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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/@/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::
62 * Creating and referencing contexts::
63 * Keeping contexts alive::
64 * Modifying context plug-ins::
65 * Changing context default settings::
66 * Defining new contexts::
67 * Context layout order::
72 @rlearning{Contexts and engravers}.
75 @file{ly/engraver-init.ly},
76 @file{ly/performer-init.ly}.
79 @rlsr{Contexts and engravers}.
82 @rinternals{Contexts},
83 @rinternals{Engravers and Performers}.
86 @node Contexts explained
87 @subsection Contexts explained
90 @c TODO Rethink and rewrite
92 >> > > - list of contexts: my *danger unmaintainable*
93 >> > > alarm just went off. I'm
95 I knew it would... And leaving out some of them is perfectly fine
97 I do think that a list like this, with the main contexts and a
99 description of what they do (perhaps also with a note about what
101 behavior is associated with each of them, but this may be
103 should be there, and then we could simply list the remaining ones
105 further explanation and with links to the IR.
108 @c TODO Improve layout, order and consistency of wording -td
110 @c TODO Add introduction which explains contexts in generality -td
112 @c TODO Describe propagation of property values -td
114 Contexts are arranged hierarchically:
117 * Score - the master of all contexts::
118 * Top-level contexts - staff containers::
119 * Intermediate-level contexts - staves::
120 * Bottom-level contexts - voices::
123 @node Score - the master of all contexts
124 @unnumberedsubsubsec Score - the master of all contexts
126 This is the top level notation context. No other context can
127 contain a Score context. By default the Score context handles
128 the administration of time signatures and makes sure that items
129 such as clefs, time signatures, and key-signatures are aligned
132 A Score context is instantiated implicitly when a
133 @code{\score @{@dots{}@}} or @code{\layout @{@dots{}@}} block is
136 @node Top-level contexts - staff containers
137 @unnumberedsubsubsec Top-level contexts - staff containers
139 @strong{@emph{StaffGroup}}
141 Groups staves while adding a bracket on the left side, grouping
142 the staves together. The bar lines of the contained staves are
143 connected vertically. @code{StaffGroup} only consists of a collection
144 of staves, with a bracket in front and spanning bar lines.
146 @strong{@emph{ChoirStaff}}
148 Identical to @code{StaffGroup} except that the bar lines of the
149 contained staves are not connected vertically.
151 @strong{@emph{GrandStaff}}
153 A group of staves, with a brace on the left side, grouping the
154 staves together. The bar lines of the contained staves are
155 connected vertically.
157 @strong{@emph{PianoStaff}}
159 Just like @code{GrandStaff}, but with support for instrument names
160 to the left of each system.
162 @node Intermediate-level contexts - staves
163 @unnumberedsubsubsec Intermediate-level contexts - staves
165 @strong{@emph{Staff}}
167 Handles clefs, bar lines, keys, accidentals. It can contain
168 @code{Voice} contexts.
170 @strong{@emph{RhythmicStaff}}
172 Like @code{Staff} but for printing rhythms. Pitches are ignored;
173 the notes are printed on one line.
175 @strong{@emph{TabStaff}}
177 Context for generating tablature. By default lays the music
178 expression out as a guitar tablature, printed on six lines.
180 @strong{@emph{DrumStaff}}
182 Handles typesetting for percussion. Can contain @code{DrumVoice}
184 @strong{@emph{VaticanaStaff}}
186 Same as @code{Staff}, except that it is designed for typesetting
187 a piece in gregorian style.
189 @strong{@emph{MensuralStaff}}
191 Same as @code{Staff}, except that it is designed for typesetting
192 a piece in mensural style.
194 @node Bottom-level contexts - voices
195 @unnumberedsubsubsec Bottom-level contexts - voices
197 Voice-level contexts initialise certain properties and start
198 appropriate engravers. A bottom-level context is one without
199 @code{defaultchild}. While it is possible to let it
200 accept/@/contain subcontexts, they can only be created and entered
203 @strong{@emph{Voice}}
205 Corresponds to a voice on a staff. This context handles the
206 conversion of dynamic signs, stems, beams, super- and sub-scripts,
207 slurs, ties, and rests. You have to instantiate this explicitly
208 if you require multiple voices on the same staff.
210 @strong{@emph{VaticanaVoice}}
212 Same as @code{Voice}, except that it is designed for typesetting
213 a piece in gregorian style.
215 @strong{@emph{MensuralVoice}}
217 Same as @code{Voice}, with modifications for typesetting a piece in
220 @strong{@emph{Lyrics}}
222 Corresponds to a voice with lyrics. Handles the printing of a
223 single line of lyrics.
225 @strong{@emph{DrumVoice}}
227 The voice context used in a percussion staff.
229 @strong{@emph{FiguredBass}}
231 The context in which @code{BassFigure} objects are created from
232 input entered in @code{\figuremode} mode.
234 @strong{@emph{TabVoice}}
236 The voice context used within a @code{TabStaff} context. Usually
237 left to be created implicitly.
239 @strong{@emph{CueVoice}}
241 A voice context used to render notes of a reduced size, intended
242 primarily for adding cue notes to a staff, see @ref{Formatting
243 cue notes}. Usually left to be created implicitly.
245 @strong{@emph{ChordNames}}
247 Typesets chord names.
252 Then the following, which I don't know what to do with:
254 * GregorianTranscriptionVoice
255 * GregorianTranscriptionStaff
258 Engraves fretboards from chords. Not easy... Not
260 There is now some documentation on FretBoards in the NR, under
261 instrument-specific notation -- cds.
266 Hard coded entry point for LilyPond. Cannot be tuned.
268 Silently discards all musical information given to this
273 @node Creating and referencing contexts
274 @subsection Creating and referencing contexts
279 @cindex referencing contexts
280 @cindex Contexts, creating and referencing
282 LilyPond will create lower-level contexts automatically if a music
283 expression is encountered before a suitable context exists, but this
284 is usually successful only for simple scores or music fragments like
285 the ones in the documentation. For more complex scores it is
286 advisable to specify all contexts explicitly with either the
287 @code{\new} or @code{\context} command. The syntax of
288 these two commands is very similar:
291 [\new | \context] @var{Context} [ = @var{name}] [@var{music-expression}]
295 where either @code{\new} or @code{\context} may be specified.
296 @var{Context} is the type of context which is to be created,
297 @var{name} is an optional name to be given to the particular context
298 being created and @var{music-expression} is a single music expression
299 that is to be interpreted by the engravers and performers in this
302 The @code{\new} prefix without a name is commonly used to create
303 scores with many staves:
305 @lilypond[quote,verbatim,relative=2]
308 % leave the Voice context to be created implicitly
318 and to place several voices into one staff:
320 @lilypond[quote,verbatim,relative=2]
336 @code{\new} should always be used to specify unnamed contexts.
338 The difference between @code{\new} and @code{\context} is in the
343 @code{\new} with or without a name will always create a fresh,
344 distinct, context, even if one with the same name already exists:
346 @lilypond[quote,verbatim,relative=2]
362 @code{\context} with a name specified will create a distinct context
363 only if a context of the same type with the same name in the same
364 context hierarchy does not already exist. Otherwise it will be taken
365 as a reference to that previously created context, and its music
366 expression will be passed to that context for interpretation.
368 One application of named contexts is in separating the score layout
369 from the musical content. Either of these two forms is valid:
371 @lilypond[quote,verbatim]
385 \context Voice = "one" {
390 \context Voice = "two" {
399 @lilypond[quote,verbatim]
404 \context Voice = "one" {
407 \context Voice = "two" {
413 \context Voice = "one" {
418 \context Voice = "two" {
428 Alternatively, variables may be employed to similar effect. See
429 @rlearning{Organizing pieces with variables}.
432 @code{\context} with no name will match the first of any previously
433 created contexts of the same type in the same context heirarchy,
434 even one that has been given a name, and its music expression will be
435 passed to that context for interpretation. This form is rarely
436 useful. However, @code{\context} with no name and no music expression
437 is used to set the context in which a Scheme procedure specified with
438 @code{\applyContext} is executed:
441 \new Staff \relative c' @{
444 \applyContext #(lambda (ctx)
446 (display (ly:context-current-moment ctx)))
453 A context must be named if it is to be referenced later, for example
454 when lyrics are associated with music:
457 \new Voice = "tenor" @var{music}
459 \new Lyrics \lyricsto "tenor" @var{lyrics}
463 For details of associating lyrics with music see
464 @ref{Automatic syllable durations}.
466 The properties of all contexts of a particular type can be modified
467 in a @code{\layout} block (with a different syntax), see
468 @ref{Changing all contexts of the same type}. This construct also
469 provides a means of keeping layout instructions separate from the
470 musical content. If a single context is to be modified, a @code{\with}
471 block must be used, see @ref{Changing just one specific context}.
475 @rlearning{Organizing pieces with variables}.
478 @ref{Changing just one specific context},
479 @ref{Automatic syllable durations}.
482 @node Keeping contexts alive
483 @subsection Keeping contexts alive
485 @cindex contexts, keeping alive
486 @cindex contexts, lifetime
488 Contexts are usually terminated at the first musical moment in
489 which they have nothing to do. So @code{Voice} contexts die as
490 soon as they contain no events; @code{Staff} contexts die as soon
491 as all the @code{Voice} contexts within them contain no events; etc.
492 This can cause difficulties if earlier contexts which have died
493 have to be referenced, for example, when changing staves with
494 @code{\change} commands, associating lyrics with a voice with
495 @code{\lyricsto} commands, or when adding further musical events to
498 There is an exception to this general rule: just one of the
499 @code{Voice} contexts in a @code{Staff} context or in a
500 @code{<<@dots{}>>} construct will always persist to the end of the
501 enclosing @code{Staff} context or @code{<<@dots{}>>} construct, even
502 though there may be periods when it has nothing to do. The context
503 to persist in this way will be the first one encountered in the
504 first enclosed @code{@{@dots{}@}} construct, ignoring any in enclosed
505 @code{<<@dots{}>>} constructs.
507 Any context can be kept alive by ensuring it has something to do at
508 every musical moment. @code{Staff} contexts are kept alive by
509 ensuring one of their voices is kept alive. One way of doing this
510 is to add spacer rests to a voice in parallel with the real music.
511 These need to be added to every @code{Voice} context which needs to
512 be kept alive. If several voices are to be used sporadically it is
513 safest to keep them all alive rather than attempting to rely on the
514 exceptions mentioned above.
516 In the following example, both voice A and voice B are kept alive
517 in this way for the duration of the piece:
519 @lilypond[quote,verbatim]
520 musicA = \relative c'' { d4 d d d }
521 musicB = \relative c'' { g4 g g g }
524 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
525 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
530 \context Voice = "A" {
534 \context Voice = "B" {
538 \context Voice = "A" { \musicA }
539 \context Voice = "B" { \musicB }
540 \context Voice = "A" { \musicA }
551 @cindex lyrics, aligning with sporadic melody
553 The following example shows how a sporadic melody line with lyrics
554 might be written using this approach. In a real situation the
555 melody and accompaniment would consist of several different
558 @lilypond[quote,verbatim]
559 melody = \relative c'' { a4 a a a }
560 accompaniment = \relative c' { d4 d d d }
561 words = \lyricmode { These words fol -- low the mel -- o -- dy }
564 \new Staff = "music" {
566 \new Voice = "melody" {
568 s1*4 % Keep Voice "melody" alive for 4 bars
571 \new Voice = "accompaniment" {
576 \context Voice = "melody" { \melody }
577 \context Voice = "accompaniment" { \accompaniment }
579 \context Voice = "accompaniment" { \accompaniment }
581 \context Voice = "melody" { \melody }
582 \context Voice = "accompaniment" { \accompaniment }
587 \new Lyrics \with { alignAboveContext = #"music" }
588 \lyricsto "melody" { \words }
593 An alternative way, which may be better in many circumstances, is
594 to keep the melody line alive by simply including spacer notes to
595 line it up correctly with the accompaniment:
597 @lilypond[quote,verbatim]
598 melody = \relative c'' {
604 accompaniment = \relative c' {
610 words = \lyricmode { These words fol -- low the mel -- o -- dy }
614 \new Staff = "music" {
616 \new Voice = "melody" {
620 \new Voice = "accompaniment" {
626 \new Lyrics \with { alignAboveContext = #"music" }
627 \lyricsto "melody" { \words }
633 @node Modifying context plug-ins
634 @subsection Modifying context plug-ins
636 @c TODO Should this be Modifying engravers or Modifying contexts?
638 Notation contexts (like @code{Score} and @code{Staff}) not only store
639 properties, they also contain plug-ins called @q{engravers} that create
640 notation elements. For example, the @code{Voice} context contains a
641 @code{Note_heads_engraver} and the @code{Staff} context contains a
644 For a full a description of each plug-in, see
646 @rinternals{Engravers and Performers}.
649 Internals Reference @expansion{} Translation @expansion{} Engravers.
651 Every context described in
653 @rinternals{Contexts}
656 Internals Reference @expansion{} Translation @expansion{} Context.
658 lists the engravers used for that context.
661 It can be useful to shuffle around these plug-ins. This is done by
662 starting a new context with @code{\new} or @code{\context}, and
668 \new @var{context} \with @{
676 @emph{@dots{}music@dots{}}
681 where the @dots{} should be the name of an engraver. Here is a simple
682 example which removes @code{Time_signature_engraver} and
683 @code{Clef_engraver} from a @code{Staff} context,
685 @lilypond[quote,relative=1,verbatim]
691 \remove "Time_signature_engraver"
692 \remove "Clef_engraver"
699 In the second staff there are no time signature or clef symbols. This
700 is a rather crude method of making objects disappear since it will affect
701 the entire staff. This method also influences the spacing, which may or
702 may not be desirable. More sophisticated methods of blanking objects
703 are shown in @rlearning{Visibility and color of objects}.
705 The next example shows a practical application. Bar lines and time
706 signatures are normally synchronized across the score. This is done
707 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
708 This plug-in keeps an administration of time signature, location
709 within the measure, etc. By moving these engraver from @code{Score} to
710 @code{Staff} context, we can have a score where each staff has its own
713 @cindex polymetric scores
714 @cindex Time signatures, multiple
716 @lilypond[quote,verbatim]
720 \consists "Timing_translator"
721 \consists "Default_bar_line_engraver"
728 \consists "Timing_translator"
729 \consists "Default_bar_line_engraver"
739 \remove "Timing_translator"
740 \remove "Default_bar_line_engraver"
748 The order in which the engravers are specified is the order in
749 which they are called to carry out their processing. Usually the
750 order in which the engravers are specified does not matter, but in
751 a few special cases the order is important, for example where one
752 engraver writes a property and another reads it, or where one
753 engraver creates a grob and another must process it.
755 The following orderings are important:
759 the @code{Bar_engraver} must normally be first,
762 the @code{New_fingering_engraver} must come before the
763 @code{Script_column_engraver},
766 the @code{Timing_translator} must come before the
767 @code{Bar_number_engraver}.
773 @file{ly/engraver-init.ly}.
776 @node Changing context default settings
777 @subsection Changing context default settings
779 @cindex default context properties, changing
780 @cindex context properties, changing defaults
782 Context and grob properties can be changed with @code{\set}
783 and @code{\override} commands, as described in
784 @ref{Modifying properties}. These commands create music events,
785 making the changes take effect at the point in time the music
788 In contrast, this section explains how to change the @emph{default}
789 values of context and grob properties at the time the context is
790 created. There are two ways of doing this. One modifies the default
791 values in all contexts of a particular type, the other modifies the
792 default values in just one particular instance of a context.
795 * Changing all contexts of the same type::
796 * Changing just one specific context::
797 * Order of precedence::
800 @node Changing all contexts of the same type
801 @unnumberedsubsubsec Changing all contexts of the same type
803 @cindex \context in \layout block
807 The context settings which are to be used by default in
808 @code{Score}, @code{Staff}, @code{Voice} and other contexts may be
809 specified in a @code{\context} block within any @code{\layout} block.
810 The @code{\layout} block should be placed within the @code{\score}
811 block to which it is to apply, after the music.
817 [context settings for all Voice contexts]
821 [context settings for all Staff contexts]
826 The following types of settings may be specified:
830 An @code{\override} command, but with the context name omitted
832 @lilypond[quote,verbatim]
835 a4^"Thicker stems" a a a
841 \override Stem.thickness = #4.0
848 Directly setting a context property
850 @lilypond[quote,verbatim]
853 a4^"Smaller font" a a a
866 A predefined command such as @code{\dynamicUp} or a music
867 expression like @code{\accidentalStyle dodecaphonic}
869 @lilypond[quote,verbatim]
872 a4^"Dynamics above" a a a
882 \accidentalStyle dodecaphonic
889 A user-defined variable containing a @code{\with} block; for details
890 of the @code{\with} block see
891 @ref{Changing just one specific context}.
893 @lilypond[quote,verbatim]
894 StaffDefaults = \with {
901 a4^"Smaller font" a a a
916 Property-setting commands can be placed in a @code{\layout} block
917 without being enclosed in a @code{\context} block. Such settings
918 are equivalent to including the same property-setting commands at
919 the start of every context of the type specified. If no context
920 is specified @emph{every} bottom-level context is affected, see
921 @ref{Bottom-level contexts - voices}. The syntax of a
922 property-setting command in a @code{\layout} block is the same as
923 the same command written in the music stream.
925 @lilypond[quote,verbatim]
929 a4^"Smaller font" a a a
934 \accidentalStyle dodecaphonic
936 \override Voice.Stem.thickness = #4.0
942 @node Changing just one specific context
943 @unnumberedsubsubsec Changing just one specific context
948 The context properties of just one specific context instance can be
949 changed in a @code{\with} block. All other context instances of the
950 same type retain the default settings built into LilyPond and modified
951 by any @code{\layout} block within scope. The @code{\with} block
952 must be placed immediately after the @code{\new} @var{context-type}
956 \new Staff \with @{ [context settings for this context instance only] @}
962 The following types of settings may be specified:
966 An @code{\override} command, but with the context name omitted
968 @lilypond[quote,verbatim]
971 \new Voice \with { \override Stem.thickness = #4.0 }
974 a4^"Thick stems" a a a
983 Directly setting a context property
985 @lilypond[quote,verbatim]
990 a4^"Default font" a a a
994 \new Staff \with { fontSize = #-4 }
997 a4^"Smaller font" a a a
1006 A predefined command such as @code{\dynamicUp}
1008 @lilypond[quote,verbatim]
1014 a4^"Dynamics below" a a a
1019 \new Staff \with { \accidentalStyle dodecaphonic }
1021 \new Voice \with { \dynamicUp }
1024 a4^"Dynamics above" a a a
1035 @node Order of precedence
1036 @unnumberedsubsubsec Order of precedence
1038 The value of a property which applies at a particular time is
1039 determined as follows:
1043 if an @code{\override} or @code{\set} command in the input stream is
1044 in effect that value is used,
1047 otherwise the default value taken from a @code{\with} statement
1048 on the context initiation statement is used,
1051 otherwise the default value taken from the most recent appropriate
1052 @code{\context} block in the @code{\layout} blocks is used,
1055 otherwise the LilyPond built-in default is used.
1060 @rlearning{Modifying context properties}.
1063 @ref{Contexts explained},
1064 @ref{Bottom-level contexts - voices},
1065 @ref{The set command},
1066 @ref{The override command},
1067 @ref{The \layout block}.
1070 @node Defining new contexts
1071 @subsection Defining new contexts
1073 @cindex contexts, defining new
1074 @cindex engravers, including in contexts
1089 Specific contexts, like @code{Staff} and @code{Voice}, are made from
1090 simple building blocks. It is possible to create new types of
1091 contexts with different combinations of engraver plug-ins.
1093 The next example shows how to build a different type of
1094 @code{Voice} context from scratch. It will be similar to
1095 @code{Voice}, but only prints centered slash note heads. It can be used
1096 to indicate improvisation in jazz pieces,
1098 @lilypond[quote,ragged-right]
1099 \layout { \context {
1101 \type "Engraver_group"
1102 \consists "Note_heads_engraver"
1103 \consists "Rhythmic_column_engraver"
1104 \consists "Text_engraver"
1105 \consists "Pitch_squash_engraver"
1106 squashedPosition = #0
1107 \override NoteHead.style = #'slash
1108 \override Stem.transparent = ##t
1112 \accepts "ImproVoice"
1116 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1117 c4 c^"undress" c_"while playing :)" c }
1123 These settings are defined within a @code{\context} block inside a
1124 @code{\layout} block,
1134 In the following discussion, the example input shown should go in place
1135 of the @dots{} in the previous fragment.
1137 First it is necessary to define a name for the new context:
1143 Since it is similar to the @code{Voice} context, we want commands that
1144 work in (existing) @code{Voice} contexts to continue working. This is
1145 achieved by giving the new context an alias of @code{Voice},
1151 The context will print notes and instructive texts, so we need to add
1152 the engravers which provide this functionality, plus the engraver which
1153 groups notes, stems and rests which occur at the same musical moment
1157 \consists "Note_heads_engraver"
1158 \consists "Text_engraver"
1159 \consists "Rhythmic_column_engraver"
1162 The note heads should all be placed on the center line,
1165 \consists "Pitch_squash_engraver"
1166 squashedPosition = #0
1169 The @code{Pitch_squash_engraver} modifies note heads (created
1170 by the @code{Note_heads_engraver}) and sets their vertical
1171 position to the value of @code{squashedPosition}, in this
1172 case@tie{}@code{0}, the center line.
1174 The notes look like a slash, and have no stem,
1177 \override NoteHead.style = #'slash
1178 \override Stem.transparent = ##t
1181 All these plug-ins have to cooperate, and this is achieved with a
1182 special plug-in, which must be marked with the keyword @code{\type}.
1183 This should always be @code{Engraver_group}.
1186 \type "Engraver_group"
1189 Put together, we get
1194 \type "Engraver_group"
1195 \consists "Note_heads_engraver"
1196 \consists "Text_engraver"
1197 \consists "Rhythmic_column_engraver"
1198 \consists "Pitch_squash_engraver"
1199 squashedPosition = #0
1200 \override NoteHead.style = #'slash
1201 \override Stem.transparent = ##t
1207 Contexts form hierarchies. We want to place the @code{ImproVoice}
1208 context within the @code{Staff} context, just like normal @code{Voice}
1209 contexts. Therefore, we modify the @code{Staff} definition with the
1210 @code{\accepts} command,
1220 The opposite of @code{\accepts} is @code{\denies},
1221 which is sometimes needed when reusing existing context definitions.
1223 Putting both into a @code{\layout} block, like
1233 \accepts "ImproVoice"
1238 Then the output at the start of this subsection can be entered as
1246 c c_"while playing :)"
1254 Internals Reference:
1255 @rinternals{Engraver_group},
1256 @rinternals{Note_heads_engraver},
1257 @rinternals{Text_engraver},
1258 @rinternals{Rhythmic_column_engraver},
1259 @rinternals{Pitch_squash_engraver}.
1262 @node Context layout order
1263 @subsection Context layout order
1265 @cindex contexts, layout order
1269 Contexts are normally positioned in a system from top to bottom
1270 in the order in which they are encountered in the input file. When
1271 contexts are nested, the outer context will include inner nested
1272 contexts as specified in the input file, provided the inner contexts
1273 are included in the outer context's @qq{accepts} list. Nested
1274 contexts which are not included in the outer context's @qq{accepts}
1275 list will be repositioned below the outer context rather than nested
1278 The @qq{accepts} list of a context can be changed with the
1279 @code{\accepts} and @code{\denies} commands. @code{\accepts} adds a
1280 context to the @qq{accepts} list and @code{\denies} removes a context
1281 from the list. For example, it would not normally be desirable for
1282 chord names to be nested within a @code{Staff} context, so the
1283 @code{ChordNames} context is not included by default in the @qq{accepts}
1284 list of the @code{Staff} context, but if this were to be required it can
1287 @lilypond[verbatim,quote]
1291 \chords { d1:m7 b1:min7.5- }
1296 @lilypond[verbatim,quote]
1300 \chords { d1:m7 b1:min7.5- }
1305 \accepts "ChordNames"
1311 @code{\denies} is mainly used when a new context is being based on
1312 another, but the required nesting differs. For example, the
1313 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1314 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1315 context in the @qq{accepts} list.
1317 @cindex contexts, implicit
1318 @cindex implicit contexts
1319 @funindex \defaultchild
1321 Note that a context will be silently created implicitly if a
1322 command is encountered when there is no suitable context available
1325 Within a context definition, the type of subcontext to be
1326 implicitly created is specified using @code{\defaultchild}. A
1327 number of music events require a @samp{Bottom} context: when such
1328 an event is encountered, subcontexts are created recursively until
1329 reaching a context with no @samp{defaultchild} setting.
1331 Implicit context creation can at times give rise to unexpected new
1332 staves or scores. Using @code{\new} to create contexts explicitly
1333 avoids those problems.
1335 @cindex alignAboveContext
1336 @cindex alignBelowContext
1337 @funindex alignAboveContext
1338 @funindex alignBelowContext
1340 Sometimes a context is required to exist for just a brief period, a
1341 good example being the staff context for an ossia. This is usually
1342 achieved by introducing the context definition at the appropriate
1343 place in parallel with corresponding section of the main music.
1344 By default, the temporary context will be placed below all the
1345 existing contexts. To reposition it above the context called
1346 @qq{main}, it should be defined like this:
1349 @code{\new Staff \with @{ alignAboveContext = #"main" @} }
1352 A similar situation arises when positioning a temporary lyrics
1353 context within a multi-staved layout such as a @code{ChoirStaff},
1354 for example, when adding a second verse to a repeated section.
1355 By default the temporary lyrics context will be placed beneath the
1356 lower staves. By defining the temporary lyrics context with
1357 @code{alignBelowContext} it can be positioned correctly beneath
1358 the (named) lyrics context containing the first verse.
1360 Examples showing this repositioning of temporary contexts can be
1361 found elsewhere --- see @rlearning{Nesting music expressions},
1362 @ref{Modifying single staves} and @ref{Techniques specific to lyrics}.
1366 @rlearning{Nesting music expressions}.
1369 @ref{Modifying single staves},
1370 @ref{Techniques specific to lyrics}.
1373 @rprogram{An extra staff appears}.
1376 @file{ly/engraver-init.ly}.
1379 @node Explaining the Internals Reference
1380 @section Explaining the Internals Reference
1383 * Navigating the program reference::
1384 * Layout interfaces::
1385 * Determining the grob property::
1386 * Naming conventions::
1389 @node Navigating the program reference
1390 @subsection Navigating the program reference
1392 @c TODO remove this (it's in the LM)
1393 @c Replace with more factual directions
1395 Suppose we want to move the fingering indication in the fragment
1398 @lilypond[quote,relative=2,verbatim]
1404 If you visit the documentation on fingering instructions (in
1405 @ref{Fingering instructions}), you will notice:
1410 Internals Reference: @rinternals{Fingering}.
1415 @c outdated info; probably will delete.
1417 This fragment points to two parts of the program reference: a page
1418 on @code{FingeringEvent} and one on @code{Fingering}.
1420 The page on @code{FingeringEvent} describes the properties of the music
1421 expression for the input @w{@code{-2}}. The page contains many links
1422 forward. For example, it says
1425 Accepted by: @rinternals{Fingering_engraver},
1429 That link brings us to the documentation for the Engraver, the
1433 This engraver creates the following layout objects: @rinternals{Fingering}.
1436 In other words, once the @code{FingeringEvent}s are interpreted, the
1437 @code{Fingering_engraver} plug-in will process them.
1441 @c I can't figure out what this is supposed to mean. -gp
1443 The @code{Fingering_engraver} is also listed to create
1444 @rinternals{Fingering} objects,
1446 @c old info? it doesn't make any sense to me with our current docs.
1448 second bit of information listed under @b{See also} in the Notation
1453 The programmer's reference is available as an HTML document. It is
1454 highly recommended that you read it in HTML form, either online or
1455 by downloading the HTML documentation. This section will be much more
1456 difficult to understand if you are using the
1460 Follow the link to @rinternals{Fingering}. At the top of the
1464 Fingering objects are created by: @rinternals{Fingering_engraver} and
1465 @rinternals{New_fingering_engraver}.
1468 By following related links inside the program reference, we can follow the
1469 flow of information within the program:
1473 @item @rinternals{Fingering}:
1474 @rinternals{Fingering} objects are created by:
1475 @rinternals{Fingering_engraver}
1477 @item @rinternals{Fingering_engraver}:
1478 Music types accepted: @rinternals{fingering-event}
1480 @item @rinternals{fingering-event}:
1481 Music event type @code{fingering-event} is in Music expressions named
1482 @rinternals{FingeringEvent}
1485 This path goes against the flow of information in the program: it
1486 starts from the output, and ends at the input event. You could
1487 also start at an input event, and read with the flow of
1488 information, eventually ending up at the output object(s).
1490 The program reference can also be browsed like a normal document. It
1491 contains chapters on
1493 @rinternals{Music definitions},
1496 @code{Music definitions}
1498 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1499 chapter lists all the definitions used and all properties that may be
1503 @node Layout interfaces
1504 @subsection Layout interfaces
1506 @cindex interface, layout
1507 @cindex layout interface
1510 The HTML page that we found in the previous section describes the
1511 layout object called @rinternals{Fingering}. Such an object is a
1512 symbol within the score. It has properties that store numbers (like
1513 thicknesses and directions), but also pointers to related objects. A
1514 layout object is also called a @emph{Grob}, which is short for Graphical
1515 Object. For more details about Grobs, see @rinternals{grob-interface}.
1517 The page for @code{Fingering} lists the definitions for the
1518 @code{Fingering} object. For example, the page says
1521 @code{padding} (dimension, in staff space):
1527 which means that the number will be kept at a distance of at least 0.5
1531 Each layout object may have several functions as a notational or
1532 typographical element. For example, the Fingering object
1533 has the following aspects
1537 Its size is independent of the horizontal spacing, unlike slurs or beams.
1540 It is a piece of text. Granted, it is usually a very short text.
1543 That piece of text is typeset with a font, unlike slurs or beams.
1546 Horizontally, the center of the symbol should be aligned to the
1547 center of the note head.
1550 Vertically, the symbol is placed next to the note and the staff.
1553 The vertical position is also coordinated with other superscript
1554 and subscript symbols.
1557 Each of these aspects is captured in so-called @emph{interface}s,
1558 which are listed on the @rinternals{Fingering} page at the bottom
1561 This object supports the following interfaces:
1562 @rinternals{item-interface},
1563 @rinternals{self-alignment-interface},
1564 @rinternals{side-position-interface}, @rinternals{text-interface},
1565 @rinternals{text-script-interface}, @rinternals{font-interface},
1566 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1569 Clicking any of the links will take you to the page of the respective
1570 object interface. Each interface has a number of properties. Some of
1571 them are not user-serviceable (@q{Internal properties}), but others
1574 We have been talking of @emph{the} @code{Fingering} object, but actually it
1575 does not amount to much. The initialization file (see
1576 @rlearning{Other sources of information})
1577 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1582 (avoid-slur . around)
1583 (slur-padding . 0.2)
1584 (staff-padding . 0.5)
1585 (self-alignment-X . 0)
1586 (self-alignment-Y . 0)
1587 (script-priority . 100)
1588 (stencil . ,ly:text-interface::print)
1589 (direction . ,ly:script-interface::calc-direction)
1590 (font-encoding . fetaText)
1591 (font-size . -5) ; don't overlap when next to heads.
1592 (meta . ((class . Item)
1593 (interfaces . (finger-interface
1595 text-script-interface
1597 side-position-interface
1598 self-alignment-interface
1599 item-interface))))))
1603 As you can see, the @code{Fingering} object is nothing more than a
1604 bunch of variable settings, and the webpage in the Internals Reference
1605 is directly generated from this definition.
1608 @node Determining the grob property
1609 @subsection Determining the grob property
1611 @c TODO remove this (it's in the LM)
1612 @c Replace with more factual directions
1614 Recall that we wanted to change the position of the @b{2} in
1616 @lilypond[quote,relative=2,verbatim]
1622 Since the @b{2} is vertically positioned next to its note, we have to
1623 meddle with the interface associated with this positioning. This is
1624 done using @code{side-position-interface}. The page for this interface
1628 @code{side-position-interface}
1630 Position a victim object (this one) next to other objects (the
1631 support). The property @code{direction} signifies where to put the
1632 victim object relative to the support (left or right, up or down?)
1637 Below this description, the variable @code{padding} is described as
1642 (dimension, in staff space)
1644 Add this much extra space between objects that are next to each other.
1648 By increasing the value of @code{padding}, we can move the
1649 fingering away from the note head. The following command inserts
1650 3 staff spaces of white
1651 between the note and the fingering:
1653 \once \override Voice.Fingering.padding = #3
1656 Inserting this command before the Fingering object is created,
1657 i.e., before @code{c2}, yields the following result:
1659 @lilypond[quote,relative=2,verbatim]
1660 \once \override Voice.Fingering.padding = #3
1667 In this case, the context for this tweak is @code{Voice}. This
1668 fact can also be deduced from the program reference, for the page for
1669 the @rinternals{Fingering_engraver} plug-in says
1672 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1676 @node Naming conventions
1677 @subsection Naming conventions
1679 Another thing that is needed, is an overview of the various naming
1683 @item scheme functions: lowercase-with-hyphens (incl. one-word
1685 @item scheme functions: ly:plus-scheme-style
1686 @item music events, music classes and music properties:
1688 @item Grob interfaces: scheme-style
1689 @item backend properties: scheme-style (but X and Y!)
1690 @item contexts (and MusicExpressions and grobs): Capitalized or
1692 @item context properties: lowercaseFollowedByCamelCase
1694 Capitalized_followed_by_lowercase_and_with_underscores
1697 Questions to be answered:
1699 @item Which of these are conventions and which are rules?
1700 @item Which are rules of the underlying language, and which are
1704 @node Modifying properties
1705 @section Modifying properties
1707 @c TODO change the menu and subsection node names to use
1708 @c backslash once the new macro to handle the refs
1709 @c is available. Need to find and change all refs at
1710 @c the same time. -td
1713 * Overview of modifying properties::
1715 * The override command::
1716 * The tweak command::
1717 * set versus override::
1718 * Modifying alists::
1722 @node Overview of modifying properties
1723 @subsection Overview of modifying properties
1725 Each context is responsible for creating certain types of graphical
1726 objects. The settings used for printing these objects are also stored by
1727 context. By changing these settings, the appearance of objects can be
1730 There are two different kinds of properties stored in contexts:
1731 context properties and grob properties. Context properties are
1732 properties that apply to the context as a whole and control
1733 how the context itself is displayed. In contrast, grob properties
1734 apply to specific grob types that will be displayed in the context.
1736 The @code{\set} and @code{\unset} commands are used to change values
1737 for context properties. The @code{\override} and @code{\revert}
1738 commands are used to change values for grob properties.
1741 The syntax for this is
1744 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1747 Here @var{name} is the name of a graphical object, like
1748 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1749 variable of the formatting system (@q{grob property} or @q{layout
1750 property}). The latter is a symbol, so it must be quoted. The
1751 subsection @ref{Modifying properties}, explains what to fill in
1752 for @var{name}, @var{property}, and @var{value}. Here we only
1753 discuss the functionality of this command.
1758 \override Staff.Stem.thickness = #4.0
1762 makes stems thicker (the default is 1.3, with staff line thickness as a
1763 unit). Since the command specifies @code{Staff} as context, it only
1764 applies to the current staff. Other staves will keep their normal
1765 appearance. Here we see the command in action:
1767 @lilypond[quote,verbatim,relative=2]
1769 \override Staff.Stem.thickness = #4.0
1775 The @code{\override} command changes the definition of the @code{Stem}
1776 within the current @code{Staff}. After the command is interpreted
1777 all stems are thickened.
1779 Analogous to @code{\set}, the @var{context} argument may be left out,
1780 causing the default context @code{Voice} to be used. Adding
1781 @code{\once} applies the change during one timestep only.
1783 @lilypond[quote,verbatim,relative=2]
1785 \once \override Stem.thickness = #4.0
1790 The @code{\override} must be done before the object is
1791 started. Therefore, when altering @emph{Spanner} objects such as slurs
1792 or beams, the @code{\override} command must be executed at the moment
1793 when the object is created. In this example,
1795 @lilypond[quote,verbatim,relative=2]
1796 \override Slur.thickness = #3.0
1798 \override Beam.beam-thickness = #0.6
1803 the slur is fatter but the beam is not. This is because the command for
1804 @code{Beam} comes after the Beam is started, so it has no effect.
1806 Analogous to @code{\unset}, the @code{\revert} command for a context
1807 undoes an @code{\override} command; like with @code{\unset}, it only
1808 affects settings that were made in the same context. In other words, the
1809 @code{\revert} in the next example does not do anything.
1812 \override Voice.Stem.thickness = #4.0
1813 \revert Staff.Stem.thickness
1816 Some tweakable options are called @q{subproperties} and reside inside
1817 properties. To tweak those, use commands of the form
1819 @c leave this as a long long
1821 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1828 \override Stem.details.beamed-lengths = #'(4 4 3)
1834 Internals Reference:
1835 @rinternals{Backend},
1836 @rinternals{All layout objects},
1837 @rinternals{OverrideProperty},
1838 @rinternals{RevertProperty},
1839 @rinternals{PropertySet}.
1842 The back-end is not very strict in type-checking object properties.
1843 Cyclic references in Scheme values for properties can cause hangs
1844 or crashes, or both.
1847 @node The set command
1848 @subsection The @code{@bs{}set} command
1852 @cindex changing properties
1854 Each context has a set of @emph{properties}, variables contained
1855 in that context. Context properties are changed with the @code{\set}
1856 command, which has the following syntax:
1859 \set @var{context}.@var{property} = #@var{value}
1862 @var{value} is a Scheme object, which is why it must be preceded by
1863 the @code{#}@tie{}character.
1865 Contexts properties are usually named in
1866 @code{studlyCaps}. They mostly control the translation from
1867 music to notation, e.g. @code{localKeySignature} (for determining
1868 whether to print accidentals), or @code{measurePosition} (for
1869 determining when to print a bar line). Context properties can
1870 change value over time while interpreting a piece of music;
1871 @code{measurePosition} is an obvious example of
1872 this. Context properties are modified with @code{\set}.
1874 For example, multimeasure rests will be combined into a single bar
1875 if the context property @code{skipBars} is set to @code{#t}:
1877 @lilypond[quote,verbatim,relative=2]
1879 \set Score.skipBars = ##t
1883 If the @var{context} argument is left out, then the property will be
1884 set in the current bottom context (typically @code{ChordNames},
1885 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1887 @lilypond[quote,verbatim,relative=2]
1888 \set Score.autoBeaming = ##f
1892 \set autoBeaming = ##t
1900 The change is applied @q{on-the-fly}, during the music, so that the
1901 setting only affects the second group of eighth notes.
1903 Note that the bottom-most context does not always contain the property
1904 that you wish to change -- for example, attempting to set the
1905 @code{skipBars} property of the default bottom context, in this case
1906 @code{Voice}, will have no effect, because skipBars is a property of
1907 the @code{Score} context.
1909 @lilypond[quote,verbatim,relative=2]
1915 Contexts are hierarchical, so if an enclosing context was specified, for
1916 example @code{Staff}, then the change would also apply to all
1917 @code{Voice}s in the current staff.
1921 The @code{\unset} command:
1924 \unset @var{context}.@var{property}
1928 is used to remove the definition of @var{property} from
1929 @var{context}. This command removes
1930 the definition only if it is set in @var{context}.
1931 Properties that have been set in enclosing contexts will
1932 not be altered by an unset in an enclosed context:
1934 @lilypond[quote,verbatim,relative=2]
1935 \set Score.autoBeaming = ##t
1940 \unset Score.autoBeaming
1948 Like @code{\set}, the @var{context} argument does not have to be
1949 specified for a bottom context, so the two statements
1952 \set Voice.autoBeaming = ##t
1953 \set autoBeaming = ##t
1957 are equivalent if the current bottom context is @code{Voice}.
1961 Preceding a @code{\set} command by @code{\once} makes the
1962 setting apply to only a single time-step:
1964 @lilypond[quote,verbatim,relative=2]
1966 \once \set fontSize = #4.7
1971 A full description of all available context properties is in the
1972 internals reference, see
1974 @rinternals{Tunable context properties}.
1977 Translation @expansion{} Tunable context properties.
1981 Internals Reference:
1982 @rinternals{Tunable context properties}.
1985 @node The override command
1986 @subsection The @code{\override} command
1988 @cindex grob properties
1989 @cindex properties, grob
1992 There is a special type of context property: the grob
1993 description. Grob descriptions are named in @code{StudlyCaps}
1994 (starting with capital letters). They contain the
1995 @q{default settings} for a particular kind of grob as an
1996 association list. See @file{scm/define-grobs.scm}
1997 to see the settings for each grob description. Grob descriptions
1998 are modified with @code{\override}.
2000 The syntax for the @code{\override} command is
2003 \override [@var{context}.]@var{GrobName}.@var{property} = #@var{value}
2006 For example, we can increase the thickness of a note stem by
2007 overriding the @code{thickness} property of the @code{Stem}
2010 @lilypond[quote,verbatim,relative=2]
2012 \override Voice.Stem.thickness = #3.0
2016 If no context is specified in an @code{\override}, the bottom
2019 @lilypond[quote,verbatim,relative=2]
2020 { \override Staff.Stem.thickness = #3.0
2024 \override Stem.thickness = #0.5
2033 Some tweakable options are called @q{subproperties} and reside inside
2034 properties. To tweak those, use commands in the form
2037 \override Stem.details.beamed-lengths = #'(4 4 3)
2040 or to modify the ends of spanners, use a form like these
2043 \override TextSpanner.bound-details.left.text = #"left text"
2044 \override TextSpanner.bound-details.right.text = #"right text"
2048 @cindex reverting overrides
2049 @cindex overrides, reverting
2051 The effects of @code{\override} can be undone by @code{\revert}.
2053 The syntax for the @code{\revert} command is
2056 \revert [@var{context}.]@var{GrobName}.@var{property}
2061 @lilypond[quote,verbatim,relative=2]
2063 \override Voice.Stem.thickness = #3.0
2065 \revert Voice.Stem.thickness
2069 The effects of @code{\override} and @code{\revert} apply to all
2070 grobs in the affected context from the current time forward:
2072 @lilypond[quote,verbatim,relative=2]
2077 \override Staff.Stem.thickness = #3.0
2081 \revert Staff.Stem.thickness
2089 @cindex overriding for only one moment
2091 @code{\once} can be used with @code{\override}
2092 to affect only the current time step:
2094 @lilypond[quote,verbatim,relative=2]
2098 \override Stem.thickness = #3.0
2102 \once \override Stem.thickness = #3.0
2111 Commands which change output generally look like
2114 \override Voice.Stem.thickness = #3.0
2118 To construct this tweak we must determine these bits of information:
2121 @item the context: here @code{Voice}.
2122 @item the layout object: here @code{Stem}.
2123 @item the layout property: here @code{thickness}.
2124 @item a sensible value: here @code{3.0}.
2127 @cindex internal documentation
2128 @cindex finding graphical objects
2129 @cindex graphical object descriptions
2132 @cindex internal documentation
2134 For many properties, regardless of the data type of the property, setting the
2135 property to false (@code{#f}) will result in turning it off, causing
2136 LilyPond to ignore that property entirely. This is particularly useful for
2137 turning off grob properties which may otherwise be causing problems.
2139 We demonstrate how to glean this information from the notation manual
2140 and the program reference.
2144 Internals Reference:
2145 @rinternals{Backend}
2148 @node The tweak command
2149 @subsection The @code{\tweak} command
2154 Changing grob properties
2155 with @code{\override} causes the changes to apply to all of the
2156 given grobs in the context at the moment the change applies.
2157 Sometimes, however, it is desirable to have changes apply to just
2158 one grob, rather than to all grobs in the affected context. This is
2159 accomplished with the @code{\tweak} command, which has the following
2163 \tweak [@var{layout-object}.]@var{grob-property} @var{value}
2166 Specifying @var{layout-object} is optional.
2167 The @code{\tweak} command applies to the music object that immediately
2168 follows @var{value} in the music stream.
2171 In some cases, it is possible to take a short-cut for tuning
2172 graphical objects. For objects that are created directly from
2173 an item in the input file, you can use the @code{\tweak} command.
2176 @lilypond[relative=2,verbatim,quote]
2181 \tweak duration-log #1
2190 The main use of the @code{\tweak} command is to modify just
2191 one of a number of notation elements which start at the same musical
2192 moment, like the notes of a chord, or tuplet brackets which start
2195 The @code{\tweak} command sets a property in the following object
2196 directly, without requiring the grob name or context to be
2197 specified. For this to work, it is necessary for the @code{\tweak}
2198 command to remain immediately adjacent to the object to which it is
2199 to apply after the input file has been converted to a music stream.
2200 This is often not the case, as many additional elements are inserted
2201 into the music stream implicitly. For example, when a note which is
2202 not part of a chord is processed, LilyPond implicitly inserts a
2203 @code{ChordEvent} event before the note, so separating the tweak
2204 from the note. However, if chord symbols are placed round the
2205 tweak and the note, the @code{\tweak} command comes after the
2206 @code{ChordEvent} in the music stream, so remaining adjacent to the
2207 note, and able to modify it.
2211 @lilypond[relative=2,verbatim,quote]
2212 <\tweak color #red c>4
2218 @lilypond[relative=2,verbatim,quote]
2219 \tweak color #red c4
2224 For an introduction to the syntax and uses of the tweak command
2225 see @rlearning{Tweaking methods}.
2227 When several similar items are placed at the same musical moment,
2228 the @code{\override} command cannot be used to modify just one of
2229 them -- this is where the @code{\tweak} command must be used.
2230 Items which may appear more than once at the same musical moment
2231 include the following:
2233 @c TODO expand to include any further uses of \tweak
2235 @item note heads of notes inside a chord
2236 @item articulation signs on a single note
2237 @item ties between notes in a chord
2238 @item tuplet brackets starting at the same time
2241 @c TODO add examples of these
2243 @cindex chord, modifying one note in
2245 In this example, the color of one note head and the type of another
2246 note head are modified within a single chord:
2248 @lilypond[relative=2,verbatim,quote]
2253 \tweak duration-log #1
2258 @code{\tweak} can be used to modify slurs:
2260 @lilypond[verbatim,quote,relative=1]
2261 c-\tweak thickness #5 ( d e f)
2265 For the @code{\tweak} command to work, it must
2266 remain immediately adjacent to the object to which it is
2267 to apply after the input file has been converted to a music stream.
2268 Tweaking a whole chord does not do anything since its music event
2269 only acts as a container, and all layout objects are created from events
2270 inside of the @code{EventChord}:
2272 @lilypond[relative=2,verbatim,quote]
2273 \tweak color #red c4
2274 \tweak color #red <c e>4
2275 <\tweak color #red c e>4
2278 The simple @code{\tweak} command cannot be used to modify any object
2279 that is not directly created from the input. In particular
2280 it will not affect stems, automatic
2281 beams or accidentals, since these are generated later by
2282 @code{NoteHead} layout objects rather than by music elements in the
2285 Such indirectly created layout objects can be tweaked using the form
2286 of the @code{\tweak} command in which the grob name is specified
2289 @lilypond[relative=2,verbatim,quote]
2290 \tweak Stem.color #red
2291 \tweak Beam.color #green c8 e
2292 <c e \tweak Accidental.font-size #-3 ges>4
2295 @code{\tweak} cannot be used to modify clefs or time
2296 signatures, since these become separated from any preceding
2297 @code{\tweak} command in the input stream by the automatic
2298 insertion of extra elements required to specify the context.
2300 Several @code{\tweak} commands may be placed before a
2301 notational element -- all affect it:
2303 @lilypond[verbatim,quote,relative=1]
2305 -\tweak style #'dashed-line
2306 -\tweak dash-fraction #0.2
2307 -\tweak thickness #3
2313 The music stream which is generated from a section of an input file,
2314 including any automatically inserted elements, may be examined,
2315 see @rextend{Displaying music expressions}. This may be helpful in
2316 determining what may be modified by a @code{\tweak} command, or
2317 in determining how to adjust the input to make a @code{\tweak}
2322 @rlearning{Tweaking methods}.
2325 @rextend{Displaying music expressions}.
2329 @cindex tweaking control points
2330 @cindex control points, tweaking
2332 The @code{\tweak} command cannot be used to modify the control
2333 points of just one of several ties in a chord, other than the first
2334 one encountered in the input file.
2336 @node set versus override
2337 @subsection @code{\set} vs. @code{\override}
2339 @c TODO -- This section is probably unnecessary now.
2342 We have seen two methods of changing properties: @code{\set} and
2343 @code{\override}. There are actually two different kinds of
2346 @code{fontSize} is a special property: it is equivalent to
2347 entering @code{\override @dots{} #'font-size} for all pertinent
2348 objects. Since this is a common change, the special
2349 property (modified with @code{\set}) was created.
2354 @node Modifying alists
2355 @subsection Modifying alists
2357 Some user-configurable properties are internally represented as
2358 @emph{alists} (association lists), which store pairs of
2359 @emph{keys} and @emph{values}. The structure of an alist is:
2362 '((@var{key1} . @var{value1})
2363 (@var{key2} . @var{value2})
2364 (@var{key3} . @var{value3})
2368 If an alist is a grob property or @code{\paper} variable, its keys
2369 can be modified individually without affecting other keys.
2371 For example, to reduce the space between adjacent staves in a
2372 staff-group, use the @code{staff-staff-spacing} property of the
2373 @code{StaffGrouper} grob. The property is an alist with four
2374 keys: @code{basic-distance}, @code{minimum-distance},
2375 @code{padding}, and @code{stretchability}. The standard settings
2376 for this property are listed in the @qq{Backend} section of the
2377 Internals Reference (see @rinternals{StaffGrouper}):
2380 '((basic-distance . 9)
2381 (minimum-distance . 7)
2383 (stretchability . 5))
2386 One way to bring the staves closer together is by reducing the
2387 value of the @code{basic-distance} key (@code{9}) to match the
2388 value of @code{minimum-distance} (@code{7}). To modify a single
2389 key individually, use a @emph{nested declaration}:
2391 @lilypond[quote,verbatim]
2392 % default space between staves
2394 \new Staff { \clef treble c''1 }
2395 \new Staff { \clef bass c1 }
2398 % reduced space between staves
2399 \new PianoStaff \with {
2400 % this is the nested declaration
2401 \override StaffGrouper.staff-staff-spacing.basic-distance = #7
2403 \new Staff { \clef treble c''1 }
2404 \new Staff { \clef bass c1 }
2408 Using a nested declaration will update the specified key (such as
2409 @code{basic-distance} in the above example) without altering any
2410 other keys already set for the same property.
2412 Now suppose we want the staves to be as close as possible without
2413 overlapping. The simplest way to do this is to set all four alist
2414 keys to zero. However, it is not necessary to enter four nested
2415 declarations, one for each key. Instead, the property can be
2416 completely re-defined with one declaration, as an alist:
2418 @lilypond[quote,verbatim]
2419 \new PianoStaff \with {
2420 \override StaffGrouper.staff-staff-spacing =
2421 #'((basic-distance . 0)
2422 (minimum-distance . 0)
2424 (stretchability . 0))
2426 \new Staff { \clef treble c''1 }
2427 \new Staff { \clef bass c1 }
2431 Note that any keys not explicitly listed in the alist definition
2432 will be reset to their @emph{default-when-unset} values. In the
2433 case of @code{staff-staff-spacing}, any unset key-values would be
2434 reset to zero (except @code{stretchability}, which takes the value
2435 of @code{basic-distance} when unset). Thus the following two
2436 declarations are equivalent:
2439 \override StaffGrouper.staff-staff-spacing =
2440 #'((basic-distance . 7))
2442 \override StaffGrouper.staff-staff-spacing =
2443 #'((basic-distance . 7)
2444 (minimum-distance . 0)
2446 (stretchability . 7))
2449 One (possibly unintended) consequence of this is the removal of
2450 any standard settings that are set in an initialization file and
2451 loaded each time an input file is compiled. In the above example,
2452 the standard settings for @code{padding} and
2453 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2454 are reset to their default-when-unset values (zero for both keys).
2455 Defining a property or variable as an alist (of any size) will
2456 always reset all unset key-values to their default-when-unset
2457 values. Unless this is the intended result, it is safer to update
2458 key-values individually with a nested declaration.
2460 @warning{Nested declarations will not work for context property
2461 alists (such as @code{beamExceptions}, @code{keySignature},
2462 @code{timeSignatureSettings}, etc.). These properties can only be
2463 modified by completely re-defining them as alists.}
2466 @node Useful concepts and properties
2467 @section Useful concepts and properties
2472 * Direction and placement::
2473 * Distances and measurements::
2474 * Staff symbol properties::
2476 * Visibility of objects::
2478 * Rotating objects::
2482 @subsection Input modes
2484 The way in which the notation contained within an input file is
2485 interpreted is determined by the current input mode.
2489 This is activated with the @code{\chordmode} command, and causes
2490 input to be interpreted with the syntax of chord notation, see
2491 @ref{Chord notation}. Chords are rendered as notes on a staff.
2493 Chord mode is also activated with the @code{\chords} command.
2494 This also creates a new @code{ChordNames} context and
2495 causes the following input to be interpreted with the syntax of
2496 chord notation and rendered as chord names in the @code{ChordNames}
2497 context, see @ref{Printing chord names}.
2501 This is activated with the @code{\drummode} command, and causes
2502 input to be interpreted with the syntax of drum notation, see
2503 @ref{Basic percussion notation}.
2505 Drum mode is also activated with the @code{\drums} command.
2506 This also creates a new @code{DrumStaff} context and causes the
2507 following input to be interpreted with the syntax of drum notation
2508 and rendered as drum symbols on a drum staff, see @ref{Basic
2509 percussion notation}.
2511 @strong{Figure mode}
2513 This is activated with the @code{\figuremode} command, and causes
2514 input to be interpreted with the syntax of figured bass, see
2515 @ref{Entering figured bass}.
2517 Figure mode is also activated with the @code{\figures} command.
2518 This also creates a new @code{FiguredBass} context and causes the
2519 following input to be interpreted with the figured bass syntax
2520 and rendered as figured bass symbols in the @code{FiguredBass}
2521 context, see @ref{Introduction to figured bass}.
2523 @strong{Fret and tab modes}
2525 There are no special input modes for entering fret and tab symbols.
2527 To create tab diagrams, enter notes or chords in note mode and
2528 render them in a @code{TabStaff} context, see
2529 @ref{Default tablatures}.
2531 To create fret diagrams above a staff, you have two choices.
2532 You can either use the @code{FretBoards} context (see
2533 @ref{Automatic fret diagrams} or you can enter them as a markup
2534 above the notes using the @code{\fret-diagram} command (see
2535 @ref{Fret diagram markups}).
2537 @strong{Lyrics mode}
2539 This is activated with the @code{\lyricmode} command, and causes
2540 input to be interpreted as lyric syllables with optional durations
2541 and associated lyric modifiers, see @ref{Vocal music}.
2543 Lyric mode is also activated with the @code{\addlyrics} command.
2544 This also creates a new @code{Lyrics} context and an implicit
2545 @code{\lyricsto} command which associates the following lyrics
2546 with the preceding music.
2548 @strong{Markup mode}
2550 This is activated with the @code{\markup} command, and causes
2551 input to be interpreted with the syntax of markup, see
2552 @ref{Text markup commands}.
2554 @c silly work-around for texinfo broken-ness
2555 @c (@strong{Note...} causes a spurious cross-reference in Info)
2558 This is the default mode or it may be activated with the
2559 @code{\notemode} command. Input is interpreted as pitches,
2560 durations, markup, etc and typeset as musical notation on a staff.
2562 It is not normally necessary to specify note mode explicitly, but
2563 it may be useful to do so in certain situations, for example if you
2564 are in lyric mode, chord mode or any other mode and want to insert
2565 something that only can be done with note mode syntax.
2567 For example, to indicate dynamic markings for the verses of a
2568 choral pieces it is necessary to enter note mode to interpret
2571 @lilypond[verbatim,relative=2,quote]
2574 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2578 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2585 @node Direction and placement
2586 @subsection Direction and placement
2588 In typesetting music the direction and placement of many items is
2589 a matter of choice. For example, the stems of notes can
2590 be directed up or down; lyrics, dynamics, and other expressive
2591 marks may be placed above or below the staff; text may be aligned
2592 left, right or center; etc. Most of these choices may be left to
2593 be determined automatically by LilyPond, but in some cases it may
2594 be desirable to force a particular direction or placement.
2597 * Articulation direction indicators::
2598 * The direction property::
2601 @node Articulation direction indicators
2602 @unnumberedsubsubsec Articulation direction indicators
2604 By default some directions are always up or always down (e.g.
2605 dynamics or fermata), while other things can alternate between
2606 up or down based on the stem direction (like slurs or accents).
2608 @c TODO Add table showing these
2610 The default action may be overridden by prefixing the articulation
2611 by a @emph{direction indicator}. Three direction indicators are
2612 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2613 and @code{-} (meaning @qq{use default direction}). The direction
2614 indicator can usually be omitted, in which case @code{-} is assumed,
2615 but a direction indicator is @strong{always} required before
2618 @item @code{\tweak} commands
2619 @item @code{\markup} commands
2620 @item @code{\tag} commands
2621 @item string markups, e.g. -"string"
2622 @item fingering instructions, e.g. @w{@code{-1}}
2623 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2626 Direction indicators affect only the next note:
2628 @lilypond[verbatim,quote,relative=2]
2635 @node The direction property
2636 @unnumberedsubsubsec The direction property
2638 The position or direction of many layout objects is controlled by the
2639 @code{direction} property.
2641 The value of the @code{direction} property may be set to @code{1},
2642 meaning @qq{up} or @qq{above}, or to @w{@code{-1}}, meaning @qq{down} or
2643 @qq{below}. The symbols @code{UP} and @code{DOWN} may be used instead
2644 of @code{1} and @w{@code{-1}} respectively. The default direction may
2645 be specified by setting @code{direction} to @code{0} or @code{CENTER}.
2646 Alternatively, in many cases predefined commands exist to specify the
2647 direction. These are of the form
2650 @code{\xxxUp}, @code{\xxxDown} or @code{\xxxNeutral}
2654 where @code{\xxxNeutral} means @qq{use the default} direction.
2655 See @rlearning{Within-staff objects}.
2657 In a few cases, arpeggio for example, the value of the @code{direction}
2658 property can specify whether the object is to be placed to the right or
2659 left of the parent. In this case @w{@code{-1}} or @code{LEFT} means
2660 @qq{to the left} and @code{1} or @code{RIGHT} means @qq{to the right}.
2661 @code{0} or @code{CENTER} means @qq{use the default} direction.
2664 These all have side-axis set to #X
2665 AmbitusAccidental - direction has no effect
2667 StanzaNumber - not tried
2668 TrillPitchAccidental - not tried
2669 TrillPitchGroup - not tried
2672 These indications affect all notes until they are canceled.
2674 @lilypond[verbatim,quote,relative=2]
2683 In polyphonic music, it is generally better to specify an explicit
2684 @code{voice} than change an object's direction. For more information.
2685 See @ref{Multiple voices}.
2689 @rlearning{Within-staff objects}.
2692 @ref{Multiple voices}.
2695 @node Distances and measurements
2696 @subsection Distances and measurements
2698 @cindex distances, absolute
2699 @cindex distances, scaled
2706 Distances in LilyPond are of two types: absolute and scaled.
2708 Absolute distances are used for specifying margins, indents, and
2709 other page layout details, and are by default specified in
2710 millimeters. Distances may be specified in other units by
2711 following the quantity by @code{\mm}, @code{\cm},
2712 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2713 an inch). Page layout distances can also be specified in scalable
2714 units (see the following paragraph) by appending
2715 @code{\staff-space} to the quantity. Page layout is described in
2716 detail in @ref{Page layout}.
2718 Scaled distances are always specified in units of the staff-space
2719 or, rarely, the half staff-space. The staff-space is the distance
2720 between two adjacent staff lines. The default value can be changed
2721 globally by setting the global staff size, or it can be overridden
2722 locally by changing the @code{staff-space} property of
2723 @code{StaffSymbol}. Scaled distances automatically scale with any
2724 change to the either the global staff size or the
2725 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2726 automatically only with changes to the global staff size.
2727 The global staff size thus enables the overall size of a rendered
2728 score to be easily varied. For the methods of setting the global
2729 staff size see @ref{Setting the staff size}.
2733 If just a section of a score needs to be rendered to a different
2734 scale, for example an ossia section or a footnote, the global staff
2735 size cannot simply be changed as this would affect the entire score.
2736 In such cases the change in size is made by overriding both the
2737 @code{staff-space} property of @code{StaffSymbol} and the size of
2738 the fonts. A Scheme function, @code{magstep}, is available to
2739 convert from a font size change to the equivalent change in
2740 @code{staff-space}. For an explanation and an example of its use,
2741 see @rlearning{Length and thickness of objects}.
2745 @rlearning{Length and thickness of objects}.
2749 @ref{Setting the staff size}.
2752 @node Staff symbol properties
2753 @subsection Staff symbol properties
2755 @cindex adjusting staff symbol
2756 @cindex drawing staff symbol
2757 @cindex staff symbol, setting of
2759 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2760 @c Need to think of uses for these properties. Eg 'line-positions
2761 @c is used in a snippet to thicken centre line.
2762 @c If retained, add @ref to here in 1.6.2 -td
2764 The vertical position of staff lines and the number of staff lines
2765 can be defined at the same time. As the following example shows,
2766 note positions are not influenced by the staff line positions.
2768 @warning{The @code{'line-positions} property overrides the
2769 @code{'line-count} property. The number of staff lines is
2770 implicitly defined by the number of elements in the list of values
2771 for @code{'line-positions}.}
2773 @lilypond[verbatim,quote,relative=1]
2775 \override StaffSymbol.line-positions = #'(7 3 0 -4 -6 -7)
2780 The width of a staff can be modified. The units are staff
2781 spaces. The spacing of objects inside the staff is not affected by
2784 @lilypond[verbatim,quote,relative=1]
2786 \override StaffSymbol.width = #23
2793 @subsection Spanners
2795 Many objects of musical notation extend over several notes or even
2796 several bars. Examples are slurs, beams, tuplet brackets, volta
2797 repeat brackets, crescendi, trills, and glissandi. Such objects
2798 are collectively called @qq{spanners}, and have special properties to control
2799 their appearance and behaviour. Some of these properties are common
2800 to all spanners; others are restricted to a sub-set of the spanners.
2802 All spanners support the @code{spanner-interface}. A few, essentially
2803 those that draw a straight line between the two objects, support in
2804 addition the @code{line-spanner-interface}.
2807 * Using the spanner-interface::
2808 * Using the line-spanner-interface::
2811 @node Using the spanner-interface
2812 @unnumberedsubsubsec Using the @code{spanner-interface}
2814 This interface provides two properties that apply to several spanners.
2816 @subsubsubheading The @code{minimum-length} property
2818 The minimum length of the spanner is specified by the
2819 @code{minimum-length} property. Increasing this usually has the
2820 necessary effect of increasing the spacing of the notes between the
2821 two end points. However, this override has no effect on
2822 many spanners, as their length is determined by other considerations.
2823 A few examples where it is effective are shown below.
2833 Works as long as callback is made:
2837 Works not at all for:
2846 @lilypond[verbatim,quote,relative=2]
2849 % increase the length of the tie
2850 -\tweak minimum-length #5
2854 @lilypond[verbatim,quote,relative=2]
2856 \compressFullBarRests
2858 % increase the length of the rest bar
2859 \once \override MultiMeasureRest.minimum-length = #20
2864 @lilypond[verbatim,quote,relative=2]
2866 % increase the length of the hairpin
2867 \override Hairpin.minimum-length = #20
2871 This override can also be used to increase the length of slurs and
2874 @lilypond[verbatim,quote,relative=2]
2877 -\tweak minimum-length #5
2882 -\tweak minimum-length #5
2886 For some layout objects, the @code{minimum-length} property becomes
2887 effective only if the @code{set-spacing-rods} procedure is called
2888 explicitly. To do this, the @code{springs-and-rods} property should
2889 be set to @code{ly:spanner::set-spacing-rods}. For example,
2890 the minimum length of a glissando has no effect unless the
2891 @code{springs-and-rods} property is set:
2893 @lilypond[verbatim,quote,relative=1]
2897 % not effective alone
2898 \once \override Glissando.minimum-length = #20
2901 % effective only when both overrides are present
2902 \once \override Glissando.minimum-length = #20
2903 \once \override Glissando.springs-and-rods = #ly:spanner::set-spacing-rods
2907 The same is true of the @code{Beam} object:
2909 @lilypond[verbatim,quote,relative=1]
2910 % not effective alone
2911 \once \override Beam.minimum-length = #20
2914 % effective only when both overrides are present
2915 \once \override Beam.minimum-length = #20
2916 \once \override Beam.springs-and-rods = #ly:spanner::set-spacing-rods
2920 @subsubsubheading The @code{to-barline} property
2922 The second useful property of the @code{spanner-interface} is
2923 @code{to-barline}. By default this is true, causing hairpins and
2924 other spanners which are terminated on the first note of a measure to
2925 end instead on the immediately preceding bar line. If set to false,
2926 the spanner will extend beyond the bar line and end on the note
2929 @lilypond[verbatim,quote,relative=2]
2930 a \< a a a a \! a a a \break
2931 \override Hairpin.to-barline = ##f
2932 a \< a a a a \! a a a
2935 This property is not effective for all spanners. For example,
2936 setting it to @code{#t} has no effect on slurs or phrasing slurs
2937 or on other spanners for which terminating on the bar line would
2940 @node Using the line-spanner-interface
2941 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2943 Objects which support the @code{line-spanner-interface} include
2946 @item @code{DynamicTextSpanner}
2947 @item @code{Glissando}
2948 @item @code{TextSpanner}
2949 @item @code{TrillSpanner}
2950 @item @code{VoiceFollower}
2953 The routine responsible for drawing the stencils for these spanners is
2954 @code{ly:line-interface::print}. This routine determines the
2955 exact location of the two end points and draws a line
2956 between them, in the style requested. The locations of the two
2957 end points of the spanner are computed on-the-fly, but it is
2958 possible to override their Y-coordinates. The
2959 properties which need to be specified are nested
2960 two levels down within the property hierarchy, but the syntax of
2961 the @code{\override} command is quite simple:
2963 @lilypond[relative=2,quote,verbatim]
2965 \once \override Glissando.bound-details.left.Y = #3
2966 \once \override Glissando.bound-details.right.Y = #-2
2970 The units for the @code{Y} property are @code{staff-space}s,
2971 with the center line of the staff being the zero point.
2972 For the glissando, this is the value for @code{Y} at the
2973 X-coordinate corresponding to the center point of each note head,
2974 if the line is imagined to be extended to there.
2976 If @code{Y} is not set, the value is computed from the vertical
2977 position of the corresponding attachment point of the spanner.
2979 In case of a line break, the values for the end points are
2980 specified by the @code{left-broken} and @code{right-broken}
2981 sub-lists of @code{bound-details}. For example:
2983 @lilypond[relative=2,ragged-right,verbatim,quote]
2984 \override Glissando.breakable = ##t
2985 \override Glissando.bound-details.right-broken.Y = #-3
2986 c1 \glissando \break
2991 A number of further properties of the @code{left} and
2992 @code{right} sub-lists of the @code{bound-details} property
2993 may be modified in the same way as @code{Y}:
2997 This sets the Y-coordinate of the end point, in @code{staff-space}s
2998 offset from the staff center line. By default, it is the center of
2999 the bound object, so a glissando points to the vertical center of
3002 For horizontal spanners, such as text spanners and trill spanners,
3003 it is hardcoded to 0.
3006 This determines where the line starts and ends in the X-direction,
3007 relative to the bound object. So, a value of @w{@code{-1}} (or
3008 @code{LEFT}) makes the line start/end at the left side of the note
3009 head it is attached to.
3012 This is the absolute X-coordinate of the end point. It is usually
3013 computed on the fly, and overriding it has little useful effect.
3016 Line spanners may have symbols at the beginning or end, which is
3017 contained in this sub-property. This is for internal use; it is
3018 recommended that @code{text} be used instead.
3021 This is a markup that is evaluated to yield the stencil. It is used
3022 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
3024 @lilypond[quote,ragged-right,relative=2,verbatim]
3025 \override TextSpanner.bound-details.left.text
3026 = \markup { \small \bold Slower }
3027 c2\startTextSpan b c a\stopTextSpan
3030 @item stencil-align-dir-y
3031 @item stencil-offset
3032 Without setting one of these, the stencil is simply put at the
3033 end-point, centered on the line, as defined by the @code{X} and
3034 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
3035 or @code{stencil-offset} will move the symbol at the edge vertically
3036 relative to the end point of the line:
3038 @lilypond[relative=1,quote,verbatim]
3039 \override TextSpanner.bound-details.left.stencil-align-dir-y = #-2
3040 \override TextSpanner.bound-details.right.stencil-align-dir-y = #UP
3042 \override TextSpanner.bound-details.left.text = #"ggg"
3043 \override TextSpanner.bound-details.right.text = #"hhh"
3044 c4^\startTextSpan c c c \stopTextSpan
3047 Note that negative values move the text @emph{up}, contrary to the
3048 effect that might be expected, as a value of @w{@code{-1}} or
3049 @code{DOWN} means align the @emph{bottom} edge of the text with
3050 the spanner line. A value of @code{1} or @code{UP} aligns
3051 the top edge of the text with the spanner line.
3054 Setting this sub-property to @code{#t} produces an arrowhead at the
3058 This sub-property controls the space between the specified
3059 end point of the line and the actual end. Without padding, a
3060 glissando would start and end in the center of each note head.
3064 The music function @code{\endSpanners} terminates the spanner
3065 which starts on the immediately following note prematurely. It
3066 is terminated after exactly one note, or at the following bar line
3067 if @code{to-barline} is true and a bar line occurs before the next
3070 @lilypond[verbatim,quote,ragged-right,relative=2]
3072 c2 \startTextSpan c2 c2
3077 When using @code{\endSpanners} it is not necessary to close
3078 \startTextSpan with \stopTextSpan, nor is it necessary to close
3079 hairpins with @code{\!}.
3082 Internals Reference:
3083 @rinternals{TextSpanner},
3084 @rinternals{Glissando},
3085 @rinternals{VoiceFollower},
3086 @rinternals{TrillSpanner},
3087 @rinternals{line-spanner-interface}.
3090 @node Visibility of objects
3091 @subsection Visibility of objects
3093 @cindex objects, visibility of
3094 @cindex grobs, visibility of
3095 @cindex visibility of objects
3097 There are four main ways in which the visibility of layout objects
3098 can be controlled: their stencil can be removed, they can be made
3099 transparent, they can be colored white, or their
3100 @code{break-visibility} property can be overridden. The first
3101 three apply to all layout objects; the last to just a few -- the
3102 @emph{breakable} objects. The Learning Manual introduces these
3103 four techniques, see @rlearning{Visibility and color of objects}.
3105 There are also a few other techniques which are specific to
3106 certain layout objects. These are covered under Special
3110 * Removing the stencil::
3111 * Making objects transparent::
3112 * Painting objects white::
3113 * Using break-visibility::
3114 * Special considerations::
3118 @node Removing the stencil
3119 @unnumberedsubsubsec Removing the stencil
3121 @cindex stencil, removing
3123 Every layout object has a stencil property. By default this is set
3124 to the specific function which draws that object. If this property
3125 is overridden to @code{#f} no function will be called and the object
3126 will not be drawn. The default action can be recovered with
3129 @lilypond[quote,verbatim,relative=1]
3131 \override Score.BarLine.stencil = ##f
3133 \revert Score.BarLine.stencil
3137 @node Making objects transparent
3138 @unnumberedsubsubsec Making objects transparent
3140 @cindex transparent, making objects
3142 Every layout object has a transparent property which by default is
3143 set to @code{#f}. If set to @code{#t} the object still occupies
3144 space but is made invisible.
3146 @lilypond[quote,verbatim,relative=2]
3148 \once \override NoteHead.transparent = ##t
3152 @node Painting objects white
3153 @unnumberedsubsubsec Painting objects white
3155 @cindex objects, coloring
3156 @cindex coloring objects
3158 @cindex printing order
3159 @cindex overwriting objects
3160 @cindex objects, overwriting
3161 @cindex grobs, overwriting
3163 Every layout object has a color property which by default is set
3164 to @code{black}. If this is overridden to @code{white} the object
3165 will be indistinguishable from the white background. However,
3166 if the object crosses other objects the color of the crossing
3167 points will be determined by the order in which they are drawn,
3168 and this may leave a ghostly image of the white object, as shown
3171 @lilypond[quote,verbatim,relative=2]
3172 \override Staff.Clef.color = #white
3176 This may be avoided by changing the order of printing the objects.
3177 All layout objects have a @code{layer} property which should be set
3178 to an integer. Objects with the lowest value of @code{layer} are
3179 drawn first, then objects with progressively higher values are drawn,
3180 so objects with higher values overwrite objects with lower values.
3181 By default most objects are assigned a @code{layer} value of
3182 @code{1}, although a few objects, including @code{StaffSymbol} and
3183 @code{BarLine}, are assigned a value of @code{0}. The order of
3184 printing objects with the same value of @code{layer} is indeterminate.
3186 In the example above the white clef, with a default @code{layer}
3187 value of @code{1}, is drawn after the staff lines (default
3188 @code{layer} value @code{0}), so overwriting them. To change this,
3189 the @code{Clef} object must be given in a lower value of
3190 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
3192 @lilypond[quote,verbatim,relative=2]
3193 \override Staff.Clef.color = #white
3194 \override Staff.Clef.layer = #-1
3198 @node Using break-visibility
3199 @unnumberedsubsubsec Using break-visibility
3201 @c TODO Add making other objects breakable
3203 @cindex break-visibility
3205 Most layout objects are printed only once, but some like
3206 bar lines, clefs, time signatures and key signatures, may need
3207 to be printed twice when a line break occurs -- once at the end
3208 of the line and again at the start of the next line. Such
3209 objects are called @emph{breakable}, and have a property, the
3210 @code{break-visibility} property to control their visibility
3211 at the three positions in which they may appear -- at the
3212 start of a line, within a line if they are changed, and at the
3213 end of a line if a change takes place there.
3215 For example, the time signature
3216 by default will be printed at the start of the first line, but
3217 nowhere else unless it changes, when it will be printed at the
3218 point at which the change occurs. If this change occurs at the
3219 end of a line the new time signature will be printed at the start
3220 of the next line and a cautionary time signature will be printed
3221 at the end of the previous line as well.
3223 This behaviour is controlled by the @code{break-visibility}
3224 property, which is explained in
3225 @c Leave this ref on a newline - formats incorrectly otherwise -td
3226 @rlearning{Visibility and color of objects}. This property takes
3227 a vector of three booleans which, in order, determine whether the
3228 object is printed at the end of, within the body of, or at the
3229 beginning of a line. Or to be more precise, before a line break,
3230 where there is no line break, or after a line break.
3232 Alternatively, these eight combinations may be specified
3233 by pre-defined functions, defined in @file{scm/output-lib.scm},
3234 where the last three columns indicate whether the layout objects
3235 will be visible in the positions shown at the head of the columns:
3237 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {Before} {At no} {After}
3238 @headitem Function @tab Vector @tab Before @tab At no @tab After
3239 @headitem form @tab form @tab break @tab break @tab break
3241 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
3242 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
3243 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
3244 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
3245 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
3246 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
3247 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
3248 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
3251 The default settings of @code{break-visibility} depend on the
3252 layout object. The following table shows all the layout objects
3253 of interest which are affected by @code{break-visibility} and the
3254 default setting of this property:
3256 @multitable @columnfractions .3 .3 .4
3258 @headitem Layout object @tab Usual context @tab Default setting
3260 @c omit Ambitus as it appears not to be affected by break-visibility -td
3261 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
3262 @item @code{BarLine} @tab @code{Score} @tab calculated
3263 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
3264 @c omit the following item until it can be explained -td
3265 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
3266 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3267 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
3268 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
3269 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3270 @item @code{KeyCancellation} @tab @code{Staff} @tab @code{begin-of-line-invisible}
3271 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
3272 @c omit LeftEdge until it can be explained -td
3273 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
3274 @item @code{ClefModifier} @tab @code{Staff} @tab @code{begin-of-line-visible}
3275 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
3276 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
3280 The example below shows the use of the vector form to control the
3281 visibility of bar lines:
3283 @lilypond[quote,verbatim,relative=1,ragged-right]
3286 % Remove bar line at the end of the current line
3287 \once \override Score.BarLine.break-visibility = ##(#f #t #t)
3293 Although all three components of the vector used to override
3294 @code{break-visibility} must be present, not all of them are
3295 effective with every layout object, and some combinations may
3296 even give errors. The following limitations apply:
3299 @item Bar lines cannot be printed at start of line.
3300 @item A bar number cannot be printed at the start of the first
3301 line unless it is set to be different from 1.
3302 @item Clef -- see below
3303 @item Double percent repeats are either all printed or all
3304 suppressed. Use begin-of line-invisible to print and
3305 all-invisible to suppress.
3306 @item Key signature -- see below
3307 @item ClefModifier -- see below
3310 @node Special considerations
3311 @unnumberedsubsubsec Special considerations
3313 @subsubsubheading Visibility following explicit changes
3315 @cindex key signature, visibility following explicit change
3316 @cindex explicitKeySignatureVisibility
3317 @cindex clef, visibility following explicit change
3318 @cindex explicitClefVisibility
3320 The @code{break-visibility} property controls the visibility of
3321 key signatures and changes of clef only at the start of lines,
3322 i.e. after a break. It has no effect on the visibility of the
3323 key signature or clef following an explicit key change or an
3324 explicit clef change within or at the end of a line. In the
3325 following example the key signature following the explicit change
3326 to B-flat major is still visible, even though @code{all-invisible}
3329 @lilypond[quote,verbatim,relative=1,ragged-right]
3332 % Try to remove all key signatures
3333 \override Staff.KeySignature.break-visibility = #all-invisible
3341 The visibility of such explicit key signature and clef changes is
3342 controlled by the @code{explicitKeySignatureVisibility} and
3343 @code{explicitClefVisibility} properties. These are the equivalent
3344 of the @code{break-visibility} property and both take a vector of
3345 three booleans or the predefined functions listed above, exactly like
3346 @code{break-visibility}. Both are properties of the Staff context,
3347 not the layout objects themselves, and so they are set using the
3348 @code{\set} command. Both are set by default to @code{all-visible}.
3349 These properties control only the visibility of key signatures and
3350 clefs resulting from explicit changes and do not affect key
3351 signatures and clefs at the beginning of lines;
3352 @code{break-visibility} must still be overridden in the appropriate
3353 object to remove these.
3355 @lilypond[quote,verbatim,relative=1,ragged-right]
3358 \set Staff.explicitKeySignatureVisibility = #all-invisible
3359 \override Staff.KeySignature.break-visibility = #all-invisible
3366 @subsubsubheading Visibility of cancelling accidentals
3368 To remove the cancelling accidentals printed at an explicit key
3369 change, set the Staff context property @code{printKeyCancellation}
3372 @lilypond[quote,verbatim,relative=1,ragged-right]
3375 \set Staff.explicitKeySignatureVisibility = #all-invisible
3376 \set Staff.printKeyCancellation = ##f
3377 \override Staff.KeySignature.break-visibility = #all-invisible
3384 With these overrides only the accidentals before the notes remain
3385 to indicate the change of key.
3387 Note that when changing the key to C@tie{}major or A@tie{}minor
3388 the cancelling accidentals would be the @emph{only} indication of
3389 the key change. In this case setting @code{printKeyCancellation} to
3390 @code{#f} has no effect:
3392 @lilypond[quote,verbatim,relative=1,ragged-right]
3395 \set Staff.explicitKeySignatureVisibility = #all-invisible
3396 \set Staff.printKeyCancellation = ##f
3403 To suppress the cancelling accidentals even when the key is
3404 changed to C@tie{}major or A@tie{}minor, override
3405 the visibility of the @code{KeyCancellation} grob instead:
3407 @lilypond[quote,verbatim,relative=1,ragged-right]
3410 \set Staff.explicitKeySignatureVisibility = #all-invisible
3411 \override Staff.KeyCancellation.break-visibility = #all-invisible
3418 @c TODO Add visibility of cautionary accidentals before notes
3420 @subsubsubheading Automatic bars
3422 @cindex automaticBars
3423 @cindex bar lines, suppressing
3425 As a special case, the printing of bar lines can also be turned off
3426 by setting the @code{automaticBars} property in the Score context.
3427 If set to @code{#f}, bar lines will not be printed automatically;
3428 they must be explicitly created with a @code{\bar} command. Unlike
3429 the @code{\cadenzaOn} predefined command, measures are still counted.
3430 Bar generation will resume according to that count if this property
3431 is later set to @code{#t}. When set to @code{#f}, line breaks can
3432 occur only at explicit @code{\bar} commands.
3436 @subsubsubheading Transposed clefs
3438 @cindex transposed clefs, visibility of
3439 @cindex visibility of transposed clefs
3440 @cindex clefs, visibility of transposition
3442 The small transposition symbol on transposed clefs is produced by the
3443 @code{ClefModifier} layout object. Its visibility is automatically
3444 inherited from the @code{Clef} object, so it is not necessary to apply
3445 any required @code{break-visibility} overrides to the @code{ClefModifier}
3446 layout objects to suppress transposition symbols for invisible clefs.
3448 For explicit clef changes, the @code{explicitClefVisibility}
3449 property controls both the clef symbol and any transposition symbol
3454 @rlearning{Visibility and color of objects}.
3458 @subsection Line styles
3460 Some performance indications, e.g., @i{rallentando} and
3461 @i{accelerando} and @i{trills} are written as text and are
3462 extended over many measures with lines, sometimes dotted or wavy.
3464 These all use the same routines as the glissando for drawing the
3465 texts and the lines, and tuning their behavior is therefore also
3466 done in the same way. It is done with a spanner, and the routine
3467 responsible for drawing the spanners is
3468 @code{ly:line-interface::print}. This routine determines the
3469 exact location of the two @i{span points} and draws a line
3470 between them, in the style requested.
3472 Here is an example showing the different line styles available,
3473 and how to tune them.
3475 @lilypond[relative=2,ragged-right,verbatim,quote]
3477 \once \override Glissando.style = #'dashed-line
3479 \override Glissando.style = #'dotted-line
3481 \override Glissando.style = #'zigzag
3483 \override Glissando.style = #'trill
3487 The locations of the end-points of the spanner are computed
3488 on-the-fly for every graphic object, but it is possible to
3492 @lilypond[relative=2,ragged-right,verbatim,quote]
3494 \once \override Glissando.bound-details.right.Y = #-2
3498 The value for @code{Y} is set to @w{@code{-2}} for the right end
3499 point. The left side may be similarly adjusted by specifying
3500 @code{left} instead of @code{right}.
3502 If @code{Y} is not set, the value is computed from the vertical
3503 position of the left and right attachment points of the spanner.
3505 Other adjustments of spanners are possible, for details, see
3508 @node Rotating objects
3509 @subsection Rotating objects
3511 Both layout objects and elements of markup text can be rotated by
3512 any angle about any point, but the method of doing so differs.
3515 * Rotating layout objects::
3519 @node Rotating layout objects
3520 @unnumberedsubsubsec Rotating layout objects
3522 @cindex rotating objects
3523 @cindex objects, rotating
3525 All layout objects which support the @code{grob-interface} can be
3526 rotated by setting their @code{rotation} property. This takes a
3527 list of three items: the angle of rotation counter-clockwise,
3528 and the x and y coordinates of the point relative to the object's
3529 reference point about which the rotation is to be performed. The
3530 angle of rotation is specified in degrees and the coordinates in
3533 The angle of rotation and the coordinates of the rotation point must
3534 be determined by trial and error.
3536 @cindex hairpins, angled
3537 @cindex angled hairpins
3539 There are only a few situations where the rotation of layout
3540 objects is useful; the following example shows one situation where
3543 @lilypond[quote,verbatim,relative=1]
3545 \override Hairpin.rotation = #'(20 -1 0)
3549 @node Rotating markup
3550 @unnumberedsubsubsec Rotating markup
3552 All markup text can be rotated to lie at any angle by prefixing it
3553 with the @code{\rotate} command. The command takes two arguments:
3554 the angle of rotation in degrees counter-clockwise and the text to
3555 be rotated. The extents of the text are not rotated: they take
3556 their values from the extremes of the x and y coordinates of the
3557 rotated text. In the following example the
3558 @code{outside-staff-priority} property for text is set to @code{#f}
3559 to disable the automatic collision avoidance, which would push some
3560 of the text too high.
3562 @lilypond[quote,verbatim,relative=1]
3563 \override TextScript.outside-staff-priority = ##f
3564 g4^\markup { \rotate #30 "a G" }
3565 b^\markup { \rotate #30 "a B" }
3566 des^\markup { \rotate #30 "a D-Flat" }
3567 fis^\markup { \rotate #30 "an F-Sharp" }
3570 @node Advanced tweaks
3571 @section Advanced tweaks
3573 This section discusses various approaches to fine tuning the
3574 appearance of the printed score.
3577 * Aligning objects::
3578 * Vertical grouping of grobs::
3579 * Modifying stencils::
3580 * Modifying shapes::
3581 * Unpure-pure containers::
3586 @rlearning{Tweaking output},
3587 @rlearning{Other sources of information}.
3590 @ref{Explaining the Internals Reference},
3591 @ref{Modifying properties}.
3594 @rextend{Interfaces for programmers}.
3597 @file{scm/define-grobs.scm}.
3600 @rlsr{Tweaks and overrides}.
3602 Internals Reference:
3603 @rinternals{All layout objects}.
3606 @node Aligning objects
3607 @subsection Aligning objects
3609 Graphical objects which support the @code{self-alignment-interface}
3610 and/or the @code{side-position-interface} can be aligned to a previously
3611 placed object in a variety of ways. For a list of these objects, see
3612 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3614 All graphical objects have a reference point, a horizontal extent and a
3615 vertical extent. The horizontal extent is a pair of numbers
3616 giving the displacements from the reference point of the left and
3617 right edges, displacements to the left being negative. The vertical
3618 extent is a pair of numbers giving the displacement from the reference
3619 point to the bottom and top edges, displacements down being negative.
3621 An object's position on a staff is given by the values of the
3622 @code{X-offset} and @code{Y-offset} properties. The value of
3623 @code{X-offset} gives the displacement from the X coordinate of
3624 the reference point of the parent object, and the value of
3625 @code{Y-offset} gives the displacement from the center line of the
3626 staff. The values of @code{X-offset} and @code{Y-offset} may
3627 be set directly or may be set to be calculated by procedures in order
3628 to achieve alignment with the parent object.
3630 @warning{Many objects have special positioning considerations which
3631 cause any setting of @code{X-offset} or @code{Y-offset} to be
3632 ignored or modified, even though the object supports the
3633 @code{self-alignment-interface}. Overriding the @code{X-offset}
3634 or @code{Y-offset} properties to a fixed value causes the respective
3635 @code{self-alignment} property to be disregarded.}
3637 For example, an accidental can be repositioned vertically by setting
3638 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3640 Rehearsal marks may be aligned with breakable objects such as bar
3641 lines, clef symbols, time signature symbols and key signatures. There
3642 are special properties to be found in the @code{break-aligned-interface}
3643 for positioning rehearsal marks on such objects.
3647 @ref{Using the break-alignable-interface}.
3650 @rextend{Callback functions}.
3653 * Setting X-offset and Y-offset directly::
3654 * Using the side-position-interface::
3655 * Using the self-alignment-interface::
3656 * Using the break-alignable-interface::
3659 @node Setting X-offset and Y-offset directly
3660 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3662 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3663 properties of many objects. The following example shows three
3664 notes with the default fingering position and the positions with @code{X-offset}
3665 and @code{Y-offset} modified.
3667 @lilypond[verbatim,quote,relative=2]
3674 -\tweak X-offset #-1
3681 @node Using the side-position-interface
3682 @unnumberedsubsubsec Using the @code{side-position-interface}
3684 An object which supports the @code{side-position-interface} can be
3685 placed next to its parent object so that
3686 the specified edges of the two objects touch. The object may be
3687 placed above, below, to the right or to the left of the parent.
3688 The parent cannot be specified; it is determined by the order of
3689 elements in the input stream. Most objects have the associated
3690 note head as their parent.
3692 The values of the @code{side-axis} and @code{direction} properties
3693 determine where the object is to be placed, as follows:
3695 @c TODO add an example of each to the table
3697 @multitable @columnfractions .3 .3 .3
3698 @headitem @code{side-axis} @tab @code{direction} @tab
3699 @headitem property @tab property @tab Placement
3701 @item @code{0} @tab @code{-1} @tab left
3702 @item @code{0} @tab @code{1} @tab right
3703 @item @code{1} @tab @code{-1} @tab below
3704 @item @code{1} @tab @code{1} @tab above
3708 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3709 the procedure @code{ly:side-position-interface::x-aligned-side}.
3710 This procedure will return the correct value of @code{X-offset} to
3711 place the object to the left or right side of the parent according
3712 to value of @code{direction}.
3714 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3715 the procedure @code{ly:side-position-interface::y-aligned-side}.
3716 This procedure will return the correct value of @code{Y-offset} to
3717 place the object to the top or bottom of the parent according
3718 to value of @code{direction}.
3720 @c TODO Add examples
3722 @node Using the self-alignment-interface
3723 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3725 @subsubsubheading Self-aligning objects horizontally
3727 The horizontal alignment of an object which supports the
3728 @code{self-alignment-interface} is controlled by the value of
3729 the @code{self-alignment-X} property, provided the object's
3730 @code{X-offset} property is set to
3731 @code{ly:self-alignment-interface::x-aligned-on-self}.
3732 @code{self-alignment-X} may be given any
3733 real value, in units of half the total X extent of the
3734 object. Negative values move the object to the right, positive
3735 to the left. A value of @code{0} centers the object on the
3736 reference point of its parent, a value of @w{@code{-1}} aligns the
3737 left edge of the object on the reference point of its parent,
3738 and a value of @code{1} aligns the right edge of the object on the
3739 reference point of its parent. The symbols @code{LEFT},
3740 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3741 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3743 Normally the @code{\override} command would be used to modify the
3744 value of @code{self-alignment-X}, but the @code{\tweak} command
3745 can be used to separately align several annotations on a single
3748 @lilypond[quote,verbatim,relative=1]
3750 -\tweak self-alignment-X #-1
3752 -\tweak self-alignment-X #0
3754 -\tweak self-alignment-X #RIGHT
3756 -\tweak self-alignment-X #-2.5
3757 ^"aligned further to the right"
3760 @subsubsubheading Self-aligning objects vertically
3762 Objects may be aligned vertically in an analogous way to aligning
3763 them horizontally if the @code{Y-offset} property is set to
3764 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3765 other mechanisms are often involved in vertical alignment: the
3766 value of @code{Y-offset} is just one variable taken into account.
3767 This may make adjusting the value of some objects tricky.
3768 The units are just half the vertical extent of the object, which
3769 is usually quite small, so quite large numbers may be required.
3770 A value of @w{@code{-1}} aligns the lower edge of the object with
3771 the reference point of the parent object, a value of @code{0}
3772 aligns the center of the object with the reference point of the
3773 parent, and a value of @code{1} aligns the top edge of the object
3774 with the reference point of the parent. The symbols @code{DOWN},
3775 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3776 @code{0}, and @code{1}, respectively.
3778 @subsubsubheading Self-aligning objects in both directions
3780 By setting both @code{X-offset} and @code{Y-offset}, an object may
3781 be aligned in both directions simultaneously.
3783 The following example shows how to adjust a fingering mark so
3784 that it nestles close to the note head.
3786 @lilypond[quote,verbatim,relative=2]
3788 -\tweak self-alignment-X #0.5 % move horizontally left
3789 -\tweak Y-offset #ly:self-alignment-interface::y-aligned-on-self
3790 -\tweak self-alignment-Y #-1 % move vertically up
3795 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3797 @c Cannot document as they do not seem to operate consistently on all objects -td
3798 @c TODO investigate further
3800 The @code{aligned-on-parent} procedures are used in the same way
3801 as the @code{aligned-on-self} procedures, they difference being
3802 that they permit an object to be aligned with the @emph{edges} of
3803 the parent rather than the parent's reference point. The following
3804 example shows the difference:
3808 @lilypond[verbatim,quote]
3814 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3816 @c Cannot document as they do not seem to operate consistently on all objects -td
3817 @c TODO investigate further
3821 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3823 @node Using the break-alignable-interface
3824 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3826 @cindex align to objects
3827 @cindex break-align-symbols
3829 Rehearsal marks and bar numbers may be aligned with notation
3830 objects other than bar lines. These objects include @code{ambitus},
3831 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3832 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3833 @code{time-signature}.
3835 Each type of object has its own default reference point, to which
3836 rehearsal marks are aligned:
3838 @lilypond[verbatim,quote,relative=1]
3839 % The rehearsal mark will be aligned to right edge of the Clef
3840 \override Score.RehearsalMark.break-align-symbols = #'(clef)
3845 % The rehearsal mark will be centered above the Time Signature
3846 \override Score.RehearsalMark.break-align-symbols = #'(time-signature)
3852 % The rehearsal mark will be centered above the Breath Mark
3853 \override Score.RehearsalMark.break-align-symbols = #'(breathing-sign)
3862 A list of possible target alignment objects may be specified. If
3863 some of the objects are invisible at that point due to the setting
3864 of @code{break-visibility} or the explicit visibility settings for
3865 keys and clefs, the rehearsal mark or bar number is aligned to the
3866 first object in the list which is visible. If no objects in the
3867 list are visible the object is aligned to the bar line. If the bar
3868 line is invisible the object is aligned to the place where the bar
3871 @lilypond[verbatim,quote,relative=1]
3872 % The rehearsal mark will be aligned to the right edge of the Key Signature
3873 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3878 % The rehearsal mark will be aligned to the right edge of the Clef
3879 \set Staff.explicitKeySignatureVisibility = #all-invisible
3880 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3885 % The rehearsal mark will be centered above the Bar Line
3886 \set Staff.explicitKeySignatureVisibility = #all-invisible
3887 \set Staff.explicitClefVisibility = #all-invisible
3888 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3895 The alignment of the rehearsal mark relative to the notation object
3896 can be changed, as shown in the following example. In a score with
3897 multiple staves, this setting should be done for all the staves.
3899 @lilypond[verbatim,quote,relative=1]
3900 % The RehearsalMark will be aligned with the right edge of the Key Signature
3901 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
3907 % The RehearsalMark will be centered above the Key Signature
3908 \once \override Score.KeySignature.break-align-anchor-alignment = #CENTER
3912 % The RehearsalMark will be aligned with the left edge of the Key Signature
3913 \once \override Score.KeySignature.break-align-anchor-alignment = #LEFT
3919 The rehearsal mark can also be offset to the right or left of the left
3920 edge by an arbitrary amount. The units are staff-spaces:
3922 @lilypond[verbatim,quote,relative=1]
3923 % The RehearsalMark will be aligned with the left edge of the Key Signature
3924 % and then shifted right by 3.5 staff-spaces
3925 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
3926 \once \override Score.KeySignature.break-align-anchor = #3.5
3930 % The RehearsalMark will be aligned with the left edge of the Key Signature
3931 % and then shifted left by 2 staff-spaces
3932 \once \override Score.KeySignature.break-align-anchor = #-2
3939 @node Vertical grouping of grobs
3940 @subsection Vertical grouping of grobs
3942 @c TODO Expand this section
3944 The VerticalAlignment and VerticalAxisGroup grobs work together.
3945 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3946 etc. VerticalAlignment then vertically aligns the different grobs
3947 grouped together by VerticalAxisGroup. There is usually only one
3948 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3952 @node Modifying stencils
3953 @subsection Modifying stencils
3955 All layout objects have a @code{stencil} property which is part of
3956 the @code{grob-interface}. By default, this property is usually
3957 set to a function specific to the object that is tailor-made to
3958 render the symbol which represents it in the output. For example,
3959 the standard setting for the @code{stencil} property of the
3960 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3962 The standard symbol for any object can be replaced by modifying the
3963 @code{stencil} property to reference a different, specially-written,
3964 procedure. This requires a high level of knowledge of the internal
3965 workings of LilyPond, but there is an easier way which can often
3966 produce adequate results.
3968 This is to set the @code{stencil} property to the procedure which
3969 prints text -- @code{ly:text-interface::print} -- and to add a
3970 @code{text} property to the object which is set to contain the
3971 markup text which produces the required symbol. Due to the
3972 flexibility of markup, much can be achieved -- see in particular
3973 @ref{Graphic notation inside markup}.
3975 The following example demonstrates this by changing the note head
3976 symbol to a cross within a circle.
3978 @lilypond[verbatim,quote]
3980 \once \override NoteHead.stencil = #ly:text-interface::print
3981 \once \override NoteHead.text = \markup {
3983 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3984 \musicglyph #"noteheads.s2cross"
3992 Any of the glyphs in the feta Font can be supplied to the
3993 @code{\musicglyph} markup command -- see @ref{The Feta font}.
3995 @c TODO Add inserting eps files or ref to later
3997 @c TODO Add inserting Postscript or ref to later
4001 @ref{Graphic notation inside markup},
4002 @ref{Formatting text},
4003 @ref{Text markup commands},
4004 @ref{The Feta font}.
4007 @node Modifying shapes
4008 @subsection Modifying shapes
4011 * Modifying ties and slurs::
4014 @node Modifying ties and slurs
4015 @unnumberedsubsubsec Modifying ties and slurs
4017 @cindex slurs, modifying
4018 @cindex ties, modifying
4019 @cindex Bézier curves, control points
4020 @cindex control points, Bézier curves
4022 @code{Tie}s, @code{Slur}s, @code{PhrasingSlur}s,
4023 @code{LaissezVibrerTie}s and @code{RepeatTie}s are all drawn as
4024 third-order Bézier curves. If the shape of the tie or slur which
4025 is calculated automatically is not optimum, the shape may be
4026 modified manually in two ways:
4030 by specifying the displacements to be made to the control points
4031 of the automatically calculated Bézier curve, or
4034 by explicitly specifying the positions of the four control points
4035 required to define the wanted curve.
4038 Both methods are explained below. The first method is more suitable
4039 if only slight adjustments to the curve are required; the second may
4040 be better for creating curves which are related to just a single
4043 @subsubsubheading Cubic Bézier curves
4045 Third-order or cubic Bézier curves are defined by four control
4046 points. The first and fourth control points are precisely the
4047 starting and ending points of the curve. The intermediate two
4048 control points define the shape. Animations showing how the curve
4049 is drawn can be found on the web, but the following description
4050 may be helpful. The curve starts from the first control point
4051 heading directly towards the second, gradually bending over to
4052 head towards the third and continuing to bend over to head towards
4053 the fourth, arriving there travelling directly from the third
4054 control point. The curve is entirely contained in the
4055 quadrilateral defined by the four control points. Translations,
4056 rotations and scaling of the control points all result in exactly
4057 the same operations on the curve.
4059 @subsubsubheading Specifying displacements from current control points
4061 @cindex shaping slurs and ties
4064 In this example the automatic placement of the tie is not optimum,
4065 and @code{\tieDown} would not help.
4067 @lilypond[verbatim,quote,relative=1]
4071 { r4 <g c,> <g c,> <g c,> }
4075 Adjusting the control points of the tie with @code{\shape} allows
4076 the collisions to be avoided.
4078 The syntax of @code{\shape} is
4081 [-]@code{\shape} @var{displacements} @var{item}
4084 This will reposition the control-points of @var{item} by the amounts
4085 given by @var{displacements}. The @var{displacements} argument is a
4086 list of number pairs or a list of such lists. Each element of a pair
4087 represents the displacement of one of the coordinates of a
4088 control-point. If @var{item} is a string, the result is
4089 @code{\once\override} for the specified grob type. If @var{item} is
4090 a music expression, the result is the same music expression with an
4091 appropriate tweak applied.
4093 In other words, the @code{\shape} function can act as either a
4094 @code{\once\override} command or a @code{\tweak} command depending
4095 on whether the @var{item} argument is a grob name, like @qq{Slur},
4096 or a music expression, like @qq{(}. The @var{displacements} argument
4097 specifies the displacements of the four control points as a list of
4098 four pairs of (dx . dy) values in units of staff-spaces (or a list
4099 of such lists if the curve has more than one segment).
4101 The leading hyphen is required if and only if the @code{\tweak} form
4104 So, using the same example as above and the @code{\once\override}
4105 form of @code{\shape}, this will raise the tie by half a staff-space:
4107 @lilypond[verbatim,quote,relative=1]
4110 \shape #'((0 . 0.5) (0 . 0.5) (0 . 0.5) (0 . 0.5)) Tie
4114 { r4 <g c,> <g c,> <g c,> }
4118 This positioning of the tie is better, but maybe it should be raised
4119 more in the center. The following example does this, this time using
4120 the alternative @code{\tweak} form:
4122 @lilypond[verbatim,quote,relative=1]
4125 e1-\shape #'((0 . 0.5) (0 . 1) (0 . 1) (0 . 0.5)) ~ e
4128 { r4 <g c,> <g c,> <g c,> }
4132 Changes to the horizontal positions of the control points may be made
4133 in the same way, and two different curves starting at the same
4134 musical moment may also be shaped:
4136 @lilypond[verbatim,quote,ragged-right,relative=2]
4138 \shape #'((0.7 . -0.4) (0.5 . -0.4) (0.3 . -0.3) (0 . -0.2)) Slur
4139 \shape #'((0 . 0) (0 . 0.5) (0 . 0.5) (0 . 0)) PhrasingSlur
4143 The @code{\shape} function can also displace the control points of
4144 curves which stretch across line breaks. Each piece of the broken
4145 curve can be given its own list of offsets. If changes to a
4146 particular segment are not needed, the empty list can serve as a
4147 placeholder. In this example the line break makes the single slur
4150 @lilypond[verbatim,quote,ragged-right,relative=1]
4156 Changing the shapes of the two halves of the slur makes it clearer
4157 that the slur continues over the line break:
4159 @lilypond[verbatim,quote,ragged-right,relative=1]
4160 % () may be used as a shorthand for ((0 . 0) (0 . 0) (0 . 0) (0 . 0))
4161 % if any of the segments does not need to be changed
4163 (( 0 . 0) (0 . 0) (0 . 0) (0 . 1))
4164 ((0.5 . 1.5) (1 . 0) (0 . 0) (0 . -1.5))
4171 If an S-shaped curve is required the control points must always be
4172 adjusted manually --- LilyPond will never select such shapes
4175 @lilypond[verbatim,quote,relative=2]
4176 c8( e b-> f d' a e-> g)
4177 \shape #'((0 . -1) (5.5 . -0.5) (-5.5 . -10.5) (0 . -5.5)) PhrasingSlur
4178 c8\( e b-> f d' a e-> g\)
4181 @subsubsubheading Specifying control points explicitly
4183 The coordinates of the Bézier control points are specified in units
4184 of staff-spaces. The X@tie{}coordinate is relative to the reference
4185 point of the note to which the tie or slur is attached, and the
4186 Y@tie{}coordinate is relative to the staff center line. The
4187 coordinates are specified as a list of four pairs of decimal numbers
4188 (reals). One approach is to estimate the coordinates of the two
4189 end points, and then guess the two intermediate points. The optimum
4190 values are then found by trial and error. Be aware that these values
4191 may need to be manually adjusted if any further changes are made to
4192 the music or the layout.
4194 One situation where specifying the control points explicitly is
4195 preferable to specifying displacements is when they need to be
4196 specified relative to a single note. Here is an example of this.
4197 It shows one way of indicating a slur extending into alternative
4198 sections of a volta repeat.
4200 @lilypond[verbatim,quote,relative=2]
4202 \repeat volta 3 { c4 d( e f }
4207 % create a slur and move it to a new position
4208 % the <> is just an empty chord to carry the slur termination
4209 -\tweak control-points #'((-2 . 3.8) (-1 . 3.9) (0 . 4) (1 . 3.4)) ( <> )
4214 % create a slur and move it to a new position
4215 -\tweak control-points #'((-2 . 3) (-1 . 3.1) (0 . 3.2) (1 . 2.4)) ( <> )
4222 It is not possible to modify shapes of ties or slurs by changing
4223 the @code{control-points} property if there are multiple ties or slurs
4224 at the same musical moment -- the @code{\tweak} command will also not
4225 work in this case. However, the @code{tie-configuration} property of
4226 @code{TieColumn} can be overridden to set start line and direction as
4230 Internals Reference:
4231 @rinternals{TieColumn}.
4234 @node Unpure-pure containers
4235 @subsection Unpure-pure containers
4237 @cindex Scheme, pure containers
4238 @cindex Scheme, unpure containers
4239 @cindex pure containers, Scheme
4240 @cindex unpure containers, Scheme
4241 @cindex horizontal spacing, overriding
4243 Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
4244 calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
4245 Scheme function instead of a literal (i.e. a number or pair).
4247 For certain grobs, the @code{Y-extent} is based on the @code{stencil}
4248 property, overriding the stencil property of one of these will
4249 require an additional @code{Y-extent} override with an unpure-pure
4250 container. When a function overrides a @code{Y-offset} and/or
4251 @code{Y-extent} it is assumed that this will trigger line breaking
4252 calculations too early during compilation. So the function is not
4253 evaluated at all (usually returning a value of @samp{0} or
4254 @samp{'(0 . 0)}) which can result in collisions. A @q{pure} function
4255 will not affect properties, objects or grob suicides and therefore will
4256 always have its Y-axis-related evaluated correctly.
4258 Currently, there are about thirty functions that are already considered
4259 @q{pure} and Unpure-pure containers are a way to set functions not on
4260 this list as @q{pure}. The @q{pure} function is evaluated @emph{before}
4261 any line-breaking and so the horizontal spacing can be adjusted
4262 @q{in time}. The @q{unpure} function is then evaluated @emph{after}
4265 @warning{As it is difficult to always know which functions are on this
4266 list we recommend that any @q{pure} functions you create do not use
4267 @code{Beam} or @code{VerticalAlignment} grobs.}
4269 An unpure-pure container is constructed as follows;
4271 @code{(ly:make-unpure-pure-container f0 f1)}
4273 where @code{f0} is a function taking @var{n} arguments (@var{n >= 1})
4274 and the first argument must always be the grob. This is the function
4275 that gives the actual result. @var{f1} is the function being labeled
4276 as @q{pure} that takes @var{n + 2} arguments. Again, the first argument
4277 must always still be the grob but the second and third are @q{start}
4278 and @q{end} arguments.
4280 @var{start} and @var{end} are, for all intents and purposes, dummy
4281 values that only matter for @code{Spanners} (i.e @code{Hairpin} or
4282 @code{Beam}), that can return different height estimations based on a
4283 starting and ending column.
4285 The rest are the other arguments to the first function (which
4286 may be none if @var{n = 1}).
4288 The results of the second function are used as an approximation of the
4289 value needed which is then used by the first function to get the real
4290 value which is then used for fine-tuning much later during the spacing
4293 @lilypond[verbatim,quote,ragged-right]
4294 #(define (square-line-circle-space grob)
4295 (let* ((pitch (ly:event-property (ly:grob-property grob 'cause) 'pitch))
4296 (notename (ly:pitch-notename pitch)))
4297 (if (= 0 (modulo notename 2))
4298 (make-circle-stencil 0.5 0.0 #t)
4299 (make-filled-box-stencil '(0 . 1.0)
4302 squareLineCircleSpace = {
4303 \override NoteHead.stencil = #square-line-circle-space
4306 smartSquareLineCircleSpace = {
4307 \squareLineCircleSpace
4308 \override NoteHead.Y-extent =
4309 #(ly:make-unpure-pure-container
4310 ly:grob::stencil-height
4311 (lambda (grob start end) (ly:grob::stencil-height grob)))
4314 \new Voice \with { \remove "Stem_engraver" }
4316 \squareLineCircleSpace
4318 \smartSquareLineCircleSpace
4323 In the first measure, without the unpure-pure container, the spacing
4324 engine does not know the width of the note head and lets it collide with
4325 the accidentals. In the second measure, with unpure-pure containers,
4326 the spacing engine knows the width of the note heads and avoids the
4327 collision by lengthening the line accordingly.
4329 Usually for simple calculations nearly-identical functions for both the
4330 @q{unpure} and @q{pure} parts can be used, by only changing the number
4331 of arguments passed to, and the scope of, the function.
4333 @warning{If a function is labeled as @q{pure} and it turns out not to
4334 be, the results can be unexpected.}
4337 @node Using music functions
4338 @section Using music functions
4340 @c TODO -- add @seealso, etc. to these subsections
4342 Where tweaks need to be reused with different music expressions,
4343 it is often convenient to make the tweak part of a @emph{music
4344 function}. In this section, we discuss only @emph{substitution}
4345 functions, where the object is to substitute a variable into a
4346 piece of LilyPond input code. Other more complex functions are
4347 described in @rextend{Music functions}.
4350 * Substitution function syntax::
4351 * Substitution function examples::
4354 @node Substitution function syntax
4355 @subsection Substitution function syntax
4357 Making a function that substitutes a variable into LilyPond
4358 code is easy. The general form of these functions is
4362 #(define-music-function
4363 (parser location @var{arg1} @var{arg2} @dots{})
4364 (@var{type1?} @var{type2?} @dots{})
4366 @var{@dots{}music@dots{}}
4373 @multitable @columnfractions .33 .66
4374 @item @code{@var{argN}}
4375 @tab @var{n}th argument
4377 @item @code{@var{typeN?}}
4378 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
4379 must return @code{#t}.
4381 @item @code{@var{@dots{}music@dots{}}}
4382 @tab normal LilyPond input, using @code{$} (in places where only
4383 Lilypond constructs are allowed) or @code{#} (to use it as a Scheme
4384 value or music function argument or music inside of music lists) to
4389 The @code{parser} and @code{location} arguments are mandatory, and
4390 are used in some advanced situations as described in the
4391 @q{Extending} manual (see @rextend{Music functions}). For
4392 substitution functions, just be sure to include them.
4394 The list of type predicates is also required. Some of the most
4395 common type predicates used in music functions are:
4399 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
4411 For a list of available type predicates, see
4412 @ref{Predefined type predicates}. User-defined type predicates
4417 @ref{Predefined type predicates}.
4420 @rextend{Music functions}.
4423 @file{lily/music-scheme.cc},
4425 @file{scm/lily.scm}.
4428 @node Substitution function examples
4429 @subsection Substitution function examples
4431 This section introduces some substitution function examples.
4432 These are not intended to be exhaustive, but rather to demonstrate
4433 some of the possibilities of simple substitution functions.
4435 In the first example, a function is defined that simplifies
4436 setting the padding of a TextScript:
4438 @lilypond[quote,verbatim,ragged-right]
4440 #(define-music-function
4441 (parser location padding)
4444 \once \override TextScript.padding = #padding
4448 c4^"piu mosso" b a b
4450 c4^"piu mosso" b a b
4452 c4^"piu mosso" b a b
4456 In addition to numbers, we can use music expressions such
4457 as notes for arguments to music functions:
4459 @lilypond[quote,verbatim,ragged-right]
4461 #(define-music-function
4462 (parser location note)
4465 \tweak NoteHead.stencil #ly:text-interface::print
4466 \tweak NoteHead.text
4467 \markup \musicglyph #"custodes.mensural.u0"
4468 \tweak Stem.stencil ##f
4472 \relative c' { c4 d e f \custosNote g }
4475 Substitution functions with multiple arguments can be defined:
4477 @lilypond[quote,verbatim,ragged-right]
4479 #(define-music-function
4480 (parser location padding tempotext)
4483 \once \override Score.MetronomeMark.padding = #padding
4484 \tempo \markup { \bold #tempotext }
4488 \tempo \markup { "Low tempo" }
4490 \tempoPadded #4.0 "High tempo"
4495 @c TODO: add appropriate @@ref's here.