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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::
67 * Context layout order::
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.
727 Context changes can be placed in a variable and applied to a
728 @code{\context} definition by prepending the modification with
730 @lilypond[quote,verbatim]
733 \override Stem #'thickness = #4.0
734 \remove "Time_signature_engraver"
739 \override Stem #'thickness = #-2.0
742 melody = \relative c'' {
751 s1*0^"Small, thicker stems, no time signature"
770 The @code{\Staff \RemoveEmptyStaves} will overwrite your current
771 @code{\Staff} settings. If you wish to change the defaults for a
772 staff which uses @code{\Staff \RemoveEmptyStaves}, you must do so
773 after calling @code{\Staff \RemoveEmptyStaves}, ie
778 \Staff \RemoveEmptyStaves
780 \override Stem #'thickness = #4.0
785 @c TODO: add \with in here.
789 @node Defining new contexts
790 @subsection Defining new contexts
792 @cindex contexts, defining new
793 @cindex engravers, including in contexts
808 Specific contexts, like @code{Staff} and @code{Voice}, are made of
809 simple building blocks. It is possible to create new types of
810 contexts with different combinations of engraver plug-ins.
812 The next example shows how to build a different type of
813 @code{Voice} context from scratch. It will be similar to
814 @code{Voice}, but only prints centered slash note heads. It can be used
815 to indicate improvisation in jazz pieces,
817 @lilypond[quote,ragged-right]
820 \type "Engraver_group"
821 \consists "Note_heads_engraver"
822 \consists "Rhythmic_column_engraver"
823 \consists "Text_engraver"
824 \consists Pitch_squash_engraver
825 squashedPosition = #0
826 \override NoteHead #'style = #'slash
827 \override Stem #'transparent = ##t
828 \override Flag #'transparent = ##t
832 \accepts "ImproVoice"
836 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
837 c4 c^"undress" c_"while playing :)" c }
843 These settings are defined within a @code{\context} block inside a
844 @code{\layout} block,
854 In the following discussion, the example input shown should go in place
855 of the @dots{} in the previous fragment.
857 First it is necessary to define a name for the new context:
863 Since it is similar to the @code{Voice}, we want commands that work
864 on (existing) @code{Voice}s to remain working. This is achieved by
865 giving the new context an alias @code{Voice},
871 The context will print notes and instructive texts, so we need to add
872 the engravers which provide this functionality,
875 \consists Note_heads_engraver
876 \consists Text_engraver
879 but we only need this on the center line,
882 \consists Pitch_squash_engraver
883 squashedPosition = #0
886 The @rinternals{Pitch_squash_engraver} modifies note heads (created
887 by @rinternals{Note_heads_engraver}) and sets their vertical
888 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
891 The notes look like a slash, and have no stem,
894 \override NoteHead #'style = #'slash
895 \override Stem #'transparent = ##t
896 \override Flag #'transparent = ##t
899 All these plug-ins have to cooperate, and this is achieved with a
900 special plug-in, which must be marked with the keyword @code{\type}.
901 This should always be @code{Engraver_group}.
904 \type "Engraver_group"
912 \type "Engraver_group"
913 \consists "Note_heads_engraver"
914 \consists "Text_engraver"
915 \consists Pitch_squash_engraver
916 squashedPosition = #0
917 \override NoteHead #'style = #'slash
918 \override Stem #'transparent = ##t
919 \override Flag #'transparent = ##t
925 Contexts form hierarchies. We want to hang the @code{ImproVoice}
926 under @code{Staff}, just like normal @code{Voice}s. Therefore, we
927 modify the @code{Staff} definition with the @code{\accepts}
938 The opposite of @code{\accepts} is @code{\denies},
939 which is sometimes needed when reusing existing context definitions.
941 Putting both into a @code{\layout} block, like
951 \accepts "ImproVoice"
956 Then the output at the start of this subsection can be entered as
964 c c_"while playing :)"
971 @node Context layout order
972 @subsection Context layout order
974 @cindex contexts, layout order
978 Contexts are normally positioned in a system from top to bottom
979 in the order in which they are encountered in the input file. When
980 contexts are nested, the outer context will include inner nested
981 contexts as specified in the input file, provided the inner contexts
982 are included in the outer context's @qq{accepts} list. Nested
983 contexts which are not included in the outer context's @qq{accepts}
984 list will be repositioned below the outer context rather than nested
987 The @qq{accepts} list of a context can be changed with the
988 @code{\accepts} and @code{\denies} commands. @code{\accepts} adds a
989 context to the @qq{accepts} list and @code{\denies} removes a context
990 from the list. For example, it would not normally be desirable for
991 chord names to be nested within a @code{Staff} context, so the
992 @code{ChordNames} context is not included by default in the @qq{accepts}
993 list of the @code{Staff} context, but if this were to be required it can
996 @lilypond[verbatim,quote]
1000 \chords { d1:m7 b1:min7.5- }
1005 @lilypond[verbatim,quote]
1009 \chords { d1:m7 b1:min7.5- }
1014 \accepts "ChordNames"
1020 @code{\denies} is mainly used when a new context is being based on
1021 another, but the required nesting differs. For example, the
1022 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1023 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1024 context in the @qq{accepts} list.
1026 Note that a context will be silently created implicitly if a command
1027 is encountered when there is no suitable context available to
1028 contain it. This can give rise to unexpected new staves or scores.
1032 @rprogram{An extra staff appears}.
1035 @file{ly/engraver-init.ly}.
1039 @node Explaining the Internals Reference
1040 @section Explaining the Internals Reference
1044 * Navigating the program reference::
1045 * Layout interfaces::
1046 * Determining the grob property::
1047 * Naming conventions::
1050 @node Navigating the program reference
1051 @subsection Navigating the program reference
1053 @c TODO remove this (it's in the LM)
1054 @c Replace with more factual directions
1056 Suppose we want to move the fingering indication in the fragment
1059 @lilypond[quote,relative=2,verbatim]
1065 If you visit the documentation on fingering instructions (in
1066 @ref{Fingering instructions}), you will notice:
1071 Internals Reference: @rinternals{Fingering}.
1076 @c outdated info; probably will delete.
1078 This fragment points to two parts of the program reference: a page
1079 on @code{FingeringEvent} and one on @code{Fingering}.
1081 The page on @code{FingeringEvent} describes the properties of the music
1082 expression for the input @w{@code{-2}}. The page contains many links
1083 forward. For example, it says
1086 Accepted by: @rinternals{Fingering_engraver},
1090 That link brings us to the documentation for the Engraver, the
1094 This engraver creates the following layout objects: @rinternals{Fingering}.
1097 In other words, once the @code{FingeringEvent}s are interpreted, the
1098 @code{Fingering_engraver} plug-in will process them.
1102 @c I can't figure out what this is supposed to mean. -gp
1104 The @code{Fingering_engraver} is also listed to create
1105 @rinternals{Fingering} objects,
1107 @c old info? it doesn't make any sense to me with our current docs.
1109 second bit of information listed under @b{See also} in the Notation
1114 The programmer's reference is available as an HTML document. It is
1115 highly recommended that you read it in HTML form, either online or
1116 by downloading the HTML documentation. This section will be much more
1117 difficult to understand if you are using the
1121 Follow the link to @rinternals{Fingering}. At the top of the
1125 Fingering objects are created by: @rinternals{Fingering_engraver} and
1126 @rinternals{New_fingering_engraver}.
1129 By following related links inside the program reference, we can follow the
1130 flow of information within the program:
1134 @item @rinternals{Fingering}:
1135 @rinternals{Fingering} objects are created by:
1136 @rinternals{Fingering_engraver}
1138 @item @rinternals{Fingering_engraver}:
1139 Music types accepted: @rinternals{fingering-event}
1141 @item @rinternals{fingering-event}:
1142 Music event type @code{fingering-event} is in Music expressions named
1143 @rinternals{FingeringEvent}
1146 This path goes against the flow of information in the program: it
1147 starts from the output, and ends at the input event. You could
1148 also start at an input event, and read with the flow of
1149 information, eventually ending up at the output object(s).
1151 The program reference can also be browsed like a normal document. It
1152 contains chapters on
1154 @rinternals{Music definitions},
1157 @code{Music definitions}
1159 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1160 chapter lists all the definitions used and all properties that may be
1164 @node Layout interfaces
1165 @subsection Layout interfaces
1167 @cindex interface, layout
1168 @cindex layout interface
1171 The HTML page that we found in the previous section describes the
1172 layout object called @rinternals{Fingering}. Such an object is a
1173 symbol within the score. It has properties that store numbers (like
1174 thicknesses and directions), but also pointers to related objects. A
1175 layout object is also called a @emph{Grob}, which is short for Graphical
1176 Object. For more details about Grobs, see @rinternals{grob-interface}.
1178 The page for @code{Fingering} lists the definitions for the
1179 @code{Fingering} object. For example, the page says
1182 @code{padding} (dimension, in staff space):
1188 which means that the number will be kept at a distance of at least 0.5
1192 Each layout object may have several functions as a notational or
1193 typographical element. For example, the Fingering object
1194 has the following aspects
1198 Its size is independent of the horizontal spacing, unlike slurs or beams.
1201 It is a piece of text. Granted, it is usually a very short text.
1204 That piece of text is typeset with a font, unlike slurs or beams.
1207 Horizontally, the center of the symbol should be aligned to the
1208 center of the note head.
1211 Vertically, the symbol is placed next to the note and the staff.
1214 The vertical position is also coordinated with other superscript
1215 and subscript symbols.
1218 Each of these aspects is captured in so-called @emph{interface}s,
1219 which are listed on the @rinternals{Fingering} page at the bottom
1222 This object supports the following interfaces:
1223 @rinternals{item-interface},
1224 @rinternals{self-alignment-interface},
1225 @rinternals{side-position-interface}, @rinternals{text-interface},
1226 @rinternals{text-script-interface}, @rinternals{font-interface},
1227 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1230 Clicking any of the links will take you to the page of the respective
1231 object interface. Each interface has a number of properties. Some of
1232 them are not user-serviceable (@q{Internal properties}), but others
1235 We have been talking of @emph{the} @code{Fingering} object, but actually it
1236 does not amount to much. The initialization file (see
1237 @rlearning{Other sources of information})
1238 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1243 (avoid-slur . around)
1244 (slur-padding . 0.2)
1245 (staff-padding . 0.5)
1246 (self-alignment-X . 0)
1247 (self-alignment-Y . 0)
1248 (script-priority . 100)
1249 (stencil . ,ly:text-interface::print)
1250 (direction . ,ly:script-interface::calc-direction)
1251 (font-encoding . fetaText)
1252 (font-size . -5) ; don't overlap when next to heads.
1253 (meta . ((class . Item)
1254 (interfaces . (finger-interface
1256 text-script-interface
1258 side-position-interface
1259 self-alignment-interface
1260 item-interface))))))
1264 As you can see, the @code{Fingering} object is nothing more than a
1265 bunch of variable settings, and the webpage in the Internals Reference
1266 is directly generated from this definition.
1269 @node Determining the grob property
1270 @subsection Determining the grob property
1272 @c TODO remove this (it's in the LM)
1273 @c Replace with more factual directions
1275 Recall that we wanted to change the position of the @b{2} in
1277 @lilypond[quote,relative=2,verbatim]
1283 Since the @b{2} is vertically positioned next to its note, we have to
1284 meddle with the interface associated with this positioning. This is
1285 done using @code{side-position-interface}. The page for this interface
1289 @code{side-position-interface}
1291 Position a victim object (this one) next to other objects (the
1292 support). The property @code{direction} signifies where to put the
1293 victim object relative to the support (left or right, up or down?)
1298 Below this description, the variable @code{padding} is described as
1303 (dimension, in staff space)
1305 Add this much extra space between objects that are next to each other.
1309 By increasing the value of @code{padding}, we can move the
1310 fingering away from the note head. The following command inserts
1311 3 staff spaces of white
1312 between the note and the fingering:
1314 \once \override Voice.Fingering #'padding = #3
1317 Inserting this command before the Fingering object is created,
1318 i.e., before @code{c2}, yields the following result:
1320 @lilypond[quote,relative=2,verbatim]
1321 \once \override Voice.Fingering #'padding = #3
1328 In this case, the context for this tweak is @code{Voice}. This
1329 fact can also be deduced from the program reference, for the page for
1330 the @rinternals{Fingering_engraver} plug-in says
1333 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1337 @node Naming conventions
1338 @subsection Naming conventions
1340 Another thing that is needed, is an overview of the various naming
1344 @item scheme functions: lowercase-with-hyphens (incl. one-word
1346 @item scheme functions: ly:plus-scheme-style
1347 @item music events, music classes and music properties:
1349 @item Grob interfaces: scheme-style
1350 @item backend properties: scheme-style (but X and Y!)
1351 @item contexts (and MusicExpressions and grobs): Capitalized or
1353 @item context properties: lowercaseFollowedByCamelCase
1355 Capitalized_followed_by_lowercase_and_with_underscores
1358 Questions to be answered:
1360 @item Which of these are conventions and which are rules?
1361 @item Which are rules of the underlying language, and which are
1365 @node Modifying properties
1366 @section Modifying properties
1368 @c TODO change the menu and subsection node names to use
1369 @c backslash once the new macro to handle the refs
1370 @c is available. Need to find and change all refs at
1371 @c the same time. -td
1374 * Overview of modifying properties::
1376 * The override command::
1377 * The tweak command::
1378 * set versus override::
1379 * Modifying alists::
1383 @node Overview of modifying properties
1384 @subsection Overview of modifying properties
1386 Each context is responsible for creating certain types of graphical
1387 objects. The settings used for printing these objects are also stored by
1388 context. By changing these settings, the appearance of objects can be
1391 There are two different kinds of properties stored in contexts:
1392 context properties and grob properties. Context properties are
1393 properties that apply to the context as a whole and control
1394 how the context itself is displayed. In contrast, grob properties
1395 apply to specific grob types that will be displayed in the context.
1397 The @code{\set} and @code{\unset} commands are used to change values
1398 for context properties. The @code{\override} and @code{\revert}
1399 commands are used to change values for grob properties.
1402 The syntax for this is
1405 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1408 Here @var{name} is the name of a graphical object, like
1409 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1410 variable of the formatting system (@q{grob property} or @q{layout
1411 property}). The latter is a symbol, so it must be quoted. The
1412 subsection @ref{Modifying properties}, explains what to fill in
1413 for @var{name}, @var{property}, and @var{value}. Here we only
1414 discuss the functionality of this command.
1419 \override Staff.Stem #'thickness = #4.0
1423 makes stems thicker (the default is 1.3, with staff line thickness as a
1424 unit). Since the command specifies @code{Staff} as context, it only
1425 applies to the current staff. Other staves will keep their normal
1426 appearance. Here we see the command in action:
1428 @lilypond[quote,verbatim,relative=2]
1430 \override Staff.Stem #'thickness = #4.0
1436 The @code{\override} command changes the definition of the @code{Stem}
1437 within the current @code{Staff}. After the command is interpreted
1438 all stems are thickened.
1440 Analogous to @code{\set}, the @var{context} argument may be left out,
1441 causing the default context @code{Voice} to be used. Adding
1442 @code{\once} applies the change during one timestep only.
1444 @lilypond[quote,verbatim,relative=2]
1446 \once \override Stem #'thickness = #4.0
1451 The @code{\override} must be done before the object is
1452 started. Therefore, when altering @emph{Spanner} objects such as slurs
1453 or beams, the @code{\override} command must be executed at the moment
1454 when the object is created. In this example,
1456 @lilypond[quote,verbatim,relative=2]
1457 \override Slur #'thickness = #3.0
1459 \override Beam #'beam-thickness = #0.6
1464 the slur is fatter but the beam is not. This is because the command for
1465 @code{Beam} comes after the Beam is started, so it has no effect.
1467 Analogous to @code{\unset}, the @code{\revert} command for a context
1468 undoes an @code{\override} command; like with @code{\unset}, it only
1469 affects settings that were made in the same context. In other words, the
1470 @code{\revert} in the next example does not do anything.
1473 \override Voice.Stem #'thickness = #4.0
1474 \revert Staff.Stem #'thickness
1477 Some tweakable options are called @q{subproperties} and reside inside
1478 properties. To tweak those, use commands of the form
1480 @c leave this as a long long
1482 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1489 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1496 @rinternals{Backend},
1497 @rinternals{All layout objects},
1498 @rinternals{OverrideProperty},
1499 @rinternals{RevertProperty},
1500 @rinternals{PropertySet}.
1505 The back-end is not very strict in type-checking object properties.
1506 Cyclic references in Scheme values for properties can cause hangs
1507 or crashes, or both.
1511 @node The set command
1512 @subsection The @code{@bs{}set} command
1516 @cindex changing properties
1518 Each context has a set of @emph{properties}, variables contained
1519 in that context. Context properties are changed with the @code{\set}
1520 command, which has the following syntax:
1523 \set @var{context}.@var{property} = #@var{value}
1526 @var{value} is a Scheme object, which is why it must be preceded by
1527 the @code{#}@tie{}character.
1529 Contexts properties are usually named in
1530 @code{studlyCaps}. They mostly control the translation from
1531 music to notation, e.g. @code{localKeySignature} (for determining
1532 whether to print accidentals), or @code{measurePosition} (for
1533 determining when to print a bar line). Context properties can
1534 change value over time while interpreting a piece of music;
1535 @code{measurePosition} is an obvious example of
1536 this. Context properties are modified with @code{\set}.
1538 For example, multimeasure rests will be combined into a single bar
1539 if the context property @code{skipBars} is set to @code{#t}:
1541 @lilypond[quote,verbatim,relative=2]
1543 \set Score.skipBars = ##t
1547 If the @var{context} argument is left out, then the property will be
1548 set in the current bottom context (typically @code{ChordNames},
1549 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1551 @lilypond[quote,verbatim,relative=2]
1552 \set Score.autoBeaming = ##f
1556 \set autoBeaming = ##t
1564 The change is applied @q{on-the-fly}, during the music, so that the
1565 setting only affects the second group of eighth notes.
1567 Note that the bottom-most context does not always contain the property
1568 that you wish to change -- for example, attempting to set the
1569 @code{skipBars} property of the default bottom context, in this case
1570 @code{Voice}, will have no effect, because skipBars is a property of
1571 the @code{Score} context.
1573 @lilypond[quote,verbatim,relative=2]
1579 Contexts are hierarchical, so if an enclosing context was specified, for
1580 example @code{Staff}, then the change would also apply to all
1581 @code{Voice}s in the current staff.
1585 The @code{\unset} command:
1588 \unset @var{context}.@var{property}
1592 is used to remove the definition of @var{property} from
1593 @var{context}. This command removes
1594 the definition only if it is set in @var{context}.
1595 Properties that have been set in enclosing contexts will
1596 not be altered by an unset in an enclosed context:
1598 @lilypond[quote,verbatim,relative=2]
1599 \set Score.autoBeaming = ##t
1604 \unset Score.autoBeaming
1612 Like @code{\set}, the @var{context} argument does not have to be
1613 specified for a bottom context, so the two statements
1616 \set Voice.autoBeaming = ##t
1617 \set autoBeaming = ##t
1621 are equivalent if the current bottom context is @code{Voice}.
1625 Preceding a @code{\set} command by @code{\once} makes the
1626 setting apply to only a single time-step:
1628 @lilypond[quote,verbatim,relative=2]
1630 \once \set fontSize = #4.7
1635 A full description of all available context properties is in the
1636 internals reference, see
1638 @rinternals{Tunable context properties}.
1641 Translation @expansion{} Tunable context properties.
1646 Internals Reference:
1648 @rinternals{Tunable context properties}.
1651 @cindex grob properties
1652 @cindex properties, grob
1656 @node The override command
1657 @subsection The @code{\override} command
1659 There is a special type of context property: the grob
1660 description. Grob descriptions are named in @code{StudlyCaps}
1661 (starting with capital letters). They contain the
1662 @q{default settings} for a particular kind of grob as an
1663 association list. See @file{scm/define-grobs.scm}
1664 to see the settings for each grob description. Grob descriptions
1665 are modified with @code{\override}.
1667 @code{\override} is actually a shorthand;
1670 \override @var{context}.@var{GrobName} #'@var{property} = #@var{value}
1674 is more or less equivalent to
1676 @c leave this long line -gp
1678 \set @var{context}.@var{GrobName} =
1679 #(cons (cons '@var{property} @var{value})
1680 <previous value of @var{context}.@var{GrobName}>)
1683 The value of @code{context}.@code{GrobName} (the alist) is used to initialize
1684 the properties of individual grobs. Grobs have
1685 properties, named in Scheme style, with
1686 @code{dashed-words}. The values of grob properties change
1687 during the formatting process: formatting basically amounts
1688 to computing properties using callback functions.
1690 For example, we can increase the thickness of a note stem by
1691 overriding the @code{thickness} property of the @code{Stem}
1694 @lilypond[quote,verbatim,relative=2]
1696 \override Voice.Stem #'thickness = #3.0
1700 If no context is specified in an @code{\override}, the bottom
1703 @lilypond[quote,verbatim,relative=2]
1704 { \override Staff.Stem #'thickness = #3.0
1708 \override Stem #'thickness = #0.5
1718 @cindex reverting overrides
1719 @cindex overrides, reverting
1721 The effects of @code{\override} can be undone by @code{\revert}:
1723 @lilypond[quote,verbatim,relative=2]
1725 \override Voice.Stem #'thickness = #3.0
1727 \revert Voice.Stem #'thickness
1731 The effects of @code{\override} and @code{\revert} apply to all
1732 grobs in the affected context from the current time forward:
1734 @lilypond[quote,verbatim,relative=2]
1739 \override Staff.Stem #'thickness = #3.0
1743 \revert Staff.Stem #'thickness
1751 @cindex overriding for only one moment
1753 @code{\once} can be used with @code{\override}
1754 to affect only the current time step:
1756 @lilypond[quote,verbatim,relative=2]
1760 \override Stem #'thickness = #3.0
1764 \once \override Stem #'thickness = #3.0
1773 Commands which change output generally look like
1776 \override Voice.Stem #'thickness = #3.0
1780 To construct this tweak we must determine these bits of information:
1783 @item the context: here @code{Voice}.
1784 @item the layout object: here @code{Stem}.
1785 @item the layout property: here @code{thickness}.
1786 @item a sensible value: here @code{3.0}.
1789 Some tweakable options are called @q{subproperties} and reside inside
1790 properties. To tweak those, use commands in the form
1793 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1796 @cindex internal documentation
1797 @cindex finding graphical objects
1798 @cindex graphical object descriptions
1801 @cindex internal documentation
1803 For many properties, regardless of the data type of the property, setting the
1804 property to false (@code{#f}) will result in turning it off, causing
1805 LilyPond to ignore that property entirely. This is particularly useful for
1806 turning off grob properties which may otherwise be causing problems.
1808 We demonstrate how to glean this information from the notation manual
1809 and the program reference.
1814 Internals Reference:
1815 @rinternals{Backend}
1817 @node The tweak command
1818 @subsection The @code{\tweak} command
1823 Changing grob properties
1824 with @code{\override} causes the changes to apply to all of the
1825 given grobs in the context at the moment the change applies.
1826 Sometimes, however, it is desirable to have changes apply to just
1827 one grob, rather than to all grobs in the affected context. This is
1828 accomplished with the @code{\tweak} command, which has the following
1832 \tweak #'@code{grob-property} #@code{value}
1835 The @code{\tweak} command applies to the object that immediately
1836 follows @code{value} in the music stream.
1839 In some cases, it is possible to take a short-cut for tuning
1840 graphical objects. For objects that are created directly from
1841 an item in the input file, you can use the @code{\tweak} command.
1844 @lilypond[relative=2,verbatim,quote]
1849 \tweak #'duration-log #1
1852 -\tweak #'padding #8
1858 But the main use of the @code{\tweak} command is to modify just
1859 one of a number of notation elements which start at the same musical
1860 moment, like the notes of a chord, or tuplet brackets which start
1863 The @code{\tweak} command sets a property in the following object
1864 directly, without requiring the grob name or context to be
1865 specified. For this to work, it is necessary for the @code{\tweak}
1866 command to remain immediately adjacent to the object to which it is
1867 to apply after the input file has been converted to a music stream.
1868 This is often not the case, as many additional elements are inserted
1869 into the music stream implicitly. For example, when a note which is
1870 not part of a chord is processed, LilyPond implicitly inserts a
1871 @code{ChordEvent} event before the note, so separating the tweak
1872 from the note. However, if chord symbols are placed round the
1873 tweak and the note, the @code{\tweak} command comes after the
1874 @code{ChordEvent} in the music stream, so remaining adjacent to the
1875 note, and able to modify it.
1879 @lilypond[relative=2,verbatim,quote]
1880 <\tweak #'color #red c>4
1886 @lilypond[relative=2,verbatim,quote]
1887 \tweak #'color #red c4
1892 For an introduction to the syntax and uses of the tweak command
1893 see @rlearning{Tweaking methods}.
1895 When several similar items are placed at the same musical moment,
1896 the @code{\override} command cannot be used to modify just one of
1897 them -- this is where the @code{\tweak} command must be used.
1898 Items which may appear more than once at the same musical moment
1899 include the following:
1901 @c TODO expand to include any further uses of \tweak
1903 @item note heads of notes inside a chord
1904 @item articulation signs on a single note
1905 @item ties between notes in a chord
1906 @item tuplet brackets starting at the same time
1909 @c TODO add examples of these
1911 @cindex chord, modifying one note in
1913 In this example, the color of one note head and the type of another
1914 note head are modified within a single chord:
1916 @lilypond[relative=2,verbatim,quote]
1921 \tweak #'duration-log #1
1926 @code{\tweak} can be used to modify slurs:
1928 @lilypond[verbatim,quote,relative=1]
1929 c-\tweak #'thickness #5 ( d e f)
1933 For the @code{\tweak} command to work, it must
1934 remain immediately adjacent to the object to which it is
1935 to apply after the input file has been converted to a music stream.
1936 At times, LilyPond may insert additional items into the music stream
1937 during the parsing process. For example, when a note that is not
1938 explicitly part of a chord will be placed in a chord by LilyPond,
1939 so notes to be modified with @code{\tweak} must be placed inside
1942 @lilypond[relative=2,verbatim,quote]
1943 \tweak #'color #red c4
1944 <\tweak #'color #red c>4
1947 The @code{\tweak} command cannot be used to modify any item
1948 that does not appear explicitly in the input file. In particular
1949 it cannot be used to modify stems,
1950 beams or accidentals directly, since these are generated later by
1951 note heads, rather than by music elements in the input stream.
1952 Nor can @code{\tweak} be used to modify clefs or time
1953 signatures, since these become separated from any preceding
1954 @code{\tweak} command in the input stream by the automatic
1955 insertion of extra elements required to specify the context.
1957 Several @code{\tweak} commands may be placed before a
1958 notational element -- all affect it:
1960 @lilypond[verbatim,quote,relative=1]
1962 -\tweak #'style #'dashed-line
1963 -\tweak #'dash-fraction #0.2
1964 -\tweak #'thickness #3
1965 -\tweak #'color #red
1970 The music stream which is generated from a section of an input file,
1971 including any automatically inserted elements, may be examined,
1972 see @rextend{Displaying music expressions}. This may be helpful in
1973 determining what may be modified by a @code{\tweak} command, or
1974 in determining how to adjust the input to make a @code{\tweak}
1980 @rlearning{Tweaking methods}.
1983 @rextend{Displaying music expressions}.
1988 @cindex tweaks in a variable
1989 The @code{\tweak} command cannot be used inside a variable.
1991 @cindex tweaks in lyrics
1992 The @code{\tweak} commands cannot be used in @code{\lyricmode}.
1994 @cindex tweaking control points
1995 @cindex control points, tweaking
1997 The @code{\tweak} command will apply to only the first of several
1998 generated ties in a chord.
2000 @node set versus override
2001 @subsection @code{\set} vs. @code{\override}
2003 @c TODO -- This section is probably unnecessary now.
2006 We have seen two methods of changing properties: @code{\set} and
2007 @code{\override}. There are actually two different kinds of
2010 @code{fontSize} is a special property: it is equivalent to
2011 entering @code{\override ... #'font-size} for all pertinent
2012 objects. Since this is a common change, the special
2013 property (modified with @code{\set}) was created.
2018 @node Modifying alists
2019 @subsection Modifying alists
2021 Some user-configurable properties are internally represented as
2022 @emph{alists} (association lists), which store pairs of
2023 @emph{keys} and @emph{values}. The structure of an alist is:
2026 '((@var{key1} . @var{value1})
2027 (@var{key2} . @var{value2})
2028 (@var{key3} . @var{value3})
2032 If an alist is a grob property or @code{\paper} variable, its keys
2033 can be modified individually without affecting other keys.
2035 For example, to reduce the space between adjacent staves in a
2036 staff-group, use the @code{staff-staff-spacing} property of the
2037 @code{StaffGrouper} grob. The property is an alist with four
2038 keys: @code{basic-distance}, @code{minimum-distance},
2039 @code{padding}, and @code{stretchability}. The standard settings
2040 for this property are listed in the @qq{Backend} section of the
2041 Internals Reference (see @rinternals{StaffGrouper}):
2044 '((basic-distance . 9)
2045 (minimum-distance . 7)
2047 (stretchability . 5))
2050 One way to bring the staves closer together is by reducing the
2051 value of the @code{basic-distance} key (@code{9}) to match the
2052 value of @code{minimum-distance} (@code{7}). To modify a single
2053 key individually, use a @emph{nested declaration}:
2055 @lilypond[quote,verbatim]
2056 % default space between staves
2058 \new Staff { \clef treble c''1 }
2059 \new Staff { \clef bass c1 }
2062 % reduced space between staves
2063 \new PianoStaff \with {
2064 % this is the nested declaration
2065 \override StaffGrouper #'staff-staff-spacing #'basic-distance = #7
2067 \new Staff { \clef treble c''1 }
2068 \new Staff { \clef bass c1 }
2072 Using a nested declaration will update the specified key (such as
2073 @code{basic-distance} in the above example) without altering any
2074 other keys already set for the same property.
2076 Now suppose we want the staves to be as close as possible without
2077 overlapping. The simplest way to do this is to set all four alist
2078 keys to zero. However, it is not necessary to enter four nested
2079 declarations, one for each key. Instead, the property can be
2080 completely re-defined with one declaration, as an alist:
2082 @lilypond[quote,verbatim]
2083 \new PianoStaff \with {
2084 \override StaffGrouper #'staff-staff-spacing =
2085 #'((basic-distance . 0)
2086 (minimum-distance . 0)
2088 (stretchability . 0))
2090 \new Staff { \clef treble c''1 }
2091 \new Staff { \clef bass c1 }
2095 Note that any keys not explicitly listed in the alist definition
2096 will be reset to their @emph{default-when-unset} values. In the
2097 case of @code{staff-staff-spacing}, any unset key-values would be
2098 reset to zero (except @code{stretchability}, which takes the value
2099 of @code{basic-distance} when unset). Thus the following two
2100 declarations are equivalent:
2103 \override StaffGrouper #'staff-staff-spacing =
2104 #'((basic-distance . 7))
2106 \override StaffGrouper #'staff-staff-spacing =
2107 #'((basic-distance . 7)
2108 (minimum-distance . 0)
2110 (stretchability . 7))
2113 One (possibly unintended) consequence of this is the removal of
2114 any standard settings that are set in an initialization file and
2115 loaded each time an input file is compiled. In the above example,
2116 the standard settings for @code{padding} and
2117 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2118 are reset to their default-when-unset values (zero for both keys).
2119 Defining a property or variable as an alist (of any size) will
2120 always reset all unset key-values to their default-when-unset
2121 values. Unless this is the intended result, it is safer to update
2122 key-values individually with a nested declaration.
2124 @warning{Nested declarations will not work for context property
2125 alists (such as @code{beamExceptions}, @code{keySignature},
2126 @code{timeSignatureSettings}, etc.). These properties can only be
2127 modified by completely re-defining them as alists.}
2130 @node Useful concepts and properties
2131 @section Useful concepts and properties
2136 * Direction and placement::
2137 * Distances and measurements::
2138 * Staff symbol properties::
2140 * Visibility of objects::
2142 * Rotating objects::
2146 @subsection Input modes
2148 The way in which the notation contained within an input file is
2149 interpreted is determined by the current input mode.
2153 This is activated with the @code{\chordmode} command, and causes
2154 input to be interpreted with the syntax of chord notation, see
2155 @ref{Chord notation}. Chords are rendered as notes on a staff.
2157 Chord mode is also activated with the @code{\chords} command.
2158 This also creates a new @code{ChordNames} context and
2159 causes the following input to be interpreted with the syntax of
2160 chord notation and rendered as chord names in the @code{ChordNames}
2161 context, see @ref{Printing chord names}.
2165 This is activated with the @code{\drummode} command, and causes
2166 input to be interpreted with the syntax of drum notation, see
2167 @ref{Basic percussion notation}.
2169 Drum mode is also activated with the @code{\drums} command.
2170 This also creates a new @code{DrumStaff} context and causes the
2171 following input to be interpreted with the syntax of drum notation
2172 and rendered as drum symbols on a drum staff, see @ref{Basic
2173 percussion notation}.
2175 @strong{Figure mode}
2177 This is activated with the @code{\figuremode} command, and causes
2178 input to be interpreted with the syntax of figured bass, see
2179 @ref{Entering figured bass}.
2181 Figure mode is also activated with the @code{\figures} command.
2182 This also creates a new @code{FiguredBass} context and causes the
2183 following input to be interpreted with the figured bass syntax
2184 and rendered as figured bass symbols in the @code{FiguredBass}
2185 context, see @ref{Introduction to figured bass}.
2187 @strong{Fret and tab modes}
2189 There are no special input modes for entering fret and tab symbols.
2191 To create tab diagrams, enter notes or chords in note mode and
2192 render them in a @code{TabStaff} context, see
2193 @ref{Default tablatures}.
2195 To create fret diagrams above a staff, you have two choices.
2196 You can either use the @code{FretBoards} context (see
2197 @ref{Automatic fret diagrams} or you can enter them as a markup
2198 above the notes using the @code{\fret-diagram} command (see
2199 @ref{Fret diagram markups}).
2201 @strong{Lyrics mode}
2203 This is activated with the @code{\lyricmode} command, and causes
2204 input to be interpreted as lyric syllables with optional durations
2205 and associated lyric modifiers, see @ref{Vocal music}.
2207 Lyric mode is also activated with the @code{\addlyrics} command.
2208 This also creates a new @code{Lyrics} context and an implicit
2209 @code{\lyricsto} command which associates the following lyrics
2210 with the preceding music.
2212 @strong{Markup mode}
2214 This is activated with the @code{\markup} command, and causes
2215 input to be interpreted with the syntax of markup, see
2216 @ref{Text markup commands}.
2218 @c silly work-around for texinfo broken-ness
2219 @c (@strong{Note...} causes a spurious cross-reference in Info)
2222 This is the default mode or it may be activated with the
2223 @code{\notemode} command. Input is interpreted as pitches,
2224 durations, markup, etc and typeset as musical notation on a staff.
2226 It is not normally necessary to specify note mode explicitly, but
2227 it may be useful to do so in certain situations, for example if you
2228 are in lyric mode, chord mode or any other mode and want to insert
2229 something that only can be done with note mode syntax.
2231 For example, to indicate dynamic markings for the verses of a
2232 choral pieces it is necessary to enter note mode to interpret
2235 @lilypond[verbatim,relative=2,quote]
2238 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2242 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2249 @node Direction and placement
2250 @subsection Direction and placement
2252 In typesetting music the direction and placement of many items is
2253 a matter of choice. For example, the stems of notes can
2254 be directed up or down; lyrics, dynamics, and other expressive
2255 marks may be placed above or below the staff; text may be aligned
2256 left, right or center; etc. Most of these choices may be left to
2257 be determined automatically by LilyPond, but in some cases it may
2258 be desirable to force a particular direction or placement.
2260 @strong{Articulation direction indicators}
2262 By default some directions are always up or always down (e.g.
2263 dynamics or fermata), while other things can alternate between
2264 up or down based on the stem direction (like slurs or accents).
2266 @c TODO Add table showing these
2268 The default action may be overridden by prefixing the articulation
2269 by a @emph{direction indicator}. Three direction indicators are
2270 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2271 and @code{-} (meaning @qq{use default direction}). The direction
2272 indicator can usually be omitted, in which case @code{-} is assumed,
2273 but a direction indicator is @strong{always} required before
2276 @item @code{\tweak} commands
2277 @item @code{\markup} commands
2278 @item @code{\tag} commands
2279 @item string markups, e.g. -"string"
2280 @item fingering instructions, e.g. @w{@code{-1}}
2281 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2284 Direction indicators affect only the next note:
2286 @lilypond[verbatim,quote,relative=2]
2293 @strong{The direction property}
2295 The position or direction of many layout objects is controlled
2296 by the @code{direction} property.
2298 The value of the @code{direction} property may be
2299 set to @code{1}, meaning @qq{up} or @qq{above}, or to @w{@code{-1}},
2300 meaning @qq{down} or @qq{below}. The symbols @code{UP} and
2301 @code{DOWN} may be used instead of @code{1} and @w{@code{-1}}
2302 respectively. The default direction may be specified by setting
2303 @code{direction} to @code{0} or @code{CENTER}. Alternatively,
2304 in many cases predefined commands
2305 exist to specify the direction. These are all of the form
2308 @code{\xxxUp}, @code{xxxDown}, @code{xxxNeutral}
2311 where @code{xxxNeutral} means @qq{use the default direction}.
2312 See @rlearning{Within-staff objects}.
2314 In a few cases, arpeggio being the only common example, the value
2315 of the @code{direction} property specifies whether the object
2316 is to be placed to the right or left of the parent object. In
2317 this case @w{@code{-1}} or @code{LEFT} means @qq{to the left} and
2318 @code{1} or @code{RIGHT} means @qq{to the right}. @code{0}
2319 or @code{CENTER} means @qq{use the default} direction, as before.
2322 These all have side-axis set to #X
2323 AmbitusAccidental - direction has no effect
2325 StanzaNumber - not tried
2326 TrillPitchAccidental - not tried
2327 TrillPitchGroup - not tried
2330 These indications affect all notes until they are cancelled.
2332 @lilypond[verbatim,quote,relative=2]
2342 @node Distances and measurements
2343 @subsection Distances and measurements
2345 @cindex distances, absolute
2346 @cindex distances, scaled
2353 Distances in LilyPond are of two types: absolute and scaled.
2355 Absolute distances are used for specifying margins, indents, and
2356 other page layout details, and are by default specified in
2357 millimeters. Distances may be specified in other units by
2358 following the quantity by @code{\mm}, @code{\cm},
2359 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2360 an inch). Page layout distances can also be specified in scalable
2361 units (see the following paragraph) by appending
2362 @code{\staff-space} to the quantity. Page layout is described in
2363 detail in @ref{Page layout}.
2365 Scaled distances are always specified in units of the staff-space
2366 or, rarely, the half staff-space. The staff-space is the distance
2367 between two adjacent staff lines. The default value can be changed
2368 globally by setting the global staff size, or it can be overridden
2369 locally by changing the @code{staff-space} property of
2370 @code{StaffSymbol}. Scaled distances automatically scale with any
2371 change to the either the global staff size or the
2372 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2373 automatically only with changes to the global staff size.
2374 The global staff size thus enables the overall size of a rendered
2375 score to be easily varied. For the methods of setting the global
2376 staff size see @ref{Setting the staff size}.
2380 If just a section of a score needs to be rendered to a different
2381 scale, for example an ossia section or a footnote, the global staff
2382 size cannot simply be changed as this would affect the entire score.
2383 In such cases the change in size is made by overriding both the
2384 @code{staff-space} property of @code{StaffSymbol} and the size of
2385 the fonts. A Scheme function, @code{magstep}, is available to
2386 convert from a font size change to the equivalent change in
2387 @code{staff-space}. For an explanation and an example of its use,
2388 see @rlearning{Length and thickness of objects}.
2393 @rlearning{Length and thickness of objects}.
2397 @ref{Setting the staff size}.
2400 @node Staff symbol properties
2401 @subsection Staff symbol properties
2403 @cindex adjusting staff symbol
2404 @cindex drawing staff symbol
2405 @cindex staff symbol, setting of
2407 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2408 @c Need to think of uses for these properties. Eg 'line-positions
2409 @c is used in a snippet to thicken centre line.
2410 @c If retained, add @ref to here in 1.6.2 -td
2412 The vertical position of staff lines and the number of staff lines
2413 can be defined at the same time. As the following example shows,
2414 note positions are not influenced by the staff line positions.
2416 @warning{The @code{'line-positions} property overrides the
2417 @code{'line-count} property. The number of staff lines is
2418 implicitly defined by the number of elements in the list of values
2419 for @code{'line-positions}.}
2421 @lilypond[verbatim,quote,relative=1]
2423 \override StaffSymbol #'line-positions = #'(7 3 0 -4 -6 -7)
2428 The width of a staff can be modified. The units are staff
2429 spaces. The spacing of objects inside the staff is not affected by
2432 @lilypond[verbatim,quote,relative=1]
2434 \override StaffSymbol #'width = #23
2441 @subsection Spanners
2443 Many objects of musical notation extend over several notes or even
2444 several bars. Examples are slurs, beams, tuplet brackets, volta
2445 repeat brackets, crescendi, trills, and glissandi. Such objects
2446 are collectively called @qq{spanners}, and have special properties to control
2447 their appearance and behaviour. Some of these properties are common
2448 to all spanners; others are restricted to a sub-set of the spanners.
2450 All spanners support the @code{spanner-interface}. A few, essentially
2451 those that draw a straight line between the two objects, support in
2452 addition the @code{line-spanner-interface}.
2454 @unnumberedsubsubsec Using the @code{spanner-interface}
2456 This interface provides two properties that apply to several spanners.
2458 @strong{@i{The @code{minimum-length} property}}
2460 The minimum length of the spanner is specified by the
2461 @code{minimum-length} property. Increasing this usually has the
2462 necessary effect of increasing the spacing of the notes between the
2463 two end points. However, this override has no effect on
2464 many spanners, as their length is determined by other considerations.
2465 A few examples where it is effective are shown below.
2475 Works as long as callback is made:
2479 Works not at all for:
2488 @lilypond[verbatim,quote,relative=2]
2491 % increase the length of the tie
2492 -\tweak #'minimum-length #5
2496 @lilypond[verbatim,quote,relative=2]
2498 \compressFullBarRests
2500 % increase the length of the rest bar
2501 \once \override MultiMeasureRest #'minimum-length = #20
2506 @lilypond[verbatim,quote,relative=2]
2508 % increase the length of the hairpin
2509 \override Hairpin #'minimum-length = #20
2513 This override can also be used to increase the length of slurs and
2516 @lilypond[verbatim,quote,relative=2]
2519 -\tweak #'minimum-length #5
2524 -\tweak #'minimum-length #5
2528 For some layout objects, the @code{minimum-length} property becomes
2529 effective only if the @code{set-spacing-rods} procedure is called
2530 explicitly. To do this, the @code{springs-and-rods} property should
2531 be set to @code{ly:spanner::set-spacing-rods}. For example,
2532 the minimum length of a glissando has no effect unless the
2533 @code{springs-and-rods} property is set:
2535 @lilypond[verbatim,quote,relative=1]
2539 % not effective alone
2540 \once \override Glissando #'minimum-length = #20
2543 % effective only when both overrides are present
2544 \once \override Glissando #'minimum-length = #20
2545 \once \override Glissando #'springs-and-rods = #ly:spanner::set-spacing-rods
2549 The same is true of the @code{Beam} object:
2551 @lilypond[verbatim,quote,relative=1]
2552 % not effective alone
2553 \once \override Beam #'minimum-length = #20
2556 % effective only when both overrides are present
2557 \once \override Beam #'minimum-length = #20
2558 \once \override Beam #'springs-and-rods = #ly:spanner::set-spacing-rods
2562 @strong{@i{The @code{to-barline} property}}
2564 The second useful property of the @code{spanner-interface} is
2565 @code{to-barline}. By default this is true, causing hairpins and
2566 other spanners which are terminated on the first note of a measure to
2567 end instead on the immediately preceding bar line. If set to false,
2568 the spanner will extend beyond the bar line and end on the note
2571 @lilypond[verbatim,quote,relative=2]
2572 a \< a a a a \! a a a \break
2573 \override Hairpin #'to-barline = ##f
2574 a \< a a a a \! a a a
2577 This property is not effective for all spanners. For example,
2578 setting it to @code{#t} has no effect on slurs or phrasing slurs
2579 or on other spanners for which terminating on the bar line would
2582 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2584 Objects which support the @code{line-spanner-interface} include
2587 @item @code{DynamicTextSpanner}
2588 @item @code{Glissando}
2589 @item @code{TextSpanner}
2590 @item @code{TrillSpanner}
2591 @item @code{VoiceFollower}
2594 The routine responsible for drawing the stencils for these spanners is
2595 @code{ly:line-interface::print}. This routine determines the
2596 exact location of the two end points and draws a line
2597 between them, in the style requested. The locations of the two
2598 end points of the spanner are computed on-the-fly, but it is
2599 possible to override their Y-coordinates. The
2600 properties which need to be specified are nested
2601 two levels down within the property hierarchy, but the syntax of
2602 the @code{\override} command is quite simple:
2604 @lilypond[relative=2,quote,verbatim]
2606 \once \override Glissando #'(bound-details left Y) = #3
2607 \once \override Glissando #'(bound-details right Y) = #-2
2611 The units for the @code{Y} property are @code{staff-space}s,
2612 with the center line of the staff being the zero point.
2613 For the glissando, this is the value for @code{Y} at the
2614 X-coordinate corresponding to the center point of each note head,
2615 if the line is imagined to be extended to there.
2617 If @code{Y} is not set, the value is computed from the vertical
2618 position of the corresponding attachment point of the spanner.
2620 In case of a line break, the values for the end points are
2621 specified by the @code{left-broken} and @code{right-broken}
2622 sub-lists of @code{bound-details}. For example:
2624 @lilypond[relative=2,ragged-right,verbatim,quote]
2625 \override Glissando #'breakable = ##t
2626 \override Glissando #'(bound-details right-broken Y) = #-3
2627 c1 \glissando \break
2632 A number of further properties of the @code{left} and
2633 @code{right} sub-lists of the @code{bound-details} property
2634 may be modified in the same way as @code{Y}:
2638 This sets the Y-coordinate of the end point, in @code{staff-space}s
2639 offset from the staff center line. By default, it is the center of
2640 the bound object, so a glissando points to the vertical center of
2643 For horizontal spanners, such as text spanners and trill spanners,
2644 it is hardcoded to 0.
2647 This determines where the line starts and ends in the X-direction,
2648 relative to the bound object. So, a value of @w{@code{-1}} (or
2649 @code{LEFT}) makes the line start/end at the left side of the note
2650 head it is attached to.
2653 This is the absolute X-coordinate of the end point. It is usually
2654 computed on the fly, and overriding it has little useful effect.
2657 Line spanners may have symbols at the beginning or end, which is
2658 contained in this sub-property. This is for internal use; it is
2659 recommended that @code{text} be used instead.
2662 This is a markup that is evaluated to yield the stencil. It is used
2663 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
2665 @lilypond[quote,ragged-right,relative=2,verbatim]
2666 \override TextSpanner #'(bound-details left text)
2667 = \markup { \small \bold Slower }
2668 c2\startTextSpan b c a\stopTextSpan
2671 @item stencil-align-dir-y
2672 @item stencil-offset
2673 Without setting one of these, the stencil is simply put at the
2674 end-point, centered on the line, as defined by the @code{X} and
2675 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
2676 or @code{stencil-offset} will move the symbol at the edge vertically
2677 relative to the end point of the line:
2679 @lilypond[relative=1,quote,verbatim]
2680 \override TextSpanner
2681 #'(bound-details left stencil-align-dir-y) = #-2
2682 \override TextSpanner
2683 #'(bound-details right stencil-align-dir-y) = #UP
2685 \override TextSpanner
2686 #'(bound-details left text) = #"ggg"
2687 \override TextSpanner
2688 #'(bound-details right text) = #"hhh"
2689 c4^\startTextSpan c c c \stopTextSpan
2692 Note that negative values move the text @emph{up}, contrary to the
2693 effect that might be expected, as a value of @w{@code{-1}} or
2694 @code{DOWN} means align the @emph{bottom} edge of the text with
2695 the spanner line. A value of @code{1} or @code{UP} aligns
2696 the top edge of the text with the spanner line.
2699 Setting this sub-property to @code{#t} produces an arrowhead at the
2703 This sub-property controls the space between the specified
2704 end point of the line and the actual end. Without padding, a
2705 glissando would start and end in the center of each note head.
2709 The music function @code{\endSpanners} terminates the spanner
2710 which starts on the immediately following note prematurely. It
2711 is terminated after exactly one note, or at the following bar line
2712 if @code{to-barline} is true and a bar line occurs before the next
2715 @lilypond[verbatim,quote,ragged-right,relative=2]
2717 c2 \startTextSpan c2 c2
2722 When using @code{\endSpanners} it is not necessary to close
2723 \startTextSpan with \stopTextSpan, nor is it necessary to close
2724 hairpins with @code{\!}.
2728 Internals Reference:
2729 @rinternals{TextSpanner},
2730 @rinternals{Glissando},
2731 @rinternals{VoiceFollower},
2732 @rinternals{TrillSpanner},
2733 @rinternals{line-spanner-interface}.
2736 @node Visibility of objects
2737 @subsection Visibility of objects
2739 @cindex objects, visibility of
2740 @cindex grobs, visibility of
2741 @cindex visibility of objects
2743 There are four main ways in which the visibility of layout objects
2744 can be controlled: their stencil can be removed, they can be made
2745 transparent, they can be colored white, or their
2746 @code{break-visibility} property can be overridden. The first
2747 three apply to all layout objects; the last to just a few -- the
2748 @emph{breakable} objects. The Learning Manual introduces these
2749 four techniques, see @rlearning{Visibility and color of objects}.
2751 There are also a few other techniques which are specific to
2752 certain layout objects. These are covered under Special
2756 * Removing the stencil::
2757 * Making objects transparent::
2758 * Painting objects white::
2759 * Using break-visibility::
2760 * Special considerations::
2764 @node Removing the stencil
2765 @unnumberedsubsubsec Removing the stencil
2767 @cindex stencil, removing
2769 Every layout object has a stencil property. By default this is set
2770 to the specific function which draws that object. If this property
2771 is overridden to @code{#f} no function will be called and the object
2772 will not be drawn. The default action can be recovered with
2775 @lilypond[quote,verbatim,relative=1]
2777 \override Score.BarLine #'stencil = ##f
2779 \revert Score.BarLine #'stencil
2783 @node Making objects transparent
2784 @unnumberedsubsubsec Making objects transparent
2786 @cindex transparent, making objects
2788 Every layout object has a transparent property which by default is
2789 set to @code{#f}. If set to @code{#t} the object still occupies
2790 space but is made invisible.
2792 @lilypond[quote,verbatim,relative=2]
2794 \once \override NoteHead #'transparent = ##t
2798 @node Painting objects white
2799 @unnumberedsubsubsec Painting objects white
2801 @cindex objects, coloring
2802 @cindex coloring objects
2804 @cindex printing order
2805 @cindex overwriting objects
2806 @cindex objects, overwriting
2807 @cindex grobs, overwriting
2809 Every layout object has a color property which by default is set
2810 to @code{black}. If this is overridden to @code{white} the object
2811 will be indistinguishable from the white background. However,
2812 if the object crosses other objects the color of the crossing
2813 points will be determined by the order in which they are drawn,
2814 and this may leave a ghostly image of the white object, as shown
2817 @lilypond[quote,verbatim,relative=2]
2818 \override Staff.Clef #'color = #white
2822 This may be avoided by changing the order of printing the objects.
2823 All layout objects have a @code{layer} property which should be set
2824 to an integer. Objects with the lowest value of @code{layer} are
2825 drawn first, then objects with progressively higher values are drawn,
2826 so objects with higher values overwrite objects with lower values.
2827 By default most objects are assigned a @code{layer} value of
2828 @code{1}, although a few objects, including @code{StaffSymbol} and
2829 @code{BarLine}, are assigned a value of @code{0}. The order of
2830 printing objects with the same value of @code{layer} is indeterminate.
2832 In the example above the white clef, with a default @code{layer}
2833 value of @code{1}, is drawn after the staff lines (default
2834 @code{layer} value @code{0}), so overwriting them. To change this,
2835 the @code{Clef} object must be given in a lower value of
2836 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
2838 @lilypond[quote,verbatim,relative=2]
2839 \override Staff.Clef #'color = #white
2840 \override Staff.Clef #'layer = #-1
2844 @node Using break-visibility
2845 @unnumberedsubsubsec Using break-visibility
2847 @c TODO Add making other objects breakable
2849 @cindex break-visibility
2851 Most layout objects are printed only once, but some like
2852 bar lines, clefs, time signatures and key signatures, may need
2853 to be printed twice when a line break occurs -- once at the end
2854 of the line and again at the start of the next line. Such
2855 objects are called @emph{breakable}, and have a property, the
2856 @code{break-visibility} property to control their visibility
2857 at the three positions in which they may appear -- at the
2858 start of a line, within a line if they are changed, and at the
2859 end of a line if a change takes place there.
2861 For example, the time signature
2862 by default will be printed at the start of the first line, but
2863 nowhere else unless it changes, when it will be printed at the
2864 point at which the change occurs. If this change occurs at the
2865 end of a line the new time signature will be printed at the start
2866 of the next line and a cautionary time signature will be printed
2867 at the end of the previous line as well.
2869 This behaviour is controlled by the @code{break-visibility}
2870 property, which is explained in
2871 @c Leave this ref on a newline - formats incorrectly otherwise -td
2872 @rlearning{Visibility and color of objects}. This property takes
2873 a vector of three booleans which, in order, determine whether the
2874 object is printed at the end of, within the body of, or at the
2875 beginning of a line. Or to be more precise, before a line break,
2876 where there is no line break, or after a line break.
2878 Alternatively, these eight combinations may be specified
2879 by pre-defined functions, defined in @file{scm/output-lib.scm},
2880 where the last three columns indicate whether the layout objects
2881 will be visible in the positions shown at the head of the columns:
2883 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {yes} {yes} {yes}
2884 @headitem Function @tab Vector @tab Before @tab At no @tab After
2885 @headitem form @tab form @tab break @tab break @tab break
2887 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
2888 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
2889 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
2890 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
2891 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
2892 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
2893 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
2894 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
2897 The default settings of @code{break-visibility} depend on the
2898 layout object. The following table shows all the layout objects
2899 of interest which are affected by @code{break-visibility} and the
2900 default setting of this property:
2902 @multitable @columnfractions .3 .3 .4
2904 @headitem Layout object @tab Usual context @tab Default setting
2906 @c omit Ambitus as it appears not to be affected by break-visibility -td
2907 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
2908 @item @code{BarLine} @tab @code{Score} @tab calculated
2909 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
2910 @c omit the following item until it can be explained -td
2911 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
2912 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2913 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
2914 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
2915 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
2916 @c omit KeyCancellation until it can be explained -td
2917 @c @item @code{KeyCancellation} @tab ?? @tab @code{begin-of-line-invisible}
2918 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
2919 @c omit LeftEdge until it can be explained -td
2920 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
2921 @item @code{OctavateEight} @tab @code{Staff} @tab @code{begin-of-line-visible}
2922 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
2923 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
2927 The example below shows the use of the vector form to control the
2928 visibility of bar lines:
2930 @lilypond[quote,verbatim,relative=1,ragged-right]
2933 % Remove bar line at the end of the current line
2934 \once \override Score.BarLine #'break-visibility = #'#(#f #t #t)
2940 Although all three components of the vector used to override
2941 @code{break-visibility} must be present, not all of them are
2942 effective with every layout object, and some combinations may
2943 even give errors. The following limitations apply:
2946 @item Bar lines cannot be printed at start of line.
2947 @item A bar number cannot be printed at the start of the first
2948 line unless it is set to be different from 1.
2949 @item Clef -- see below
2950 @item Double percent repeats are either all printed or all
2951 suppressed. Use begin-of line-invisible to print and
2952 all-invisible to suppress.
2953 @item Key signature -- see below
2954 @item OctavateEight -- see below
2957 @node Special considerations
2958 @unnumberedsubsubsec Special considerations
2960 @strong{@emph{Visibility following explicit changes}}
2962 @cindex key signature, visibility following explicit change
2963 @cindex explicitKeySignatureVisibility
2964 @cindex clef, visibility following explicit change
2965 @cindex explicitClefVisibility
2967 The @code{break-visibility} property controls the visibility of
2968 key signatures and changes of clef only at the start of lines,
2969 i.e. after a break. It has no effect on the visibility of the
2970 key signature or clef following an explicit key change or an
2971 explicit clef change within or at the end of a line. In the
2972 following example the key signature following the explicit change
2973 to B-flat major is still visible, even though @code{all-invisible}
2976 @lilypond[quote,verbatim,relative=1,ragged-right]
2979 % Try to remove all key signatures
2980 \override Staff.KeySignature #'break-visibility = #all-invisible
2988 The visibility of such explicit key signature and clef changes is
2989 controlled by the @code{explicitKeySignatureVisibility} and
2990 @code{explicitClefVisibility} properties. These are the equivalent
2991 of the @code{break-visibility} property and both take a vector of
2992 three booleans or the predefined functions listed above, exactly like
2993 @code{break-visibility}. Both are properties of the Staff context,
2994 not the layout objects themselves, and so they are set using the
2995 @code{\set} command. Both are set by default to @code{all-visible}.
2996 These properties control only the visibility of key signatures and
2997 clefs resulting from explicit changes and do not affect key
2998 signatures and clefs at the beginning of lines;
2999 @code{break-visibility} must still be overridden in the appropriate
3000 object to remove these.
3002 @lilypond[quote,verbatim,relative=1,ragged-right]
3005 \set Staff.explicitKeySignatureVisibility = #all-invisible
3006 \override Staff.KeySignature #'break-visibility = #all-invisible
3013 @strong{@emph{Visibility of cautionary accidentals}}
3015 To remove the cautionary accidentals printed at an explicit key
3016 change, set the Staff context property @code{printKeyCancellation}
3019 @lilypond[quote,verbatim,relative=1,ragged-right]
3022 \set Staff.explicitKeySignatureVisibility = #all-invisible
3023 \set Staff.printKeyCancellation = ##f
3024 \override Staff.KeySignature #'break-visibility = #all-invisible
3031 With these overrides only the accidentals before the notes remain
3032 to indicate the change of key.
3034 @c TODO Add visibility of cautionary accidentals before notes
3036 @strong{@emph{Automatic bars}}
3038 @cindex automaticBars
3039 @cindex bar lines, suppressing
3041 As a special case, the printing of bar lines can also be turned off
3042 by setting the @code{automaticBars} property in the Score context.
3043 If set to @code{#f}, bar lines will not be printed automatically;
3044 they must be explicitly created with a @code{\bar} command. Unlike
3045 the @code{\cadenzaOn} predefined command, measures are still counted.
3046 Bar generation will resume according to that count if this property
3047 is later set to @code{#t}. When set to @code{#f}, line breaks can
3048 occur only at explicit @code{\bar} commands.
3052 @strong{@emph{Octavated clefs}}
3054 @cindex octavated clefs, visibility of
3055 @cindex visibility of octavated clefs
3056 @cindex clefs, visibility of octavation
3058 The small octavation symbol on octavated clefs is produced by the
3059 @code{OctavateEight} layout object. Its visibility is automatically
3060 inherited from the @code{Clef} object, so it is not necessary to apply
3061 any required @code{break-visibility} overrides to the @code{OctavateEight}
3062 layout objects to suppress octavation symbols for invisible clefs.
3064 For explicit clef changes, the @code{explicitClefVisibility}
3065 property controls both the clef symbol and any octavation symbol
3071 @rlearning{Visibility and color of objects}
3075 @subsection Line styles
3077 Some performance indications, e.g., @i{rallentando} and
3078 @i{accelerando} and @i{trills} are written as text and are
3079 extended over many measures with lines, sometimes dotted or wavy.
3081 These all use the same routines as the glissando for drawing the
3082 texts and the lines, and tuning their behavior is therefore also
3083 done in the same way. It is done with a spanner, and the routine
3084 responsible for drawing the spanners is
3085 @code{ly:line-interface::print}. This routine determines the
3086 exact location of the two @i{span points} and draws a line
3087 between them, in the style requested.
3089 Here is an example showing the different line styles available,
3090 and how to tune them.
3092 @lilypond[relative=2,ragged-right,verbatim,quote]
3094 \once \override Glissando #'style = #'dashed-line
3096 \override Glissando #'style = #'dotted-line
3098 \override Glissando #'style = #'zigzag
3100 \override Glissando #'style = #'trill
3104 The locations of the end-points of the spanner are computed
3105 on-the-fly for every graphic object, but it is possible to
3109 @lilypond[relative=2,ragged-right,verbatim,quote]
3111 \once \override Glissando #'(bound-details right Y) = #-2
3115 The value for @code{Y} is set to @w{@code{-2}} for the right end
3116 point. The left side may be similarly adjusted by specifying
3117 @code{left} instead of @code{right}.
3119 If @code{Y} is not set, the value is computed from the vertical
3120 position of the left and right attachment points of the spanner.
3122 Other adjustments of spanners are possible, for details, see
3125 @node Rotating objects
3126 @subsection Rotating objects
3128 Both layout objects and elements of markup text can be rotated by
3129 any angle about any point, but the method of doing so differs.
3132 * Rotating layout objects::
3136 @node Rotating layout objects
3137 @unnumberedsubsubsec Rotating layout objects
3139 @cindex rotating objects
3140 @cindex objects, rotating
3142 All layout objects which support the @code{grob-interface} can be
3143 rotated by setting their @code{rotation} property. This takes a
3144 list of three items: the angle of rotation counter-clockwise,
3145 and the x and y coordinates of the point relative to the object's
3146 reference point about which the rotation is to be performed. The
3147 angle of rotation is specified in degrees and the coordinates in
3150 The angle of rotation and the coordinates of the rotation point must
3151 be determined by trial and error.
3153 @cindex hairpins, angled
3154 @cindex angled hairpins
3156 There are only a few situations where the rotation of layout
3157 objects is useful; the following example shows one situation where
3160 @lilypond[quote,verbatim,relative=1]
3162 \override Hairpin #'rotation = #'(20 -1 0)
3166 @node Rotating markup
3167 @unnumberedsubsubsec Rotating markup
3169 All markup text can be rotated to lie at any angle by prefixing it
3170 with the @code{\rotate} command. The command takes two arguments:
3171 the angle of rotation in degrees counter-clockwise and the text to
3172 be rotated. The extents of the text are not rotated: they take
3173 their values from the extremes of the x and y coordinates of the
3174 rotated text. In the following example the
3175 @code{outside-staff-priority} property for text is set to @code{#f}
3176 to disable the automatic collision avoidance, which would push some
3177 of the text too high.
3179 @lilypond[quote,verbatim,relative=1]
3180 \override TextScript #'outside-staff-priority = ##f
3181 g4^\markup { \rotate #30 "a G" }
3182 b^\markup { \rotate #30 "a B" }
3183 des^\markup { \rotate #30 "a D-Flat" }
3184 fis^\markup { \rotate #30 "an F-Sharp" }
3187 @node Advanced tweaks
3188 @section Advanced tweaks
3190 This section discusses various approaches to fine tuning the
3191 appearance of the printed score.
3194 * Aligning objects::
3195 * Vertical grouping of grobs::
3196 * Modifying stencils::
3197 * Modifying shapes::
3203 @rlearning{Tweaking output},
3204 @rlearning{Other sources of information}.
3207 @ref{Explaining the Internals Reference},
3208 @ref{Modifying properties}.
3211 @file{scm/define-grobs.scm}.
3214 @rlsr{Tweaks and overrides}.
3217 @rextend{Interfaces for programmers}.
3219 Internals Reference:
3220 @rinternals{All layout objects}.
3223 @node Aligning objects
3224 @subsection Aligning objects
3226 Graphical objects which support the @code{self-alignment-interface}
3227 and/or the @code{side-position-interface} can be aligned to a previously
3228 placed object in a variety of ways. For a list of these objects, see
3229 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3231 All graphical objects have a reference point, a horizontal extent and a
3232 vertical extent. The horizontal extent is a pair of numbers
3233 giving the displacements from the reference point of the left and
3234 right edges, displacements to the left being negative. The vertical
3235 extent is a pair of numbers giving the displacement from the reference
3236 point to the bottom and top edges, displacements down being negative.
3238 An object's position on a staff is given by the values of the
3239 @code{X-offset} and @code{Y-offset} properties. The value of
3240 @code{X-offset} gives the displacement from the X coordinate of
3241 the reference point of the parent object, and the value of
3242 @code{Y-offset} gives the displacement from the center line of the
3243 staff. The values of @code{X-offset} and @code{Y-offset} may
3244 be set directly or may be set to be calculated by procedures in order
3245 to achieve alignment with the parent object.
3247 @warning{Many objects have special positioning considerations which
3248 cause any setting of @code{X-offset} or @code{Y-offset} to be
3249 ignored or modified, even though the object supports the
3250 @code{self-alignment-interface}. Overriding the @code{X-offset}
3251 or @code{Y-offset} properties to a fixed value causes the respective
3252 @code{self-alignment} property to be disregarded.}
3254 For example, an accidental can be repositioned vertically by setting
3255 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3257 Rehearsal marks may be aligned with breakable objects such as bar
3258 lines, clef symbols, time signature symbols and key signatures. There
3259 are special properties to be found in the @code{break-aligned-interface}
3260 for positioning rehearsal marks on such objects.
3263 @ref{Using the break-alignable-interface},
3264 @rextend{Callback functions}.
3267 * Setting X-offset and Y-offset directly::
3268 * Using the side-position-interface::
3269 * Using the self-alignment-interface::
3270 * Using the break-alignable-interface::
3273 @node Setting X-offset and Y-offset directly
3274 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3276 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3277 properties of many objects. The following example shows three
3278 notes with the default fingering position and the positions with @code{X-offset}
3279 and @code{Y-offset} modified.
3281 @lilypond[verbatim,quote,relative=2]
3284 -\tweak #'X-offset #0
3285 -\tweak #'Y-offset #0
3288 -\tweak #'X-offset #-1
3289 -\tweak #'Y-offset #1
3295 @node Using the side-position-interface
3296 @unnumberedsubsubsec Using the @code{side-position-interface}
3298 An object which supports the @code{side-position-interface} can be
3299 placed next to its parent object so that
3300 the specified edges of the two objects touch. The object may be
3301 placed above, below, to the right or to the left of the parent.
3302 The parent cannot be specified; it is determined by the order of
3303 elements in the input stream. Most objects have the associated
3304 note head as their parent.
3306 The values of the @code{side-axis} and @code{direction} properties
3307 determine where the object is to be placed, as follows:
3309 @c TODO add an example of each to the table
3311 @multitable @columnfractions .3 .3 .3
3312 @headitem @code{side-axis} @tab @code{direction} @tab
3313 @headitem property @tab property @tab Placement
3315 @item @code{0} @tab @code{-1} @tab left
3316 @item @code{0} @tab @code{1} @tab right
3317 @item @code{1} @tab @code{-1} @tab below
3318 @item @code{1} @tab @code{1} @tab above
3322 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3323 the procedure @code{ly:side-position-interface::x-aligned-side}.
3324 This procedure will return the correct value of @code{X-offset} to
3325 place the object to the left or right side of the parent according
3326 to value of @code{direction}.
3328 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3329 the procedure @code{ly:side-position-interface::y-aligned-side}.
3330 This procedure will return the correct value of @code{Y-offset} to
3331 place the object to the top or bottom of the parent according
3332 to value of @code{direction}.
3334 @c TODO Add examples
3336 @node Using the self-alignment-interface
3337 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3339 @emph{Self-aligning objects horizontally}
3341 The horizontal alignment of an object which supports the
3342 @code{self-alignment-interface} is controlled by the value of
3343 the @code{self-alignment-X} property, provided the object's
3344 @code{X-offset} property is set to
3345 @code{ly:self-alignment-interface::x-aligned-on-self}.
3346 @code{self-alignment-X} may be given any
3347 real value, in units of half the total X extent of the
3348 object. Negative values move the object to the right, positive
3349 to the left. A value of @code{0} centers the object on the
3350 reference point of its parent, a value of @w{@code{-1}} aligns the
3351 left edge of the object on the reference point of its parent,
3352 and a value of @code{1} aligns the right edge of the object on the
3353 reference point of its parent. The symbols @code{LEFT},
3354 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3355 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3357 Normally the @code{\override} command would be used to modify the
3358 value of @code{self-alignment-X}, but the @code{\tweak} command
3359 can be used to separately align several annotations on a single
3362 @lilypond[quote,verbatim,relative=1]
3364 -\tweak #'self-alignment-X #-1
3366 -\tweak #'self-alignment-X #0
3368 -\tweak #'self-alignment-X #RIGHT
3370 -\tweak #'self-alignment-X #-2.5
3371 ^"aligned further to the right"
3374 @emph{Self-aligning objects vertically}
3376 Objects may be aligned vertically in an analogous way to aligning
3377 them horizontally if the @code{Y-offset} property is set to
3378 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3379 other mechanisms are often involved in vertical alignment: the
3380 value of @code{Y-offset} is just one variable taken into account.
3381 This may make adjusting the value of some objects tricky.
3382 The units are just half the vertical extent of the object, which
3383 is usually quite small, so quite large numbers may be required.
3384 A value of @w{@code{-1}} aligns the lower edge of the object with
3385 the reference point of the parent object, a value of @code{0}
3386 aligns the center of the object with the reference point of the
3387 parent, and a value of @code{1} aligns the top edge of the object
3388 with the reference point of the parent. The symbols @code{DOWN},
3389 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3390 @code{0}, and @code{1}, respectively.
3392 @emph{Self-aligning objects in both directions}
3394 By setting both @code{X-offset} and @code{Y-offset}, an object may
3395 be aligned in both directions simultaneously.
3397 The following example shows how to adjust a fingering mark so
3398 that it nestles close to the note head.
3400 @lilypond[quote,verbatim,relative=2]
3402 -\tweak #'self-alignment-X #0.5 % move horizontally left
3403 -\tweak #'Y-offset #ly:self-alignment-interface::y-aligned-on-self
3404 -\tweak #'self-alignment-Y #-1 % move vertically up
3409 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3411 @c Cannot document as they do not seem to operate consistently on all objects -td
3412 @c TODO investigate further
3414 The @code{aligned-on-parent} procedures are used in the same way
3415 as the @code{aligned-on-self} procedures, they difference being
3416 that they permit an object to be aligned with the @emph{edges} of
3417 the parent rather than the parent's reference point. The following
3418 example shows the difference:
3422 @lilypond[verbatim,quote]
3428 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3430 @c Cannot document as they do not seem to operate consistently on all objects -td
3431 @c TODO investigate further
3435 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3437 @node Using the break-alignable-interface
3438 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3440 @cindex align to objects
3441 @cindex break-align-symbols
3443 Rehearsal marks and bar numbers may be aligned with notation
3444 objects other than bar lines. These objects include @code{ambitus},
3445 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3446 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3447 @code{time-signature}.
3449 By default, rehearsal marks and bar numbers will be horizontally
3450 centered above the object:
3452 @lilypond[verbatim,quote,relative=1]
3453 % The rehearsal mark will be centered above the Clef
3454 \override Score.RehearsalMark #'break-align-symbols = #'(clef)
3459 % The rehearsal mark will be centered above the Time Signature
3460 \override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
3466 % The rehearsal mark will be centered above the Breath Mark
3467 \override Score.RehearsalMark #'break-align-symbols = #'(breathing-sign)
3476 A list of possible target alignment objects may be specified. If
3477 some of the objects are invisible at that point due to the setting
3478 of @code{break-visibility} or the explicit visibility settings for
3479 keys and clefs, the rehearsal mark or bar number is aligned to the
3480 first object in the list which is visible. If no objects in the
3481 list are visible the object is aligned to the bar line. If the bar
3482 line is invisible the object is aligned to the place where the bar
3485 @lilypond[verbatim,quote,relative=1]
3486 % The rehearsal mark will be centered above the Key Signature
3487 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3492 % The rehearsal mark will be centered above the Clef
3493 \set Staff.explicitKeySignatureVisibility = #all-invisible
3494 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3499 % The rehearsal mark will be centered above the Bar Line
3500 \set Staff.explicitKeySignatureVisibility = #all-invisible
3501 \set Staff.explicitClefVisibility = #all-invisible
3502 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3509 The alignment of the rehearsal mark relative to the notation object
3510 can be changed, as shown in the following example. In a score with
3511 multiple staves, this setting should be done for all the staves.
3513 @lilypond[verbatim,quote,relative=1]
3514 % The RehearsalMark will be centered above the Key Signature
3515 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3521 % The RehearsalMark will be aligned with the left edge of the Key Signature
3522 \once \override Score.KeySignature #'break-align-anchor-alignment = #LEFT
3526 % The RehearsalMark will be aligned with the right edge of the Key Signature
3527 \once \override Score.KeySignature #'break-align-anchor-alignment = #RIGHT
3533 The rehearsal mark can also be offset to the right or left of the left
3534 edge by an arbitrary amount. The units are staff-spaces:
3536 @lilypond[verbatim,quote,relative=1]
3537 % The RehearsalMark will be aligned with the left edge of the Key Signature
3538 % and then shifted right by 3.5 staff-spaces
3539 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3540 \once \override Score.KeySignature #'break-align-anchor = #3.5
3544 % The RehearsalMark will be aligned with the left edge of the Key Signature
3545 % and then shifted left by 2 staff-spaces
3546 \once \override Score.KeySignature #'break-align-anchor = #-2
3553 @node Vertical grouping of grobs
3554 @subsection Vertical grouping of grobs
3556 @c TODO Expand this section
3558 The VerticalAlignment and VerticalAxisGroup grobs work together.
3559 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3560 etc. VerticalAlignment then vertically aligns the different grobs
3561 grouped together by VerticalAxisGroup. There is usually only one
3562 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3566 @node Modifying stencils
3567 @subsection Modifying stencils
3569 All layout objects have a @code{stencil} property which is part of
3570 the @code{grob-interface}. By default, this property is usually
3571 set to a function specific to the object that is tailor-made to
3572 render the symbol which represents it in the output. For example,
3573 the standard setting for the @code{stencil} property of the
3574 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3576 The standard symbol for any object can be replaced by modifying the
3577 @code{stencil} property to reference a different, specially-written,
3578 procedure. This requires a high level of knowledge of the internal
3579 workings of LilyPond, but there is an easier way which can often
3580 produce adequate results.
3582 This is to set the @code{stencil} property to the procedure which
3583 prints text -- @code{ly:text-interface::print} -- and to add a
3584 @code{text} property to the object which is set to contain the
3585 markup text which produces the required symbol. Due to the
3586 flexibility of markup, much can be achieved -- see in particular
3587 @ref{Graphic notation inside markup}.
3589 The following example demonstrates this by changing the note head
3590 symbol to a cross within a circle.
3592 @lilypond[verbatim,quote]
3594 \once \override NoteHead #'stencil = #ly:text-interface::print
3595 \once \override NoteHead #'text = \markup {
3597 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3598 \musicglyph #"noteheads.s2cross"
3606 Any of the glyphs in the feta Font can be supplied to the
3607 @code{\musicglyph} markup command -- see @ref{The Feta font}.
3609 @c TODO Add inserting eps files or ref to later
3611 @c TODO Add inserting Postscript or ref to later
3616 @ref{Graphic notation inside markup},
3617 @ref{Formatting text},
3618 @ref{Text markup commands},
3619 @ref{The Feta font}.
3622 @node Modifying shapes
3623 @subsection Modifying shapes
3626 * Modifying ties and slurs::
3629 @node Modifying ties and slurs
3630 @unnumberedsubsubsec Modifying ties and slurs
3632 @cindex slurs, modifying
3633 @cindex ties, modifying
3634 @cindex Bézier curves, control points
3635 @cindex control points, Bézier curves
3637 Ties, slurs and phrasing slurs are drawn as third-order Bézier
3638 curves. If the shape of the tie or slur which is calculated
3639 automatically is not optimum, the shape may be modified manually by
3640 explicitly specifying the four control points required to define
3641 a third-order Bézier curve.
3643 Third-order or cubic Bézier curves are defined by four control
3644 points. The first and fourth control points are precisely the
3645 starting and ending points of the curve. The intermediate two
3646 control points define the shape. Animations showing how the curve
3647 is drawn can be found on the web, but the following description
3648 may be helpful. The curve starts from the first control point
3649 heading directly towards the second, gradually bending over to
3650 head towards the third and continuing to bend over to head towards
3651 the fourth, arriving there travelling directly from the third
3652 control point. The curve is entirely contained in the
3653 quadrilateral defined by the four control points.
3655 Here is an example of a case where the tie is not optimum, and
3656 where @code{\tieDown} would not help.
3658 @lilypond[verbatim,quote,relative=1]
3662 { r4 <g c,> <g c,> <g c,> }
3666 One way of improving this tie is to manually modify its control
3669 The coordinates of the Bézier control points are specified in units
3670 of staff-spaces. The X@tie{}coordinate is relative to the reference
3671 point of the note to which the tie or slur is attached, and the
3672 Y@tie{}coordinate is relative to the staff center line. The
3673 coordinates are entered as a list of four pairs of decimal numbers
3674 (reals). One approach is to estimate the coordinates of the two
3675 end points, and then guess the two intermediate points. The optimum
3676 values are then found by trial and error.
3678 It is useful to remember that a symmetric curve requires symmetric
3679 control points, and that Bézier curves have the useful property that
3680 transformations of the curve such as translation, rotation and
3681 scaling can be achieved by applying the same transformation to the
3682 curve's control points.
3684 For the example above the following override gives a satisfactory
3685 tie. Note the placement -- it has to be immediately before the note
3686 to which the start of the tie (or slur) is attached.
3688 @lilypond[verbatim,quote,relative=1]
3692 #'control-points = #'((1 . -1) (3 . 0.6) (12.5 . 0.6) (14.5 . -1))
3696 { r4 <g c,> <g c,> <g c,> }
3701 It is not possible to modify shapes of ties or slurs by changing
3702 the @code{control-points} property if there are multiple ties or slurs
3703 at the same musical moment -- the @code{\tweak} command will also not
3704 work in this case. However, the @code{tie-configuration} property of
3705 @code{TieColumn} can be overridden to set start line and direction as
3709 Internals Reference:
3710 @rinternals{TieColumn}.
3713 @node Using music functions
3714 @section Using music functions
3716 @c TODO -- add @seealso, etc. to these subsections
3718 Where tweaks need to be reused with different music expressions,
3719 it is often convenient to make the tweak part of a @emph{music
3720 function}. In this section, we discuss only @emph{substitution}
3721 functions, where the object is to substitute a variable into a
3722 piece of LilyPond input code. Other more complex functions are
3723 described in @rextend{Music functions}.
3726 * Substitution function syntax::
3727 * Substitution function examples::
3730 @node Substitution function syntax
3731 @subsection Substitution function syntax
3733 Making a function that substitutes a variable into LilyPond
3734 code is easy. The general form of these functions is
3738 #(define-music-function
3739 (parser location @var{arg1} @var{arg2} @dots{})
3740 (@var{type1?} @var{type2?} @dots{})
3742 @var{@dots{}music@dots{}}
3749 @multitable @columnfractions .33 .66
3750 @item @code{@var{argN}}
3751 @tab @var{n}th argument
3753 @item @code{@var{typeN?}}
3754 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
3755 must return @code{#t}.
3757 @item @code{@var{@dots{}music@dots{}}}
3758 @tab normal LilyPond input, using @code{$} to reference arguments
3763 The @code{parser} and @code{location} arguments are mandatory, and
3764 are used in some advanced situations as described in the
3765 @q{Extending} manual (see @rextend{Music functions}). For
3766 substitution functions, just be sure to include them.
3768 The list of type predicates is also required. Some of the most
3769 common type predicates used in music functions are:
3773 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
3783 For a list of available type predicates, see
3784 @ref{Predefined type predicates}. User-defined type predicates
3791 @ref{Predefined type predicates}.
3794 @rextend{Music functions}.
3797 @file{lily/music-scheme.cc},
3799 @file{scm/lily.scm}.
3802 @node Substitution function examples
3803 @subsection Substitution function examples
3805 This section introduces some substitution function examples.
3806 These are not intended to be exhaustive, but rather to demonstrate
3807 some of the possibilities of simple substitution functions.
3809 In the first example, a function is defined that simplifies
3810 setting the padding of a TextScript:
3812 @lilypond[quote,verbatim,ragged-right]
3814 #(define-music-function
3815 (parser location padding)
3818 \once \override TextScript #'padding = $padding
3822 c4^"piu mosso" b a b
3824 c4^"piu mosso" d e f
3826 c4^"piu mosso" fis a g
3830 In addition to numbers, we can use music expressions such
3831 as notes for arguments to music functions:
3833 @c TODO: use a better example (the music argument is redundant).
3835 @lilypond[quote,verbatim,ragged-right]
3837 #(define-music-function
3838 (parser location note)
3841 \once \override Voice.NoteHead #'stencil =
3842 #ly:text-interface::print
3843 \once \override Voice.NoteHead #'text =
3844 \markup \musicglyph #"custodes.mensural.u0"
3845 \once \override Voice.Stem #'stencil = ##f
3849 \relative c' { c4 d e f \custosNote g }
3852 Substitution functions with multiple arguments can be defined:
3854 @lilypond[quote,verbatim,ragged-right]
3856 #(define-music-function
3857 (parser location padding tempotext)
3860 \once \override Score.MetronomeMark #'padding = $padding
3861 \tempo \markup { \bold $tempotext }
3865 \tempo \markup { "Low tempo" }
3867 \tempoPadded #4.0 #"High tempo"
3872 @c TODO: add appropriate @@ref's here.