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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}.
433 @code{\context} with no name will match the first of any previously
434 created contexts of the same type in the same context heirarchy,
435 even one that has been given a name, and its music expression will be
436 passed to that context for interpretation. This form is rarely
437 useful. However, @code{\context} with no name and no music expression
438 is used to set the context in which a Scheme procedure specified with
439 @code{\applyContext} is executed:
442 \new Staff \relative c' @{
445 \applyContext #(lambda (ctx)
447 (display (ly:context-current-moment ctx)))
454 A context must be named if it is to be referenced later, for example
455 when lyrics are associated with music:
458 \new Voice = "tenor" @var{music}
460 \new Lyrics \lyricsto "tenor" @var{lyrics}
464 For details of associating lyrics with music see
465 @ref{Automatic syllable durations}.
467 The properties of all contexts of a particular type can be modified
468 in a @code{\layout} block (with a different syntax), see
469 @ref{Changing all contexts of the same type}. This construct also
470 provides a means of keeping layout instructions separate from the
471 musical content. If a single context is to be modified, a @code{\with}
472 block must be used, see @ref{Changing just one specific context}.
477 @rlearning{Organizing pieces with variables}.
480 @ref{Changing just one specific context},
481 @ref{Automatic syllable durations}.
484 @node Keeping contexts alive
485 @subsection Keeping contexts alive
487 @cindex contexts, keeping alive
488 @cindex contexts, lifetime
490 Contexts are usually terminated at the first musical moment in
491 which they have nothing to do. So @code{Voice} contexts die as
492 soon as they contain no events; @code{Staff} contexts die as soon
493 as all the @code{Voice} contexts within them contain no events; etc.
494 This can cause difficulties if earlier contexts which have died
495 have to be referenced, for example, when changing staves with
496 @code{\change} commands, associating lyrics with a voice with
497 @code{\lyricsto} commands, or when adding further musical events to
500 There is an exception to this general rule: just one of the
501 @code{Voice} contexts in a @code{Staff} context or in a
502 @code{<<@dots{}>>} construct will always persist to the end of the
503 enclosing @code{Staff} context or @code{<<@dots{}>>} construct, even
504 though there may be periods when it has nothing to do. The context
505 to persist in this way will be the first one encountered in the
506 first enclosed @code{@{@dots{}@}} construct, ignoring any in enclosed
507 @code{<<@dots{}>>} constructs.
509 Any context can be kept alive by ensuring it has something to do at
510 every musical moment. @code{Staff} contexts are kept alive by
511 ensuring one of their voices is kept alive. One way of doing this
512 is to add spacer rests to a voice in parallel with the real music.
513 These need to be added to every @code{Voice} context which needs to
514 be kept alive. If several voices are to be used sporadically it is
515 safest to keep them all alive rather than attempting to rely on the
516 exceptions mentioned above.
518 In the following example, both voice A and voice B are kept alive
519 in this way for the duration of the piece:
521 @lilypond[quote,verbatim]
522 musicA = \relative c'' { d4 d d d }
523 musicB = \relative c'' { g4 g g g }
526 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
527 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
532 \context Voice = "A" {
536 \context Voice = "B" {
540 \context Voice = "A" { \musicA }
541 \context Voice = "B" { \musicB }
542 \context Voice = "A" { \musicA }
553 @cindex lyrics, aligning with sporadic melody
555 The following example shows how a sporadic melody line with lyrics
556 might be written using this approach. In a real situation the
557 melody and accompaniment would consist of several different
560 @lilypond[quote,verbatim]
561 melody = \relative c'' { a4 a a a }
562 accompaniment = \relative c' { d4 d d d }
563 words = \lyricmode { These words fol -- low the mel -- o -- dy }
566 \new Staff = "music" {
568 \new Voice = "melody" {
570 s1*4 % Keep Voice "melody" alive for 4 bars
573 \new Voice = "accompaniment" {
578 \context Voice = "melody" { \melody }
579 \context Voice = "accompaniment" { \accompaniment }
581 \context Voice = "accompaniment" { \accompaniment }
583 \context Voice = "melody" { \melody }
584 \context Voice = "accompaniment" { \accompaniment }
589 \new Lyrics \with { alignAboveContext = #"music" }
590 \lyricsto "melody" { \words }
595 An alternative way, which may be better in many circumstances, is
596 to keep the melody line alive by simply including spacer notes to
597 line it up correctly with the accompaniment:
599 @lilypond[quote,verbatim]
600 melody = \relative c'' {
606 accompaniment = \relative c' {
612 words = \lyricmode { These words fol -- low the mel -- o -- dy }
616 \new Staff = "music" {
618 \new Voice = "melody" {
622 \new Voice = "accompaniment" {
628 \new Lyrics \with { alignAboveContext = #"music" }
629 \lyricsto "melody" { \words }
635 @node Modifying context plug-ins
636 @subsection Modifying context plug-ins
638 @c TODO Should this be Modifying engravers or Modifying contexts?
640 Notation contexts (like @code{Score} and @code{Staff}) not only store
641 properties, they also contain plug-ins called @q{engravers} that create
642 notation elements. For example, the @code{Voice} context contains a
643 @code{Note_heads_engraver} and the @code{Staff} context contains a
646 For a full a description of each plug-in, see
648 @rinternals{Engravers and Performers}.
651 Internals Reference @expansion{} Translation @expansion{} Engravers.
653 Every context described in
655 @rinternals{Contexts}
658 Internals Reference @expansion{} Translation @expansion{} Context.
660 lists the engravers used for that context.
663 It can be useful to shuffle around these plug-ins. This is done by
664 starting a new context with @code{\new} or @code{\context}, and
670 \new @var{context} \with @{
678 @emph{@dots{}music@dots{}}
683 where the @dots{} should be the name of an engraver. Here is a simple
684 example which removes @code{Time_signature_engraver} and
685 @code{Clef_engraver} from a @code{Staff} context,
687 @lilypond[quote,relative=1,verbatim]
693 \remove "Time_signature_engraver"
694 \remove "Clef_engraver"
701 In the second staff there are no time signature or clef symbols. This
702 is a rather crude method of making objects disappear since it will affect
703 the entire staff. This method also influences the spacing, which may or
704 may not be desirable. More sophisticated methods of blanking objects
705 are shown in @rlearning{Visibility and color of objects}.
707 The next example shows a practical application. Bar lines and time
708 signatures are normally synchronized across the score. This is done
709 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
710 This plug-in keeps an administration of time signature, location
711 within the measure, etc. By moving these engraver from @code{Score} to
712 @code{Staff} context, we can have a score where each staff has its own
715 @cindex polymetric scores
716 @cindex Time signatures, multiple
718 @lilypond[quote,verbatim]
722 \consists "Timing_translator"
723 \consists "Default_bar_line_engraver"
729 \consists "Timing_translator"
730 \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}
958 [context settings for this context instance only]
964 The following types of settings may be specified:
968 An @code{\override} command, but with the context name omitted
970 @lilypond[quote,verbatim]
975 \override Stem.thickness = #4.0
979 a4^"Thick stems" a a a
988 Directly setting a context property
990 @lilypond[quote,verbatim]
995 a4^"Default font" a a a
1004 a4^"Smaller font" a a a
1013 A predefined command such as @code{\dynamicUp}
1015 @lilypond[quote,verbatim]
1021 a4^"Dynamics below" a a a
1027 \with { \accidentalStyle dodecaphonic }
1030 \with { \dynamicUp }
1033 a4^"Dynamics above" a a a
1044 @node Order of precedence
1045 @unnumberedsubsubsec Order of precedence
1047 The value of a property which applies at a particular time is
1048 determined as follows:
1052 if an @code{\override} or @code{\set} command in the input stream is
1053 in effect that value is used,
1056 otherwise the default value taken from a @code{\with} statement
1057 on the context initiation statement is used,
1060 otherwise the default value taken from the most recent appropriate
1061 @code{\context} block in the @code{\layout} blocks is used,
1064 otherwise the LilyPond built-in default is used.
1069 @rlearning{Modifying context properties}.
1072 @ref{Contexts explained},
1073 @ref{Bottom-level contexts - voices},
1074 @ref{The set command},
1075 @ref{The override command},
1076 @ref{The \layout block}.
1079 @node Defining new contexts
1080 @subsection Defining new contexts
1082 @cindex contexts, defining new
1083 @cindex engravers, including in contexts
1098 Specific contexts, like @code{Staff} and @code{Voice}, are made from
1099 simple building blocks. It is possible to create new types of
1100 contexts with different combinations of engraver plug-ins.
1102 The next example shows how to build a different type of
1103 @code{Voice} context from scratch. It will be similar to
1104 @code{Voice}, but only prints centered slash note heads. It can be used
1105 to indicate improvisation in jazz pieces,
1107 @lilypond[quote,ragged-right]
1108 \layout { \context {
1110 \type "Engraver_group"
1111 \consists "Note_heads_engraver"
1112 \consists "Rhythmic_column_engraver"
1113 \consists "Text_engraver"
1114 \consists "Pitch_squash_engraver"
1115 squashedPosition = #0
1116 \override NoteHead.style = #'slash
1117 \override Stem.transparent = ##t
1121 \accepts "ImproVoice"
1125 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1126 c4 c^"undress" c_"while playing :)" c }
1132 These settings are defined within a @code{\context} block inside a
1133 @code{\layout} block,
1143 In the following discussion, the example input shown should go in place
1144 of the @dots{} in the previous fragment.
1146 First it is necessary to define a name for the new context:
1152 Since it is similar to the @code{Voice} context, we want commands that
1153 work in (existing) @code{Voice} contexts to continue working. This is
1154 achieved by giving the new context an alias of @code{Voice},
1160 The context will print notes and instructive texts, so we need to add
1161 the engravers which provide this functionality, plus the engraver which
1162 groups notes, stems and rests which occur at the same musical moment
1166 \consists "Note_heads_engraver"
1167 \consists "Text_engraver"
1168 \consists "Rhythmic_column_engraver"
1171 The note heads should all be placed on the center line,
1174 \consists "Pitch_squash_engraver"
1175 squashedPosition = #0
1178 The @code{Pitch_squash_engraver} modifies note heads (created
1179 by the @code{Note_heads_engraver}) and sets their vertical
1180 position to the value of @code{squashedPosition}, in this
1181 case@tie{}@code{0}, the center line.
1183 The notes look like a slash, and have no stem,
1186 \override NoteHead.style = #'slash
1187 \override Stem.transparent = ##t
1190 All these plug-ins have to cooperate, and this is achieved with a
1191 special plug-in, which must be marked with the keyword @code{\type}.
1192 This should always be @code{Engraver_group}.
1195 \type "Engraver_group"
1198 Put together, we get
1203 \type "Engraver_group"
1204 \consists "Note_heads_engraver"
1205 \consists "Text_engraver"
1206 \consists "Rhythmic_column_engraver"
1207 \consists "Pitch_squash_engraver"
1208 squashedPosition = #0
1209 \override NoteHead.style = #'slash
1210 \override Stem.transparent = ##t
1216 Contexts form hierarchies. We want to place the @code{ImproVoice}
1217 context within the @code{Staff} context, just like normal @code{Voice}
1218 contexts. Therefore, we modify the @code{Staff} definition with the
1219 @code{\accepts} command,
1229 The opposite of @code{\accepts} is @code{\denies},
1230 which is sometimes needed when reusing existing context definitions.
1232 Putting both into a @code{\layout} block, like
1242 \accepts "ImproVoice"
1247 Then the output at the start of this subsection can be entered as
1255 c c_"while playing :)"
1263 Internals Reference:
1264 @rinternals{Engraver_group},
1265 @rinternals{Note_heads_engraver},
1266 @rinternals{Text_engraver},
1267 @rinternals{Rhythmic_column_engraver},
1268 @rinternals{Pitch_squash_engraver}.
1271 @node Context layout order
1272 @subsection Context layout order
1274 @cindex contexts, layout order
1278 Contexts are normally positioned in a system from top to bottom
1279 in the order in which they are encountered in the input file. When
1280 contexts are nested, the outer context will include inner nested
1281 contexts as specified in the input file, provided the inner contexts
1282 are included in the outer context's @qq{accepts} list. Nested
1283 contexts which are not included in the outer context's @qq{accepts}
1284 list will be repositioned below the outer context rather than nested
1287 The @qq{accepts} list of a context can be changed with the
1288 @code{\accepts} and @code{\denies} commands. @code{\accepts} adds a
1289 context to the @qq{accepts} list and @code{\denies} removes a context
1290 from the list. For example, it would not normally be desirable for
1291 chord names to be nested within a @code{Staff} context, so the
1292 @code{ChordNames} context is not included by default in the @qq{accepts}
1293 list of the @code{Staff} context, but if this were to be required it can
1296 @lilypond[verbatim,quote]
1300 \chords { d1:m7 b1:min7.5- }
1305 @lilypond[verbatim,quote]
1309 \chords { d1:m7 b1:min7.5- }
1314 \accepts "ChordNames"
1320 @code{\denies} is mainly used when a new context is being based on
1321 another, but the required nesting differs. For example, the
1322 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1323 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1324 context in the @qq{accepts} list.
1326 @cindex contexts, implicit
1327 @cindex implicit contexts
1328 @funindex \defaultchild
1330 Note that a context will be silently created implicitly if a
1331 command is encountered when there is no suitable context available
1334 Within a context definition, the type of subcontext to be
1335 implicitly created is specified using @code{\defaultchild}. A
1336 number of music events require a @samp{Bottom} context: when such
1337 an event is encountered, subcontexts are created recursively until
1338 reaching a context with no @samp{defaultchild} setting.
1340 Implicit context creation can at times give rise to unexpected new
1341 staves or scores. Using @code{\new} to create contexts explicitly
1342 avoids those problems.
1344 @cindex alignAboveContext
1345 @cindex alignBelowContext
1346 @funindex alignAboveContext
1347 @funindex alignBelowContext
1349 Sometimes a context is required to exist for just a brief period, a
1350 good example being the staff context for an ossia. This is usually
1351 achieved by introducing the context definition at the appropriate
1352 place in parallel with corresponding section of the main music.
1353 By default, the temporary context will be placed below all the
1354 existing contexts. To reposition it above the context called
1355 @qq{main}, it should be defined like this:
1358 @code{\new Staff \with @{ alignAboveContext = #"main" @} }
1361 A similar situation arises when positioning a temporary lyrics
1362 context within a multi-staved layout such as a @code{ChoirStaff},
1363 for example, when adding a second verse to a repeated section.
1364 By default the temporary lyrics context will be placed beneath the
1365 lower staves. By defining the temporary lyrics context with
1366 @code{alignBelowContext} it can be positioned correctly beneath
1367 the (named) lyrics context containing the first verse.
1369 Examples showing this repositioning of temporary contexts can be
1370 found elsewhere --- see @rlearning{Nesting music expressions},
1371 @ref{Modifying single staves} and @ref{Techniques specific to lyrics}.
1375 @rlearning{Nesting music expressions}.
1378 @ref{Modifying single staves},
1379 @ref{Techniques specific to lyrics}.
1382 @rprogram{An extra staff appears}.
1385 @file{ly/engraver-init.ly}.
1388 @node Explaining the Internals Reference
1389 @section Explaining the Internals Reference
1392 * Navigating the program reference::
1393 * Layout interfaces::
1394 * Determining the grob property::
1395 * Naming conventions::
1398 @node Navigating the program reference
1399 @subsection Navigating the program reference
1401 @c TODO remove this (it's in the LM)
1402 @c Replace with more factual directions
1404 Suppose we want to move the fingering indication in the fragment
1407 @lilypond[quote,relative=2,verbatim]
1413 If you visit the documentation on fingering instructions (in
1414 @ref{Fingering instructions}), you will notice:
1419 Internals Reference: @rinternals{Fingering}.
1424 @c outdated info; probably will delete.
1426 This fragment points to two parts of the program reference: a page
1427 on @code{FingeringEvent} and one on @code{Fingering}.
1429 The page on @code{FingeringEvent} describes the properties of the music
1430 expression for the input @w{@code{-2}}. The page contains many links
1431 forward. For example, it says
1434 Accepted by: @rinternals{Fingering_engraver},
1438 That link brings us to the documentation for the Engraver, the
1442 This engraver creates the following layout objects: @rinternals{Fingering}.
1445 In other words, once the @code{FingeringEvent}s are interpreted, the
1446 @code{Fingering_engraver} plug-in will process them.
1450 @c I can't figure out what this is supposed to mean. -gp
1452 The @code{Fingering_engraver} is also listed to create
1453 @rinternals{Fingering} objects,
1455 @c old info? it doesn't make any sense to me with our current docs.
1457 second bit of information listed under @b{See also} in the Notation
1462 The programmer's reference is available as an HTML document. It is
1463 highly recommended that you read it in HTML form, either online or
1464 by downloading the HTML documentation. This section will be much more
1465 difficult to understand if you are using the
1469 Follow the link to @rinternals{Fingering}. At the top of the
1473 Fingering objects are created by: @rinternals{Fingering_engraver} and
1474 @rinternals{New_fingering_engraver}.
1477 By following related links inside the program reference, we can follow the
1478 flow of information within the program:
1482 @item @rinternals{Fingering}:
1483 @rinternals{Fingering} objects are created by:
1484 @rinternals{Fingering_engraver}
1486 @item @rinternals{Fingering_engraver}:
1487 Music types accepted: @rinternals{fingering-event}
1489 @item @rinternals{fingering-event}:
1490 Music event type @code{fingering-event} is in Music expressions named
1491 @rinternals{FingeringEvent}
1494 This path goes against the flow of information in the program: it
1495 starts from the output, and ends at the input event. You could
1496 also start at an input event, and read with the flow of
1497 information, eventually ending up at the output object(s).
1499 The program reference can also be browsed like a normal document. It
1500 contains chapters on
1502 @rinternals{Music definitions},
1505 @code{Music definitions}
1507 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1508 chapter lists all the definitions used and all properties that may be
1512 @node Layout interfaces
1513 @subsection Layout interfaces
1515 @cindex interface, layout
1516 @cindex layout interface
1519 The HTML page that we found in the previous section describes the
1520 layout object called @rinternals{Fingering}. Such an object is a
1521 symbol within the score. It has properties that store numbers (like
1522 thicknesses and directions), but also pointers to related objects. A
1523 layout object is also called a @emph{Grob}, which is short for Graphical
1524 Object. For more details about Grobs, see @rinternals{grob-interface}.
1526 The page for @code{Fingering} lists the definitions for the
1527 @code{Fingering} object. For example, the page says
1530 @code{padding} (dimension, in staff space):
1536 which means that the number will be kept at a distance of at least 0.5
1540 Each layout object may have several functions as a notational or
1541 typographical element. For example, the Fingering object
1542 has the following aspects
1546 Its size is independent of the horizontal spacing, unlike slurs or beams.
1549 It is a piece of text. Granted, it is usually a very short text.
1552 That piece of text is typeset with a font, unlike slurs or beams.
1555 Horizontally, the center of the symbol should be aligned to the
1556 center of the note head.
1559 Vertically, the symbol is placed next to the note and the staff.
1562 The vertical position is also coordinated with other superscript
1563 and subscript symbols.
1566 Each of these aspects is captured in so-called @emph{interface}s,
1567 which are listed on the @rinternals{Fingering} page at the bottom
1570 This object supports the following interfaces:
1571 @rinternals{item-interface},
1572 @rinternals{self-alignment-interface},
1573 @rinternals{side-position-interface}, @rinternals{text-interface},
1574 @rinternals{text-script-interface}, @rinternals{font-interface},
1575 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1578 Clicking any of the links will take you to the page of the respective
1579 object interface. Each interface has a number of properties. Some of
1580 them are not user-serviceable (@q{Internal properties}), but others
1583 We have been talking of @emph{the} @code{Fingering} object, but actually it
1584 does not amount to much. The initialization file (see
1585 @rlearning{Other sources of information})
1586 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1591 (avoid-slur . around)
1592 (slur-padding . 0.2)
1593 (staff-padding . 0.5)
1594 (self-alignment-X . 0)
1595 (self-alignment-Y . 0)
1596 (script-priority . 100)
1597 (stencil . ,ly:text-interface::print)
1598 (direction . ,ly:script-interface::calc-direction)
1599 (font-encoding . fetaText)
1600 (font-size . -5) ; don't overlap when next to heads.
1601 (meta . ((class . Item)
1602 (interfaces . (finger-interface
1604 text-script-interface
1606 side-position-interface
1607 self-alignment-interface
1608 item-interface))))))
1612 As you can see, the @code{Fingering} object is nothing more than a
1613 bunch of variable settings, and the webpage in the Internals Reference
1614 is directly generated from this definition.
1617 @node Determining the grob property
1618 @subsection Determining the grob property
1620 @c TODO remove this (it's in the LM)
1621 @c Replace with more factual directions
1623 Recall that we wanted to change the position of the @b{2} in
1625 @lilypond[quote,relative=2,verbatim]
1631 Since the @b{2} is vertically positioned next to its note, we have to
1632 meddle with the interface associated with this positioning. This is
1633 done using @code{side-position-interface}. The page for this interface
1637 @code{side-position-interface}
1639 Position a victim object (this one) next to other objects (the
1640 support). The property @code{direction} signifies where to put the
1641 victim object relative to the support (left or right, up or down?)
1646 Below this description, the variable @code{padding} is described as
1651 (dimension, in staff space)
1653 Add this much extra space between objects that are next to each other.
1657 By increasing the value of @code{padding}, we can move the
1658 fingering away from the note head. The following command inserts
1659 3 staff spaces of white
1660 between the note and the fingering:
1662 \once \override Voice.Fingering.padding = #3
1665 Inserting this command before the Fingering object is created,
1666 i.e., before @code{c2}, yields the following result:
1668 @lilypond[quote,relative=2,verbatim]
1669 \once \override Voice.Fingering.padding = #3
1676 In this case, the context for this tweak is @code{Voice}. This
1677 fact can also be deduced from the program reference, for the page for
1678 the @rinternals{Fingering_engraver} plug-in says
1681 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1685 @node Naming conventions
1686 @subsection Naming conventions
1688 Another thing that is needed, is an overview of the various naming
1692 @item scheme functions: lowercase-with-hyphens (incl. one-word
1694 @item scheme functions: ly:plus-scheme-style
1695 @item music events, music classes and music properties:
1697 @item Grob interfaces: scheme-style
1698 @item backend properties: scheme-style (but X and Y!)
1699 @item contexts (and MusicExpressions and grobs): Capitalized or
1701 @item context properties: lowercaseFollowedByCamelCase
1703 Capitalized_followed_by_lowercase_and_with_underscores
1706 Questions to be answered:
1708 @item Which of these are conventions and which are rules?
1709 @item Which are rules of the underlying language, and which are
1713 @node Modifying properties
1714 @section Modifying properties
1716 @c TODO change the menu and subsection node names to use
1717 @c backslash once the new macro to handle the refs
1718 @c is available. Need to find and change all refs at
1719 @c the same time. -td
1722 * Overview of modifying properties::
1724 * The override command::
1725 * The tweak command::
1726 * set versus override::
1727 * Modifying alists::
1731 @node Overview of modifying properties
1732 @subsection Overview of modifying properties
1734 Each context is responsible for creating certain types of graphical
1735 objects. The settings used for printing these objects are also stored by
1736 context. By changing these settings, the appearance of objects can be
1739 There are two different kinds of properties stored in contexts:
1740 context properties and grob properties. Context properties are
1741 properties that apply to the context as a whole and control
1742 how the context itself is displayed. In contrast, grob properties
1743 apply to specific grob types that will be displayed in the context.
1745 The @code{\set} and @code{\unset} commands are used to change values
1746 for context properties. The @code{\override} and @code{\revert}
1747 commands are used to change values for grob properties.
1750 The syntax for this is
1753 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1756 Here @var{name} is the name of a graphical object, like
1757 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1758 variable of the formatting system (@q{grob property} or @q{layout
1759 property}). The latter is a symbol, so it must be quoted. The
1760 subsection @ref{Modifying properties}, explains what to fill in
1761 for @var{name}, @var{property}, and @var{value}. Here we only
1762 discuss the functionality of this command.
1767 \override Staff.Stem.thickness = #4.0
1771 makes stems thicker (the default is 1.3, with staff line thickness as a
1772 unit). Since the command specifies @code{Staff} as context, it only
1773 applies to the current staff. Other staves will keep their normal
1774 appearance. Here we see the command in action:
1776 @lilypond[quote,verbatim,relative=2]
1778 \override Staff.Stem.thickness = #4.0
1784 The @code{\override} command changes the definition of the @code{Stem}
1785 within the current @code{Staff}. After the command is interpreted
1786 all stems are thickened.
1788 Analogous to @code{\set}, the @var{context} argument may be left out,
1789 causing the default context @code{Voice} to be used. Adding
1790 @code{\once} applies the change during one timestep only.
1792 @lilypond[quote,verbatim,relative=2]
1794 \once \override Stem.thickness = #4.0
1799 The @code{\override} must be done before the object is
1800 started. Therefore, when altering @emph{Spanner} objects such as slurs
1801 or beams, the @code{\override} command must be executed at the moment
1802 when the object is created. In this example,
1804 @lilypond[quote,verbatim,relative=2]
1805 \override Slur.thickness = #3.0
1807 \override Beam.beam-thickness = #0.6
1812 the slur is fatter but the beam is not. This is because the command for
1813 @code{Beam} comes after the Beam is started, so it has no effect.
1815 Analogous to @code{\unset}, the @code{\revert} command for a context
1816 undoes an @code{\override} command; like with @code{\unset}, it only
1817 affects settings that were made in the same context. In other words, the
1818 @code{\revert} in the next example does not do anything.
1821 \override Voice.Stem.thickness = #4.0
1822 \revert Staff.Stem.thickness
1825 Some tweakable options are called @q{subproperties} and reside inside
1826 properties. To tweak those, use commands of the form
1828 @c leave this as a long long
1830 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1837 \override Stem.details.beamed-lengths = #'(4 4 3)
1843 Internals Reference:
1844 @rinternals{Backend},
1845 @rinternals{All layout objects},
1846 @rinternals{OverrideProperty},
1847 @rinternals{RevertProperty},
1848 @rinternals{PropertySet}.
1851 The back-end is not very strict in type-checking object properties.
1852 Cyclic references in Scheme values for properties can cause hangs
1853 or crashes, or both.
1856 @node The set command
1857 @subsection The @code{@bs{}set} command
1861 @cindex changing properties
1863 Each context has a set of @emph{properties}, variables contained
1864 in that context. Context properties are changed with the @code{\set}
1865 command, which has the following syntax:
1868 \set @var{context}.@var{property} = #@var{value}
1871 @var{value} is a Scheme object, which is why it must be preceded by
1872 the @code{#}@tie{}character.
1874 Contexts properties are usually named in
1875 @code{studlyCaps}. They mostly control the translation from
1876 music to notation, e.g. @code{localKeySignature} (for determining
1877 whether to print accidentals), or @code{measurePosition} (for
1878 determining when to print a bar line). Context properties can
1879 change value over time while interpreting a piece of music;
1880 @code{measurePosition} is an obvious example of
1881 this. Context properties are modified with @code{\set}.
1883 For example, multimeasure rests will be combined into a single bar
1884 if the context property @code{skipBars} is set to @code{#t}:
1886 @lilypond[quote,verbatim,relative=2]
1888 \set Score.skipBars = ##t
1892 If the @var{context} argument is left out, then the property will be
1893 set in the current bottom context (typically @code{ChordNames},
1894 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1896 @lilypond[quote,verbatim,relative=2]
1897 \set Score.autoBeaming = ##f
1901 \set autoBeaming = ##t
1909 The change is applied @q{on-the-fly}, during the music, so that the
1910 setting only affects the second group of eighth notes.
1912 Note that the bottom-most context does not always contain the property
1913 that you wish to change -- for example, attempting to set the
1914 @code{skipBars} property of the default bottom context, in this case
1915 @code{Voice}, will have no effect, because skipBars is a property of
1916 the @code{Score} context.
1918 @lilypond[quote,verbatim,relative=2]
1924 Contexts are hierarchical, so if an enclosing context was specified, for
1925 example @code{Staff}, then the change would also apply to all
1926 @code{Voice}s in the current staff.
1930 The @code{\unset} command:
1933 \unset @var{context}.@var{property}
1937 is used to remove the definition of @var{property} from
1938 @var{context}. This command removes
1939 the definition only if it is set in @var{context}.
1940 Properties that have been set in enclosing contexts will
1941 not be altered by an unset in an enclosed context:
1943 @lilypond[quote,verbatim,relative=2]
1944 \set Score.autoBeaming = ##t
1949 \unset Score.autoBeaming
1957 Like @code{\set}, the @var{context} argument does not have to be
1958 specified for a bottom context, so the two statements
1961 \set Voice.autoBeaming = ##t
1962 \set autoBeaming = ##t
1966 are equivalent if the current bottom context is @code{Voice}.
1970 Preceding a @code{\set} command by @code{\once} makes the
1971 setting apply to only a single time-step:
1973 @lilypond[quote,verbatim,relative=2]
1975 \once \set fontSize = #4.7
1980 A full description of all available context properties is in the
1981 internals reference, see
1983 @rinternals{Tunable context properties}.
1986 Translation @expansion{} Tunable context properties.
1990 Internals Reference:
1991 @rinternals{Tunable context properties}.
1994 @node The override command
1995 @subsection The @code{\override} command
1997 @cindex grob properties
1998 @cindex properties, grob
2001 There is a special type of context property: the grob
2002 description. Grob descriptions are named in @code{StudlyCaps}
2003 (starting with capital letters). They contain the
2004 @q{default settings} for a particular kind of grob as an
2005 association list. See @file{scm/define-grobs.scm}
2006 to see the settings for each grob description. Grob descriptions
2007 are modified with @code{\override}.
2009 The syntax for the @code{\override} command is
2012 \override [@var{context}.]@var{GrobName}.@var{property} = #@var{value}
2015 For example, we can increase the thickness of a note stem by
2016 overriding the @code{thickness} property of the @code{Stem}
2019 @lilypond[quote,verbatim,relative=2]
2021 \override Voice.Stem.thickness = #3.0
2025 If no context is specified in an @code{\override}, the bottom
2028 @lilypond[quote,verbatim,relative=2]
2029 { \override Staff.Stem.thickness = #3.0
2033 \override Stem.thickness = #0.5
2042 Some tweakable options are called @q{subproperties} and reside inside
2043 properties. To tweak those, use commands in the form
2046 \override Stem.details.beamed-lengths = #'(4 4 3)
2049 or to modify the ends of spanners, use a form like these
2052 \override TextSpanner.bound-details.left.text = #"left text"
2053 \override TextSpanner.bound-details.right.text = #"right text"
2057 @cindex reverting overrides
2058 @cindex overrides, reverting
2060 The effects of @code{\override} can be undone by @code{\revert}.
2062 The syntax for the @code{\revert} command is
2065 \revert [@var{context}.]@var{GrobName}.@var{property}
2070 @lilypond[quote,verbatim,relative=2]
2072 \override Voice.Stem.thickness = #3.0
2074 \revert Voice.Stem.thickness
2078 The effects of @code{\override} and @code{\revert} apply to all
2079 grobs in the affected context from the current time forward:
2081 @lilypond[quote,verbatim,relative=2]
2086 \override Staff.Stem.thickness = #3.0
2090 \revert Staff.Stem.thickness
2098 @cindex overriding for only one moment
2100 @code{\once} can be used with @code{\override}
2101 to affect only the current time step:
2103 @lilypond[quote,verbatim,relative=2]
2107 \override Stem.thickness = #3.0
2111 \once \override Stem.thickness = #3.0
2120 Commands which change output generally look like
2123 \override Voice.Stem.thickness = #3.0
2127 To construct this tweak we must determine these bits of information:
2130 @item the context: here @code{Voice}.
2131 @item the layout object: here @code{Stem}.
2132 @item the layout property: here @code{thickness}.
2133 @item a sensible value: here @code{3.0}.
2136 @cindex internal documentation
2137 @cindex finding graphical objects
2138 @cindex graphical object descriptions
2141 @cindex internal documentation
2143 For many properties, regardless of the data type of the property, setting the
2144 property to false (@code{#f}) will result in turning it off, causing
2145 LilyPond to ignore that property entirely. This is particularly useful for
2146 turning off grob properties which may otherwise be causing problems.
2148 We demonstrate how to glean this information from the notation manual
2149 and the program reference.
2153 Internals Reference:
2154 @rinternals{Backend}
2157 @node The tweak command
2158 @subsection The @code{\tweak} command
2163 Changing grob properties
2164 with @code{\override} causes the changes to apply to all of the
2165 given grobs in the context at the moment the change applies.
2166 Sometimes, however, it is desirable to have changes apply to just
2167 one grob, rather than to all grobs in the affected context. This is
2168 accomplished with the @code{\tweak} command, which has the following
2172 \tweak [@var{layout-object}.]@var{grob-property} @var{value}
2175 Specifying @var{layout-object} is optional.
2176 The @code{\tweak} command applies to the music object that immediately
2177 follows @var{value} in the music stream.
2180 In some cases, it is possible to take a short-cut for tuning
2181 graphical objects. For objects that are created directly from
2182 an item in the input file, you can use the @code{\tweak} command.
2185 @lilypond[relative=2,verbatim,quote]
2190 \tweak duration-log #1
2199 The main use of the @code{\tweak} command is to modify just
2200 one of a number of notation elements which start at the same musical
2201 moment, like the notes of a chord, or tuplet brackets which start
2204 The @code{\tweak} command sets a property in the following object
2205 directly, without requiring the grob name or context to be
2206 specified. For this to work, it is necessary for the @code{\tweak}
2207 command to remain immediately adjacent to the object to which it is
2208 to apply after the input file has been converted to a music stream.
2209 This is often not the case, as many additional elements are inserted
2210 into the music stream implicitly. For example, when a note which is
2211 not part of a chord is processed, LilyPond implicitly inserts a
2212 @code{ChordEvent} event before the note, so separating the tweak
2213 from the note. However, if chord symbols are placed round the
2214 tweak and the note, the @code{\tweak} command comes after the
2215 @code{ChordEvent} in the music stream, so remaining adjacent to the
2216 note, and able to modify it.
2220 @lilypond[relative=2,verbatim,quote]
2221 <\tweak color #red c>4
2227 @lilypond[relative=2,verbatim,quote]
2228 \tweak color #red c4
2233 For an introduction to the syntax and uses of the tweak command
2234 see @rlearning{Tweaking methods}.
2236 When several similar items are placed at the same musical moment,
2237 the @code{\override} command cannot be used to modify just one of
2238 them -- this is where the @code{\tweak} command must be used.
2239 Items which may appear more than once at the same musical moment
2240 include the following:
2242 @c TODO expand to include any further uses of \tweak
2244 @item note heads of notes inside a chord
2245 @item articulation signs on a single note
2246 @item ties between notes in a chord
2247 @item tuplet brackets starting at the same time
2250 @c TODO add examples of these
2252 @cindex chord, modifying one note in
2254 In this example, the color of one note head and the type of another
2255 note head are modified within a single chord:
2257 @lilypond[relative=2,verbatim,quote]
2262 \tweak duration-log #1
2267 @code{\tweak} can be used to modify slurs:
2269 @lilypond[verbatim,quote,relative=1]
2270 c-\tweak thickness #5 ( d e f)
2274 For the @code{\tweak} command to work, it must
2275 remain immediately adjacent to the object to which it is
2276 to apply after the input file has been converted to a music stream.
2277 Tweaking a whole chord does not do anything since its music event
2278 only acts as a container, and all layout objects are created from events
2279 inside of the @code{EventChord}:
2281 @lilypond[relative=2,verbatim,quote]
2282 \tweak color #red c4
2283 \tweak color #red <c e>4
2284 <\tweak color #red c e>4
2287 The simple @code{\tweak} command cannot be used to modify any object
2288 that is not directly created from the input. In particular
2289 it will not affect stems, automatic
2290 beams or accidentals, since these are generated later by
2291 @code{NoteHead} layout objects rather than by music elements in the
2294 Such indirectly created layout objects can be tweaked using the form
2295 of the @code{\tweak} command in which the grob name is specified
2298 @lilypond[relative=2,verbatim,quote]
2299 \tweak Stem.color #red
2300 \tweak Beam.color #green c8 e
2301 <c e \tweak Accidental.font-size #-3 ges>4
2304 @code{\tweak} cannot be used to modify clefs or time
2305 signatures, since these become separated from any preceding
2306 @code{\tweak} command in the input stream by the automatic
2307 insertion of extra elements required to specify the context.
2309 Several @code{\tweak} commands may be placed before a
2310 notational element -- all affect it:
2312 @lilypond[verbatim,quote,relative=1]
2314 -\tweak style #'dashed-line
2315 -\tweak dash-fraction #0.2
2316 -\tweak thickness #3
2322 The music stream which is generated from a section of an input file,
2323 including any automatically inserted elements, may be examined,
2324 see @rextend{Displaying music expressions}. This may be helpful in
2325 determining what may be modified by a @code{\tweak} command, or
2326 in determining how to adjust the input to make a @code{\tweak}
2331 @rlearning{Tweaking methods}.
2334 @rextend{Displaying music expressions}.
2338 @cindex tweaking control points
2339 @cindex control points, tweaking
2341 The @code{\tweak} command cannot be used to modify the control
2342 points of just one of several ties in a chord, other than the first
2343 one encountered in the input file.
2345 @node set versus override
2346 @subsection @code{\set} vs. @code{\override}
2348 @c TODO -- This section is probably unnecessary now.
2351 We have seen two methods of changing properties: @code{\set} and
2352 @code{\override}. There are actually two different kinds of
2355 @code{fontSize} is a special property: it is equivalent to
2356 entering @code{\override @dots{} #'font-size} for all pertinent
2357 objects. Since this is a common change, the special
2358 property (modified with @code{\set}) was created.
2363 @node Modifying alists
2364 @subsection Modifying alists
2366 Some user-configurable properties are internally represented as
2367 @emph{alists} (association lists), which store pairs of
2368 @emph{keys} and @emph{values}. The structure of an alist is:
2371 '((@var{key1} . @var{value1})
2372 (@var{key2} . @var{value2})
2373 (@var{key3} . @var{value3})
2377 If an alist is a grob property or @code{\paper} variable, its keys
2378 can be modified individually without affecting other keys.
2380 For example, to reduce the space between adjacent staves in a
2381 staff-group, use the @code{staff-staff-spacing} property of the
2382 @code{StaffGrouper} grob. The property is an alist with four
2383 keys: @code{basic-distance}, @code{minimum-distance},
2384 @code{padding}, and @code{stretchability}. The standard settings
2385 for this property are listed in the @qq{Backend} section of the
2386 Internals Reference (see @rinternals{StaffGrouper}):
2389 '((basic-distance . 9)
2390 (minimum-distance . 7)
2392 (stretchability . 5))
2395 One way to bring the staves closer together is by reducing the
2396 value of the @code{basic-distance} key (@code{9}) to match the
2397 value of @code{minimum-distance} (@code{7}). To modify a single
2398 key individually, use a @emph{nested declaration}:
2400 @lilypond[quote,verbatim]
2401 % default space between staves
2403 \new Staff { \clef treble c''1 }
2404 \new Staff { \clef bass c1 }
2407 % reduced space between staves
2408 \new PianoStaff \with {
2409 % this is the nested declaration
2410 \override StaffGrouper.staff-staff-spacing.basic-distance = #7
2412 \new Staff { \clef treble c''1 }
2413 \new Staff { \clef bass c1 }
2417 Using a nested declaration will update the specified key (such as
2418 @code{basic-distance} in the above example) without altering any
2419 other keys already set for the same property.
2421 Now suppose we want the staves to be as close as possible without
2422 overlapping. The simplest way to do this is to set all four alist
2423 keys to zero. However, it is not necessary to enter four nested
2424 declarations, one for each key. Instead, the property can be
2425 completely re-defined with one declaration, as an alist:
2427 @lilypond[quote,verbatim]
2428 \new PianoStaff \with {
2429 \override StaffGrouper.staff-staff-spacing =
2430 #'((basic-distance . 0)
2431 (minimum-distance . 0)
2433 (stretchability . 0))
2435 \new Staff { \clef treble c''1 }
2436 \new Staff { \clef bass c1 }
2440 Note that any keys not explicitly listed in the alist definition
2441 will be reset to their @emph{default-when-unset} values. In the
2442 case of @code{staff-staff-spacing}, any unset key-values would be
2443 reset to zero (except @code{stretchability}, which takes the value
2444 of @code{basic-distance} when unset). Thus the following two
2445 declarations are equivalent:
2448 \override StaffGrouper.staff-staff-spacing =
2449 #'((basic-distance . 7))
2451 \override StaffGrouper.staff-staff-spacing =
2452 #'((basic-distance . 7)
2453 (minimum-distance . 0)
2455 (stretchability . 7))
2458 One (possibly unintended) consequence of this is the removal of
2459 any standard settings that are set in an initialization file and
2460 loaded each time an input file is compiled. In the above example,
2461 the standard settings for @code{padding} and
2462 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2463 are reset to their default-when-unset values (zero for both keys).
2464 Defining a property or variable as an alist (of any size) will
2465 always reset all unset key-values to their default-when-unset
2466 values. Unless this is the intended result, it is safer to update
2467 key-values individually with a nested declaration.
2469 @warning{Nested declarations will not work for context property
2470 alists (such as @code{beamExceptions}, @code{keySignature},
2471 @code{timeSignatureSettings}, etc.). These properties can only be
2472 modified by completely re-defining them as alists.}
2475 @node Useful concepts and properties
2476 @section Useful concepts and properties
2481 * Direction and placement::
2482 * Distances and measurements::
2483 * Staff symbol properties::
2485 * Visibility of objects::
2487 * Rotating objects::
2491 @subsection Input modes
2493 The way in which the notation contained within an input file is
2494 interpreted is determined by the current input mode.
2498 This is activated with the @code{\chordmode} command, and causes
2499 input to be interpreted with the syntax of chord notation, see
2500 @ref{Chord notation}. Chords are rendered as notes on a staff.
2502 Chord mode is also activated with the @code{\chords} command.
2503 This also creates a new @code{ChordNames} context and
2504 causes the following input to be interpreted with the syntax of
2505 chord notation and rendered as chord names in the @code{ChordNames}
2506 context, see @ref{Printing chord names}.
2510 This is activated with the @code{\drummode} command, and causes
2511 input to be interpreted with the syntax of drum notation, see
2512 @ref{Basic percussion notation}.
2514 Drum mode is also activated with the @code{\drums} command.
2515 This also creates a new @code{DrumStaff} context and causes the
2516 following input to be interpreted with the syntax of drum notation
2517 and rendered as drum symbols on a drum staff, see @ref{Basic
2518 percussion notation}.
2520 @strong{Figure mode}
2522 This is activated with the @code{\figuremode} command, and causes
2523 input to be interpreted with the syntax of figured bass, see
2524 @ref{Entering figured bass}.
2526 Figure mode is also activated with the @code{\figures} command.
2527 This also creates a new @code{FiguredBass} context and causes the
2528 following input to be interpreted with the figured bass syntax
2529 and rendered as figured bass symbols in the @code{FiguredBass}
2530 context, see @ref{Introduction to figured bass}.
2532 @strong{Fret and tab modes}
2534 There are no special input modes for entering fret and tab symbols.
2536 To create tab diagrams, enter notes or chords in note mode and
2537 render them in a @code{TabStaff} context, see
2538 @ref{Default tablatures}.
2540 To create fret diagrams above a staff, you have two choices.
2541 You can either use the @code{FretBoards} context (see
2542 @ref{Automatic fret diagrams} or you can enter them as a markup
2543 above the notes using the @code{\fret-diagram} command (see
2544 @ref{Fret diagram markups}).
2546 @strong{Lyrics mode}
2548 This is activated with the @code{\lyricmode} command, and causes
2549 input to be interpreted as lyric syllables with optional durations
2550 and associated lyric modifiers, see @ref{Vocal music}.
2552 Lyric mode is also activated with the @code{\addlyrics} command.
2553 This also creates a new @code{Lyrics} context and an implicit
2554 @code{\lyricsto} command which associates the following lyrics
2555 with the preceding music.
2557 @strong{Markup mode}
2559 This is activated with the @code{\markup} command, and causes
2560 input to be interpreted with the syntax of markup, see
2561 @ref{Text markup commands}.
2563 @c silly work-around for texinfo broken-ness
2564 @c (@strong{Note...} causes a spurious cross-reference in Info)
2567 This is the default mode or it may be activated with the
2568 @code{\notemode} command. Input is interpreted as pitches,
2569 durations, markup, etc and typeset as musical notation on a staff.
2571 It is not normally necessary to specify note mode explicitly, but
2572 it may be useful to do so in certain situations, for example if you
2573 are in lyric mode, chord mode or any other mode and want to insert
2574 something that only can be done with note mode syntax.
2576 For example, to indicate dynamic markings for the verses of a
2577 choral pieces it is necessary to enter note mode to interpret
2580 @lilypond[verbatim,relative=2,quote]
2583 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2587 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2594 @node Direction and placement
2595 @subsection Direction and placement
2597 In typesetting music the direction and placement of many items is
2598 a matter of choice. For example, the stems of notes can
2599 be directed up or down; lyrics, dynamics, and other expressive
2600 marks may be placed above or below the staff; text may be aligned
2601 left, right or center; etc. Most of these choices may be left to
2602 be determined automatically by LilyPond, but in some cases it may
2603 be desirable to force a particular direction or placement.
2606 * Articulation direction indicators::
2607 * The direction property::
2610 @node Articulation direction indicators
2611 @unnumberedsubsubsec Articulation direction indicators
2613 By default some directions are always up or always down (e.g.
2614 dynamics or fermata), while other things can alternate between
2615 up or down based on the stem direction (like slurs or accents).
2617 @c TODO Add table showing these
2619 The default action may be overridden by prefixing the articulation
2620 by a @emph{direction indicator}. Three direction indicators are
2621 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2622 and @code{-} (meaning @qq{use default direction}). The direction
2623 indicator can usually be omitted, in which case @code{-} is assumed,
2624 but a direction indicator is @strong{always} required before
2627 @item @code{\tweak} commands
2628 @item @code{\markup} commands
2629 @item @code{\tag} commands
2630 @item string markups, e.g. -"string"
2631 @item fingering instructions, e.g. @w{@code{-1}}
2632 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2635 Direction indicators affect only the next note:
2637 @lilypond[verbatim,quote,relative=2]
2644 @node The direction property
2645 @unnumberedsubsubsec The direction property
2647 The position or direction of many layout objects is controlled by the
2648 @code{direction} property.
2650 The value of the @code{direction} property may be set to @code{1},
2651 meaning @qq{up} or @qq{above}, or to @w{@code{-1}}, meaning @qq{down} or
2652 @qq{below}. The symbols @code{UP} and @code{DOWN} may be used instead
2653 of @code{1} and @w{@code{-1}} respectively. The default direction may
2654 be specified by setting @code{direction} to @code{0} or @code{CENTER}.
2655 Alternatively, in many cases predefined commands exist to specify the
2656 direction. These are of the form
2659 @code{\xxxUp}, @code{\xxxDown} or @code{\xxxNeutral}
2663 where @code{\xxxNeutral} means @qq{use the default} direction.
2664 See @rlearning{Within-staff objects}.
2666 In a few cases, arpeggio for example, the value of the @code{direction}
2667 property can specify whether the object is to be placed to the right or
2668 left of the parent. In this case @w{@code{-1}} or @code{LEFT} means
2669 @qq{to the left} and @code{1} or @code{RIGHT} means @qq{to the right}.
2670 @code{0} or @code{CENTER} means @qq{use the default} direction.
2673 These all have side-axis set to #X
2674 AmbitusAccidental - direction has no effect
2676 StanzaNumber - not tried
2677 TrillPitchAccidental - not tried
2678 TrillPitchGroup - not tried
2681 These indications affect all notes until they are canceled.
2683 @lilypond[verbatim,quote,relative=2]
2692 In polyphonic music, it is generally better to specify an explicit
2693 @code{voice} than change an object's direction. For more information.
2694 See @ref{Multiple voices}.
2698 @rlearning{Within-staff objects}.
2701 @ref{Multiple voices}.
2704 @node Distances and measurements
2705 @subsection Distances and measurements
2707 @cindex distances, absolute
2708 @cindex distances, scaled
2715 Distances in LilyPond are of two types: absolute and scaled.
2717 Absolute distances are used for specifying margins, indents, and
2718 other page layout details, and are by default specified in
2719 millimeters. Distances may be specified in other units by
2720 following the quantity by @code{\mm}, @code{\cm},
2721 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2722 an inch). Page layout distances can also be specified in scalable
2723 units (see the following paragraph) by appending
2724 @code{\staff-space} to the quantity. Page layout is described in
2725 detail in @ref{Page layout}.
2727 Scaled distances are always specified in units of the staff-space
2728 or, rarely, the half staff-space. The staff-space is the distance
2729 between two adjacent staff lines. The default value can be changed
2730 globally by setting the global staff size, or it can be overridden
2731 locally by changing the @code{staff-space} property of
2732 @code{StaffSymbol}. Scaled distances automatically scale with any
2733 change to the either the global staff size or the
2734 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2735 automatically only with changes to the global staff size.
2736 The global staff size thus enables the overall size of a rendered
2737 score to be easily varied. For the methods of setting the global
2738 staff size see @ref{Setting the staff size}.
2742 If just a section of a score needs to be rendered to a different
2743 scale, for example an ossia section or a footnote, the global staff
2744 size cannot simply be changed as this would affect the entire score.
2745 In such cases the change in size is made by overriding both the
2746 @code{staff-space} property of @code{StaffSymbol} and the size of
2747 the fonts. A Scheme function, @code{magstep}, is available to
2748 convert from a font size change to the equivalent change in
2749 @code{staff-space}. For an explanation and an example of its use,
2750 see @rlearning{Length and thickness of objects}.
2754 @rlearning{Length and thickness of objects}.
2758 @ref{Setting the staff size}.
2761 @node Staff symbol properties
2762 @subsection Staff symbol properties
2764 @cindex adjusting staff symbol
2765 @cindex drawing staff symbol
2766 @cindex staff symbol, setting of
2768 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2769 @c Need to think of uses for these properties. Eg 'line-positions
2770 @c is used in a snippet to thicken centre line.
2771 @c If retained, add @ref to here in 1.6.2 -td
2773 The vertical position of staff lines and the number of staff lines
2774 can be defined at the same time. As the following example shows,
2775 note positions are not influenced by the staff line positions.
2777 @warning{The @code{'line-positions} property overrides the
2778 @code{'line-count} property. The number of staff lines is
2779 implicitly defined by the number of elements in the list of values
2780 for @code{'line-positions}.}
2782 @lilypond[verbatim,quote,relative=1]
2784 \override StaffSymbol.line-positions = #'(7 3 0 -4 -6 -7)
2789 The width of a staff can be modified. The units are staff
2790 spaces. The spacing of objects inside the staff is not affected by
2793 @lilypond[verbatim,quote,relative=1]
2795 \override StaffSymbol.width = #23
2802 @subsection Spanners
2804 Many objects of musical notation extend over several notes or even
2805 several bars. Examples are slurs, beams, tuplet brackets, volta
2806 repeat brackets, crescendi, trills, and glissandi. Such objects
2807 are collectively called @qq{spanners}, and have special properties to control
2808 their appearance and behaviour. Some of these properties are common
2809 to all spanners; others are restricted to a sub-set of the spanners.
2811 All spanners support the @code{spanner-interface}. A few, essentially
2812 those that draw a straight line between the two objects, support in
2813 addition the @code{line-spanner-interface}.
2816 * Using the spanner-interface::
2817 * Using the line-spanner-interface::
2820 @node Using the spanner-interface
2821 @unnumberedsubsubsec Using the @code{spanner-interface}
2823 This interface provides two properties that apply to several spanners.
2825 @subsubsubheading The @code{minimum-length} property
2827 The minimum length of the spanner is specified by the
2828 @code{minimum-length} property. Increasing this usually has the
2829 necessary effect of increasing the spacing of the notes between the
2830 two end points. However, this override has no effect on
2831 many spanners, as their length is determined by other considerations.
2832 A few examples where it is effective are shown below.
2842 Works as long as callback is made:
2846 Works not at all for:
2855 @lilypond[verbatim,quote,relative=2]
2858 % increase the length of the tie
2859 -\tweak minimum-length #5
2863 @lilypond[verbatim,quote,relative=2]
2865 \compressFullBarRests
2867 % increase the length of the rest bar
2868 \once \override MultiMeasureRest.minimum-length = #20
2873 @lilypond[verbatim,quote,relative=2]
2875 % increase the length of the hairpin
2876 \override Hairpin.minimum-length = #20
2880 This override can also be used to increase the length of slurs and
2883 @lilypond[verbatim,quote,relative=2]
2886 -\tweak minimum-length #5
2891 -\tweak minimum-length #5
2895 For some layout objects, the @code{minimum-length} property becomes
2896 effective only if the @code{set-spacing-rods} procedure is called
2897 explicitly. To do this, the @code{springs-and-rods} property should
2898 be set to @code{ly:spanner::set-spacing-rods}. For example,
2899 the minimum length of a glissando has no effect unless the
2900 @code{springs-and-rods} property is set:
2902 @lilypond[verbatim,quote,relative=1]
2906 % not effective alone
2907 \once \override Glissando.minimum-length = #20
2910 % effective only when both overrides are present
2911 \once \override Glissando.minimum-length = #20
2912 \once \override Glissando.springs-and-rods = #ly:spanner::set-spacing-rods
2916 The same is true of the @code{Beam} object:
2918 @lilypond[verbatim,quote,relative=1]
2919 % not effective alone
2920 \once \override Beam.minimum-length = #20
2923 % effective only when both overrides are present
2924 \once \override Beam.minimum-length = #20
2925 \once \override Beam.springs-and-rods = #ly:spanner::set-spacing-rods
2929 @subsubsubheading The @code{to-barline} property
2931 The second useful property of the @code{spanner-interface} is
2932 @code{to-barline}. By default this is true, causing hairpins and
2933 other spanners which are terminated on the first note of a measure to
2934 end instead on the immediately preceding bar line. If set to false,
2935 the spanner will extend beyond the bar line and end on the note
2938 @lilypond[verbatim,quote,relative=2]
2939 a \< a a a a \! a a a \break
2940 \override Hairpin.to-barline = ##f
2941 a \< a a a a \! a a a
2944 This property is not effective for all spanners. For example,
2945 setting it to @code{#t} has no effect on slurs or phrasing slurs
2946 or on other spanners for which terminating on the bar line would
2949 @node Using the line-spanner-interface
2950 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2952 Objects which support the @code{line-spanner-interface} include
2955 @item @code{DynamicTextSpanner}
2956 @item @code{Glissando}
2957 @item @code{TextSpanner}
2958 @item @code{TrillSpanner}
2959 @item @code{VoiceFollower}
2962 The routine responsible for drawing the stencils for these spanners is
2963 @code{ly:line-interface::print}. This routine determines the
2964 exact location of the two end points and draws a line
2965 between them, in the style requested. The locations of the two
2966 end points of the spanner are computed on-the-fly, but it is
2967 possible to override their Y-coordinates. The
2968 properties which need to be specified are nested
2969 two levels down within the property hierarchy, but the syntax of
2970 the @code{\override} command is quite simple:
2972 @lilypond[relative=2,quote,verbatim]
2974 \once \override Glissando.bound-details.left.Y = #3
2975 \once \override Glissando.bound-details.right.Y = #-2
2979 The units for the @code{Y} property are @code{staff-space}s,
2980 with the center line of the staff being the zero point.
2981 For the glissando, this is the value for @code{Y} at the
2982 X-coordinate corresponding to the center point of each note head,
2983 if the line is imagined to be extended to there.
2985 If @code{Y} is not set, the value is computed from the vertical
2986 position of the corresponding attachment point of the spanner.
2988 In case of a line break, the values for the end points are
2989 specified by the @code{left-broken} and @code{right-broken}
2990 sub-lists of @code{bound-details}. For example:
2992 @lilypond[relative=2,ragged-right,verbatim,quote]
2993 \override Glissando.breakable = ##t
2994 \override Glissando.bound-details.right-broken.Y = #-3
2995 c1 \glissando \break
3000 A number of further properties of the @code{left} and
3001 @code{right} sub-lists of the @code{bound-details} property
3002 may be modified in the same way as @code{Y}:
3006 This sets the Y-coordinate of the end point, in @code{staff-space}s
3007 offset from the staff center line. By default, it is the center of
3008 the bound object, so a glissando points to the vertical center of
3011 For horizontal spanners, such as text spanners and trill spanners,
3012 it is hardcoded to 0.
3015 This determines where the line starts and ends in the X-direction,
3016 relative to the bound object. So, a value of @w{@code{-1}} (or
3017 @code{LEFT}) makes the line start/end at the left side of the note
3018 head it is attached to.
3021 This is the absolute X-coordinate of the end point. It is usually
3022 computed on the fly, and overriding it has little useful effect.
3025 Line spanners may have symbols at the beginning or end, which is
3026 contained in this sub-property. This is for internal use; it is
3027 recommended that @code{text} be used instead.
3030 This is a markup that is evaluated to yield the stencil. It is used
3031 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
3033 @lilypond[quote,ragged-right,relative=2,verbatim]
3034 \override TextSpanner.bound-details.left.text
3035 = \markup { \small \bold Slower }
3036 c2\startTextSpan b c a\stopTextSpan
3039 @item stencil-align-dir-y
3040 @item stencil-offset
3041 Without setting one of these, the stencil is simply put at the
3042 end-point, centered on the line, as defined by the @code{X} and
3043 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
3044 or @code{stencil-offset} will move the symbol at the edge vertically
3045 relative to the end point of the line:
3047 @lilypond[relative=1,quote,verbatim]
3048 \override TextSpanner.bound-details.left.stencil-align-dir-y = #-2
3049 \override TextSpanner.bound-details.right.stencil-align-dir-y = #UP
3051 \override TextSpanner.bound-details.left.text = #"ggg"
3052 \override TextSpanner.bound-details.right.text = #"hhh"
3053 c4^\startTextSpan c c c \stopTextSpan
3056 Note that negative values move the text @emph{up}, contrary to the
3057 effect that might be expected, as a value of @w{@code{-1}} or
3058 @code{DOWN} means align the @emph{bottom} edge of the text with
3059 the spanner line. A value of @code{1} or @code{UP} aligns
3060 the top edge of the text with the spanner line.
3063 Setting this sub-property to @code{#t} produces an arrowhead at the
3067 This sub-property controls the space between the specified
3068 end point of the line and the actual end. Without padding, a
3069 glissando would start and end in the center of each note head.
3073 The music function @code{\endSpanners} terminates the spanner
3074 which starts on the immediately following note prematurely. It
3075 is terminated after exactly one note, or at the following bar line
3076 if @code{to-barline} is true and a bar line occurs before the next
3079 @lilypond[verbatim,quote,ragged-right,relative=2]
3081 c2 \startTextSpan c2 c2
3086 When using @code{\endSpanners} it is not necessary to close
3087 \startTextSpan with \stopTextSpan, nor is it necessary to close
3088 hairpins with @code{\!}.
3091 Internals Reference:
3092 @rinternals{TextSpanner},
3093 @rinternals{Glissando},
3094 @rinternals{VoiceFollower},
3095 @rinternals{TrillSpanner},
3096 @rinternals{line-spanner-interface}.
3099 @node Visibility of objects
3100 @subsection Visibility of objects
3102 @cindex objects, visibility of
3103 @cindex grobs, visibility of
3104 @cindex visibility of objects
3106 There are four main ways in which the visibility of layout objects
3107 can be controlled: their stencil can be removed, they can be made
3108 transparent, they can be colored white, or their
3109 @code{break-visibility} property can be overridden. The first
3110 three apply to all layout objects; the last to just a few -- the
3111 @emph{breakable} objects. The Learning Manual introduces these
3112 four techniques, see @rlearning{Visibility and color of objects}.
3114 There are also a few other techniques which are specific to
3115 certain layout objects. These are covered under Special
3119 * Removing the stencil::
3120 * Making objects transparent::
3121 * Painting objects white::
3122 * Using break-visibility::
3123 * Special considerations::
3127 @node Removing the stencil
3128 @unnumberedsubsubsec Removing the stencil
3130 @cindex stencil, removing
3132 Every layout object has a stencil property. By default this is set
3133 to the specific function which draws that object. If this property
3134 is overridden to @code{#f} no function will be called and the object
3135 will not be drawn. The default action can be recovered with
3138 @lilypond[quote,verbatim,relative=1]
3140 \override Score.BarLine.stencil = ##f
3142 \revert Score.BarLine.stencil
3146 @node Making objects transparent
3147 @unnumberedsubsubsec Making objects transparent
3149 @cindex transparent, making objects
3151 Every layout object has a transparent property which by default is
3152 set to @code{#f}. If set to @code{#t} the object still occupies
3153 space but is made invisible.
3155 @lilypond[quote,verbatim,relative=2]
3157 \once \override NoteHead.transparent = ##t
3161 @node Painting objects white
3162 @unnumberedsubsubsec Painting objects white
3164 @cindex objects, coloring
3165 @cindex coloring objects
3167 @cindex printing order
3168 @cindex overwriting objects
3169 @cindex objects, overwriting
3170 @cindex grobs, overwriting
3172 Every layout object has a color property which by default is set
3173 to @code{black}. If this is overridden to @code{white} the object
3174 will be indistinguishable from the white background. However,
3175 if the object crosses other objects the color of the crossing
3176 points will be determined by the order in which they are drawn,
3177 and this may leave a ghostly image of the white object, as shown
3180 @lilypond[quote,verbatim,relative=2]
3181 \override Staff.Clef.color = #white
3185 This may be avoided by changing the order of printing the objects.
3186 All layout objects have a @code{layer} property which should be set
3187 to an integer. Objects with the lowest value of @code{layer} are
3188 drawn first, then objects with progressively higher values are drawn,
3189 so objects with higher values overwrite objects with lower values.
3190 By default most objects are assigned a @code{layer} value of
3191 @code{1}, although a few objects, including @code{StaffSymbol} and
3192 @code{BarLine}, are assigned a value of @code{0}. The order of
3193 printing objects with the same value of @code{layer} is indeterminate.
3195 In the example above the white clef, with a default @code{layer}
3196 value of @code{1}, is drawn after the staff lines (default
3197 @code{layer} value @code{0}), so overwriting them. To change this,
3198 the @code{Clef} object must be given in a lower value of
3199 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
3201 @lilypond[quote,verbatim,relative=2]
3202 \override Staff.Clef.color = #white
3203 \override Staff.Clef.layer = #-1
3207 @node Using break-visibility
3208 @unnumberedsubsubsec Using break-visibility
3210 @c TODO Add making other objects breakable
3212 @cindex break-visibility
3214 Most layout objects are printed only once, but some like
3215 bar lines, clefs, time signatures and key signatures, may need
3216 to be printed twice when a line break occurs -- once at the end
3217 of the line and again at the start of the next line. Such
3218 objects are called @emph{breakable}, and have a property, the
3219 @code{break-visibility} property to control their visibility
3220 at the three positions in which they may appear -- at the
3221 start of a line, within a line if they are changed, and at the
3222 end of a line if a change takes place there.
3224 For example, the time signature
3225 by default will be printed at the start of the first line, but
3226 nowhere else unless it changes, when it will be printed at the
3227 point at which the change occurs. If this change occurs at the
3228 end of a line the new time signature will be printed at the start
3229 of the next line and a cautionary time signature will be printed
3230 at the end of the previous line as well.
3232 This behaviour is controlled by the @code{break-visibility}
3233 property, which is explained in
3234 @c Leave this ref on a newline - formats incorrectly otherwise -td
3235 @rlearning{Visibility and color of objects}. This property takes
3236 a vector of three booleans which, in order, determine whether the
3237 object is printed at the end of, within the body of, or at the
3238 beginning of a line. Or to be more precise, before a line break,
3239 where there is no line break, or after a line break.
3241 Alternatively, these eight combinations may be specified
3242 by pre-defined functions, defined in @file{scm/output-lib.scm},
3243 where the last three columns indicate whether the layout objects
3244 will be visible in the positions shown at the head of the columns:
3246 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {Before} {At no} {After}
3247 @headitem Function @tab Vector @tab Before @tab At no @tab After
3248 @headitem form @tab form @tab break @tab break @tab break
3250 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
3251 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
3252 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
3253 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
3254 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
3255 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
3256 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
3257 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
3260 The default settings of @code{break-visibility} depend on the
3261 layout object. The following table shows all the layout objects
3262 of interest which are affected by @code{break-visibility} and the
3263 default setting of this property:
3265 @multitable @columnfractions .3 .3 .4
3267 @headitem Layout object @tab Usual context @tab Default setting
3269 @c omit Ambitus as it appears not to be affected by break-visibility -td
3270 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
3271 @item @code{BarLine} @tab @code{Score} @tab calculated
3272 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
3273 @c omit the following item until it can be explained -td
3274 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
3275 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3276 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
3277 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
3278 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3279 @item @code{KeyCancellation} @tab @code{Staff} @tab @code{begin-of-line-invisible}
3280 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
3281 @c omit LeftEdge until it can be explained -td
3282 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
3283 @item @code{ClefModifier} @tab @code{Staff} @tab @code{begin-of-line-visible}
3284 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
3285 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
3289 The example below shows the use of the vector form to control the
3290 visibility of bar lines:
3292 @lilypond[quote,verbatim,relative=1,ragged-right]
3295 % Remove bar line at the end of the current line
3296 \once \override Score.BarLine.break-visibility = ##(#f #t #t)
3302 Although all three components of the vector used to override
3303 @code{break-visibility} must be present, not all of them are
3304 effective with every layout object, and some combinations may
3305 even give errors. The following limitations apply:
3308 @item Bar lines cannot be printed at start of line.
3309 @item A bar number cannot be printed at the start of the first
3310 line unless it is set to be different from 1.
3311 @item Clef -- see below
3312 @item Double percent repeats are either all printed or all
3313 suppressed. Use begin-of line-invisible to print and
3314 all-invisible to suppress.
3315 @item Key signature -- see below
3316 @item ClefModifier -- see below
3319 @node Special considerations
3320 @unnumberedsubsubsec Special considerations
3322 @subsubsubheading Visibility following explicit changes
3324 @cindex key signature, visibility following explicit change
3325 @cindex explicitKeySignatureVisibility
3326 @cindex clef, visibility following explicit change
3327 @cindex explicitClefVisibility
3329 The @code{break-visibility} property controls the visibility of
3330 key signatures and changes of clef only at the start of lines,
3331 i.e. after a break. It has no effect on the visibility of the
3332 key signature or clef following an explicit key change or an
3333 explicit clef change within or at the end of a line. In the
3334 following example the key signature following the explicit change
3335 to B-flat major is still visible, even though @code{all-invisible}
3338 @lilypond[quote,verbatim,relative=1,ragged-right]
3341 % Try to remove all key signatures
3342 \override Staff.KeySignature.break-visibility = #all-invisible
3350 The visibility of such explicit key signature and clef changes is
3351 controlled by the @code{explicitKeySignatureVisibility} and
3352 @code{explicitClefVisibility} properties. These are the equivalent
3353 of the @code{break-visibility} property and both take a vector of
3354 three booleans or the predefined functions listed above, exactly like
3355 @code{break-visibility}. Both are properties of the Staff context,
3356 not the layout objects themselves, and so they are set using the
3357 @code{\set} command. Both are set by default to @code{all-visible}.
3358 These properties control only the visibility of key signatures and
3359 clefs resulting from explicit changes and do not affect key
3360 signatures and clefs at the beginning of lines;
3361 @code{break-visibility} must still be overridden in the appropriate
3362 object to remove these.
3364 @lilypond[quote,verbatim,relative=1,ragged-right]
3367 \set Staff.explicitKeySignatureVisibility = #all-invisible
3368 \override Staff.KeySignature.break-visibility = #all-invisible
3375 @subsubsubheading Visibility of cancelling accidentals
3377 To remove the cancelling accidentals printed at an explicit key
3378 change, set the Staff context property @code{printKeyCancellation}
3381 @lilypond[quote,verbatim,relative=1,ragged-right]
3384 \set Staff.explicitKeySignatureVisibility = #all-invisible
3385 \set Staff.printKeyCancellation = ##f
3386 \override Staff.KeySignature.break-visibility = #all-invisible
3393 With these overrides only the accidentals before the notes remain
3394 to indicate the change of key.
3396 Note that when changing the key to C@tie{}major or A@tie{}minor
3397 the cancelling accidentals would be the @emph{only} indication of
3398 the key change. In this case setting @code{printKeyCancellation} to
3399 @code{#f} has no effect:
3401 @lilypond[quote,verbatim,relative=1,ragged-right]
3404 \set Staff.explicitKeySignatureVisibility = #all-invisible
3405 \set Staff.printKeyCancellation = ##f
3412 To suppress the cancelling accidentals even when the key is
3413 changed to C@tie{}major or A@tie{}minor, override
3414 the visibility of the @code{KeyCancellation} grob instead:
3416 @lilypond[quote,verbatim,relative=1,ragged-right]
3419 \set Staff.explicitKeySignatureVisibility = #all-invisible
3420 \override Staff.KeyCancellation.break-visibility = #all-invisible
3427 @c TODO Add visibility of cautionary accidentals before notes
3429 @subsubsubheading Automatic bars
3431 @cindex automaticBars
3432 @cindex bar lines, suppressing
3434 As a special case, the printing of bar lines can also be turned off
3435 by setting the @code{automaticBars} property in the Score context.
3436 If set to @code{#f}, bar lines will not be printed automatically;
3437 they must be explicitly created with a @code{\bar} command. Unlike
3438 the @code{\cadenzaOn} predefined command, measures are still counted.
3439 Bar generation will resume according to that count if this property
3440 is later set to @code{#t}. When set to @code{#f}, line breaks can
3441 occur only at explicit @code{\bar} commands.
3445 @subsubsubheading Transposed clefs
3447 @cindex transposed clefs, visibility of
3448 @cindex visibility of transposed clefs
3449 @cindex clefs, visibility of transposition
3451 The small transposition symbol on transposed clefs is produced by the
3452 @code{ClefModifier} layout object. Its visibility is automatically
3453 inherited from the @code{Clef} object, so it is not necessary to apply
3454 any required @code{break-visibility} overrides to the @code{ClefModifier}
3455 layout objects to suppress transposition symbols for invisible clefs.
3457 For explicit clef changes, the @code{explicitClefVisibility}
3458 property controls both the clef symbol and any transposition symbol
3463 @rlearning{Visibility and color of objects}.
3467 @subsection Line styles
3469 Some performance indications, e.g., @i{rallentando} and
3470 @i{accelerando} and @i{trills} are written as text and are
3471 extended over many measures with lines, sometimes dotted or wavy.
3473 These all use the same routines as the glissando for drawing the
3474 texts and the lines, and tuning their behavior is therefore also
3475 done in the same way. It is done with a spanner, and the routine
3476 responsible for drawing the spanners is
3477 @code{ly:line-interface::print}. This routine determines the
3478 exact location of the two @i{span points} and draws a line
3479 between them, in the style requested.
3481 Here is an example showing the different line styles available,
3482 and how to tune them.
3484 @lilypond[relative=2,ragged-right,verbatim,quote]
3486 \once \override Glissando.style = #'dashed-line
3488 \override Glissando.style = #'dotted-line
3490 \override Glissando.style = #'zigzag
3492 \override Glissando.style = #'trill
3496 The locations of the end-points of the spanner are computed
3497 on-the-fly for every graphic object, but it is possible to
3501 @lilypond[relative=2,ragged-right,verbatim,quote]
3503 \once \override Glissando.bound-details.right.Y = #-2
3507 The value for @code{Y} is set to @w{@code{-2}} for the right end
3508 point. The left side may be similarly adjusted by specifying
3509 @code{left} instead of @code{right}.
3511 If @code{Y} is not set, the value is computed from the vertical
3512 position of the left and right attachment points of the spanner.
3514 Other adjustments of spanners are possible, for details, see
3517 @node Rotating objects
3518 @subsection Rotating objects
3520 Both layout objects and elements of markup text can be rotated by
3521 any angle about any point, but the method of doing so differs.
3524 * Rotating layout objects::
3528 @node Rotating layout objects
3529 @unnumberedsubsubsec Rotating layout objects
3531 @cindex rotating objects
3532 @cindex objects, rotating
3534 All layout objects which support the @code{grob-interface} can be
3535 rotated by setting their @code{rotation} property. This takes a
3536 list of three items: the angle of rotation counter-clockwise,
3537 and the x and y coordinates of the point relative to the object's
3538 reference point about which the rotation is to be performed. The
3539 angle of rotation is specified in degrees and the coordinates in
3542 The angle of rotation and the coordinates of the rotation point must
3543 be determined by trial and error.
3545 @cindex hairpins, angled
3546 @cindex angled hairpins
3548 There are only a few situations where the rotation of layout
3549 objects is useful; the following example shows one situation where
3552 @lilypond[quote,verbatim,relative=1]
3554 \override Hairpin.rotation = #'(20 -1 0)
3558 @node Rotating markup
3559 @unnumberedsubsubsec Rotating markup
3561 All markup text can be rotated to lie at any angle by prefixing it
3562 with the @code{\rotate} command. The command takes two arguments:
3563 the angle of rotation in degrees counter-clockwise and the text to
3564 be rotated. The extents of the text are not rotated: they take
3565 their values from the extremes of the x and y coordinates of the
3566 rotated text. In the following example the
3567 @code{outside-staff-priority} property for text is set to @code{#f}
3568 to disable the automatic collision avoidance, which would push some
3569 of the text too high.
3571 @lilypond[quote,verbatim,relative=1]
3572 \override TextScript.outside-staff-priority = ##f
3573 g4^\markup { \rotate #30 "a G" }
3574 b^\markup { \rotate #30 "a B" }
3575 des^\markup { \rotate #30 "a D-Flat" }
3576 fis^\markup { \rotate #30 "an F-Sharp" }
3579 @node Advanced tweaks
3580 @section Advanced tweaks
3582 This section discusses various approaches to fine tuning the
3583 appearance of the printed score.
3586 * Aligning objects::
3587 * Vertical grouping of grobs::
3588 * Modifying stencils::
3589 * Modifying shapes::
3590 * Unpure-pure containers::
3595 @rlearning{Tweaking output},
3596 @rlearning{Other sources of information}.
3599 @ref{Explaining the Internals Reference},
3600 @ref{Modifying properties}.
3603 @rextend{Interfaces for programmers}.
3606 @file{scm/define-grobs.scm}.
3609 @rlsr{Tweaks and overrides}.
3611 Internals Reference:
3612 @rinternals{All layout objects}.
3615 @node Aligning objects
3616 @subsection Aligning objects
3618 Graphical objects which support the @code{self-alignment-interface}
3619 and/or the @code{side-position-interface} can be aligned to a previously
3620 placed object in a variety of ways. For a list of these objects, see
3621 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3623 All graphical objects have a reference point, a horizontal extent and a
3624 vertical extent. The horizontal extent is a pair of numbers
3625 giving the displacements from the reference point of the left and
3626 right edges, displacements to the left being negative. The vertical
3627 extent is a pair of numbers giving the displacement from the reference
3628 point to the bottom and top edges, displacements down being negative.
3630 An object's position on a staff is given by the values of the
3631 @code{X-offset} and @code{Y-offset} properties. The value of
3632 @code{X-offset} gives the displacement from the X coordinate of
3633 the reference point of the parent object, and the value of
3634 @code{Y-offset} gives the displacement from the center line of the
3635 staff. The values of @code{X-offset} and @code{Y-offset} may
3636 be set directly or may be set to be calculated by procedures in order
3637 to achieve alignment with the parent object.
3639 @warning{Many objects have special positioning considerations which
3640 cause any setting of @code{X-offset} or @code{Y-offset} to be
3641 ignored or modified, even though the object supports the
3642 @code{self-alignment-interface}. Overriding the @code{X-offset}
3643 or @code{Y-offset} properties to a fixed value causes the respective
3644 @code{self-alignment} property to be disregarded.}
3646 For example, an accidental can be repositioned vertically by setting
3647 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3649 Rehearsal marks may be aligned with breakable objects such as bar
3650 lines, clef symbols, time signature symbols and key signatures. There
3651 are special properties to be found in the @code{break-aligned-interface}
3652 for positioning rehearsal marks on such objects.
3656 @ref{Using the break-alignable-interface}.
3659 @rextend{Callback functions}.
3662 * Setting X-offset and Y-offset directly::
3663 * Using the side-position-interface::
3664 * Using the self-alignment-interface::
3665 * Using the break-alignable-interface::
3668 @node Setting X-offset and Y-offset directly
3669 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3671 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3672 properties of many objects. The following example shows three
3673 notes with the default fingering position and the positions with @code{X-offset}
3674 and @code{Y-offset} modified.
3676 @lilypond[verbatim,quote,relative=2]
3683 -\tweak X-offset #-1
3690 @node Using the side-position-interface
3691 @unnumberedsubsubsec Using the @code{side-position-interface}
3693 An object which supports the @code{side-position-interface} can be
3694 placed next to its parent object so that
3695 the specified edges of the two objects touch. The object may be
3696 placed above, below, to the right or to the left of the parent.
3697 The parent cannot be specified; it is determined by the order of
3698 elements in the input stream. Most objects have the associated
3699 note head as their parent.
3701 The values of the @code{side-axis} and @code{direction} properties
3702 determine where the object is to be placed, as follows:
3704 @c TODO add an example of each to the table
3706 @multitable @columnfractions .3 .3 .3
3707 @headitem @code{side-axis} @tab @code{direction} @tab
3708 @headitem property @tab property @tab Placement
3710 @item @code{0} @tab @code{-1} @tab left
3711 @item @code{0} @tab @code{1} @tab right
3712 @item @code{1} @tab @code{-1} @tab below
3713 @item @code{1} @tab @code{1} @tab above
3717 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3718 the procedure @code{ly:side-position-interface::x-aligned-side}.
3719 This procedure will return the correct value of @code{X-offset} to
3720 place the object to the left or right side of the parent according
3721 to value of @code{direction}.
3723 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3724 the procedure @code{ly:side-position-interface::y-aligned-side}.
3725 This procedure will return the correct value of @code{Y-offset} to
3726 place the object to the top or bottom of the parent according
3727 to value of @code{direction}.
3729 @c TODO Add examples
3731 @node Using the self-alignment-interface
3732 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3734 @subsubsubheading Self-aligning objects horizontally
3736 The horizontal alignment of an object which supports the
3737 @code{self-alignment-interface} is controlled by the value of
3738 the @code{self-alignment-X} property, provided the object's
3739 @code{X-offset} property is set to
3740 @code{ly:self-alignment-interface::x-aligned-on-self}.
3741 @code{self-alignment-X} may be given any
3742 real value, in units of half the total X extent of the
3743 object. Negative values move the object to the right, positive
3744 to the left. A value of @code{0} centers the object on the
3745 reference point of its parent, a value of @w{@code{-1}} aligns the
3746 left edge of the object on the reference point of its parent,
3747 and a value of @code{1} aligns the right edge of the object on the
3748 reference point of its parent. The symbols @code{LEFT},
3749 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3750 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3752 Normally the @code{\override} command would be used to modify the
3753 value of @code{self-alignment-X}, but the @code{\tweak} command
3754 can be used to separately align several annotations on a single
3757 @lilypond[quote,verbatim,relative=1]
3759 -\tweak self-alignment-X #-1
3761 -\tweak self-alignment-X #0
3763 -\tweak self-alignment-X #RIGHT
3765 -\tweak self-alignment-X #-2.5
3766 ^"aligned further to the right"
3769 @subsubsubheading Self-aligning objects vertically
3771 Objects may be aligned vertically in an analogous way to aligning
3772 them horizontally if the @code{Y-offset} property is set to
3773 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3774 other mechanisms are often involved in vertical alignment: the
3775 value of @code{Y-offset} is just one variable taken into account.
3776 This may make adjusting the value of some objects tricky.
3777 The units are just half the vertical extent of the object, which
3778 is usually quite small, so quite large numbers may be required.
3779 A value of @w{@code{-1}} aligns the lower edge of the object with
3780 the reference point of the parent object, a value of @code{0}
3781 aligns the center of the object with the reference point of the
3782 parent, and a value of @code{1} aligns the top edge of the object
3783 with the reference point of the parent. The symbols @code{DOWN},
3784 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3785 @code{0}, and @code{1}, respectively.
3787 @subsubsubheading Self-aligning objects in both directions
3789 By setting both @code{X-offset} and @code{Y-offset}, an object may
3790 be aligned in both directions simultaneously.
3792 The following example shows how to adjust a fingering mark so
3793 that it nestles close to the note head.
3795 @lilypond[quote,verbatim,relative=2]
3797 -\tweak self-alignment-X #0.5 % move horizontally left
3798 -\tweak Y-offset #ly:self-alignment-interface::y-aligned-on-self
3799 -\tweak self-alignment-Y #-1 % move vertically up
3804 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3806 @c Cannot document as they do not seem to operate consistently on all objects -td
3807 @c TODO investigate further
3809 The @code{aligned-on-parent} procedures are used in the same way
3810 as the @code{aligned-on-self} procedures, they difference being
3811 that they permit an object to be aligned with the @emph{edges} of
3812 the parent rather than the parent's reference point. The following
3813 example shows the difference:
3817 @lilypond[verbatim,quote]
3823 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3825 @c Cannot document as they do not seem to operate consistently on all objects -td
3826 @c TODO investigate further
3830 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3832 @node Using the break-alignable-interface
3833 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3835 @cindex align to objects
3836 @cindex break-align-symbols
3838 Rehearsal marks and bar numbers may be aligned with notation
3839 objects other than bar lines. These objects include @code{ambitus},
3840 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3841 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3842 @code{time-signature}.
3844 Each type of object has its own default reference point, to which
3845 rehearsal marks are aligned:
3847 @lilypond[verbatim,quote,relative=1]
3848 % The rehearsal mark will be aligned to right edge of the Clef
3849 \override Score.RehearsalMark.break-align-symbols = #'(clef)
3854 % The rehearsal mark will be centered above the Time Signature
3855 \override Score.RehearsalMark.break-align-symbols = #'(time-signature)
3861 % The rehearsal mark will be centered above the Breath Mark
3862 \override Score.RehearsalMark.break-align-symbols = #'(breathing-sign)
3871 A list of possible target alignment objects may be specified. If
3872 some of the objects are invisible at that point due to the setting
3873 of @code{break-visibility} or the explicit visibility settings for
3874 keys and clefs, the rehearsal mark or bar number is aligned to the
3875 first object in the list which is visible. If no objects in the
3876 list are visible the object is aligned to the bar line. If the bar
3877 line is invisible the object is aligned to the place where the bar
3880 @lilypond[verbatim,quote,relative=1]
3881 % The rehearsal mark will be aligned to the right edge of the Key Signature
3882 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3887 % The rehearsal mark will be aligned to the right edge of the Clef
3888 \set Staff.explicitKeySignatureVisibility = #all-invisible
3889 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3894 % The rehearsal mark will be centered above the Bar Line
3895 \set Staff.explicitKeySignatureVisibility = #all-invisible
3896 \set Staff.explicitClefVisibility = #all-invisible
3897 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3904 The alignment of the rehearsal mark relative to the notation object
3905 can be changed, as shown in the following example. In a score with
3906 multiple staves, this setting should be done for all the staves.
3908 @lilypond[verbatim,quote,relative=1]
3909 % The RehearsalMark will be aligned with the right edge of the Key Signature
3910 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
3916 % The RehearsalMark will be centered above the Key Signature
3917 \once \override Score.KeySignature.break-align-anchor-alignment = #CENTER
3921 % The RehearsalMark will be aligned with the left edge of the Key Signature
3922 \once \override Score.KeySignature.break-align-anchor-alignment = #LEFT
3928 The rehearsal mark can also be offset to the right or left of the left
3929 edge by an arbitrary amount. The units are staff-spaces:
3931 @lilypond[verbatim,quote,relative=1]
3932 % The RehearsalMark will be aligned with the left edge of the Key Signature
3933 % and then shifted right by 3.5 staff-spaces
3934 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
3935 \once \override Score.KeySignature.break-align-anchor = #3.5
3939 % The RehearsalMark will be aligned with the left edge of the Key Signature
3940 % and then shifted left by 2 staff-spaces
3941 \once \override Score.KeySignature.break-align-anchor = #-2
3948 @node Vertical grouping of grobs
3949 @subsection Vertical grouping of grobs
3951 @c TODO Expand this section
3953 The VerticalAlignment and VerticalAxisGroup grobs work together.
3954 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3955 etc. VerticalAlignment then vertically aligns the different grobs
3956 grouped together by VerticalAxisGroup. There is usually only one
3957 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3961 @node Modifying stencils
3962 @subsection Modifying stencils
3964 All layout objects have a @code{stencil} property which is part of
3965 the @code{grob-interface}. By default, this property is usually
3966 set to a function specific to the object that is tailor-made to
3967 render the symbol which represents it in the output. For example,
3968 the standard setting for the @code{stencil} property of the
3969 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3971 The standard symbol for any object can be replaced by modifying the
3972 @code{stencil} property to reference a different, specially-written,
3973 procedure. This requires a high level of knowledge of the internal
3974 workings of LilyPond, but there is an easier way which can often
3975 produce adequate results.
3977 This is to set the @code{stencil} property to the procedure which
3978 prints text -- @code{ly:text-interface::print} -- and to add a
3979 @code{text} property to the object which is set to contain the
3980 markup text which produces the required symbol. Due to the
3981 flexibility of markup, much can be achieved -- see in particular
3982 @ref{Graphic notation inside markup}.
3984 The following example demonstrates this by changing the note head
3985 symbol to a cross within a circle.
3987 @lilypond[verbatim,quote]
3989 \once \override NoteHead.stencil = #ly:text-interface::print
3990 \once \override NoteHead.text = \markup {
3992 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3993 \musicglyph #"noteheads.s2cross"
4001 Any of the glyphs in the feta Font can be supplied to the
4002 @code{\musicglyph} markup command -- see @ref{The Feta font}.
4004 @c TODO Add inserting eps files or ref to later
4006 @c TODO Add inserting Postscript or ref to later
4010 @ref{Graphic notation inside markup},
4011 @ref{Formatting text},
4012 @ref{Text markup commands},
4013 @ref{The Feta font}.
4016 @node Modifying shapes
4017 @subsection Modifying shapes
4020 * Modifying ties and slurs::
4023 @node Modifying ties and slurs
4024 @unnumberedsubsubsec Modifying ties and slurs
4026 @cindex slurs, modifying
4027 @cindex ties, modifying
4028 @cindex Bézier curves, control points
4029 @cindex control points, Bézier curves
4031 @code{Tie}s, @code{Slur}s, @code{PhrasingSlur}s,
4032 @code{LaissezVibrerTie}s and @code{RepeatTie}s are all drawn as
4033 third-order Bézier curves. If the shape of the tie or slur which
4034 is calculated automatically is not optimum, the shape may be
4035 modified manually in two ways:
4039 by specifying the displacements to be made to the control points
4040 of the automatically calculated Bézier curve, or
4043 by explicitly specifying the positions of the four control points
4044 required to define the wanted curve.
4047 Both methods are explained below. The first method is more suitable
4048 if only slight adjustments to the curve are required; the second may
4049 be better for creating curves which are related to just a single
4052 @subsubsubheading Cubic Bézier curves
4054 Third-order or cubic Bézier curves are defined by four control
4055 points. The first and fourth control points are precisely the
4056 starting and ending points of the curve. The intermediate two
4057 control points define the shape. Animations showing how the curve
4058 is drawn can be found on the web, but the following description
4059 may be helpful. The curve starts from the first control point
4060 heading directly towards the second, gradually bending over to
4061 head towards the third and continuing to bend over to head towards
4062 the fourth, arriving there travelling directly from the third
4063 control point. The curve is entirely contained in the
4064 quadrilateral defined by the four control points. Translations,
4065 rotations and scaling of the control points all result in exactly
4066 the same operations on the curve.
4068 @subsubsubheading Specifying displacements from current control points
4070 @cindex shaping slurs and ties
4073 In this example the automatic placement of the tie is not optimum,
4074 and @code{\tieDown} would not help.
4076 @lilypond[verbatim,quote,relative=1]
4080 { r4 <g c,> <g c,> <g c,> }
4084 Adjusting the control points of the tie with @code{\shape} allows
4085 the collisions to be avoided.
4087 The syntax of @code{\shape} is
4090 [-]@code{\shape} @var{displacements} @var{item}
4093 This will reposition the control-points of @var{item} by the amounts
4094 given by @var{displacements}. The @var{displacements} argument is a
4095 list of number pairs or a list of such lists. Each element of a pair
4096 represents the displacement of one of the coordinates of a
4097 control-point. If @var{item} is a string, the result is
4098 @code{\once\override} for the specified grob type. If @var{item} is
4099 a music expression, the result is the same music expression with an
4100 appropriate tweak applied.
4102 In other words, the @code{\shape} function can act as either a
4103 @code{\once\override} command or a @code{\tweak} command depending
4104 on whether the @var{item} argument is a grob name, like @qq{Slur},
4105 or a music expression, like @qq{(}. The @var{displacements} argument
4106 specifies the displacements of the four control points as a list of
4107 four pairs of (dx . dy) values in units of staff-spaces (or a list
4108 of such lists if the curve has more than one segment).
4110 The leading hyphen is required if and only if the @code{\tweak} form
4113 So, using the same example as above and the @code{\once\override}
4114 form of @code{\shape}, this will raise the tie by half a staff-space:
4116 @lilypond[verbatim,quote,relative=1]
4119 \shape #'((0 . 0.5) (0 . 0.5) (0 . 0.5) (0 . 0.5)) Tie
4123 { r4 <g c,> <g c,> <g c,> }
4127 This positioning of the tie is better, but maybe it should be raised
4128 more in the center. The following example does this, this time using
4129 the alternative @code{\tweak} form:
4131 @lilypond[verbatim,quote,relative=1]
4134 e1-\shape #'((0 . 0.5) (0 . 1) (0 . 1) (0 . 0.5)) ~ e
4137 { r4 <g c,> <g c,> <g c,> }
4141 Changes to the horizontal positions of the control points may be made
4142 in the same way, and two different curves starting at the same
4143 musical moment may also be shaped:
4145 @lilypond[verbatim,quote,ragged-right,relative=2]
4147 \shape #'((0.7 . -0.4) (0.5 . -0.4) (0.3 . -0.3) (0 . -0.2)) Slur
4148 \shape #'((0 . 0) (0 . 0.5) (0 . 0.5) (0 . 0)) PhrasingSlur
4152 The @code{\shape} function can also displace the control points of
4153 curves which stretch across line breaks. Each piece of the broken
4154 curve can be given its own list of offsets. If changes to a
4155 particular segment are not needed, the empty list can serve as a
4156 placeholder. In this example the line break makes the single slur
4159 @lilypond[verbatim,quote,ragged-right,relative=1]
4165 Changing the shapes of the two halves of the slur makes it clearer
4166 that the slur continues over the line break:
4168 @lilypond[verbatim,quote,ragged-right,relative=1]
4169 % () may be used as a shorthand for ((0 . 0) (0 . 0) (0 . 0) (0 . 0))
4170 % if any of the segments does not need to be changed
4172 (( 0 . 0) (0 . 0) (0 . 0) (0 . 1))
4173 ((0.5 . 1.5) (1 . 0) (0 . 0) (0 . -1.5))
4180 If an S-shaped curve is required the control points must always be
4181 adjusted manually --- LilyPond will never select such shapes
4184 @lilypond[verbatim,quote,relative=2]
4185 c8( e b-> f d' a e-> g)
4186 \shape #'((0 . -1) (5.5 . -0.5) (-5.5 . -10.5) (0 . -5.5)) PhrasingSlur
4187 c8\( e b-> f d' a e-> g\)
4190 @subsubsubheading Specifying control points explicitly
4192 The coordinates of the Bézier control points are specified in units
4193 of staff-spaces. The X@tie{}coordinate is relative to the reference
4194 point of the note to which the tie or slur is attached, and the
4195 Y@tie{}coordinate is relative to the staff center line. The
4196 coordinates are specified as a list of four pairs of decimal numbers
4197 (reals). One approach is to estimate the coordinates of the two
4198 end points, and then guess the two intermediate points. The optimum
4199 values are then found by trial and error. Be aware that these values
4200 may need to be manually adjusted if any further changes are made to
4201 the music or the layout.
4203 One situation where specifying the control points explicitly is
4204 preferable to specifying displacements is when they need to be
4205 specified relative to a single note. Here is an example of this.
4206 It shows one way of indicating a slur extending into alternative
4207 sections of a volta repeat.
4209 @lilypond[verbatim,quote,relative=2]
4211 \repeat volta 3 { c4 d( e f }
4216 % create a slur and move it to a new position
4217 % the <> is just an empty chord to carry the slur termination
4218 -\tweak control-points #'((-2 . 3.8) (-1 . 3.9) (0 . 4) (1 . 3.4)) ( <> )
4223 % create a slur and move it to a new position
4224 -\tweak control-points #'((-2 . 3) (-1 . 3.1) (0 . 3.2) (1 . 2.4)) ( <> )
4231 It is not possible to modify shapes of ties or slurs by changing
4232 the @code{control-points} property if there are multiple ties or slurs
4233 at the same musical moment -- the @code{\tweak} command will also not
4234 work in this case. However, the @code{tie-configuration} property of
4235 @code{TieColumn} can be overridden to set start line and direction as
4239 Internals Reference:
4240 @rinternals{TieColumn}.
4243 @node Unpure-pure containers
4244 @subsection Unpure-pure containers
4246 @cindex Scheme, pure containers
4247 @cindex Scheme, unpure containers
4248 @cindex pure containers, Scheme
4249 @cindex unpure containers, Scheme
4250 @cindex horizontal spacing, overriding
4252 Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
4253 calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
4254 Scheme function instead of a literal (i.e. a number or pair).
4256 For certain grobs, the @code{Y-extent} is based on the @code{stencil}
4257 property, overriding the stencil property of one of these will
4258 require an additional @code{Y-extent} override with an unpure-pure
4259 container. When a function overrides a @code{Y-offset} and/or
4260 @code{Y-extent} it is assumed that this will trigger line breaking
4261 calculations too early during compilation. So the function is not
4262 evaluated at all (usually returning a value of @samp{0} or
4263 @samp{'(0 . 0)}) which can result in collisions. A @q{pure} function
4264 will not affect properties, objects or grob suicides and therefore will
4265 always have its Y-axis-related evaluated correctly.
4267 Currently, there are about thirty functions that are already considered
4268 @q{pure} and Unpure-pure containers are a way to set functions not on
4269 this list as @q{pure}. The @q{pure} function is evaluated @emph{before}
4270 any line-breaking and so the horizontal spacing can be adjusted
4271 @q{in time}. The @q{unpure} function is then evaluated @emph{after}
4274 @warning{As it is difficult to always know which functions are on this
4275 list we recommend that any @q{pure} functions you create do not use
4276 @code{Beam} or @code{VerticalAlignment} grobs.}
4278 An unpure-pure container is constructed as follows;
4280 @code{(ly:make-unpure-pure-container f0 f1)}
4282 where @code{f0} is a function taking @var{n} arguments (@var{n >= 1})
4283 and the first argument must always be the grob. This is the function
4284 that gives the actual result. @var{f1} is the function being labeled
4285 as @q{pure} that takes @var{n + 2} arguments. Again, the first argument
4286 must always still be the grob but the second and third are @q{start}
4287 and @q{end} arguments.
4289 @var{start} and @var{end} are, for all intents and purposes, dummy
4290 values that only matter for @code{Spanners} (i.e @code{Hairpin} or
4291 @code{Beam}), that can return different height estimations based on a
4292 starting and ending column.
4294 The rest are the other arguments to the first function (which
4295 may be none if @var{n = 1}).
4297 The results of the second function are used as an approximation of the
4298 value needed which is then used by the first function to get the real
4299 value which is then used for fine-tuning much later during the spacing
4302 @lilypond[verbatim,quote,ragged-right]
4303 #(define (square-line-circle-space grob)
4304 (let* ((pitch (ly:event-property (ly:grob-property grob 'cause) 'pitch))
4305 (notename (ly:pitch-notename pitch)))
4306 (if (= 0 (modulo notename 2))
4307 (make-circle-stencil 0.5 0.0 #t)
4308 (make-filled-box-stencil '(0 . 1.0)
4311 squareLineCircleSpace = {
4312 \override NoteHead.stencil = #square-line-circle-space
4315 smartSquareLineCircleSpace = {
4316 \squareLineCircleSpace
4317 \override NoteHead.Y-extent =
4318 #(ly:make-unpure-pure-container
4319 ly:grob::stencil-height
4320 (lambda (grob start end) (ly:grob::stencil-height grob)))
4323 \new Voice \with { \remove "Stem_engraver" }
4325 \squareLineCircleSpace
4327 \smartSquareLineCircleSpace
4332 In the first measure, without the unpure-pure container, the spacing
4333 engine does not know the width of the note head and lets it collide with
4334 the accidentals. In the second measure, with unpure-pure containers,
4335 the spacing engine knows the width of the note heads and avoids the
4336 collision by lengthening the line accordingly.
4338 Usually for simple calculations nearly-identical functions for both the
4339 @q{unpure} and @q{pure} parts can be used, by only changing the number
4340 of arguments passed to, and the scope of, the function.
4342 @warning{If a function is labeled as @q{pure} and it turns out not to
4343 be, the results can be unexpected.}
4346 @node Using music functions
4347 @section Using music functions
4349 @c TODO -- add @seealso, etc. to these subsections
4351 Where tweaks need to be reused with different music expressions,
4352 it is often convenient to make the tweak part of a @emph{music
4353 function}. In this section, we discuss only @emph{substitution}
4354 functions, where the object is to substitute a variable into a
4355 piece of LilyPond input code. Other more complex functions are
4356 described in @rextend{Music functions}.
4359 * Substitution function syntax::
4360 * Substitution function examples::
4363 @node Substitution function syntax
4364 @subsection Substitution function syntax
4366 Making a function that substitutes a variable into LilyPond
4367 code is easy. The general form of these functions is
4371 #(define-music-function
4372 (parser location @var{arg1} @var{arg2} @dots{})
4373 (@var{type1?} @var{type2?} @dots{})
4375 @var{@dots{}music@dots{}}
4382 @multitable @columnfractions .33 .66
4383 @item @code{@var{argN}}
4384 @tab @var{n}th argument
4386 @item @code{@var{typeN?}}
4387 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
4388 must return @code{#t}.
4390 @item @code{@var{@dots{}music@dots{}}}
4391 @tab normal LilyPond input, using @code{$} (in places where only
4392 Lilypond constructs are allowed) or @code{#} (to use it as a Scheme
4393 value or music function argument or music inside of music lists) to
4398 The @code{parser} and @code{location} arguments are mandatory, and
4399 are used in some advanced situations as described in the
4400 @q{Extending} manual (see @rextend{Music functions}). For
4401 substitution functions, just be sure to include them.
4403 The list of type predicates is also required. Some of the most
4404 common type predicates used in music functions are:
4408 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
4420 For a list of available type predicates, see
4421 @ref{Predefined type predicates}. User-defined type predicates
4426 @ref{Predefined type predicates}.
4429 @rextend{Music functions}.
4432 @file{lily/music-scheme.cc},
4434 @file{scm/lily.scm}.
4437 @node Substitution function examples
4438 @subsection Substitution function examples
4440 This section introduces some substitution function examples.
4441 These are not intended to be exhaustive, but rather to demonstrate
4442 some of the possibilities of simple substitution functions.
4444 In the first example, a function is defined that simplifies
4445 setting the padding of a TextScript:
4447 @lilypond[quote,verbatim,ragged-right]
4449 #(define-music-function
4450 (parser location padding)
4453 \once \override TextScript.padding = #padding
4457 c4^"piu mosso" b a b
4459 c4^"piu mosso" d e f
4461 c4^"piu mosso" fis a g
4465 In addition to numbers, we can use music expressions such
4466 as notes for arguments to music functions:
4468 @lilypond[quote,verbatim,ragged-right]
4470 #(define-music-function
4471 (parser location note)
4474 \tweak NoteHead.stencil #ly:text-interface::print
4475 \tweak NoteHead.text
4476 \markup \musicglyph #"custodes.mensural.u0"
4477 \tweak Stem.stencil ##f
4481 \relative c' { c4 d e f \custosNote g }
4484 Substitution functions with multiple arguments can be defined:
4486 @lilypond[quote,verbatim,ragged-right]
4488 #(define-music-function
4489 (parser location padding tempotext)
4492 \once \override Score.MetronomeMark.padding = #padding
4493 \tempo \markup { \bold #tempotext }
4497 \tempo \markup { "Low tempo" }
4499 \tempoPadded #4.0 "High tempo"
4504 @c TODO: add appropriate @@ref's here.