615 @node Visibility of objects
2616 @subsection Visibility of objects
2618 @cindex objects, visibility of
2619 @cindex grobs, visibility of
2620 @cindex visibility of objects
2622 There are four main ways in which the visibility of layout objects
2623 can be controlled: their stencil can be removed, they can be made
2624 transparent, they can be colored white, or their
2625 @code{break-visibility} property can be overridden. The first
2626 three apply to all layout objects; the last to just a few -- the
2627 @emph{breakable} objects. The Learning Manual introduces these
2628 four techniques, see @rlearning{Visibility and color of objects}.
2630 There are also a few other techniques which are specific to
2631 certain layout objects. These are covered under Special
2635 * Removing the stencil::
2636 * Making objects transparent::
2637 * Painting objects white::
2638 * Using break-visibility::
2639 * Special considerations::
2643 @node Removing the stencil
2644 @unnumberedsubsubsec Removing the stencil
2646 @cindex stencil, removing
2648 Every layout object has a stencil property. By default this is set
2649 to the specific function which draws that object. If this property
2650 is overridden to @code{#f} no function will be called and the object
2651 will not be drawn. The default action can be recovered with
2654 @lilypond[quote,verbatim,relative=1]
2656 \override Score.BarLine #'stencil = ##f
2658 \revert Score.BarLine #'stencil
2662 @node Making objects transparent
2663 @unnumberedsubsubsec Making objects transparent
2665 @cindex transparent, making objects
2667 Every layout object has a transparent property which by default is
2668 set to @code{#f}. If set to @code{#t} the object still occupies
2669 space but is made invisible.
2671 @lilypond[quote,verbatim,relative=2]
2673 \once \override NoteHead #'transparent = ##t
2677 @node Painting objects white
2678 @unnumberedsubsubsec Painting objects white
2680 @cindex objects, coloring
2681 @cindex coloring objects
2683 @cindex printing order
2684 @cindex overwriting objects
2685 @cindex objects, overwriting
2686 @cindex grobs, overwriting
2688 Every layout object has a color property which by default is set
2689 to @code{black}. If this is overridden to @code{white} the object
2690 will be indistinguishable from the white background. However,
2691 if the object crosses other objects the color of the crossing
2692 points will be determined by the order in which they are drawn,
2693 and this may leave a ghostly image of the white object, as shown
2696 @lilypond[quote,verbatim,relative=2]
2697 \override Staff.Clef #'color = #white
2701 This may be avoided by changing the order of printing the objects.
2702 All layout objects have a @code{layer} property which should be set
2703 to an integer. Objects with the lowest value of @code{layer} are
2704 drawn first, then objects with progressively higher values are drawn,
2705 so objects with higher values overwrite objects with lower values.
2706 By default most objects are assigned a @code{layer} value of
2707 @code{1}, although a few objects, including @code{StaffSymbol} and
2708 @code{BarLine}, are assigned a value of @code{0}. The order of
2709 printing objects with the same value of @code{layer} is indeterminate.
2711 In the example above the white clef, with a default @code{layer}
2712 value of @code{1}, is drawn after the staff lines (default
2713 @code{layer} value @code{0}), so overwriting them. To change this,
2714 the @code{Clef} object must be given in a lower value of
2715 @code{layer}, say @code{-1}, so that it is drawn earlier:
2717 @lilypond[quote,verbatim,relative=2]
2718 \override Staff.Clef #'color = #white
2719 \override Staff.Clef #'layer = #-1
2723 @node Using break-visibility
2724 @unnumberedsubsubsec Using break-visibility
2726 @c TODO Add making other objects breakable
2728 @cindex break-visibility
2730 Most layout objects are printed only once, but some like
2731 bar lines, clefs, time signatures and key signatures, may need
2732 to be printed twice when a line break occurs -- once at the end
2733 of the line and again at the start of the next line. Such
2734 objects are called @emph{breakable}, and have a property, the
2735 @code{break-visibility} property to control their visibility
2736 at the three positions in which they may appear -- at the
2737 start of a line, within a line if they are changed, and at the
2738 end of a line if a change takes place there.
2740 For example, the time signature
2741 by default will be printed at the start of the first line, but
2742 nowhere else unless it changes, when it will be printed at the
2743 point at which the change occurs. If this change occurs at the
2744 end of a line the new time signature will be printed at the start
2745 of the next line and a cautionary time signature will be printed
2746 at the end of the previous line as well.
2748 This behaviour is controlled by the @code{break-visibility}
2749 property, which is explained in
2750 @c Leave this ref on a newline - formats incorrectly otherwise -td
2751 @rlearning{Visibility and color of objects}. This property takes
2752 a vector of three booleans which, in order, determine whether the
2753 object is printed at the end of, within the body of, or at the
2754 beginning of a line. Or to be more precise, before a line break,
2755 where there is no line break, or after a line break.
2757 Alternatively, these eight combinations may be specified
2758 by pre-defined functions, defined in @file{scm/@/output@/-lib@/.scm},
2759 where the last three columns indicate whether the layout objects
2760 will be visible in the positions shown at the head of the columns:
2762 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {yes} {yes} {yes}
2763 @headitem Function @tab Vector @tab Before @tab At no @tab After
2764 @headitem form @tab form @tab break @tab break @tab break
2766 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
2767 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
2768 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
2769 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
2770 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
2771 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
2772 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
2773 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
2776 The default settings of @code{break-visibility} depend on the
2777 layout object. The following table shows all the layout objects
2778 of interest which are affected by @code{break-visibility} and the
2779 default setting of this property:
2781 @multitable @columnfractions .3 .3 .4
2783 @headitem Layout object @tab Usual context @tab Default setting
2785 @c omit Ambitus as it appears not to be affected by break-visibility -td
2786 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
2787 @item @code{BarLine} @tab @code{Score} @tab calculated
2788 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
2789 @c omit the following item until it can be explained -td
2790 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
2791 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2792 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
2793 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
2794 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2795 @c omit KeyCancellation until it can be explained -td
2796 @c @item @code{KeyCancellation} @tab ?? @tab @code{begin-of-line-invisible}
2797 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
2798 @c omit LeftEdge until it can be explained -td
2799 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
2800 @item @code{OctavateEight} @tab @code{Staff} @tab @code{begin-of-line-visible}
2801 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
2802 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
2806 The example below shows the use of the vector form to control the
2807 visibility of barlines:
2809 @lilypond[quote,verbatim,relative=1,ragged-right]
2812 % Remove bar line at the end of the current line
2813 \once \override Score.BarLine #'break-visibility = #'#(#f #t #t)
2819 Although all three components of the vector used to override
2820 @code{break-visibility} must be present, not all of them are
2821 effective with every layout object, and some combinations may
2822 even give errors. The following limitations apply:
2825 @item Bar lines cannot be printed at start of line.
2826 @item A bar number cannot be printed at the start of the first
2827 line unless it is set to be different from 1.
2828 @item Clef -- see below
2829 @item Double percent repeats are either all printed or all
2830 suppressed. Use begin-of line-invisible to print and
2831 all-invisible to suppress.
2832 @item Key signature -- see below
2833 @item OctavateEight -- see below
2836 @node Special considerations
2837 @unnumberedsubsubsec Special considerations
2839 @strong{@emph{Visibility following explicit changes}}
2841 @cindex key signature, visibility following explicit change
2842 @cindex explicitKeySignatureVisibility
2843 @cindex clef, visibility following explicit change
2844 @cindex explicitClefVisibility
2846 The @code{break-visibility} property controls the visibility of
2847 key signatures and changes of clef only at the start of lines,
2848 i.e. after a break. It has no effect on the visibility of the
2849 key signature or clef following an explicit key change or an
2850 explicit clef change within or at the end of a line. In the
2851 following example the key signature following the explicit change
2852 to B-flat major is still visible, even though @code{all-invisible}
2855 @lilypond[quote,verbatim,relative=1,ragged-right]
2858 % Try to remove all key signatures
2859 \override Staff.KeySignature #'break-visibility = #all-invisible
2867 The visibility of such explicit key signature and clef changes is
2868 controlled by the @code{explicitKeySignatureVisibility} and
2869 @code{explicitClefVisibility} properties. These are the equivalent
2870 of the @code{break-visibility} property and both take a vector of
2871 three booleans or the predefined functions listed above, exactly like
2872 @code{break-visibility}. Both are properties of the Staff context,
2873 not the layout objects themselves, and so they are set using the
2874 @code{\set} command. Both are set by default to @code{all-visible}.
2875 These properties control only the visibility of key signatures and
2876 clefs resulting from explicit changes and do not affect key
2877 signatures and clefs at the beginning of lines;
2878 @code{break-visibility} must still be overridden in the appropriate
2879 object to remove these.
2881 @lilypond[quote,verbatim,relative=1,ragged-right]
2884 \set Staff.explicitKeySignatureVisibility = #all-invisible
2885 \override Staff.KeySignature #'break-visibility = #all-invisible
2892 @strong{@emph{Visibility of cautionary accidentals}}
2894 To remove the cautionary accidentals printed at an explicit key
2895 change, set the Staff context property @code{printKeyCancellation}
2898 @lilypond[quote,verbatim,relative=1,ragged-right]
2901 \set Staff.explicitKeySignatureVisibility = #all-invisible
2902 \set Staff.printKeyCancellation = ##f
2903 \override Staff.KeySignature #'break-visibility = #all-invisible
2910 With these overrides only the accidentals before the notes remain
2911 to indicate the change of key.
2913 @c TODO Add visibility of cautionary accidentals before notes
2915 @strong{@emph{Automatic bars}}
2917 @cindex automaticBars
2918 @cindex bar lines, suppressing
2920 As a special case, the printing of bar lines can also be turned off
2921 by setting the @code{automaticBars} property in the Score context.
2922 If set to @code{#f}, bar lines will not be printed automatically;
2923 they must be explicitly created with a @code{\bar} command. Unlike
2924 the @code{\cadenzaOn} predefined command, measures are still counted.
2925 Bar generation will resume according to that count if this property
2926 is later set to @code{#t}. When set to @code{#f}, line breaks can
2927 occur only at explicit @code{\bar} commands.
2931 @strong{@emph{Octavated clefs}}
2933 @cindex octavated clefs, visibility of
2934 @cindex visibility of octavated clefs
2935 @cindex clefs, visibility of octavation
2937 The small octavation symbol on octavated clefs is produced by the
2938 @code{OctavateEight} layout object. Its visibility is controlled
2939 independently from that of the @code{Clef} object, so it is
2940 necessary to apply any required @code{break-visibility} overrides
2941 to both the @code{Clef} and the @code{OctavateEight} layout objects
2942 to fully suppress such clef symbols at the start of each line.
2944 For explicit clef changes, the @code{explicitClefVisibility}
2945 property controls both the clef symbol and any octavation symbol
2951 @rlearning{Visibility and color of objects}
2955 @subsection Line styles
2957 Some performance indications, e.g., @i{rallentando} and
2958 @i{accelerando} and @i{trills} are written as text and are
2959 extended over many measures with lines, sometimes dotted or wavy.
2961 These all use the same routines as the glissando for drawing the
2962 texts and the lines, and tuning their behavior is therefore also
2963 done in the same way. It is done with a spanner, and the routine
2964 responsible for drawing the spanners is
2965 @code{ly:line-interface::print}. This routine determines the
2966 exact location of the two @i{span points} and draws a line
2967 between them, in the style requested.
2969 Here is an example showing the different line styles available,
2970 and how to tune them.
2972 @lilypond[relative=2,ragged-right,verbatim,quote]
2974 \once \override Glissando #'style = #'dashed-line
2976 \override Glissando #'style = #'dotted-line
2978 \override Glissando #'style = #'zigzag
2980 \override Glissando #'style = #'trill
2984 The locations of the end-points of the spanner are computed
2985 on-the-fly for every graphic object, but it is possible to
2989 @lilypond[relative=2,ragged-right,verbatim,quote]
2991 \once \override Glissando #'(bound-details right Y) = #-2
2995 The value for @code{Y} is set to @code{-2} for the right end
2996 point. The left side may be similarly adjusted by specifying
2997 @code{left} instead of @code{right}.
2999 If @code{Y} is not set, the value is computed from the vertical
3000 position of the left and right attachment points of the spanner.
3002 Other adjustments of spanners are possible, for details, see
3005 @node Rotating objects
3006 @subsection Rotating objects
3008 Both layout objects and elements of markup text can be rotated by
3009 any angle about any point, but the method of doing so differs.
3012 * Rotating layout objects::
3016 @node Rotating layout objects
3017 @unnumberedsubsubsec Rotating layout objects
3019 @cindex rotating objects
3020 @cindex objects, rotating
3022 All layout objects which support the @code{grob-interface} can be
3023 rotated by setting their @code{rotation} property. This takes a
3024 list of three items: the angle of rotation counter-clockwise,
3025 and the x and y coordinates of the point relative to the object's
3026 reference point about which the rotation is to be performed. The
3027 angle of rotation is specified in degrees and the coordinates in
3030 The angle of rotation and the coordinates of the rotation point must
3031 be determined by trial and error.
3033 @cindex hairpins, angled
3034 @cindex angled hairpins
3036 There are only a few situations where the rotation of layout
3037 objects is useful; the following example shows one situation where
3040 @lilypond[quote,verbatim,relative=1]
3042 \override Hairpin #'rotation = #'(20 -1 0)
3046 @node Rotating markup
3047 @unnumberedsubsubsec Rotating markup
3049 All markup text can be rotated to lie at any angle by prefixing it
3050 with the @code{\rotate} command. The command takes two arguments:
3051 the angle of rotation in degrees counter-clockwise and the text to
3052 be rotated. The extents of the text are not rotated: they take
3053 their values from the extremes of the x and y coordinates of the
3054 rotated text. In the following example the
3055 @code{outside-staff-priority} property for text is set to @code{#f}
3056 to disable the automatic collision avoidance, which would push some
3057 of the text too high.
3059 @lilypond[quote,verbatim,relative=1]
3060 \override TextScript #'outside-staff-priority = ##f
3061 g4^\markup { \rotate #30 "a G" }
3062 b^\markup { \rotate #30 "a B" }
3063 des^\markup { \rotate #30 "a D-Flat" }
3064 fis^\markup { \rotate #30 "an F-Sharp" }
3067 @node Advanced tweaks
3068 @section Advanced tweaks
3070 This section discusses various approaches to fine tuning the
3071 appearance of the printed score.
3074 * Aligning objects::
3075 * Vertical grouping of grobs::
3076 * Modifying stencils::
3077 * Modifying shapes::
3083 @rlearning{Tweaking output},
3084 @rlearning{Other sources of information}.
3087 @ref{Explaining the Internals Reference},
3088 @ref{Modifying properties}.
3091 @file{scm/@/define@/-grobs@/.scm}.
3094 @rlsr{Tweaks and overrides}.
3097 @rextend{Interfaces for programmers}.
3099 Internals Reference:
3100 @rinternals{All layout objects}.
3103 @node Aligning objects
3104 @subsection Aligning objects
3106 Graphical objects which support the @code{self-alignment-interface}
3107 and/or the @code{side-position-interface} can be aligned to a previously
3108 placed object in a variety of ways. For a list of these objects, see
3109 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3111 All graphical objects have a reference point, a horizontal extent and a
3112 vertical extent. The horizontal extent is a pair of numbers
3113 giving the displacements from the reference point of the left and
3114 right edges, displacements to the left being negative. The vertical
3115 extent is a pair of numbers giving the displacement from the reference
3116 point to the bottom and top edges, displacements down being negative.
3118 An object's position on a staff is given by the values of the
3119 @code{X-offset} and @code{Y-offset} properties. The value of
3120 @code{X-offset} gives the displacement from the X coordinate of
3121 the reference point of the parent object, and the value of
3122 @code{Y-offset} gives the displacement from the center line of the
3123 staff. The values of @code{X-offset} and @code{Y-offset} may
3124 be set directly or may be set to be calculated by procedures in order
3125 to achieve alignment with the parent object.
3127 @warning{Many objects have special positioning considerations which
3128 cause any setting of @code{X-offset} or @code{Y-offset} to be
3129 ignored or modified, even though the object supports the
3130 @code{self-alignment-interface}. Overriding the @code{X-offset}
3131 or @code{Y-offset} properties to a fixed value causes the respective
3132 @code{self-alignment} property to be disregarded.}
3134 For example, an accidental can be repositioned vertically by setting
3135 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3137 Rehearsal marks may be aligned with breakable objects such as bar
3138 lines, clef symbols, time signature symbols and key signatures. There
3139 are special properties to be found in the @code{break-aligned-interface}
3140 for positioning rehearsal marks on such objects.
3143 @ref{Using the break-alignable-interface},
3144 @rextend{Callback functions}.
3147 * Setting X-offset and Y-offset directly::
3148 * Using the side-position-interface::
3149 * Using the self-alignment-interface::
3150 * Using the break-alignable-interface::
3153 @node Setting X-offset and Y-offset directly
3154 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3156 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3157 properties of many objects. The following example shows three
3158 notes with the default fingering position and the positions with @code{X-offset}
3159 and @code{Y-offset} modified.
3161 @lilypond[verbatim,quote,relative=2]
3164 -\tweak #'X-offset #0
3165 -\tweak #'Y-offset #0
3168 -\tweak #'X-offset #-1
3169 -\tweak #'Y-offset #1
3175 @node Using the side-position-interface
3176 @unnumberedsubsubsec Using the @code{side-position-interface}
3178 An object which supports the @code{side-position-interface} can be
3179 placed next to its parent object so that
3180 the specified edges of the two objects touch. The object may be
3181 placed above, below, to the right or to the left of the parent.
3182 The parent cannot be specified; it is determined by the order of
3183 elements in the input stream. Most objects have the associated
3184 note head as their parent.
3186 The values of the @code{side-axis} and @code{direction} properties
3187 determine where the object is to be placed, as follows:
3189 @c TODO add an example of each to the table
3191 @multitable @columnfractions .3 .3 .3
3192 @headitem @code{side-axis} @tab @code{direction} @tab
3193 @headitem property @tab property @tab Placement
3195 @item @code{0} @tab @code{-1} @tab left
3196 @item @code{0} @tab @code{1} @tab right
3197 @item @code{1} @tab @code{-1} @tab below
3198 @item @code{1} @tab @code{1} @tab above
3202 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3203 the procedure @code{ly:side-position-interface::x-aligned-side}.
3204 This procedure will return the correct value of @code{X-offset} to
3205 place the object to the left or right side of the parent according
3206 to value of @code{direction}.
3208 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3209 the procedure @code{ly:side-position-interface::y-aligned-side}.
3210 This procedure will return the correct value of @code{Y-offset} to
3211 place the object to the top or bottom of the parent according
3212 to value of @code{direction}.
3214 @c TODO Add examples
3216 @node Using the self-alignment-interface
3217 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3219 @emph{Self-aligning objects horizontally}
3221 The horizontal alignment of an object which supports the
3222 @code{self-alignment-interface} is controlled by the value of
3223 the @code{self-alignment-X} property, provided the object's
3224 @code{X-offset} property is set to
3225 @code{ly:self-alignment-interface::x-aligned-on-self}.
3226 @code{self-alignment-X} may be given any
3227 real value, in units of half the total X extent of the
3228 object. Negative values move the object to the right, positive
3229 to the left. A value of @code{0} centers the object on the
3230 reference point of its parent, a value of @code{-1} aligns the
3231 left edge of the object on the reference point of its parent,
3232 and a value of @code{1} aligns the right edge of the object on the
3233 reference point of its parent. The symbols @code{LEFT},
3234 @code{CENTER} and @code{RIGHT} may be used instead of the values
3235 @code{-1, 0, 1} respectively.
3237 Normally the @code{\override} command would be used to modify the
3238 value of @code{self-alignment-X}, but the @code{\tweak} command
3239 can be used to separately align several annotations on a single
3242 @lilypond[quote,verbatim,relative=1]
3244 -\tweak #'self-alignment-X #-1
3246 -\tweak #'self-alignment-X #0
3248 -\tweak #'self-alignment-X #RIGHT
3250 -\tweak #'self-alignment-X #-2.5
3251 ^"aligned further to the right"
3254 @emph{Self-aligning objects vertically}
3256 Objects may be aligned vertically in an analogous way to aligning
3257 them horizontally if the @code{Y-offset} property is set to
3258 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3259 other mechanisms are often involved in vertical alignment: the
3260 value of @code{Y-offset} is just one variable taken into account.
3261 This may make adjusting the value of some objects tricky.
3262 The units are just half the vertical extent of the object, which
3263 is usually quite small, so quite large numbers may be required.
3264 A value of @code{-1} aligns the lower edge of the object with
3265 the reference point of the parent object, a value of @code{0}
3266 aligns the center of the object with the reference point of the
3267 parent, and a value of @code{1} aligns the top edge of the object
3268 with the reference point of the parent. The symbols @code{DOWN},
3269 @code{CENTER}, @code{UP} may be substituted for @code{-1, 0, 1}
3272 @emph{Self-aligning objects in both directions}
3274 By setting both @code{X-offset} and @code{Y-offset}, an object may
3275 be aligned in both directions simultaneously.
3277 The following example shows how to adjust a fingering mark so
3278 that it nestles close to the note head.
3280 @lilypond[quote,verbatim,relative=2]
3282 -\tweak #'self-alignment-X #0.5 % move horizontally left
3283 -\tweak #'Y-offset #ly:self-alignment-interface::y-aligned-on-self
3284 -\tweak #'self-alignment-Y #-1 % move vertically up
3289 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3291 @c Cannot document as they do not seem to operate consistently on all objects -td
3292 @c TODO investigate further
3294 The @code{aligned-on-parent} procedures are used in the same way
3295 as the @code{aligned-on-self} procedures, they difference being
3296 that they permit an object to be aligned with the @emph{edges} of
3297 the parent rather than the parent's reference point. The following
3298 example shows the difference:
3302 @lilypond[verbatim,quote]
3308 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3310 @c Cannot document as they do not seem to operate consistently on all objects -td
3311 @c TODO investigate further
3315 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3317 @node Using the break-alignable-interface
3318 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3320 @cindex align to objects
3321 @cindex break-align-symbols
3323 Rehearsal marks and bar numbers may be aligned with notation
3324 objects other than bar lines. These objects include @code{ambitus},
3325 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3326 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3327 @code{time-signature}.
3329 By default, rehearsal marks and bar numbers will be horizontally
3330 centered above the object:
3332 @lilypond[verbatim,quote,relative=1]
3333 % The rehearsal mark will be centered above the Clef
3334 \override Score.RehearsalMark #'break-align-symbols = #'(clef)
3339 % The rehearsal mark will be centered above the Time Signature
3340 \override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
3346 % The rehearsal mark will be centered above the Breath Mark
3347 \override Score.RehearsalMark #'break-align-symbols = #'(breathing-sign)
3356 A list of possible target alignment objects may be specified. If
3357 some of the objects are invisible at that point due to the setting
3358 of @code{break-visibility} or the explicit visibility settings for
3359 keys and clefs, the rehearsal mark or bar number is aligned to the
3360 first object in the list which is visible. If no objects in the
3361 list are visible the object is aligned to the bar line. If the bar
3362 line is invisible the object is aligned to the place where the bar
3365 @lilypond[verbatim,quote,relative=1]
3366 % The rehearsal mark will be centered above the Key Signature
3367 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3372 % The rehearsal mark will be centered above the Clef
3373 \set Staff.explicitKeySignatureVisibility = #all-invisible
3374 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3379 % The rehearsal mark will be centered above the Bar Line
3380 \set Staff.explicitKeySignatureVisibility = #all-invisible
3381 \set Staff.explicitClefVisibility = #all-invisible
3382 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3389 The alignment of the rehearsal mark relative to the notation object
3390 can be changed, as shown in the following example. In a score with
3391 multiple staves, this setting should be done for all the staves.
3393 @lilypond[verbatim,quote,relative=1]
3394 % The RehearsalMark will be centered above the Key Signature
3395 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3401 % The RehearsalMark will be aligned with the left edge of the Key Signature
3402 \once \override Score.KeySignature #'break-align-anchor-alignment = #LEFT
3406 % The RehearsalMark will be aligned with the right edge of the Key Signature
3407 \once \override Score.KeySignature #'break-align-anchor-alignment = #RIGHT
3413 The rehearsal mark can also be offset to the right or left of the left
3414 edge by an arbitrary amount. The units are staff-spaces:
3416 @lilypond[verbatim,quote,relative=1]
3417 % The RehearsalMark will be aligned with the left edge of the Key Signature
3418 % and then shifted right by 3.5 staff-spaces
3419 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3420 \once \override Score.KeySignature #'break-align-anchor = #3.5
3424 % The RehearsalMark will be aligned with the left edge of the Key Signature
3425 % and then shifted left by 2 staff-spaces
3426 \once \override Score.KeySignature #'break-align-anchor = #-2
3433 @node Vertical grouping of grobs
3434 @subsection Vertical grouping of grobs
3436 @c TODO Expand this section
3438 The VerticalAlignment and VerticalAxisGroup grobs work together.
3439 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3440 etc. VerticalAlignment then vertically aligns the different grobs
3441 grouped together by VerticalAxisGroup. There is usually only one
3442 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3446 @node Modifying stencils
3447 @subsection Modifying stencils
3449 All layout objects have a @code{stencil} property which is part of
3450 the @code{grob-interface}. By default, this property is usually
3451 set to a function specific to the object that is tailor-made to
3452 render the symbol which represents it in the output. For example,
3453 the standard setting for the @code{stencil} property of the
3454 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3456 The standard symbol for any object can be replaced by modifying the
3457 @code{stencil} property to reference a different, specially-written,
3458 procedure. This requires a high level of knowledge of the internal
3459 workings of LilyPond, but there is an easier way which can often
3460 produce adequate results.
3462 This is to set the @code{stencil} property to the procedure which
3463 prints text -- @code{ly:text-interface::print} -- and to add a
3464 @code{text} property to the object which is set to contain the
3465 markup text which produces the required symbol. Due to the
3466 flexibility of markup, much can be achieved -- see in particular
3467 @ref{Graphic notation inside markup}.
3469 The following example demonstrates this by changing the note head
3470 symbol to a cross within a circle.
3472 @lilypond[verbatim,quote]
3474 \once \override NoteHead #'stencil = #ly:text-interface::print
3475 \once \override NoteHead #'text = \markup {
3477 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3478 \musicglyph #"noteheads.s2cross"
3486 Any of the glyphs in the feta Font can be supplied to the
3487 @code{\musicglyph} markup command -- see @ref{The Feta font}.
3489 @c TODO Add inserting eps files or ref to later
3491 @c TODO Add inserting Postscript or ref to later
3496 @ref{Graphic notation inside markup},
3497 @ref{Formatting text},
3498 @ref{Text markup commands},
3499 @ref{The Feta font}.
3502 @node Modifying shapes
3503 @subsection Modifying shapes
3506 * Modifying ties and slurs::
3509 @node Modifying ties and slurs
3510 @unnumberedsubsubsec Modifying ties and slurs
3512 @cindex slurs, modifying
3513 @cindex ties, modifying
3514 @cindex Bézier curves
3515 @cindex Bézier control points
3517 Ties, slurs and phrasing slurs are drawn as third-order Bézier
3518 curves. If the shape of the tie or slur which is calculated
3519 automatically is not optimum, the shape may be modified manually by
3520 explicitly specifying the four control points required to define
3521 a third-order Bézier curve.
3523 Third-order or cubic Bézier curves are defined by four control
3524 points. The first and fourth control points are precisely the
3525 starting and ending points of the curve. The intermediate two
3526 control points define the shape. Animations showing how the curve
3527 is drawn can be found on the web, but the following description
3528 may be helpful. The curve starts from the first control point
3529 heading directly towards the second, gradually bending over to
3530 head towards the third and continuing to bend over to head towards
3531 the fourth, arriving there travelling directly from the third
3532 control point. The curve is entirely contained in the
3533 quadrilateral defined by the four control points.
3535 Here is an example of a case where the tie is not optimum, and
3536 where @code{\tieDown} would not help.
3538 @lilypond[verbatim,quote,relative=1]
3542 { r4 <g c,> <g c,> <g c,> }
3546 One way of improving this tie is to manually modify its control
3549 The coordinates of the Bézier control points are specified in units
3550 of staff-spaces. The X@tie{}coordinate is relative to the reference
3551 point of the note to which the tie or slur is attached, and the
3552 Y@tie{}coordinate is relative to the staff center line. The
3553 coordinates are entered as a list of four pairs of decimal numbers
3554 (reals). One approach is to estimate the coordinates of the two
3555 end points, and then guess the two intermediate points. The optimum
3556 values are then found by trial and error.
3558 It is useful to remember that a symmetric curve requires symmetric
3559 control points, and that Bézier curves have the useful property that
3560 transformations of the curve such as translation, rotation and
3561 scaling can be achieved by applying the same transformation to the
3562 curve's control points.
3564 For the example above the following override gives a satisfactory
3565 tie. Note the placement -- it has to be immediately before the note
3566 to which the start of the tie (or slur) is attached.
3568 @lilypond[verbatim,quote,relative=1]
3572 #'control-points = #'((1 . -1) (3 . 0.6) (12.5 . 0.6) (14.5 . -1))
3576 { r4 <g c,> <g c,> <g c,>4 }
3582 It is not possible to modify shapes of ties or slurs by changing
3583 the @code{control-points} property if there are more than one at
3584 the same musical moment, not even by using the @code{\tweak}
3585 command. However, the @code{tie-configuration} property of
3586 @code{TieColumn} can be overridden to set start line and direction
3587 of ties as required.
3592 @node Using music functions
3593 @section Using music functions
3595 @c TODO -- add @seealso, etc. to these subsections
3597 Where tweaks need to be reused with different music expressions,
3598 it is often convenient to make the tweak part of a @emph{music
3599 function}. In this section, we discuss only @emph{substitution}
3600 functions, where the object is to substitute a variable into a
3601 piece of LilyPond input code. Other more complex functions are
3602 described in @rextend{Music functions}.
3605 * Substitution function syntax::
3606 * Substitution function examples::
3609 @node Substitution function syntax
3610 @subsection Substitution function syntax
3612 Making a function that substitutes a variable into LilyPond
3613 code is easy. The general form of these functions is
3617 #(define-music-function
3618 (parser location @var{arg1} @var{arg2} @dots{})
3619 (@var{type1?} @var{type2?} @dots{})
3621 @var{@dots{}music@dots{}}
3628 @multitable @columnfractions .33 .66
3629 @item @code{@var{argN}}
3630 @tab @var{n}th argument
3632 @item @code{@var{typeN?}}
3633 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
3634 must return @code{#t}.
3636 @item @code{@var{@dots{}music@dots{}}}
3637 @tab normal LilyPond input, using @code{$} to reference arguments
3642 The @code{parser} and @code{location} arguments are mandatory, and
3643 are used in some advanced situations as described in the
3644 @q{Extending} manual (see @rextend{Music functions}). For
3645 substitution functions, just be sure to include them.
3647 The list of type predicates is also required. Some of the most
3648 common type predicates used in music functions are:
3652 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
3662 For a list of available type predicates, see
3663 @ref{Predefined type predicates}. User-defined type predicates
3670 @ref{Predefined type predicates}.
3673 @rextend{Music functions}.
3676 @file{lily/music-scheme.cc},
3678 @file{scm/lily.scm}.
3681 @node Substitution function examples
3682 @subsection Substitution function examples
3684 This section introduces some substitution function examples.
3685 These are not intended to be exhaustive, but rather to demonstrate
3686 some of the possibilities of simple substitution functions.
3688 In the first example, a function is defined that simplifies
3689 setting the padding of a TextScript:
3691 @lilypond[quote,verbatim,ragged-right]
3693 #(define-music-function
3694 (parser location padding)
3697 \once \override TextScript #'padding = $padding
3701 c4^"piu mosso" b a b
3703 c4^"piu mosso" d e f
3705 c4^"piu mosso" fis a g
3709 In addition to numbers, we can use music expressions such
3710 as notes for arguments to music functions:
3712 @c TODO: use a better example (the music argument is redundant).
3714 @lilypond[quote,verbatim,ragged-right]
3716 #(define-music-function
3717 (parser location note)
3720 \once \override Voice.NoteHead #'stencil =
3721 #ly:text-interface::print
3722 \once \override Voice.NoteHead #'text =
3723 \markup \musicglyph #"custodes.mensural.u0"
3724 \once \override Voice.Stem #'stencil = ##f
3728 \relative c' { c4 d e f \custosNote g }
3731 Substitution functions with multiple arguments can be defined:
3733 @lilypond[quote,verbatim,ragged-right]
3735 #(define-music-function
3736 (parser location padding tempotext)
3739 \once \override Score.MetronomeMark #'padding = $padding
3740 \tempo \markup { \bold $tempotext }
3744 \tempo \markup { "Low tempo" }
3746 \tempoPadded #4.0 #"High tempo"
3753 TODO: add missing @@ref's here.