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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 * Output definitions - blueprints for contexts::
118 * Score - the master of all contexts::
119 * Top-level contexts - staff containers::
120 * Intermediate-level contexts - staves::
121 * Bottom-level contexts - voices::
124 @node Output definitions - blueprints for contexts
125 @unnumberedsubsubsec Output definitions - blueprints for contexts
127 This section explains the relevance of output definitions when
128 working with contexts. Examples for actual output definitions are
129 given later (see @ref{Changing all contexts of the same type}).
131 @cindex output definitions
133 While music written in a file may refer to context types and
134 names, contexts are created only when the music is actually being
135 interpreted. LilyPond interprets music under control of an
136 @q{output definition} and may do so for several different output
137 definitions, resulting in different output. The output definition
138 relevant for printing music is specified using @code{\layout}.
141 A much simpler output definition used for producing Midi output is
142 specified using @code{\midi}. Several other output definitions
143 are used by LilyPond internally, like when using the part combiner
144 (@ref{Automatic part combining}) or creating music quotes
145 (@ref{Quoting other voices}).
147 Output definitions define the relation between contexts as well as
148 their respective default settings. While most changes will
149 usually be made inside of a @code{\layout} block, Midi-related
150 settings will only have an effect when made within a @code{\midi}
153 @funindex autoBeaming
154 Some settings affect several outputs: for example, if
155 @code{autoBeaming} is turned off in some context, beams count as
156 melismata for the purpose of matching music to lyrics as described
157 in @ref{Automatic syllable durations}. This matching is done both
158 for printed output as well as for Midi. If changes made to
159 @code{autoBeaming} within a context definition of a @code{\layout}
160 block are not repeated in the corresponding @code{\midi} block,
161 lyrics and music will get out of sync in Midi.
165 @file{ly/engraver-init.ly}.
166 @file{ly/performer-init.ly}.
168 @node Score - the master of all contexts
169 @unnumberedsubsubsec Score - the master of all contexts
171 This is the top level notation context. No other context can
172 contain a Score context. By default the Score context handles
173 the administration of time signatures and makes sure that items
174 such as clefs, time signatures, and key-signatures are aligned
177 A Score context is instantiated implicitly when a
178 @code{\score @{@dots{}@}} block is processed.
180 @node Top-level contexts - staff containers
181 @unnumberedsubsubsec Top-level contexts - staff containers
183 @strong{@emph{StaffGroup}}
185 Groups staves while adding a bracket on the left side, grouping
186 the staves together. The bar lines of the contained staves are
187 connected vertically. @code{StaffGroup} only consists of a collection
188 of staves, with a bracket in front and spanning bar lines.
190 @strong{@emph{ChoirStaff}}
192 Identical to @code{StaffGroup} except that the bar lines of the
193 contained staves are not connected vertically.
195 @strong{@emph{GrandStaff}}
197 A group of staves, with a brace on the left side, grouping the
198 staves together. The bar lines of the contained staves are
199 connected vertically.
201 @strong{@emph{PianoStaff}}
203 Just like @code{GrandStaff}, but with support for instrument names
204 to the left of each system.
206 @node Intermediate-level contexts - staves
207 @unnumberedsubsubsec Intermediate-level contexts - staves
209 @strong{@emph{Staff}}
211 Handles clefs, bar lines, keys, accidentals. It can contain
212 @code{Voice} contexts.
214 @strong{@emph{RhythmicStaff}}
216 Like @code{Staff} but for printing rhythms. Pitches are ignored;
217 the notes are printed on one line.
219 @strong{@emph{TabStaff}}
221 Context for generating tablature. By default lays the music
222 expression out as a guitar tablature, printed on six lines.
224 @strong{@emph{DrumStaff}}
226 Handles typesetting for percussion. Can contain @code{DrumVoice}
228 @strong{@emph{VaticanaStaff}}
230 Same as @code{Staff}, except that it is designed for typesetting
231 a piece in gregorian style.
233 @strong{@emph{MensuralStaff}}
235 Same as @code{Staff}, except that it is designed for typesetting
236 a piece in mensural style.
238 @node Bottom-level contexts - voices
239 @unnumberedsubsubsec Bottom-level contexts - voices
241 Voice-level contexts initialise certain properties and start
242 appropriate engravers. A bottom-level context is one without
243 @code{defaultchild}. While it is possible to let it
244 accept/@/contain subcontexts, they can only be created and entered
247 @strong{@emph{Voice}}
249 Corresponds to a voice on a staff. This context handles the
250 conversion of dynamic signs, stems, beams, super- and sub-scripts,
251 slurs, ties, and rests. You have to instantiate this explicitly
252 if you require multiple voices on the same staff.
254 @strong{@emph{VaticanaVoice}}
256 Same as @code{Voice}, except that it is designed for typesetting
257 a piece in gregorian style.
259 @strong{@emph{MensuralVoice}}
261 Same as @code{Voice}, with modifications for typesetting a piece in
264 @strong{@emph{Lyrics}}
266 Corresponds to a voice with lyrics. Handles the printing of a
267 single line of lyrics.
269 @strong{@emph{DrumVoice}}
271 The voice context used in a percussion staff.
273 @strong{@emph{FiguredBass}}
275 The context in which @code{BassFigure} objects are created from
276 input entered in @code{\figuremode} mode.
278 @strong{@emph{TabVoice}}
280 The voice context used within a @code{TabStaff} context. Usually
281 left to be created implicitly.
283 @strong{@emph{CueVoice}}
285 A voice context used to render notes of a reduced size, intended
286 primarily for adding cue notes to a staff, see @ref{Formatting
287 cue notes}. Usually left to be created implicitly.
289 @strong{@emph{ChordNames}}
291 Typesets chord names.
296 Then the following, which I don't know what to do with:
298 * GregorianTranscriptionVoice
299 * GregorianTranscriptionStaff
302 Engraves fretboards from chords. Not easy... Not
304 There is now some documentation on FretBoards in the NR, under
305 instrument-specific notation -- cds.
310 Hard coded entry point for LilyPond. Cannot be tuned.
312 Silently discards all musical information given to this
317 @node Creating and referencing contexts
318 @subsection Creating and referencing contexts
323 @cindex referencing contexts
324 @cindex Contexts, creating and referencing
326 LilyPond will create lower-level contexts automatically if a music
327 expression is encountered before a suitable context exists, but this
328 is usually successful only for simple scores or music fragments like
329 the ones in the documentation. For more complex scores it is
330 advisable to specify all contexts explicitly with either the
331 @code{\new} or @code{\context} command. The syntax of
332 these two commands is very similar:
335 [\new | \context] @var{Context} [ = @var{name}] [@var{music-expression}]
339 where either @code{\new} or @code{\context} may be specified.
340 @var{Context} is the type of context which is to be created,
341 @var{name} is an optional name to be given to the particular context
342 being created and @var{music-expression} is a single music expression
343 that is to be interpreted by the engravers and performers in this
346 The @code{\new} prefix without a name is commonly used to create
347 scores with many staves:
349 @lilypond[quote,verbatim,relative=2]
352 % leave the Voice context to be created implicitly
362 and to place several voices into one staff:
364 @lilypond[quote,verbatim,relative=2]
380 @code{\new} should always be used to specify unnamed contexts.
382 The difference between @code{\new} and @code{\context} is in the
387 @code{\new} with or without a name will always create a fresh,
388 distinct, context, even if one with the same name already exists:
390 @lilypond[quote,verbatim,relative=2]
406 @code{\context} with a name specified will create a distinct context
407 only if a context of the same type with the same name in the same
408 context hierarchy does not already exist. Otherwise it will be taken
409 as a reference to that previously created context, and its music
410 expression will be passed to that context for interpretation.
412 One application of named contexts is in separating the score layout
413 from the musical content. Either of these two forms is valid:
415 @lilypond[quote,verbatim]
429 \context Voice = "one" {
434 \context Voice = "two" {
443 @lilypond[quote,verbatim]
448 \context Voice = "one" {
451 \context Voice = "two" {
457 \context Voice = "one" {
462 \context Voice = "two" {
472 Alternatively, variables may be employed to similar effect. See
473 @rlearning{Organizing pieces with variables}.
476 @code{\context} with no name will match the first of any previously
477 created contexts of the same type in the same context heirarchy,
478 even one that has been given a name, and its music expression will be
479 passed to that context for interpretation. This form is rarely
480 useful. However, @code{\context} with no name and no music expression
481 is used to set the context in which a Scheme procedure specified with
482 @code{\applyContext} is executed:
485 \new Staff \relative c' @{
488 \applyContext #(lambda (ctx)
490 (display (ly:context-current-moment ctx)))
497 A context must be named if it is to be referenced later, for example
498 when lyrics are associated with music:
501 \new Voice = "tenor" @var{music}
503 \new Lyrics \lyricsto "tenor" @var{lyrics}
507 For details of associating lyrics with music see
508 @ref{Automatic syllable durations}.
510 The properties of all contexts of a particular type can be modified
511 in a @code{\layout} block (with a different syntax), see
512 @ref{Changing all contexts of the same type}. This construct also
513 provides a means of keeping layout instructions separate from the
514 musical content. If a single context is to be modified, a @code{\with}
515 block must be used, see @ref{Changing just one specific context}.
519 @rlearning{Organizing pieces with variables}.
522 @ref{Changing just one specific context},
523 @ref{Automatic syllable durations}.
526 @node Keeping contexts alive
527 @subsection Keeping contexts alive
529 @cindex contexts, keeping alive
530 @cindex contexts, lifetime
532 Contexts are usually terminated at the first musical moment in
533 which they have nothing to do. So @code{Voice} contexts die as
534 soon as they contain no events; @code{Staff} contexts die as soon
535 as all the @code{Voice} contexts within them contain no events; etc.
536 This can cause difficulties if earlier contexts which have died
537 have to be referenced, for example, when changing staves with
538 @code{\change} commands, associating lyrics with a voice with
539 @code{\lyricsto} commands, or when adding further musical events to
542 There is an exception to this general rule: just one of the
543 @code{Voice} contexts in a @code{Staff} context or in a
544 @code{<<@dots{}>>} construct will always persist to the end of the
545 enclosing @code{Staff} context or @code{<<@dots{}>>} construct, even
546 though there may be periods when it has nothing to do. The context
547 to persist in this way will be the first one encountered in the
548 first enclosed @code{@{@dots{}@}} construct, ignoring any in enclosed
549 @code{<<@dots{}>>} constructs.
551 Any context can be kept alive by ensuring it has something to do at
552 every musical moment. @code{Staff} contexts are kept alive by
553 ensuring one of their voices is kept alive. One way of doing this
554 is to add spacer rests to a voice in parallel with the real music.
555 These need to be added to every @code{Voice} context which needs to
556 be kept alive. If several voices are to be used sporadically it is
557 safest to keep them all alive rather than attempting to rely on the
558 exceptions mentioned above.
560 In the following example, both voice A and voice B are kept alive
561 in this way for the duration of the piece:
563 @lilypond[quote,verbatim]
564 musicA = \relative c'' { d4 d d d }
565 musicB = \relative c'' { g4 g g g }
568 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
569 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
574 \context Voice = "A" {
578 \context Voice = "B" {
582 \context Voice = "A" { \musicA }
583 \context Voice = "B" { \musicB }
584 \context Voice = "A" { \musicA }
595 @cindex lyrics, aligning with sporadic melody
597 The following example shows how a sporadic melody line with lyrics
598 might be written using this approach. In a real situation the
599 melody and accompaniment would consist of several different
602 @lilypond[quote,verbatim]
603 melody = \relative c'' { a4 a a a }
604 accompaniment = \relative c' { d4 d d d }
605 words = \lyricmode { These words fol -- low the mel -- o -- dy }
608 \new Staff = "music" {
610 \new Voice = "melody" {
612 s1*4 % Keep Voice "melody" alive for 4 bars
615 \new Voice = "accompaniment" {
620 \context Voice = "melody" { \melody }
621 \context Voice = "accompaniment" { \accompaniment }
623 \context Voice = "accompaniment" { \accompaniment }
625 \context Voice = "melody" { \melody }
626 \context Voice = "accompaniment" { \accompaniment }
631 \new Lyrics \with { alignAboveContext = #"music" }
632 \lyricsto "melody" { \words }
637 An alternative way, which may be better in many circumstances, is
638 to keep the melody line alive by simply including spacer notes to
639 line it up correctly with the accompaniment:
641 @lilypond[quote,verbatim]
642 melody = \relative c'' {
648 accompaniment = \relative c' {
654 words = \lyricmode { These words fol -- low the mel -- o -- dy }
658 \new Staff = "music" {
660 \new Voice = "melody" {
664 \new Voice = "accompaniment" {
670 \new Lyrics \with { alignAboveContext = #"music" }
671 \lyricsto "melody" { \words }
677 @node Modifying context plug-ins
678 @subsection Modifying context plug-ins
680 @c TODO Should this be Modifying engravers or Modifying contexts?
682 Notation contexts (like @code{Score} and @code{Staff}) not only store
683 properties, they also contain plug-ins called @q{engravers} that create
684 notation elements. For example, the @code{Voice} context contains a
685 @code{Note_heads_engraver} and the @code{Staff} context contains a
688 For a full a description of each plug-in, see
690 @rinternals{Engravers and Performers}.
693 Internals Reference @expansion{} Translation @expansion{} Engravers.
695 Every context described in
697 @rinternals{Contexts}
700 Internals Reference @expansion{} Translation @expansion{} Context.
702 lists the engravers used for that context.
705 It can be useful to shuffle around these plug-ins. This is done by
706 starting a new context with @code{\new} or @code{\context}, and
712 \new @var{context} \with @{
720 @emph{@dots{}music@dots{}}
725 where the @dots{} should be the name of an engraver. Here is a simple
726 example which removes @code{Time_signature_engraver} and
727 @code{Clef_engraver} from a @code{Staff} context,
729 @lilypond[quote,relative=1,verbatim]
735 \remove "Time_signature_engraver"
736 \remove "Clef_engraver"
743 In the second staff there are no time signature or clef symbols. This
744 is a rather crude method of making objects disappear since it will affect
745 the entire staff. This method also influences the spacing, which may or
746 may not be desirable. More sophisticated methods of blanking objects
747 are shown in @rlearning{Visibility and color of objects}.
749 The next example shows a practical application. Bar lines and time
750 signatures are normally synchronized across the score. This is done
751 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
752 This plug-in keeps an administration of time signature, location
753 within the measure, etc. By moving these engraver from @code{Score} to
754 @code{Staff} context, we can have a score where each staff has its own
757 @cindex polymetric scores
758 @cindex Time signatures, multiple
760 @lilypond[quote,verbatim]
764 \consists "Timing_translator"
765 \consists "Default_bar_line_engraver"
772 \consists "Timing_translator"
773 \consists "Default_bar_line_engraver"
783 \remove "Timing_translator"
784 \remove "Default_bar_line_engraver"
792 The order in which the engravers are specified is the order in
793 which they are called to carry out their processing. Usually the
794 order in which the engravers are specified does not matter, but in
795 a few special cases the order is important, for example where one
796 engraver writes a property and another reads it, or where one
797 engraver creates a grob and another must process it.
799 The following orderings are important:
803 the @code{Bar_engraver} must normally be first,
806 the @code{New_fingering_engraver} must come before the
807 @code{Script_column_engraver},
810 the @code{Timing_translator} must come before the
811 @code{Bar_number_engraver}.
817 @file{ly/engraver-init.ly}.
820 @node Changing context default settings
821 @subsection Changing context default settings
823 @cindex default context properties, changing
824 @cindex context properties, changing defaults
826 Context and grob properties can be changed with @code{\set}
827 and @code{\override} commands, as described in
828 @ref{Modifying properties}. These commands create music events,
829 making the changes take effect at the point in time the music
832 In contrast, this section explains how to change the @emph{default}
833 values of context and grob properties at the time the context is
834 created. There are two ways of doing this. One modifies the default
835 values in all contexts of a particular type, the other modifies the
836 default values in just one particular instance of a context.
839 * Changing all contexts of the same type::
840 * Changing just one specific context::
841 * Order of precedence::
844 @node Changing all contexts of the same type
845 @unnumberedsubsubsec Changing all contexts of the same type
847 @cindex \context in \layout block
851 The default context settings which are to be used for typesetting in
852 @code{Score}, @code{Staff}, @code{Voice} and other contexts may be
853 specified in a @code{\context} block within any @code{\layout}
856 Settings for Midi output as opposed to typesetting will have to be
857 separately specified in @code{\midi} blocks (see @ref{Output
858 definitions - blueprints for contexts}).
860 The @code{\layout} block should be placed within the @code{\score}
861 block to which it is to apply, after the music.
867 [context settings for all Voice contexts]
871 [context settings for all Staff contexts]
876 The following types of settings may be specified:
880 An @code{\override} command, but with the context name omitted
882 @lilypond[quote,verbatim]
885 a4^"Thicker stems" a a a
891 \override Stem.thickness = #4.0
898 Directly setting a context property
900 @lilypond[quote,verbatim]
903 a4^"Smaller font" a a a
916 A predefined command such as @code{\dynamicUp} or a music
917 expression like @code{\accidentalStyle dodecaphonic}
919 @lilypond[quote,verbatim]
922 a4^"Dynamics above" a a a
932 \accidentalStyle dodecaphonic
939 A user-defined variable containing a @code{\with} block; for details
940 of the @code{\with} block see
941 @ref{Changing just one specific context}.
943 @lilypond[quote,verbatim]
944 StaffDefaults = \with {
951 a4^"Smaller font" a a a
966 Property-setting commands can be placed in a @code{\layout} block
967 without being enclosed in a @code{\context} block. Such settings
968 are equivalent to including the same property-setting commands at
969 the start of every context of the type specified. If no context
970 is specified @emph{every} bottom-level context is affected, see
971 @ref{Bottom-level contexts - voices}. The syntax of a
972 property-setting command in a @code{\layout} block is the same as
973 the same command written in the music stream.
975 @lilypond[quote,verbatim]
979 a4^"Smaller font" a a a
984 \accidentalStyle dodecaphonic
986 \override Voice.Stem.thickness = #4.0
992 @node Changing just one specific context
993 @unnumberedsubsubsec Changing just one specific context
998 The context properties of just one specific context instance can be
999 changed in a @code{\with} block. All other context instances of the
1000 same type retain the default settings built into LilyPond and modified
1001 by any @code{\layout} block within scope. The @code{\with} block
1002 must be placed immediately after the @code{\new} @var{context-type}
1006 \new Staff \with @{ [context settings for this context instance only] @}
1012 Since such a @q{context modification} is specified inside of
1013 music, it will affect @emph{all} outputs (typesetting @emph{and}
1014 Midi) as opposed to changes within an output definition.
1016 The following types of settings may be specified:
1020 An @code{\override} command, but with the context name omitted
1022 @lilypond[quote,verbatim]
1025 \new Voice \with { \override Stem.thickness = #4.0 }
1028 a4^"Thick stems" a a a
1037 Directly setting a context property
1039 @lilypond[quote,verbatim]
1044 a4^"Default font" a a a
1048 \new Staff \with { fontSize = #-4 }
1051 a4^"Smaller font" a a a
1060 A predefined command such as @code{\dynamicUp}
1062 @lilypond[quote,verbatim]
1068 a4^"Dynamics below" a a a
1073 \new Staff \with { \accidentalStyle dodecaphonic }
1075 \new Voice \with { \dynamicUp }
1078 a4^"Dynamics above" a a a
1089 @node Order of precedence
1090 @unnumberedsubsubsec Order of precedence
1092 The value of a property which applies at a particular time is
1093 determined as follows:
1097 if an @code{\override} or @code{\set} command in the input stream is
1098 in effect that value is used,
1101 otherwise the default value taken from a @code{\with} statement
1102 on the context initiation statement is used,
1105 otherwise the default value taken from the most recent appropriate
1106 @code{\context} block in the @code{\layout} or @code{\midi} blocks
1110 otherwise the LilyPond built-in default is used.
1115 @rlearning{Modifying context properties}.
1118 @ref{Contexts explained},
1119 @ref{Bottom-level contexts - voices},
1120 @ref{The set command},
1121 @ref{The override command},
1122 @ref{The layout block,,The @code{@bs{}layout} block}.
1125 @node Defining new contexts
1126 @subsection Defining new contexts
1128 @cindex contexts, defining new
1129 @cindex engravers, including in contexts
1144 Specific contexts, like @code{Staff} and @code{Voice}, are made from
1145 simple building blocks. It is possible to create new types of
1146 contexts with different combinations of engraver plug-ins.
1148 The next example shows how to build a different type of
1149 @code{Voice} context from scratch. It will be similar to
1150 @code{Voice}, but only prints centered slash note heads. It can be used
1151 to indicate improvisation in jazz pieces,
1153 @lilypond[quote,ragged-right]
1154 \layout { \context {
1156 \type "Engraver_group"
1157 \consists "Note_heads_engraver"
1158 \consists "Rhythmic_column_engraver"
1159 \consists "Text_engraver"
1160 \consists "Pitch_squash_engraver"
1161 squashedPosition = #0
1162 \override NoteHead.style = #'slash
1167 \accepts "ImproVoice"
1171 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1172 c4 c^"undress" c_"while playing :)" c }
1178 These settings are defined within a @code{\context} block inside a
1179 @code{\layout} block,
1189 In the following discussion, the example input shown should go in place
1190 of the @dots{} in the previous fragment.
1192 First it is necessary to define a name for the new context:
1198 Since it is similar to the @code{Voice} context, we want commands that
1199 work in (existing) @code{Voice} contexts to continue working. This is
1200 achieved by giving the new context an alias of @code{Voice},
1206 The context will print notes and instructive texts, so we need to add
1207 the engravers which provide this functionality, plus the engraver which
1208 groups notes, stems and rests which occur at the same musical moment
1212 \consists "Note_heads_engraver"
1213 \consists "Text_engraver"
1214 \consists "Rhythmic_column_engraver"
1217 The note heads should all be placed on the center line,
1220 \consists "Pitch_squash_engraver"
1221 squashedPosition = #0
1224 The @code{Pitch_squash_engraver} modifies note heads (created
1225 by the @code{Note_heads_engraver}) and sets their vertical
1226 position to the value of @code{squashedPosition}, in this
1227 case@tie{}@code{0}, the center line.
1229 The notes look like a slash, and have no stem,
1232 \override NoteHead.style = #'slash
1236 All these plug-ins have to communicate under the control of the
1237 context. The mechanisms with which contexts communicate are
1238 established by declaring the context @code{\type}. Within a
1239 @code{\layout} block, most contexts will be of type
1240 @code{Engraver_group}. Some special contexts and contexts in
1241 @code{\midi} blocks use other context types. Copying and
1242 modifying an existing context definition will also fill in the
1243 type. Since this example creates a definition from scratch, it
1244 needs to be specified explicitly.
1247 \type "Engraver_group"
1250 Put together, we get
1255 \type "Engraver_group"
1256 \consists "Note_heads_engraver"
1257 \consists "Text_engraver"
1258 \consists "Rhythmic_column_engraver"
1259 \consists "Pitch_squash_engraver"
1260 squashedPosition = #0
1261 \override NoteHead.style = #'slash
1268 Contexts form hierarchies. We want to place the @code{ImproVoice}
1269 context within the @code{Staff} context, just like normal @code{Voice}
1270 contexts. Therefore, we modify the @code{Staff} definition with the
1271 @code{\accepts} command,
1281 The opposite of @code{\accepts} is @code{\denies},
1282 which is sometimes needed when reusing existing context definitions.
1284 Putting both into a @code{\layout} block, like
1294 \accepts "ImproVoice"
1299 Then the output at the start of this subsection can be entered as
1307 c c_"while playing :)"
1313 To complete this example, changes affecting the context hierarchy
1314 should be repeated in a @code{\midi} block so that Midi output
1315 depends on the same context relations.
1319 Internals Reference:
1320 @rinternals{Engraver_group},
1321 @rinternals{Note_heads_engraver},
1322 @rinternals{Text_engraver},
1323 @rinternals{Rhythmic_column_engraver},
1324 @rinternals{Pitch_squash_engraver}.
1327 @node Context layout order
1328 @subsection Context layout order
1330 @cindex contexts, layout order
1334 Contexts are normally positioned in a system from top to bottom
1335 in the order in which they are encountered in the input file. When
1336 contexts are nested, the outer context will include inner nested
1337 contexts as specified in the input file, provided the inner contexts
1338 are included in the outer context's @qq{accepts} list. Nested
1339 contexts which are not included in the outer context's @qq{accepts}
1340 list will be repositioned below the outer context rather than nested
1343 The @qq{accepts} list of a context can be changed with the
1344 @code{\accepts} and @code{\denies} commands. @code{\accepts} adds a
1345 context to the @qq{accepts} list and @code{\denies} removes a context
1346 from the list. For example, it would not normally be desirable for
1347 chord names to be nested within a @code{Staff} context, so the
1348 @code{ChordNames} context is not included by default in the @qq{accepts}
1349 list of the @code{Staff} context, but if this were to be required it can
1352 @lilypond[verbatim,quote]
1356 \chords { d1:m7 b1:min7.5- }
1361 @lilypond[verbatim,quote]
1365 \chords { d1:m7 b1:min7.5- }
1370 \accepts "ChordNames"
1376 @code{\denies} is mainly used when a new context is being based on
1377 another, but the required nesting differs. For example, the
1378 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1379 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1380 context in the @qq{accepts} list.
1382 @cindex contexts, implicit
1383 @cindex implicit contexts
1384 @funindex \defaultchild
1386 Note that a context will be silently created implicitly if a
1387 command is encountered when there is no suitable context available
1390 Within a context definition, the type of subcontext to be
1391 implicitly created is specified using @code{\defaultchild}. A
1392 number of music events require a @samp{Bottom} context: when such
1393 an event is encountered, subcontexts are created recursively until
1394 reaching a context with no @samp{defaultchild} setting.
1396 Implicit context creation can at times give rise to unexpected new
1397 staves or scores. Using @code{\new} to create contexts explicitly
1398 avoids those problems.
1400 @cindex alignAboveContext
1401 @cindex alignBelowContext
1402 @funindex alignAboveContext
1403 @funindex alignBelowContext
1405 Sometimes a context is required to exist for just a brief period, a
1406 good example being the staff context for an ossia. This is usually
1407 achieved by introducing the context definition at the appropriate
1408 place in parallel with corresponding section of the main music.
1409 By default, the temporary context will be placed below all the
1410 existing contexts. To reposition it above the context called
1411 @qq{main}, it should be defined like this:
1414 @code{\new Staff \with @{ alignAboveContext = #"main" @} }
1417 A similar situation arises when positioning a temporary lyrics
1418 context within a multi-staved layout such as a @code{ChoirStaff},
1419 for example, when adding a second verse to a repeated section.
1420 By default the temporary lyrics context will be placed beneath the
1421 lower staves. By defining the temporary lyrics context with
1422 @code{alignBelowContext} it can be positioned correctly beneath
1423 the (named) lyrics context containing the first verse.
1425 Examples showing this repositioning of temporary contexts can be
1426 found elsewhere --- see @rlearning{Nesting music expressions},
1427 @ref{Modifying single staves} and @ref{Techniques specific to lyrics}.
1431 @rlearning{Nesting music expressions}.
1434 @ref{Modifying single staves},
1435 @ref{Techniques specific to lyrics}.
1438 @rprogram{An extra staff appears}.
1441 @file{ly/engraver-init.ly}.
1444 @node Explaining the Internals Reference
1445 @section Explaining the Internals Reference
1448 * Navigating the program reference::
1449 * Layout interfaces::
1450 * Determining the grob property::
1451 * Naming conventions::
1454 @node Navigating the program reference
1455 @subsection Navigating the program reference
1457 @c TODO remove this (it's in the LM)
1458 @c Replace with more factual directions
1460 Suppose we want to move the fingering indication in the fragment
1463 @lilypond[quote,relative=2,verbatim]
1469 If you visit the documentation on fingering instructions (in
1470 @ref{Fingering instructions}), you will notice:
1475 Internals Reference: @rinternals{Fingering}.
1480 @c outdated info; probably will delete.
1482 This fragment points to two parts of the program reference: a page
1483 on @code{FingeringEvent} and one on @code{Fingering}.
1485 The page on @code{FingeringEvent} describes the properties of the music
1486 expression for the input @w{@code{-2}}. The page contains many links
1487 forward. For example, it says
1490 Accepted by: @rinternals{Fingering_engraver},
1494 That link brings us to the documentation for the Engraver, the
1498 This engraver creates the following layout objects: @rinternals{Fingering}.
1501 In other words, once the @code{FingeringEvent}s are interpreted, the
1502 @code{Fingering_engraver} plug-in will process them.
1506 @c I can't figure out what this is supposed to mean. -gp
1508 The @code{Fingering_engraver} is also listed to create
1509 @rinternals{Fingering} objects,
1511 @c old info? it doesn't make any sense to me with our current docs.
1513 second bit of information listed under @b{See also} in the Notation
1518 The programmer's reference is available as an HTML document. It is
1519 highly recommended that you read it in HTML form, either online or
1520 by downloading the HTML documentation. This section will be much more
1521 difficult to understand if you are using the
1525 Follow the link to @rinternals{Fingering}. At the top of the
1529 Fingering objects are created by: @rinternals{Fingering_engraver} and
1530 @rinternals{New_fingering_engraver}.
1533 By following related links inside the program reference, we can follow the
1534 flow of information within the program:
1538 @item @rinternals{Fingering}:
1539 @rinternals{Fingering} objects are created by:
1540 @rinternals{Fingering_engraver}
1542 @item @rinternals{Fingering_engraver}:
1543 Music types accepted: @rinternals{fingering-event}
1545 @item @rinternals{fingering-event}:
1546 Music event type @code{fingering-event} is in Music expressions named
1547 @rinternals{FingeringEvent}
1550 This path goes against the flow of information in the program: it
1551 starts from the output, and ends at the input event. You could
1552 also start at an input event, and read with the flow of
1553 information, eventually ending up at the output object(s).
1555 The program reference can also be browsed like a normal document. It
1556 contains chapters on
1558 @rinternals{Music definitions},
1561 @code{Music definitions}
1563 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1564 chapter lists all the definitions used and all properties that may be
1568 @node Layout interfaces
1569 @subsection Layout interfaces
1571 @cindex interface, layout
1572 @cindex layout interface
1575 The HTML page that we found in the previous section describes the
1576 layout object called @rinternals{Fingering}. Such an object is a
1577 symbol within the score. It has properties that store numbers (like
1578 thicknesses and directions), but also pointers to related objects. A
1579 layout object is also called a @emph{Grob}, which is short for Graphical
1580 Object. For more details about Grobs, see @rinternals{grob-interface}.
1582 The page for @code{Fingering} lists the definitions for the
1583 @code{Fingering} object. For example, the page says
1586 @code{padding} (dimension, in staff space):
1592 which means that the number will be kept at a distance of at least 0.5
1596 Each layout object may have several functions as a notational or
1597 typographical element. For example, the Fingering object
1598 has the following aspects
1602 Its size is independent of the horizontal spacing, unlike slurs or beams.
1605 It is a piece of text. Granted, it is usually a very short text.
1608 That piece of text is typeset with a font, unlike slurs or beams.
1611 Horizontally, the center of the symbol should be aligned to the
1612 center of the note head.
1615 Vertically, the symbol is placed next to the note and the staff.
1618 The vertical position is also coordinated with other superscript
1619 and subscript symbols.
1622 Each of these aspects is captured in so-called @emph{interface}s,
1623 which are listed on the @rinternals{Fingering} page at the bottom
1626 This object supports the following interfaces:
1627 @rinternals{item-interface},
1628 @rinternals{self-alignment-interface},
1629 @rinternals{side-position-interface}, @rinternals{text-interface},
1630 @rinternals{text-script-interface}, @rinternals{font-interface},
1631 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1634 Clicking any of the links will take you to the page of the respective
1635 object interface. Each interface has a number of properties. Some of
1636 them are not user-serviceable (@q{Internal properties}), but others
1639 We have been talking of @emph{the} @code{Fingering} object, but actually it
1640 does not amount to much. The initialization file (see
1641 @rlearning{Other sources of information})
1642 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1647 (avoid-slur . around)
1648 (slur-padding . 0.2)
1649 (staff-padding . 0.5)
1650 (self-alignment-X . 0)
1651 (self-alignment-Y . 0)
1652 (script-priority . 100)
1653 (stencil . ,ly:text-interface::print)
1654 (direction . ,ly:script-interface::calc-direction)
1655 (font-encoding . fetaText)
1656 (font-size . -5) ; don't overlap when next to heads.
1657 (meta . ((class . Item)
1658 (interfaces . (finger-interface
1660 text-script-interface
1662 side-position-interface
1663 self-alignment-interface
1664 item-interface))))))
1668 As you can see, the @code{Fingering} object is nothing more than a
1669 bunch of variable settings, and the webpage in the Internals Reference
1670 is directly generated from this definition.
1673 @node Determining the grob property
1674 @subsection Determining the grob property
1676 @c TODO remove this (it's in the LM)
1677 @c Replace with more factual directions
1679 Recall that we wanted to change the position of the @b{2} in
1681 @lilypond[quote,relative=2,verbatim]
1687 Since the @b{2} is vertically positioned next to its note, we have to
1688 meddle with the interface associated with this positioning. This is
1689 done using @code{side-position-interface}. The page for this interface
1693 @code{side-position-interface}
1695 Position a victim object (this one) next to other objects (the
1696 support). The property @code{direction} signifies where to put the
1697 victim object relative to the support (left or right, up or down?)
1702 Below this description, the variable @code{padding} is described as
1707 (dimension, in staff space)
1709 Add this much extra space between objects that are next to each other.
1713 By increasing the value of @code{padding}, we can move the
1714 fingering away from the note head. The following command inserts
1715 3 staff spaces of white
1716 between the note and the fingering:
1718 \once \override Voice.Fingering.padding = #3
1721 Inserting this command before the Fingering object is created,
1722 i.e., before @code{c2}, yields the following result:
1724 @lilypond[quote,relative=2,verbatim]
1725 \once \override Voice.Fingering.padding = #3
1732 In this case, the context for this tweak is @code{Voice}. This
1733 fact can also be deduced from the program reference, for the page for
1734 the @rinternals{Fingering_engraver} plug-in says
1737 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1741 @node Naming conventions
1742 @subsection Naming conventions
1744 Another thing that is needed, is an overview of the various naming
1748 @item scheme functions: lowercase-with-hyphens (incl. one-word
1750 @item scheme functions: ly:plus-scheme-style
1751 @item music events, music classes and music properties:
1753 @item Grob interfaces: scheme-style
1754 @item backend properties: scheme-style (but X and Y!)
1755 @item contexts (and MusicExpressions and grobs): Capitalized or
1757 @item context properties: lowercaseFollowedByCamelCase
1759 Capitalized_followed_by_lowercase_and_with_underscores
1762 Questions to be answered:
1764 @item Which of these are conventions and which are rules?
1765 @item Which are rules of the underlying language, and which are
1769 @node Modifying properties
1770 @section Modifying properties
1772 @c TODO change the menu and subsection node names to use
1773 @c backslash once the new macro to handle the refs
1774 @c is available. Need to find and change all refs at
1775 @c the same time. -td
1778 * Overview of modifying properties::
1780 * The override command::
1781 * The tweak command::
1782 * set versus override::
1783 * Modifying alists::
1787 @node Overview of modifying properties
1788 @subsection Overview of modifying properties
1790 Each context is responsible for creating certain types of graphical
1791 objects. The settings used for printing these objects are also stored by
1792 context. By changing these settings, the appearance of objects can be
1795 There are two different kinds of properties stored in contexts:
1796 context properties and grob properties. Context properties are
1797 properties that apply to the context as a whole and control
1798 how the context itself is displayed. In contrast, grob properties
1799 apply to specific grob types that will be displayed in the context.
1801 The @code{\set} and @code{\unset} commands are used to change values
1802 for context properties. The @code{\override} and @code{\revert}
1803 commands are used to change values for grob properties.
1806 The syntax for this is
1809 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1812 Here @var{name} is the name of a graphical object, like
1813 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1814 variable of the formatting system (@q{grob property} or @q{layout
1815 property}). The latter is a symbol, so it must be quoted. The
1816 subsection @ref{Modifying properties}, explains what to fill in
1817 for @var{name}, @var{property}, and @var{value}. Here we only
1818 discuss the functionality of this command.
1823 \override Staff.Stem.thickness = #4.0
1827 makes stems thicker (the default is 1.3, with staff line thickness as a
1828 unit). Since the command specifies @code{Staff} as context, it only
1829 applies to the current staff. Other staves will keep their normal
1830 appearance. Here we see the command in action:
1832 @lilypond[quote,verbatim,relative=2]
1834 \override Staff.Stem.thickness = #4.0
1840 The @code{\override} command changes the definition of the @code{Stem}
1841 within the current @code{Staff}. After the command is interpreted
1842 all stems are thickened.
1844 Analogous to @code{\set}, the @var{context} argument may be left out,
1845 causing the default context @code{Voice} to be used. Adding
1846 @code{\once} applies the change during one timestep only.
1848 @lilypond[quote,verbatim,relative=2]
1850 \once \override Stem.thickness = #4.0
1855 The @code{\override} must be done before the object is
1856 started. Therefore, when altering @emph{Spanner} objects such as slurs
1857 or beams, the @code{\override} command must be executed at the moment
1858 when the object is created. In this example,
1860 @lilypond[quote,verbatim,relative=2]
1861 \override Slur.thickness = #3.0
1863 \override Beam.beam-thickness = #0.6
1868 the slur is fatter but the beam is not. This is because the command for
1869 @code{Beam} comes after the Beam is started, so it has no effect.
1871 Analogous to @code{\unset}, the @code{\revert} command for a context
1872 undoes an @code{\override} command; like with @code{\unset}, it only
1873 affects settings that were made in the same context. In other words, the
1874 @code{\revert} in the next example does not do anything.
1877 \override Voice.Stem.thickness = #4.0
1878 \revert Staff.Stem.thickness
1881 Some tweakable options are called @q{subproperties} and reside inside
1882 properties. To tweak those, use commands of the form
1884 @c leave this as a long long
1886 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1893 \override Stem.details.beamed-lengths = #'(4 4 3)
1899 Internals Reference:
1900 @rinternals{Backend},
1901 @rinternals{All layout objects},
1902 @rinternals{OverrideProperty},
1903 @rinternals{RevertProperty},
1904 @rinternals{PropertySet}.
1907 The back-end is not very strict in type-checking object properties.
1908 Cyclic references in Scheme values for properties can cause hangs
1909 or crashes, or both.
1912 @node The set command
1913 @subsection The @code{@bs{}set} command
1917 @cindex changing properties
1919 Each context has a set of @emph{properties}, variables contained
1920 in that context. Context properties are changed with the @code{\set}
1921 command, which has the following syntax:
1924 \set @var{context}.@var{property} = #@var{value}
1927 @var{value} is a Scheme object, which is why it must be preceded by
1928 the @code{#}@tie{}character.
1930 Contexts properties are usually named in
1931 @code{studlyCaps}. They mostly control the translation from
1932 music to notation, e.g. @code{localKeySignature} (for determining
1933 whether to print accidentals), or @code{measurePosition} (for
1934 determining when to print a bar line). Context properties can
1935 change value over time while interpreting a piece of music;
1936 @code{measurePosition} is an obvious example of
1937 this. Context properties are modified with @code{\set}.
1939 For example, multimeasure rests will be combined into a single bar
1940 if the context property @code{skipBars} is set to @code{#t}:
1942 @lilypond[quote,verbatim,relative=2]
1944 \set Score.skipBars = ##t
1948 If the @var{context} argument is left out, then the property will be
1949 set in the current bottom context (typically @code{ChordNames},
1950 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1952 @lilypond[quote,verbatim,relative=2]
1953 \set Score.autoBeaming = ##f
1957 \set autoBeaming = ##t
1965 The change is applied @q{on-the-fly}, during the music, so that the
1966 setting only affects the second group of eighth notes.
1968 Note that the bottom-most context does not always contain the property
1969 that you wish to change -- for example, attempting to set the
1970 @code{skipBars} property of the default bottom context, in this case
1971 @code{Voice}, will have no effect, because skipBars is a property of
1972 the @code{Score} context.
1974 @lilypond[quote,verbatim,relative=2]
1980 Contexts are hierarchical, so if an enclosing context was specified, for
1981 example @code{Staff}, then the change would also apply to all
1982 @code{Voice}s in the current staff.
1986 The @code{\unset} command:
1989 \unset @var{context}.@var{property}
1993 is used to remove the definition of @var{property} from
1994 @var{context}. This command removes
1995 the definition only if it is set in @var{context}.
1996 Properties that have been set in enclosing contexts will
1997 not be altered by an unset in an enclosed context:
1999 @lilypond[quote,verbatim,relative=2]
2000 \set Score.autoBeaming = ##t
2005 \unset Score.autoBeaming
2013 Like @code{\set}, the @var{context} argument does not have to be
2014 specified for a bottom context, so the two statements
2017 \set Voice.autoBeaming = ##t
2018 \set autoBeaming = ##t
2022 are equivalent if the current bottom context is @code{Voice}.
2026 Preceding a @code{\set} command by @code{\once} makes the
2027 setting apply to only a single time-step:
2029 @lilypond[quote,verbatim,relative=2]
2031 \once \set fontSize = #4.7
2036 A full description of all available context properties is in the
2037 internals reference, see
2039 @rinternals{Tunable context properties}.
2042 Translation @expansion{} Tunable context properties.
2046 Internals Reference:
2047 @rinternals{Tunable context properties}.
2050 @node The override command
2051 @subsection The @code{\override} command
2053 @cindex grob properties
2054 @cindex properties, grob
2057 There is a special type of context property: the grob
2058 description. Grob descriptions are named in @code{StudlyCaps}
2059 (starting with capital letters). They contain the
2060 @q{default settings} for a particular kind of grob as an
2061 association list. See @file{scm/define-grobs.scm}
2062 to see the settings for each grob description. Grob descriptions
2063 are modified with @code{\override}.
2065 The syntax for the @code{\override} command is
2068 \override [@var{context}.]@var{GrobName}.@var{property} = #@var{value}
2071 For example, we can increase the thickness of a note stem by
2072 overriding the @code{thickness} property of the @code{Stem}
2075 @lilypond[quote,verbatim,relative=2]
2077 \override Voice.Stem.thickness = #3.0
2081 If no context is specified in an @code{\override}, the bottom
2084 @lilypond[quote,verbatim,relative=2]
2085 { \override Staff.Stem.thickness = #3.0
2089 \override Stem.thickness = #0.5
2098 Some tweakable options are called @q{subproperties} and reside inside
2099 properties. To tweak those, use commands in the form
2102 \override Stem.details.beamed-lengths = #'(4 4 3)
2105 or to modify the ends of spanners, use a form like these
2108 \override TextSpanner.bound-details.left.text = #"left text"
2109 \override TextSpanner.bound-details.right.text = #"right text"
2113 @cindex reverting overrides
2114 @cindex overrides, reverting
2116 The effects of @code{\override} can be undone by @code{\revert}.
2118 The syntax for the @code{\revert} command is
2121 \revert [@var{context}.]@var{GrobName}.@var{property}
2126 @lilypond[quote,verbatim,relative=2]
2128 \override Voice.Stem.thickness = #3.0
2130 \revert Voice.Stem.thickness
2134 The effects of @code{\override} and @code{\revert} apply to all
2135 grobs in the affected context from the current time forward:
2137 @lilypond[quote,verbatim,relative=2]
2142 \override Staff.Stem.thickness = #3.0
2146 \revert Staff.Stem.thickness
2154 @cindex overriding for only one moment
2156 @code{\once} can be used with @code{\override}
2157 to affect only the current time step:
2159 @lilypond[quote,verbatim,relative=2]
2163 \override Stem.thickness = #3.0
2167 \once \override Stem.thickness = #3.0
2176 Commands which change output generally look like
2179 \override Voice.Stem.thickness = #3.0
2183 To construct this tweak we must determine these bits of information:
2186 @item the context: here @code{Voice}.
2187 @item the layout object: here @code{Stem}.
2188 @item the layout property: here @code{thickness}.
2189 @item a sensible value: here @code{3.0}.
2192 @cindex internal documentation
2193 @cindex finding graphical objects
2194 @cindex graphical object descriptions
2197 @cindex internal documentation
2199 For many properties, regardless of the data type of the property, setting the
2200 property to false (@code{#f}) will result in turning it off, causing
2201 LilyPond to ignore that property entirely. This is particularly useful for
2202 turning off grob properties which may otherwise be causing problems.
2204 We demonstrate how to glean this information from the notation manual
2205 and the program reference.
2209 Internals Reference:
2210 @rinternals{Backend}
2213 @node The tweak command
2214 @subsection The @code{\tweak} command
2219 Changing grob properties
2220 with @code{\override} causes the changes to apply to all of the
2221 given grobs in the context at the moment the change applies.
2222 Sometimes, however, it is desirable to have changes apply to just
2223 one grob, rather than to all grobs in the affected context. This is
2224 accomplished with the @code{\tweak} command, which has the following
2228 \tweak [@var{layout-object}.]@var{grob-property} @var{value}
2231 Specifying @var{layout-object} is optional.
2232 The @code{\tweak} command applies to the music object that immediately
2233 follows @var{value} in the music stream.
2236 In some cases, it is possible to take a short-cut for tuning
2237 graphical objects. For objects that are created directly from
2238 an item in the input file, you can use the @code{\tweak} command.
2241 @lilypond[relative=2,verbatim,quote]
2246 \tweak duration-log #1
2255 The main use of the @code{\tweak} command is to modify just
2256 one of a number of notation elements which start at the same musical
2257 moment, like the notes of a chord, or tuplet brackets which start
2260 The @code{\tweak} command sets a property in the following object
2261 directly, without requiring the grob name or context to be
2262 specified. For this to work, it is necessary for the @code{\tweak}
2263 command to remain immediately adjacent to the object to which it is
2264 to apply after the input file has been converted to a music stream.
2265 This is often not the case, as many additional elements are inserted
2266 into the music stream implicitly. For example, when a note which is
2267 not part of a chord is processed, LilyPond implicitly inserts a
2268 @code{ChordEvent} event before the note, so separating the tweak
2269 from the note. However, if chord symbols are placed round the
2270 tweak and the note, the @code{\tweak} command comes after the
2271 @code{ChordEvent} in the music stream, so remaining adjacent to the
2272 note, and able to modify it.
2276 @lilypond[relative=2,verbatim,quote]
2277 <\tweak color #red c>4
2283 @lilypond[relative=2,verbatim,quote]
2284 \tweak color #red c4
2289 For an introduction to the syntax and uses of the tweak command
2290 see @rlearning{Tweaking methods}.
2292 When several similar items are placed at the same musical moment,
2293 the @code{\override} command cannot be used to modify just one of
2294 them -- this is where the @code{\tweak} command must be used.
2295 Items which may appear more than once at the same musical moment
2296 include the following:
2298 @c TODO expand to include any further uses of \tweak
2300 @item note heads of notes inside a chord
2301 @item articulation signs on a single note
2302 @item ties between notes in a chord
2303 @item tuplet brackets starting at the same time
2306 @c TODO add examples of these
2308 @cindex chord, modifying one note in
2310 In this example, the color of one note head and the type of another
2311 note head are modified within a single chord:
2313 @lilypond[relative=2,verbatim,quote]
2318 \tweak duration-log #1
2323 @code{\tweak} can be used to modify slurs:
2325 @lilypond[verbatim,quote,relative=1]
2326 c-\tweak thickness #5 ( d e f)
2330 For the @code{\tweak} command to work, it must
2331 remain immediately adjacent to the object to which it is
2332 to apply after the input file has been converted to a music stream.
2333 Tweaking a whole chord does not do anything since its music event
2334 only acts as a container, and all layout objects are created from events
2335 inside of the @code{EventChord}:
2337 @lilypond[relative=2,verbatim,quote]
2338 \tweak color #red c4
2339 \tweak color #red <c e>4
2340 <\tweak color #red c e>4
2343 The simple @code{\tweak} command cannot be used to modify any object
2344 that is not directly created from the input. In particular
2345 it will not affect stems, automatic
2346 beams or accidentals, since these are generated later by
2347 @code{NoteHead} layout objects rather than by music elements in the
2350 Such indirectly created layout objects can be tweaked using the form
2351 of the @code{\tweak} command in which the grob name is specified
2354 @lilypond[relative=2,verbatim,quote]
2355 \tweak Stem.color #red
2356 \tweak Beam.color #green c8 e
2357 <c e \tweak Accidental.font-size #-3 ges>4
2360 @code{\tweak} cannot be used to modify clefs or time
2361 signatures, since these become separated from any preceding
2362 @code{\tweak} command in the input stream by the automatic
2363 insertion of extra elements required to specify the context.
2365 Several @code{\tweak} commands may be placed before a
2366 notational element -- all affect it:
2368 @lilypond[verbatim,quote,relative=1]
2370 -\tweak style #'dashed-line
2371 -\tweak dash-fraction #0.2
2372 -\tweak thickness #3
2378 The music stream which is generated from a section of an input file,
2379 including any automatically inserted elements, may be examined,
2380 see @rextend{Displaying music expressions}. This may be helpful in
2381 determining what may be modified by a @code{\tweak} command, or
2382 in determining how to adjust the input to make a @code{\tweak}
2387 @rlearning{Tweaking methods}.
2390 @rextend{Displaying music expressions}.
2394 @cindex tweaking control points
2395 @cindex control points, tweaking
2397 The @code{\tweak} command cannot be used to modify the control
2398 points of just one of several ties in a chord, other than the first
2399 one encountered in the input file.
2401 @node set versus override
2402 @subsection @code{\set} vs. @code{\override}
2404 @c TODO -- This section is probably unnecessary now.
2407 We have seen two methods of changing properties: @code{\set} and
2408 @code{\override}. There are actually two different kinds of
2411 @code{fontSize} is a special property: it is equivalent to
2412 entering @code{\override @dots{} #'font-size} for all pertinent
2413 objects. Since this is a common change, the special
2414 property (modified with @code{\set}) was created.
2419 @node Modifying alists
2420 @subsection Modifying alists
2422 Some user-configurable properties are internally represented as
2423 @emph{alists} (association lists), which store pairs of
2424 @emph{keys} and @emph{values}. The structure of an alist is:
2427 '((@var{key1} . @var{value1})
2428 (@var{key2} . @var{value2})
2429 (@var{key3} . @var{value3})
2433 If an alist is a grob property or @code{\paper} variable, its keys
2434 can be modified individually without affecting other keys.
2436 For example, to reduce the space between adjacent staves in a
2437 staff-group, use the @code{staff-staff-spacing} property of the
2438 @code{StaffGrouper} grob. The property is an alist with four
2439 keys: @code{basic-distance}, @code{minimum-distance},
2440 @code{padding}, and @code{stretchability}. The standard settings
2441 for this property are listed in the @qq{Backend} section of the
2442 Internals Reference (see @rinternals{StaffGrouper}):
2445 '((basic-distance . 9)
2446 (minimum-distance . 7)
2448 (stretchability . 5))
2451 One way to bring the staves closer together is by reducing the
2452 value of the @code{basic-distance} key (@code{9}) to match the
2453 value of @code{minimum-distance} (@code{7}). To modify a single
2454 key individually, use a @emph{nested declaration}:
2456 @lilypond[quote,verbatim]
2457 % default space between staves
2459 \new Staff { \clef treble c''1 }
2460 \new Staff { \clef bass c1 }
2463 % reduced space between staves
2464 \new PianoStaff \with {
2465 % this is the nested declaration
2466 \override StaffGrouper.staff-staff-spacing.basic-distance = #7
2468 \new Staff { \clef treble c''1 }
2469 \new Staff { \clef bass c1 }
2473 Using a nested declaration will update the specified key (such as
2474 @code{basic-distance} in the above example) without altering any
2475 other keys already set for the same property.
2477 Now suppose we want the staves to be as close as possible without
2478 overlapping. The simplest way to do this is to set all four alist
2479 keys to zero. However, it is not necessary to enter four nested
2480 declarations, one for each key. Instead, the property can be
2481 completely re-defined with one declaration, as an alist:
2483 @lilypond[quote,verbatim]
2484 \new PianoStaff \with {
2485 \override StaffGrouper.staff-staff-spacing =
2486 #'((basic-distance . 0)
2487 (minimum-distance . 0)
2489 (stretchability . 0))
2491 \new Staff { \clef treble c''1 }
2492 \new Staff { \clef bass c1 }
2496 Note that any keys not explicitly listed in the alist definition
2497 will be reset to their @emph{default-when-unset} values. In the
2498 case of @code{staff-staff-spacing}, any unset key-values would be
2499 reset to zero (except @code{stretchability}, which takes the value
2500 of @code{basic-distance} when unset). Thus the following two
2501 declarations are equivalent:
2504 \override StaffGrouper.staff-staff-spacing =
2505 #'((basic-distance . 7))
2507 \override StaffGrouper.staff-staff-spacing =
2508 #'((basic-distance . 7)
2509 (minimum-distance . 0)
2511 (stretchability . 7))
2514 One (possibly unintended) consequence of this is the removal of
2515 any standard settings that are set in an initialization file and
2516 loaded each time an input file is compiled. In the above example,
2517 the standard settings for @code{padding} and
2518 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2519 are reset to their default-when-unset values (zero for both keys).
2520 Defining a property or variable as an alist (of any size) will
2521 always reset all unset key-values to their default-when-unset
2522 values. Unless this is the intended result, it is safer to update
2523 key-values individually with a nested declaration.
2525 @warning{Nested declarations will not work for context property
2526 alists (such as @code{beamExceptions}, @code{keySignature},
2527 @code{timeSignatureSettings}, etc.). These properties can only be
2528 modified by completely re-defining them as alists.}
2531 @node Useful concepts and properties
2532 @section Useful concepts and properties
2537 * Direction and placement::
2538 * Distances and measurements::
2539 * Staff symbol properties::
2541 * Visibility of objects::
2543 * Rotating objects::
2547 @subsection Input modes
2549 The way in which the notation contained within an input file is
2550 interpreted is determined by the current input mode.
2554 This is activated with the @code{\chordmode} command, and causes
2555 input to be interpreted with the syntax of chord notation, see
2556 @ref{Chord notation}. Chords are rendered as notes on a staff.
2558 Chord mode is also activated with the @code{\chords} command.
2559 This also creates a new @code{ChordNames} context and
2560 causes the following input to be interpreted with the syntax of
2561 chord notation and rendered as chord names in the @code{ChordNames}
2562 context, see @ref{Printing chord names}.
2566 This is activated with the @code{\drummode} command, and causes
2567 input to be interpreted with the syntax of drum notation, see
2568 @ref{Basic percussion notation}.
2570 Drum mode is also activated with the @code{\drums} command.
2571 This also creates a new @code{DrumStaff} context and causes the
2572 following input to be interpreted with the syntax of drum notation
2573 and rendered as drum symbols on a drum staff, see @ref{Basic
2574 percussion notation}.
2576 @strong{Figure mode}
2578 This is activated with the @code{\figuremode} command, and causes
2579 input to be interpreted with the syntax of figured bass, see
2580 @ref{Entering figured bass}.
2582 Figure mode is also activated with the @code{\figures} command.
2583 This also creates a new @code{FiguredBass} context and causes the
2584 following input to be interpreted with the figured bass syntax
2585 and rendered as figured bass symbols in the @code{FiguredBass}
2586 context, see @ref{Introduction to figured bass}.
2588 @strong{Fret and tab modes}
2590 There are no special input modes for entering fret and tab symbols.
2592 To create tab diagrams, enter notes or chords in note mode and
2593 render them in a @code{TabStaff} context, see
2594 @ref{Default tablatures}.
2596 To create fret diagrams above a staff, you have two choices.
2597 You can either use the @code{FretBoards} context (see
2598 @ref{Automatic fret diagrams} or you can enter them as a markup
2599 above the notes using the @code{\fret-diagram} command (see
2600 @ref{Fret diagram markups}).
2602 @strong{Lyrics mode}
2604 This is activated with the @code{\lyricmode} command, and causes
2605 input to be interpreted as lyric syllables with optional durations
2606 and associated lyric modifiers, see @ref{Vocal music}.
2608 Lyric mode is also activated with the @code{\addlyrics} command.
2609 This also creates a new @code{Lyrics} context and an implicit
2610 @code{\lyricsto} command which associates the following lyrics
2611 with the preceding music.
2613 @strong{Markup mode}
2615 This is activated with the @code{\markup} command, and causes
2616 input to be interpreted with the syntax of markup, see
2617 @ref{Text markup commands}.
2619 @c silly work-around for texinfo broken-ness
2620 @c (@strong{Note...} causes a spurious cross-reference in Info)
2623 This is the default mode or it may be activated with the
2624 @code{\notemode} command. Input is interpreted as pitches,
2625 durations, markup, etc and typeset as musical notation on a staff.
2627 It is not normally necessary to specify note mode explicitly, but
2628 it may be useful to do so in certain situations, for example if you
2629 are in lyric mode, chord mode or any other mode and want to insert
2630 something that only can be done with note mode syntax.
2632 For example, to indicate dynamic markings for the verses of a
2633 choral pieces it is necessary to enter note mode to interpret
2636 @lilypond[verbatim,relative=2,quote]
2639 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2643 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2650 @node Direction and placement
2651 @subsection Direction and placement
2653 In typesetting music the direction and placement of many items is
2654 a matter of choice. For example, the stems of notes can
2655 be directed up or down; lyrics, dynamics, and other expressive
2656 marks may be placed above or below the staff; text may be aligned
2657 left, right or center; etc. Most of these choices may be left to
2658 be determined automatically by LilyPond, but in some cases it may
2659 be desirable to force a particular direction or placement.
2662 * Articulation direction indicators::
2663 * The direction property::
2666 @node Articulation direction indicators
2667 @unnumberedsubsubsec Articulation direction indicators
2669 By default some directions are always up or always down (e.g.
2670 dynamics or fermata), while other things can alternate between
2671 up or down based on the stem direction (like slurs or accents).
2673 @c TODO Add table showing these
2675 The default action may be overridden by prefixing the articulation
2676 by a @emph{direction indicator}. Three direction indicators are
2677 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2678 and @code{-} (meaning @qq{use default direction}). The direction
2679 indicator can usually be omitted, in which case @code{-} is assumed,
2680 but a direction indicator is @strong{always} required before
2683 @item @code{\tweak} commands
2684 @item @code{\markup} commands
2685 @item @code{\tag} commands
2686 @item string markups, e.g. -"string"
2687 @item fingering instructions, e.g. @w{@code{-1}}
2688 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2691 Direction indicators affect only the next note:
2693 @lilypond[verbatim,quote,relative=2]
2700 @node The direction property
2701 @unnumberedsubsubsec The direction property
2703 The position or direction of many layout objects is controlled by the
2704 @code{direction} property.
2706 The value of the @code{direction} property may be set to @code{1},
2707 meaning @qq{up} or @qq{above}, or to @w{@code{-1}}, meaning @qq{down} or
2708 @qq{below}. The symbols @code{UP} and @code{DOWN} may be used instead
2709 of @code{1} and @w{@code{-1}} respectively. The default direction may
2710 be specified by setting @code{direction} to @code{0} or @code{CENTER}.
2711 Alternatively, in many cases predefined commands exist to specify the
2712 direction. These are of the form
2715 @code{\xxxUp}, @code{\xxxDown} or @code{\xxxNeutral}
2719 where @code{\xxxNeutral} means @qq{use the default} direction.
2720 See @rlearning{Within-staff objects}.
2722 In a few cases, arpeggio for example, the value of the @code{direction}
2723 property can specify whether the object is to be placed to the right or
2724 left of the parent. In this case @w{@code{-1}} or @code{LEFT} means
2725 @qq{to the left} and @code{1} or @code{RIGHT} means @qq{to the right}.
2726 @code{0} or @code{CENTER} means @qq{use the default} direction.
2729 These all have side-axis set to #X
2730 AmbitusAccidental - direction has no effect
2732 StanzaNumber - not tried
2733 TrillPitchAccidental - not tried
2734 TrillPitchGroup - not tried
2737 These indications affect all notes until they are canceled.
2739 @lilypond[verbatim,quote,relative=2]
2748 In polyphonic music, it is generally better to specify an explicit
2749 @code{voice} than change an object's direction. For more information.
2750 See @ref{Multiple voices}.
2754 @rlearning{Within-staff objects}.
2757 @ref{Multiple voices}.
2760 @node Distances and measurements
2761 @subsection Distances and measurements
2763 @cindex distances, absolute
2764 @cindex distances, scaled
2771 Distances in LilyPond are of two types: absolute and scaled.
2773 Absolute distances are used for specifying margins, indents, and
2774 other page layout details, and are by default specified in
2775 millimeters. Distances may be specified in other units by
2776 following the quantity by @code{\mm}, @code{\cm},
2777 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2778 an inch). Page layout distances can also be specified in scalable
2779 units (see the following paragraph) by appending
2780 @code{\staff-space} to the quantity. Page layout is described in
2781 detail in @ref{Page layout}.
2783 Scaled distances are always specified in units of the staff-space
2784 or, rarely, the half staff-space. The staff-space is the distance
2785 between two adjacent staff lines. The default value can be changed
2786 globally by setting the global staff size, or it can be overridden
2787 locally by changing the @code{staff-space} property of
2788 @code{StaffSymbol}. Scaled distances automatically scale with any
2789 change to the either the global staff size or the
2790 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2791 automatically only with changes to the global staff size.
2792 The global staff size thus enables the overall size of a rendered
2793 score to be easily varied. For the methods of setting the global
2794 staff size see @ref{Setting the staff size}.
2798 If just a section of a score needs to be rendered to a different
2799 scale, for example an ossia section or a footnote, the global staff
2800 size cannot simply be changed as this would affect the entire score.
2801 In such cases the change in size is made by overriding both the
2802 @code{staff-space} property of @code{StaffSymbol} and the size of
2803 the fonts. A Scheme function, @code{magstep}, is available to
2804 convert from a font size change to the equivalent change in
2805 @code{staff-space}. For an explanation and an example of its use,
2806 see @rlearning{Length and thickness of objects}.
2810 @rlearning{Length and thickness of objects}.
2814 @ref{Setting the staff size}.
2817 @node Staff symbol properties
2818 @subsection Staff symbol properties
2820 @cindex adjusting staff symbol
2821 @cindex drawing staff symbol
2822 @cindex staff symbol, setting of
2824 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2825 @c Need to think of uses for these properties. Eg 'line-positions
2826 @c is used in a snippet to thicken centre line.
2827 @c If retained, add @ref to here in 1.6.2 -td
2829 The vertical position of staff lines and the number of staff lines
2830 can be defined at the same time. As the following example shows,
2831 note positions are not influenced by the staff line positions.
2833 @warning{The @code{'line-positions} property overrides the
2834 @code{'line-count} property. The number of staff lines is
2835 implicitly defined by the number of elements in the list of values
2836 for @code{'line-positions}.}
2838 @lilypond[verbatim,quote,relative=1]
2840 \override StaffSymbol.line-positions = #'(7 3 0 -4 -6 -7)
2845 The width of a staff can be modified. The units are staff
2846 spaces. The spacing of objects inside the staff is not affected by
2849 @lilypond[verbatim,quote,relative=1]
2851 \override StaffSymbol.width = #23
2858 @subsection Spanners
2860 Many objects of musical notation extend over several notes or even
2861 several bars. Examples are slurs, beams, tuplet brackets, volta
2862 repeat brackets, crescendi, trills, and glissandi. Such objects
2863 are collectively called @qq{spanners}, and have special properties to control
2864 their appearance and behaviour. Some of these properties are common
2865 to all spanners; others are restricted to a sub-set of the spanners.
2867 All spanners support the @code{spanner-interface}. A few, essentially
2868 those that draw a straight line between the two objects, support in
2869 addition the @code{line-spanner-interface}.
2872 * Using the spanner-interface::
2873 * Using the line-spanner-interface::
2876 @node Using the spanner-interface
2877 @unnumberedsubsubsec Using the @code{spanner-interface}
2879 This interface provides two properties that apply to several spanners.
2881 @subsubsubheading The @code{minimum-length} property
2883 The minimum length of the spanner is specified by the
2884 @code{minimum-length} property. Increasing this usually has the
2885 necessary effect of increasing the spacing of the notes between the
2886 two end points. However, this override has no effect on
2887 many spanners, as their length is determined by other considerations.
2888 A few examples where it is effective are shown below.
2898 Works as long as callback is made:
2902 Works not at all for:
2911 @lilypond[verbatim,quote,relative=2]
2914 % increase the length of the tie
2915 -\tweak minimum-length #5
2919 @lilypond[verbatim,quote,relative=2]
2921 \compressFullBarRests
2923 % increase the length of the rest bar
2924 \once \override MultiMeasureRest.minimum-length = #20
2929 @lilypond[verbatim,quote,relative=2]
2931 % increase the length of the hairpin
2932 \override Hairpin.minimum-length = #20
2936 This override can also be used to increase the length of slurs and
2939 @lilypond[verbatim,quote,relative=2]
2942 -\tweak minimum-length #5
2947 -\tweak minimum-length #5
2951 For some layout objects, the @code{minimum-length} property becomes
2952 effective only if the @code{set-spacing-rods} procedure is called
2953 explicitly. To do this, the @code{springs-and-rods} property should
2954 be set to @code{ly:spanner::set-spacing-rods}. For example,
2955 the minimum length of a glissando has no effect unless the
2956 @code{springs-and-rods} property is set:
2958 @lilypond[verbatim,quote,relative=1]
2962 % not effective alone
2963 \once \override Glissando.minimum-length = #20
2966 % effective only when both overrides are present
2967 \once \override Glissando.minimum-length = #20
2968 \once \override Glissando.springs-and-rods = #ly:spanner::set-spacing-rods
2972 The same is true of the @code{Beam} object:
2974 @lilypond[verbatim,quote,relative=1]
2975 % not effective alone
2976 \once \override Beam.minimum-length = #20
2979 % effective only when both overrides are present
2980 \once \override Beam.minimum-length = #20
2981 \once \override Beam.springs-and-rods = #ly:spanner::set-spacing-rods
2985 @subsubsubheading The @code{to-barline} property
2987 The second useful property of the @code{spanner-interface} is
2988 @code{to-barline}. By default this is true, causing hairpins and
2989 other spanners which are terminated on the first note of a measure to
2990 end instead on the immediately preceding bar line. If set to false,
2991 the spanner will extend beyond the bar line and end on the note
2994 @lilypond[verbatim,quote,relative=2]
2995 a \< a a a a \! a a a \break
2996 \override Hairpin.to-barline = ##f
2997 a \< a a a a \! a a a
3000 This property is not effective for all spanners. For example,
3001 setting it to @code{#t} has no effect on slurs or phrasing slurs
3002 or on other spanners for which terminating on the bar line would
3005 @node Using the line-spanner-interface
3006 @unnumberedsubsubsec Using the @code{line-spanner-interface}
3008 Objects which support the @code{line-spanner-interface} include
3011 @item @code{DynamicTextSpanner}
3012 @item @code{Glissando}
3013 @item @code{TextSpanner}
3014 @item @code{TrillSpanner}
3015 @item @code{VoiceFollower}
3018 The routine responsible for drawing the stencils for these spanners is
3019 @code{ly:line-interface::print}. This routine determines the
3020 exact location of the two end points and draws a line
3021 between them, in the style requested. The locations of the two
3022 end points of the spanner are computed on-the-fly, but it is
3023 possible to override their Y-coordinates. The
3024 properties which need to be specified are nested
3025 two levels down within the property hierarchy, but the syntax of
3026 the @code{\override} command is quite simple:
3028 @lilypond[relative=2,quote,verbatim]
3030 \once \override Glissando.bound-details.left.Y = #3
3031 \once \override Glissando.bound-details.right.Y = #-2
3035 The units for the @code{Y} property are @code{staff-space}s,
3036 with the center line of the staff being the zero point.
3037 For the glissando, this is the value for @code{Y} at the
3038 X-coordinate corresponding to the center point of each note head,
3039 if the line is imagined to be extended to there.
3041 If @code{Y} is not set, the value is computed from the vertical
3042 position of the corresponding attachment point of the spanner.
3044 In case of a line break, the values for the end points are
3045 specified by the @code{left-broken} and @code{right-broken}
3046 sub-lists of @code{bound-details}. For example:
3048 @lilypond[relative=2,ragged-right,verbatim,quote]
3049 \override Glissando.breakable = ##t
3050 \override Glissando.bound-details.right-broken.Y = #-3
3051 c1 \glissando \break
3056 A number of further properties of the @code{left} and
3057 @code{right} sub-lists of the @code{bound-details} property
3058 may be modified in the same way as @code{Y}:
3062 This sets the Y-coordinate of the end point, in @code{staff-space}s
3063 offset from the staff center line. By default, it is the center of
3064 the bound object, so a glissando points to the vertical center of
3067 For horizontal spanners, such as text spanners and trill spanners,
3068 it is hardcoded to 0.
3071 This determines where the line starts and ends in the X-direction,
3072 relative to the bound object. So, a value of @w{@code{-1}} (or
3073 @code{LEFT}) makes the line start/end at the left side of the note
3074 head it is attached to.
3077 This is the absolute X-coordinate of the end point. It is usually
3078 computed on the fly, and overriding it has little useful effect.
3081 Line spanners may have symbols at the beginning or end, which is
3082 contained in this sub-property. This is for internal use; it is
3083 recommended that @code{text} be used instead.
3086 This is a markup that is evaluated to yield the stencil. It is used
3087 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
3089 @lilypond[quote,ragged-right,relative=2,verbatim]
3090 \override TextSpanner.bound-details.left.text
3091 = \markup { \small \bold Slower }
3092 c2\startTextSpan b c a\stopTextSpan
3095 @item stencil-align-dir-y
3096 @item stencil-offset
3097 Without setting one of these, the stencil is simply put at the
3098 end-point, centered on the line, as defined by the @code{X} and
3099 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
3100 or @code{stencil-offset} will move the symbol at the edge vertically
3101 relative to the end point of the line:
3103 @lilypond[relative=1,quote,verbatim]
3104 \override TextSpanner.bound-details.left.stencil-align-dir-y = #-2
3105 \override TextSpanner.bound-details.right.stencil-align-dir-y = #UP
3107 \override TextSpanner.bound-details.left.text = #"ggg"
3108 \override TextSpanner.bound-details.right.text = #"hhh"
3109 c4^\startTextSpan c c c \stopTextSpan
3112 Note that negative values move the text @emph{up}, contrary to the
3113 effect that might be expected, as a value of @w{@code{-1}} or
3114 @code{DOWN} means align the @emph{bottom} edge of the text with
3115 the spanner line. A value of @code{1} or @code{UP} aligns
3116 the top edge of the text with the spanner line.
3119 Setting this sub-property to @code{#t} produces an arrowhead at the
3123 This sub-property controls the space between the specified
3124 end point of the line and the actual end. Without padding, a
3125 glissando would start and end in the center of each note head.
3129 The music function @code{\endSpanners} terminates the spanner
3130 which starts on the immediately following note prematurely. It
3131 is terminated after exactly one note, or at the following bar line
3132 if @code{to-barline} is true and a bar line occurs before the next
3135 @lilypond[verbatim,quote,ragged-right,relative=2]
3137 c2 \startTextSpan c2 c2
3142 When using @code{\endSpanners} it is not necessary to close
3143 \startTextSpan with \stopTextSpan, nor is it necessary to close
3144 hairpins with @code{\!}.
3147 Internals Reference:
3148 @rinternals{TextSpanner},
3149 @rinternals{Glissando},
3150 @rinternals{VoiceFollower},
3151 @rinternals{TrillSpanner},
3152 @rinternals{line-spanner-interface}.
3155 @node Visibility of objects
3156 @subsection Visibility of objects
3158 @cindex objects, visibility of
3159 @cindex grobs, visibility of
3160 @cindex visibility of objects
3162 There are four main ways in which the visibility of layout objects
3163 can be controlled: their stencil can be removed, they can be made
3164 transparent, they can be colored white, or their
3165 @code{break-visibility} property can be overridden. The first
3166 three apply to all layout objects; the last to just a few -- the
3167 @emph{breakable} objects. The Learning Manual introduces these
3168 four techniques, see @rlearning{Visibility and color of objects}.
3170 There are also a few other techniques which are specific to
3171 certain layout objects. These are covered under Special
3175 * Removing the stencil::
3176 * Making objects transparent::
3177 * Painting objects white::
3178 * Using break-visibility::
3179 * Special considerations::
3183 @node Removing the stencil
3184 @unnumberedsubsubsec Removing the stencil
3186 @cindex stencil, removing
3189 Every layout object has a stencil property. By default this is set
3190 to the specific function which draws that object. If this property
3191 is overridden to @code{#f} no function will be called and the object
3192 will not be drawn. The default action can be recovered with
3195 @lilypond[quote,verbatim,relative=1]
3197 \override Score.BarLine.stencil = ##f
3199 \revert Score.BarLine.stencil
3203 This rather common operation has a shortcut @code{\omit}:
3205 @lilypond[quote,verbatim,relative=1]
3209 \undo \omit Score.BarLine
3213 @node Making objects transparent
3214 @unnumberedsubsubsec Making objects transparent
3216 @cindex transparent, making objects
3219 Every layout object has a transparent property which by default is
3220 set to @code{#f}. If set to @code{#t} the object still occupies
3221 space but is made invisible.
3223 @lilypond[quote,verbatim,relative=2]
3225 \once \override NoteHead.transparent = ##t
3229 This rather common operation has a shortcut @code{\hide}:
3231 @lilypond[quote,verbatim,relative=2]
3233 \once \hide NoteHead
3237 @node Painting objects white
3238 @unnumberedsubsubsec Painting objects white
3240 @cindex objects, coloring
3241 @cindex coloring objects
3243 @cindex printing order
3244 @cindex overwriting objects
3245 @cindex objects, overwriting
3246 @cindex grobs, overwriting
3248 Every layout object has a color property which by default is set
3249 to @code{black}. If this is overridden to @code{white} the object
3250 will be indistinguishable from the white background. However,
3251 if the object crosses other objects the color of the crossing
3252 points will be determined by the order in which they are drawn,
3253 and this may leave a ghostly image of the white object, as shown
3256 @lilypond[quote,verbatim,relative=2]
3257 \override Staff.Clef.color = #white
3261 This may be avoided by changing the order of printing the objects.
3262 All layout objects have a @code{layer} property which should be set
3263 to an integer. Objects with the lowest value of @code{layer} are
3264 drawn first, then objects with progressively higher values are drawn,
3265 so objects with higher values overwrite objects with lower values.
3266 By default most objects are assigned a @code{layer} value of
3267 @code{1}, although a few objects, including @code{StaffSymbol} and
3268 @code{BarLine}, are assigned a value of @code{0}. The order of
3269 printing objects with the same value of @code{layer} is indeterminate.
3271 In the example above the white clef, with a default @code{layer}
3272 value of @code{1}, is drawn after the staff lines (default
3273 @code{layer} value @code{0}), so overwriting them. To change this,
3274 the @code{Clef} object must be given in a lower value of
3275 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
3277 @lilypond[quote,verbatim,relative=2]
3278 \override Staff.Clef.color = #white
3279 \override Staff.Clef.layer = #-1
3283 @node Using break-visibility
3284 @unnumberedsubsubsec Using break-visibility
3286 @c TODO Add making other objects breakable
3288 @cindex break-visibility
3290 Most layout objects are printed only once, but some like
3291 bar lines, clefs, time signatures and key signatures, may need
3292 to be printed twice when a line break occurs -- once at the end
3293 of the line and again at the start of the next line. Such
3294 objects are called @emph{breakable}, and have a property, the
3295 @code{break-visibility} property to control their visibility
3296 at the three positions in which they may appear -- at the
3297 start of a line, within a line if they are changed, and at the
3298 end of a line if a change takes place there.
3300 For example, the time signature
3301 by default will be printed at the start of the first line, but
3302 nowhere else unless it changes, when it will be printed at the
3303 point at which the change occurs. If this change occurs at the
3304 end of a line the new time signature will be printed at the start
3305 of the next line and a cautionary time signature will be printed
3306 at the end of the previous line as well.
3308 This behaviour is controlled by the @code{break-visibility}
3309 property, which is explained in
3310 @c Leave this ref on a newline - formats incorrectly otherwise -td
3311 @rlearning{Visibility and color of objects}. This property takes
3312 a vector of three booleans which, in order, determine whether the
3313 object is printed at the end of, within the body of, or at the
3314 beginning of a line. Or to be more precise, before a line break,
3315 where there is no line break, or after a line break.
3317 Alternatively, these eight combinations may be specified
3318 by pre-defined functions, defined in @file{scm/output-lib.scm},
3319 where the last three columns indicate whether the layout objects
3320 will be visible in the positions shown at the head of the columns:
3322 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {Before} {At no} {After}
3323 @headitem Function @tab Vector @tab Before @tab At no @tab After
3324 @headitem form @tab form @tab break @tab break @tab break
3326 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
3327 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
3328 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
3329 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
3330 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
3331 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
3332 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
3333 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
3336 The default settings of @code{break-visibility} depend on the
3337 layout object. The following table shows all the layout objects
3338 of interest which are affected by @code{break-visibility} and the
3339 default setting of this property:
3341 @multitable @columnfractions .3 .3 .4
3343 @headitem Layout object @tab Usual context @tab Default setting
3345 @c omit Ambitus as it appears not to be affected by break-visibility -td
3346 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
3347 @item @code{BarLine} @tab @code{Score} @tab calculated
3348 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
3349 @c omit the following item until it can be explained -td
3350 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
3351 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3352 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
3353 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
3354 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3355 @item @code{KeyCancellation} @tab @code{Staff} @tab @code{begin-of-line-invisible}
3356 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
3357 @c omit LeftEdge until it can be explained -td
3358 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
3359 @item @code{ClefModifier} @tab @code{Staff} @tab @code{begin-of-line-visible}
3360 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
3361 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
3365 The example below shows the use of the vector form to control the
3366 visibility of bar lines:
3368 @lilypond[quote,verbatim,relative=1,ragged-right]
3371 % Remove bar line at the end of the current line
3372 \once \override Score.BarLine.break-visibility = ##(#f #t #t)
3378 Although all three components of the vector used to override
3379 @code{break-visibility} must be present, not all of them are
3380 effective with every layout object, and some combinations may
3381 even give errors. The following limitations apply:
3384 @item Bar lines cannot be printed at start of line.
3385 @item A bar number cannot be printed at the start of the first
3386 line unless it is set to be different from 1.
3387 @item Clef -- see below
3388 @item Double percent repeats are either all printed or all
3389 suppressed. Use begin-of line-invisible to print and
3390 all-invisible to suppress.
3391 @item Key signature -- see below
3392 @item ClefModifier -- see below
3395 @node Special considerations
3396 @unnumberedsubsubsec Special considerations
3398 @subsubsubheading Visibility following explicit changes
3400 @cindex key signature, visibility following explicit change
3401 @cindex explicitKeySignatureVisibility
3402 @cindex clef, visibility following explicit change
3403 @cindex explicitClefVisibility
3405 The @code{break-visibility} property controls the visibility of
3406 key signatures and changes of clef only at the start of lines,
3407 i.e. after a break. It has no effect on the visibility of the
3408 key signature or clef following an explicit key change or an
3409 explicit clef change within or at the end of a line. In the
3410 following example the key signature following the explicit change
3411 to B-flat major is still visible, even though @code{all-invisible}
3414 @lilypond[quote,verbatim,relative=1,ragged-right]
3417 % Try to remove all key signatures
3418 \override Staff.KeySignature.break-visibility = #all-invisible
3426 The visibility of such explicit key signature and clef changes is
3427 controlled by the @code{explicitKeySignatureVisibility} and
3428 @code{explicitClefVisibility} properties. These are the equivalent
3429 of the @code{break-visibility} property and both take a vector of
3430 three booleans or the predefined functions listed above, exactly like
3431 @code{break-visibility}. Both are properties of the Staff context,
3432 not the layout objects themselves, and so they are set using the
3433 @code{\set} command. Both are set by default to @code{all-visible}.
3434 These properties control only the visibility of key signatures and
3435 clefs resulting from explicit changes and do not affect key
3436 signatures and clefs at the beginning of lines;
3437 @code{break-visibility} must still be overridden in the appropriate
3438 object to remove these.
3440 @lilypond[quote,verbatim,relative=1,ragged-right]
3443 \set Staff.explicitKeySignatureVisibility = #all-invisible
3444 \override Staff.KeySignature.break-visibility = #all-invisible
3451 @subsubsubheading Visibility of cancelling accidentals
3453 To remove the cancelling accidentals printed at an explicit key
3454 change, set the Staff context property @code{printKeyCancellation}
3457 @lilypond[quote,verbatim,relative=1,ragged-right]
3460 \set Staff.explicitKeySignatureVisibility = #all-invisible
3461 \set Staff.printKeyCancellation = ##f
3462 \override Staff.KeySignature.break-visibility = #all-invisible
3469 With these overrides only the accidentals before the notes remain
3470 to indicate the change of key.
3472 Note that when changing the key to C@tie{}major or A@tie{}minor
3473 the cancelling accidentals would be the @emph{only} indication of
3474 the key change. In this case setting @code{printKeyCancellation} to
3475 @code{#f} has no effect:
3477 @lilypond[quote,verbatim,relative=1,ragged-right]
3480 \set Staff.explicitKeySignatureVisibility = #all-invisible
3481 \set Staff.printKeyCancellation = ##f
3488 To suppress the cancelling accidentals even when the key is
3489 changed to C@tie{}major or A@tie{}minor, override
3490 the visibility of the @code{KeyCancellation} grob instead:
3492 @lilypond[quote,verbatim,relative=1,ragged-right]
3495 \set Staff.explicitKeySignatureVisibility = #all-invisible
3496 \override Staff.KeyCancellation.break-visibility = #all-invisible
3503 @c TODO Add visibility of cautionary accidentals before notes
3505 @subsubsubheading Automatic bars
3507 @cindex automaticBars
3508 @cindex bar lines, suppressing
3510 As a special case, the printing of bar lines can also be turned off
3511 by setting the @code{automaticBars} property in the Score context.
3512 If set to @code{#f}, bar lines will not be printed automatically;
3513 they must be explicitly created with a @code{\bar} command. Unlike
3514 the @code{\cadenzaOn} predefined command, measures are still counted.
3515 Bar generation will resume according to that count if this property
3516 is later set to @code{#t}. When set to @code{#f}, line breaks can
3517 occur only at explicit @code{\bar} commands.
3521 @subsubsubheading Transposed clefs
3523 @cindex transposed clefs, visibility of
3524 @cindex visibility of transposed clefs
3525 @cindex clefs, visibility of transposition
3527 The small transposition symbol on transposed clefs is produced by the
3528 @code{ClefModifier} layout object. Its visibility is automatically
3529 inherited from the @code{Clef} object, so it is not necessary to apply
3530 any required @code{break-visibility} overrides to the @code{ClefModifier}
3531 layout objects to suppress transposition symbols for invisible clefs.
3533 For explicit clef changes, the @code{explicitClefVisibility}
3534 property controls both the clef symbol and any transposition symbol
3539 @rlearning{Visibility and color of objects}.
3543 @subsection Line styles
3545 Some performance indications, e.g., @i{rallentando} and
3546 @i{accelerando} and @i{trills} are written as text and are
3547 extended over many measures with lines, sometimes dotted or wavy.
3549 These all use the same routines as the glissando for drawing the
3550 texts and the lines, and tuning their behavior is therefore also
3551 done in the same way. It is done with a spanner, and the routine
3552 responsible for drawing the spanners is
3553 @code{ly:line-interface::print}. This routine determines the
3554 exact location of the two @i{span points} and draws a line
3555 between them, in the style requested.
3557 Here is an example showing the different line styles available,
3558 and how to tune them.
3560 @lilypond[relative=2,ragged-right,verbatim,quote]
3562 \once \override Glissando.style = #'dashed-line
3564 \override Glissando.style = #'dotted-line
3566 \override Glissando.style = #'zigzag
3568 \override Glissando.style = #'trill
3572 The locations of the end-points of the spanner are computed
3573 on-the-fly for every graphic object, but it is possible to
3577 @lilypond[relative=2,ragged-right,verbatim,quote]
3579 \once \override Glissando.bound-details.right.Y = #-2
3583 The value for @code{Y} is set to @w{@code{-2}} for the right end
3584 point. The left side may be similarly adjusted by specifying
3585 @code{left} instead of @code{right}.
3587 If @code{Y} is not set, the value is computed from the vertical
3588 position of the left and right attachment points of the spanner.
3590 Other adjustments of spanners are possible, for details, see
3593 @node Rotating objects
3594 @subsection Rotating objects
3596 Both layout objects and elements of markup text can be rotated by
3597 any angle about any point, but the method of doing so differs.
3600 * Rotating layout objects::
3604 @node Rotating layout objects
3605 @unnumberedsubsubsec Rotating layout objects
3607 @cindex rotating objects
3608 @cindex objects, rotating
3610 All layout objects which support the @code{grob-interface} can be
3611 rotated by setting their @code{rotation} property. This takes a
3612 list of three items: the angle of rotation counter-clockwise,
3613 and the x and y coordinates of the point relative to the object's
3614 reference point about which the rotation is to be performed. The
3615 angle of rotation is specified in degrees and the coordinates in
3618 The angle of rotation and the coordinates of the rotation point must
3619 be determined by trial and error.
3621 @cindex hairpins, angled
3622 @cindex angled hairpins
3624 There are only a few situations where the rotation of layout
3625 objects is useful; the following example shows one situation where
3628 @lilypond[quote,verbatim,relative=1]
3630 \override Hairpin.rotation = #'(20 -1 0)
3634 @node Rotating markup
3635 @unnumberedsubsubsec Rotating markup
3637 All markup text can be rotated to lie at any angle by prefixing it
3638 with the @code{\rotate} command. The command takes two arguments:
3639 the angle of rotation in degrees counter-clockwise and the text to
3640 be rotated. The extents of the text are not rotated: they take
3641 their values from the extremes of the x and y coordinates of the
3642 rotated text. In the following example the
3643 @code{outside-staff-priority} property for text is set to @code{#f}
3644 to disable the automatic collision avoidance, which would push some
3645 of the text too high.
3647 @lilypond[quote,verbatim,relative=1]
3648 \override TextScript.outside-staff-priority = ##f
3649 g4^\markup { \rotate #30 "a G" }
3650 b^\markup { \rotate #30 "a B" }
3651 des^\markup { \rotate #30 "a D-Flat" }
3652 fis^\markup { \rotate #30 "an F-Sharp" }
3655 @node Advanced tweaks
3656 @section Advanced tweaks
3658 This section discusses various approaches to fine tuning the
3659 appearance of the printed score.
3662 * Aligning objects::
3663 * Vertical grouping of grobs::
3664 * Modifying stencils::
3665 * Modifying shapes::
3666 * Unpure-pure containers::
3671 @rlearning{Tweaking output},
3672 @rlearning{Other sources of information}.
3675 @ref{Explaining the Internals Reference},
3676 @ref{Modifying properties}.
3679 @rextend{Interfaces for programmers}.
3682 @file{scm/define-grobs.scm}.
3685 @rlsr{Tweaks and overrides}.
3687 Internals Reference:
3688 @rinternals{All layout objects}.
3691 @node Aligning objects
3692 @subsection Aligning objects
3694 Graphical objects which support the @code{self-alignment-interface}
3695 and/or the @code{side-position-interface} can be aligned to a previously
3696 placed object in a variety of ways. For a list of these objects, see
3697 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3699 All graphical objects have a reference point, a horizontal extent and a
3700 vertical extent. The horizontal extent is a pair of numbers
3701 giving the displacements from the reference point of the left and
3702 right edges, displacements to the left being negative. The vertical
3703 extent is a pair of numbers giving the displacement from the reference
3704 point to the bottom and top edges, displacements down being negative.
3706 An object's position on a staff is given by the values of the
3707 @code{X-offset} and @code{Y-offset} properties. The value of
3708 @code{X-offset} gives the displacement from the X coordinate of
3709 the reference point of the parent object, and the value of
3710 @code{Y-offset} gives the displacement from the center line of the
3711 staff. The values of @code{X-offset} and @code{Y-offset} may
3712 be set directly or may be set to be calculated by procedures in order
3713 to achieve alignment with the parent object.
3715 @warning{Many objects have special positioning considerations which
3716 cause any setting of @code{X-offset} or @code{Y-offset} to be
3717 ignored or modified, even though the object supports the
3718 @code{self-alignment-interface}. Overriding the @code{X-offset}
3719 or @code{Y-offset} properties to a fixed value causes the respective
3720 @code{self-alignment} property to be disregarded.}
3722 For example, an accidental can be repositioned vertically by setting
3723 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3725 Rehearsal marks may be aligned with breakable objects such as bar
3726 lines, clef symbols, time signature symbols and key signatures. There
3727 are special properties to be found in the @code{break-aligned-interface}
3728 for positioning rehearsal marks on such objects.
3732 @ref{Using the break-alignable-interface}.
3735 @rextend{Callback functions}.
3738 * Setting X-offset and Y-offset directly::
3739 * Using the side-position-interface::
3740 * Using the self-alignment-interface::
3741 * Using the break-alignable-interface::
3744 @node Setting X-offset and Y-offset directly
3745 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3747 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3748 properties of many objects. The following example shows three
3749 notes with the default fingering position and the positions with @code{X-offset}
3750 and @code{Y-offset} modified.
3752 @lilypond[verbatim,quote,relative=2]
3759 -\tweak X-offset #-1
3766 @node Using the side-position-interface
3767 @unnumberedsubsubsec Using the @code{side-position-interface}
3769 An object which supports the @code{side-position-interface} can be
3770 placed next to its parent object so that
3771 the specified edges of the two objects touch. The object may be
3772 placed above, below, to the right or to the left of the parent.
3773 The parent cannot be specified; it is determined by the order of
3774 elements in the input stream. Most objects have the associated
3775 note head as their parent.
3777 The values of the @code{side-axis} and @code{direction} properties
3778 determine where the object is to be placed, as follows:
3780 @c TODO add an example of each to the table
3782 @multitable @columnfractions .3 .3 .3
3783 @headitem @code{side-axis} @tab @code{direction} @tab
3784 @headitem property @tab property @tab Placement
3786 @item @code{0} @tab @code{-1} @tab left
3787 @item @code{0} @tab @code{1} @tab right
3788 @item @code{1} @tab @code{-1} @tab below
3789 @item @code{1} @tab @code{1} @tab above
3793 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3794 the procedure @code{ly:side-position-interface::x-aligned-side}.
3795 This procedure will return the correct value of @code{X-offset} to
3796 place the object to the left or right side of the parent according
3797 to value of @code{direction}.
3799 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3800 the procedure @code{ly:side-position-interface::y-aligned-side}.
3801 This procedure will return the correct value of @code{Y-offset} to
3802 place the object to the top or bottom of the parent according
3803 to value of @code{direction}.
3805 @c TODO Add examples
3807 @node Using the self-alignment-interface
3808 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3810 @subsubsubheading Self-aligning objects horizontally
3812 The horizontal alignment of an object which supports the
3813 @code{self-alignment-interface} is controlled by the value of
3814 the @code{self-alignment-X} property, provided the object's
3815 @code{X-offset} property is set to
3816 @code{ly:self-alignment-interface::x-aligned-on-self}.
3817 @code{self-alignment-X} may be given any
3818 real value, in units of half the total X extent of the
3819 object. Negative values move the object to the right, positive
3820 to the left. A value of @code{0} centers the object on the
3821 reference point of its parent, a value of @w{@code{-1}} aligns the
3822 left edge of the object on the reference point of its parent,
3823 and a value of @code{1} aligns the right edge of the object on the
3824 reference point of its parent. The symbols @code{LEFT},
3825 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3826 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3828 Normally the @code{\override} command would be used to modify the
3829 value of @code{self-alignment-X}, but the @code{\tweak} command
3830 can be used to separately align several annotations on a single
3833 @lilypond[quote,verbatim,relative=1]
3835 -\tweak self-alignment-X #-1
3837 -\tweak self-alignment-X #0
3839 -\tweak self-alignment-X #RIGHT
3841 -\tweak self-alignment-X #-2.5
3842 ^"aligned further to the right"
3845 @subsubsubheading Self-aligning objects vertically
3847 Objects may be aligned vertically in an analogous way to aligning
3848 them horizontally if the @code{Y-offset} property is set to
3849 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3850 other mechanisms are often involved in vertical alignment: the
3851 value of @code{Y-offset} is just one variable taken into account.
3852 This may make adjusting the value of some objects tricky.
3853 The units are just half the vertical extent of the object, which
3854 is usually quite small, so quite large numbers may be required.
3855 A value of @w{@code{-1}} aligns the lower edge of the object with
3856 the reference point of the parent object, a value of @code{0}
3857 aligns the center of the object with the reference point of the
3858 parent, and a value of @code{1} aligns the top edge of the object
3859 with the reference point of the parent. The symbols @code{DOWN},
3860 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3861 @code{0}, and @code{1}, respectively.
3863 @subsubsubheading Self-aligning objects in both directions
3865 By setting both @code{X-offset} and @code{Y-offset}, an object may
3866 be aligned in both directions simultaneously.
3868 The following example shows how to adjust a fingering mark so
3869 that it nestles close to the note head.
3871 @lilypond[quote,verbatim,relative=2]
3873 -\tweak self-alignment-X #0.5 % move horizontally left
3874 -\tweak Y-offset #ly:self-alignment-interface::y-aligned-on-self
3875 -\tweak self-alignment-Y #-1 % move vertically up
3880 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3882 @c Cannot document as they do not seem to operate consistently on all objects -td
3883 @c TODO investigate further
3885 The @code{aligned-on-parent} procedures are used in the same way
3886 as the @code{aligned-on-self} procedures, they difference being
3887 that they permit an object to be aligned with the @emph{edges} of
3888 the parent rather than the parent's reference point. The following
3889 example shows the difference:
3893 @lilypond[verbatim,quote]
3899 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3901 @c Cannot document as they do not seem to operate consistently on all objects -td
3902 @c TODO investigate further
3906 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3908 @node Using the break-alignable-interface
3909 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3911 @cindex align to objects
3912 @cindex break-align-symbols
3914 Rehearsal marks and bar numbers may be aligned with notation
3915 objects other than bar lines. These objects include @code{ambitus},
3916 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3917 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3918 @code{time-signature}.
3920 Each type of object has its own default reference point, to which
3921 rehearsal marks are aligned:
3923 @lilypond[verbatim,quote,relative=1]
3924 % The rehearsal mark will be aligned to the right edge of the Clef
3925 \override Score.RehearsalMark.break-align-symbols = #'(clef)
3930 % The rehearsal mark will be aligned to the left edge of the Time Signature
3931 \override Score.RehearsalMark.break-align-symbols = #'(time-signature)
3937 % The rehearsal mark will be centered above the Breath Mark
3938 \override Score.RehearsalMark.break-align-symbols = #'(breathing-sign)
3947 A list of possible target alignment objects may be specified. If
3948 some of the objects are invisible at that point due to the setting
3949 of @code{break-visibility} or the explicit visibility settings for
3950 keys and clefs, the rehearsal mark or bar number is aligned to the
3951 first object in the list which is visible. If no objects in the
3952 list are visible the object is aligned to the bar line. If the bar
3953 line is invisible the object is aligned to the place where the bar
3956 @lilypond[verbatim,quote,relative=1]
3957 % The rehearsal mark will be aligned to the right edge of the Key Signature
3958 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3963 % The rehearsal mark will be aligned to the right edge of the Clef
3964 \set Staff.explicitKeySignatureVisibility = #all-invisible
3965 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3970 % The rehearsal mark will be centered above the Bar Line
3971 \set Staff.explicitKeySignatureVisibility = #all-invisible
3972 \set Staff.explicitClefVisibility = #all-invisible
3973 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
3980 The alignment of the rehearsal mark relative to the notation object
3981 can be changed, as shown in the following example. In a score with
3982 multiple staves, this setting should be done for all the staves.
3984 @lilypond[verbatim,quote,relative=1]
3985 % The RehearsalMark will be aligned with the right edge of the Key Signature
3986 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
3992 % The RehearsalMark will be centered above the Key Signature
3993 \once \override Score.KeySignature.break-align-anchor-alignment = #CENTER
3997 % The RehearsalMark will be aligned with the left edge of the Key Signature
3998 \once \override Score.KeySignature.break-align-anchor-alignment = #LEFT
4004 The rehearsal mark can also be offset to the right or left of the left
4005 edge by an arbitrary amount. The units are staff-spaces:
4007 @lilypond[verbatim,quote,relative=1]
4008 % The RehearsalMark will be aligned with the left edge of the Key Signature
4009 % and then shifted right by 3.5 staff-spaces
4010 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
4011 \once \override Score.KeySignature.break-align-anchor = #3.5
4015 % The RehearsalMark will be aligned with the left edge of the Key Signature
4016 % and then shifted left by 2 staff-spaces
4017 \once \override Score.KeySignature.break-align-anchor = #-2
4024 @node Vertical grouping of grobs
4025 @subsection Vertical grouping of grobs
4027 @c TODO Expand this section
4029 The VerticalAlignment and VerticalAxisGroup grobs work together.
4030 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
4031 etc. VerticalAlignment then vertically aligns the different grobs
4032 grouped together by VerticalAxisGroup. There is usually only one
4033 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
4037 @node Modifying stencils
4038 @subsection Modifying stencils
4040 All layout objects have a @code{stencil} property which is part of
4041 the @code{grob-interface}. By default, this property is usually
4042 set to a function specific to the object that is tailor-made to
4043 render the symbol which represents it in the output. For example,
4044 the standard setting for the @code{stencil} property of the
4045 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
4047 The standard symbol for any object can be replaced by modifying the
4048 @code{stencil} property to reference a different, specially-written,
4049 procedure. This requires a high level of knowledge of the internal
4050 workings of LilyPond, but there is an easier way which can often
4051 produce adequate results.
4053 This is to set the @code{stencil} property to the procedure which
4054 prints text -- @code{ly:text-interface::print} -- and to add a
4055 @code{text} property to the object which is set to contain the
4056 markup text which produces the required symbol. Due to the
4057 flexibility of markup, much can be achieved -- see in particular
4058 @ref{Graphic notation inside markup}.
4060 The following example demonstrates this by changing the note head
4061 symbol to a cross within a circle.
4063 @lilypond[verbatim,quote]
4065 \once \override NoteHead.stencil = #ly:text-interface::print
4066 \once \override NoteHead.text = \markup {
4068 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
4069 \musicglyph #"noteheads.s2cross"
4077 Any of the glyphs in the feta Font can be supplied to the
4078 @code{\musicglyph} markup command -- see @ref{The Feta font}.
4080 @c TODO Add inserting eps files or ref to later
4082 @c TODO Add inserting Postscript or ref to later
4086 @ref{Graphic notation inside markup},
4087 @ref{Formatting text},
4088 @ref{Text markup commands},
4089 @ref{The Feta font}.
4092 @node Modifying shapes
4093 @subsection Modifying shapes
4096 * Modifying ties and slurs::
4099 @node Modifying ties and slurs
4100 @unnumberedsubsubsec Modifying ties and slurs
4102 @cindex slurs, modifying
4103 @cindex ties, modifying
4104 @cindex Bézier curves, control points
4105 @cindex control points, Bézier curves
4107 @code{Tie}s, @code{Slur}s, @code{PhrasingSlur}s,
4108 @code{LaissezVibrerTie}s and @code{RepeatTie}s are all drawn as
4109 third-order Bézier curves. If the shape of the tie or slur which
4110 is calculated automatically is not optimum, the shape may be
4111 modified manually in two ways:
4115 by specifying the displacements to be made to the control points
4116 of the automatically calculated Bézier curve, or
4119 by explicitly specifying the positions of the four control points
4120 required to define the wanted curve.
4123 Both methods are explained below. The first method is more suitable
4124 if only slight adjustments to the curve are required; the second may
4125 be better for creating curves which are related to just a single
4128 @subsubsubheading Cubic Bézier curves
4130 Third-order or cubic Bézier curves are defined by four control
4131 points. The first and fourth control points are precisely the
4132 starting and ending points of the curve. The intermediate two
4133 control points define the shape. Animations showing how the curve
4134 is drawn can be found on the web, but the following description
4135 may be helpful. The curve starts from the first control point
4136 heading directly towards the second, gradually bending over to
4137 head towards the third and continuing to bend over to head towards
4138 the fourth, arriving there travelling directly from the third
4139 control point. The curve is entirely contained in the
4140 quadrilateral defined by the four control points. Translations,
4141 rotations and scaling of the control points all result in exactly
4142 the same operations on the curve.
4144 @subsubsubheading Specifying displacements from current control points
4146 @cindex shaping slurs and ties
4149 In this example the automatic placement of the tie is not optimum,
4150 and @code{\tieDown} would not help.
4152 @lilypond[verbatim,quote,relative=1]
4156 { r4 <g c,> <g c,> <g c,> }
4160 Adjusting the control points of the tie with @code{\shape} allows
4161 the collisions to be avoided.
4163 The syntax of @code{\shape} is
4166 [-]@code{\shape} @var{displacements} @var{item}
4169 This will reposition the control-points of @var{item} by the amounts
4170 given by @var{displacements}. The @var{displacements} argument is a
4171 list of number pairs or a list of such lists. Each element of a pair
4172 represents the displacement of one of the coordinates of a
4173 control-point. If @var{item} is a string, the result is
4174 @code{\once\override} for the specified grob type. If @var{item} is
4175 a music expression, the result is the same music expression with an
4176 appropriate tweak applied.
4178 In other words, the @code{\shape} function can act as either a
4179 @code{\once\override} command or a @code{\tweak} command depending
4180 on whether the @var{item} argument is a grob name, like @qq{Slur},
4181 or a music expression, like @qq{(}. The @var{displacements} argument
4182 specifies the displacements of the four control points as a list of
4183 four pairs of (dx . dy) values in units of staff-spaces (or a list
4184 of such lists if the curve has more than one segment).
4186 The leading hyphen is required if and only if the @code{\tweak} form
4189 So, using the same example as above and the @code{\once\override}
4190 form of @code{\shape}, this will raise the tie by half a staff-space:
4192 @lilypond[verbatim,quote,relative=1]
4195 \shape #'((0 . 0.5) (0 . 0.5) (0 . 0.5) (0 . 0.5)) Tie
4199 { r4 <g c,> <g c,> <g c,> }
4203 This positioning of the tie is better, but maybe it should be raised
4204 more in the center. The following example does this, this time using
4205 the alternative @code{\tweak} form:
4207 @lilypond[verbatim,quote,relative=1]
4210 e1-\shape #'((0 . 0.5) (0 . 1) (0 . 1) (0 . 0.5)) ~ e
4213 { r4 <g c,> <g c,> <g c,> }
4217 Changes to the horizontal positions of the control points may be made
4218 in the same way, and two different curves starting at the same
4219 musical moment may also be shaped:
4221 @lilypond[verbatim,quote,ragged-right,relative=2]
4223 \shape #'((0.7 . -0.4) (0.5 . -0.4) (0.3 . -0.3) (0 . -0.2)) Slur
4224 \shape #'((0 . 0) (0 . 0.5) (0 . 0.5) (0 . 0)) PhrasingSlur
4228 The @code{\shape} function can also displace the control points of
4229 curves which stretch across line breaks. Each piece of the broken
4230 curve can be given its own list of offsets. If changes to a
4231 particular segment are not needed, the empty list can serve as a
4232 placeholder. In this example the line break makes the single slur
4235 @lilypond[verbatim,quote,ragged-right,relative=1]
4241 Changing the shapes of the two halves of the slur makes it clearer
4242 that the slur continues over the line break:
4244 @lilypond[verbatim,quote,ragged-right,relative=1]
4245 % () may be used as a shorthand for ((0 . 0) (0 . 0) (0 . 0) (0 . 0))
4246 % if any of the segments does not need to be changed
4248 (( 0 . 0) (0 . 0) (0 . 0) (0 . 1))
4249 ((0.5 . 1.5) (1 . 0) (0 . 0) (0 . -1.5))
4256 If an S-shaped curve is required the control points must always be
4257 adjusted manually --- LilyPond will never select such shapes
4260 @lilypond[verbatim,quote,relative=2]
4261 c8( e b-> f d' a e-> g)
4262 \shape #'((0 . -1) (5.5 . -0.5) (-5.5 . -10.5) (0 . -5.5)) PhrasingSlur
4263 c8\( e b-> f d' a e-> g\)
4266 @subsubsubheading Specifying control points explicitly
4268 The coordinates of the Bézier control points are specified in units
4269 of staff-spaces. The X@tie{}coordinate is relative to the reference
4270 point of the note to which the tie or slur is attached, and the
4271 Y@tie{}coordinate is relative to the staff center line. The
4272 coordinates are specified as a list of four pairs of decimal numbers
4273 (reals). One approach is to estimate the coordinates of the two
4274 end points, and then guess the two intermediate points. The optimum
4275 values are then found by trial and error. Be aware that these values
4276 may need to be manually adjusted if any further changes are made to
4277 the music or the layout.
4279 One situation where specifying the control points explicitly is
4280 preferable to specifying displacements is when they need to be
4281 specified relative to a single note. Here is an example of this.
4282 It shows one way of indicating a slur extending into alternative
4283 sections of a volta repeat.
4285 @lilypond[verbatim,quote,relative=2]
4287 \repeat volta 3 { c4 d( e f }
4292 % create a slur and move it to a new position
4293 % the <> is just an empty chord to carry the slur termination
4294 -\tweak control-points #'((-2 . 3.8) (-1 . 3.9) (0 . 4) (1 . 3.4)) ( <> )
4299 % create a slur and move it to a new position
4300 -\tweak control-points #'((-2 . 3) (-1 . 3.1) (0 . 3.2) (1 . 2.4)) ( <> )
4307 It is not possible to modify shapes of ties or slurs by changing
4308 the @code{control-points} property if there are multiple ties or slurs
4309 at the same musical moment -- the @code{\tweak} command will also not
4310 work in this case. However, the @code{tie-configuration} property of
4311 @code{TieColumn} can be overridden to set start line and direction as
4315 Internals Reference:
4316 @rinternals{TieColumn}.
4319 @node Unpure-pure containers
4320 @subsection Unpure-pure containers
4322 @cindex Scheme, pure containers
4323 @cindex Scheme, unpure containers
4324 @cindex pure containers, Scheme
4325 @cindex unpure containers, Scheme
4326 @cindex horizontal spacing, overriding
4328 Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
4329 calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
4330 Scheme function instead of a literal (i.e. a number or pair).
4332 For certain grobs, the @code{Y-extent} is based on the @code{stencil}
4333 property, overriding the stencil property of one of these will
4334 require an additional @code{Y-extent} override with an unpure-pure
4335 container. When a function overrides a @code{Y-offset} and/or
4336 @code{Y-extent} it is assumed that this will trigger line breaking
4337 calculations too early during compilation. So the function is not
4338 evaluated at all (usually returning a value of @samp{0} or
4339 @samp{'(0 . 0)}) which can result in collisions. A @q{pure} function
4340 will not affect properties, objects or grob suicides and therefore will
4341 always have its Y-axis-related evaluated correctly.
4343 Currently, there are about thirty functions that are already considered
4344 @q{pure} and Unpure-pure containers are a way to set functions not on
4345 this list as @q{pure}. The @q{pure} function is evaluated @emph{before}
4346 any line-breaking and so the horizontal spacing can be adjusted
4347 @q{in time}. The @q{unpure} function is then evaluated @emph{after}
4350 @warning{As it is difficult to always know which functions are on this
4351 list we recommend that any @q{pure} functions you create do not use
4352 @code{Beam} or @code{VerticalAlignment} grobs.}
4354 An unpure-pure container is constructed as follows;
4356 @code{(ly:make-unpure-pure-container f0 f1)}
4358 where @code{f0} is a function taking @var{n} arguments (@var{n >= 1})
4359 and the first argument must always be the grob. This is the function
4360 that gives the actual result. @var{f1} is the function being labeled
4361 as @q{pure} that takes @var{n + 2} arguments. Again, the first argument
4362 must always still be the grob but the second and third are @q{start}
4363 and @q{end} arguments.
4365 @var{start} and @var{end} are, for all intents and purposes, dummy
4366 values that only matter for @code{Spanners} (i.e @code{Hairpin} or
4367 @code{Beam}), that can return different height estimations based on a
4368 starting and ending column.
4370 The rest are the other arguments to the first function (which
4371 may be none if @var{n = 1}).
4373 The results of the second function are used as an approximation of the
4374 value needed which is then used by the first function to get the real
4375 value which is then used for fine-tuning much later during the spacing
4378 @lilypond[verbatim,quote,ragged-right]
4379 #(define (square-line-circle-space grob)
4380 (let* ((pitch (ly:event-property (ly:grob-property grob 'cause) 'pitch))
4381 (notename (ly:pitch-notename pitch)))
4382 (if (= 0 (modulo notename 2))
4383 (make-circle-stencil 0.5 0.0 #t)
4384 (make-filled-box-stencil '(0 . 1.0)
4387 squareLineCircleSpace = {
4388 \override NoteHead.stencil = #square-line-circle-space
4391 smartSquareLineCircleSpace = {
4392 \squareLineCircleSpace
4393 \override NoteHead.Y-extent =
4394 #(ly:make-unpure-pure-container
4395 ly:grob::stencil-height
4396 (lambda (grob start end) (ly:grob::stencil-height grob)))
4399 \new Voice \with { \remove "Stem_engraver" }
4401 \squareLineCircleSpace
4403 \smartSquareLineCircleSpace
4408 In the first measure, without the unpure-pure container, the spacing
4409 engine does not know the width of the note head and lets it collide with
4410 the accidentals. In the second measure, with unpure-pure containers,
4411 the spacing engine knows the width of the note heads and avoids the
4412 collision by lengthening the line accordingly.
4414 Usually for simple calculations nearly-identical functions for both the
4415 @q{unpure} and @q{pure} parts can be used, by only changing the number
4416 of arguments passed to, and the scope of, the function.
4418 @warning{If a function is labeled as @q{pure} and it turns out not to
4419 be, the results can be unexpected.}
4422 @node Using music functions
4423 @section Using music functions
4425 @c TODO -- add @seealso, etc. to these subsections
4427 Where tweaks need to be reused with different music expressions,
4428 it is often convenient to make the tweak part of a @emph{music
4429 function}. In this section, we discuss only @emph{substitution}
4430 functions, where the object is to substitute a variable into a
4431 piece of LilyPond input code. Other more complex functions are
4432 described in @rextend{Music functions}.
4435 * Substitution function syntax::
4436 * Substitution function examples::
4439 @node Substitution function syntax
4440 @subsection Substitution function syntax
4442 Making a function that substitutes a variable into LilyPond
4443 code is easy. The general form of these functions is
4447 #(define-music-function
4448 (parser location @var{arg1} @var{arg2} @dots{})
4449 (@var{type1?} @var{type2?} @dots{})
4451 @var{@dots{}music@dots{}}
4458 @multitable @columnfractions .33 .66
4459 @item @code{@var{argN}}
4460 @tab @var{n}th argument
4462 @item @code{@var{typeN?}}
4463 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
4464 must return @code{#t}.
4466 @item @code{@var{@dots{}music@dots{}}}
4467 @tab normal LilyPond input, using @code{$} (in places where only
4468 Lilypond constructs are allowed) or @code{#} (to use it as a Scheme
4469 value or music function argument or music inside of music lists) to
4474 The @code{parser} and @code{location} arguments are mandatory, and
4475 are used in some advanced situations as described in the
4476 @q{Extending} manual (see @rextend{Music functions}). For
4477 substitution functions, just be sure to include them.
4479 The list of type predicates is also required. Some of the most
4480 common type predicates used in music functions are:
4484 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
4496 For a list of available type predicates, see
4497 @ref{Predefined type predicates}. User-defined type predicates
4502 @ref{Predefined type predicates}.
4505 @rextend{Music functions}.
4508 @file{lily/music-scheme.cc},
4510 @file{scm/lily.scm}.
4513 @node Substitution function examples
4514 @subsection Substitution function examples
4516 This section introduces some substitution function examples.
4517 These are not intended to be exhaustive, but rather to demonstrate
4518 some of the possibilities of simple substitution functions.
4520 In the first example, a function is defined that simplifies
4521 setting the padding of a TextScript:
4523 @lilypond[quote,verbatim,ragged-right]
4525 #(define-music-function
4526 (parser location padding)
4529 \once \override TextScript.padding = #padding
4533 c4^"piu mosso" b a b
4535 c4^"piu mosso" b a b
4537 c4^"piu mosso" b a b
4541 In addition to numbers, we can use music expressions such
4542 as notes for arguments to music functions:
4544 @lilypond[quote,verbatim,ragged-right]
4546 #(define-music-function
4547 (parser location note)
4550 \tweak NoteHead.stencil #ly:text-interface::print
4551 \tweak NoteHead.text
4552 \markup \musicglyph #"custodes.mensural.u0"
4553 \tweak Stem.stencil ##f
4557 \relative c' { c4 d e f \custosNote g }
4560 Substitution functions with multiple arguments can be defined:
4562 @lilypond[quote,verbatim,ragged-right]
4564 #(define-music-function
4565 (parser location padding tempotext)
4568 \once \override Score.MetronomeMark.padding = #padding
4569 \tempo \markup { \bold #tempotext }
4573 \tempo \markup { "Low tempo" }
4575 \tempoPadded #4.0 "High tempo"
4580 @c TODO: add appropriate @@ref's here.