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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 @file{.ly} file with the hash
40 mark@tie{}@code{#}.@footnote{@rextend{Scheme tutorial}, contains a
41 short tutorial on entering numbers, lists, strings, and symbols in
46 * Interpretation contexts::
47 * Explaining the Internals Reference::
48 * Modifying properties::
49 * Useful concepts and properties::
51 * Using music functions::
55 @node Interpretation contexts
56 @section Interpretation contexts
58 This section describes what contexts are, and how to modify them.
61 * Contexts explained::
63 * Keeping contexts alive::
64 * Modifying context plug-ins::
65 * Changing context default settings::
66 * Defining new contexts::
73 @rlearning{Contexts and engravers}.
76 @file{ly/engraver-init.ly},
77 @file{ly/performer-init.ly}.
80 @rlsr{Contexts and engravers}.
83 @rinternals{Contexts},
84 @rinternals{Engravers and Performers}.
87 @node Contexts explained
88 @subsection Contexts explained
91 @c TODO Rethink and rewrite
93 >> > > - list of contexts: my *danger unmaintainable*
94 >> > > alarm just went off. I'm
96 I knew it would... And leaving out some of them is perfectly fine
98 I do think that a list like this, with the main contexts and a
100 description of what they do (perhaps also with a note about what
102 behavior is associated with each of them, but this may be
104 should be there, and then we could simply list the remaining ones
106 further explanation and with links to the IR.
109 @c TODO Improve layout, order and consistency of wording -td
111 @c TODO Add introduction which explains contexts in generality -td
113 @c TODO Describe propagation of property values -td
115 Contexts are arranged hierarchically:
118 * Score - the master of all contexts::
119 * Top-level contexts - staff containers::
120 * Intermediate-level contexts - staves::
121 * Bottom-level contexts - voices::
124 @node Score - the master of all contexts
125 @unnumberedsubsubsec Score - the master of all contexts
127 This is the top level notation context. No other context can
128 contain a Score context. By default the Score context handles
129 the administration of time signatures and makes sure that items
130 such as clefs, time signatures, and key-signatures are aligned
133 A Score context is instantiated implicitly when a
134 @code{\score @{@dots{}@}} or @code{\layout @{@dots{}@}} block is
137 @node Top-level contexts - staff containers
138 @unnumberedsubsubsec Top-level contexts - staff containers
140 @strong{@emph{StaffGroup}}
142 Groups staves while adding a bracket on the left side, grouping
143 the staves together. The bar lines of the contained staves are
144 connected vertically. @code{StaffGroup} only consists of a collection
145 of staves, with a bracket in front and spanning bar lines.
147 @strong{@emph{ChoirStaff}}
149 Identical to @code{StaffGroup} except that the bar lines of the
150 contained staves are not connected vertically.
152 @strong{@emph{GrandStaff}}
154 A group of staves, with a brace on the left side, grouping the
155 staves together. The bar lines of the contained staves are
156 connected vertically.
158 @strong{@emph{PianoStaff}}
160 Just like @code{GrandStaff}, but with support for instrument names
161 to the left of each system.
163 @node Intermediate-level contexts - staves
164 @unnumberedsubsubsec Intermediate-level contexts - staves
166 @strong{@emph{Staff}}
168 Handles clefs, bar lines, keys, accidentals. It can contain
169 @code{Voice} contexts.
171 @strong{@emph{RhythmicStaff}}
173 Like @code{Staff} but for printing rhythms. Pitches are ignored;
174 the notes are printed on one line.
176 @strong{@emph{TabStaff}}
178 Context for generating tablature. By default lays the music
179 expression out as a guitar tablature, printed on six lines.
181 @strong{@emph{DrumStaff}}
183 Handles typesetting for percussion. Can contain @code{DrumVoice}
185 @strong{@emph{VaticanaStaff}}
187 Same as @code{Staff}, except that it is designed for typesetting
188 a piece in gregorian style.
190 @strong{@emph{MensuralStaff}}
192 Same as @code{Staff}, except that it is designed for typesetting
193 a piece in mensural style.
195 @node Bottom-level contexts - voices
196 @unnumberedsubsubsec Bottom-level contexts - voices
198 Voice-level contexts initialise certain properties and start
199 appropriate engravers. Being bottom-level contexts, they cannot
200 contain other contexts.
202 @strong{@emph{Voice}}
204 Corresponds to a voice on a staff. This context handles the
205 conversion of dynamic signs, stems, beams, super- and sub-scripts,
206 slurs, ties, and rests. You have to instantiate this explicitly
207 if you require multiple voices on the same staff.
209 @strong{@emph{VaticanaVoice}}
211 Same as @code{Voice}, except that it is designed for typesetting
212 a piece in gregorian style.
214 @strong{@emph{MensuralVoice}}
216 Same as @code{Voice}, with modifications for typesetting a piece in
219 @strong{@emph{Lyrics}}
221 Corresponds to a voice with lyrics. Handles the printing of a
222 single line of lyrics.
224 @strong{@emph{DrumVoice}}
226 The voice context used in a percussion staff.
228 @strong{@emph{FiguredBass}}
230 The context in which @code{BassFigure} objects are created from
231 input entered in @code{\figuremode} mode.
233 @strong{@emph{TabVoice}}
235 The voice context used within a @code{TabStaff} context. Usually
236 left to be created implicitly.
238 @strong{@emph{CueVoice}}
240 A voice context used to render notes of a reduced size, intended
241 primarily for adding cue notes to a staff, see @ref{Formatting
242 cue notes}. Usually left to be created implicitly.
244 @strong{@emph{ChordNames}}
246 Typesets chord names.
251 Then the following, which I don't know what to do with:
253 * GregorianTranscriptionVoice
254 * GregorianTranscriptionStaff
257 Engraves fretboards from chords. Not easy... Not
259 There is now some documentation on FretBoards in the NR, under
260 instrument-specific notation -- cds.
265 Hard coded entry point for LilyPond. Cannot be tuned.
267 Silently discards all musical information given to this
272 @node Creating contexts
273 @subsection Creating contexts
275 @c TODO more complete descriptions rather than learning style
277 For scores with only one voice and one staff, contexts are
278 created automatically. For more complex scores, it is necessary to
279 create them by hand. There are three commands that do this.
284 The easiest command is @code{\new}, and it also the quickest to type.
285 It is prepended to a music expression, for example
289 @cindex Context, creating
292 \new @var{type} @var{music expression}
296 where @var{type} is a context name (like @code{Staff} or
297 @code{Voice}). This command creates a new context, and starts
298 interpreting the @var{music expression} with that.
300 A practical application of @code{\new} is a score with many
301 staves. Each part that should be on its own staff, is preceded with
304 @lilypond[quote,verbatim,relative=2,ragged-right]
311 The @code{\new} command may also give a name to the context,
314 \new @var{type} = @var{id} @var{music}
316 However, this user specified name is only used if there is no other
317 context already earlier with the same name.
323 Like @code{\new}, the @code{\context} command also directs a music
324 expression to a context object, but gives the context an explicit name. The
328 \context @var{type} = @var{id} @var{music}
331 This form will search for an existing context of type @var{type}
332 called @var{id}. If that context does not exist yet, a new
333 context with the specified name is created. This is useful if
334 the context is referred to later on. For example, when
335 setting lyrics the melody is in a named context
338 \context Voice = "@b{tenor}" @var{music}
342 so the texts can be properly aligned to its notes,
345 \new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
350 Another possible use of named contexts is funneling two different
351 music expressions into one context. In the following example,
352 articulations and notes are entered separately,
356 arts = @{ s4-. s4-> @}
359 They are combined by sending both to the same @code{Voice} context,
363 \new Staff \context Voice = "A" \music
364 \context Voice = "A" \arts
367 @lilypond[quote,ragged-right]
371 \new Staff \context Voice = "A" \music
372 \context Voice = "A" \arts
376 With this mechanism, it is possible to define an Urtext (original
377 edition), with the option to put several distinct articulations on the
380 @cindex creating contexts
383 The third command for creating contexts is
385 \context @var{type} @var{music}
390 This is similar to @code{\context} with @code{= @var{id}}, but matches
391 any context of type @var{type}, regardless of its given name.
393 This variant is used with music expressions that can be interpreted at
394 several levels. For example, the @code{\applyOutput} command (see
395 @rextend{Running a function on all layout objects}). Without an explicit
396 @code{\context}, it is usually applied to @code{Voice}
399 \applyOutput #'@var{context} #@var{function} % apply to Voice
402 To have it interpreted at the @code{Score} or @code{Staff} level use
406 \applyOutput #'Score #@var{function}
407 \applyOutput #'Staff #@var{function}
412 @node Keeping contexts alive
413 @subsection Keeping contexts alive
415 @cindex contexts, keeping alive
416 @cindex contexts, lifetime
418 Contexts are usually terminated at the first musical moment in
419 which they have nothing to do. So @code{Voice} contexts die as
420 soon as they contain no events; @code{Staff} contexts die as soon
421 as all the @code{Voice} contexts within them contain no events; etc.
422 This can cause difficulties if earlier contexts which have died
423 have to be referenced, for example, when changing staves with
424 @code{\change} commands, associating lyrics with a voice with
425 @code{\lyricsto} commands, or when adding further musical events to
428 There is an exception to this general rule: just one of the
429 @code{Voice} contexts in a @code{Staff} context or in a
430 @code{<<...>>} construct will always persist to the end of the
431 enclosing @code{Staff} context or @code{<<...>>} construct, even
432 though there may be periods when it has nothing to do. The context
433 to persist in this way will be the first one encountered in the
434 first enclosed @code{@{...@}} construct, ignoring any in enclosed
435 @code{<<...>>} constructs.
437 Any context can be kept alive by ensuring it has something to do at
438 every musical moment. @code{Staff} contexts are kept alive by
439 ensuring one of their voices is kept alive. One way of doing this
440 is to add spacer rests to a voice in parallel with the real music.
441 These need to be added to every @code{Voice} context which needs to
442 be kept alive. If several voices are to be used sporadically it is
443 safest to keep them all alive rather than attempting to rely on the
444 exceptions mentioned above.
446 In the following example, both voice A and voice B are kept alive
447 in this way for the duration of the piece:
449 @lilypond[quote,verbatim]
450 musicA = \relative c'' { d4 d d d }
451 musicB = \relative c'' { g4 g g g }
454 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
455 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
460 \context Voice = "A" {
464 \context Voice = "B" {
468 \context Voice = "A" { \musicA }
469 \context Voice = "B" { \musicB }
470 \context Voice = "A" { \musicA }
481 @cindex lyrics, aligning with sporadic melody
483 The following example shows how a sporadic melody line with lyrics
484 might be written using this approach. In a real situation the
485 melody and accompaniment would consist of several different
488 @lilypond[quote,verbatim]
489 melody = \relative c'' { a4 a a a }
490 accompaniment = \relative c' { d4 d d d }
491 words = \lyricmode { These words fol -- low the mel -- o -- dy }
494 \new Staff = "music" {
496 \new Voice = "melody" {
498 s1*4 % Keep Voice "melody" alive for 4 bars
501 \new Voice = "accompaniment" {
506 \context Voice = "melody" { \melody }
507 \context Voice = "accompaniment" { \accompaniment }
509 \context Voice = "accompaniment" { \accompaniment }
511 \context Voice = "melody" { \melody }
512 \context Voice = "accompaniment" { \accompaniment }
517 \new Lyrics \with { alignAboveContext = #"music" }
518 \lyricsto "melody" { \words }
523 An alternative way, which may be better in many circumstances, is
524 to keep the melody line alive by simply including spacer notes to
525 line it up correctly with the accompaniment:
527 @lilypond[quote,verbatim]
528 melody = \relative c'' {
534 accompaniment = \relative c' {
540 words = \lyricmode { These words fol -- low the mel -- o -- dy }
544 \new Staff = "music" {
546 \new Voice = "melody" {
550 \new Voice = "accompaniment" {
556 \new Lyrics \with { alignAboveContext = #"music" }
557 \lyricsto "melody" { \words }
563 @node Modifying context plug-ins
564 @subsection Modifying context plug-ins
566 @c TODO Should this be Modifying engravers or Modifying contexts?
568 Notation contexts (like @code{Score} and @code{Staff}) not only
570 they also contain plug-ins called @q{engravers} that create notation
571 elements. For example, the @code{Voice} context contains a
572 @code{Note_heads_engraver} and the @code{Staff} context contains a
573 @code{Key_signature_engraver}.
575 For a full a description of each plug-in, see
577 @rinternals{Engravers and Performers}.
580 Internals Reference @expansion{} Translation @expansion{} Engravers.
582 Every context described in
584 @rinternals{Contexts}
587 Internals Reference @expansion{} Translation @expansion{} Context.
589 lists the engravers used for that context.
592 It can be useful to shuffle around these plug-ins. This is done by
593 starting a new context with @code{\new} or @code{\context}, and
599 \new @var{context} \with @{
612 where the @dots{} should be the name of an engraver. Here is a simple
613 example which removes @code{Time_signature_engraver} and
614 @code{Clef_engraver} from a @code{Staff} context,
616 @lilypond[quote,relative=1,verbatim]
622 \remove "Time_signature_engraver"
623 \remove "Clef_engraver"
630 In the second staff there are no time signature or clef symbols. This
631 is a rather crude method of making objects disappear since it will affect
632 the entire staff. This method also influences the spacing, which may or
633 may not be desirable. More sophisticated methods of blanking objects
634 are shown in @rlearning{Visibility and color of objects}.
636 The next example shows a practical application. Bar lines and time
637 signatures are normally synchronized across the score. This is done
638 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
639 This plug-in keeps an administration of time signature, location
640 within the measure, etc. By moving these engraver from @code{Score} to
641 @code{Staff} context, we can have a score where each staff has its own
644 @cindex polymetric scores
645 @cindex Time signatures, multiple
647 @lilypond[quote,verbatim]
651 \consists "Timing_translator"
652 \consists "Default_bar_line_engraver"
658 \consists "Timing_translator"
659 \consists "Default_bar_line_engraver"
668 \remove "Timing_translator"
669 \remove "Default_bar_line_engraver"
677 Usually the order in which the engravers are specified
678 does not matter, but in a few special cases the order
679 is important, for example where one engraver writes
680 a property and another reads it, or where one engraver
681 creates a grob and another must process it. The order in
682 which the engravers are specified is the order in which
683 they are called to carry out their processing.
685 The following orderings are important: the
686 @code{Bar_engraver} must normally be first, and
687 the @code{New_fingering_engraver} must come before
688 the @code{Script_column_engraver}. There may be others
689 with ordering dependencies.
691 @node Changing context default settings
692 @subsection Changing context default settings
694 The context settings which are to be used by default in
695 @code{Score}, @code{Staff} and @code{Voice} contexts may be specified
696 in a @code{\layout} block, as illustrated in the following example.
697 The @code{\layout} block should be placed within the @code{\score}
698 block to which it is to apply, but outside any music.
700 Note that the @code{\set} command itself and the context must be
701 omitted when the context default values are specified in this way:
703 @lilypond[quote,verbatim]
706 a4^"Really small, thicker stems, no time signature" a a a
713 \override Stem #'thickness = #4.0
714 \remove "Time_signature_engraver"
720 In this example, the @code{\Staff} command specifies that the
721 subsequent specifications are to be applied to all staves within
724 Modifications can be made to the @code{Score} context or all
725 @code{Voice} contexts in a similar way.
729 It is not possible to collect context changes in a variable and apply
730 them to a @code{\context} definition by referring to that variable.
732 The @code{\Staff \RemoveEmptyStaves} will overwrite your current
733 @code{\Staff} settings. If you wish to change the defaults for a
734 staff which uses @code{\Staff \RemoveEmptyStaves}, you must do so
735 after calling @code{\Staff \RemoveEmptyStaves}, ie
740 \Staff \RemoveEmptyStaves
742 \override Stem #'thickness = #4.0
747 @c TODO: add \with in here.
751 @node Defining new contexts
752 @subsection Defining new contexts
754 @cindex contexts, defining new
755 @cindex engravers, including in contexts
770 Specific contexts, like @code{Staff} and @code{Voice}, are made of
771 simple building blocks. It is possible to create new types of
772 contexts with different combinations of engraver plug-ins.
774 The next example shows how to build a different type of
775 @code{Voice} context from scratch. It will be similar to
776 @code{Voice}, but only prints centered slash note heads. It can be used
777 to indicate improvisation in jazz pieces,
779 @lilypond[quote,ragged-right]
782 \type "Engraver_group"
783 \consists "Note_heads_engraver"
784 \consists "Rhythmic_column_engraver"
785 \consists "Text_engraver"
786 \consists Pitch_squash_engraver
787 squashedPosition = #0
788 \override NoteHead #'style = #'slash
789 \override Stem #'transparent = ##t
793 \accepts "ImproVoice"
797 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
798 c4 c^"undress" c_"while playing :)" c }
804 These settings are defined within a @code{\context} block inside a
805 @code{\layout} block,
815 In the following discussion, the example input shown should go in place
816 of the @dots{} in the previous fragment.
818 First it is necessary to define a name for the new context:
824 Since it is similar to the @code{Voice}, we want commands that work
825 on (existing) @code{Voice}s to remain working. This is achieved by
826 giving the new context an alias @code{Voice},
832 The context will print notes and instructive texts, so we need to add
833 the engravers which provide this functionality,
836 \consists Note_heads_engraver
837 \consists Text_engraver
840 but we only need this on the center line,
843 \consists Pitch_squash_engraver
844 squashedPosition = #0
847 The @rinternals{Pitch_squash_engraver} modifies note heads (created
848 by @rinternals{Note_heads_engraver}) and sets their vertical
849 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
852 The notes look like a slash, and have no stem,
855 \override NoteHead #'style = #'slash
856 \override Stem #'transparent = ##t
857 \override Flag #'transparent = ##t
860 All these plug-ins have to cooperate, and this is achieved with a
861 special plug-in, which must be marked with the keyword @code{\type}.
862 This should always be @code{Engraver_group}.
865 \type "Engraver_group"
873 \type "Engraver_group"
874 \consists "Note_heads_engraver"
875 \consists "Text_engraver"
876 \consists Pitch_squash_engraver
877 squashedPosition = #0
878 \override NoteHead #'style = #'slash
879 \override Stem #'transparent = ##t
880 \override Flag #'transparent = ##t
886 Contexts form hierarchies. We want to hang the @code{ImproVoice}
887 under @code{Staff}, just like normal @code{Voice}s. Therefore, we
888 modify the @code{Staff} definition with the @code{\accepts}
899 The opposite of @code{\accepts} is @code{\denies},
900 which is sometimes needed when reusing existing context definitions.
902 Putting both into a @code{\layout} block, like
912 \accepts "ImproVoice"
917 Then the output at the start of this subsection can be entered as
925 c c_"while playing :)"
932 @node Aligning contexts
933 @subsection Aligning contexts
935 New contexts may be aligned above or below existing contexts. This
936 could be useful in setting up a vocal staff (@rlearning{Vocal ensembles}) and
939 @c TODO Better example needed. Ref LM, and expand on it.
942 @funindex alignAboveContext
943 @funindex alignBelowContext
945 @lilypond[quote,ragged-right]
948 \relative c' \new Staff = "main" {
951 \new Staff \with { alignAboveContext = #"main" } \ossia
958 @cindex nested contexts
959 @cindex contexts, nested
964 Contexts like @code{PianoStaff} can contain other contexts
965 nested within them. Contexts which are acceptable for nesting
966 are defined by the @qq{accepts} list of a context. Contexts
967 which are not in this list are placed below the outer context
968 in the printed score.
969 For example, the @code{PianoStaff} context is defined by default
970 to accept @code{Staff} and @code{FiguredBass} contexts within
971 it, but not (for example) a @code{Lyrics} context. So in the
972 following structure the lyrics are placed below the piano staff
973 rather than between the two staves:
975 @lilypond[verbatim,quote,relative=1]
978 \new Staff { e4 d c2 }
979 \addlyrics { Three blind mice }
987 The @qq{accepts} list of a context can be modified to include
988 additional nested contexts, so if we wanted the lyrics to appear
989 between the two staves we could use:
991 @lilypond[verbatim,quote,relative=1]
992 \new PianoStaff \with { \accepts Lyrics }
994 \new Staff { e4 d c2 }
995 \addlyrics { Three blind mice }
1003 The opposite of @code{\accepts} is @code{\denies}; this removes a
1004 context from the @qq{accepts} list.
1006 @node Explaining the Internals Reference
1007 @section Explaining the Internals Reference
1011 * Navigating the program reference::
1012 * Layout interfaces::
1013 * Determining the grob property::
1014 * Naming conventions::
1017 @node Navigating the program reference
1018 @subsection Navigating the program reference
1020 @c TODO remove this (it's in the LM)
1021 @c Replace with more factual directions
1023 Suppose we want to move the fingering indication in the fragment
1026 @lilypond[quote,relative=2,verbatim]
1032 If you visit the documentation on fingering instructions (in
1033 @ref{Fingering instructions}), you will notice:
1038 Internals Reference: @rinternals{Fingering}.
1043 @c outdated info; probably will delete.
1045 This fragment points to two parts of the program reference: a page
1046 on @code{FingeringEvent} and one on @code{Fingering}.
1048 The page on @code{FingeringEvent} describes the properties of the music
1049 expression for the input @w{@code{-2}}. The page contains many links
1050 forward. For example, it says
1053 Accepted by: @rinternals{Fingering_engraver},
1057 That link brings us to the documentation for the Engraver, the
1061 This engraver creates the following layout objects: @rinternals{Fingering}.
1064 In other words, once the @code{FingeringEvent}s are interpreted, the
1065 @code{Fingering_engraver} plug-in will process them.
1069 @c I can't figure out what this is supposed to mean. -gp
1071 The @code{Fingering_engraver} is also listed to create
1072 @rinternals{Fingering} objects,
1074 @c old info? it doesn't make any sense to me with our current docs.
1076 second bit of information listed under @b{See also} in the Notation
1081 The programmer's reference is available as an HTML document. It is
1082 highly recommended that you read it in HTML form, either online or
1083 by downloading the HTML documentation. This section will be much more
1084 difficult to understand if you are using the
1088 Follow the link to @rinternals{Fingering}. At the top of the
1092 Fingering objects are created by: @rinternals{Fingering_engraver} and
1093 @rinternals{New_fingering_engraver}.
1096 By following related links inside the program reference, we can follow the
1097 flow of information within the program:
1101 @item @rinternals{Fingering}:
1102 @rinternals{Fingering} objects are created by:
1103 @rinternals{Fingering_engraver}
1105 @item @rinternals{Fingering_engraver}:
1106 Music types accepted: @rinternals{fingering-event}
1108 @item @rinternals{fingering-event}:
1109 Music event type @code{fingering-event} is in Music expressions named
1110 @rinternals{FingeringEvent}
1113 This path goes against the flow of information in the program: it
1114 starts from the output, and ends at the input event. You could
1115 also start at an input event, and read with the flow of
1116 information, eventually ending up at the output object(s).
1118 The program reference can also be browsed like a normal document. It
1119 contains chapters on
1121 @rinternals{Music definitions},
1124 @code{Music definitions}
1126 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1127 chapter lists all the definitions used and all properties that may be
1131 @node Layout interfaces
1132 @subsection Layout interfaces
1134 @cindex interface, layout
1135 @cindex layout interface
1138 The HTML page that we found in the previous section describes the
1139 layout object called @rinternals{Fingering}. Such an object is a
1140 symbol within the score. It has properties that store numbers (like
1141 thicknesses and directions), but also pointers to related objects. A
1142 layout object is also called a @emph{Grob}, which is short for Graphical
1143 Object. For more details about Grobs, see @rinternals{grob-interface}.
1145 The page for @code{Fingering} lists the definitions for the
1146 @code{Fingering} object. For example, the page says
1149 @code{padding} (dimension, in staff space):
1155 which means that the number will be kept at a distance of at least 0.5
1159 Each layout object may have several functions as a notational or
1160 typographical element. For example, the Fingering object
1161 has the following aspects
1165 Its size is independent of the horizontal spacing, unlike slurs or beams.
1168 It is a piece of text. Granted, it is usually a very short text.
1171 That piece of text is typeset with a font, unlike slurs or beams.
1174 Horizontally, the center of the symbol should be aligned to the
1175 center of the note head.
1178 Vertically, the symbol is placed next to the note and the staff.
1181 The vertical position is also coordinated with other superscript
1182 and subscript symbols.
1185 Each of these aspects is captured in so-called @emph{interface}s,
1186 which are listed on the @rinternals{Fingering} page at the bottom
1189 This object supports the following interfaces:
1190 @rinternals{item-interface},
1191 @rinternals{self-alignment-interface},
1192 @rinternals{side-position-interface}, @rinternals{text-interface},
1193 @rinternals{text-script-interface}, @rinternals{font-interface},
1194 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1197 Clicking any of the links will take you to the page of the respective
1198 object interface. Each interface has a number of properties. Some of
1199 them are not user-serviceable (@q{Internal properties}), but others
1202 We have been talking of @emph{the} @code{Fingering} object, but actually it
1203 does not amount to much. The initialization file (see
1204 @rlearning{Other sources of information})
1205 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1210 (avoid-slur . around)
1211 (slur-padding . 0.2)
1212 (staff-padding . 0.5)
1213 (self-alignment-X . 0)
1214 (self-alignment-Y . 0)
1215 (script-priority . 100)
1216 (stencil . ,ly:text-interface::print)
1217 (direction . ,ly:script-interface::calc-direction)
1218 (font-encoding . fetaText)
1219 (font-size . -5) ; don't overlap when next to heads.
1220 (meta . ((class . Item)
1221 (interfaces . (finger-interface
1223 text-script-interface
1225 side-position-interface
1226 self-alignment-interface
1227 item-interface))))))
1231 As you can see, the @code{Fingering} object is nothing more than a
1232 bunch of variable settings, and the webpage in the Internals Reference
1233 is directly generated from this definition.
1236 @node Determining the grob property
1237 @subsection Determining the grob property
1239 @c TODO remove this (it's in the LM)
1240 @c Replace with more factual directions
1242 Recall that we wanted to change the position of the @b{2} in
1244 @lilypond[quote,relative=2,verbatim]
1250 Since the @b{2} is vertically positioned next to its note, we have to
1251 meddle with the interface associated with this positioning. This is
1252 done using @code{side-position-interface}. The page for this interface
1256 @code{side-position-interface}
1258 Position a victim object (this one) next to other objects (the
1259 support). The property @code{direction} signifies where to put the
1260 victim object relative to the support (left or right, up or down?)
1265 Below this description, the variable @code{padding} is described as
1270 (dimension, in staff space)
1272 Add this much extra space between objects that are next to each other.
1276 By increasing the value of @code{padding}, we can move the
1277 fingering away from the note head. The following command inserts
1278 3 staff spaces of white
1279 between the note and the fingering:
1281 \once \override Voice.Fingering #'padding = #3
1284 Inserting this command before the Fingering object is created,
1285 i.e., before @code{c2}, yields the following result:
1287 @lilypond[quote,relative=2,verbatim]
1288 \once \override Voice.Fingering #'padding = #3
1295 In this case, the context for this tweak is @code{Voice}. This
1296 fact can also be deduced from the program reference, for the page for
1297 the @rinternals{Fingering_engraver} plug-in says
1300 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1304 @node Naming conventions
1305 @subsection Naming conventions
1307 Another thing that is needed, is an overview of the various naming
1311 @item scheme functions: lowercase-with-hyphens (incl. one-word
1313 @item scheme functions: ly:plus-scheme-style
1314 @item music events, music classes and music properties:
1316 @item Grob interfaces: scheme-style
1317 @item backend properties: scheme-style (but X and Y!)
1318 @item contexts (and MusicExpressions and grobs): Capitalized or
1320 @item context properties: lowercaseFollowedByCamelCase
1322 Capitalized_followed_by_lowercase_and_with_underscores
1325 Questions to be answered:
1327 @item Which of these are conventions and which are rules?
1328 @item Which are rules of the underlying language, and which are
1332 @node Modifying properties
1333 @section Modifying properties
1335 @c TODO change the menu and subsection node names to use
1336 @c backslash once the new macro to handle the refs
1337 @c is available. Need to find and change all refs at
1338 @c the same time. -td
1341 * Overview of modifying properties::
1343 * The override command::
1344 * The tweak command::
1345 * set versus override::
1346 * Modifying alists::
1350 @node Overview of modifying properties
1351 @subsection Overview of modifying properties
1353 Each context is responsible for creating certain types of graphical
1354 objects. The settings used for printing these objects are also stored by
1355 context. By changing these settings, the appearance of objects can be
1358 There are two different kinds of properties stored in contexts:
1359 context properties and grob properties. Context properties are
1360 properties that apply to the context as a whole and control
1361 how the context itself is displayed. In contrast, grob properties
1362 apply to specific grob types that will be displayed in the context.
1364 The @code{\set} and @code{\unset} commands are used to change values
1365 for context properties. The @code{\override} and @code{\revert}
1366 commands are used to change values for grob properties.
1369 The syntax for this is
1372 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1375 Here @var{name} is the name of a graphical object, like
1376 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1377 variable of the formatting system (@q{grob property} or @q{layout
1378 property}). The latter is a symbol, so it must be quoted. The
1379 subsection @ref{Modifying properties}, explains what to fill in
1380 for @var{name}, @var{property}, and @var{value}. Here we only
1381 discuss the functionality of this command.
1386 \override Staff.Stem #'thickness = #4.0
1390 makes stems thicker (the default is 1.3, with staff line thickness as a
1391 unit). Since the command specifies @code{Staff} as context, it only
1392 applies to the current staff. Other staves will keep their normal
1393 appearance. Here we see the command in action:
1395 @lilypond[quote,verbatim,relative=2]
1397 \override Staff.Stem #'thickness = #4.0
1403 The @code{\override} command changes the definition of the @code{Stem}
1404 within the current @code{Staff}. After the command is interpreted
1405 all stems are thickened.
1407 Analogous to @code{\set}, the @var{context} argument may be left out,
1408 causing the default context @code{Voice} to be used. Adding
1409 @code{\once} applies the change during one timestep only.
1411 @lilypond[quote,verbatim,relative=2]
1413 \once \override Stem #'thickness = #4.0
1418 The @code{\override} must be done before the object is
1419 started. Therefore, when altering @emph{Spanner} objects such as slurs
1420 or beams, the @code{\override} command must be executed at the moment
1421 when the object is created. In this example,
1423 @lilypond[quote,verbatim,relative=2]
1424 \override Slur #'thickness = #3.0
1426 \override Beam #'beam-thickness = #0.6
1431 the slur is fatter but the beam is not. This is because the command for
1432 @code{Beam} comes after the Beam is started, so it has no effect.
1434 Analogous to @code{\unset}, the @code{\revert} command for a context
1435 undoes an @code{\override} command; like with @code{\unset}, it only
1436 affects settings that were made in the same context. In other words, the
1437 @code{\revert} in the next example does not do anything.
1440 \override Voice.Stem #'thickness = #4.0
1441 \revert Staff.Stem #'thickness
1444 Some tweakable options are called @q{subproperties} and reside inside
1445 properties. To tweak those, use commands of the form
1447 @c leave this as a long long
1449 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1456 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1463 @rinternals{Backend},
1464 @rinternals{All layout objects},
1465 @rinternals{OverrideProperty},
1466 @rinternals{RevertProperty},
1467 @rinternals{PropertySet}.
1472 The back-end is not very strict in type-checking object properties.
1473 Cyclic references in Scheme values for properties can cause hangs
1474 or crashes, or both.
1478 @node The set command
1479 @subsection The @code{@bs{}set} command
1483 @cindex changing properties
1485 Each context has a set of @emph{properties}, variables contained
1486 in that context. Context properties are changed with the @code{\set}
1487 command, which has the following syntax:
1490 \set @var{context}.@var{property} = #@var{value}
1493 @var{value} is a Scheme object, which is why it must be preceded by
1494 the @code{#}@tie{}character.
1496 Contexts properties are usually named in
1497 @code{studlyCaps}. They mostly control the translation from
1498 music to notation, e.g. @code{localKeySignature} (for determining
1499 whether to print accidentals), or @code{measurePosition} (for
1500 determining when to print a bar line). Context properties can
1501 change value over time while interpreting a piece of music;
1502 @code{measurePosition} is an obvious example of
1503 this. Context properties are modified with @code{\set}.
1505 For example, multimeasure rests will be combined into a single bar
1506 if the context property @code{skipBars} is set to @code{#t}:
1508 @lilypond[quote,verbatim,relative=2]
1510 \set Score.skipBars = ##t
1514 If the @var{context} argument is left out, then the property will be
1515 set in the current bottom context (typically @code{ChordNames},
1516 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1518 @lilypond[quote,verbatim,relative=2]
1519 \set Score.autoBeaming = ##f
1523 \set autoBeaming = ##t
1531 The change is applied @q{on-the-fly}, during the music, so that the
1532 setting only affects the second group of eighth notes.
1534 Note that the bottom-most context does not always contain the property
1535 that you wish to change -- for example, attempting to set the
1536 @code{skipBars} property of the default bottom context, in this case
1537 @code{Voice}, will have no effect, because skipBars is a property of
1538 the @code{Score} context.
1540 @lilypond[quote,verbatim,relative=2]
1546 Contexts are hierarchical, so if an enclosing context was specified, for
1547 example @code{Staff}, then the change would also apply to all
1548 @code{Voice}s in the current staff.
1552 The @code{\unset} command:
1555 \unset @var{context}.@var{property}
1559 is used to remove the definition of @var{property} from
1560 @var{context}. This command removes
1561 the definition only if it is set in @var{context}.
1562 Properties that have been set in enclosing contexts will
1563 not be altered by an unset in an enclosed context:
1565 @lilypond[quote,verbatim,relative=2]
1566 \set Score.autoBeaming = ##t
1571 \unset Score.autoBeaming
1579 Like @code{\set}, the @var{context} argument does not have to be
1580 specified for a bottom context, so the two statements
1583 \set Voice.autoBeaming = ##t
1584 \set autoBeaming = ##t
1588 are equivalent if the current bottom context is @code{Voice}.
1592 Preceding a @code{\set} command by @code{\once} makes the
1593 setting apply to only a single time-step:
1595 @lilypond[quote,verbatim,relative=2]
1597 \once \set fontSize = #4.7
1602 A full description of all available context properties is in the
1603 internals reference, see
1605 @rinternals{Tunable context properties}.
1608 Translation @expansion{} Tunable context properties.
1613 Internals Reference:
1615 @rinternals{Tunable context properties}.
1618 @cindex grob properties
1619 @cindex properties, grob
1623 @node The override command
1624 @subsection The @code{\override} command
1626 There is a special type of context property: the grob
1627 description. Grob descriptions are named in @code{StudlyCaps}
1628 (starting with capital letters). They contain the
1629 @q{default settings} for a particular kind of grob as an
1630 association list. See @file{scm/define-grobs.scm}
1631 to see the settings for each grob description. Grob descriptions
1632 are modified with @code{\override}.
1634 @code{\override} is actually a shorthand;
1637 \override @var{context}.@var{GrobName} #'@var{property} = #@var{value}
1641 is more or less equivalent to
1643 @c leave this long line -gp
1645 \set @var{context}.@var{GrobName} =
1646 #(cons (cons '@var{property} @var{value})
1647 <previous value of @var{context}.@var{GrobName}>)
1650 The value of @code{context}.@code{GrobName} (the alist) is used to initialize
1651 the properties of individual grobs. Grobs have
1652 properties, named in Scheme style, with
1653 @code{dashed-words}. The values of grob properties change
1654 during the formatting process: formatting basically amounts
1655 to computing properties using callback functions.
1657 For example, we can increase the thickness of a note stem by
1658 overriding the @code{thickness} property of the @code{Stem}
1661 @lilypond[quote,verbatim,relative=2]
1663 \override Voice.Stem #'thickness = #3.0
1667 If no context is specified in an @code{\override}, the bottom
1670 @lilypond[quote,verbatim,relative=2]
1671 { \override Staff.Stem #'thickness = #3.0
1675 \override Stem #'thickness = #0.5
1685 @cindex reverting overrides
1686 @cindex overrides, reverting
1688 The effects of @code{\override} can be undone by @code{\revert}:
1690 @lilypond[quote,verbatim,relative=2]
1692 \override Voice.Stem #'thickness = #3.0
1694 \revert Voice.Stem #'thickness
1698 The effects of @code{\override} and @code{\revert} apply to all
1699 grobs in the affected context from the current time forward:
1701 @lilypond[quote,verbatim,relative=2]
1706 \override Staff.Stem #'thickness = #3.0
1710 \revert Staff.Stem #'thickness
1718 @cindex overriding for only one moment
1720 @code{\once} can be used with @code{\override}
1721 to affect only the current time step:
1723 @lilypond[quote,verbatim,relative=2]
1727 \override Stem #'thickness = #3.0
1731 \once \override Stem #'thickness = #3.0
1740 Commands which change output generally look like
1743 \override Voice.Stem #'thickness = #3.0
1747 To construct this tweak we must determine these bits of information:
1750 @item the context: here @code{Voice}.
1751 @item the layout object: here @code{Stem}.
1752 @item the layout property: here @code{thickness}.
1753 @item a sensible value: here @code{3.0}.
1756 Some tweakable options are called @q{subproperties} and reside inside
1757 properties. To tweak those, use commands in the form
1760 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1763 @cindex internal documentation
1764 @cindex finding graphical objects
1765 @cindex graphical object descriptions
1768 @cindex internal documentation
1770 For many properties, regardless of the data type of the property, setting the
1771 property to false (@code{#f}) will result in turning it off, causing
1772 LilyPond to ignore that property entirely. This is particularly useful for
1773 turning off grob properties which may otherwise be causing problems.
1775 We demonstrate how to glean this information from the notation manual
1776 and the program reference.
1781 Internals Reference:
1782 @rinternals{Backend}
1784 @node The tweak command
1785 @subsection The @code{\tweak} command
1790 Changing grob properties
1791 with @code{\override} causes the changes to apply to all of the
1792 given grobs in the context at the moment the change applies.
1793 Sometimes, however, it is desirable to have changes apply to just
1794 one grob, rather than to all grobs in the affected context. This is
1795 accomplished with the @code{\tweak} command, which has the following
1799 \tweak #'@code{grob-property} #@code{value}
1802 The @code{\tweak} command applies to the object that immediately
1803 follows @code{value} in the music stream.
1806 In some cases, it is possible to take a short-cut for tuning
1807 graphical objects. For objects that are created directly from
1808 an item in the input file, you can use the @code{\tweak} command.
1811 @lilypond[relative=2,verbatim,quote]
1816 \tweak #'duration-log #1
1819 -\tweak #'padding #8
1825 But the main use of the @code{\tweak} command is to modify just
1826 one of a number of notation elements which start at the same musical
1827 moment, like the notes of a chord, or tuplet brackets which start
1830 The @code{\tweak} command sets a property in the following object
1831 directly, without requiring the grob name or context to be
1832 specified. For this to work, it is necessary for the @code{\tweak}
1833 command to remain immediately adjacent to the object to which it is
1834 to apply after the input file has been converted to a music stream.
1835 This is often not the case, as many additional elements are inserted
1836 into the music stream implicitly. For example, when a note which is
1837 not part of a chord is processed, LilyPond implicitly inserts a
1838 @code{ChordEvent} event before the note, so separating the tweak
1839 from the note. However, if chord symbols are placed round the
1840 tweak and the note, the @code{\tweak} command comes after the
1841 @code{ChordEvent} in the music stream, so remaining adjacent to the
1842 note, and able to modify it.
1846 @lilypond[relative=2,verbatim,quote]
1847 <\tweak #'color #red c>4
1853 @lilypond[relative=2,verbatim,quote]
1854 \tweak #'color #red c4
1859 For an introduction to the syntax and uses of the tweak command
1860 see @rlearning{Tweaking methods}.
1862 When several similar items are placed at the same musical moment,
1863 the @code{\override} command cannot be used to modify just one of
1864 them -- this is where the @code{\tweak} command must be used.
1865 Items which may appear more than once at the same musical moment
1866 include the following:
1868 @c TODO expand to include any further uses of \tweak
1870 @item note heads of notes inside a chord
1871 @item articulation signs on a single note
1872 @item ties between notes in a chord
1873 @item tuplet brackets starting at the same time
1876 @c TODO add examples of these
1878 @cindex chord, modifying one note in
1880 In this example, the color of one note head and the type of another
1881 note head are modified within a single chord:
1883 @lilypond[relative=2,verbatim,quote]
1888 \tweak #'duration-log #1
1893 @code{\tweak} can be used to modify slurs:
1895 @lilypond[verbatim,quote,relative=1]
1896 c-\tweak #'thickness #5 ( d e f)
1900 For the @code{\tweak} command to work, it must
1901 remain immediately adjacent to the object to which it is
1902 to apply after the input file has been converted to a music stream.
1903 At times, LilyPond may insert additional items into the music stream
1904 during the parsing process. For example, when a note that is not
1905 explicitly part of a chord will be placed in a chord by LilyPond,
1906 so notes to be modified with @code{\tweak} must be placed inside
1909 @lilypond[relative=2,verbatim,quote]
1910 \tweak #'color #red c4
1911 <\tweak #'color #red c>4
1914 The @code{\tweak} command cannot be used to modify any item
1915 that does not appear explicitly in the input file. In particular
1916 it cannot be used to modify stems,
1917 beams or accidentals directly, since these are generated later by
1918 note heads, rather than by music elements in the input stream.
1919 Nor can @code{\tweak} be used to modify clefs or time
1920 signatures, since these become separated from any preceding
1921 @code{\tweak} command in the input stream by the automatic
1922 insertion of extra elements required to specify the context.
1924 Several @code{\tweak} commands may be placed before a
1925 notational element -- all affect it:
1927 @lilypond[verbatim,quote,relative=1]
1929 -\tweak #'style #'dashed-line
1930 -\tweak #'dash-fraction #0.2
1931 -\tweak #'thickness #3
1932 -\tweak #'color #red
1937 The music stream which is generated from a section of an input file,
1938 including any automatically inserted elements, may be examined,
1939 see @rextend{Displaying music expressions}. This may be helpful in
1940 determining what may be modified by a @code{\tweak} command, or
1941 in determining how to adjust the input to make a @code{\tweak}
1947 @rlearning{Tweaking methods}.
1950 @rextend{Displaying music expressions}.
1955 @cindex tweaks in a variable
1956 The @code{\tweak} command cannot be used inside a variable.
1958 @cindex tweaks in lyrics
1959 The @code{\tweak} commands cannot be used in @code{\lyricmode}.
1961 @cindex tweaking control points
1962 @cindex control points, tweaking
1964 The @code{\tweak} command will apply to only the first of several
1965 generated ties in a chord.
1967 @node set versus override
1968 @subsection @code{\set} vs. @code{\override}
1970 @c TODO -- This section is probably unnecessary now.
1973 We have seen two methods of changing properties: @code{\set} and
1974 @code{\override}. There are actually two different kinds of
1977 @code{fontSize} is a special property: it is equivalent to
1978 entering @code{\override ... #'font-size} for all pertinent
1979 objects. Since this is a common change, the special
1980 property (modified with @code{\set}) was created.
1985 @node Modifying alists
1986 @subsection Modifying alists
1988 Some user-configurable properties are internally represented as
1989 @emph{alists} (association lists), which store pairs of
1990 @emph{keys} and @emph{values}. The structure of an alist is:
1993 '((@var{key1} . @var{value1})
1994 (@var{key2} . @var{value2})
1995 (@var{key3} . @var{value3})
1999 If an alist is a grob property or @code{\paper} variable, its keys
2000 can be modified individually without affecting other keys.
2002 For example, to reduce the space between adjacent staves in a
2003 staff-group, use the @code{staff-staff-spacing} property of the
2004 @code{StaffGrouper} grob. The property is an alist with four
2005 keys: @code{basic-distance}, @code{minimum-distance},
2006 @code{padding}, and @code{stretchability}. The standard settings
2007 for this property are listed in the @qq{Backend} section of the
2008 Internals Reference (see @rinternals{StaffGrouper}):
2011 '((basic-distance . 9)
2012 (minimum-distance . 7)
2014 (stretchability . 5))
2017 One way to bring the staves closer together is by reducing the
2018 value of the @code{basic-distance} key (@code{9}) to match the
2019 value of @code{minimum-distance} (@code{7}). To modify a single
2020 key individually, use a @emph{nested declaration}:
2022 @lilypond[quote,verbatim]
2023 % default space between staves
2025 \new Staff { \clef treble c''1 }
2026 \new Staff { \clef bass c1 }
2029 % reduced space between staves
2030 \new PianoStaff \with {
2031 % this is the nested declaration
2032 \override StaffGrouper #'staff-staff-spacing #'basic-distance = #7
2034 \new Staff { \clef treble c''1 }
2035 \new Staff { \clef bass c1 }
2039 Using a nested declaration will update the specified key (such as
2040 @code{basic-distance} in the above example) without altering any
2041 other keys already set for the same property.
2043 Now suppose we want the staves to be as close as possible without
2044 overlapping. The simplest way to do this is to set all four alist
2045 keys to zero. However, it is not necessary to enter four nested
2046 declarations, one for each key. Instead, the property can be
2047 completely re-defined with one declaration, as an alist:
2049 @lilypond[quote,verbatim]
2050 \new PianoStaff \with {
2051 \override StaffGrouper #'staff-staff-spacing =
2052 #'((basic-distance . 0)
2053 (minimum-distance . 0)
2055 (stretchability . 0))
2057 \new Staff { \clef treble c''1 }
2058 \new Staff { \clef bass c1 }
2062 Note that any keys not explicitly listed in the alist definition
2063 will be reset to their @emph{default-when-unset} values. In the
2064 case of @code{staff-staff-spacing}, any unset key-values would be
2065 reset to zero (except @code{stretchability}, which takes the value
2066 of @code{basic-distance} when unset). Thus the following two
2067 declarations are equivalent:
2070 \override StaffGrouper #'staff-staff-spacing =
2071 #'((basic-distance . 7))
2073 \override StaffGrouper #'staff-staff-spacing =
2074 #'((basic-distance . 7)
2075 (minimum-distance . 0)
2077 (stretchability . 7))
2080 One (possibly unintended) consequence of this is the removal of
2081 any standard settings that are set in an initialization file and
2082 loaded each time an input file is compiled. In the above example,
2083 the standard settings for @code{padding} and
2084 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2085 are reset to their default-when-unset values (zero for both keys).
2086 Defining a property or variable as an alist (of any size) will
2087 always reset all unset key-values to their default-when-unset
2088 values. Unless this is the intended result, it is safer to update
2089 key-values individually with a nested declaration.
2091 @warning{Nested declarations will not work for context property
2092 alists (such as @code{beamExceptions}, @code{keySignature},
2093 @code{timeSignatureSettings}, etc.). These properties can only be
2094 modified by completely re-defining them as alists.}
2097 @node Useful concepts and properties
2098 @section Useful concepts and properties
2103 * Direction and placement::
2104 * Context layout order::
2105 * Distances and measurements::
2106 * Staff symbol properties::
2108 * Visibility of objects::
2110 * Rotating objects::
2114 @subsection Input modes
2116 The way in which the notation contained within an input file is
2117 interpreted is determined by the current input mode.
2121 This is activated with the @code{\chordmode} command, and causes
2122 input to be interpreted with the syntax of chord notation, see
2123 @ref{Chord notation}. Chords are rendered as notes on a staff.
2125 Chord mode is also activated with the @code{\chords} command.
2126 This also creates a new @code{ChordNames} context and
2127 causes the following input to be interpreted with the syntax of
2128 chord notation and rendered as chord names in the @code{ChordNames}
2129 context, see @ref{Printing chord names}.
2133 This is activated with the @code{\drummode} command, and causes
2134 input to be interpreted with the syntax of drum notation, see
2135 @ref{Basic percussion notation}.
2137 Drum mode is also activated with the @code{\drums} command.
2138 This also creates a new @code{DrumStaff} context and causes the
2139 following input to be interpreted with the syntax of drum notation
2140 and rendered as drum symbols on a drum staff, see @ref{Basic
2141 percussion notation}.
2143 @strong{Figure mode}
2145 This is activated with the @code{\figuremode} command, and causes
2146 input to be interpreted with the syntax of figured bass, see
2147 @ref{Entering figured bass}.
2149 Figure mode is also activated with the @code{\figures} command.
2150 This also creates a new @code{FiguredBass} context and causes the
2151 following input to be interpreted with the figured bass syntax
2152 and rendered as figured bass symbols in the @code{FiguredBass}
2153 context, see @ref{Introduction to figured bass}.
2155 @strong{Fret and tab modes}
2157 There are no special input modes for entering fret and tab symbols.
2159 To create tab diagrams, enter notes or chords in note mode and
2160 render them in a @code{TabStaff} context, see
2161 @ref{Default tablatures}.
2163 To create fret diagrams above a staff, you have two choices.
2164 You can either use the @code{FretBoards} context (see
2165 @ref{Automatic fret diagrams} or you can enter them as a markup
2166 above the notes using the @code{\fret-diagram} command (see
2167 @ref{Fret diagram markups}).
2169 @strong{Lyrics mode}
2171 This is activated with the @code{\lyricmode} command, and causes
2172 input to be interpreted as lyric syllables with optional durations
2173 and associated lyric modifiers, see @ref{Vocal music}.
2175 Lyric mode is also activated with the @code{\addlyrics} command.
2176 This also creates a new @code{Lyrics} context and an implicit
2177 @code{\lyricsto} command which associates the following lyrics
2178 with the preceding music.
2180 @strong{Markup mode}
2182 This is activated with the @code{\markup} command, and causes
2183 input to be interpreted with the syntax of markup, see
2184 @ref{Text markup commands}.
2186 @c silly work-around for texinfo broken-ness
2187 @c (@strong{Note...} causes a spurious cross-reference in Info)
2190 This is the default mode or it may be activated with the
2191 @code{\notemode} command. Input is interpreted as pitches,
2192 durations, markup, etc and typeset as musical notation on a staff.
2194 It is not normally necessary to specify note mode explicitly, but
2195 it may be useful to do so in certain situations, for example if you
2196 are in lyric mode, chord mode or any other mode and want to insert
2197 something that only can be done with note mode syntax.
2199 For example, to indicate dynamic markings for the verses of a
2200 choral pieces it is necessary to enter note mode to interpret
2203 @lilypond[verbatim,relative=2,quote]
2206 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2210 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2217 @node Direction and placement
2218 @subsection Direction and placement
2220 In typesetting music the direction and placement of many items is
2221 a matter of choice. For example, the stems of notes can
2222 be directed up or down; lyrics, dynamics, and other expressive
2223 marks may be placed above or below the staff; text may be aligned
2224 left, right or center; etc. Most of these choices may be left to
2225 be determined automatically by LilyPond, but in some cases it may
2226 be desirable to force a particular direction or placement.
2228 @strong{Articulation direction indicators}
2230 By default some directions are always up or always down (e.g.
2231 dynamics or fermata), while other things can alternate between
2232 up or down based on the stem direction (like slurs or accents).
2234 @c TODO Add table showing these
2236 The default action may be overridden by prefixing the articulation
2237 by a @emph{direction indicator}. Three direction indicators are
2238 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2239 and @code{-} (meaning @qq{use default direction}). The direction
2240 indicator can usually be omitted, in which case @code{-} is assumed,
2241 but a direction indicator is @strong{always} required before
2244 @item @code{\tweak} commands
2245 @item @code{\markup} commands
2246 @item @code{\tag} commands
2247 @item string markups, e.g. -"string"
2248 @item fingering instructions, e.g. @w{@code{-1}}
2249 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2252 Direction indicators affect only the next note:
2254 @lilypond[verbatim,quote,relative=2]
2261 @strong{The direction property}
2263 The position or direction of many layout objects is controlled
2264 by the @code{direction} property.
2266 The value of the @code{direction} property may be
2267 set to @code{1}, meaning @qq{up} or @qq{above}, or to @w{@code{-1}},
2268 meaning @qq{down} or @qq{below}. The symbols @code{UP} and
2269 @code{DOWN} may be used instead of @code{1} and @w{@code{-1}}
2270 respectively. The default direction may be specified by setting
2271 @code{direction} to @code{0} or @code{CENTER}. Alternatively,
2272 in many cases predefined commands
2273 exist to specify the direction. These are all of the form
2276 @code{\xxxUp}, @code{xxxDown}, @code{xxxNeutral}
2279 where @code{xxxNeutral} means @qq{use the default direction}.
2280 See @rlearning{Within-staff objects}.
2282 In a few cases, arpeggio being the only common example, the value
2283 of the @code{direction} property specifies whether the object
2284 is to be placed to the right or left of the parent object. In
2285 this case @w{@code{-1}} or @code{LEFT} means @qq{to the left} and
2286 @code{1} or @code{RIGHT} means @qq{to the right}. @code{0}
2287 or @code{CENTER} means @qq{use the default} direction, as before.
2290 These all have side-axis set to #X
2291 AmbitusAccidental - direction has no effect
2293 StanzaNumber - not tried
2294 TrillPitchAccidental - not tried
2295 TrillPitchGroup - not tried
2298 These indications affect all notes until they are cancelled.
2300 @lilypond[verbatim,quote,relative=2]
2310 @node Context layout order
2311 @subsection Context layout order
2313 @cindex contexts, layout order
2315 Contexts are normally positioned in a system from top to bottom
2316 in the order in which they are encountered in the input file. When
2317 contexts are nested, the outer context will include inner nested
2318 contexts as specified in the input file, provided the inner contexts
2319 are included in the outer context's @qq{accepts} list. Nested
2320 contexts which are not included in the outer context's @qq{accepts}
2321 list will be repositioned below the outer context rather than nested
2324 Note that a context will be silently created implicitly if a command
2325 is encountered when there is no suitable context available to
2326 contain it. This can give rise to unexpected new staves or scores.
2328 The default order in which contexts are laid out and the
2329 @qq{accepts} list can be changed, see @ref{Aligning contexts}.
2333 @rprogram{An extra staff appears}.
2336 @node Distances and measurements
2337 @subsection Distances and measurements
2339 @cindex distances, absolute
2340 @cindex distances, scaled
2347 Distances in LilyPond are of two types: absolute and scaled.
2349 Absolute distances are used for specifying margins, indents, and
2350 other page layout details, and are by default specified in
2351 millimeters. Distances may be specified in other units by
2352 following the quantity by @code{\mm}, @code{\cm},
2353 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2354 an inch). Page layout distances can also be specified in scalable
2355 units (see the following paragraph) by appending
2356 @code{\staff-space} to the quantity. Page layout is described in
2357 detail in @ref{Page layout}.
2359 Scaled distances are always specified in units of the staff-space
2360 or, rarely, the half staff-space. The staff-space is the distance
2361 between two adjacent staff lines. The default value can be changed
2362 globally by setting the global staff size, or it can be overridden
2363 locally by changing the @code{staff-space} property of
2364 @code{StaffSymbol}. Scaled distances automatically scale with any
2365 change to the either the global staff size or the
2366 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2367 automatically only with changes to the global staff size.
2368 The global staff size thus enables the overall size of a rendered
2369 score to be easily varied. For the methods of setting the global
2370 staff size see @ref{Setting the staff size}.
2374 If just a section of a score needs to be rendered to a different
2375 scale, for example an ossia section or a footnote, the global staff
2376 size cannot simply be changed as this would affect the entire score.
2377 In such cases the change in size is made by overriding both the
2378 @code{staff-space} property of @code{StaffSymbol} and the size of
2379 the fonts. A Scheme function, @code{magstep}, is available to
2380 convert from a font size change to the equivalent change in
2381 @code{staff-space}. For an explanation and an example of its use,
2382 see @rlearning{Length and thickness of objects}.
2387 @rlearning{Length and thickness of objects}.
2391 @ref{Setting the staff size}.
2394 @node Staff symbol properties
2395 @subsection Staff symbol properties
2397 @cindex adjusting staff symbol
2398 @cindex drawing staff symbol
2399 @cindex staff symbol, setting of
2401 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2402 @c Need to think of uses for these properties. Eg 'line-positions
2403 @c is used in a snippet to thicken centre line.
2404 @c If retained, add @ref to here in 1.6.2 -td
2406 The vertical position of staff lines and the number of staff lines
2407 can be defined at the same time. As the following example shows,
2408 note positions are not influenced by the staff line positions.
2410 @warning{The @code{'line-positions} property overrides the
2411 @code{'line-count} property. The number of staff lines is
2412 implicitly defined by the number of elements in the list of values
2413 for @code{'line-positions}.}
2415 @lilypond[verbatim,quote,relative=1]
2417 \override StaffSymbol #'line-positions = #'(7 3 0 -4 -6 -7)
2422 The width of a staff can be modified. The units are staff
2423 spaces. The spacing of objects inside the staff is not affected by
2426 @lilypond[verbatim,quote,relative=1]
2428 \override StaffSymbol #'width = #23
2435 @subsection Spanners
2437 Many objects of musical notation extend over several notes or even
2438 several bars. Examples are slurs, beams, tuplet brackets, volta
2439 repeat brackets, crescendi, trills, and glissandi. Such objects
2440 are collectively called @qq{spanners}, and have special properties to control
2441 their appearance and behaviour. Some of these properties are common
2442 to all spanners; others are restricted to a sub-set of the spanners.
2444 All spanners support the @code{spanner-interface}. A few, essentially
2445 those that draw a straight line between the two objects, support in
2446 addition the @code{line-spanner-interface}.
2448 @unnumberedsubsubsec Using the @code{spanner-interface}
2450 This interface provides two properties that apply to several spanners.
2452 @strong{@i{The @code{minimum-length} property}}
2454 The minimum length of the spanner is specified by the
2455 @code{minimum-length} property. Increasing this usually has the
2456 necessary effect of increasing the spacing of the notes between the
2457 two end points. However, this override has no effect on
2458 many spanners, as their length is determined by other considerations.
2459 A few examples where it is effective are shown below.
2469 Works as long as callback is made:
2473 Works not at all for:
2482 @lilypond[verbatim,quote,relative=2]
2485 % increase the length of the tie
2486 -\tweak #'minimum-length #5
2490 @lilypond[verbatim,quote,relative=2]
2492 \compressFullBarRests
2494 % increase the length of the rest bar
2495 \once \override MultiMeasureRest #'minimum-length = #20
2500 @lilypond[verbatim,quote,relative=2]
2502 % increase the length of the hairpin
2503 \override Hairpin #'minimum-length = #20
2507 This override can also be used to increase the length of slurs and
2510 @lilypond[verbatim,quote,relative=2]
2513 -\tweak #'minimum-length #5
2518 -\tweak #'minimum-length #5
2522 For some layout objects, the @code{minimum-length} property becomes
2523 effective only if the @code{set-spacing-rods} procedure is called
2524 explicitly. To do this, the @code{springs-and-rods} property should
2525 be set to @code{ly:spanner::set-spacing-rods}. For example,
2526 the minimum length of a glissando has no effect unless the
2527 @code{springs-and-rods} property is set:
2529 @lilypond[verbatim,quote,relative=1]
2533 % not effective alone
2534 \once \override Glissando #'minimum-length = #20
2537 % effective only when both overrides are present
2538 \once \override Glissando #'minimum-length = #20
2539 \once \override Glissando #'springs-and-rods = #ly:spanner::set-spacing-rods
2543 The same is true of the @code{Beam} object:
2545 @lilypond[verbatim,quote,relative=1]
2546 % not effective alone
2547 \once \override Beam #'minimum-length = #20
2550 % effective only when both overrides are present
2551 \once \override Beam #'minimum-length = #20
2552 \once \override Beam #'springs-and-rods = #ly:spanner::set-spacing-rods
2556 @strong{@i{The @code{to-barline} property}}
2558 The second useful property of the @code{spanner-interface} is
2559 @code{to-barline}. By default this is true, causing hairpins and
2560 other spanners which are terminated on the first note of a measure to
2561 end instead on the immediately preceding bar line. If set to false,
2562 the spanner will extend beyond the bar line and end on the note
2565 @lilypond[verbatim,quote,relative=2]
2566 a \< a a a a \! a a a \break
2567 \override Hairpin #'to-barline = ##f
2568 a \< a a a a \! a a a
2571 This property is not effective for all spanners. For example,
2572 setting it to @code{#t} has no effect on slurs or phrasing slurs
2573 or on other spanners for which terminating on the bar line would
2576 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2578 Objects which support the @code{line-spanner-interface} include
2581 @item @code{DynamicTextSpanner}
2582 @item @code{Glissando}
2583 @item @code{TextSpanner}
2584 @item @code{TrillSpanner}
2585 @item @code{VoiceFollower}
2588 The routine responsible for drawing the stencils for these spanners is
2589 @code{ly:line-interface::print}. This routine determines the
2590 exact location of the two end points and draws a line
2591 between them, in the style requested. The locations of the two
2592 end points of the spanner are computed on-the-fly, but it is
2593 possible to override their Y-coordinates. The
2594 properties which need to be specified are nested
2595 two levels down within the property hierarchy, but the syntax of
2596 the @code{\override} command is quite simple:
2598 @lilypond[relative=2,quote,verbatim]
2600 \once \override Glissando #'(bound-details left Y) = #3
2601 \once \override Glissando #'(bound-details right Y) = #-2
2605 The units for the @code{Y} property are @code{staff-space}s,
2606 with the center line of the staff being the zero point.
2607 For the glissando, this is the value for @code{Y} at the
2608 X-coordinate corresponding to the center point of each note head,
2609 if the line is imagined to be extended to there.
2611 If @code{Y} is not set, the value is computed from the vertical
2612 position of the corresponding attachment point of the spanner.
2614 In case of a line break, the values for the end points are
2615 specified by the @code{left-broken} and @code{right-broken}
2616 sub-lists of @code{bound-details}. For example:
2618 @lilypond[relative=2,ragged-right,verbatim,quote]
2619 \override Glissando #'breakable = ##t
2620 \override Glissando #'(bound-details right-broken Y) = #-3
2621 c1 \glissando \break
2626 A number of further properties of the @code{left} and
2627 @code{right} sub-lists of the @code{bound-details} property
2628 may be modified in the same way as @code{Y}:
2632 This sets the Y-coordinate of the end point, in @code{staff-space}s
2633 offset from the staff center line. By default, it is the center of
2634 the bound object, so a glissando points to the vertical center of
2637 For horizontal spanners, such as text spanners and trill spanners,
2638 it is hardcoded to 0.
2641 This determines where the line starts and ends in the X-direction,
2642 relative to the bound object. So, a value of @w{@code{-1}} (or
2643 @code{LEFT}) makes the line start/end at the left side of the note
2644 head it is attached to.
2647 This is the absolute X-coordinate of the end point. It is usually
2648 computed on the fly, and overriding it has little useful effect.
2651 Line spanners may have symbols at the beginning or end, which is
2652 contained in this sub-property. This is for internal use; it is
2653 recommended that @code{text} be used instead.
2656 This is a markup that is evaluated to yield the stencil. It is used
2657 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
2659 @lilypond[quote,ragged-right,relative=2,verbatim]
2660 \override TextSpanner #'(bound-details left text)
2661 = \markup { \small \bold Slower }
2662 c2\startTextSpan b c a\stopTextSpan
2665 @item stencil-align-dir-y
2666 @item stencil-offset
2667 Without setting one of these, the stencil is simply put at the
2668 end-point, centered on the line, as defined by the @code{X} and
2669 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
2670 or @code{stencil-offset} will move the symbol at the edge vertically
2671 relative to the end point of the line:
2673 @lilypond[relative=1,quote,verbatim]
2674 \override TextSpanner
2675 #'(bound-details left stencil-align-dir-y) = #-2
2676 \override TextSpanner
2677 #'(bound-details right stencil-align-dir-y) = #UP
2679 \override TextSpanner
2680 #'(bound-details left text) = #"ggg"
2681 \override TextSpanner
2682 #'(bound-details right text) = #"hhh"
2683 c4^\startTextSpan c c c \stopTextSpan
2686 Note that negative values move the text @emph{up}, contrary to the
2687 effect that might be expected, as a value of @w{@code{-1}} or
2688 @code{DOWN} means align the @emph{bottom} edge of the text with
2689 the spanner line. A value of @code{1} or @code{UP} aligns
2690 the top edge of the text with the spanner line.
2693 Setting this sub-property to @code{#t} produces an arrowhead at the
2697 This sub-property controls the space between the specified
2698 end point of the line and the actual end. Without padding, a
2699 glissando would start and end in the center of each note head.
2703 The music function @code{\endSpanners} terminates the spanner
2704 which starts on the immediately following note prematurely. It
2705 is terminated after exactly one note, or at the following bar line
2706 if @code{to-barline} is true and a bar line occurs before the next
2709 @lilypond[verbatim,quote,ragged-right,relative=2]
2711 c2 \startTextSpan c2 c2
2716 When using @code{\endSpanners} it is not necessary to close
2717 \startTextSpan with \stopTextSpan, nor is it necessary to close
2718 hairpins with @code{\!}.
2722 Internals Reference:
2723 @rinternals{TextSpanner},
2724 @rinternals{Glissando},
2725 @rinternals{VoiceFollower},
2726 @rinternals{TrillSpanner},
2727 @rinternals{line-spanner-interface}.
2730 @node Visibility of objects
2731 @subsection Visibility of objects
2733 @cindex objects, visibility of
2734 @cindex grobs, visibility of
2735 @cindex visibility of objects
2737 There are four main ways in which the visibility of layout objects
2738 can be controlled: their stencil can be removed, they can be made
2739 transparent, they can be colored white, or their
2740 @code{break-visibility} property can be overridden. The first
2741 three apply to all layout objects; the last to just a few -- the
2742 @emph{breakable} objects. The Learning Manual introduces these
2743 four techniques, see @rlearning{Visibility and color of objects}.
2745 There are also a few other techniques which are specific to
2746 certain layout objects. These are covered under Special
2750 * Removing the stencil::
2751 * Making objects transparent::
2752 * Painting objects white::
2753 * Using break-visibility::
2754 * Special considerations::
2758 @node Removing the stencil
2759 @unnumberedsubsubsec Removing the stencil
2761 @cindex stencil, removing
2763 Every layout object has a stencil property. By default this is set
2764 to the specific function which draws that object. If this property
2765 is overridden to @code{#f} no function will be called and the object
2766 will not be drawn. The default action can be recovered with
2769 @lilypond[quote,verbatim,relative=1]
2771 \override Score.BarLine #'stencil = ##f
2773 \revert Score.BarLine #'stencil
2777 @node Making objects transparent
2778 @unnumberedsubsubsec Making objects transparent
2780 @cindex transparent, making objects
2782 Every layout object has a transparent property which by default is
2783 set to @code{#f}. If set to @code{#t} the object still occupies
2784 space but is made invisible.
2786 @lilypond[quote,verbatim,relative=2]
2788 \once \override NoteHead #'transparent = ##t
2792 @node Painting objects white
2793 @unnumberedsubsubsec Painting objects white
2795 @cindex objects, coloring
2796 @cindex coloring objects
2798 @cindex printing order
2799 @cindex overwriting objects
2800 @cindex objects, overwriting
2801 @cindex grobs, overwriting
2803 Every layout object has a color property which by default is set
2804 to @code{black}. If this is overridden to @code{white} the object
2805 will be indistinguishable from the white background. However,
2806 if the object crosses other objects the color of the crossing
2807 points will be determined by the order in which they are drawn,
2808 and this may leave a ghostly image of the white object, as shown
2811 @lilypond[quote,verbatim,relative=2]
2812 \override Staff.Clef #'color = #white
2816 This may be avoided by changing the order of printing the objects.
2817 All layout objects have a @code{layer} property which should be set
2818 to an integer. Objects with the lowest value of @code{layer} are
2819 drawn first, then objects with progressively higher values are drawn,
2820 so objects with higher values overwrite objects with lower values.
2821 By default most objects are assigned a @code{layer} value of
2822 @code{1}, although a few objects, including @code{StaffSymbol} and
2823 @code{BarLine}, are assigned a value of @code{0}. The order of
2824 printing objects with the same value of @code{layer} is indeterminate.
2826 In the example above the white clef, with a default @code{layer}
2827 value of @code{1}, is drawn after the staff lines (default
2828 @code{layer} value @code{0}), so overwriting them. To change this,
2829 the @code{Clef} object must be given in a lower value of
2830 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
2832 @lilypond[quote,verbatim,relative=2]
2833 \override Staff.Clef #'color = #white
2834 \override Staff.Clef #'layer = #-1
2838 @node Using break-visibility
2839 @unnumberedsubsubsec Using break-visibility
2841 @c TODO Add making other objects breakable
2843 @cindex break-visibility
2845 Most layout objects are printed only once, but some like
2846 bar lines, clefs, time signatures and key signatures, may need
2847 to be printed twice when a line break occurs -- once at the end
2848 of the line and again at the start of the next line. Such
2849 objects are called @emph{breakable}, and have a property, the
2850 @code{break-visibility} property to control their visibility
2851 at the three positions in which they may appear -- at the
2852 start of a line, within a line if they are changed, and at the
2853 end of a line if a change takes place there.
2855 For example, the time signature
2856 by default will be printed at the start of the first line, but
2857 nowhere else unless it changes, when it will be printed at the
2858 point at which the change occurs. If this change occurs at the
2859 end of a line the new time signature will be printed at the start
2860 of the next line and a cautionary time signature will be printed
2861 at the end of the previous line as well.
2863 This behaviour is controlled by the @code{break-visibility}
2864 property, which is explained in
2865 @c Leave this ref on a newline - formats incorrectly otherwise -td
2866 @rlearning{Visibility and color of objects}. This property takes
2867 a vector of three booleans which, in order, determine whether the
2868 object is printed at the end of, within the body of, or at the
2869 beginning of a line. Or to be more precise, before a line break,
2870 where there is no line break, or after a line break.
2872 Alternatively, these eight combinations may be specified
2873 by pre-defined functions, defined in @file{scm/output-lib.scm},
2874 where the last three columns indicate whether the layout objects
2875 will be visible in the positions shown at the head of the columns:
2877 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {yes} {yes} {yes}
2878 @headitem Function @tab Vector @tab Before @tab At no @tab After
2879 @headitem form @tab form @tab break @tab break @tab break
2881 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
2882 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
2883 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
2884 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
2885 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
2886 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
2887 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
2888 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
2891 The default settings of @code{break-visibility} depend on the
2892 layout object. The following table shows all the layout objects
2893 of interest which are affected by @code{break-visibility} and the
2894 default setting of this property:
2896 @multitable @columnfractions .3 .3 .4
2898 @headitem Layout object @tab Usual context @tab Default setting
2900 @c omit Ambitus as it appears not to be affected by break-visibility -td
2901 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
2902 @item @code{BarLine} @tab @code{Score} @tab calculated
2903 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
2904 @c omit the following item until it can be explained -td
2905 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
2906 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2907 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
2908 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
2909 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2910 @c omit KeyCancellation until it can be explained -td
2911 @c @item @code{KeyCancellation} @tab ?? @tab @code{begin-of-line-invisible}
2912 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
2913 @c omit LeftEdge until it can be explained -td
2914 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
2915 @item @code{OctavateEight} @tab @code{Staff} @tab @code{begin-of-line-visible}
2916 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
2917 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
2921 The example below shows the use of the vector form to control the
2922 visibility of bar lines:
2924 @lilypond[quote,verbatim,relative=1,ragged-right]
2927 % Remove bar line at the end of the current line
2928 \once \override Score.BarLine #'break-visibility = #'#(#f #t #t)
2934 Although all three components of the vector used to override
2935 @code{break-visibility} must be present, not all of them are
2936 effective with every layout object, and some combinations may
2937 even give errors. The following limitations apply:
2940 @item Bar lines cannot be printed at start of line.
2941 @item A bar number cannot be printed at the start of the first
2942 line unless it is set to be different from 1.
2943 @item Clef -- see below
2944 @item Double percent repeats are either all printed or all
2945 suppressed. Use begin-of line-invisible to print and
2946 all-invisible to suppress.
2947 @item Key signature -- see below
2948 @item OctavateEight -- see below
2951 @node Special considerations
2952 @unnumberedsubsubsec Special considerations
2954 @strong{@emph{Visibility following explicit changes}}
2956 @cindex key signature, visibility following explicit change
2957 @cindex explicitKeySignatureVisibility
2958 @cindex clef, visibility following explicit change
2959 @cindex explicitClefVisibility
2961 The @code{break-visibility} property controls the visibility of
2962 key signatures and changes of clef only at the start of lines,
2963 i.e. after a break. It has no effect on the visibility of the
2964 key signature or clef following an explicit key change or an
2965 explicit clef change within or at the end of a line. In the
2966 following example the key signature following the explicit change
2967 to B-flat major is still visible, even though @code{all-invisible}
2970 @lilypond[quote,verbatim,relative=1,ragged-right]
2973 % Try to remove all key signatures
2974 \override Staff.KeySignature #'break-visibility = #all-invisible
2982 The visibility of such explicit key signature and clef changes is
2983 controlled by the @code{explicitKeySignatureVisibility} and
2984 @code{explicitClefVisibility} properties. These are the equivalent
2985 of the @code{break-visibility} property and both take a vector of
2986 three booleans or the predefined functions listed above, exactly like
2987 @code{break-visibility}. Both are properties of the Staff context,
2988 not the layout objects themselves, and so they are set using the
2989 @code{\set} command. Both are set by default to @code{all-visible}.
2990 These properties control only the visibility of key signatures and
2991 clefs resulting from explicit changes and do not affect key
2992 signatures and clefs at the beginning of lines;
2993 @code{break-visibility} must still be overridden in the appropriate
2994 object to remove these.
2996 @lilypond[quote,verbatim,relative=1,ragged-right]
2999 \set Staff.explicitKeySignatureVisibility = #all-invisible
3000 \override Staff.KeySignature #'break-visibility = #all-invisible
3007 @strong{@emph{Visibility of cautionary accidentals}}
3009 To remove the cautionary accidentals printed at an explicit key
3010 change, set the Staff context property @code{printKeyCancellation}
3013 @lilypond[quote,verbatim,relative=1,ragged-right]
3016 \set Staff.explicitKeySignatureVisibility = #all-invisible
3017 \set Staff.printKeyCancellation = ##f
3018 \override Staff.KeySignature #'break-visibility = #all-invisible
3025 With these overrides only the accidentals before the notes remain
3026 to indicate the change of key.
3028 @c TODO Add visibility of cautionary accidentals before notes
3030 @strong{@emph{Automatic bars}}
3032 @cindex automaticBars
3033 @cindex bar lines, suppressing
3035 As a special case, the printing of bar lines can also be turned off
3036 by setting the @code{automaticBars} property in the Score context.
3037 If set to @code{#f}, bar lines will not be printed automatically;
3038 they must be explicitly created with a @code{\bar} command. Unlike
3039 the @code{\cadenzaOn} predefined command, measures are still counted.
3040 Bar generation will resume according to that count if this property
3041 is later set to @code{#t}. When set to @code{#f}, line breaks can
3042 occur only at explicit @code{\bar} commands.
3046 @strong{@emph{Octavated clefs}}
3048 @cindex octavated clefs, visibility of
3049 @cindex visibility of octavated clefs
3050 @cindex clefs, visibility of octavation
3052 The small octavation symbol on octavated clefs is produced by the
3053 @code{OctavateEight} layout object. Its visibility is automatically
3054 inherited from the @code{Clef} object, so it is not necessary to apply
3055 any required @code{break-visibility} overrides to the @code{OctavateEight}
3056 layout objects to suppress octavation symbols for invisible clefs.
3058 For explicit clef changes, the @code{explicitClefVisibility}
3059 property controls both the clef symbol and any octavation symbol
3065 @rlearning{Visibility and color of objects}
3069 @subsection Line styles
3071 Some performance indications, e.g., @i{rallentando} and
3072 @i{accelerando} and @i{trills} are written as text and are
3073 extended over many measures with lines, sometimes dotted or wavy.
3075 These all use the same routines as the glissando for drawing the
3076 texts and the lines, and tuning their behavior is therefore also
3077 done in the same way. It is done with a spanner, and the routine
3078 responsible for drawing the spanners is
3079 @code{ly:line-interface::print}. This routine determines the
3080 exact location of the two @i{span points} and draws a line
3081 between them, in the style requested.
3083 Here is an example showing the different line styles available,
3084 and how to tune them.
3086 @lilypond[relative=2,ragged-right,verbatim,quote]
3088 \once \override Glissando #'style = #'dashed-line
3090 \override Glissando #'style = #'dotted-line
3092 \override Glissando #'style = #'zigzag
3094 \override Glissando #'style = #'trill
3098 The locations of the end-points of the spanner are computed
3099 on-the-fly for every graphic object, but it is possible to
3103 @lilypond[relative=2,ragged-right,verbatim,quote]
3105 \once \override Glissando #'(bound-details right Y) = #-2
3109 The value for @code{Y} is set to @w{@code{-2}} for the right end
3110 point. The left side may be similarly adjusted by specifying
3111 @code{left} instead of @code{right}.
3113 If @code{Y} is not set, the value is computed from the vertical
3114 position of the left and right attachment points of the spanner.
3116 Other adjustments of spanners are possible, for details, see
3119 @node Rotating objects
3120 @subsection Rotating objects
3122 Both layout objects and elements of markup text can be rotated by
3123 any angle about any point, but the method of doing so differs.
3126 * Rotating layout objects::
3130 @node Rotating layout objects
3131 @unnumberedsubsubsec Rotating layout objects
3133 @cindex rotating objects
3134 @cindex objects, rotating
3136 All layout objects which support the @code{grob-interface} can be
3137 rotated by setting their @code{rotation} property. This takes a
3138 list of three items: the angle of rotation counter-clockwise,
3139 and the x and y coordinates of the point relative to the object's
3140 reference point about which the rotation is to be performed. The
3141 angle of rotation is specified in degrees and the coordinates in
3144 The angle of rotation and the coordinates of the rotation point must
3145 be determined by trial and error.
3147 @cindex hairpins, angled
3148 @cindex angled hairpins
3150 There are only a few situations where the rotation of layout
3151 objects is useful; the following example shows one situation where
3154 @lilypond[quote,verbatim,relative=1]
3156 \override Hairpin #'rotation = #'(20 -1 0)
3160 @node Rotating markup
3161 @unnumberedsubsubsec Rotating markup
3163 All markup text can be rotated to lie at any angle by prefixing it
3164 with the @code{\rotate} command. The command takes two arguments:
3165 the angle of rotation in degrees counter-clockwise and the text to
3166 be rotated. The extents of the text are not rotated: they take
3167 their values from the extremes of the x and y coordinates of the
3168 rotated text. In the following example the
3169 @code{outside-staff-priority} property for text is set to @code{#f}
3170 to disable the automatic collision avoidance, which would push some
3171 of the text too high.
3173 @lilypond[quote,verbatim,relative=1]
3174 \override TextScript #'outside-staff-priority = ##f
3175 g4^\markup { \rotate #30 "a G" }
3176 b^\markup { \rotate #30 "a B" }
3177 des^\markup { \rotate #30 "a D-Flat" }
3178 fis^\markup { \rotate #30 "an F-Sharp" }
3181 @node Advanced tweaks
3182 @section Advanced tweaks
3184 This section discusses various approaches to fine tuning the
3185 appearance of the printed score.
3188 * Aligning objects::
3189 * Vertical grouping of grobs::
3190 * Modifying stencils::
3191 * Modifying shapes::
3197 @rlearning{Tweaking output},
3198 @rlearning{Other sources of information}.
3201 @ref{Explaining the Internals Reference},
3202 @ref{Modifying properties}.
3205 @file{scm/define-grobs.scm}.
3208 @rlsr{Tweaks and overrides}.
3211 @rextend{Interfaces for programmers}.
3213 Internals Reference:
3214 @rinternals{All layout objects}.
3217 @node Aligning objects
3218 @subsection Aligning objects
3220 Graphical objects which support the @code{self-alignment-interface}
3221 and/or the @code{side-position-interface} can be aligned to a previously
3222 placed object in a variety of ways. For a list of these objects, see
3223 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3225 All graphical objects have a reference point, a horizontal extent and a
3226 vertical extent. The horizontal extent is a pair of numbers
3227 giving the displacements from the reference point of the left and
3228 right edges, displacements to the left being negative. The vertical
3229 extent is a pair of numbers giving the displacement from the reference
3230 point to the bottom and top edges, displacements down being negative.
3232 An object's position on a staff is given by the values of the
3233 @code{X-offset} and @code{Y-offset} properties. The value of
3234 @code{X-offset} gives the displacement from the X coordinate of
3235 the reference point of the parent object, and the value of
3236 @code{Y-offset} gives the displacement from the center line of the
3237 staff. The values of @code{X-offset} and @code{Y-offset} may
3238 be set directly or may be set to be calculated by procedures in order
3239 to achieve alignment with the parent object.
3241 @warning{Many objects have special positioning considerations which
3242 cause any setting of @code{X-offset} or @code{Y-offset} to be
3243 ignored or modified, even though the object supports the
3244 @code{self-alignment-interface}. Overriding the @code{X-offset}
3245 or @code{Y-offset} properties to a fixed value causes the respective
3246 @code{self-alignment} property to be disregarded.}
3248 For example, an accidental can be repositioned vertically by setting
3249 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3251 Rehearsal marks may be aligned with breakable objects such as bar
3252 lines, clef symbols, time signature symbols and key signatures. There
3253 are special properties to be found in the @code{break-aligned-interface}
3254 for positioning rehearsal marks on such objects.
3257 @ref{Using the break-alignable-interface},
3258 @rextend{Callback functions}.
3261 * Setting X-offset and Y-offset directly::
3262 * Using the side-position-interface::
3263 * Using the self-alignment-interface::
3264 * Using the break-alignable-interface::
3267 @node Setting X-offset and Y-offset directly
3268 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3270 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3271 properties of many objects. The following example shows three
3272 notes with the default fingering position and the positions with @code{X-offset}
3273 and @code{Y-offset} modified.
3275 @lilypond[verbatim,quote,relative=2]
3278 -\tweak #'X-offset #0
3279 -\tweak #'Y-offset #0
3282 -\tweak #'X-offset #-1
3283 -\tweak #'Y-offset #1
3289 @node Using the side-position-interface
3290 @unnumberedsubsubsec Using the @code{side-position-interface}
3292 An object which supports the @code{side-position-interface} can be
3293 placed next to its parent object so that
3294 the specified edges of the two objects touch. The object may be
3295 placed above, below, to the right or to the left of the parent.
3296 The parent cannot be specified; it is determined by the order of
3297 elements in the input stream. Most objects have the associated
3298 note head as their parent.
3300 The values of the @code{side-axis} and @code{direction} properties
3301 determine where the object is to be placed, as follows:
3303 @c TODO add an example of each to the table
3305 @multitable @columnfractions .3 .3 .3
3306 @headitem @code{side-axis} @tab @code{direction} @tab
3307 @headitem property @tab property @tab Placement
3309 @item @code{0} @tab @code{-1} @tab left
3310 @item @code{0} @tab @code{1} @tab right
3311 @item @code{1} @tab @code{-1} @tab below
3312 @item @code{1} @tab @code{1} @tab above
3316 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3317 the procedure @code{ly:side-position-interface::x-aligned-side}.
3318 This procedure will return the correct value of @code{X-offset} to
3319 place the object to the left or right side of the parent according
3320 to value of @code{direction}.
3322 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3323 the procedure @code{ly:side-position-interface::y-aligned-side}.
3324 This procedure will return the correct value of @code{Y-offset} to
3325 place the object to the top or bottom of the parent according
3326 to value of @code{direction}.
3328 @c TODO Add examples
3330 @node Using the self-alignment-interface
3331 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3333 @emph{Self-aligning objects horizontally}
3335 The horizontal alignment of an object which supports the
3336 @code{self-alignment-interface} is controlled by the value of
3337 the @code{self-alignment-X} property, provided the object's
3338 @code{X-offset} property is set to
3339 @code{ly:self-alignment-interface::x-aligned-on-self}.
3340 @code{self-alignment-X} may be given any
3341 real value, in units of half the total X extent of the
3342 object. Negative values move the object to the right, positive
3343 to the left. A value of @code{0} centers the object on the
3344 reference point of its parent, a value of @w{@code{-1}} aligns the
3345 left edge of the object on the reference point of its parent,
3346 and a value of @code{1} aligns the right edge of the object on the
3347 reference point of its parent. The symbols @code{LEFT},
3348 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3349 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3351 Normally the @code{\override} command would be used to modify the
3352 value of @code{self-alignment-X}, but the @code{\tweak} command
3353 can be used to separately align several annotations on a single
3356 @lilypond[quote,verbatim,relative=1]
3358 -\tweak #'self-alignment-X #-1
3360 -\tweak #'self-alignment-X #0
3362 -\tweak #'self-alignment-X #RIGHT
3364 -\tweak #'self-alignment-X #-2.5
3365 ^"aligned further to the right"
3368 @emph{Self-aligning objects vertically}
3370 Objects may be aligned vertically in an analogous way to aligning
3371 them horizontally if the @code{Y-offset} property is set to
3372 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3373 other mechanisms are often involved in vertical alignment: the
3374 value of @code{Y-offset} is just one variable taken into account.
3375 This may make adjusting the value of some objects tricky.
3376 The units are just half the vertical extent of the object, which
3377 is usually quite small, so quite large numbers may be required.
3378 A value of @w{@code{-1}} aligns the lower edge of the object with
3379 the reference point of the parent object, a value of @code{0}
3380 aligns the center of the object with the reference point of the
3381 parent, and a value of @code{1} aligns the top edge of the object
3382 with the reference point of the parent. The symbols @code{DOWN},
3383 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3384 @code{0}, and @code{1}, respectively.
3386 @emph{Self-aligning objects in both directions}
3388 By setting both @code{X-offset} and @code{Y-offset}, an object may
3389 be aligned in both directions simultaneously.
3391 The following example shows how to adjust a fingering mark so
3392 that it nestles close to the note head.
3394 @lilypond[quote,verbatim,relative=2]
3396 -\tweak #'self-alignment-X #0.5 % move horizontally left
3397 -\tweak #'Y-offset #ly:self-alignment-interface::y-aligned-on-self
3398 -\tweak #'self-alignment-Y #-1 % move vertically up
3403 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3405 @c Cannot document as they do not seem to operate consistently on all objects -td
3406 @c TODO investigate further
3408 The @code{aligned-on-parent} procedures are used in the same way
3409 as the @code{aligned-on-self} procedures, they difference being
3410 that they permit an object to be aligned with the @emph{edges} of
3411 the parent rather than the parent's reference point. The following
3412 example shows the difference:
3416 @lilypond[verbatim,quote]
3422 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3424 @c Cannot document as they do not seem to operate consistently on all objects -td
3425 @c TODO investigate further
3429 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3431 @node Using the break-alignable-interface
3432 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3434 @cindex align to objects
3435 @cindex break-align-symbols
3437 Rehearsal marks and bar numbers may be aligned with notation
3438 objects other than bar lines. These objects include @code{ambitus},
3439 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3440 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3441 @code{time-signature}.
3443 By default, rehearsal marks and bar numbers will be horizontally
3444 centered above the object:
3446 @lilypond[verbatim,quote,relative=1]
3447 % The rehearsal mark will be centered above the Clef
3448 \override Score.RehearsalMark #'break-align-symbols = #'(clef)
3453 % The rehearsal mark will be centered above the Time Signature
3454 \override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
3460 % The rehearsal mark will be centered above the Breath Mark
3461 \override Score.RehearsalMark #'break-align-symbols = #'(breathing-sign)
3470 A list of possible target alignment objects may be specified. If
3471 some of the objects are invisible at that point due to the setting
3472 of @code{break-visibility} or the explicit visibility settings for
3473 keys and clefs, the rehearsal mark or bar number is aligned to the
3474 first object in the list which is visible. If no objects in the
3475 list are visible the object is aligned to the bar line. If the bar
3476 line is invisible the object is aligned to the place where the bar
3479 @lilypond[verbatim,quote,relative=1]
3480 % The rehearsal mark will be centered above the Key Signature
3481 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3486 % The rehearsal mark will be centered above the Clef
3487 \set Staff.explicitKeySignatureVisibility = #all-invisible
3488 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3493 % The rehearsal mark will be centered above the Bar Line
3494 \set Staff.explicitKeySignatureVisibility = #all-invisible
3495 \set Staff.explicitClefVisibility = #all-invisible
3496 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3503 The alignment of the rehearsal mark relative to the notation object
3504 can be changed, as shown in the following example. In a score with
3505 multiple staves, this setting should be done for all the staves.
3507 @lilypond[verbatim,quote,relative=1]
3508 % The RehearsalMark will be centered above the Key Signature
3509 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3515 % The RehearsalMark will be aligned with the left edge of the Key Signature
3516 \once \override Score.KeySignature #'break-align-anchor-alignment = #LEFT
3520 % The RehearsalMark will be aligned with the right edge of the Key Signature
3521 \once \override Score.KeySignature #'break-align-anchor-alignment = #RIGHT
3527 The rehearsal mark can also be offset to the right or left of the left
3528 edge by an arbitrary amount. The units are staff-spaces:
3530 @lilypond[verbatim,quote,relative=1]
3531 % The RehearsalMark will be aligned with the left edge of the Key Signature
3532 % and then shifted right by 3.5 staff-spaces
3533 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3534 \once \override Score.KeySignature #'break-align-anchor = #3.5
3538 % The RehearsalMark will be aligned with the left edge of the Key Signature
3539 % and then shifted left by 2 staff-spaces
3540 \once \override Score.KeySignature #'break-align-anchor = #-2
3547 @node Vertical grouping of grobs
3548 @subsection Vertical grouping of grobs
3550 @c TODO Expand this section
3552 The VerticalAlignment and VerticalAxisGroup grobs work together.
3553 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3554 etc. VerticalAlignment then vertically aligns the different grobs
3555 grouped together by VerticalAxisGroup. There is usually only one
3556 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3560 @node Modifying stencils
3561 @subsection Modifying stencils
3563 All layout objects have a @code{stencil} property which is part of
3564 the @code{grob-interface}. By default, this property is usually
3565 set to a function specific to the object that is tailor-made to
3566 render the symbol which represents it in the output. For example,
3567 the standard setting for the @code{stencil} property of the
3568 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3570 The standard symbol for any object can be replaced by modifying the
3571 @code{stencil} property to reference a different, specially-written,
3572 procedure. This requires a high level of knowledge of the internal
3573 workings of LilyPond, but there is an easier way which can often
3574 produce adequate results.
3576 This is to set the @code{stencil} property to the procedure which
3577 prints text -- @code{ly:text-interface::print} -- and to add a
3578 @code{text} property to the object which is set to contain the
3579 markup text which produces the required symbol. Due to the
3580 flexibility of markup, much can be achieved -- see in particular
3581 @ref{Graphic notation inside markup}.
3583 The following example demonstrates this by changing the note head
3584 symbol to a cross within a circle.
3586 @lilypond[verbatim,quote]
3588 \once \override NoteHead #'stencil = #ly:text-interface::print
3589 \once \override NoteHead #'text = \markup {
3591 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3592 \musicglyph #"noteheads.s2cross"
3600 Any of the glyphs in the feta Font can be supplied to the
3601 @code{\musicglyph} markup command -- see @ref{The Feta font}.
3603 @c TODO Add inserting eps files or ref to later
3605 @c TODO Add inserting Postscript or ref to later
3610 @ref{Graphic notation inside markup},
3611 @ref{Formatting text},
3612 @ref{Text markup commands},
3613 @ref{The Feta font}.
3616 @node Modifying shapes
3617 @subsection Modifying shapes
3620 * Modifying ties and slurs::
3623 @node Modifying ties and slurs
3624 @unnumberedsubsubsec Modifying ties and slurs
3626 @cindex slurs, modifying
3627 @cindex ties, modifying
3628 @cindex Bézier curves, control points
3629 @cindex control points, Bézier curves
3631 Ties, slurs and phrasing slurs are drawn as third-order Bézier
3632 curves. If the shape of the tie or slur which is calculated
3633 automatically is not optimum, the shape may be modified manually by
3634 explicitly specifying the four control points required to define
3635 a third-order Bézier curve.
3637 Third-order or cubic Bézier curves are defined by four control
3638 points. The first and fourth control points are precisely the
3639 starting and ending points of the curve. The intermediate two
3640 control points define the shape. Animations showing how the curve
3641 is drawn can be found on the web, but the following description
3642 may be helpful. The curve starts from the first control point
3643 heading directly towards the second, gradually bending over to
3644 head towards the third and continuing to bend over to head towards
3645 the fourth, arriving there travelling directly from the third
3646 control point. The curve is entirely contained in the
3647 quadrilateral defined by the four control points.
3649 Here is an example of a case where the tie is not optimum, and
3650 where @code{\tieDown} would not help.
3652 @lilypond[verbatim,quote,relative=1]
3656 { r4 <g c,> <g c,> <g c,> }
3660 One way of improving this tie is to manually modify its control
3663 The coordinates of the Bézier control points are specified in units
3664 of staff-spaces. The X@tie{}coordinate is relative to the reference
3665 point of the note to which the tie or slur is attached, and the
3666 Y@tie{}coordinate is relative to the staff center line. The
3667 coordinates are entered as a list of four pairs of decimal numbers
3668 (reals). One approach is to estimate the coordinates of the two
3669 end points, and then guess the two intermediate points. The optimum
3670 values are then found by trial and error.
3672 It is useful to remember that a symmetric curve requires symmetric
3673 control points, and that Bézier curves have the useful property that
3674 transformations of the curve such as translation, rotation and
3675 scaling can be achieved by applying the same transformation to the
3676 curve's control points.
3678 For the example above the following override gives a satisfactory
3679 tie. Note the placement -- it has to be immediately before the note
3680 to which the start of the tie (or slur) is attached.
3682 @lilypond[verbatim,quote,relative=1]
3686 #'control-points = #'((1 . -1) (3 . 0.6) (12.5 . 0.6) (14.5 . -1))
3690 { r4 <g c,> <g c,> <g c,> }
3695 It is not possible to modify shapes of ties or slurs by changing
3696 the @code{control-points} property if there are multiple ties or slurs
3697 at the same musical moment -- the @code{\tweak} command will also not
3698 work in this case. However, the @code{tie-configuration} property of
3699 @code{TieColumn} can be overridden to set start line and direction as
3703 Internals Reference:
3704 @rinternals{TieColumn}.
3707 @node Using music functions
3708 @section Using music functions
3710 @c TODO -- add @seealso, etc. to these subsections
3712 Where tweaks need to be reused with different music expressions,
3713 it is often convenient to make the tweak part of a @emph{music
3714 function}. In this section, we discuss only @emph{substitution}
3715 functions, where the object is to substitute a variable into a
3716 piece of LilyPond input code. Other more complex functions are
3717 described in @rextend{Music functions}.
3720 * Substitution function syntax::
3721 * Substitution function examples::
3724 @node Substitution function syntax
3725 @subsection Substitution function syntax
3727 Making a function that substitutes a variable into LilyPond
3728 code is easy. The general form of these functions is
3732 #(define-music-function
3733 (parser location @var{arg1} @var{arg2} @dots{})
3734 (@var{type1?} @var{type2?} @dots{})
3736 @var{@dots{}music@dots{}}
3743 @multitable @columnfractions .33 .66
3744 @item @code{@var{argN}}
3745 @tab @var{n}th argument
3747 @item @code{@var{typeN?}}
3748 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
3749 must return @code{#t}.
3751 @item @code{@var{@dots{}music@dots{}}}
3752 @tab normal LilyPond input, using @code{$} to reference arguments
3757 The @code{parser} and @code{location} arguments are mandatory, and
3758 are used in some advanced situations as described in the
3759 @q{Extending} manual (see @rextend{Music functions}). For
3760 substitution functions, just be sure to include them.
3762 The list of type predicates is also required. Some of the most
3763 common type predicates used in music functions are:
3767 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
3777 For a list of available type predicates, see
3778 @ref{Predefined type predicates}. User-defined type predicates
3785 @ref{Predefined type predicates}.
3788 @rextend{Music functions}.
3791 @file{lily/music-scheme.cc},
3793 @file{scm/lily.scm}.
3796 @node Substitution function examples
3797 @subsection Substitution function examples
3799 This section introduces some substitution function examples.
3800 These are not intended to be exhaustive, but rather to demonstrate
3801 some of the possibilities of simple substitution functions.
3803 In the first example, a function is defined that simplifies
3804 setting the padding of a TextScript:
3806 @lilypond[quote,verbatim,ragged-right]
3808 #(define-music-function
3809 (parser location padding)
3812 \once \override TextScript #'padding = $padding
3816 c4^"piu mosso" b a b
3818 c4^"piu mosso" d e f
3820 c4^"piu mosso" fis a g
3824 In addition to numbers, we can use music expressions such
3825 as notes for arguments to music functions:
3827 @c TODO: use a better example (the music argument is redundant).
3829 @lilypond[quote,verbatim,ragged-right]
3831 #(define-music-function
3832 (parser location note)
3835 \once \override Voice.NoteHead #'stencil =
3836 #ly:text-interface::print
3837 \once \override Voice.NoteHead #'text =
3838 \markup \musicglyph #"custodes.mensural.u0"
3839 \once \override Voice.Stem #'stencil = ##f
3843 \relative c' { c4 d e f \custosNote g }
3846 Substitution functions with multiple arguments can be defined:
3848 @lilypond[quote,verbatim,ragged-right]
3850 #(define-music-function
3851 (parser location padding tempotext)
3854 \once \override Score.MetronomeMark #'padding = $padding
3855 \tempo \markup { \bold $tempotext }
3859 \tempo \markup { "Low tempo" }
3861 \tempoPadded #4.0 #"High tempo"
3866 @c TODO: add appropriate @@ref's here.