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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
136 @node Top-level contexts - staff containers
137 @unnumberedsubsubsec Top-level contexts - staff containers
139 @strong{@emph{StaffGroup}}
141 Groups staves while adding a bracket on the left side, grouping
142 the staves together. The bar lines of the contained staves are
143 connected vertically. @code{StaffGroup} only consists of a collection
144 of staves, with a bracket in front and spanning bar lines.
146 @strong{@emph{ChoirStaff}}
148 Identical to @code{StaffGroup} except that the bar lines of the
149 contained staves are not connected vertically.
151 @strong{@emph{GrandStaff}}
153 A group of staves, with a brace on the left side, grouping the
154 staves together. The bar lines of the contained staves are
155 connected vertically.
157 @strong{@emph{PianoStaff}}
159 Just like @code{GrandStaff}, but with support for instrument names
160 to the left of each system.
162 @node Intermediate-level contexts - staves
163 @unnumberedsubsubsec Intermediate-level contexts - staves
165 @strong{@emph{Staff}}
167 Handles clefs, bar lines, keys, accidentals. It can contain
168 @code{Voice} contexts.
170 @strong{@emph{RhythmicStaff}}
172 Like @code{Staff} but for printing rhythms. Pitches are ignored;
173 the notes are printed on one line.
175 @strong{@emph{TabStaff}}
177 Context for generating tablature. By default lays the music
178 expression out as a guitar tablature, printed on six lines.
180 @strong{@emph{DrumStaff}}
182 Handles typesetting for percussion. Can contain @code{DrumVoice}
184 @strong{@emph{VaticanaStaff}}
186 Same as @code{Staff}, except that it is designed for typesetting
187 a piece in gregorian style.
189 @strong{@emph{MensuralStaff}}
191 Same as @code{Staff}, except that it is designed for typesetting
192 a piece in mensural style.
194 @node Bottom-level contexts - voices
195 @unnumberedsubsubsec Bottom-level contexts - voices
197 Voice-level contexts initialise certain properties and start
198 appropriate engravers. Being bottom-level contexts, they cannot
199 contain other contexts.
201 @strong{@emph{Voice}}
203 Corresponds to a voice on a staff. This context handles the
204 conversion of dynamic signs, stems, beams, super- and sub-scripts,
205 slurs, ties, and rests. You have to instantiate this explicitly
206 if you require multiple voices on the same staff.
208 @strong{@emph{VaticanaVoice}}
210 Same as @code{Voice}, except that it is designed for typesetting
211 a piece in gregorian style.
213 @strong{@emph{MensuralVoice}}
215 Same as @code{Voice}, with modifications for typesetting a piece in
218 @strong{@emph{Lyrics}}
220 Corresponds to a voice with lyrics. Handles the printing of a
221 single line of lyrics.
223 @strong{@emph{DrumVoice}}
225 The voice context used in a percussion staff.
227 @strong{@emph{FiguredBass}}
229 The context in which @code{BassFigure} objects are created from
230 input entered in @code{\figuremode} mode.
232 @strong{@emph{TabVoice}}
234 The voice context used within a @code{TabStaff} context. Usually
235 left to be created implicitly.
237 @strong{@emph{CueVoice}}
239 A voice context used to render notes of a reduced size, intended
240 primarily for adding cue notes to a staff, see @ref{Formatting
241 cue notes}. Usually left to be created implicitly.
243 @strong{@emph{ChordNames}}
245 Typesets chord names.
250 Then the following, which I don't know what to do with:
252 * GregorianTranscriptionVoice
253 * GregorianTranscriptionStaff
256 Engraves fretboards from chords. Not easy... Not
258 There is now some documentation on FretBoards in the NR, under
259 instrument-specific notation -- cds.
264 Hard coded entry point for LilyPond. Cannot be tuned.
266 Silently discards all musical information given to this
271 @node Creating contexts
272 @subsection Creating contexts
274 @c TODO more complete descriptions rather than learning style
276 For scores with only one voice and one staff, contexts are
277 created automatically. For more complex scores, it is necessary to
278 create them by hand. There are three commands that do this.
283 The easiest command is @code{\new}, and it also the quickest to type.
284 It is prepended to a music expression, for example
288 @cindex Context, creating
291 \new @var{type} @var{music expression}
295 where @var{type} is a context name (like @code{Staff} or
296 @code{Voice}). This command creates a new context, and starts
297 interpreting the @var{music expression} with that.
299 A practical application of @code{\new} is a score with many
300 staves. Each part that should be on its own staff, is preceded with
303 @lilypond[quote,verbatim,relative=2,ragged-right]
310 The @code{\new} command may also give a name to the context,
313 \new @var{type} = @var{id} @var{music}
315 However, this user specified name is only used if there is no other
316 context already earlier with the same name.
322 Like @code{\new}, the @code{\context} command also directs a music
323 expression to a context object, but gives the context an explicit name. The
327 \context @var{type} = @var{id} @var{music}
330 This form will search for an existing context of type @var{type}
331 called @var{id}. If that context does not exist yet, a new
332 context with the specified name is created. This is useful if
333 the context is referred to later on. For example, when
334 setting lyrics the melody is in a named context
337 \context Voice = "@b{tenor}" @var{music}
341 so the texts can be properly aligned to its notes,
344 \new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
349 Another possible use of named contexts is funneling two different
350 music expressions into one context. In the following example,
351 articulations and notes are entered separately,
355 arts = @{ s4-. s4-> @}
358 They are combined by sending both to the same @code{Voice} context,
362 \new Staff \context Voice = "A" \music
363 \context Voice = "A" \arts
366 @lilypond[quote,ragged-right]
370 \new Staff \context Voice = "A" \music
371 \context Voice = "A" \arts
375 With this mechanism, it is possible to define an Urtext (original
376 edition), with the option to put several distinct articulations on the
379 @cindex creating contexts
382 The third command for creating contexts is
384 \context @var{type} @var{music}
389 This is similar to @code{\context} with @code{= @var{id}}, but matches
390 any context of type @var{type}, regardless of its given name.
392 This variant is used with music expressions that can be interpreted at
393 several levels. For example, the @code{\applyOutput} command (see
394 @rextend{Running a function on all layout objects}). Without an explicit
395 @code{\context}, it is usually applied to @code{Voice}
398 \applyOutput #'@var{context} #@var{function} % apply to Voice
401 To have it interpreted at the @code{Score} or @code{Staff} level use
405 \applyOutput #'Score #@var{function}
406 \applyOutput #'Staff #@var{function}
411 @node Keeping contexts alive
412 @subsection Keeping contexts alive
414 @cindex contexts, keeping alive
415 @cindex contexts, lifetime
417 Contexts are usually terminated at the first musical moment in
418 which they have nothing to do. So @code{Voice} contexts die as
419 soon as they contain no events; @code{Staff} contexts die as soon
420 as all the @code{Voice} contexts within them contain no events; etc.
421 This can cause difficulties if earlier contexts which have died
422 have to be referenced, for example, when changing staves with
423 @code{\change} commands, associating lyrics with a voice with
424 @code{\lyricsto} commands, or when adding further musical events to
427 There is an exception to this general rule: just one of the
428 @code{Voice} contexts in a @code{Staff} context or in a
429 @code{<<...>>} construct will always persist to the end of the
430 enclosing @code{Staff} context or @code{<<...>>} construct, even
431 though there may be periods when it has nothing to do. The context
432 to persist in this way will be the first one encountered in the
433 first enclosed @code{@{...@}} construct, ignoring any in enclosed
434 @code{<<...>>} constructs.
436 Any context can be kept alive by ensuring it has something to do at
437 every musical moment. @code{Staff} contexts are kept alive by
438 ensuring one of their voices is kept alive. One way of doing this
439 is to add spacer rests to a voice in parallel with the real music.
440 These need to be added to every @code{Voice} context which needs to
441 be kept alive. If several voices are to be used sporadically it is
442 safest to keep them all alive rather than attempting to rely on the
443 exceptions mentioned above.
445 In the following example, both voice A and voice B are kept alive
446 in this way for the duration of the piece:
448 @lilypond[quote,verbatim]
449 musicA = \relative c'' { d4 d d d }
450 musicB = \relative c'' { g4 g g g }
453 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
454 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
459 \context Voice = "A" {
463 \context Voice = "B" {
467 \context Voice = "A" { \musicA }
468 \context Voice = "B" { \musicB }
469 \context Voice = "A" { \musicA }
480 @cindex lyrics, aligning with sporadic melody
482 The following example shows how a sporadic melody line with lyrics
483 might be written using this approach. In a real situation the
484 melody and accompaniment would consist of several different
487 @lilypond[quote,verbatim]
488 melody = \relative c'' { a4 a a a }
489 accompaniment = \relative c' { d4 d d d }
490 words = \lyricmode { These words fol -- low the mel -- o -- dy }
493 \new Staff = "music" {
495 \new Voice = "melody" {
497 s1*4 % Keep Voice "melody" alive for 4 bars
500 \new Voice = "accompaniment" {
505 \context Voice = "melody" { \melody }
506 \context Voice = "accompaniment" { \accompaniment }
508 \context Voice = "accompaniment" { \accompaniment }
510 \context Voice = "melody" { \melody }
511 \context Voice = "accompaniment" { \accompaniment }
516 \new Lyrics \with { alignAboveContext = #"music" }
517 \lyricsto "melody" { \words }
522 An alternative way, which may be better in many circumstances, is
523 to keep the melody line alive by simply including spacer notes to
524 line it up correctly with the accompaniment:
526 @lilypond[quote,verbatim]
527 melody = \relative c'' {
533 accompaniment = \relative c' {
539 words = \lyricmode { These words fol -- low the mel -- o -- dy }
543 \new Staff = "music" {
545 \new Voice = "melody" {
549 \new Voice = "accompaniment" {
555 \new Lyrics \with { alignAboveContext = #"music" }
556 \lyricsto "melody" { \words }
562 @node Modifying context plug-ins
563 @subsection Modifying context plug-ins
565 @c TODO Should this be Modifying engravers or Modifying contexts?
567 Notation contexts (like @code{Score} and @code{Staff}) not only
569 they also contain plug-ins called @q{engravers} that create notation
570 elements. For example, the @code{Voice} context contains a
571 @code{Note_head_engraver} and the @code{Staff} context contains a
572 @code{Key_signature_engraver}.
574 For a full a description of each plug-in, see
576 @rinternals{Engravers and Performers}.
579 Internals Reference @expansion{} Translation @expansion{} Engravers.
581 Every context described in
583 @rinternals{Contexts}
586 Internals Reference @expansion{} Translation @expansion{} Context.
588 lists the engravers used for that context.
591 It can be useful to shuffle around these plug-ins. This is done by
592 starting a new context with @code{\new} or @code{\context}, and
598 \new @var{context} \with @{
611 where the @dots{} should be the name of an engraver. Here is a simple
612 example which removes @code{Time_signature_engraver} and
613 @code{Clef_engraver} from a @code{Staff} context,
615 @lilypond[quote,relative=1,verbatim]
621 \remove "Time_signature_engraver"
622 \remove "Clef_engraver"
629 In the second staff there are no time signature or clef symbols. This
630 is a rather crude method of making objects disappear since it will affect
631 the entire staff. This method also influences the spacing, which may or
632 may not be desirable. More sophisticated methods of blanking objects
633 are shown in @rlearning{Visibility and color of objects}.
635 The next example shows a practical application. Bar lines and time
636 signatures are normally synchronized across the score. This is done
637 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
638 This plug-in keeps an administration of time signature, location
639 within the measure, etc. By moving these engraver from @code{Score} to
640 @code{Staff} context, we can have a score where each staff has its own
643 @cindex polymetric scores
644 @cindex Time signatures, multiple
646 @lilypond[quote,verbatim]
650 \consists "Timing_translator"
651 \consists "Default_bar_line_engraver"
657 \consists "Timing_translator"
658 \consists "Default_bar_line_engraver"
667 \remove "Timing_translator"
668 \remove "Default_bar_line_engraver"
676 Usually the order in which the engravers are specified
677 does not matter, but in a few special cases the order
678 is important, for example where one engraver writes
679 a property and another reads it, or where one engraver
680 creates a grob and another must process it. The order in
681 which the engravers are specified is the order in which
682 they are called to carry out their processing.
684 The following orderings are important: the
685 @code{Bar_engraver} must normally be first, and
686 the @code{New_fingering_engraver} must come before
687 the @code{Script_column_engraver}. There may be others
688 with ordering dependencies.
690 @node Changing context default settings
691 @subsection Changing context default settings
693 The context settings which are to be used by default in
694 @code{Score}, @code{Staff} and @code{Voice} contexts may be specified
695 in a @code{\layout} block, as illustrated in the following example.
696 The @code{\layout} block should be placed within the @code{\score}
697 block to which it is to apply, but outside any music.
699 Note that the @code{\set} command itself and the context must be
700 omitted when the context default values are specified in this way:
702 @lilypond[quote,verbatim]
705 a4^"Really small, thicker stems, no time signature" a a a
712 \override Stem #'thickness = #4.0
713 \remove "Time_signature_engraver"
719 In this example, the @code{\Staff} command specifies that the
720 subsequent specifications are to be applied to all staves within
723 Modifications can be made to the @code{Score} context or all
724 @code{Voice} contexts in a similar way.
728 It is not possible to collect context changes in a variable and apply
729 them to a @code{\context} definition by referring to that variable.
731 The @code{\Staff \RemoveEmptyStaves} will overwrite your current
732 @code{\Staff} settings. If you wish to change the defaults for a
733 staff which uses @code{\Staff \RemoveEmptyStaves}, you must do so
734 after calling @code{\Staff \RemoveEmptyStaves}, ie
739 \Staff \RemoveEmptyStaves
741 \override Stem #'thickness = #4.0
746 @c TODO: add \with in here.
750 @node Defining new contexts
751 @subsection Defining new contexts
753 @cindex contexts, defining new
754 @cindex engravers, including in contexts
769 Specific contexts, like @code{Staff} and @code{Voice}, are made of
770 simple building blocks. It is possible to create new types of
771 contexts with different combinations of engraver plug-ins.
773 The next example shows how to build a different type of
774 @code{Voice} context from scratch. It will be similar to
775 @code{Voice}, but only prints centered slash note heads. It can be used
776 to indicate improvisation in jazz pieces,
778 @lilypond[quote,ragged-right]
781 \type "Engraver_group"
782 \consists "Note_heads_engraver"
783 \consists "Rhythmic_column_engraver"
784 \consists "Text_engraver"
785 \consists Pitch_squash_engraver
786 squashedPosition = #0
787 \override NoteHead #'style = #'slash
788 \override Stem #'transparent = ##t
792 \accepts "ImproVoice"
796 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
797 c4 c^"undress" c_"while playing :)" c }
803 These settings are defined within a @code{\context} block inside a
804 @code{\layout} block,
814 In the following discussion, the example input shown should go in place
815 of the @dots{} in the previous fragment.
817 First it is necessary to define a name for the new context:
823 Since it is similar to the @code{Voice}, we want commands that work
824 on (existing) @code{Voice}s to remain working. This is achieved by
825 giving the new context an alias @code{Voice},
831 The context will print notes and instructive texts, so we need to add
832 the engravers which provide this functionality,
835 \consists Note_heads_engraver
836 \consists Text_engraver
839 but we only need this on the center line,
842 \consists Pitch_squash_engraver
843 squashedPosition = #0
846 The @rinternals{Pitch_squash_engraver} modifies note heads (created
847 by @rinternals{Note_heads_engraver}) and sets their vertical
848 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
851 The notes look like a slash, and have no stem,
854 \override NoteHead #'style = #'slash
855 \override Stem #'transparent = ##t
858 All these plug-ins have to cooperate, and this is achieved with a
859 special plug-in, which must be marked with the keyword @code{\type}.
860 This should always be @code{Engraver_group}.
863 \type "Engraver_group"
871 \type "Engraver_group"
872 \consists "Note_heads_engraver"
873 \consists "Text_engraver"
874 \consists Pitch_squash_engraver
875 squashedPosition = #0
876 \override NoteHead #'style = #'slash
877 \override Stem #'transparent = ##t
883 Contexts form hierarchies. We want to hang the @code{ImproVoice}
884 under @code{Staff}, just like normal @code{Voice}s. Therefore, we
885 modify the @code{Staff} definition with the @code{\accepts}
896 The opposite of @code{\accepts} is @code{\denies},
897 which is sometimes needed when reusing existing context definitions.
899 Putting both into a @code{\layout} block, like
909 \accepts "ImproVoice"
914 Then the output at the start of this subsection can be entered as
922 c c_"while playing :)"
929 @node Aligning contexts
930 @subsection Aligning contexts
932 New contexts may be aligned above or below existing contexts. This
933 could be useful in setting up a vocal staff (@rlearning{Vocal ensembles}) and
936 @c TODO Better example needed. Ref LM, and expand on it.
939 @funindex alignAboveContext
940 @funindex alignBelowContext
942 @lilypond[quote,ragged-right]
945 \relative c' \new Staff = "main" {
948 \new Staff \with { alignAboveContext = #"main" } \ossia
955 @cindex nested contexts
956 @cindex contexts, nested
961 Contexts like @code{PianoStaff} can contain other contexts
962 nested within them. Contexts which are acceptable for nesting
963 are defined by the @qq{accepts} list of a context. Contexts
964 which are not in this list are placed below the outer context
965 in the printed score.
966 For example, the @code{PianoStaff} context is defined by default
967 to accept @code{Staff} and @code{FiguredBass} contexts within
968 it, but not (for example) a @code{Lyrics} context. So in the
969 following structure the lyrics are placed below the piano staff
970 rather than between the two staves:
972 @lilypond[verbatim,quote,relative=1]
975 \new Staff { e4 d c2 }
976 \addlyrics { Three blind mice }
984 The @qq{accepts} list of a context can be modified to include
985 additional nested contexts, so if we wanted the lyrics to appear
986 between the two staves we could use:
988 @lilypond[verbatim,quote,relative=1]
989 \new PianoStaff \with { \accepts Lyrics }
991 \new Staff { e4 d c2 }
992 \addlyrics { Three blind mice }
1000 The opposite of @code{\accepts} is @code{\denies}; this removes a
1001 context from the @qq{accepts} list.
1003 @node Explaining the Internals Reference
1004 @section Explaining the Internals Reference
1008 * Navigating the program reference::
1009 * Layout interfaces::
1010 * Determining the grob property::
1011 * Naming conventions::
1014 @node Navigating the program reference
1015 @subsection Navigating the program reference
1017 @c TODO remove this (it's in the LM)
1018 @c Replace with more factual directions
1020 Suppose we want to move the fingering indication in the fragment
1023 @lilypond[quote,relative=2,verbatim]
1029 If you visit the documentation on fingering instructions (in
1030 @ref{Fingering instructions}), you will notice:
1035 Internals Reference: @rinternals{Fingering}.
1040 @c outdated info; probably will delete.
1042 This fragment points to two parts of the program reference: a page
1043 on @code{FingeringEvent} and one on @code{Fingering}.
1045 The page on @code{FingeringEvent} describes the properties of the music
1046 expression for the input @code{-2}. The page contains many links
1047 forward. For example, it says
1050 Accepted by: @rinternals{Fingering_engraver},
1054 That link brings us to the documentation for the Engraver, the
1058 This engraver creates the following layout objects: @rinternals{Fingering}.
1061 In other words, once the @code{FingeringEvent}s are interpreted, the
1062 @code{Fingering_engraver} plug-in will process them.
1066 @c I can't figure out what this is supposed to mean. -gp
1068 The @code{Fingering_engraver} is also listed to create
1069 @rinternals{Fingering} objects,
1071 @c old info? it doesn't make any sense to me with our current docs.
1073 second bit of information listed under @b{See also} in the Notation
1078 The programmer's reference is available as an HTML document. It is
1079 highly recommended that you read it in HTML form, either online or
1080 by downloading the HTML documentation. This section will be much more
1081 difficult to understand if you are using the
1085 Follow the link to @rinternals{Fingering}. At the top of the
1089 Fingering objects are created by: @rinternals{Fingering_engraver} and
1090 @rinternals{New_fingering_engraver}.
1093 By following related links inside the program reference, we can follow the
1094 flow of information within the program:
1098 @item @rinternals{Fingering}:
1099 @rinternals{Fingering} objects are created by:
1100 @rinternals{Fingering_engraver}
1102 @item @rinternals{Fingering_engraver}:
1103 Music types accepted: @rinternals{fingering-event}
1105 @item @rinternals{fingering-event}:
1106 Music event type @code{fingering-event} is in Music expressions named
1107 @rinternals{FingeringEvent}
1110 This path goes against the flow of information in the program: it
1111 starts from the output, and ends at the input event. You could
1112 also start at an input event, and read with the flow of
1113 information, eventually ending up at the output object(s).
1115 The program reference can also be browsed like a normal document. It
1116 contains chapters on
1118 @rinternals{Music definitions},
1121 @code{Music definitions}
1123 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1124 chapter lists all the definitions used and all properties that may be
1128 @node Layout interfaces
1129 @subsection Layout interfaces
1131 @cindex interface, layout
1132 @cindex layout interface
1135 The HTML page that we found in the previous section describes the
1136 layout object called @rinternals{Fingering}. Such an object is a
1137 symbol within the score. It has properties that store numbers (like
1138 thicknesses and directions), but also pointers to related objects. A
1139 layout object is also called a @emph{Grob}, which is short for Graphical
1140 Object. For more details about Grobs, see @rinternals{grob-interface}.
1142 The page for @code{Fingering} lists the definitions for the
1143 @code{Fingering} object. For example, the page says
1146 @code{padding} (dimension, in staff space):
1152 which means that the number will be kept at a distance of at least 0.5
1156 Each layout object may have several functions as a notational or
1157 typographical element. For example, the Fingering object
1158 has the following aspects
1162 Its size is independent of the horizontal spacing, unlike slurs or beams.
1165 It is a piece of text. Granted, it is usually a very short text.
1168 That piece of text is typeset with a font, unlike slurs or beams.
1171 Horizontally, the center of the symbol should be aligned to the
1172 center of the note head.
1175 Vertically, the symbol is placed next to the note and the staff.
1178 The vertical position is also coordinated with other superscript
1179 and subscript symbols.
1182 Each of these aspects is captured in so-called @emph{interface}s,
1183 which are listed on the @rinternals{Fingering} page at the bottom
1186 This object supports the following interfaces:
1187 @rinternals{item-interface},
1188 @rinternals{self-alignment-interface},
1189 @rinternals{side-position-interface}, @rinternals{text-interface},
1190 @rinternals{text-script-interface}, @rinternals{font-interface},
1191 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1194 Clicking any of the links will take you to the page of the respective
1195 object interface. Each interface has a number of properties. Some of
1196 them are not user-serviceable (@q{Internal properties}), but others
1199 We have been talking of @emph{the} @code{Fingering} object, but actually it
1200 does not amount to much. The initialization file (see
1201 @rlearning{Other sources of information})
1202 @file{scm/@/define@/-grobs@/.scm} shows the soul of the @q{object},
1207 (avoid-slur . around)
1208 (slur-padding . 0.2)
1209 (staff-padding . 0.5)
1210 (self-alignment-X . 0)
1211 (self-alignment-Y . 0)
1212 (script-priority . 100)
1213 (stencil . ,ly:text-interface::print)
1214 (direction . ,ly:script-interface::calc-direction)
1215 (font-encoding . fetaText)
1216 (font-size . -5) ; don't overlap when next to heads.
1217 (meta . ((class . Item)
1218 (interfaces . (finger-interface
1220 text-script-interface
1222 side-position-interface
1223 self-alignment-interface
1224 item-interface))))))
1228 As you can see, the @code{Fingering} object is nothing more than a
1229 bunch of variable settings, and the webpage in the Internals Reference
1230 is directly generated from this definition.
1233 @node Determining the grob property
1234 @subsection Determining the grob property
1236 @c TODO remove this (it's in the LM)
1237 @c Replace with more factual directions
1239 Recall that we wanted to change the position of the @b{2} in
1241 @lilypond[quote,relative=2,verbatim]
1247 Since the @b{2} is vertically positioned next to its note, we have to
1248 meddle with the interface associated with this positioning. This is
1249 done using @code{side-position-interface}. The page for this interface
1253 @code{side-position-interface}
1255 Position a victim object (this one) next to other objects (the
1256 support). The property @code{direction} signifies where to put the
1257 victim object relative to the support (left or right, up or down?)
1262 Below this description, the variable @code{padding} is described as
1267 (dimension, in staff space)
1269 Add this much extra space between objects that are next to each other.
1273 By increasing the value of @code{padding}, we can move the
1274 fingering away from the note head. The following command inserts
1275 3 staff spaces of white
1276 between the note and the fingering:
1278 \once \override Voice.Fingering #'padding = #3
1281 Inserting this command before the Fingering object is created,
1282 i.e., before @code{c2}, yields the following result:
1284 @lilypond[quote,relative=2,verbatim]
1285 \once \override Voice.Fingering #'padding = #3
1292 In this case, the context for this tweak is @code{Voice}. This
1293 fact can also be deduced from the program reference, for the page for
1294 the @rinternals{Fingering_engraver} plug-in says
1297 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1301 @node Naming conventions
1302 @subsection Naming conventions
1304 Another thing that is needed, is an overview of the various naming
1308 @item scheme functions: lowercase-with-hyphens (incl. one-word
1310 @item scheme functions: ly:plus-scheme-style
1311 @item music events, music classes and music properties:
1313 @item Grob interfaces: scheme-style
1314 @item backend properties: scheme-style (but X and Y!)
1315 @item contexts (and MusicExpressions and grobs): Capitalized or
1317 @item context properties: lowercaseFollowedByCamelCase
1319 Capitalized_followed_by_lowercase_and_with_underscores
1322 Questions to be answered:
1324 @item Which of these are conventions and which are rules?
1325 @item Which are rules of the underlying language, and which are
1329 @node Modifying properties
1330 @section Modifying properties
1332 @c TODO change the menu and subsection node names to use
1333 @c backslash once the new macro to handle the refs
1334 @c is available. Need to find and change all refs at
1335 @c the same time. -td
1338 * Overview of modifying properties::
1340 * The override command::
1341 * The tweak command::
1342 * set versus override::
1343 * Modifying alists::
1347 @node Overview of modifying properties
1348 @subsection Overview of modifying properties
1350 Each context is responsible for creating certain types of graphical
1351 objects. The settings used for printing these objects are also stored by
1352 context. By changing these settings, the appearance of objects can be
1355 There are two different kinds of properties stored in contexts:
1356 context properties and grob properties. Context properties are
1357 properties that apply to the context as a whole and control
1358 how the context itself is displayed. In contrast, grob properties
1359 apply to specific grob types that will be displayed in the context.
1361 The @code{\set} and @code{\unset} commands are used to change values
1362 for context properties. The @code{\override} and @code{\revert}
1363 commands are used to change values for grob properties.
1366 The syntax for this is
1369 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1372 Here @var{name} is the name of a graphical object, like
1373 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1374 variable of the formatting system (@q{grob property} or @q{layout
1375 property}). The latter is a symbol, so it must be quoted. The
1376 subsection @ref{Modifying properties}, explains what to fill in
1377 for @var{name}, @var{property}, and @var{value}. Here we only
1378 discuss the functionality of this command.
1383 \override Staff.Stem #'thickness = #4.0
1387 makes stems thicker (the default is 1.3, with staff line thickness as a
1388 unit). Since the command specifies @code{Staff} as context, it only
1389 applies to the current staff. Other staves will keep their normal
1390 appearance. Here we see the command in action:
1392 @lilypond[quote,verbatim,relative=2]
1394 \override Staff.Stem #'thickness = #4.0
1400 The @code{\override} command changes the definition of the @code{Stem}
1401 within the current @code{Staff}. After the command is interpreted
1402 all stems are thickened.
1404 Analogous to @code{\set}, the @var{context} argument may be left out,
1405 causing the default context @code{Voice} to be used. Adding
1406 @code{\once} applies the change during one timestep only.
1408 @lilypond[quote,verbatim,relative=2]
1410 \once \override Stem #'thickness = #4.0
1415 The @code{\override} must be done before the object is
1416 started. Therefore, when altering @emph{Spanner} objects such as slurs
1417 or beams, the @code{\override} command must be executed at the moment
1418 when the object is created. In this example,
1420 @lilypond[quote,verbatim,relative=2]
1421 \override Slur #'thickness = #3.0
1423 \override Beam #'beam-thickness = #0.6
1428 the slur is fatter but the beam is not. This is because the command for
1429 @code{Beam} comes after the Beam is started, so it has no effect.
1431 Analogous to @code{\unset}, the @code{\revert} command for a context
1432 undoes an @code{\override} command; like with @code{\unset}, it only
1433 affects settings that were made in the same context. In other words, the
1434 @code{\revert} in the next example does not do anything.
1437 \override Voice.Stem #'thickness = #4.0
1438 \revert Staff.Stem #'thickness
1441 Some tweakable options are called @q{subproperties} and reside inside
1442 properties. To tweak those, use commands of the form
1444 @c leave this as a long long
1446 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1453 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1460 @rinternals{Backend},
1461 @rinternals{All layout objects},
1462 @rinternals{OverrideProperty},
1463 @rinternals{RevertProperty},
1464 @rinternals{PropertySet}.
1469 The back-end is not very strict in type-checking object properties.
1470 Cyclic references in Scheme values for properties can cause hangs
1471 or crashes, or both.
1475 @node The set command
1476 @subsection The @code{@bs{}set} command
1480 @cindex changing properties
1482 Each context has a set of @emph{properties}, variables contained
1483 in that context. Context properties are changed with the @code{\set}
1484 command, which has the following syntax:
1487 \set @var{context}.@var{property} = #@var{value}
1490 @var{value} is a Scheme object, which is why it must be preceded by
1491 the @code{#} character.
1493 Contexts properties are usually named in
1494 @code{studlyCaps}. They mostly control the translation from
1495 music to notation, e.g. @code{localKeySignature} (for determining
1496 whether to print accidentals), or @code{measurePosition} (for
1497 determining when to print a bar line). Context properties can
1498 change value over time while interpreting a piece of music;
1499 @code{measurePosition} is an obvious example of
1500 this. Context properties are modified with @code{\set}.
1502 For example, multimeasure rests will be combined into a single bar
1503 if the context property @code{skipBars} is set to @code{#t}:
1505 @lilypond[quote,verbatim,relative=2]
1507 \set Score.skipBars = ##t
1511 If the @var{context} argument is left out, then the property will be
1512 set in the current bottom context (typically @code{ChordNames},
1513 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1515 @lilypond[quote,verbatim,relative=2]
1516 \set Score.autoBeaming = ##f
1520 \set autoBeaming = ##t
1528 The change is applied @q{on-the-fly}, during the music, so that the
1529 setting only affects the second group of eighth notes.
1531 Note that the bottom-most context does not always contain the property
1532 that you wish to change -- for example, attempting to set the
1533 @code{skipBars} property of the default bottom context, in this case
1534 @code{Voice}, will have no effect, because skipBars is a property of
1535 the @code{Score} context.
1537 @lilypond[quote,verbatim,relative=2]
1543 Contexts are hierarchical, so if an enclosing context was specified, for
1544 example @code{Staff}, then the change would also apply to all
1545 @code{Voice}s in the current staff.
1549 The @code{\unset} command:
1552 \unset @var{context}.@var{property}
1556 is used to remove the definition of @var{property} from
1557 @var{context}. This command removes
1558 the definition only if it is set in @var{context}.
1559 Properties that have been set in enclosing contexts will
1560 not be altered by an unset in an enclosed context:
1562 @lilypond[quote,verbatim,relative=2]
1563 \set Score.autoBeaming = ##t
1568 \unset Score.autoBeaming
1576 Like @code{\set}, the @var{context} argument does not have to be
1577 specified for a bottom context, so the two statements
1580 \set Voice.autoBeaming = ##t
1581 \set autoBeaming = ##t
1585 are equivalent if the current bottom context is @code{Voice}.
1589 Preceding a @code{\set} command by @code{\once} makes the
1590 setting apply to only a single time-step:
1592 @lilypond[quote,verbatim,relative=2]
1594 \once \set fontSize = #4.7
1599 A full description of all available context properties is in the
1600 internals reference, see
1602 @rinternals{Tunable context properties}.
1605 Translation @expansion{} Tunable context properties.
1610 Internals Reference:
1612 @rinternals{Tunable context properties}.
1615 @cindex grob properties
1616 @cindex properties, grob
1620 @node The override command
1621 @subsection The @code{\override} command
1623 There is a special type of context property: the grob
1624 description. Grob descriptions are named in @code{StudlyCaps}
1625 (starting with capital letters). They contain the
1626 @q{default settings} for a particular kind of grob as an
1627 association list. See @file{scm/@/define@/-grobs@/.scm}
1628 to see the settings for each grob description. Grob descriptions
1629 are modified with @code{\override}.
1631 @code{\override} is actually a shorthand;
1634 \override @var{context}.@var{GrobName} #'@var{property} = #@var{value}
1638 is more or less equivalent to
1640 @c leave this long line -gp
1642 \set @var{context}.@var{GrobName} =
1643 #(cons (cons '@var{property} @var{value})
1644 <previous value of @var{context}.@var{GrobName}>)
1647 The value of @code{context}.@code{GrobName} (the alist) is used to initialize
1648 the properties of individual grobs. Grobs have
1649 properties, named in Scheme style, with
1650 @code{dashed-words}. The values of grob properties change
1651 during the formatting process: formatting basically amounts
1652 to computing properties using callback functions.
1654 For example, we can increase the thickness of a note stem by
1655 overriding the @code{thickness} property of the @code{Stem}
1658 @lilypond[quote,verbatim,relative=2]
1660 \override Voice.Stem #'thickness = #3.0
1664 If no context is specified in an @code{\override}, the bottom
1667 @lilypond[quote,verbatim,relative=2]
1668 { \override Staff.Stem #'thickness = #3.0
1672 \override Stem #'thickness = #0.5
1682 @cindex reverting overrides
1683 @cindex overrides, reverting
1685 The effects of @code{\override} can be undone by @code{\revert}:
1687 @lilypond[quote,verbatim,relative=2]
1689 \override Voice.Stem #'thickness = #3.0
1691 \revert Voice.Stem #'thickness
1695 The effects of @code{\override} and @code{\revert} apply to all
1696 grobs in the affected context from the current time forward:
1698 @lilypond[quote,verbatim,relative=2]
1703 \override Staff.Stem #'thickness = #3.0
1707 \revert Staff.Stem #'thickness
1715 @cindex overriding for only one moment
1717 @code{\once} can be used with @code{\override}
1718 to affect only the current time step:
1720 @lilypond[quote,verbatim,relative=2]
1724 \override Stem #'thickness = #3.0
1728 \once \override Stem #'thickness = #3.0
1737 Commands which change output generally look like
1740 \override Voice.Stem #'thickness = #3.0
1744 To construct this tweak we must determine these bits of information:
1747 @item the context: here @code{Voice}.
1748 @item the layout object: here @code{Stem}.
1749 @item the layout property: here @code{thickness}.
1750 @item a sensible value: here @code{3.0}.
1753 Some tweakable options are called @q{subproperties} and reside inside
1754 properties. To tweak those, use commands in the form
1757 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1760 @cindex internal documentation
1761 @cindex finding graphical objects
1762 @cindex graphical object descriptions
1765 @cindex internal documentation
1767 For many properties, regardless of the data type of the property, setting the
1768 property to false ( @code{##f} ) will result in turning it off, causing
1769 LilyPond to ignore that property entirely. This is particularly useful for
1770 turning off grob properties which may otherwise be causing problems.
1772 We demonstrate how to glean this information from the notation manual
1773 and the program reference.
1778 Internals Reference:
1779 @rinternals{Backend}
1781 @node The tweak command
1782 @subsection The @code{\tweak} command
1787 Changing grob properties
1788 with @code{\override} causes the changes to apply to all of the
1789 given grobs in the context at the moment the change applies.
1790 Sometimes, however, it is desirable to have changes apply to just
1791 one grob, rather than to all grobs in the affected context. This is
1792 accomplished with the @code{\tweak} command, which has the following
1796 \tweak #'@code{grob-property} #@code{value}
1799 The @code{\tweak} command applies to the object that immediately
1800 follows @code{value} in the music stream.
1803 In some cases, it is possible to take a short-cut for tuning
1804 graphical objects. For objects that are created directly from
1805 an item in the input file, you can use the @code{\tweak} command.
1808 @lilypond[relative=2,verbatim,quote]
1813 \tweak #'duration-log #1
1816 -\tweak #'padding #8
1822 But the main use of the @code{\tweak} command is to modify just
1823 one of a number of notation elements which start at the same musical
1824 moment, like the notes of a chord, or tuplet brackets which start
1827 The @code{\tweak} command sets a property in the following object
1828 directly, without requiring the grob name or context to be
1829 specified. For this to work, it is necessary for the @code{\tweak}
1830 command to remain immediately adjacent to the object to which it is
1831 to apply after the input file has been converted to a music stream.
1832 This is often not the case, as many additional elements are inserted
1833 into the music stream implicitly. For example, when a note which is
1834 not part of a chord is processed, LilyPond implicitly inserts a
1835 @code{ChordEvent} event before the note, so separating the tweak
1836 from the note. However, if chord symbols are placed round the
1837 tweak and the note, the @code{\tweak} command comes after the
1838 @code{ChordEvent} in the music stream, so remaining adjacent to the
1839 note, and able to modify it.
1843 @lilypond[relative=2,verbatim,quote]
1844 <\tweak #'color #red c>4
1850 @lilypond[relative=2,verbatim,quote]
1851 \tweak #'color #red c4
1856 For an introduction to the syntax and uses of the tweak command
1857 see @rlearning{Tweaking methods}.
1859 When several similar items are placed at the same musical moment,
1860 the @code{\override} command cannot be used to modify just one of
1861 them -- this is where the @code{\tweak} command must be used.
1862 Items which may appear more than once at the same musical moment
1863 include the following:
1865 @c TODO expand to include any further uses of \tweak
1867 @item note heads of notes inside a chord
1868 @item articulation signs on a single note
1869 @item ties between notes in a chord
1870 @item tuplet brackets starting at the same time
1873 @c TODO add examples of these
1875 @cindex chord, modifying one note in
1877 In this example, the color of one note head and the type of another
1878 note head are modified within a single chord:
1880 @lilypond[relative=2,verbatim,quote]
1885 \tweak #'duration-log #1
1890 @code{\tweak} can be used to modify slurs:
1892 @lilypond[verbatim,quote,relative=1]
1893 c-\tweak #'thickness #5 ( d e f)
1897 For the @code{\tweak} command to work, it must
1898 remain immediately adjacent to the object to which it is
1899 to apply after the input file has been converted to a music stream.
1900 At times, LilyPond may insert additional items into the music stream
1901 during the parsing process. For example, when a note that is not
1902 explicitly part of a chord will be placed in a chord by LilyPond,
1903 so notes to be modified with @code{\tweak} must be placed inside
1906 @lilypond[relative=2,verbatim,quote]
1907 \tweak #'color #red c4
1908 <\tweak #'color #red c>4
1911 The @code{\tweak} command cannot be used to modify any item
1912 that does not appear explicitly in the input file. In particular
1913 it cannot be used to modify stems,
1914 beams or accidentals directly, since these are generated later by
1915 note heads, rather than by music elements in the input stream.
1916 Nor can @code{\tweak} be used to modify clefs or time
1917 signatures, since these become separated from any preceding
1918 @code{\tweak} command in the input stream by the automatic
1919 insertion of extra elements required to specify the context.
1921 Several @code{\tweak} commands may be placed before a
1922 notational element -- all affect it:
1924 @lilypond[verbatim,quote,relative=1]
1926 -\tweak #'style #'dashed-line
1927 -\tweak #'dash-fraction #0.2
1928 -\tweak #'thickness #3
1929 -\tweak #'color #red
1934 The music stream which is generated from a section of an input file,
1935 including any automatically inserted elements, may be examined,
1936 see @rextend{Displaying music expressions}. This may be helpful in
1937 determining what may be modified by a @code{\tweak} command, or
1938 in determining how to adjust the input to make a @code{\tweak}
1944 @rlearning{Tweaking methods}.
1947 @rextend{Displaying music expressions}.
1952 @cindex tweaks in a variable
1953 The @code{\tweak} command cannot be used inside a variable.
1955 @cindex tweaks in lyrics
1956 The @code{\tweak} commands cannot be used in @code{\lyricmode}.
1958 @cindex tweaking control points
1959 @cindex control points, tweaking
1961 The @code{\tweak} command will apply to only the first of several
1962 generated ties in a chord.
1964 @node set versus override
1965 @subsection @code{\set} vs. @code{\override}
1967 TODO -- This section is probably unnecessary now.
1970 We have seen two methods of changing properties: @code{\set} and
1971 @code{\override}. There are actually two different kinds of
1974 @code{fontSize} is a special property: it is equivalent to
1975 entering @code{\override ... #'font-size} for all pertinent
1976 objects. Since this is a common change, the special
1977 property (modified with @code{\set}) was created.
1982 @node Modifying alists
1983 @subsection Modifying alists
1985 Some user-configurable properties are internally represented as
1986 @emph{alists} (association lists), which store pairs of
1987 @emph{keys} and @emph{values}. The structure of an alist is:
1990 #((@var{key1} . @var{value1})
1991 (@var{key2} . @var{value2})
1992 (@var{key3} . @var{value3})
1996 If an alist is a grob property or @code{\paper} variable, its keys
1997 can be modified individually without affecting other keys.
1999 For example, to reduce the space between adjacent staves in a
2000 system, use the @code{between-staff-spacing} property of the
2001 @code{StaffGrouper} grob. The property is an alist with four
2002 keys: @code{padding}, @code{space}, @code{minimum-distance}, and
2003 @code{stretchability}. Three of the four keys have initialized
2004 default values, which are defined (along with all the other grob
2005 properties) in the file @file{scm/define-grobs.scm}:
2008 (between-staff-spacing . ((padding . 1)
2010 (minimum-distance . 7)))
2013 One way to bring the staves closer together is by reducing the
2014 value of the @code{space} key (@code{9}) to match the value of
2015 @code{minimum-distance} (@code{7}). To modify a single key
2016 individually, use a nested declaration:
2018 @lilypond[quote,verbatim]
2019 % default space between staves
2021 \new Staff { \clef treble c''1 }
2022 \new Staff { \clef bass c1 }
2025 % reduced space between staves
2026 \new PianoStaff \with {
2027 \override StaffGrouper #'between-staff-spacing #'space = #7
2029 \new Staff { \clef treble c''1 }
2030 \new Staff { \clef bass c1 }
2034 Using a nested declaration will update the specified key
2035 (@code{space} in the above example) without altering any other
2036 keys already set for the same property.
2038 Now suppose we want the staves to be as close as possible without
2039 overlapping. The simplest way to do this is to set all four alist
2040 keys to zero. In that case, it is not necessary to set each key
2041 individually with nested declarations. Instead, the property can
2042 be completely re-defined with one declaration, as an alist:
2044 @lilypond[quote,verbatim]
2045 \new PianoStaff \with {
2046 \override StaffGrouper #'between-staff-spacing =
2049 (minimum-distance . 0)
2050 (stretchability . 0))
2052 \new Staff { \clef treble c''1 }
2053 \new Staff { \clef bass c1 }
2057 Note that any keys not explicitly listed in the alist definition
2058 will be reset to their @emph{default-when-unset} values. In the
2059 case of @code{between-staff-spacing}, any unset key-values would
2060 be reset to zero (except @code{stretchability}, which takes the
2061 value of @code{space} when unset). Thus the following two
2062 declarations are equivalent:
2065 \override StaffGrouper #'between-staff-spacing =
2068 \override StaffGrouper #'between-staff-spacing =
2071 (minimum-distance . 0)
2072 (stretchability . 7))
2075 One (possibly unintended) consequence of this is the removal of
2076 any @emph{initialized} default values that are set in an
2077 initialization file and loaded each time an input file is
2078 compiled. In the above example, the initialized default values
2079 for @code{padding} and @code{minimum-distance} (defined in
2080 @file{scm/define-grobs.scm}) are reset to their default-when-unset
2081 values (zero for both keys). Defining a property or variable as
2082 an alist (of any size) will always reset all unset key-values to
2083 their default-when-unset values. Unless this is the intended
2084 result, it is safer to update key-values individually with a
2087 @warning{Nested declarations will not work for context property
2088 alists (such as @code{beamExceptions}, @code{keySignature},
2089 @code{timeSignatureSettings}, etc.). These properties can only be
2090 modified by completely re-defining them as alists.}
2093 @node Useful concepts and properties
2094 @section Useful concepts and properties
2099 * Direction and placement::
2100 * Context layout order::
2101 * Distances and measurements::
2102 * Staff symbol properties::
2104 * Visibility of objects::
2106 * Rotating objects::
2110 @subsection Input modes
2112 The way in which the notation contained within an input file is
2113 interpreted is determined by the current input mode.
2117 This is activated with the @code{\chordmode} command, and causes
2118 input to be interpreted with the syntax of chord notation, see
2119 @ref{Chord notation}. Chords are rendered as notes on a staff.
2121 Chord mode is also activated with the @code{\chords} command.
2122 This also creates a new @code{ChordNames} context and
2123 causes the following input to be interpreted with the syntax of
2124 chord notation and rendered as chord names in the @code{ChordNames}
2125 context, see @ref{Printing chord names}.
2129 This is activated with the @code{\drummode} command, and causes
2130 input to be interpreted with the syntax of drum notation, see
2131 @ref{Basic percussion notation}.
2133 Drum mode is also activated with the @code{\drums} command.
2134 This also creates a new @code{DrumStaff} context and causes the
2135 following input to be interpreted with the syntax of drum notation
2136 and rendered as drum symbols on a drum staff, see @ref{Basic
2137 percussion notation}.
2139 @strong{Figure mode}
2141 This is activated with the @code{\figuremode} command, and causes
2142 input to be interpreted with the syntax of figured bass, see
2143 @ref{Entering figured bass}.
2145 Figure mode is also activated with the @code{\figures} command.
2146 This also creates a new @code{FiguredBass} context and causes the
2147 following input to be interpreted with the figured bass syntax
2148 and rendered as figured bass symbols in the @code{FiguredBass}
2149 context, see @ref{Introduction to figured bass}.
2151 @strong{Fret and tab modes}
2153 There are no special input modes for entering fret and tab symbols.
2155 To create tab diagrams, enter notes or chords in note mode and
2156 render them in a @code{TabStaff} context, see
2157 @ref{Default tablatures}.
2159 To create fret diagrams above a staff, you have two choices.
2160 You can either use the @code{FretBoards} context (see
2161 @ref{Automatic fret diagrams} or you can enter them as a markup
2162 above the notes using the @code{\fret-diagram} command (see
2163 @ref{Fret diagram markups}).
2165 @strong{Lyrics mode}
2167 This is activated with the @code{\lyricmode} command, and causes
2168 input to be interpreted as lyric syllables with optional durations
2169 and associated lyric modifiers, see @ref{Vocal music}.
2171 Lyric mode is also activated with the @code{\addlyrics} command.
2172 This also creates a new @code{Lyrics} context and an implicit
2173 @code{\lyricsto} command which associates the following lyrics
2174 with the preceding music.
2176 @strong{Markup mode}
2178 This is activated with the @code{\markup} command, and causes
2179 input to be interpreted with the syntax of markup, see
2180 @ref{Text markup commands}.
2182 @c silly work-around for texinfo broken-ness
2183 @c (@strong{Note...} causes a spurious cross-reference in Info)
2186 This is the default mode or it may be activated with the
2187 @code{\notemode} command. Input is interpreted as pitches,
2188 durations, markup, etc and typeset as musical notation on a staff.
2190 It is not normally necessary to specify note mode explicitly, but
2191 it may be useful to do so in certain situations, for example if you
2192 are in lyric mode, chord mode or any other mode and want to insert
2193 something that only can be done with note mode syntax.
2195 For example, to indicate dynamic markings for the verses of a
2196 choral pieces it is necessary to enter note mode to interpret
2199 @lilypond[verbatim,relative=2,quote]
2202 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2206 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2213 @node Direction and placement
2214 @subsection Direction and placement
2216 In typesetting music the direction and placement of many items is
2217 a matter of choice. For example, the stems of notes can
2218 be directed up or down; lyrics, dynamics, and other expressive
2219 marks may be placed above or below the staff; text may be aligned
2220 left, right or center; etc. Most of these choices may be left to
2221 be determined automatically by LilyPond, but in some cases it may
2222 be desirable to force a particular direction or placement.
2224 @strong{Articulation direction indicators}
2226 By default some directions are always up or always down (e.g.
2227 dynamics or fermata), while other things can alternate between
2228 up or down based on the stem direction (like slurs or accents).
2230 @c TODO Add table showing these
2232 The default action may be overridden by prefixing the articulation
2233 by a @emph{direction indicator}. Three direction indicators are
2234 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2235 and @code{-} (meaning @qq{use default direction}). The direction
2236 indicator can usually be omitted, in which case @code{-} is assumed,
2237 but a direction indicator is @strong{always} required before
2240 @item @code{\tweak} commands
2241 @item @code{\markup} commands
2242 @item @code{\tag} commands
2243 @item string markups, e.g. -"string"
2244 @item fingering instructions, e.g. @code{-1}
2245 @item articulation shortcuts, e.g. @code{-.}, @code{->}, @code{--}
2248 Direction indicators affect only the next note:
2250 @lilypond[verbatim,quote,relative=2]
2257 @strong{The direction property}
2259 The position or direction of many layout objects is controlled
2260 by the @code{direction} property.
2262 The value of the @code{direction} property may be
2263 set to @code{1}, meaning @qq{up} or @qq{above}, or to @code{-1},
2264 meaning @qq{down} or @qq{below}. The symbols @code{UP} and
2265 @code{DOWN} may be used instead of @code{1} and @code{-1}
2266 respectively. The default direction may be specified by setting
2267 @code{direction} to @code{0} or @code{CENTER}. Alternatively,
2268 in many cases predefined commands
2269 exist to specify the direction. These are all of the form
2272 @code{\xxxUp}, @code{xxxDown}, @code{xxxNeutral}
2275 where @code{xxxNeutral} means @qq{use the default direction}.
2276 See @rlearning{Within-staff objects}.
2278 In a few cases, arpeggio being the only common example, the value
2279 of the @code{direction} property specifies whether the object
2280 is to be placed to the right or left of the parent object. In
2281 this case @code{-1} or @code{LEFT} means @qq{to the left} and
2282 @code{1} or @code{RIGHT} means @qq{to the right}. @code{0}
2283 or @code{CENTER} means @qq{use the default} direction, as before.
2286 These all have side-axis set to #X
2287 AmbitusAccidental - direction has no effect
2289 StanzaNumber - not tried
2290 TrillPitchAccidental - not tried
2291 TrillPitchGroup - not tried
2294 These indications affect all notes until they are cancelled.
2296 @lilypond[verbatim,quote,relative=2]
2306 @node Context layout order
2307 @subsection Context layout order
2309 @cindex contexts, layout order
2311 Contexts are normally positioned in a system from top to bottom
2312 in the order in which they are encountered in the input file. When
2313 contexts are nested, the outer context will include inner nested
2314 contexts as specified in the input file, provided the inner contexts
2315 are included in the outer context's @qq{accepts} list. Nested
2316 contexts which are not included in the outer context's @qq{accepts}
2317 list will be repositioned below the outer context rather than nested
2320 Note that a context will be silently created implicitly if a command
2321 is encountered when there is no suitable context available to
2322 contain it. This can give rise to unexpected new staves or scores.
2324 The default order in which contexts are laid out and the
2325 @qq{accepts} list can be changed, see @ref{Aligning contexts}.
2329 @rprogram{An extra staff appears}.
2332 @node Distances and measurements
2333 @subsection Distances and measurements
2335 @cindex distances, absolute
2336 @cindex distances, scaled
2343 Distances in LilyPond are of two types: absolute and scaled.
2345 Absolute distances are used for specifying margins, indents, and
2346 other page layout details, and are by default specified in
2347 millimeters. Distances may be specified in other units by
2348 following the quantity by @code{\mm}, @code{\cm},
2349 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27
2350 of an inch). Page layout distances can also be specified in
2351 scalable units (see the following paragraph) by appending
2352 @code{\staff-space} to the quantity.
2353 Page layout is described in detail in @ref{Page formatting}.
2355 Scaled distances are always specified in units of the staff-space
2356 or, rarely, the half staff-space. The staff-space is the distance
2357 between two adjacent staff lines. The default value can be changed
2358 globally by setting the global staff size, or it can be overridden
2359 locally by changing the @code{staff-space} property of
2360 @code{StaffSymbol}. Scaled distances automatically scale with any
2361 change to the either the global staff size or the
2362 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2363 automatically only with changes to the global staff size.
2364 The global staff size thus enables the overall size of a rendered
2365 score to be easily varied. For the methods of setting the global
2366 staff size see @ref{Setting the staff size}.
2370 If just a section of a score needs to be rendered to a different
2371 scale, for example an ossia section or a footnote, the global staff
2372 size cannot simply be changed as this would affect the entire score.
2373 In such cases the change in size is made by overriding both the
2374 @code{staff-space} property of @code{StaffSymbol} and the size of
2375 the fonts. A Scheme function, @code{magstep}, is available to
2376 convert from a font size change to the equivalent change in
2377 @code{staff-space}. For an explanation and an example of its use,
2378 see @rlearning{Length and thickness of objects}.
2383 @rlearning{Length and thickness of objects}.
2386 @ref{Page formatting},
2387 @ref{Setting the staff size}.
2390 @node Staff symbol properties
2391 @subsection Staff symbol properties
2393 @cindex adjusting staff symbol
2394 @cindex drawing staff symbol
2395 @cindex staff symbol, setting of
2397 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2398 @c Need to think of uses for these properties. Eg 'line-positions
2399 @c is used in a snippet to thicken centre line.
2400 @c If retained, add @ref to here in 1.6.2 -td
2402 The vertical position of staff lines and the number of staff lines
2403 can be defined at the same time. As the following example shows,
2404 note positions are not influenced by the staff line positions.
2406 @warning{The @code{'line-positions} property overrides the
2407 @code{'line-count} property. The number of staff lines is
2408 implicitly defined by the number of elements in the list of values
2409 for @code{'line-positions}.}
2411 @lilypond[verbatim,quote,relative=1]
2413 \override StaffSymbol #'line-positions = #'(7 3 0 -4 -6 -7)
2418 The width of a staff can be modified. The units are staff
2419 spaces. The spacing of objects inside the staff is not affected by
2422 @lilypond[verbatim,quote,relative=1]
2424 \override StaffSymbol #'width = #23
2431 @subsection Spanners
2433 Many objects of musical notation extend over several notes or even
2434 several bars. Examples are slurs, beams, tuplet brackets, volta
2435 repeat brackets, crescendi, trills, and glissandi. Such objects
2436 are collectively called @qq{spanners}, and have special properties to control
2437 their appearance and behaviour. Some of these properties are common
2438 to all spanners; others are restricted to a sub-set of the spanners.
2440 All spanners support the @code{spanner-interface}. A few, essentially
2441 those that draw a straight line between the two objects, support in
2442 addition the @code{line-spanner-interface}.
2444 @unnumberedsubsubsec Using the @code{spanner-interface}
2446 This interface provides two properties that apply to several spanners.
2448 @strong{@i{The @code{minimum-length} property}}
2450 The minimum length of the spanner is specified by the
2451 @code{minimum-length} property. Increasing this usually has the
2452 necessary effect of increasing the spacing of the notes between the
2453 two end points. However, this override has no effect on
2454 many spanners, as their length is determined by other considerations.
2455 A few examples where it is effective are shown below.
2465 Works as long as callback is made:
2469 Works not at all for:
2478 @lilypond[verbatim,quote,relative=2]
2481 % increase the length of the tie
2482 -\tweak #'minimum-length #5
2486 @lilypond[verbatim,quote,relative=2]
2488 \compressFullBarRests
2490 % increase the length of the rest bar
2491 \once \override MultiMeasureRest #'minimum-length = #20
2496 @lilypond[verbatim,quote,relative=2]
2498 % increase the length of the hairpin
2499 \override Hairpin #'minimum-length = #20
2503 This override can also be used to increase the length of slurs and
2506 @lilypond[verbatim,quote,relative=2]
2509 -\tweak #'minimum-length #5
2514 -\tweak #'minimum-length #5
2518 For some layout objects, the @code{minimum-length} property becomes
2519 effective only if the @code{set-spacing-rods} procedure is called
2520 explicitly. To do this, the @code{springs-and-rods} property should
2521 be set to @code{ly:spanner::set-spacing-rods}. For example,
2522 the minimum length of a glissando has no effect unless the
2523 @code{springs-and-rods} property is set:
2525 @lilypond[verbatim,quote,relative=1]
2529 % not effective alone
2530 \once \override Glissando #'minimum-length = #20
2533 % effective only when both overrides are present
2534 \once \override Glissando #'minimum-length = #20
2535 \once \override Glissando #'springs-and-rods = #ly:spanner::set-spacing-rods
2539 The same is true of the @code{Beam} object:
2541 @lilypond[verbatim,quote,relative=1]
2542 % not effective alone
2543 \once \override Beam #'minimum-length = #20
2546 % effective only when both overrides are present
2547 \once \override Beam #'minimum-length = #20
2548 \once \override Beam #'springs-and-rods = #ly:spanner::set-spacing-rods
2552 @strong{@i{The @code{to-barline} property}}
2554 The second useful property of the @code{spanner-interface} is
2555 @code{to-barline}. By default this is true, causing hairpins and
2556 other spanners which are terminated on the first note of a measure to
2557 end instead on the immediately preceding bar line. If set to false,
2558 the spanner will extend beyond the bar line and end on the note
2561 @lilypond[verbatim,quote,relative=2]
2562 a \< a a a a \! a a a \break
2563 \override Hairpin #'to-barline = ##f
2564 a \< a a a a \! a a a
2567 This property is not effective for all spanners. For example,
2568 setting it to @code{#t} has no effect on slurs or phrasing slurs
2569 or on other spanners for which terminating on the bar line would
2572 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2574 Objects which support the @code{line-spanner-interface} include
2577 @item @code{DynamicTextSpanner}
2578 @item @code{Glissando}
2579 @item @code{TextSpanner}
2580 @item @code{TrillSpanner}
2581 @item @code{VoiceFollower}
2584 The routine responsible for drawing the stencils for these spanners is
2585 @code{ly:line-interface::print}. This routine determines the
2586 exact location of the two end points and draws a line
2587 between them, in the style requested. The locations of the two
2588 end points of the spanner are computed on-the-fly, but it is
2589 possible to override their Y-coordinates. The
2590 properties which need to be specified are nested
2591 two levels down within the property hierarchy, but the syntax of
2592 the @code{\override} command is quite simple:
2594 @lilypond[relative=2,quote,verbatim]
2596 \once \override Glissando #'(bound-details left Y) = #3
2597 \once \override Glissando #'(bound-details right Y) = #-2
2601 The units for the @code{Y} property are @code{staff-space}s,
2602 with the center line of the staff being the zero point.
2603 For the glissando, this is the value for @code{Y} at the
2604 X-coordinate corresponding to the center point of each note head,
2605 if the line is imagined to be extended to there.
2607 If @code{Y} is not set, the value is computed from the vertical
2608 position of the corresponding attachment point of the spanner.
2610 In case of a line break, the values for the end points are
2611 specified by the @code{left-broken} and @code{right-broken}
2612 sub-lists of @code{bound-details}. For example:
2614 @lilypond[relative=2,ragged-right,verbatim,quote]
2615 \override Glissando #'breakable = ##t
2616 \override Glissando #'(bound-details right-broken Y) = #-3
2617 c1 \glissando \break
2622 A number of further properties of the @code{left} and
2623 @code{right} sub-lists of the @code{bound-details} property
2624 may be modified in the same way as @code{Y}:
2628 This sets the Y-coordinate of the end point, in @code{staff-space}s
2629 offset from the staff center line. By default, it is the center of
2630 the bound object, so a glissando points to the vertical center of
2633 For horizontal spanners, such as text spanners and trill spanners,
2634 it is hardcoded to 0.
2637 This determines where the line starts and ends in the X-direction,
2638 relative to the bound object. So, a value of @code{-1} (or
2639 @code{LEFT}) makes the line start/end at the left side of the note
2640 head it is attached to.
2643 This is the absolute X-coordinate of the end point. It is usually
2644 computed on the fly, and overriding it has little useful effect.
2647 Line spanners may have symbols at the beginning or end, which is
2648 contained in this sub-property. This is for internal use; it is
2649 recommended that @code{text} be used instead.
2652 This is a markup that is evaluated to yield the stencil. It is used
2653 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
2655 @lilypond[quote,ragged-right,relative=2,verbatim]
2656 \override TextSpanner #'(bound-details left text)
2657 = \markup { \small \bold Slower }
2658 c2\startTextSpan b c a\stopTextSpan
2661 @item stencil-align-dir-y
2662 @item stencil-offset
2663 Without setting one of these, the stencil is simply put at the
2664 end-point, centered on the line, as defined by the @code{X} and
2665 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
2666 or @code{stencil-offset} will move the symbol at the edge vertically
2667 relative to the end point of the line:
2669 @lilypond[relative=1,quote,verbatim]
2670 \override TextSpanner
2671 #'(bound-details left stencil-align-dir-y) = #-2
2672 \override TextSpanner
2673 #'(bound-details right stencil-align-dir-y) = #UP
2675 \override TextSpanner
2676 #'(bound-details left text) = #"ggg"
2677 \override TextSpanner
2678 #'(bound-details right text) = #"hhh"
2679 c4^\startTextSpan c c c \stopTextSpan
2682 Note that negative values move the text @emph{up}, contrary to the
2683 effect that might be expected, as a value of @code{-1} or
2684 @code{DOWN} means align the @emph{bottom} edge of the text with
2685 the spanner line. A value of @code{1} or @code{UP} aligns
2686 the top edge of the text with the spanner line.
2689 Setting this sub-property to @code{#t} produces an arrowhead at the
2693 This sub-property controls the space between the specified
2694 end point of the line and the actual end. Without padding, a
2695 glissando would start and end in the center of each note head.
2699 The music function @code{\endSpanners} terminates the spanner
2700 which starts on the immediately following note prematurely. It
2701 is terminated after exactly one note, or at the following bar line
2702 if @code{to-barline} is true and a bar line occurs before the next
2705 @lilypond[verbatim,quote,ragged-right,relative=2]
2707 c2 \startTextSpan c2 c2
2712 When using @code{\endSpanners} it is not necessary to close
2713 \startTextSpan with \stopTextSpan, nor is it necessary to close
2714 hairpins with @code{\!}.
2718 Internals Reference:
2719 @rinternals{TextSpanner},
2720 @rinternals{Glissando},
2721 @rinternals{VoiceFollower},
2722 @rinternals{TrillSpanner},
2723 @rinternals{line-spanner-interface}.
2726 @node Visibility of objects
2727 @subsection Visibility of objects
2729 @cindex objects, visibility of
2730 @cindex grobs, visibility of
2731 @cindex visibility of objects
2733 There are four main ways in which the visibility of layout objects
2734 can be controlled: their stencil can be removed, they can be made
2735 transparent, they can be colored white, or their
2736 @code{break-visibility} property can be overridden. The first
2737 three apply to all layout objects; the last to just a few -- the
2738 @emph{breakable} objects. The Learning Manual introduces these
2739 four techniques, see @rlearning{Visibility and color of objects}.
2741 There are also a few other techniques which are specific to
2742 certain layout objects. These are covered under Special
2746 * Removing the stencil::
2747 * Making objects transparent::
2748 * Painting objects white::
2749 * Using break-visibility::
2750 * Special considerations::
2754 @node Removing the stencil
2755 @unnumberedsubsubsec Removing the stencil
2757 @cindex stencil, removing
2759 Every layout object has a stencil property. By default this is set
2760 to the specific function which draws that object. If this property
2761 is overridden to @code{#f} no function will be called and the object
2762 will not be drawn. The default action can be recovered with
2765 @lilypond[quote,verbatim,relative=1]
2767 \override Score.BarLine #'stencil = ##f
2769 \revert Score.BarLine #'stencil
2773 @node Making objects transparent
2774 @unnumberedsubsubsec Making objects transparent
2776 @cindex transparent, making objects
2778 Every layout object has a transparent property which by default is
2779 set to @code{#f}. If set to @code{#t} the object still occupies
2780 space but is made invisible.
2782 @lilypond[quote,verbatim,relative=2]
2784 \once \override NoteHead #'transparent = ##t
2788 @node Painting objects white
2789 @unnumberedsubsubsec Painting objects white
2791 @cindex objects, coloring
2792 @cindex coloring objects
2794 @cindex printing order
2795 @cindex overwriting objects
2796 @cindex objects, overwriting
2797 @cindex grobs, overwriting
2799 Every layout object has a color property which by default is set
2800 to @code{black}. If this is overridden to @code{white} the object
2801 will be indistinguishable from the white background. However,
2802 if the object crosses other objects the color of the crossing
2803 points will be determined by the order in which they are drawn,
2804 and this may leave a ghostly image of the white object, as shown
2807 @lilypond[quote,verbatim,relative=2]
2808 \override Staff.Clef #'color = #white
2812 This may be avoided by changing the order of printing the objects.
2813 All layout objects have a @code{layer} property which should be set
2814 to an integer. Objects with the lowest value of @code{layer} are
2815 drawn first, then objects with progressively higher values are drawn,
2816 so objects with higher values overwrite objects with lower values.
2817 By default most objects are assigned a @code{layer} value of
2818 @code{1}, although a few objects, including @code{StaffSymbol} and
2819 @code{BarLine}, are assigned a value of @code{0}. The order of
2820 printing objects with the same value of @code{layer} is indeterminate.
2822 In the example above the white clef, with a default @code{layer}
2823 value of @code{1}, is drawn after the staff lines (default
2824 @code{layer} value @code{0}), so overwriting them. To change this,
2825 the @code{Clef} object must be given in a lower value of
2826 @code{layer}, say @code{-1}, so that it is drawn earlier:
2828 @lilypond[quote,verbatim,relative=2]
2829 \override Staff.Clef #'color = #white
2830 \override Staff.Clef #'layer = #-1
2834 @node Using break-visibility
2835 @unnumberedsubsubsec Using break-visibility
2837 @c TODO Add making other objects breakable
2839 @cindex break-visibility
2841 Most layout objects are printed only once, but some like
2842 bar lines, clefs, time signatures and key signatures, may need
2843 to be printed twice when a line break occurs -- once at the end
2844 of the line and again at the start of the next line. Such
2845 objects are called @emph{breakable}, and have a property, the
2846 @code{break-visibility} property to control their visibility
2847 at the three positions in which they may appear -- at the
2848 start of a line, within a line if they are changed, and at the
2849 end of a line if a change takes place there.
2851 For example, the time signature
2852 by default will be printed at the start of the first line, but
2853 nowhere else unless it changes, when it will be printed at the
2854 point at which the change occurs. If this change occurs at the
2855 end of a line the new time signature will be printed at the start
2856 of the next line and a cautionary time signature will be printed
2857 at the end of the previous line as well.
2859 This behaviour is controlled by the @code{break-visibility}
2860 property, which is explained in
2861 @c Leave this ref on a newline - formats incorrectly otherwise -td
2862 @rlearning{Visibility and color of objects}. This property takes
2863 a vector of three booleans which, in order, determine whether the
2864 object is printed at the end of, within the body of, or at the
2865 beginning of a line. Or to be more precise, before a line break,
2866 where there is no line break, or after a line break.
2868 Alternatively, these eight combinations may be specified
2869 by pre-defined functions, defined in @file{scm/@/output@/-lib@/.scm},
2870 where the last three columns indicate whether the layout objects
2871 will be visible in the positions shown at the head of the columns:
2873 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {yes} {yes} {yes}
2874 @headitem Function @tab Vector @tab Before @tab At no @tab After
2875 @headitem form @tab form @tab break @tab break @tab break
2877 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
2878 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
2879 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
2880 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
2881 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
2882 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
2883 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
2884 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
2887 The default settings of @code{break-visibility} depend on the
2888 layout object. The following table shows all the layout objects
2889 of interest which are affected by @code{break-visibility} and the
2890 default setting of this property:
2892 @multitable @columnfractions .3 .3 .4
2894 @headitem Layout object @tab Usual context @tab Default setting
2896 @c omit Ambitus as it appears not to be affected by break-visibility -td
2897 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
2898 @item @code{BarLine} @tab @code{Score} @tab calculated
2899 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
2900 @c omit the following item until it can be explained -td
2901 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
2902 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2903 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
2904 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
2905 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2906 @c omit KeyCancellation until it can be explained -td
2907 @c @item @code{KeyCancellation} @tab ?? @tab @code{begin-of-line-invisible}
2908 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
2909 @c omit LeftEdge until it can be explained -td
2910 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
2911 @item @code{OctavateEight} @tab @code{Staff} @tab @code{begin-of-line-visible}
2912 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
2913 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
2917 The example below shows the use of the vector form to control the
2918 visibility of barlines:
2920 @lilypond[quote,verbatim,relative=1,ragged-right]
2923 % Remove bar line at the end of the current line
2924 \once \override Score.BarLine #'break-visibility = #'#(#f #t #t)
2930 Although all three components of the vector used to override
2931 @code{break-visibility} must be present, not all of them are
2932 effective with every layout object, and some combinations may
2933 even give errors. The following limitations apply:
2936 @item Bar lines cannot be printed at start of line.
2937 @item A bar number cannot be printed at the start of the first
2938 line unless it is set to be different from 1.
2939 @item Clef -- see below
2940 @item Double percent repeats are either all printed or all
2941 suppressed. Use begin-of line-invisible to print and
2942 all-invisible to suppress.
2943 @item Key signature -- see below
2944 @item OctavateEight -- see below
2947 @node Special considerations
2948 @unnumberedsubsubsec Special considerations
2950 @strong{@emph{Visibility following explicit changes}}
2952 @cindex key signature, visibility following explicit change
2953 @cindex explicitKeySignatureVisibility
2954 @cindex clef, visibility following explicit change
2955 @cindex explicitClefVisibility
2957 The @code{break-visibility} property controls the visibility of
2958 key signatures and changes of clef only at the start of lines,
2959 i.e. after a break. It has no effect on the visibility of the
2960 key signature or clef following an explicit key change or an
2961 explicit clef change within or at the end of a line. In the
2962 following example the key signature following the explicit change
2963 to B-flat major is still visible, even though @code{all-invisible}
2966 @lilypond[quote,verbatim,relative=1,ragged-right]
2969 % Try to remove all key signatures
2970 \override Staff.KeySignature #'break-visibility = #all-invisible
2978 The visibility of such explicit key signature and clef changes is
2979 controlled by the @code{explicitKeySignatureVisibility} and
2980 @code{explicitClefVisibility} properties. These are the equivalent
2981 of the @code{break-visibility} property and both take a vector of
2982 three booleans or the predefined functions listed above, exactly like
2983 @code{break-visibility}. Both are properties of the Staff context,
2984 not the layout objects themselves, and so they are set using the
2985 @code{\set} command. Both are set by default to @code{all-visible}.
2986 These properties control only the visibility of key signatures and
2987 clefs resulting from explicit changes and do not affect key
2988 signatures and clefs at the beginning of lines;
2989 @code{break-visibility} must still be overridden in the appropriate
2990 object to remove these.
2992 @lilypond[quote,verbatim,relative=1,ragged-right]
2995 \set Staff.explicitKeySignatureVisibility = #all-invisible
2996 \override Staff.KeySignature #'break-visibility = #all-invisible
3003 @strong{@emph{Visibility of cautionary accidentals}}
3005 To remove the cautionary accidentals printed at an explicit key
3006 change, set the Staff context property @code{printKeyCancellation}
3009 @lilypond[quote,verbatim,relative=1,ragged-right]
3012 \set Staff.explicitKeySignatureVisibility = #all-invisible
3013 \set Staff.printKeyCancellation = ##f
3014 \override Staff.KeySignature #'break-visibility = #all-invisible
3021 With these overrides only the accidentals before the notes remain
3022 to indicate the change of key.
3024 @c TODO Add visibility of cautionary accidentals before notes
3026 @strong{@emph{Automatic bars}}
3028 @cindex automaticBars
3029 @cindex bar lines, suppressing
3031 As a special case, the printing of bar lines can also be turned off
3032 by setting the @code{automaticBars} property in the Score context.
3033 If set to @code{#f}, bar lines will not be printed automatically;
3034 they must be explicitly created with a @code{\bar} command. Unlike
3035 the @code{\cadenzaOn} predefined command, measures are still counted.
3036 Bar generation will resume according to that count if this property
3037 is later set to @code{#t}. When set to @code{#f}, line breaks can
3038 occur only at explicit @code{\bar} commands.
3042 @strong{@emph{Octavated clefs}}
3044 @cindex octavated clefs, visibility of
3045 @cindex visibility of octavated clefs
3046 @cindex clefs, visibility of octavation
3048 The small octavation symbol on octavated clefs is produced by the
3049 @code{OctavateEight} layout object. Its visibility is controlled
3050 independently from that of the @code{Clef} object, so it is
3051 necessary to apply any required @code{break-visibility} overrides
3052 to both the @code{Clef} and the @code{OctavateEight} layout objects
3053 to fully suppress such clef symbols at the start of each line.
3055 For explicit clef changes, the @code{explicitClefVisibility}
3056 property controls both the clef symbol and any octavation symbol
3062 @rlearning{Visibility and color of objects}
3066 @subsection Line styles
3068 Some performance indications, e.g., @i{rallentando} and
3069 @i{accelerando} and @i{trills} are written as text and are
3070 extended over many measures with lines, sometimes dotted or wavy.
3072 These all use the same routines as the glissando for drawing the
3073 texts and the lines, and tuning their behavior is therefore also
3074 done in the same way. It is done with a spanner, and the routine
3075 responsible for drawing the spanners is
3076 @code{ly:line-interface::print}. This routine determines the
3077 exact location of the two @i{span points} and draws a line
3078 between them, in the style requested.
3080 Here is an example showing the different line styles available,
3081 and how to tune them.
3083 @lilypond[relative=2,ragged-right,verbatim,quote]
3085 \once \override Glissando #'style = #'dashed-line
3087 \override Glissando #'style = #'dotted-line
3089 \override Glissando #'style = #'zigzag
3091 \override Glissando #'style = #'trill
3095 The locations of the end-points of the spanner are computed
3096 on-the-fly for every graphic object, but it is possible to
3100 @lilypond[relative=2,ragged-right,verbatim,quote]
3102 \once \override Glissando #'(bound-details right Y) = #-2
3106 The value for @code{Y} is set to @code{-2} for the right end
3107 point. The left side may be similarly adjusted by specifying
3108 @code{left} instead of @code{right}.
3110 If @code{Y} is not set, the value is computed from the vertical
3111 position of the left and right attachment points of the spanner.
3113 Other adjustments of spanners are possible, for details, see
3116 @node Rotating objects
3117 @subsection Rotating objects
3119 Both layout objects and elements of markup text can be rotated by
3120 any angle about any point, but the method of doing so differs.
3123 * Rotating layout objects::
3127 @node Rotating layout objects
3128 @unnumberedsubsubsec Rotating layout objects
3130 @cindex rotating objects
3131 @cindex objects, rotating
3133 All layout objects which support the @code{grob-interface} can be
3134 rotated by setting their @code{rotation} property. This takes a
3135 list of three items: the angle of rotation counter-clockwise,
3136 and the x and y coordinates of the point relative to the object's
3137 reference point about which the rotation is to be performed. The
3138 angle of rotation is specified in degrees and the coordinates in
3141 The angle of rotation and the coordinates of the rotation point must
3142 be determined by trial and error.
3144 @cindex hairpins, angled
3145 @cindex angled hairpins
3147 There are only a few situations where the rotation of layout
3148 objects is useful; the following example shows one situation where
3151 @lilypond[quote,verbatim,relative=1]
3153 \override Hairpin #'rotation = #'(20 -1 0)
3157 @node Rotating markup
3158 @unnumberedsubsubsec Rotating markup
3160 All markup text can be rotated to lie at any angle by prefixing it
3161 with the @code{\rotate} command. The command takes two arguments:
3162 the angle of rotation in degrees counter-clockwise and the text to
3163 be rotated. The extents of the text are not rotated: they take
3164 their values from the extremes of the x and y coordinates of the
3165 rotated text. In the following example the
3166 @code{outside-staff-priority} property for text is set to @code{#f}
3167 to disable the automatic collision avoidance, which would push some
3168 of the text too high.
3170 @lilypond[quote,verbatim,relative=1]
3171 \override TextScript #'outside-staff-priority = ##f
3172 g4^\markup { \rotate #30 "a G" }
3173 b^\markup { \rotate #30 "a B" }
3174 des^\markup { \rotate #30 "a D-Flat" }
3175 fis^\markup { \rotate #30 "an F-Sharp" }
3178 @node Advanced tweaks
3179 @section Advanced tweaks
3181 This section discusses various approaches to fine tuning the
3182 appearance of the printed score.
3185 * Aligning objects::
3186 * Vertical grouping of grobs::
3187 * Modifying stencils::
3188 * Modifying shapes::
3194 @rlearning{Tweaking output},
3195 @rlearning{Other sources of information}.
3198 @ref{Explaining the Internals Reference},
3199 @ref{Modifying properties}.
3202 @file{scm/@/define@/-grobs@/.scm}.
3205 @rlsr{Tweaks and overrides}.
3208 @rextend{Interfaces for programmers}.
3210 Internals Reference:
3211 @rinternals{All layout objects}.
3214 @node Aligning objects
3215 @subsection Aligning objects
3217 Graphical objects which support the @code{self-alignment-interface}
3218 and/or the @code{side-position-interface} can be aligned to a previously
3219 placed object in a variety of ways. For a list of these objects, see
3220 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3222 All graphical objects have a reference point, a horizontal extent and a
3223 vertical extent. The horizontal extent is a pair of numbers
3224 giving the displacements from the reference point of the left and
3225 right edges, displacements to the left being negative. The vertical
3226 extent is a pair of numbers giving the displacement from the reference
3227 point to the bottom and top edges, displacements down being negative.
3229 An object's position on a staff is given by the values of the
3230 @code{X-offset} and @code{Y-offset} properties. The value of
3231 @code{X-offset} gives the displacement from the X coordinate of
3232 the reference point of the parent object, and the value of
3233 @code{Y-offset} gives the displacement from the center line of the
3234 staff. The values of @code{X-offset} and @code{Y-offset} may
3235 be set directly or may be set to be calculated by procedures in order
3236 to achieve alignment with the parent object.
3238 @warning{Many objects have special positioning considerations which
3239 cause any setting of @code{X-offset} or @code{Y-offset} to be
3240 ignored or modified, even though the object supports the
3241 @code{self-alignment-interface}. Overriding the @code{X-offset}
3242 or @code{Y-offset} properties to a fixed value causes the respective
3243 @code{self-alignment} property to be disregarded.}
3245 For example, an accidental can be repositioned vertically by setting
3246 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3248 Rehearsal marks may be aligned with breakable objects such as bar
3249 lines, clef symbols, time signature symbols and key signatures. There
3250 are special properties to be found in the @code{break-aligned-interface}
3251 for positioning rehearsal marks on such objects.
3254 @ref{Using the break-alignable-interface},
3255 @rextend{Callback functions}.
3258 * Setting X-offset and Y-offset directly::
3259 * Using the side-position-interface::
3260 * Using the self-alignment-interface::
3261 * Using the break-alignable-interface::
3264 @node Setting X-offset and Y-offset directly
3265 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3267 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3268 properties of many objects. The following example shows three
3269 notes with the default fingering position and the positions with @code{X-offset}
3270 and @code{Y-offset} modified.
3272 @lilypond[verbatim,quote,relative=2]
3275 -\tweak #'X-offset #0
3276 -\tweak #'Y-offset #0
3279 -\tweak #'X-offset #-1
3280 -\tweak #'Y-offset #1
3286 @node Using the side-position-interface
3287 @unnumberedsubsubsec Using the @code{side-position-interface}
3289 An object which supports the @code{side-position-interface} can be
3290 placed next to its parent object so that
3291 the specified edges of the two objects touch. The object may be
3292 placed above, below, to the right or to the left of the parent.
3293 The parent cannot be specified; it is determined by the order of
3294 elements in the input stream. Most objects have the associated
3295 note head as their parent.
3297 The values of the @code{side-axis} and @code{direction} properties
3298 determine where the object is to be placed, as follows:
3300 @c TODO add an example of each to the table
3302 @multitable @columnfractions .3 .3 .3
3303 @headitem @code{side-axis} @tab @code{direction} @tab
3304 @headitem property @tab property @tab Placement
3306 @item @code{0} @tab @code{-1} @tab left
3307 @item @code{0} @tab @code{1} @tab right
3308 @item @code{1} @tab @code{-1} @tab below
3309 @item @code{1} @tab @code{1} @tab above
3313 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3314 the procedure @code{ly:side-position-interface::x-aligned-side}.
3315 This procedure will return the correct value of @code{X-offset} to
3316 place the object to the left or right side of the parent according
3317 to value of @code{direction}.
3319 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3320 the procedure @code{ly:side-position-interface::y-aligned-side}.
3321 This procedure will return the correct value of @code{Y-offset} to
3322 place the object to the top or bottom of the parent according
3323 to value of @code{direction}.
3325 @c TODO Add examples
3327 @node Using the self-alignment-interface
3328 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3330 @emph{Self-aligning objects horizontally}
3332 The horizontal alignment of an object which supports the
3333 @code{self-alignment-interface} is controlled by the value of
3334 the @code{self-alignment-X} property, provided the object's
3335 @code{X-offset} property is set to
3336 @code{ly:self-alignment-interface::x-aligned-on-self}.
3337 @code{self-alignment-X} may be given any
3338 real value, in units of half the total X extent of the
3339 object. Negative values move the object to the right, positive
3340 to the left. A value of @code{0} centers the object on the
3341 reference point of its parent, a value of @code{-1} aligns the
3342 left edge of the object on the reference point of its parent,
3343 and a value of @code{1} aligns the right edge of the object on the
3344 reference point of its parent. The symbols @code{LEFT},
3345 @code{CENTER} and @code{RIGHT} may be used instead of the values
3346 @code{-1, 0, 1} respectively.
3348 Normally the @code{\override} command would be used to modify the
3349 value of @code{self-alignment-X}, but the @code{\tweak} command
3350 can be used to separately align several annotations on a single
3353 @lilypond[quote,verbatim,relative=1]
3355 -\tweak #'self-alignment-X #-1
3357 -\tweak #'self-alignment-X #0
3359 -\tweak #'self-alignment-X #RIGHT
3361 -\tweak #'self-alignment-X #-2.5
3362 ^"aligned further to the right"
3365 @emph{Self-aligning objects vertically}
3367 Objects may be aligned vertically in an analogous way to aligning
3368 them horizontally if the @code{Y-offset} property is set to
3369 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3370 other mechanisms are often involved in vertical alignment: the
3371 value of @code{Y-offset} is just one variable taken into account.
3372 This may make adjusting the value of some objects tricky.
3373 The units are just half the vertical extent of the object, which
3374 is usually quite small, so quite large numbers may be required.
3375 A value of @code{-1} aligns the lower edge of the object with
3376 the reference point of the parent object, a value of @code{0}
3377 aligns the center of the object with the reference point of the
3378 parent, and a value of @code{1} aligns the top edge of the object
3379 with the reference point of the parent. The symbols @code{DOWN},
3380 @code{CENTER}, @code{UP} may be substituted for @code{-1, 0, 1}
3383 @emph{Self-aligning objects in both directions}
3385 By setting both @code{X-offset} and @code{Y-offset}, an object may
3386 be aligned in both directions simultaneously.
3388 The following example shows how to adjust a fingering mark so
3389 that it nestles close to the note head.
3391 @lilypond[quote,verbatim,relative=2]
3393 -\tweak #'self-alignment-X #0.5 % move horizontally left
3394 -\tweak #'Y-offset #ly:self-alignment-interface::y-aligned-on-self
3395 -\tweak #'self-alignment-Y #-1 % move vertically up
3400 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3402 @c Cannot document as they do not seem to operate consistently on all objects -td
3403 @c TODO investigate further
3405 The @code{aligned-on-parent} procedures are used in the same way
3406 as the @code{aligned-on-self} procedures, they difference being
3407 that they permit an object to be aligned with the @emph{edges} of
3408 the parent rather than the parent's reference point. The following
3409 example shows the difference:
3413 @lilypond[verbatim,quote]
3419 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3421 @c Cannot document as they do not seem to operate consistently on all objects -td
3422 @c TODO investigate further
3426 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3428 @node Using the break-alignable-interface
3429 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3431 @cindex align to objects
3432 @cindex break-align-symbols
3434 Rehearsal marks and bar numbers may be aligned with notation
3435 objects other than bar lines. These objects include @code{ambitus},
3436 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3437 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3438 @code{time-signature}.
3440 By default, rehearsal marks and bar numbers will be horizontally
3441 centered above the object:
3443 @lilypond[verbatim,quote,relative=1]
3444 % The rehearsal mark will be centered above the Clef
3445 \override Score.RehearsalMark #'break-align-symbols = #'(clef)
3450 % The rehearsal mark will be centered above the Time Signature
3451 \override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
3457 % The rehearsal mark will be centered above the Breath Mark
3458 \override Score.RehearsalMark #'break-align-symbols = #'(breathing-sign)
3467 A list of possible target alignment objects may be specified. If
3468 some of the objects are invisible at that point due to the setting
3469 of @code{break-visibility} or the explicit visibility settings for
3470 keys and clefs, the rehearsal mark or bar number is aligned to the
3471 first object in the list which is visible. If no objects in the
3472 list are visible the object is aligned to the bar line. If the bar
3473 line is invisible the object is aligned to the place where the bar
3476 @lilypond[verbatim,quote,relative=1]
3477 % The rehearsal mark will be centered above the Key Signature
3478 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3483 % The rehearsal mark will be centered above the Clef
3484 \set Staff.explicitKeySignatureVisibility = #all-invisible
3485 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3490 % The rehearsal mark will be centered above the Bar Line
3491 \set Staff.explicitKeySignatureVisibility = #all-invisible
3492 \set Staff.explicitClefVisibility = #all-invisible
3493 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3500 The alignment of the rehearsal mark relative to the notation object
3501 can be changed, as shown in the following example. In a score with
3502 multiple staves, this setting should be done for all the staves.
3504 @lilypond[verbatim,quote,relative=1]
3505 % The RehearsalMark will be centered above the Key Signature
3506 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3512 % The RehearsalMark will be aligned with the left edge of the Key Signature
3513 \once \override Score.KeySignature #'break-align-anchor-alignment = #LEFT
3517 % The RehearsalMark will be aligned with the right edge of the Key Signature
3518 \once \override Score.KeySignature #'break-align-anchor-alignment = #RIGHT
3524 The rehearsal mark can also be offset to the right or left of the left
3525 edge by an arbitrary amount. The units are staff-spaces:
3527 @lilypond[verbatim,quote,relative=1]
3528 % The RehearsalMark will be aligned with the left edge of the Key Signature
3529 % and then shifted right by 3.5 staff-spaces
3530 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3531 \once \override Score.KeySignature #'break-align-anchor = #3.5
3535 % The RehearsalMark will be aligned with the left edge of the Key Signature
3536 % and then shifted left by 2 staff-spaces
3537 \once \override Score.KeySignature #'break-align-anchor = #-2
3544 @node Vertical grouping of grobs
3545 @subsection Vertical grouping of grobs
3547 @c TODO Expand this section
3549 The VerticalAlignment and VerticalAxisGroup grobs work together.
3550 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3551 etc. VerticalAlignment then vertically aligns the different grobs
3552 grouped together by VerticalAxisGroup. There is usually only one
3553 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3557 @node Modifying stencils
3558 @subsection Modifying stencils
3560 All layout objects have a @code{stencil} property which is part of
3561 the @code{grob-interface}. By default, this property is usually
3562 set to a function specific to the object that is tailor-made to
3563 render the symbol which represents it in the output. For example,
3564 the standard setting for the @code{stencil} property of the
3565 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3567 The standard symbol for any object can be replaced by modifying the
3568 @code{stencil} property to reference a different, specially-written,
3569 procedure. This requires a high level of knowledge of the internal
3570 workings of LilyPond, but there is an easier way which can often
3571 produce adequate results.
3573 This is to set the @code{stencil} property to the procedure which
3574 prints text -- @code{ly:text-interface::print} -- and to add a
3575 @code{text} property to the object which is set to contain the
3576 markup text which produces the required symbol. Due to the
3577 flexibility of markup, much can be achieved -- see in particular
3578 @ref{Graphic notation inside markup}.
3580 The following example demonstrates this by changing the note head
3581 symbol to a cross within a circle.
3583 @lilypond[verbatim,quote]
3585 \once \override NoteHead #'stencil = #ly:text-interface::print
3586 \once \override NoteHead #'text = \markup {
3588 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3589 \musicglyph #"noteheads.s2cross"
3597 Any of the glyphs in the feta Font can be supplied to the
3598 @code{\musicglyph} markup command -- see @ref{The Feta font}.
3600 @c TODO Add inserting eps files or ref to later
3602 @c TODO Add inserting Postscript or ref to later
3607 @ref{Graphic notation inside markup},
3608 @ref{Formatting text},
3609 @ref{Text markup commands},
3610 @ref{The Feta font}.
3613 @node Modifying shapes
3614 @subsection Modifying shapes
3617 * Modifying ties and slurs::
3620 @node Modifying ties and slurs
3621 @unnumberedsubsubsec Modifying ties and slurs
3623 @cindex slurs, modifying
3624 @cindex ties, modifying
3625 @cindex Bézier curves
3626 @cindex Bézier control points
3628 Ties, slurs and phrasing slurs are drawn as third-order Bézier
3629 curves. If the shape of the tie or slur which is calculated
3630 automatically is not optimum, the shape may be modified manually by
3631 explicitly specifying the four control points required to define
3632 a third-order Bézier curve.
3634 Third-order or cubic Bézier curves are defined by four control
3635 points. The first and fourth control points are precisely the
3636 starting and ending points of the curve. The intermediate two
3637 control points define the shape. Animations showing how the curve
3638 is drawn can be found on the web, but the following description
3639 may be helpful. The curve starts from the first control point
3640 heading directly towards the second, gradually bending over to
3641 head towards the third and continuing to bend over to head towards
3642 the fourth, arriving there travelling directly from the third
3643 control point. The curve is entirely contained in the
3644 quadrilateral defined by the four control points.
3646 Here is an example of a case where the tie is not optimum, and
3647 where @code{\tieDown} would not help.
3649 @lilypond[verbatim,quote,relative=1]
3653 { r4 <g c,> <g c,> <g c,> }
3657 One way of improving this tie is to manually modify its control
3660 The coordinates of the Bézier control points are specified in units
3661 of staff-spaces. The X@tie{}coordinate is relative to the reference
3662 point of the note to which the tie or slur is attached, and the
3663 Y@tie{}coordinate is relative to the staff center line. The
3664 coordinates are entered as a list of four pairs of decimal numbers
3665 (reals). One approach is to estimate the coordinates of the two
3666 end points, and then guess the two intermediate points. The optimum
3667 values are then found by trial and error.
3669 It is useful to remember that a symmetric curve requires symmetric
3670 control points, and that Bézier curves have the useful property that
3671 transformations of the curve such as translation, rotation and
3672 scaling can be achieved by applying the same transformation to the
3673 curve's control points.
3675 For the example above the following override gives a satisfactory
3676 tie. Note the placement -- it has to be immediately before the note
3677 to which the start of the tie (or slur) is attached.
3679 @lilypond[verbatim,quote,relative=1]
3683 #'control-points = #'((1 . -1) (3 . 0.6) (12.5 . 0.6) (14.5 . -1))
3687 { r4 <g c,> <g c,> <g c,>4 }
3693 It is not possible to modify shapes of ties or slurs by changing
3694 the @code{control-points} property if there are more than one at
3695 the same musical moment, not even by using the @code{\tweak}
3696 command. However, the @code{tie-configuration} property of
3697 @code{TieColumn} can be overridden to set start line and direction
3698 of ties as required.
3703 @node Using music functions
3704 @section Using music functions
3706 @c TODO -- add @seealso, etc. to these subsections
3708 Where tweaks need to be reused with different music expressions,
3709 it is often convenient to make the tweak part of a @emph{music
3710 function}. In this section, we discuss only @emph{substitution}
3711 functions, where the object is to substitute a variable into a
3712 piece of LilyPond input code. Other more complex functions are
3713 described in @rextend{Music functions}.
3716 * Substitution function syntax::
3717 * Substitution function examples::
3720 @node Substitution function syntax
3721 @subsection Substitution function syntax
3723 Making a function that substitutes a variable into LilyPond
3724 code is easy. The general form of these functions is
3728 #(define-music-function
3729 (parser location @var{arg1} @var{arg2} @dots{})
3730 (@var{type1?} @var{type2?} @dots{})
3732 @var{@dots{}music@dots{}}
3739 @multitable @columnfractions .33 .66
3740 @item @code{@var{argN}}
3741 @tab @var{n}th argument
3743 @item @code{@var{typeN?}}
3744 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
3745 must return @code{#t}.
3747 @item @code{@var{@dots{}music@dots{}}}
3748 @tab normal LilyPond input, using @code{$} to reference arguments
3753 The @code{parser} and @code{location} arguments are mandatory, and
3754 are used in some advanced situations as described in the
3755 @q{Extending} manual (see @rextend{Music functions}). For
3756 substitution functions, just be sure to include them.
3758 The list of type predicates is also required. Some of the most
3759 common type predicates used in music functions are:
3763 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
3773 For a list of available type predicates, see
3774 @ref{Predefined type predicates}. User-defined type predicates
3781 @ref{Predefined type predicates}.
3784 @rextend{Music functions}.
3787 @file{lily/music-scheme.cc},
3789 @file{scm/lily.scm}.
3792 @node Substitution function examples
3793 @subsection Substitution function examples
3795 This section introduces some substitution function examples.
3796 These are not intended to be exhaustive, but rather to demonstrate
3797 some of the possibilities of simple substitution functions.
3799 In the first example, a function is defined that simplifies
3800 setting the padding of a TextScript:
3802 @lilypond[quote,verbatim,ragged-right]
3804 #(define-music-function
3805 (parser location padding)
3808 \once \override TextScript #'padding = $padding
3812 c4^"piu mosso" b a b
3814 c4^"piu mosso" d e f
3816 c4^"piu mosso" fis a g
3820 In addition to numbers, we can use music expressions such
3821 as notes for arguments to music functions:
3823 @c TODO: use a better example (the music argument is redundant).
3825 @lilypond[quote,verbatim,ragged-right]
3827 #(define-music-function
3828 (parser location note)
3831 \once \override Voice.NoteHead #'stencil =
3832 #ly:text-interface::print
3833 \once \override Voice.NoteHead #'text =
3834 \markup \musicglyph #"custodes.mensural.u0"
3835 \once \override Voice.Stem #'stencil = ##f
3839 \relative c' { c4 d e f \custosNote g }
3842 Substitution functions with multiple arguments can be defined:
3844 @lilypond[quote,verbatim,ragged-right]
3846 #(define-music-function
3847 (parser location padding tempotext)
3850 \once \override Score.MetronomeMark #'padding = $padding
3851 \tempo \markup { \bold $tempotext }
3855 \tempo \markup { "Low tempo" }
3857 \tempoPadded #4.0 #"High tempo"
3864 TODO: add missing @@ref's here.