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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 when engraving; the notes are printed on one line. The MIDI
218 rendition retains pitches unchanged.
220 @strong{@emph{TabStaff}}
222 Context for generating tablature. By default lays the music
223 expression out as a guitar tablature, printed on six lines.
225 @strong{@emph{DrumStaff}}
227 Handles typesetting for percussion. Can contain @code{DrumVoice}
229 @strong{@emph{VaticanaStaff}}
231 Same as @code{Staff}, except that it is designed for typesetting
232 a piece in gregorian style.
234 @strong{@emph{MensuralStaff}}
236 Same as @code{Staff}, except that it is designed for typesetting
237 a piece in mensural style.
239 @node Bottom-level contexts - voices
240 @unnumberedsubsubsec Bottom-level contexts - voices
242 Voice-level contexts initialise certain properties and start
243 appropriate engravers. A bottom-level context is one without
244 @code{defaultchild}. While it is possible to let it
245 accept/@/contain subcontexts, they can only be created and entered
248 @strong{@emph{Voice}}
250 Corresponds to a voice on a staff. This context handles the
251 conversion of dynamic signs, stems, beams, super- and sub-scripts,
252 slurs, ties, and rests. You have to instantiate this explicitly
253 if you require multiple voices on the same staff.
255 @strong{@emph{VaticanaVoice}}
257 Same as @code{Voice}, except that it is designed for typesetting
258 a piece in gregorian style.
260 @strong{@emph{MensuralVoice}}
262 Same as @code{Voice}, with modifications for typesetting a piece in
265 @strong{@emph{Lyrics}}
267 Corresponds to a voice with lyrics. Handles the printing of a
268 single line of lyrics.
270 @strong{@emph{DrumVoice}}
272 The voice context used in a percussion staff.
274 @strong{@emph{FiguredBass}}
276 The context in which @code{BassFigure} objects are created from
277 input entered in @code{\figuremode} mode.
279 @strong{@emph{TabVoice}}
281 The voice context used within a @code{TabStaff} context. Usually
282 left to be created implicitly.
284 @strong{@emph{CueVoice}}
286 A voice context used to render notes of a reduced size, intended
287 primarily for adding cue notes to a staff, see @ref{Formatting
288 cue notes}. Usually left to be created implicitly.
290 @strong{@emph{ChordNames}}
292 Typesets chord names.
297 Then the following, which I don't know what to do with:
299 * GregorianTranscriptionVoice
300 * GregorianTranscriptionStaff
303 Engraves fretboards from chords. Not easy... Not
305 There is now some documentation on FretBoards in the NR, under
306 instrument-specific notation -- cds.
311 Hard coded entry point for LilyPond. Cannot be tuned.
313 Silently discards all musical information given to this
318 @node Creating and referencing contexts
319 @subsection Creating and referencing contexts
324 @cindex referencing contexts
325 @cindex Contexts, creating and referencing
327 LilyPond will create lower-level contexts automatically if a music
328 expression is encountered before a suitable context exists, but this
329 is usually successful only for simple scores or music fragments like
330 the ones in the documentation. For more complex scores it is
331 advisable to specify all contexts explicitly with either the
332 @code{\new} or @code{\context} command. The syntax of
333 these two commands is very similar:
336 [\new | \context] @var{Context} [ = @var{name}] [@var{music-expression}]
340 where either @code{\new} or @code{\context} may be specified.
341 @var{Context} is the type of context which is to be created,
342 @var{name} is an optional name to be given to the particular context
343 being created and @var{music-expression} is a single music expression
344 that is to be interpreted by the engravers and performers in this
347 The @code{\new} prefix without a name is commonly used to create
348 scores with many staves:
350 @lilypond[quote,verbatim]
352 \new Staff \relative {
353 % leave the Voice context to be created implicitly
356 \new Staff \relative {
363 and to place several voices into one staff:
365 @lilypond[quote,verbatim]
367 \new Voice \relative {
371 \new Voice \relative {
379 @code{\new} should always be used to specify unnamed contexts.
381 The difference between @code{\new} and @code{\context} is in the
386 @code{\new} with or without a name will always create a fresh,
387 distinct, context, even if one with the same name already exists:
389 @lilypond[quote,verbatim]
391 \new Voice = "A" \relative {
395 \new Voice = "A" \relative {
403 @code{\context} with a name specified will create a distinct context
404 only if a context of the same type with the same name in the same
405 context hierarchy does not already exist. Otherwise it will be taken
406 as a reference to that previously created context, and its music
407 expression will be passed to that context for interpretation.
409 One application of named contexts is in separating the score layout
410 from the musical content. Either of these two forms is valid:
412 @lilypond[quote,verbatim]
426 \context Voice = "one" {
431 \context Voice = "two" {
440 @lilypond[quote,verbatim]
445 \context Voice = "one" {
448 \context Voice = "two" {
454 \context Voice = "one" {
459 \context Voice = "two" {
469 Alternatively, variables may be employed to similar effect. See
470 @rlearning{Organizing pieces with variables}.
473 @code{\context} with no name will match the first of any previously
474 created contexts of the same type in the same context heirarchy,
475 even one that has been given a name, and its music expression will be
476 passed to that context for interpretation. This form is rarely
477 useful. However, @code{\context} with no name and no music expression
478 is used to set the context in which a Scheme procedure specified with
479 @code{\applyContext} is executed:
482 \new Staff \relative @{
485 \applyContext #(lambda (ctx)
487 (display (ly:context-current-moment ctx)))
494 A context must be named if it is to be referenced later, for example
495 when lyrics are associated with music:
498 \new Voice = "tenor" @var{music}
500 \new Lyrics \lyricsto "tenor" @var{lyrics}
504 For details of associating lyrics with music see
505 @ref{Automatic syllable durations}.
507 The properties of all contexts of a particular type can be modified
508 in a @code{\layout} block (with a different syntax), see
509 @ref{Changing all contexts of the same type}. This construct also
510 provides a means of keeping layout instructions separate from the
511 musical content. If a single context is to be modified, a @code{\with}
512 block must be used, see @ref{Changing just one specific context}.
516 @rlearning{Organizing pieces with variables}.
519 @ref{Changing just one specific context},
520 @ref{Automatic syllable durations}.
523 @node Keeping contexts alive
524 @subsection Keeping contexts alive
526 @cindex contexts, keeping alive
527 @cindex contexts, lifetime
529 Contexts are usually terminated at the first musical moment in
530 which they have nothing to do. So @code{Voice} contexts die as
531 soon as they contain no events; @code{Staff} contexts die as soon
532 as all the @code{Voice} contexts within them contain no events; etc.
533 This can cause difficulties if earlier contexts which have died
534 have to be referenced, for example, when changing staves with
535 @code{\change} commands, associating lyrics with a voice with
536 @code{\lyricsto} commands, or when adding further musical events to
539 There is an exception to this general rule: just one of the
540 @code{Voice} contexts in a @code{Staff} context or in a
541 @code{<<@dots{}>>} construct will always persist to the end of the
542 enclosing @code{Staff} context or @code{<<@dots{}>>} construct, even
543 though there may be periods when it has nothing to do. The context
544 to persist in this way will be the first one encountered in the
545 first enclosed @code{@{@dots{}@}} construct, ignoring any in enclosed
546 @code{<<@dots{}>>} constructs.
548 Any context can be kept alive by ensuring it has something to do at
549 every musical moment. @code{Staff} contexts are kept alive by
550 ensuring one of their voices is kept alive. One way of doing this
551 is to add spacer rests to a voice in parallel with the real music.
552 These need to be added to every @code{Voice} context which needs to
553 be kept alive. If several voices are to be used sporadically it is
554 safest to keep them all alive rather than attempting to rely on the
555 exceptions mentioned above.
557 In the following example, both voice A and voice B are kept alive
558 in this way for the duration of the piece:
560 @lilypond[quote,verbatim]
561 musicA = \relative { d''4 d d d }
562 musicB = \relative { g'4 g g g }
565 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
566 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
571 \context Voice = "A" {
575 \context Voice = "B" {
579 \context Voice = "A" { \musicA }
580 \context Voice = "B" { \musicB }
581 \context Voice = "A" { \musicA }
592 @cindex lyrics, aligning with sporadic melody
594 The following example shows how a sporadic melody line with lyrics
595 might be written using this approach. In a real situation the
596 melody and accompaniment would consist of several different
599 @lilypond[quote,verbatim]
600 melody = \relative { a'4 a a a }
601 accompaniment = \relative { d'4 d d d }
602 words = \lyricmode { These words fol -- low the mel -- o -- dy }
605 \new Staff = "music" {
607 \new Voice = "melody" {
609 s1*4 % Keep Voice "melody" alive for 4 bars
612 \new Voice = "accompaniment" {
617 \context Voice = "melody" { \melody }
618 \context Voice = "accompaniment" { \accompaniment }
620 \context Voice = "accompaniment" { \accompaniment }
622 \context Voice = "melody" { \melody }
623 \context Voice = "accompaniment" { \accompaniment }
628 \new Lyrics \with { alignAboveContext = #"music" }
629 \lyricsto "melody" { \words }
634 An alternative way, which may be better in many circumstances, is
635 to keep the melody line alive by simply including spacer notes to
636 line it up correctly with the accompaniment:
638 @lilypond[quote,verbatim]
645 accompaniment = \relative {
651 words = \lyricmode { These words fol -- low the mel -- o -- dy }
655 \new Staff = "music" {
657 \new Voice = "melody" {
661 \new Voice = "accompaniment" {
667 \new Lyrics \with { alignAboveContext = #"music" }
668 \lyricsto "melody" { \words }
674 @node Modifying context plug-ins
675 @subsection Modifying context plug-ins
677 @c TODO Should this be Modifying engravers or Modifying contexts?
679 Notation contexts (like @code{Score} and @code{Staff}) not only store
680 properties, they also contain plug-ins called @q{engravers} that create
681 notation elements. For example, the @code{Voice} context contains a
682 @code{Note_heads_engraver} and the @code{Staff} context contains a
685 For a full a description of each plug-in, see
687 @rinternals{Engravers and Performers}.
690 Internals Reference @expansion{} Translation @expansion{} Engravers.
692 Every context described in
694 @rinternals{Contexts}
697 Internals Reference @expansion{} Translation @expansion{} Context.
699 lists the engravers used for that context.
702 It can be useful to shuffle around these plug-ins. This is done by
703 starting a new context with @code{\new} or @code{\context}, and
709 \new @var{context} \with @{
717 @emph{@dots{}music@dots{}}
722 where the @dots{} should be the name of an engraver. Here is a simple
723 example which removes @code{Time_signature_engraver} and
724 @code{Clef_engraver} from a @code{Staff} context,
726 @lilypond[quote,verbatim]
728 \new Staff \relative {
732 \remove "Time_signature_engraver"
733 \remove "Clef_engraver"
740 In the second staff there are no time signature or clef symbols. This
741 is a rather crude method of making objects disappear since it will affect
742 the entire staff. This method also influences the spacing, which may or
743 may not be desirable. More sophisticated methods of blanking objects
744 are shown in @rlearning{Visibility and color of objects}.
746 The next example shows a practical application. Bar lines and time
747 signatures are normally synchronized across the score. This is done
748 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
749 This plug-in keeps an administration of time signature, location
750 within the measure, etc. By moving these engraver from @code{Score} to
751 @code{Staff} context, we can have a score where each staff has its own
754 @cindex polymetric scores
755 @cindex time signature, multiple
757 @lilypond[quote,verbatim]
761 \consists "Timing_translator"
762 \consists "Default_bar_line_engraver"
769 \consists "Timing_translator"
770 \consists "Default_bar_line_engraver"
780 \remove "Timing_translator"
781 \remove "Default_bar_line_engraver"
789 The order in which the engravers are specified is the order in
790 which they are called to carry out their processing. Usually the
791 order in which the engravers are specified does not matter, but in
792 a few special cases the order is important, for example where one
793 engraver writes a property and another reads it, or where one
794 engraver creates a grob and another must process it.
796 The following orderings are important:
800 the @code{Bar_engraver} must normally be first,
803 the @code{New_fingering_engraver} must come before the
804 @code{Script_column_engraver},
807 the @code{Timing_translator} must come before the
808 @code{Bar_number_engraver}.
814 @file{ly/engraver-init.ly}.
817 @node Changing context default settings
818 @subsection Changing context default settings
820 @cindex default context properties, changing
821 @cindex context properties, changing defaults
823 Context and grob properties can be changed with @code{\set}
824 and @code{\override} commands, as described in
825 @ref{Modifying properties}. These commands create music events,
826 making the changes take effect at the point in time the music
829 In contrast, this section explains how to change the @emph{default}
830 values of context and grob properties at the time the context is
831 created. There are two ways of doing this. One modifies the default
832 values in all contexts of a particular type, the other modifies the
833 default values in just one particular instance of a context.
836 * Changing all contexts of the same type::
837 * Changing just one specific context::
838 * Order of precedence::
841 @node Changing all contexts of the same type
842 @unnumberedsubsubsec Changing all contexts of the same type
844 @cindex \context in \layout block
848 The default context settings which are to be used for typesetting in
849 @code{Score}, @code{Staff}, @code{Voice} and other contexts may be
850 specified in a @code{\context} block within any @code{\layout}
853 Settings for Midi output as opposed to typesetting will have to be
854 separately specified in @code{\midi} blocks (see @ref{Output
855 definitions - blueprints for contexts}).
857 The @code{\layout} block should be placed within the @code{\score}
858 block to which it is to apply, after the music.
864 [context settings for all Voice contexts]
868 [context settings for all Staff contexts]
873 The following types of settings may be specified:
877 An @code{\override} command, but with the context name omitted
879 @lilypond[quote,verbatim]
882 a'4^"Thicker stems" a a a
888 \override Stem.thickness = #4.0
895 Directly setting a context property
897 @lilypond[quote,verbatim]
900 a'4^"Smaller font" a a a
913 A predefined command such as @code{\dynamicUp} or a music
914 expression like @code{\accidentalStyle dodecaphonic}
916 @lilypond[quote,verbatim]
919 a'4^"Dynamics above" a a a
929 \accidentalStyle dodecaphonic
936 A user-defined variable containing a @code{\with} block; for details
937 of the @code{\with} block see
938 @ref{Changing just one specific context}.
940 @lilypond[quote,verbatim]
941 StaffDefaults = \with {
948 a'4^"Smaller font" a a a
963 Property-setting commands can be placed in a @code{\layout} block
964 without being enclosed in a @code{\context} block. Such settings
965 are equivalent to including the same property-setting commands at
966 the start of every context of the type specified. If no context
967 is specified @emph{every} bottom-level context is affected, see
968 @ref{Bottom-level contexts - voices}. The syntax of a
969 property-setting command in a @code{\layout} block is the same as
970 the same command written in the music stream.
972 @lilypond[quote,verbatim]
976 a'4^"Smaller font" a a a
981 \accidentalStyle dodecaphonic
983 \override Voice.Stem.thickness = #4.0
989 @node Changing just one specific context
990 @unnumberedsubsubsec Changing just one specific context
995 The context properties of just one specific context instance can be
996 changed in a @code{\with} block. All other context instances of the
997 same type retain the default settings built into LilyPond and modified
998 by any @code{\layout} block within scope. The @code{\with} block
999 must be placed immediately after the @code{\new} @var{context-type}
1003 \new Staff \with @{ [context settings for this context instance only] @}
1009 Since such a @q{context modification} is specified inside of
1010 music, it will affect @emph{all} outputs (typesetting @emph{and}
1011 Midi) as opposed to changes within an output definition.
1013 The following types of settings may be specified:
1017 An @code{\override} command, but with the context name omitted
1019 @lilypond[quote,verbatim]
1022 \new Voice \with { \override Stem.thickness = #4.0 }
1025 a'4^"Thick stems" a a a
1034 Directly setting a context property
1036 @lilypond[quote,verbatim]
1041 a'4^"Default font" a a a
1045 \new Staff \with { fontSize = #-4 }
1048 a'4^"Smaller font" a a a
1057 A predefined command such as @code{\dynamicUp}
1059 @lilypond[quote,verbatim]
1065 a'4^"Dynamics below" a a a
1070 \new Staff \with { \accidentalStyle dodecaphonic }
1072 \new Voice \with { \dynamicUp }
1075 a'4^"Dynamics above" a a a
1086 @node Order of precedence
1087 @unnumberedsubsubsec Order of precedence
1089 The value of a property which applies at a particular time is
1090 determined as follows:
1094 if an @code{\override} or @code{\set} command in the input stream is
1095 in effect that value is used,
1098 otherwise the default value taken from a @code{\with} statement
1099 on the context initiation statement is used,
1102 otherwise the default value taken from the most recent appropriate
1103 @code{\context} block in the @code{\layout} or @code{\midi} blocks
1107 otherwise the LilyPond built-in default is used.
1112 @rlearning{Modifying context properties}.
1115 @ref{Contexts explained},
1116 @ref{Bottom-level contexts - voices},
1117 @ref{The set command},
1118 @ref{The override command},
1119 @ref{The layout block,,The @code{@bs{}layout} block}.
1122 @node Defining new contexts
1123 @subsection Defining new contexts
1125 @cindex contexts, defining new
1126 @cindex engravers, including in contexts
1141 Specific contexts, like @code{Staff} and @code{Voice}, are made from
1142 simple building blocks. It is possible to create new types of
1143 contexts with different combinations of engraver plug-ins.
1145 The next example shows how to build a different type of
1146 @code{Voice} context from scratch. It will be similar to
1147 @code{Voice}, but only prints centered slash note heads. It can be used
1148 to indicate improvisation in jazz pieces,
1150 @lilypond[quote,ragged-right]
1151 \layout { \context {
1153 \type "Engraver_group"
1154 \consists "Note_heads_engraver"
1155 \consists "Rhythmic_column_engraver"
1156 \consists "Text_engraver"
1157 \consists "Pitch_squash_engraver"
1158 squashedPosition = #0
1159 \override NoteHead.style = #'slash
1164 \accepts "ImproVoice"
1168 a'4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1169 c4 c^"undress" c_"while playing :)" c }
1175 These settings are defined within a @code{\context} block inside a
1176 @code{\layout} block,
1186 In the following discussion, the example input shown should go in place
1187 of the @dots{} in the previous fragment.
1189 First it is necessary to define a name for the new context:
1195 Since it is similar to the @code{Voice} context, we want commands that
1196 work in (existing) @code{Voice} contexts to continue working. This is
1197 achieved by giving the new context an alias of @code{Voice},
1203 The context will print notes and instructive texts, so we need to add
1204 the engravers which provide this functionality, plus the engraver which
1205 groups notes, stems and rests which occur at the same musical moment
1209 \consists "Note_heads_engraver"
1210 \consists "Text_engraver"
1211 \consists "Rhythmic_column_engraver"
1214 The note heads should all be placed on the center line,
1217 \consists "Pitch_squash_engraver"
1218 squashedPosition = #0
1221 The @code{Pitch_squash_engraver} modifies note heads (created
1222 by the @code{Note_heads_engraver}) and sets their vertical
1223 position to the value of @code{squashedPosition}, in this
1224 case@tie{}@code{0}, the center line.
1226 The notes look like a slash, and have no stem,
1229 \override NoteHead.style = #'slash
1233 All these plug-ins have to communicate under the control of the
1234 context. The mechanisms with which contexts communicate are
1235 established by declaring the context @code{\type}. Within a
1236 @code{\layout} block, most contexts will be of type
1237 @code{Engraver_group}. Some special contexts and contexts in
1238 @code{\midi} blocks use other context types. Copying and
1239 modifying an existing context definition will also fill in the
1240 type. Since this example creates a definition from scratch, it
1241 needs to be specified explicitly.
1244 \type "Engraver_group"
1247 Put together, we get
1252 \type "Engraver_group"
1253 \consists "Note_heads_engraver"
1254 \consists "Text_engraver"
1255 \consists "Rhythmic_column_engraver"
1256 \consists "Pitch_squash_engraver"
1257 squashedPosition = #0
1258 \override NoteHead.style = #'slash
1265 Contexts form hierarchies. We want to place the @code{ImproVoice}
1266 context within the @code{Staff} context, just like normal @code{Voice}
1267 contexts. Therefore, we modify the @code{Staff} definition with the
1268 @code{\accepts} command,
1277 @funindex \inherit-acceptability
1278 Often when reusing an existing context definition, the resulting
1279 context can be used anywhere where the original context would have
1285 \inherit-acceptability @var{to} @var{from}
1290 will arrange to have contexts of type @var{to} accepted by all
1291 contexts also accepting @var{from}. For example, using
1296 \inherit-acceptability "ImproVoice" "Voice"
1301 will add an @code{\accepts} for @code{ImproVoice} to both
1302 @code{Staff} and @code{RhythmicStaff} definitions.
1305 The opposite of @code{\accepts} is @code{\denies},
1306 which is sometimes needed when reusing existing context definitions.
1308 Arranging the required pieces into a @code{\layout} block leaves
1317 \inherit-acceptability "ImproVoice" "Voice"
1321 Then the output at the start of this subsection can be entered as
1329 c c_"while playing :)"
1335 To complete this example, changes affecting the context hierarchy
1336 should be repeated in a @code{\midi} block so that Midi output
1337 depends on the same context relations.
1341 Internals Reference:
1342 @rinternals{Note_heads_engraver},
1343 @rinternals{Text_engraver},
1344 @rinternals{Rhythmic_column_engraver},
1345 @rinternals{Pitch_squash_engraver}.
1348 @node Context layout order
1349 @subsection Context layout order
1351 @cindex contexts, layout order
1355 Contexts are normally positioned in a system from top to bottom
1356 in the order in which they are encountered in the input file. When
1357 contexts are nested, the outer context will include inner nested
1358 contexts as specified in the input file, provided the inner contexts
1359 are included in the outer context's @qq{accepts} list. Nested
1360 contexts which are not included in the outer context's @qq{accepts}
1361 list will be repositioned below the outer context rather than nested
1364 The @qq{accepts} list of a context can be changed with the
1365 @code{\accepts} or @code{\denies} commands. @code{\accepts} adds a
1366 context to the @qq{accepts} list and @code{\denies} removes a context
1369 For example, a square-braced staff group is not usually found within a
1370 curved-braced staff with connecting staff bars, and a @code{GrandStaff}
1371 does not accept a @code{StaffGroup} inside it by default.
1373 @lilypond[verbatim,quote]
1380 \new Staff { \set Staff.instrumentName = bottom f'1 }
1385 However, by using the @code{\accepts} command, @code{StaffGroup} can be
1386 added to the @code{GrandStaff} context:
1388 @lilypond[verbatim,quote]
1395 \new Staff { \set Staff.instrumentName = bottom f'1 }
1400 \accepts "StaffGroup"
1406 @code{\denies} is mainly used when a new context is being based on
1407 another, but the required nesting differs. For example, the
1408 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1409 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1410 context in the @qq{accepts} list.
1412 @cindex contexts, implicit
1413 @cindex implicit contexts
1414 @funindex \defaultchild
1416 Note that a context will be silently created implicitly if a
1417 command is encountered when there is no suitable context available
1420 Within a context definition, the type of subcontext to be
1421 implicitly created is specified using @code{\defaultchild}. A
1422 number of music events require a @samp{Bottom} context: when such
1423 an event is encountered, subcontexts are created recursively until
1424 reaching a context with no @samp{defaultchild} setting.
1426 Implicit context creation can at times give rise to unexpected new
1427 staves or scores. Using @code{\new} to create contexts explicitly
1428 avoids those problems.
1430 @cindex alignAboveContext
1431 @cindex alignBelowContext
1432 @funindex alignAboveContext
1433 @funindex alignBelowContext
1435 Sometimes a context is required to exist for just a brief period, a
1436 good example being the staff context for an ossia. This is usually
1437 achieved by introducing the context definition at the appropriate
1438 place in parallel with corresponding section of the main music.
1439 By default, the temporary context will be placed below all the
1440 existing contexts. To reposition it above the context called
1441 @qq{main}, it should be defined like this:
1444 @code{\new Staff \with @{ alignAboveContext = #"main" @} }
1447 A similar situation arises when positioning a temporary lyrics
1448 context within a multi-staved layout such as a @code{ChoirStaff},
1449 for example, when adding a second verse to a repeated section.
1450 By default the temporary lyrics context will be placed beneath the
1451 lower staves. By defining the temporary lyrics context with
1452 @code{alignBelowContext} it can be positioned correctly beneath
1453 the (named) lyrics context containing the first verse.
1455 Examples showing this repositioning of temporary contexts can be
1456 found elsewhere --- see @rlearning{Nesting music expressions},
1457 @ref{Modifying single staves} and @ref{Techniques specific to lyrics}.
1461 @rlearning{Nesting music expressions}.
1464 @ref{Modifying single staves},
1465 @ref{Techniques specific to lyrics}.
1468 @rprogram{An extra staff appears}.
1471 @file{ly/engraver-init.ly}.
1474 @node Explaining the Internals Reference
1475 @section Explaining the Internals Reference
1478 * Navigating the program reference::
1479 * Layout interfaces::
1480 * Determining the grob property::
1481 * Naming conventions::
1484 @node Navigating the program reference
1485 @subsection Navigating the program reference
1487 @c TODO remove this (it's in the LM)
1488 @c Replace with more factual directions
1490 Suppose we want to move the fingering indication in the fragment
1493 @lilypond[quote,fragment,verbatim]
1497 If you visit the documentation on fingering instructions (in
1498 @ref{Fingering instructions}), you will notice:
1503 Internals Reference: @rinternals{Fingering}.
1508 @c outdated info; probably will delete.
1510 This fragment points to two parts of the program reference: a page
1511 on @code{FingeringEvent} and one on @code{Fingering}.
1513 The page on @code{FingeringEvent} describes the properties of the music
1514 expression for the input @w{@code{-2}}. The page contains many links
1515 forward. For example, it says
1518 Accepted by: @rinternals{Fingering_engraver},
1522 That link brings us to the documentation for the Engraver, the
1526 This engraver creates the following layout objects: @rinternals{Fingering}.
1529 In other words, once the @code{FingeringEvent}s are interpreted, the
1530 @code{Fingering_engraver} plug-in will process them.
1534 @c I can't figure out what this is supposed to mean. -gp
1536 The @code{Fingering_engraver} is also listed to create
1537 @rinternals{Fingering} objects,
1539 @c old info? it doesn't make any sense to me with our current docs.
1541 second bit of information listed under @b{See also} in the Notation
1546 The programmer's reference is available as an HTML document. It is
1547 highly recommended that you read it in HTML form, either online or
1548 by downloading the HTML documentation. This section will be much more
1549 difficult to understand if you are using the
1553 Follow the link to @rinternals{Fingering}. At the top of the
1557 Fingering objects are created by: @rinternals{Fingering_engraver} and
1558 @rinternals{New_fingering_engraver}.
1561 By following related links inside the program reference, we can follow the
1562 flow of information within the program:
1566 @item @rinternals{Fingering}:
1567 @rinternals{Fingering} objects are created by:
1568 @rinternals{Fingering_engraver}
1570 @item @rinternals{Fingering_engraver}:
1571 Music types accepted: @rinternals{fingering-event}
1573 @item @rinternals{fingering-event}:
1574 Music event type @code{fingering-event} is in Music expressions named
1575 @rinternals{FingeringEvent}
1578 This path goes against the flow of information in the program: it
1579 starts from the output, and ends at the input event. You could
1580 also start at an input event, and read with the flow of
1581 information, eventually ending up at the output object(s).
1583 The program reference can also be browsed like a normal document. It
1584 contains chapters on
1586 @rinternals{Music definitions},
1589 @code{Music definitions}
1591 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1592 chapter lists all the definitions used and all properties that may be
1596 @node Layout interfaces
1597 @subsection Layout interfaces
1599 @cindex interface, layout
1600 @cindex layout interface
1603 The HTML page that we found in the previous section describes the
1604 layout object called @rinternals{Fingering}. Such an object is a
1605 symbol within the score. It has properties that store numbers (like
1606 thicknesses and directions), but also pointers to related objects. A
1607 layout object is also called a @emph{Grob}, which is short for Graphical
1608 Object. For more details about Grobs, see @rinternals{grob-interface}.
1610 The page for @code{Fingering} lists the definitions for the
1611 @code{Fingering} object. For example, the page says
1614 @code{padding} (dimension, in staff space):
1620 which means that the number will be kept at a distance of at least 0.5
1624 Each layout object may have several functions as a notational or
1625 typographical element. For example, the Fingering object
1626 has the following aspects
1630 Its size is independent of the horizontal spacing, unlike slurs or beams.
1633 It is a piece of text. Granted, it is usually a very short text.
1636 That piece of text is typeset with a font, unlike slurs or beams.
1639 Horizontally, the center of the symbol should be aligned to the
1640 center of the note head.
1643 Vertically, the symbol is placed next to the note and the staff.
1646 The vertical position is also coordinated with other superscript
1647 and subscript symbols.
1650 Each of these aspects is captured in so-called @emph{interface}s,
1651 which are listed on the @rinternals{Fingering} page at the bottom
1654 This object supports the following interfaces:
1655 @rinternals{item-interface},
1656 @rinternals{self-alignment-interface},
1657 @rinternals{side-position-interface}, @rinternals{text-interface},
1658 @rinternals{text-script-interface}, @rinternals{font-interface},
1659 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1662 Clicking any of the links will take you to the page of the respective
1663 object interface. Each interface has a number of properties. Some of
1664 them are not user-serviceable (@q{Internal properties}), but others
1667 We have been talking of @emph{the} @code{Fingering} object, but actually it
1668 does not amount to much. The initialization file (see
1669 @rlearning{Other sources of information})
1670 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1675 (avoid-slur . around)
1676 (slur-padding . 0.2)
1677 (staff-padding . 0.5)
1678 (self-alignment-X . 0)
1679 (self-alignment-Y . 0)
1680 (script-priority . 100)
1681 (stencil . ,ly:text-interface::print)
1682 (direction . ,ly:script-interface::calc-direction)
1683 (font-encoding . fetaText)
1684 (font-size . -5) ; don't overlap when next to heads.
1685 (meta . ((class . Item)
1686 (interfaces . (finger-interface
1688 text-script-interface
1690 side-position-interface
1691 self-alignment-interface
1692 item-interface))))))
1696 As you can see, the @code{Fingering} object is nothing more than a
1697 bunch of variable settings, and the webpage in the Internals Reference
1698 is directly generated from this definition.
1701 @node Determining the grob property
1702 @subsection Determining the grob property
1704 @c TODO remove this (it's in the LM)
1705 @c Replace with more factual directions
1707 Recall that we wanted to change the position of the @b{2} in
1709 @lilypond[quote,fragment,verbatim]
1713 Since the @b{2} is vertically positioned next to its note, we have to
1714 meddle with the interface associated with this positioning. This is
1715 done using @code{side-position-interface}. The page for this interface
1719 @code{side-position-interface}
1721 Position a victim object (this one) next to other objects (the
1722 support). The property @code{direction} signifies where to put the
1723 victim object relative to the support (left or right, up or down?)
1728 Below this description, the variable @code{padding} is described as
1733 (dimension, in staff space)
1735 Add this much extra space between objects that are next to each other.
1739 By increasing the value of @code{padding}, we can move the
1740 fingering away from the note head. The following command inserts
1741 3 staff spaces of white
1742 between the note and the fingering:
1744 \once \override Voice.Fingering.padding = #3
1747 Inserting this command before the Fingering object is created,
1748 i.e., before @code{c2}, yields the following result:
1750 @lilypond[quote,fragment,verbatim]
1751 \once \override Voice.Fingering.padding = #3
1756 In this case, the context for this tweak is @code{Voice}. This
1757 fact can also be deduced from the program reference, for the page for
1758 the @rinternals{Fingering_engraver} plug-in says
1761 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1765 @node Naming conventions
1766 @subsection Naming conventions
1768 Another thing that is needed, is an overview of the various naming
1772 @item scheme functions: lowercase-with-hyphens (incl. one-word
1774 @item scheme functions: ly:plus-scheme-style
1775 @item music events, music classes and music properties:
1777 @item Grob interfaces: scheme-style
1778 @item backend properties: scheme-style (but X and Y!)
1779 @item contexts (and MusicExpressions and grobs): Capitalized or
1781 @item context properties: lowercaseFollowedByCamelCase
1783 Capitalized_followed_by_lowercase_and_with_underscores
1786 Questions to be answered:
1788 @item Which of these are conventions and which are rules?
1789 @item Which are rules of the underlying language, and which are
1793 @node Modifying properties
1794 @section Modifying properties
1796 @c TODO change the menu and subsection node names to use
1797 @c backslash once the new macro to handle the refs
1798 @c is available. Need to find and change all refs at
1799 @c the same time. -td
1802 * Overview of modifying properties::
1804 * The override command::
1805 * The tweak command::
1806 * set versus override::
1807 * Modifying alists::
1811 @node Overview of modifying properties
1812 @subsection Overview of modifying properties
1814 Each context is responsible for creating certain types of graphical
1815 objects. The settings used for printing these objects are also stored by
1816 context. By changing these settings, the appearance of objects can be
1819 There are two different kinds of properties stored in contexts:
1820 context properties and grob properties. Context properties are
1821 properties that apply to the context as a whole and control
1822 how the context itself is displayed. In contrast, grob properties
1823 apply to specific grob types that will be displayed in the context.
1825 The @code{\set} and @code{\unset} commands are used to change values
1826 for context properties. The @code{\override} and @code{\revert}
1827 commands are used to change values for grob properties.
1830 The syntax for this is
1833 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1836 Here @var{name} is the name of a graphical object, like
1837 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1838 variable of the formatting system (@q{grob property} or @q{layout
1839 property}). The latter is a symbol, so it must be quoted. The
1840 subsection @ref{Modifying properties}, explains what to fill in
1841 for @var{name}, @var{property}, and @var{value}. Here we only
1842 discuss the functionality of this command.
1847 \override Staff.Stem.thickness = #4.0
1851 makes stems thicker (the default is 1.3, with staff line thickness as a
1852 unit). Since the command specifies @code{Staff} as context, it only
1853 applies to the current staff. Other staves will keep their normal
1854 appearance. Here we see the command in action:
1856 @lilypond[quote,fragment,verbatim]
1858 \override Staff.Stem.thickness = #4.0
1864 The @code{\override} command changes the definition of the @code{Stem}
1865 within the current @code{Staff}. After the command is interpreted
1866 all stems are thickened.
1868 Analogous to @code{\set}, the @var{context} argument may be left out,
1869 causing the default context @code{Voice} to be used. Adding
1870 @code{\once} applies the change during one timestep only.
1872 @lilypond[quote,fragment,verbatim]
1874 \once \override Stem.thickness = #4.0
1879 The @code{\override} must be done before the object is
1880 started. Therefore, when altering @emph{Spanner} objects such as slurs
1881 or beams, the @code{\override} command must be executed at the moment
1882 when the object is created. In this example,
1884 @lilypond[quote,fragment,verbatim]
1885 \override Slur.thickness = #3.0
1887 \override Beam.beam-thickness = #0.6
1892 the slur is fatter but the beam is not. This is because the command for
1893 @code{Beam} comes after the Beam is started, so it has no effect.
1895 Analogous to @code{\unset}, the @code{\revert} command for a context
1896 undoes an @code{\override} command; like with @code{\unset}, it only
1897 affects settings that were made in the same context. In other words, the
1898 @code{\revert} in the next example does not do anything.
1901 \override Voice.Stem.thickness = #4.0
1902 \revert Staff.Stem.thickness
1905 Some tweakable options are called @q{subproperties} and reside inside
1906 properties. To tweak those, use commands of the form
1908 @c leave this as a long long
1910 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1917 \override Stem.details.beamed-lengths = #'(4 4 3)
1923 Internals Reference:
1924 @rinternals{Backend},
1925 @rinternals{All layout objects},
1926 @rinternals{OverrideProperty},
1927 @rinternals{RevertProperty},
1928 @rinternals{PropertySet}.
1931 The back-end is not very strict in type-checking object properties.
1932 Cyclic references in Scheme values for properties can cause hangs
1933 or crashes, or both.
1936 @node The set command
1937 @subsection The @code{@bs{}set} command
1941 @cindex changing properties
1943 Each context has a set of @emph{properties}, variables contained
1944 in that context. Context properties are changed with the @code{\set}
1945 command, which has the following syntax:
1948 \set @var{context}.@var{property} = #@var{value}
1951 @var{value} is a Scheme object, which is why it must be preceded by
1952 the @code{#}@tie{}character.
1954 Contexts properties are usually named in
1955 @code{studlyCaps}. They mostly control the translation from
1956 music to notation, e.g. @code{localAlterations} (for determining
1957 whether to print accidentals), or @code{measurePosition} (for
1958 determining when to print a bar line). Context properties can
1959 change value over time while interpreting a piece of music;
1960 @code{measurePosition} is an obvious example of
1961 this. Context properties are modified with @code{\set}.
1963 For example, multimeasure rests will be combined into a single bar
1964 if the context property @code{skipBars} is set to @code{#t}:
1966 @lilypond[quote,fragment,verbatim]
1968 \set Score.skipBars = ##t
1972 If the @var{context} argument is left out, then the property will be
1973 set in the current bottom context (typically @code{ChordNames},
1974 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1976 @lilypond[quote,fragment,verbatim]
1977 \set Score.autoBeaming = ##f
1980 \set autoBeaming = ##t
1988 The change is applied @q{on-the-fly}, during the music, so that the
1989 setting only affects the second group of eighth notes.
1991 Note that the bottom-most context does not always contain the property
1992 that you wish to change -- for example, attempting to set the
1993 @code{skipBars} property of the default bottom context, in this case
1994 @code{Voice}, will have no effect, because skipBars is a property of
1995 the @code{Score} context.
1997 @lilypond[quote,fragment,verbatim]
2003 Contexts are hierarchical, so if an enclosing context was specified, for
2004 example @code{Staff}, then the change would also apply to all
2005 @code{Voice}s in the current staff.
2009 The @code{\unset} command:
2012 \unset @var{context}.@var{property}
2016 is used to remove the definition of @var{property} from
2017 @var{context}. This command removes
2018 the definition only if it is set in @var{context}.
2019 Properties that have been set in enclosing contexts will
2020 not be altered by an unset in an enclosed context:
2022 @lilypond[quote,fragment,verbatim]
2023 \set Score.autoBeaming = ##t
2027 \unset Score.autoBeaming
2035 Like @code{\set}, the @var{context} argument does not have to be
2036 specified for a bottom context, so the two statements
2039 \set Voice.autoBeaming = ##t
2040 \set autoBeaming = ##t
2044 are equivalent if the current bottom context is @code{Voice}.
2048 Preceding a @code{\set} command by @code{\once} makes the
2049 setting apply to only a single time-step:
2051 @lilypond[quote,fragment,verbatim]
2053 \once \set fontSize = #4.7
2058 A full description of all available context properties is in the
2059 internals reference, see
2061 @rinternals{Tunable context properties}.
2064 Translation @expansion{} Tunable context properties.
2068 Internals Reference:
2069 @rinternals{Tunable context properties}.
2072 @node The override command
2073 @subsection The @code{\override} command
2075 @cindex grob properties
2076 @cindex properties, grob
2079 There is a special type of context property: the grob
2080 description. Grob descriptions are named in @code{StudlyCaps}
2081 (starting with capital letters). They contain the
2082 @q{default settings} for a particular kind of grob as an
2083 association list. See @file{scm/define-grobs.scm}
2084 to see the settings for each grob description. Grob descriptions
2085 are modified with @code{\override}.
2087 The syntax for the @code{\override} command is
2090 \override [@var{context}.]@var{GrobName}.@var{property} = #@var{value}
2093 For example, we can increase the thickness of a note stem by
2094 overriding the @code{thickness} property of the @code{Stem}
2097 @lilypond[quote,fragment,verbatim]
2099 \override Voice.Stem.thickness = #3.0
2103 If no context is specified in an @code{\override}, the bottom
2106 @lilypond[quote,fragment,verbatim]
2107 \override Staff.Stem.thickness = #3.0
2111 \override Stem.thickness = #0.5
2120 Some tweakable options are called @q{subproperties} and reside inside
2121 properties. To tweak those, use commands in the form
2124 \override Stem.details.beamed-lengths = #'(4 4 3)
2127 or to modify the ends of spanners, use a form like these
2130 \override TextSpanner.bound-details.left.text = #"left text"
2131 \override TextSpanner.bound-details.right.text = #"right text"
2135 @cindex reverting overrides
2136 @cindex overrides, reverting
2138 The effects of @code{\override} can be undone by @code{\revert}.
2140 The syntax for the @code{\revert} command is
2143 \revert [@var{context}.]@var{GrobName}.@var{property}
2148 @lilypond[quote,verbatim]
2151 \override Voice.Stem.thickness = #3.0
2153 \revert Voice.Stem.thickness
2158 The effects of @code{\override} and @code{\revert} apply to all
2159 grobs in the affected context from the current time forward:
2161 @lilypond[quote,verbatim]
2165 \override Staff.Stem.thickness = #3.0
2170 \revert Staff.Stem.thickness
2177 @cindex overriding for only one moment
2179 @code{\once} can be used with @code{\override}
2180 to affect only the current time step:
2182 @lilypond[quote,verbatim]
2185 \override Stem.thickness = #3.0
2190 \once \override Stem.thickness = #3.0
2198 Commands which change output generally look like
2201 \override Voice.Stem.thickness = #3.0
2205 To construct this tweak we must determine these bits of information:
2208 @item the context: here @code{Voice}.
2209 @item the layout object: here @code{Stem}.
2210 @item the layout property: here @code{thickness}.
2211 @item a sensible value: here @code{3.0}.
2214 @cindex internal documentation
2215 @cindex finding graphical objects
2216 @cindex graphical object descriptions
2219 @cindex internal documentation
2221 For many properties, regardless of the data type of the property, setting the
2222 property to false (@code{#f}) will result in turning it off, causing
2223 LilyPond to ignore that property entirely. This is particularly useful for
2224 turning off grob properties which may otherwise be causing problems.
2226 We demonstrate how to glean this information from the notation manual
2227 and the program reference.
2231 Internals Reference:
2232 @rinternals{Backend}
2235 @node The tweak command
2236 @subsection The @code{\tweak} command
2241 Changing grob properties
2242 with @code{\override} causes the changes to apply to all of the
2243 given grobs in the context at the moment the change applies.
2244 Sometimes, however, it is desirable to have changes apply to just
2245 one grob, rather than to all grobs in the affected context. This is
2246 accomplished with the @code{\tweak} command, which has the following
2250 \tweak [@var{layout-object}.]@var{grob-property} @var{value}
2253 Specifying @var{layout-object} is optional.
2254 The @code{\tweak} command applies to the music object that immediately
2255 follows @var{value} in the music stream.
2258 In some cases, it is possible to take a short-cut for tuning
2259 graphical objects. For objects that are created directly from
2260 an item in the input file, you can use the @code{\tweak} command.
2263 @lilypond[verbatim,quote]
2269 \tweak duration-log #1
2279 The main use of the @code{\tweak} command is to modify just
2280 one of a number of notation elements which start at the same musical
2281 moment, like the notes of a chord, or tuplet brackets which start
2284 The @code{\tweak} command sets a property in the following object
2285 directly, without requiring the grob name or context to be
2286 specified. For this to work, it is necessary for the @code{\tweak}
2287 command to remain immediately adjacent to the object to which it is
2288 to apply after the input file has been converted to a music stream.
2289 This is often not the case, as many additional elements are inserted
2290 into the music stream implicitly. For example, when a note which is
2291 not part of a chord is processed, LilyPond implicitly inserts a
2292 @code{ChordEvent} event before the note, so separating the tweak
2293 from the note. However, if chord symbols are placed round the
2294 tweak and the note, the @code{\tweak} command comes after the
2295 @code{ChordEvent} in the music stream, so remaining adjacent to the
2296 note, and able to modify it.
2300 @lilypond[verbatim,fragment,quote]
2301 <\tweak color #red c''>4
2307 @lilypond[verbatim,fragment,quote]
2308 \tweak color #red c''4
2313 For an introduction to the syntax and uses of the tweak command
2314 see @rlearning{Tweaking methods}.
2316 When several similar items are placed at the same musical moment,
2317 the @code{\override} command cannot be used to modify just one of
2318 them -- this is where the @code{\tweak} command must be used.
2319 Items which may appear more than once at the same musical moment
2320 include the following:
2322 @c TODO expand to include any further uses of \tweak
2324 @item note heads of notes inside a chord
2325 @item articulation signs on a single note
2326 @item ties between notes in a chord
2327 @item tuplet brackets starting at the same time
2330 @c TODO add examples of these
2332 @cindex chord, modifying one note in
2334 In this example, the color of one note head and the type of another
2335 note head are modified within a single chord:
2337 @lilypond[verbatim,fragment,quote]
2342 \tweak duration-log #1
2347 @code{\tweak} can be used to modify slurs:
2349 @lilypond[verbatim,quote]
2350 \relative { c'-\tweak thickness #5 ( d e f) }
2354 For the @code{\tweak} command to work, it must
2355 remain immediately adjacent to the object to which it is
2356 to apply after the input file has been converted to a music stream.
2357 Tweaking a whole chord does not do anything since its music event
2358 only acts as a container, and all layout objects are created from events
2359 inside of the @code{EventChord}:
2361 @lilypond[verbatim,fragment,quote]
2362 \tweak color #red c''4
2363 \tweak color #red <c'' e''>4
2364 <\tweak color #red c'' e''>4
2367 The simple @code{\tweak} command cannot be used to modify any object
2368 that is not directly created from the input. In particular
2369 it will not affect stems, automatic
2370 beams or accidentals, since these are generated later by
2371 @code{NoteHead} layout objects rather than by music elements in the
2374 Such indirectly created layout objects can be tweaked using the form
2375 of the @code{\tweak} command in which the grob name is specified
2378 @lilypond[fragment,verbatim,quote]
2379 \tweak Stem.color #red
2380 \tweak Beam.color #green c''8 e''
2381 <c'' e'' \tweak Accidental.font-size #-3 ges''>4
2384 @code{\tweak} cannot be used to modify clefs or time
2385 signatures, since these become separated from any preceding
2386 @code{\tweak} command in the input stream by the automatic
2387 insertion of extra elements required to specify the context.
2389 Several @code{\tweak} commands may be placed before a
2390 notational element -- all affect it:
2392 @lilypond[verbatim,fragment,quote]
2394 -\tweak style #'dashed-line
2395 -\tweak dash-fraction #0.2
2396 -\tweak thickness #3
2402 The music stream which is generated from a section of an input file,
2403 including any automatically inserted elements, may be examined,
2404 see @rextend{Displaying music expressions}. This may be helpful in
2405 determining what may be modified by a @code{\tweak} command, or
2406 in determining how to adjust the input to make a @code{\tweak}
2411 @rlearning{Tweaking methods}.
2414 @rextend{Displaying music expressions}.
2418 @cindex tweaking control points
2419 @cindex control points, tweaking
2421 The @code{\tweak} command cannot be used to modify the control
2422 points of just one of several ties in a chord, other than the first
2423 one encountered in the input file.
2425 @node set versus override
2426 @subsection @code{\set} vs. @code{\override}
2428 @c TODO Should't a bunch of that be explained earlier?
2432 Both @code{\set} and @code{\override} manipulate properties
2433 associated with contexts. In either case, properties heed the
2434 hierarchy of contexts: properties not set in a context itself show
2435 the values of the respective parent context.
2437 Values and lifetime of context properties are dynamic and only
2438 available when music is being interpreted, @q{iterated}. At the
2439 time of context creation, properties are initialized from the
2440 corresponding context definition and possible context
2441 modifications. Afterwards, changes are achieved with
2442 property-setting commands in the music itself.
2444 Now grob definitions are a special category of context properties.
2445 Since their structure, bookkeeping and use is different from
2446 ordinary context properties, they are accessed with a different
2447 set of commands, and treated separately in the documentation.
2449 As opposed to plain context properties, grob definitions are
2450 subdivided into grob properties. A @qq{grob} (graphical object)
2451 is usually created by an engraver at the time of interpreting a
2452 music expression and receives its initial properties from the
2453 current grob definition of the engraver's context. The engraver
2454 (or other @q{backend} parts of LilyPond) may subsequently add or
2455 change properties to the grob, but that does not affect the
2456 context's grob definition.
2458 What we call @q{grob properties} in the context of user-level
2459 tweaking are actually the properties of a context's grob
2460 definition. In contrast to ordinary context properties, grob
2461 definitions have the bookkeeping required to keep track of its
2462 parts, the individual grob properties (and even subproperties of
2463 them) separately so that it is possible to define those parts in
2464 different contexts and have the overall grob definition at the
2465 time of grob creation be assembled from pieces provided in
2466 different contexts among the current context and its parents.
2468 Grob definitions are manipulated using @code{\override} and
2469 @code{\revert} and have a name starting with a capital letter
2470 (like @samp{NoteHead}) whereas ordinary context properties are
2471 manipulated using @code{\set} and @code{\unset} and are named
2472 starting with a lowercase letter.
2474 @cindex tweak, relation to @code{\override}
2476 @funindex \overrideProperty
2477 The special commands @code{\tweak} and @code{\overrideProperty}
2478 change grob properties bypassing context properties completely.
2479 Instead they catch grobs as they are being created and then
2480 directly set properties on them when they originate from a tweaked
2481 music event or are of a particular kind, respectively.
2483 @node Modifying alists
2484 @subsection Modifying alists
2486 Some user-configurable properties are internally represented as
2487 @emph{alists} (association lists), which store pairs of
2488 @emph{keys} and @emph{values}. The structure of an alist is:
2491 '((@var{key1} . @var{value1})
2492 (@var{key2} . @var{value2})
2493 (@var{key3} . @var{value3})
2497 If an alist is a grob property or @code{\paper} variable, its keys
2498 can be modified individually without affecting other keys.
2500 For example, to reduce the space between adjacent staves in a
2501 staff-group, use the @code{staff-staff-spacing} property of the
2502 @code{StaffGrouper} grob. The property is an alist with four
2503 keys: @code{basic-distance}, @code{minimum-distance},
2504 @code{padding}, and @code{stretchability}. The standard settings
2505 for this property are listed in the @qq{Backend} section of the
2506 Internals Reference (see @rinternals{StaffGrouper}):
2509 '((basic-distance . 9)
2510 (minimum-distance . 7)
2512 (stretchability . 5))
2515 One way to bring the staves closer together is by reducing the
2516 value of the @code{basic-distance} key (@code{9}) to match the
2517 value of @code{minimum-distance} (@code{7}). To modify a single
2518 key individually, use a @emph{nested declaration}:
2520 @lilypond[quote,verbatim]
2521 % default space between staves
2523 \new Staff { \clef treble c''1 }
2524 \new Staff { \clef bass c1 }
2527 % reduced space between staves
2528 \new PianoStaff \with {
2529 % this is the nested declaration
2530 \override StaffGrouper.staff-staff-spacing.basic-distance = #7
2532 \new Staff { \clef treble c''1 }
2533 \new Staff { \clef bass c1 }
2537 Using a nested declaration will update the specified key (such as
2538 @code{basic-distance} in the above example) without altering any
2539 other keys already set for the same property.
2541 Now suppose we want the staves to be as close as possible without
2542 overlapping. The simplest way to do this is to set all four alist
2543 keys to zero. However, it is not necessary to enter four nested
2544 declarations, one for each key. Instead, the property can be
2545 completely re-defined with one declaration, as an alist:
2547 @lilypond[quote,verbatim]
2548 \new PianoStaff \with {
2549 \override StaffGrouper.staff-staff-spacing =
2550 #'((basic-distance . 0)
2551 (minimum-distance . 0)
2553 (stretchability . 0))
2555 \new Staff { \clef treble c''1 }
2556 \new Staff { \clef bass c1 }
2560 Note that any keys not explicitly listed in the alist definition
2561 will be reset to their @emph{default-when-unset} values. In the
2562 case of @code{staff-staff-spacing}, any unset key-values would be
2563 reset to zero (except @code{stretchability}, which takes the value
2564 of @code{basic-distance} when unset). Thus the following two
2565 declarations are equivalent:
2568 \override StaffGrouper.staff-staff-spacing =
2569 #'((basic-distance . 7))
2571 \override StaffGrouper.staff-staff-spacing =
2572 #'((basic-distance . 7)
2573 (minimum-distance . 0)
2575 (stretchability . 7))
2578 One (possibly unintended) consequence of this is the removal of
2579 any standard settings that are set in an initialization file and
2580 loaded each time an input file is compiled. In the above example,
2581 the standard settings for @code{padding} and
2582 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2583 are reset to their default-when-unset values (zero for both keys).
2584 Defining a property or variable as an alist (of any size) will
2585 always reset all unset key-values to their default-when-unset
2586 values. Unless this is the intended result, it is safer to update
2587 key-values individually with a nested declaration.
2589 @warning{Nested declarations will not work for context property
2590 alists (such as @code{beamExceptions}, @code{keyAlterations},
2591 @code{timeSignatureSettings}, etc.). These properties can only be
2592 modified by completely re-defining them as alists.}
2595 @node Useful concepts and properties
2596 @section Useful concepts and properties
2601 * Direction and placement::
2602 * Distances and measurements::
2604 * Staff symbol properties::
2606 * Visibility of objects::
2608 * Rotating objects::
2612 @subsection Input modes
2614 The way in which the notation contained within an input file is
2615 interpreted is determined by the current input mode.
2617 @subsubsubheading Chord mode
2619 This is activated with the @code{\chordmode} command, and causes
2620 input to be interpreted with the syntax of chord notation, see
2621 @ref{Chord notation}. Chords are rendered as notes on a staff.
2623 Chord mode is also activated with the @code{\chords} command.
2624 This also creates a new @code{ChordNames} context and
2625 causes the following input to be interpreted with the syntax of
2626 chord notation and rendered as chord names in the @code{ChordNames}
2627 context, see @ref{Printing chord names}.
2629 @subsubsubheading Drum mode
2631 This is activated with the @code{\drummode} command, and causes
2632 input to be interpreted with the syntax of drum notation, see
2633 @ref{Basic percussion notation}.
2635 Drum mode is also activated with the @code{\drums} command.
2636 This also creates a new @code{DrumStaff} context and causes the
2637 following input to be interpreted with the syntax of drum notation
2638 and rendered as drum symbols on a drum staff, see
2639 @ref{Basic percussion notation}.
2641 @subsubsubheading Figure mode
2643 This is activated with the @code{\figuremode} command, and causes
2644 input to be interpreted with the syntax of figured bass, see
2645 @ref{Entering figured bass}.
2647 Figure mode is also activated with the @code{\figures} command.
2648 This also creates a new @code{FiguredBass} context and causes the
2649 following input to be interpreted with the figured bass syntax
2650 and rendered as figured bass symbols in the @code{FiguredBass}
2651 context, see @ref{Introduction to figured bass}.
2653 @subsubsubheading Fret and tab modes
2655 There are no special input modes for entering fret and tab symbols.
2657 To create tab diagrams, enter notes or chords in note mode and
2658 render them in a @code{TabStaff} context, see
2659 @ref{Default tablatures}.
2661 To create fret diagrams above a staff, you have two choices.
2662 You can either use the @code{FretBoards} context (see
2663 @ref{Automatic fret diagrams} or you can enter them as a markup
2664 above the notes using the @code{\fret-diagram} command (see
2665 @ref{Fret diagram markups}).
2667 @subsubsubheading Lyrics mode
2669 This is activated with the @code{\lyricmode} command, and causes
2670 input to be interpreted as lyric syllables with optional durations
2671 and associated lyric modifiers, see @ref{Vocal music}.
2673 Lyric mode is also activated with the @code{\addlyrics} command.
2674 This also creates a new @code{Lyrics} context and an implicit
2675 @code{\lyricsto} command which associates the following lyrics
2676 with the preceding music.
2678 @subsubsubheading Markup mode
2680 This is activated with the @code{\markup} command, and causes
2681 input to be interpreted with the syntax of markup, see
2682 @ref{Text markup commands}.
2684 @subsubsubheading Note mode
2686 This is the default mode or it may be activated with the
2687 @code{\notemode} command. Input is interpreted as pitches,
2688 durations, markup, etc and typeset as musical notation on a staff.
2690 It is not normally necessary to specify note mode explicitly, but
2691 it may be useful to do so in certain situations, for example if you
2692 are in lyric mode, chord mode or any other mode and want to insert
2693 something that only can be done with note mode syntax.
2696 @node Direction and placement
2697 @subsection Direction and placement
2699 In typesetting music the direction and placement of many items is
2700 a matter of choice. For example, the stems of notes can
2701 be directed up or down; lyrics, dynamics, and other expressive
2702 marks may be placed above or below the staff; text may be aligned
2703 left, right or center; etc. Most of these choices may be left to
2704 be determined automatically by LilyPond, but in some cases it may
2705 be desirable to force a particular direction or placement.
2708 * Articulation direction indicators::
2709 * The direction property::
2712 @node Articulation direction indicators
2713 @unnumberedsubsubsec Articulation direction indicators
2715 By default some directions are always up or always down (e.g.
2716 dynamics or fermata), while other things can alternate between
2717 up or down based on the stem direction (like slurs or accents).
2719 @c TODO Add table showing these
2721 The default action may be overridden by prefixing the articulation
2722 by a @emph{direction indicator}. Three direction indicators are
2723 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2724 and @code{-} (meaning @qq{use default direction}). The direction
2725 indicator can usually be omitted, in which case @code{-} is assumed,
2726 but a direction indicator is @strong{always} required before
2729 @item @code{\tweak} commands
2730 @item @code{\markup} commands
2731 @item @code{\tag} commands
2732 @item string markups, e.g. -"string"
2733 @item fingering instructions, e.g. @w{@code{-1}}
2734 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2737 Direction indicators affect only the next note:
2739 @lilypond[verbatim,quote]
2748 @node The direction property
2749 @unnumberedsubsubsec The direction property
2751 The position or direction of many layout objects is controlled by the
2752 @code{direction} property.
2754 The value of the @code{direction} property may be set to @code{1},
2755 meaning @qq{up} or @qq{above}, or to @w{@code{-1}}, meaning @qq{down} or
2756 @qq{below}. The symbols @code{UP} and @code{DOWN} may be used instead
2757 of @code{1} and @w{@code{-1}} respectively. The default direction may
2758 be specified by setting @code{direction} to @code{0} or @code{CENTER}.
2759 Alternatively, in many cases predefined commands exist to specify the
2760 direction. These are of the form
2763 @code{\xxxUp}, @code{\xxxDown} or @code{\xxxNeutral}
2767 where @code{\xxxNeutral} means @qq{use the default} direction.
2768 See @rlearning{Within-staff objects}.
2770 In a few cases, arpeggio for example, the value of the @code{direction}
2771 property can specify whether the object is to be placed to the right or
2772 left of the parent. In this case @w{@code{-1}} or @code{LEFT} means
2773 @qq{to the left} and @code{1} or @code{RIGHT} means @qq{to the right}.
2774 @code{0} or @code{CENTER} means @qq{use the default} direction.
2777 These all have side-axis set to #X
2778 AmbitusAccidental - direction has no effect
2780 StanzaNumber - not tried
2781 TrillPitchAccidental - not tried
2782 TrillPitchGroup - not tried
2785 These indications affect all notes until they are canceled.
2787 @lilypond[verbatim,quote]
2798 In polyphonic music, it is generally better to specify an explicit
2799 @code{voice} than change an object's direction. For more information.
2800 See @ref{Multiple voices}.
2804 @rlearning{Within-staff objects}.
2807 @ref{Multiple voices}.
2810 @node Distances and measurements
2811 @subsection Distances and measurements
2813 @cindex distances, absolute
2814 @cindex distances, scaled
2821 Distances in LilyPond are of two types: absolute and scaled.
2823 Absolute distances are used for specifying margins, indents, and
2824 other page layout details, and are by default specified in
2825 millimeters. Distances may be specified in other units by
2826 following the quantity by @code{\mm}, @code{\cm},
2827 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2828 an inch). Page layout distances can also be specified in scalable
2829 units (see the following paragraph) by appending
2830 @code{\staff-space} to the quantity. Page layout is described in
2831 detail in @ref{Page layout}.
2833 Scaled distances are always specified in units of the staff-space
2834 or, rarely, the half staff-space. The staff-space is the distance
2835 between two adjacent staff lines. The default value can be changed
2836 globally by setting the global staff size, or it can be overridden
2837 locally by changing the @code{staff-space} property of
2838 @code{StaffSymbol}. Scaled distances automatically scale with any
2839 change to the either the global staff size or the
2840 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2841 automatically only with changes to the global staff size.
2842 The global staff size thus enables the overall size of a rendered
2843 score to be easily varied. For the methods of setting the global
2844 staff size see @ref{Setting the staff size}.
2848 If just a section of a score needs to be rendered to a different
2849 scale, for example an ossia section or a footnote, the global staff
2850 size cannot simply be changed as this would affect the entire score.
2851 In such cases the change in size is made by overriding both the
2852 @code{staff-space} property of @code{StaffSymbol} and the size of
2853 the fonts. A Scheme function, @code{magstep}, is available to
2854 convert from a font size change to the equivalent change in
2855 @code{staff-space}. For an explanation and an example of its use,
2856 see @rlearning{Length and thickness of objects}.
2860 @rlearning{Length and thickness of objects}.
2864 @ref{Setting the staff size}.
2868 @subsection Dimensions
2871 @cindex bounding box
2873 The dimensions of a graphical object specify the positions of the left
2874 and right edges and the bottom and top edges of the objects' bounding
2875 box as distances from the objects' reference point in units of
2876 staff-spaces. These positions are usually coded as two Scheme pairs.
2877 For example, the text markup command @code{\with-dimensions} takes
2878 three arguments, the first two of which are a Scheme pair giving the
2879 left and right edge positions and a Scheme pair giving the bottom and
2883 \with-dimensions #'(-5 . 10) #'(-3 . 15) @var{arg}
2886 This specifies a bounding box for @var{arg} with its left edge at -5,
2887 its right edge at 10, its bottom edge at -3 and its top edge at 15,
2888 all measured from the objects' reference point in units of
2893 @ref{Distances and measurements}.
2896 @node Staff symbol properties
2897 @subsection Staff symbol properties
2899 @cindex adjusting staff symbol
2900 @cindex drawing staff symbol
2901 @cindex staff symbol, setting of
2903 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2904 @c Need to think of uses for these properties. Eg 'line-positions
2905 @c is used in a snippet to thicken centre line.
2906 @c If retained, add @ref to here in 1.6.2 -td
2908 The vertical position of staff lines and the number of staff lines
2909 can be defined at the same time. As the following example shows,
2910 note positions are not influenced by the staff line positions.
2912 @warning{The @code{'line-positions} property overrides the
2913 @code{'line-count} property. The number of staff lines is
2914 implicitly defined by the number of elements in the list of values
2915 for @code{'line-positions}.}
2917 @lilypond[verbatim,quote]
2919 \override StaffSymbol.line-positions = #'(7 3 0 -4 -6 -7)
2921 \relative { a4 e' f b | d1 }
2924 The width of a staff can be modified. The units are staff
2925 spaces. The spacing of objects inside the staff is not affected by
2928 @lilypond[verbatim,quote]
2930 \override StaffSymbol.width = #23
2932 \relative { a4 e' f b | d1 }
2937 @subsection Spanners
2939 Many objects of musical notation extend over several notes or even
2940 several bars. Examples are slurs, beams, tuplet brackets, volta
2941 repeat brackets, crescendi, trills, and glissandi. Such objects
2942 are collectively called @qq{spanners}, and have special properties to control
2943 their appearance and behaviour. Some of these properties are common
2944 to all spanners; others are restricted to a sub-set of the spanners.
2946 All spanners support the @code{spanner-interface}. A few, essentially
2947 those that draw a straight line between the two objects, support in
2948 addition the @code{line-spanner-interface}.
2951 * Using the spanner-interface::
2952 * Using the line-spanner-interface::
2955 @node Using the spanner-interface
2956 @unnumberedsubsubsec Using the @code{spanner-interface}
2958 This interface provides two properties that apply to several spanners.
2960 @subsubsubheading The @code{minimum-length} property
2962 The minimum length of the spanner is specified by the
2963 @code{minimum-length} property. Increasing this usually has the
2964 necessary effect of increasing the spacing of the notes between the
2965 two end points. However, this override has no effect on
2966 many spanners, as their length is determined by other considerations.
2967 A few examples where it is effective are shown below.
2977 Works as long as callback is made:
2981 Works not at all for:
2990 @lilypond[verbatim,quote,fragment]
2993 % increase the length of the tie
2994 -\tweak minimum-length #5
2998 @lilypond[verbatim,quote]
2999 \relative \compressMMRests {
3002 % increase the length of the rest bar
3003 \once \override MultiMeasureRest.minimum-length = #20
3009 @lilypond[verbatim,quote]
3012 % increase the length of the hairpin
3013 \override Hairpin.minimum-length = #20
3018 This override can also be used to increase the length of slurs and
3021 @lilypond[verbatim,quote]
3025 -\tweak minimum-length #5
3030 -\tweak minimum-length #5
3035 For some layout objects, the @code{minimum-length} property becomes
3036 effective only if the @code{set-spacing-rods} procedure is called
3037 explicitly. To do this, the @code{springs-and-rods} property should
3038 be set to @code{ly:spanner::set-spacing-rods}. For example,
3039 the minimum length of a glissando has no effect unless the
3040 @code{springs-and-rods} property is set:
3042 @lilypond[verbatim,fragment,quote]
3046 % not effective alone
3047 \once \override Glissando.minimum-length = #20
3050 % effective only when both overrides are present
3051 \once \override Glissando.minimum-length = #20
3052 \once \override Glissando.springs-and-rods = #ly:spanner::set-spacing-rods
3056 The same is true of the @code{Beam} object:
3058 @lilypond[verbatim,fragment,quote]
3059 % not effective alone
3060 \once \override Beam.minimum-length = #20
3063 % effective only when both overrides are present
3064 \once \override Beam.minimum-length = #20
3065 \once \override Beam.springs-and-rods = #ly:spanner::set-spacing-rods
3069 @subsubsubheading The @code{to-barline} property
3071 The second useful property of the @code{spanner-interface} is
3072 @code{to-barline}. By default this is true, causing hairpins and
3073 other spanners which are terminated on the first note of a measure to
3074 end instead on the immediately preceding bar line. If set to false,
3075 the spanner will extend beyond the bar line and end on the note
3078 @lilypond[verbatim,quote]
3080 a' \< a a a a \! a a a \break
3081 \override Hairpin.to-barline = ##f
3082 a \< a a a a \! a a a
3086 This property is not effective for all spanners. For example,
3087 setting it to @code{#t} has no effect on slurs or phrasing slurs
3088 or on other spanners for which terminating on the bar line would
3091 @node Using the line-spanner-interface
3092 @unnumberedsubsubsec Using the @code{line-spanner-interface}
3094 Objects which support the @code{line-spanner-interface} include
3097 @item @code{DynamicTextSpanner}
3098 @item @code{Glissando}
3099 @item @code{TextSpanner}
3100 @item @code{TrillSpanner}
3101 @item @code{VoiceFollower}
3104 The routine responsible for drawing the stencils for these spanners is
3105 @code{ly:line-spanner::print}. This routine determines the
3106 exact location of the two end points and draws a line
3107 between them, in the style requested. The locations of the two
3108 end points of the spanner are computed on-the-fly, but it is
3109 possible to override their Y-coordinates. The
3110 properties which need to be specified are nested
3111 two levels down within the property hierarchy, but the syntax of
3112 the @code{\override} command is quite simple:
3114 @lilypond[quote,fragment,verbatim]
3116 \once \override Glissando.bound-details.left.Y = #3
3117 \once \override Glissando.bound-details.right.Y = #-2
3121 The units for the @code{Y} property are @code{staff-space}s,
3122 with the center line of the staff being the zero point.
3123 For the glissando, this is the value for @code{Y} at the
3124 X-coordinate corresponding to the center point of each note head,
3125 if the line is imagined to be extended to there.
3127 If @code{Y} is not set, the value is computed from the vertical
3128 position of the corresponding attachment point of the spanner.
3130 In case of a line break, the values for the end points are
3131 specified by the @code{left-broken} and @code{right-broken}
3132 sub-lists of @code{bound-details}. For example:
3134 @lilypond[ragged-right,fragment,verbatim,quote]
3135 \override Glissando.breakable = ##t
3136 \override Glissando.bound-details.right-broken.Y = #-3
3137 c''1 \glissando \break
3142 A number of further properties of the @code{left} and
3143 @code{right} sub-lists of the @code{bound-details} property
3144 may be modified in the same way as @code{Y}:
3148 This sets the Y-coordinate of the end point, in @code{staff-space}s
3149 offset from the staff center line. By default, it is the center of
3150 the bound object, so a glissando points to the vertical center of
3153 For horizontal spanners, such as text spanners and trill spanners,
3154 it is hardcoded to 0.
3157 This determines where the line starts and ends in the X-direction,
3158 relative to the bound object. So, a value of @w{@code{-1}} (or
3159 @code{LEFT}) makes the line start/end at the left side of the note
3160 head it is attached to.
3163 This is the absolute X-coordinate of the end point. It is usually
3164 computed on the fly, and overriding it has little useful effect.
3167 Line spanners may have symbols at the beginning or end, which is
3168 contained in this sub-property. This is for internal use; it is
3169 recommended that @code{text} be used instead.
3172 This is a markup that is evaluated to yield the stencil. It is used
3173 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
3175 @lilypond[quote,ragged-right,fragment,verbatim]
3176 \override TextSpanner.bound-details.left.text
3177 = \markup { \small \bold Slower }
3178 \relative { c''2\startTextSpan b c a\stopTextSpan }
3181 @item stencil-align-dir-y
3182 @item stencil-offset
3183 Without setting one of these, the stencil is simply put at the
3184 end-point, centered on the line, as defined by the @code{X} and
3185 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
3186 or @code{stencil-offset} will move the symbol at the edge vertically
3187 relative to the end point of the line:
3189 @lilypond[quote,fragment,verbatim]
3190 \override TextSpanner.bound-details.left.stencil-align-dir-y = #-2
3191 \override TextSpanner.bound-details.right.stencil-align-dir-y = #UP
3193 \override TextSpanner.bound-details.left.text = #"ggg"
3194 \override TextSpanner.bound-details.right.text = #"hhh"
3196 \relative { c'4^\startTextSpan c c c \stopTextSpan }
3199 Note that negative values move the text @emph{up}, contrary to the
3200 effect that might be expected, as a value of @w{@code{-1}} or
3201 @code{DOWN} means align the @emph{bottom} edge of the text with
3202 the spanner line. A value of @code{1} or @code{UP} aligns
3203 the top edge of the text with the spanner line.
3206 Setting this sub-property to @code{#t} produces an arrowhead at the
3210 This sub-property controls the space between the specified
3211 end point of the line and the actual end. Without padding, a
3212 glissando would start and end in the center of each note head.
3216 The music function @code{\endSpanners} terminates the spanner
3217 which starts on the immediately following note prematurely. It
3218 is terminated after exactly one note, or at the following bar line
3219 if @code{to-barline} is true and a bar line occurs before the next
3222 @lilypond[verbatim,quote,ragged-right]
3225 c2 \startTextSpan c2 c2
3231 When using @code{\endSpanners} it is not necessary to close
3232 \startTextSpan with \stopTextSpan, nor is it necessary to close
3233 hairpins with @code{\!}.
3236 Internals Reference:
3237 @rinternals{TextSpanner},
3238 @rinternals{Glissando},
3239 @rinternals{VoiceFollower},
3240 @rinternals{TrillSpanner},
3241 @rinternals{line-spanner-interface}.
3244 @node Visibility of objects
3245 @subsection Visibility of objects
3247 @cindex objects, visibility of
3248 @cindex grobs, visibility of
3249 @cindex visibility of objects
3251 There are four main ways in which the visibility of layout objects
3252 can be controlled: their stencil can be removed, they can be made
3253 transparent, they can be colored white, or their
3254 @code{break-visibility} property can be overridden. The first
3255 three apply to all layout objects; the last to just a few -- the
3256 @emph{breakable} objects. The Learning Manual introduces these
3257 four techniques, see @rlearning{Visibility and color of objects}.
3259 There are also a few other techniques which are specific to
3260 certain layout objects. These are covered under Special
3264 * Removing the stencil::
3265 * Making objects transparent::
3266 * Painting objects white::
3267 * Using break-visibility::
3268 * Special considerations::
3272 @node Removing the stencil
3273 @unnumberedsubsubsec Removing the stencil
3275 @cindex stencil, removing
3278 Every layout object has a stencil property. By default this is set
3279 to the specific function which draws that object. If this property
3280 is overridden to @code{#f} no function will be called and the object
3281 will not be drawn. The default action can be recovered with
3284 @lilypond[quote,fragment,verbatim]
3286 \override Score.BarLine.stencil = ##f
3288 \revert Score.BarLine.stencil
3292 This rather common operation has a shortcut @code{\omit}:
3294 @lilypond[quote,fragment,verbatim]
3298 \undo \omit Score.BarLine
3302 @node Making objects transparent
3303 @unnumberedsubsubsec Making objects transparent
3305 @cindex transparent, making objects
3308 Every layout object has a transparent property which by default is
3309 set to @code{#f}. If set to @code{#t} the object still occupies
3310 space but is made invisible.
3312 @lilypond[quote,fragment,verbatim]
3314 \once \override NoteHead.transparent = ##t
3318 This rather common operation has a shortcut @code{\hide}:
3320 @lilypond[quote,fragment,verbatim]
3322 \once \hide NoteHead
3326 @node Painting objects white
3327 @unnumberedsubsubsec Painting objects white
3329 @cindex objects, coloring
3330 @cindex coloring objects
3332 @cindex printing order
3333 @cindex overwriting objects
3334 @cindex objects, overwriting
3335 @cindex grobs, overwriting
3337 Every layout object has a color property which by default is set
3338 to @code{black}. If this is overridden to @code{white} the object
3339 will be indistinguishable from the white background. However,
3340 if the object crosses other objects the color of the crossing
3341 points will be determined by the order in which they are drawn,
3342 and this may leave a ghostly image of the white object, as shown
3345 @lilypond[quote,fragment,verbatim]
3346 \override Staff.Clef.color = #white
3350 This may be avoided by changing the order of printing the objects.
3351 All layout objects have a @code{layer} property which should be set
3352 to an integer. Objects with the lowest value of @code{layer} are
3353 drawn first, then objects with progressively higher values are drawn,
3354 so objects with higher values overwrite objects with lower values.
3355 By default most objects are assigned a @code{layer} value of
3356 @code{1}, although a few objects, including @code{StaffSymbol} and
3357 @code{BarLine}, are assigned a value of @code{0}. The order of
3358 printing objects with the same value of @code{layer} is indeterminate.
3360 In the example above the white clef, with a default @code{layer}
3361 value of @code{1}, is drawn after the staff lines (default
3362 @code{layer} value @code{0}), so overwriting them. To change this,
3363 the @code{Clef} object must be given in a lower value of
3364 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
3366 @lilypond[quote,fragment,verbatim]
3367 \override Staff.Clef.color = #white
3368 \override Staff.Clef.layer = #-1
3372 @node Using break-visibility
3373 @unnumberedsubsubsec Using break-visibility
3375 @c TODO Add making other objects breakable
3377 @cindex break-visibility
3379 Most layout objects are printed only once, but some like
3380 bar lines, clefs, time signatures and key signatures, may need
3381 to be printed twice when a line break occurs -- once at the end
3382 of the line and again at the start of the next line. Such
3383 objects are called @emph{breakable}, and have a property, the
3384 @code{break-visibility} property to control their visibility
3385 at the three positions in which they may appear -- at the
3386 start of a line, within a line if they are changed, and at the
3387 end of a line if a change takes place there.
3389 For example, the time signature
3390 by default will be printed at the start of the first line, but
3391 nowhere else unless it changes, when it will be printed at the
3392 point at which the change occurs. If this change occurs at the
3393 end of a line the new time signature will be printed at the start
3394 of the next line and a cautionary time signature will be printed
3395 at the end of the previous line as well.
3397 This behaviour is controlled by the @code{break-visibility}
3398 property, which is explained in
3399 @c Leave this ref on a newline - formats incorrectly otherwise -td
3400 @rlearning{Visibility and color of objects}. This property takes
3401 a vector of three booleans which, in order, determine whether the
3402 object is printed at the end of, within the body of, or at the
3403 beginning of a line. Or to be more precise, before a line break,
3404 where there is no line break, or after a line break.
3406 Alternatively, these eight combinations may be specified
3407 by pre-defined functions, defined in @file{scm/output-lib.scm},
3408 where the last three columns indicate whether the layout objects
3409 will be visible in the positions shown at the head of the columns:
3411 @multitable {@code{begin-of-line-invisible}} {@code{#(#t #t #t)}} {Before} {At no} {After}
3412 @headitem Function @tab Vector @tab Before @tab At no @tab After
3413 @headitem form @tab form @tab break @tab break @tab break
3415 @item @code{all-visible} @tab @code{#(#t #t #t)} @tab yes @tab yes @tab yes
3416 @item @code{begin-of-line-visible} @tab @code{#(#f #f #t)} @tab no @tab no @tab yes
3417 @item @code{center-visible} @tab @code{#(#f #t #f)} @tab no @tab yes @tab no
3418 @item @code{end-of-line-visible} @tab @code{#(#t #f #f)} @tab yes @tab no @tab no
3419 @item @code{begin-of-line-invisible} @tab @code{#(#t #t #f)} @tab yes @tab yes @tab no
3420 @item @code{center-invisible} @tab @code{#(#t #f #t)} @tab yes @tab no @tab yes
3421 @item @code{end-of-line-invisible} @tab @code{#(#f #t #t)} @tab no @tab yes @tab yes
3422 @item @code{all-invisible} @tab @code{#(#f #f #f)} @tab no @tab no @tab no
3425 The default settings of @code{break-visibility} depend on the
3426 layout object. The following table shows all the layout objects
3427 of interest which are affected by @code{break-visibility} and the
3428 default setting of this property:
3430 @multitable @columnfractions .3 .3 .4
3432 @headitem Layout object @tab Usual context @tab Default setting
3434 @c omit Ambitus as it appears not to be affected by break-visibility -td
3435 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
3436 @item @code{BarLine} @tab @code{Score} @tab calculated
3437 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
3438 @c omit the following item until it can be explained -td
3439 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
3440 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3441 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
3442 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
3443 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3444 @item @code{KeyCancellation} @tab @code{Staff} @tab @code{begin-of-line-invisible}
3445 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
3446 @c omit LeftEdge until it can be explained -td
3447 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
3448 @item @code{ClefModifier} @tab @code{Staff} @tab @code{begin-of-line-visible}
3449 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
3450 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
3454 The example below shows the use of the vector form to control the
3455 visibility of bar lines:
3457 @lilypond[quote,verbatim,ragged-right]
3461 % Remove bar line at the end of the current line
3462 \once \override Score.BarLine.break-visibility = ##(#f #t #t)
3469 Although all three components of the vector used to override
3470 @code{break-visibility} must be present, not all of them are
3471 effective with every layout object, and some combinations may
3472 even give errors. The following limitations apply:
3475 @item Bar lines cannot be printed at start of line.
3476 @item A bar number cannot be printed at the start of the first
3477 line unless it is set to be different from 1.
3478 @item Clef -- see below
3479 @item Double percent repeats are either all printed or all
3480 suppressed. Use begin-of line-invisible to print and
3481 all-invisible to suppress.
3482 @item Key signature -- see below
3483 @item ClefModifier -- see below
3486 @node Special considerations
3487 @unnumberedsubsubsec Special considerations
3489 @subsubsubheading Visibility following explicit changes
3491 @cindex key signature, visibility following explicit change
3492 @cindex explicitKeySignatureVisibility
3493 @cindex clef, visibility following explicit change
3494 @cindex explicitClefVisibility
3496 The @code{break-visibility} property controls the visibility of
3497 key signatures and changes of clef only at the start of lines,
3498 i.e. after a break. It has no effect on the visibility of the
3499 key signature or clef following an explicit key change or an
3500 explicit clef change within or at the end of a line. In the
3501 following example the key signature following the explicit change
3502 to B-flat major is still visible, even though @code{all-invisible}
3505 @lilypond[quote,verbatim,ragged-right]
3509 % Try to remove all key signatures
3510 \override Staff.KeySignature.break-visibility = #all-invisible
3519 The visibility of such explicit key signature and clef changes is
3520 controlled by the @code{explicitKeySignatureVisibility} and
3521 @code{explicitClefVisibility} properties. These are the equivalent
3522 of the @code{break-visibility} property and both take a vector of
3523 three booleans or the predefined functions listed above, exactly like
3524 @code{break-visibility}. Both are properties of the Staff context,
3525 not the layout objects themselves, and so they are set using the
3526 @code{\set} command. Both are set by default to @code{all-visible}.
3527 These properties control only the visibility of key signatures and
3528 clefs resulting from explicit changes and do not affect key
3529 signatures and clefs at the beginning of lines;
3530 @code{break-visibility} must still be overridden in the appropriate
3531 object to remove these.
3533 @lilypond[quote,verbatim,ragged-right]
3537 \set Staff.explicitKeySignatureVisibility = #all-invisible
3538 \override Staff.KeySignature.break-visibility = #all-invisible
3546 @subsubsubheading Visibility of cancelling accidentals
3548 To remove the cancelling accidentals printed at an explicit key
3549 change, set the Staff context property @code{printKeyCancellation}
3552 @lilypond[quote,verbatim,ragged-right]
3556 \set Staff.explicitKeySignatureVisibility = #all-invisible
3557 \set Staff.printKeyCancellation = ##f
3558 \override Staff.KeySignature.break-visibility = #all-invisible
3566 With these overrides only the accidentals before the notes remain
3567 to indicate the change of key.
3569 Note that when changing the key to C@tie{}major or A@tie{}minor
3570 the cancelling accidentals would be the @emph{only} indication of
3571 the key change. In this case setting @code{printKeyCancellation} to
3572 @code{#f} has no effect:
3574 @lilypond[quote,verbatim,ragged-right]
3578 \set Staff.explicitKeySignatureVisibility = #all-invisible
3579 \set Staff.printKeyCancellation = ##f
3587 To suppress the cancelling accidentals even when the key is
3588 changed to C@tie{}major or A@tie{}minor, override
3589 the visibility of the @code{KeyCancellation} grob instead:
3591 @lilypond[quote,verbatim,ragged-right]
3595 \set Staff.explicitKeySignatureVisibility = #all-invisible
3596 \override Staff.KeyCancellation.break-visibility = #all-invisible
3604 @c TODO Add visibility of cautionary accidentals before notes
3606 @subsubsubheading Automatic bars
3608 @cindex automaticBars
3609 @cindex bar lines, suppressing
3611 As a special case, the printing of bar lines can also be turned off
3612 by setting the @code{automaticBars} property in the Score context.
3613 If set to @code{#f}, bar lines will not be printed automatically;
3614 they must be explicitly created with a @code{\bar} command. Unlike
3615 the @code{\cadenzaOn} predefined command, measures are still counted.
3616 Bar generation will resume according to that count if this property
3617 is later set to @code{#t}. When set to @code{#f}, line breaks can
3618 occur only at explicit @code{\bar} commands.
3622 @subsubsubheading Transposed clefs
3624 @cindex transposed clefs, visibility of
3625 @cindex visibility of transposed clefs
3626 @cindex clefs, visibility of transposition
3628 The small transposition symbol on transposed clefs is produced by the
3629 @code{ClefModifier} layout object. Its visibility is automatically
3630 inherited from the @code{Clef} object, so it is not necessary to apply
3631 any required @code{break-visibility} overrides to the @code{ClefModifier}
3632 layout objects to suppress transposition symbols for invisible clefs.
3634 For explicit clef changes, the @code{explicitClefVisibility}
3635 property controls both the clef symbol and any transposition symbol
3640 @rlearning{Visibility and color of objects}.
3644 @subsection Line styles
3646 Some performance indications, e.g., @i{rallentando} and
3647 @i{accelerando} and @i{trills} are written as text and are
3648 extended over many measures with lines, sometimes dotted or wavy.
3650 These all use the same routines as the glissando for drawing the
3651 texts and the lines, and tuning their behavior is therefore also
3652 done in the same way. It is done with a spanner, and the routine
3653 responsible for drawing the spanners is
3654 @code{ly:line-spanner::print}. This routine determines the
3655 exact location of the two @i{span points} and draws a line
3656 between them, in the style requested.
3658 Here is an example showing the different line styles available,
3659 and how to tune them.
3661 @lilypond[ragged-right,verbatim,quote]
3664 \once \override Glissando.style = #'dashed-line
3666 \override Glissando.style = #'dotted-line
3668 \override Glissando.style = #'zigzag
3670 \override Glissando.style = #'trill
3675 The locations of the end-points of the spanner are computed
3676 on-the-fly for every graphic object, but it is possible to
3680 @lilypond[ragged-right,verbatim,quote]
3683 \once \override Glissando.bound-details.right.Y = #-2
3688 The value for @code{Y} is set to @w{@code{-2}} for the right end
3689 point. The left side may be similarly adjusted by specifying
3690 @code{left} instead of @code{right}.
3692 If @code{Y} is not set, the value is computed from the vertical
3693 position of the left and right attachment points of the spanner.
3695 Other adjustments of spanners are possible, for details, see
3698 @node Rotating objects
3699 @subsection Rotating objects
3701 Both layout objects and elements of markup text can be rotated by
3702 any angle about any point, but the method of doing so differs.
3705 * Rotating layout objects::
3709 @node Rotating layout objects
3710 @unnumberedsubsubsec Rotating layout objects
3712 @cindex rotating objects
3713 @cindex objects, rotating
3715 All layout objects which support the @code{grob-interface} can be
3716 rotated by setting their @code{rotation} property. This takes a
3717 list of three items: the angle of rotation counter-clockwise,
3718 and the x and y coordinates of the point relative to the object's
3719 reference point about which the rotation is to be performed. The
3720 angle of rotation is specified in degrees and the coordinates in
3723 The angle of rotation and the coordinates of the rotation point must
3724 be determined by trial and error.
3726 @cindex hairpins, angled
3727 @cindex angled hairpins
3729 There are only a few situations where the rotation of layout
3730 objects is useful; the following example shows one situation where
3733 @lilypond[quote,fragment,verbatim]
3735 \override Hairpin.rotation = #'(20 -1 0)
3739 @node Rotating markup
3740 @unnumberedsubsubsec Rotating markup
3742 All markup text can be rotated to lie at any angle by prefixing it
3743 with the @code{\rotate} command. The command takes two arguments:
3744 the angle of rotation in degrees counter-clockwise and the text to
3745 be rotated. The extents of the text are not rotated: they take
3746 their values from the extremes of the x and y coordinates of the
3747 rotated text. In the following example the
3748 @code{outside-staff-priority} property for text is set to @code{#f}
3749 to disable the automatic collision avoidance, which would push some
3750 of the text too high.
3752 @lilypond[quote,fragment,verbatim]
3753 \override TextScript.outside-staff-priority = ##f
3754 g4^\markup { \rotate #30 "a G" }
3755 b^\markup { \rotate #30 "a B" }
3756 des'^\markup { \rotate #30 "a D-Flat" }
3757 fis'^\markup { \rotate #30 "an F-Sharp" }
3760 @node Advanced tweaks
3761 @section Advanced tweaks
3763 This section discusses various approaches to fine tuning the
3764 appearance of the printed score.
3767 * Aligning objects::
3768 * Vertical grouping of grobs::
3769 * Modifying stencils::
3770 * Modifying shapes::
3771 * Modifying broken spanners::
3772 * Unpure-pure containers::
3777 @rlearning{Tweaking output},
3778 @rlearning{Other sources of information}.
3781 @ref{Explaining the Internals Reference},
3782 @ref{Modifying properties}.
3785 @rextend{Interfaces for programmers}.
3788 @file{scm/define-grobs.scm}.
3791 @rlsr{Tweaks and overrides}.
3793 Internals Reference:
3794 @rinternals{All layout objects}.
3797 @node Aligning objects
3798 @subsection Aligning objects
3800 Graphical objects which support the @code{self-alignment-interface}
3801 and/or the @code{side-position-interface} can be aligned to a previously
3802 placed object in a variety of ways. For a list of these objects, see
3803 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3805 All graphical objects have a reference point, a horizontal extent and a
3806 vertical extent. The horizontal extent is a pair of numbers
3807 giving the displacements from the reference point of the left and
3808 right edges, displacements to the left being negative. The vertical
3809 extent is a pair of numbers giving the displacement from the reference
3810 point to the bottom and top edges, displacements down being negative.
3812 An object's position on a staff is given by the values of the
3813 @code{X-offset} and @code{Y-offset} properties. The value of
3814 @code{X-offset} gives the displacement from the X coordinate of
3815 the reference point of the parent object, and the value of
3816 @code{Y-offset} gives the displacement from the center line of the
3817 staff. The values of @code{X-offset} and @code{Y-offset} may
3818 be set directly or may be set to be calculated by procedures in order
3819 to achieve alignment with the parent object.
3821 @warning{Many objects have special positioning considerations which
3822 cause any setting of @code{X-offset} or @code{Y-offset} to be
3823 ignored or modified, even though the object supports the
3824 @code{self-alignment-interface}. Overriding the @code{X-offset}
3825 or @code{Y-offset} properties to a fixed value causes the respective
3826 @code{self-alignment} property to be disregarded.}
3828 For example, an accidental can be repositioned vertically by setting
3829 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3831 Rehearsal marks may be aligned with breakable objects such as bar
3832 lines, clef symbols, time signature symbols and key signatures. There
3833 are special properties to be found in the @code{break-aligned-interface}
3834 for positioning rehearsal marks on such objects.
3838 @ref{Using the break-alignable-interface}.
3841 @rextend{Callback functions}.
3844 * Setting X-offset and Y-offset directly::
3845 * Using the side-position-interface::
3846 * Using the self-alignment-interface::
3847 * Using the break-alignable-interface::
3850 @node Setting X-offset and Y-offset directly
3851 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3853 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3854 properties of many objects. The following example shows three
3855 notes with the default fingering position and the positions with @code{X-offset}
3856 and @code{Y-offset} modified.
3858 @lilypond[verbatim,fragment,quote]
3865 -\tweak X-offset #-1
3872 @node Using the side-position-interface
3873 @unnumberedsubsubsec Using the @code{side-position-interface}
3875 An object which supports the @code{side-position-interface} can be
3876 placed next to its parent object so that
3877 the specified edges of the two objects touch. The object may be
3878 placed above, below, to the right or to the left of the parent.
3879 The parent cannot be specified; it is determined by the order of
3880 elements in the input stream. Most objects have the associated
3881 note head as their parent.
3883 The values of the @code{side-axis} and @code{direction} properties
3884 determine where the object is to be placed, as follows:
3886 @c TODO add an example of each to the table
3888 @multitable @columnfractions .3 .3 .3
3889 @headitem @code{side-axis} @tab @code{direction} @tab
3890 @headitem property @tab property @tab Placement
3892 @item @code{0} @tab @code{-1} @tab left
3893 @item @code{0} @tab @code{1} @tab right
3894 @item @code{1} @tab @code{-1} @tab below
3895 @item @code{1} @tab @code{1} @tab above
3899 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3900 the procedure @code{ly:side-position-interface::x-aligned-side}.
3901 This procedure will return the correct value of @code{X-offset} to
3902 place the object to the left or right side of the parent according
3903 to value of @code{direction}.
3905 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3906 the procedure @code{ly:side-position-interface::y-aligned-side}.
3907 This procedure will return the correct value of @code{Y-offset} to
3908 place the object to the top or bottom of the parent according
3909 to value of @code{direction}.
3911 @c TODO Add examples
3913 @node Using the self-alignment-interface
3914 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3916 @subsubsubheading Self-aligning objects horizontally
3918 The horizontal alignment of an object which supports the
3919 @code{self-alignment-interface} is controlled by the value of
3920 the @code{self-alignment-X} property, provided the object's
3921 @code{X-offset} property is set to
3922 @code{ly:self-alignment-interface::x-aligned-on-self}.
3923 @code{self-alignment-X} may be given any
3924 real value, in units of half the total X extent of the
3925 object. Negative values move the object to the right, positive
3926 to the left. A value of @code{0} centers the object on the
3927 reference point of its parent, a value of @w{@code{-1}} aligns the
3928 left edge of the object on the reference point of its parent,
3929 and a value of @code{1} aligns the right edge of the object on the
3930 reference point of its parent. The symbols @code{LEFT},
3931 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3932 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3934 Normally the @code{\override} command would be used to modify the
3935 value of @code{self-alignment-X}, but the @code{\tweak} command
3936 can be used to separately align several annotations on a single
3939 @lilypond[quote,verbatim,fragment]
3941 -\tweak self-alignment-X #-1
3943 -\tweak self-alignment-X #0
3945 -\tweak self-alignment-X #RIGHT
3947 -\tweak self-alignment-X #-2.5
3948 ^"aligned further to the right"
3951 @subsubsubheading Self-aligning objects vertically
3953 Objects may be aligned vertically in an analogous way to aligning
3954 them horizontally if the @code{Y-offset} property is set to
3955 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3956 other mechanisms are often involved in vertical alignment: the
3957 value of @code{Y-offset} is just one variable taken into account.
3958 This may make adjusting the value of some objects tricky.
3959 The units are just half the vertical extent of the object, which
3960 is usually quite small, so quite large numbers may be required.
3961 A value of @w{@code{-1}} aligns the lower edge of the object with
3962 the reference point of the parent object, a value of @code{0}
3963 aligns the center of the object with the reference point of the
3964 parent, and a value of @code{1} aligns the top edge of the object
3965 with the reference point of the parent. The symbols @code{DOWN},
3966 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3967 @code{0}, and @code{1}, respectively.
3969 @subsubsubheading Self-aligning objects in both directions
3971 By setting both @code{X-offset} and @code{Y-offset}, an object may
3972 be aligned in both directions simultaneously.
3974 The following example shows how to adjust a fingering mark so
3975 that it nestles close to the note head.
3977 @lilypond[quote,verbatim,fragment]
3979 -\tweak self-alignment-X #0.5 % move horizontally left
3980 -\tweak Y-offset #ly:self-alignment-interface::y-aligned-on-self
3981 -\tweak self-alignment-Y #-1 % move vertically up
3986 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3988 @c Cannot document as they do not seem to operate consistently on all objects -td
3989 @c TODO investigate further
3991 The @code{aligned-on-parent} procedures are used in the same way
3992 as the @code{aligned-on-self} procedures, they difference being
3993 that they permit an object to be aligned with the @emph{edges} of
3994 the parent rather than the parent's reference point. The following
3995 example shows the difference:
3999 @lilypond[verbatim,quote]
4005 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
4007 @c Cannot document as they do not seem to operate consistently on all objects -td
4008 @c TODO investigate further
4012 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
4014 @node Using the break-alignable-interface
4015 @unnumberedsubsubsec Using the @code{break-alignable-interface}
4017 @cindex align to objects
4018 @cindex break-align-symbols
4020 Rehearsal marks and bar numbers may be aligned with notation
4021 objects other than bar lines. These objects include @code{ambitus},
4022 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
4023 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
4024 @code{time-signature}.
4026 Each type of object has its own default reference point, to which
4027 rehearsal marks are aligned:
4029 @lilypond[verbatim,quote,fragment]
4030 % The rehearsal mark will be aligned to the right edge of the Clef
4031 \override Score.RehearsalMark.break-align-symbols = #'(clef)
4036 % The rehearsal mark will be aligned to the left edge of the Time Signature
4037 \override Score.RehearsalMark.break-align-symbols = #'(time-signature)
4043 % The rehearsal mark will be centered above the Breath Mark
4044 \override Score.RehearsalMark.break-align-symbols = #'(breathing-sign)
4053 A list of possible target alignment objects may be specified. If
4054 some of the objects are invisible at that point due to the setting
4055 of @code{break-visibility} or the explicit visibility settings for
4056 keys and clefs, the rehearsal mark or bar number is aligned to the
4057 first object in the list which is visible. If no objects in the
4058 list are visible the object is aligned to the bar line. If the bar
4059 line is invisible the object is aligned to the place where the bar
4062 @lilypond[verbatim,quote,fragment]
4063 % The rehearsal mark will be aligned to the right edge of the Key Signature
4064 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
4069 % The rehearsal mark will be aligned to the right edge of the Clef
4070 \set Staff.explicitKeySignatureVisibility = #all-invisible
4071 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
4076 % The rehearsal mark will be centered above the Bar Line
4077 \set Staff.explicitKeySignatureVisibility = #all-invisible
4078 \set Staff.explicitClefVisibility = #all-invisible
4079 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
4086 The alignment of the rehearsal mark relative to the notation object
4087 can be changed, as shown in the following example. In a score with
4088 multiple staves, this setting should be done for all the staves.
4090 @lilypond[verbatim,quote,fragment]
4091 % The RehearsalMark will be aligned with the right edge of the Key Signature
4092 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
4098 % The RehearsalMark will be centered above the Key Signature
4099 \once \override Score.KeySignature.break-align-anchor-alignment = #CENTER
4103 % The RehearsalMark will be aligned with the left edge of the Key Signature
4104 \once \override Score.KeySignature.break-align-anchor-alignment = #LEFT
4110 The rehearsal mark can also be offset to the right or left of the left
4111 edge by an arbitrary amount. The units are staff-spaces:
4113 @lilypond[verbatim,quote,fragment]
4114 % The RehearsalMark will be aligned with the left edge of the Key Signature
4115 % and then shifted right by 3.5 staff-spaces
4116 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
4117 \once \override Score.KeySignature.break-align-anchor = #3.5
4121 % The RehearsalMark will be aligned with the left edge of the Key Signature
4122 % and then shifted left by 2 staff-spaces
4123 \once \override Score.KeySignature.break-align-anchor = #-2
4130 @node Vertical grouping of grobs
4131 @subsection Vertical grouping of grobs
4133 @c TODO Expand this section
4135 The VerticalAlignment and VerticalAxisGroup grobs work together.
4136 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
4137 etc. VerticalAlignment then vertically aligns the different grobs
4138 grouped together by VerticalAxisGroup. There is usually only one
4139 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
4143 @node Modifying stencils
4144 @subsection Modifying stencils
4146 All layout objects have a @code{stencil} property which is part of
4147 the @code{grob-interface}. By default, this property is usually
4148 set to a function specific to the object that is tailor-made to
4149 render the symbol which represents it in the output. For example,
4150 the standard setting for the @code{stencil} property of the
4151 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
4153 The standard symbol for any object can be replaced by modifying the
4154 @code{stencil} property to reference a different, specially-written,
4155 procedure. This requires a high level of knowledge of the internal
4156 workings of LilyPond, but there is an easier way which can often
4157 produce adequate results.
4159 This is to set the @code{stencil} property to the procedure which
4160 prints text -- @code{ly:text-interface::print} -- and to add a
4161 @code{text} property to the object which is set to contain the
4162 markup text which produces the required symbol. Due to the
4163 flexibility of markup, much can be achieved -- see in particular
4164 @ref{Graphic notation inside markup}.
4166 The following example demonstrates this by changing the note head
4167 symbol to a cross within a circle.
4169 @lilypond[verbatim,quote]
4171 \once \override NoteHead.stencil = #ly:text-interface::print
4172 \once \override NoteHead.text = \markup {
4174 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
4175 \musicglyph #"noteheads.s2cross"
4183 Any of the glyphs in the feta Font can be supplied to the
4184 @code{\musicglyph} markup command -- see @ref{The Feta font}.
4186 @c TODO Add inserting eps files or ref to later
4188 @c TODO Add inserting Postscript or ref to later
4192 @ref{Graphic notation inside markup},
4193 @ref{Formatting text},
4194 @ref{Text markup commands},
4195 @ref{The Feta font}.
4198 @node Modifying shapes
4199 @subsection Modifying shapes
4202 * Modifying ties and slurs::
4205 @node Modifying ties and slurs
4206 @unnumberedsubsubsec Modifying ties and slurs
4208 @cindex slurs, modifying
4209 @cindex ties, modifying
4210 @cindex Bézier curves, control points
4211 @cindex control points, Bézier curves
4213 @code{Tie}s, @code{Slur}s, @code{PhrasingSlur}s,
4214 @code{LaissezVibrerTie}s and @code{RepeatTie}s are all drawn as
4215 third-order Bézier curves. If the shape of the tie or slur which
4216 is calculated automatically is not optimum, the shape may be
4217 modified manually in two ways:
4221 by specifying the displacements to be made to the control points
4222 of the automatically calculated Bézier curve, or
4225 by explicitly specifying the positions of the four control points
4226 required to define the wanted curve.
4229 Both methods are explained below. The first method is more suitable
4230 if only slight adjustments to the curve are required; the second may
4231 be better for creating curves which are related to just a single
4234 @subsubsubheading Cubic Bézier curves
4236 Third-order or cubic Bézier curves are defined by four control
4237 points. The first and fourth control points are precisely the
4238 starting and ending points of the curve. The intermediate two
4239 control points define the shape. Animations showing how the curve
4240 is drawn can be found on the web, but the following description
4241 may be helpful. The curve starts from the first control point
4242 heading directly towards the second, gradually bending over to
4243 head towards the third and continuing to bend over to head towards
4244 the fourth, arriving there travelling directly from the third
4245 control point. The curve is entirely contained in the
4246 quadrilateral defined by the four control points. Translations,
4247 rotations and scaling of the control points all result in exactly
4248 the same operations on the curve.
4250 @subsubsubheading Specifying displacements from current control points
4252 @cindex shaping slurs and ties
4255 In this example the automatic placement of the tie is not optimum,
4256 and @code{\tieDown} would not help.
4258 @lilypond[verbatim,quote]
4262 \relative { r4 <g' c,> <g c,> <g c,> }
4266 Adjusting the control points of the tie with @code{\shape} allows
4267 the collisions to be avoided.
4269 The syntax of @code{\shape} is
4272 [-]@code{\shape} @var{displacements} @var{item}
4275 This will reposition the control-points of @var{item} by the amounts
4276 given by @var{displacements}. The @var{displacements} argument is a
4277 list of number pairs or a list of such lists. Each element of a pair
4278 represents the displacement of one of the coordinates of a
4279 control-point. If @var{item} is a string, the result is
4280 @code{\once\override} for the specified grob type. If @var{item} is
4281 a music expression, the result is the same music expression with an
4282 appropriate tweak applied.
4284 In other words, the @code{\shape} function can act as either a
4285 @code{\once\override} command or a @code{\tweak} command depending
4286 on whether the @var{item} argument is a grob name, like @qq{Slur},
4287 or a music expression, like @qq{(}. The @var{displacements} argument
4288 specifies the displacements of the four control points as a list of
4289 four pairs of (dx . dy) values in units of staff-spaces (or a list
4290 of such lists if the curve has more than one segment).
4292 The leading hyphen is required if and only if the @code{\tweak} form
4295 So, using the same example as above and the @code{\once\override}
4296 form of @code{\shape}, this will raise the tie by half a staff-space:
4298 @lilypond[verbatim,quote]
4301 \shape #'((0 . 0.5) (0 . 0.5) (0 . 0.5) (0 . 0.5)) Tie
4305 \relative { r4 <g' c,> <g c,> <g c,> }
4309 This positioning of the tie is better, but maybe it should be raised
4310 more in the center. The following example does this, this time using
4311 the alternative @code{\tweak} form:
4313 @lilypond[verbatim,quote]
4316 e'1-\shape #'((0 . 0.5) (0 . 1) (0 . 1) (0 . 0.5)) ~ e'
4319 \relative { r4 <g' c,> <g c,> <g c,> }
4323 Changes to the horizontal positions of the control points may be made
4324 in the same way, and two different curves starting at the same
4325 musical moment may also be shaped:
4327 @lilypond[verbatim,quote,ragged-right]
4329 c''8(\( a) a'4 e c\)
4330 \shape #'((0.7 . -0.4) (0.5 . -0.4) (0.3 . -0.3) (0 . -0.2)) Slur
4331 \shape #'((0 . 0) (0 . 0.5) (0 . 0.5) (0 . 0)) PhrasingSlur
4336 The @code{\shape} function can also displace the control points of
4337 curves which stretch across line breaks. Each piece of the broken
4338 curve can be given its own list of offsets. If changes to a
4339 particular segment are not needed, the empty list can serve as a
4340 placeholder. In this example the line break makes the single slur
4343 @lilypond[verbatim,quote,ragged-right]
4351 Changing the shapes of the two halves of the slur makes it clearer
4352 that the slur continues over the line break:
4354 @lilypond[verbatim,quote,ragged-right]
4355 % () may be used as a shorthand for ((0 . 0) (0 . 0) (0 . 0) (0 . 0))
4356 % if any of the segments does not need to be changed
4359 (( 0 . 0) (0 . 0) (0 . 0) (0 . 1))
4360 ((0.5 . 1.5) (1 . 0) (0 . 0) (0 . -1.5))
4368 If an S-shaped curve is required the control points must always be
4369 adjusted manually --- LilyPond will never select such shapes
4372 @lilypond[verbatim,quote]
4374 c8( e b-> f d' a e-> g)
4375 \shape #'((0 . -1) (5.5 . -0.5) (-5.5 . -10.5) (0 . -5.5)) PhrasingSlur
4376 c8\( e b-> f d' a e-> g\)
4380 @subsubsubheading Specifying control points explicitly
4382 The coordinates of the Bézier control points are specified in units
4383 of staff-spaces. The X@tie{}coordinate is relative to the reference
4384 point of the note to which the tie or slur is attached, and the
4385 Y@tie{}coordinate is relative to the staff center line. The
4386 coordinates are specified as a list of four pairs of decimal numbers
4387 (reals). One approach is to estimate the coordinates of the two
4388 end points, and then guess the two intermediate points. The optimum
4389 values are then found by trial and error. Be aware that these values
4390 may need to be manually adjusted if any further changes are made to
4391 the music or the layout.
4393 One situation where specifying the control points explicitly is
4394 preferable to specifying displacements is when they need to be
4395 specified relative to a single note. Here is an example of this.
4396 It shows one way of indicating a slur extending into alternative
4397 sections of a volta repeat.
4399 @lilypond[verbatim,quote]
4402 \repeat volta 3 { c4 d( e f }
4407 % create a slur and move it to a new position
4408 % the <> is just an empty chord to carry the slur termination
4409 -\tweak control-points #'((-2 . 3.8) (-1 . 3.9) (0 . 4) (1 . 3.4)) ( <> )
4414 % create a slur and move it to a new position
4415 -\tweak control-points #'((-2 . 3) (-1 . 3.1) (0 . 3.2) (1 . 2.4)) ( <> )
4423 It is not possible to modify shapes of ties or slurs by changing
4424 the @code{control-points} property if there are multiple ties or slurs
4425 at the same musical moment -- the @code{\tweak} command will also not
4426 work in this case. However, the @code{tie-configuration} property of
4427 @code{TieColumn} can be overridden to set start line and direction as
4431 Internals Reference:
4432 @rinternals{TieColumn}.
4435 @node Modifying broken spanners
4436 @subsection Modifying broken spanners
4439 * Using alterBroken::
4442 @node Using alterBroken
4443 @unnumberedsubsubsec Using @code{\alterBroken}
4445 @cindex spanners, modifying
4446 @cindex broken spanners, modifying
4447 @funindex \alterBroken
4449 When a spanner crosses a line break or breaks, each piece
4450 inherits the attributes of the original spanner. Thus, ordinary
4451 tweaking of a broken spanner applies the same modifications to
4452 each of its segments. In the example below, overriding
4453 @code{thickness} affects the slur on either side of the line
4456 @lilypond[verbatim,quote,ragged-right]
4459 \once\override Slur.thickness = 10
4466 Independently modifying the appearance of individual pieces
4467 of a broken spanner is possible with the @code{\alterBroken}
4468 command. This command can produce either an @code{\override}
4469 or a @code{\tweak} of a spanner property.
4471 The syntax for @code{\alterBroken} is
4474 [-]@code{\alterBroken} @var{property} @var{values} @var{item}
4477 The argument @var{values} is a list of values, one for each
4478 broken piece. If @var{item} is a grob name like @code{Slur} or
4479 @code{Staff.PianoPedalBracket}, the result is an @code{\override}
4480 of the specified grob type. If @var{item} is a music expression
4481 such as @qq{(} or @qq{[} the result is the same music expression
4482 with an appropriate tweak applied.
4484 The leading hyphen must be used with the @code{\tweak} form. Do
4485 not add it when @code{\alterBroken} is used as an
4488 In its @code{\override} usage, @code{\alterBroken} may be
4489 prefaced by @code{\once} or @code{\temporary} and reverted by
4490 using @code{\revert} with @var{property}.
4492 The following code applies an independent @code{\override} to
4493 each of the slur segments in the previous example:
4495 @lilypond[verbatim,quote,ragged-right]
4498 \alterBroken thickness #'(10 1) Slur
4505 The @code{\alterBroken} command may be used with any spanner
4506 object, including @code{Tie}, @code{PhrasingSlur}, @code{Beam}
4507 and @code{TextSpanner}. For example, an editor preparing a
4508 scholarly edition may wish to indicate the absence of part of a
4509 phrasing slur in a source by dashing only the segment which has
4510 been added. The following example illustrates how this can be
4511 done, in this case using the @code{\tweak} form of the command:
4513 @lilypond[verbatim,quote,ragged-right]
4514 % The empty list is conveniently used below, because it is the
4515 % default setting of dash-definition, resulting in a solid curve.
4517 c''2-\alterBroken dash-definition #'(() ((0 1.0 0.4 0.75))) \(e
4523 It is important to understand that @code{\alterBroken} will set
4524 each piece of a broken spanner to the corresponding value in
4525 @var{values}. When there are fewer values than pieces, any
4526 additional piece will be assigned the empty list. This may lead
4527 to undesired results if the layout property is not set to the
4528 empty list by default. In such cases, each segment should be
4529 assigned an appropriate value.
4532 Line breaks may occur in different places following changes in
4533 layout. Settings chosen for @code{\alterBroken} may be unsuitable
4534 for a spanner that is no longer broken or is split into more
4535 segments than before. Explicit use of @code{\break} can guard
4536 against this situation.
4538 The @code{\alterBroken} command is ineffective for spanner
4539 properties accessed before line-breaking such as
4544 @rextend{Difficult tweaks}.
4547 @node Unpure-pure containers
4548 @subsection Unpure-pure containers
4550 @cindex Scheme, pure containers
4551 @cindex Scheme, unpure containers
4552 @cindex pure containers, Scheme
4553 @cindex unpure containers, Scheme
4554 @cindex horizontal spacing, overriding
4556 Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
4557 calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
4558 Scheme function instead of a literal (i.e. a number or pair).
4560 For certain grobs, the @code{Y-extent} is based on the @code{stencil}
4561 property, overriding the stencil property of one of these will
4562 require an additional @code{Y-extent} override with an unpure-pure
4563 container. When a function overrides a @code{Y-offset} and/or
4564 @code{Y-extent} it is assumed that this will trigger line breaking
4565 calculations too early during compilation. So the function is not
4566 evaluated at all (usually returning a value of @samp{0} or
4567 @samp{'(0 . 0)}) which can result in collisions. A @q{pure} function
4568 will not affect properties, objects or grob suicides and therefore will
4569 always have its Y-axis-related evaluated correctly.
4571 Currently, there are about thirty functions that are already considered
4572 @q{pure} and Unpure-pure containers are a way to set functions not on
4573 this list as @q{pure}. The @q{pure} function is evaluated @emph{before}
4574 any line-breaking and so the horizontal spacing can be adjusted
4575 @q{in time}. The @q{unpure} function is then evaluated @emph{after}
4578 @warning{As it is difficult to always know which functions are on this
4579 list we recommend that any @q{pure} functions you create do not use
4580 @code{Beam} or @code{VerticalAlignment} grobs.}
4582 An unpure-pure container is constructed as follows;
4584 @code{(ly:make-unpure-pure-container f0 f1)}
4586 where @code{f0} is a function taking @var{n} arguments (@var{n >= 1})
4587 and the first argument must always be the grob. This is the function
4588 that gives the actual result. @var{f1} is the function being labeled
4589 as @q{pure} that takes @var{n + 2} arguments. Again, the first argument
4590 must always still be the grob but the second and third are @q{start}
4591 and @q{end} arguments.
4593 @var{start} and @var{end} are, for all intents and purposes, dummy
4594 values that only matter for @code{Spanners} (i.e @code{Hairpin} or
4595 @code{Beam}), that can return different height estimations based on a
4596 starting and ending column.
4598 The rest are the other arguments to the first function (which
4599 may be none if @var{n = 1}).
4601 The results of the second function are used as an approximation of the
4602 value needed which is then used by the first function to get the real
4603 value which is then used for fine-tuning much later during the spacing
4606 @lilypond[verbatim,quote,ragged-right]
4607 #(define (square-line-circle-space grob)
4608 (let* ((pitch (ly:event-property (ly:grob-property grob 'cause) 'pitch))
4609 (notename (ly:pitch-notename pitch)))
4610 (if (= 0 (modulo notename 2))
4611 (make-circle-stencil 0.5 0.0 #t)
4612 (make-filled-box-stencil '(0 . 1.0)
4615 squareLineCircleSpace = {
4616 \override NoteHead.stencil = #square-line-circle-space
4619 smartSquareLineCircleSpace = {
4620 \squareLineCircleSpace
4621 \override NoteHead.Y-extent =
4622 #(ly:make-unpure-pure-container
4623 ly:grob::stencil-height
4624 (lambda (grob start end) (ly:grob::stencil-height grob)))
4627 \new Voice \with { \remove "Stem_engraver" }
4629 \squareLineCircleSpace
4631 \smartSquareLineCircleSpace
4636 In the first measure, without the unpure-pure container, the spacing
4637 engine does not know the width of the note head and lets it collide with
4638 the accidentals. In the second measure, with unpure-pure containers,
4639 the spacing engine knows the width of the note heads and avoids the
4640 collision by lengthening the line accordingly.
4642 Usually for simple calculations nearly-identical functions for
4643 both the @q{unpure} and @q{pure} parts can be used, by only
4644 changing the number of arguments passed to, and the scope of, the
4645 function. This use case is frequent enough that
4646 @code{ly:make-unpure-pure-container} constructs such a second
4647 function by default when called with only one function argument.
4649 @warning{If a function is labeled as @q{pure} and it turns out not to
4650 be, the results can be unexpected.}
4653 @node Using music functions
4654 @section Using music functions
4656 @c TODO -- add @seealso, etc. to these subsections
4658 Where tweaks need to be reused with different music expressions,
4659 it is often convenient to make the tweak part of a @emph{music
4660 function}. In this section, we discuss only @emph{substitution}
4661 functions, where the object is to substitute a variable into a
4662 piece of LilyPond input code. Other more complex functions are
4663 described in @rextend{Music functions}.
4666 * Substitution function syntax::
4667 * Substitution function examples::
4670 @node Substitution function syntax
4671 @subsection Substitution function syntax
4673 Making a function that substitutes a variable into LilyPond
4674 code is easy. The general form of these functions is
4678 #(define-music-function
4679 (@var{arg1} @var{arg2} @dots{})
4680 (@var{type1?} @var{type2?} @dots{})
4682 @var{@dots{}music@dots{}}
4689 @multitable @columnfractions .33 .66
4690 @item @code{@var{argN}}
4691 @tab @var{n}th argument
4693 @item @code{@var{typeN?}}
4694 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
4695 must return @code{#t}.
4697 @item @code{@var{@dots{}music@dots{}}}
4698 @tab normal LilyPond input, using @code{$} (in places where only
4699 Lilypond constructs are allowed) or @code{#} (to use it as a Scheme
4700 value or music function argument or music inside of music lists) to
4705 The list of type predicates is required. Some of the most common
4706 type predicates used in music functions are:
4710 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
4722 For a list of available type predicates, see
4723 @ref{Predefined type predicates}. User-defined type predicates
4728 @ref{Predefined type predicates}.
4731 @rextend{Music functions}.
4734 @file{lily/music-scheme.cc},
4736 @file{scm/lily.scm}.
4739 @node Substitution function examples
4740 @subsection Substitution function examples
4742 This section introduces some substitution function examples.
4743 These are not intended to be exhaustive, but rather to demonstrate
4744 some of the possibilities of simple substitution functions.
4746 In the first example, a function is defined that simplifies
4747 setting the padding of a TextScript:
4749 @lilypond[quote,verbatim,ragged-right]
4751 #(define-music-function
4755 \once \override TextScript.padding = #padding
4759 c''4^"piu mosso" b a b
4761 c4^"piu mosso" b a b
4763 c4^"piu mosso" b a b
4767 In addition to numbers, we can use music expressions such
4768 as notes for arguments to music functions:
4770 @lilypond[quote,verbatim,ragged-right]
4772 #(define-music-function
4776 \tweak NoteHead.stencil #ly:text-interface::print
4777 \tweak NoteHead.text
4778 \markup \musicglyph #"custodes.mensural.u0"
4779 \tweak Stem.stencil ##f
4783 \relative { c'4 d e f \custosNote g }
4787 Both of those functions are simple single expressions where only
4788 the last element of a function call or override is missing. For
4789 those particular function definitions, there is a simpler
4790 alternative syntax, namely just writing out the constant part of
4791 the expression and replacing its final missing element with
4794 @lilypond[quote,verbatim,ragged-right]
4796 \once \override TextScript.padding = \etc
4799 c''4^"piu mosso" b a b
4801 c4^"piu mosso" b a b
4803 c4^"piu mosso" b a b
4807 @lilypond[quote,verbatim,ragged-right]
4809 \tweak NoteHead.stencil #ly:text-interface::print
4810 \tweak NoteHead.text
4811 \markup \musicglyph #"custodes.mensural.u0"
4812 \tweak Stem.stencil ##f
4815 \relative { c'4 d e f \custosNote g }
4819 Substitution functions with multiple arguments can be defined:
4821 @lilypond[quote,verbatim,ragged-right]
4823 #(define-music-function
4827 \once \override Score.MetronomeMark.padding = #padding
4828 \tempo \markup { \bold #tempotext }
4832 \tempo \markup { "Low tempo" }
4834 \tempoPadded #4.0 "High tempo"
4839 @c TODO: add appropriate @@ref's here.