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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::
63 * Keeping contexts alive::
64 * Modifying context plug-ins::
65 * Changing context default settings::
66 * Defining new contexts::
67 * Context layout order::
72 @rlearning{Contexts and engravers}.
75 @file{ly/engraver-init.ly},
76 @file{ly/performer-init.ly}.
79 @rlsr{Contexts and engravers}.
82 @rinternals{Contexts},
83 @rinternals{Engravers and Performers}.
86 @node Contexts explained
87 @subsection Contexts explained
90 @c TODO Rethink and rewrite
92 >> > > - list of contexts: my *danger unmaintainable*
93 >> > > alarm just went off. I'm
95 I knew it would... And leaving out some of them is perfectly fine
97 I do think that a list like this, with the main contexts and a
99 description of what they do (perhaps also with a note about what
101 behavior is associated with each of them, but this may be
103 should be there, and then we could simply list the remaining ones
105 further explanation and with links to the IR.
108 @c TODO Improve layout, order and consistency of wording -td
110 @c TODO Add introduction which explains contexts in generality -td
112 @c TODO Describe propagation of property values -td
114 Contexts are arranged hierarchically:
117 * Score - the master of all contexts::
118 * Top-level contexts - staff containers::
119 * Intermediate-level contexts - staves::
120 * Bottom-level contexts - voices::
123 @node Score - the master of all contexts
124 @unnumberedsubsubsec Score - the master of all contexts
126 This is the top level notation context. No other context can
127 contain a Score context. By default the Score context handles
128 the administration of time signatures and makes sure that items
129 such as clefs, time signatures, and key-signatures are aligned
132 A Score context is instantiated implicitly when a
133 @code{\score @{@dots{}@}} or @code{\layout @{@dots{}@}} block is
136 @node Top-level contexts - staff containers
137 @unnumberedsubsubsec Top-level contexts - staff containers
139 @strong{@emph{StaffGroup}}
141 Groups staves while adding a bracket on the left side, grouping
142 the staves together. The bar lines of the contained staves are
143 connected vertically. @code{StaffGroup} only consists of a collection
144 of staves, with a bracket in front and spanning bar lines.
146 @strong{@emph{ChoirStaff}}
148 Identical to @code{StaffGroup} except that the bar lines of the
149 contained staves are not connected vertically.
151 @strong{@emph{GrandStaff}}
153 A group of staves, with a brace on the left side, grouping the
154 staves together. The bar lines of the contained staves are
155 connected vertically.
157 @strong{@emph{PianoStaff}}
159 Just like @code{GrandStaff}, but with support for instrument names
160 to the left of each system.
162 @node Intermediate-level contexts - staves
163 @unnumberedsubsubsec Intermediate-level contexts - staves
165 @strong{@emph{Staff}}
167 Handles clefs, bar lines, keys, accidentals. It can contain
168 @code{Voice} contexts.
170 @strong{@emph{RhythmicStaff}}
172 Like @code{Staff} but for printing rhythms. Pitches are ignored;
173 the notes are printed on one line.
175 @strong{@emph{TabStaff}}
177 Context for generating tablature. By default lays the music
178 expression out as a guitar tablature, printed on six lines.
180 @strong{@emph{DrumStaff}}
182 Handles typesetting for percussion. Can contain @code{DrumVoice}
184 @strong{@emph{VaticanaStaff}}
186 Same as @code{Staff}, except that it is designed for typesetting
187 a piece in gregorian style.
189 @strong{@emph{MensuralStaff}}
191 Same as @code{Staff}, except that it is designed for typesetting
192 a piece in mensural style.
194 @node Bottom-level contexts - voices
195 @unnumberedsubsubsec Bottom-level contexts - voices
197 Voice-level contexts initialise certain properties and start
198 appropriate engravers. Being bottom-level contexts, they cannot
199 contain other contexts.
201 @strong{@emph{Voice}}
203 Corresponds to a voice on a staff. This context handles the
204 conversion of dynamic signs, stems, beams, super- and sub-scripts,
205 slurs, ties, and rests. You have to instantiate this explicitly
206 if you require multiple voices on the same staff.
208 @strong{@emph{VaticanaVoice}}
210 Same as @code{Voice}, except that it is designed for typesetting
211 a piece in gregorian style.
213 @strong{@emph{MensuralVoice}}
215 Same as @code{Voice}, with modifications for typesetting a piece in
218 @strong{@emph{Lyrics}}
220 Corresponds to a voice with lyrics. Handles the printing of a
221 single line of lyrics.
223 @strong{@emph{DrumVoice}}
225 The voice context used in a percussion staff.
227 @strong{@emph{FiguredBass}}
229 The context in which @code{BassFigure} objects are created from
230 input entered in @code{\figuremode} mode.
232 @strong{@emph{TabVoice}}
234 The voice context used within a @code{TabStaff} context. Usually
235 left to be created implicitly.
237 @strong{@emph{CueVoice}}
239 A voice context used to render notes of a reduced size, intended
240 primarily for adding cue notes to a staff, see @ref{Formatting
241 cue notes}. Usually left to be created implicitly.
243 @strong{@emph{ChordNames}}
245 Typesets chord names.
250 Then the following, which I don't know what to do with:
252 * GregorianTranscriptionVoice
253 * GregorianTranscriptionStaff
256 Engraves fretboards from chords. Not easy... Not
258 There is now some documentation on FretBoards in the NR, under
259 instrument-specific notation -- cds.
264 Hard coded entry point for LilyPond. Cannot be tuned.
266 Silently discards all musical information given to this
271 @node Creating contexts
272 @subsection Creating contexts
274 @c TODO more complete descriptions rather than learning style
276 For scores with only one voice and one staff, contexts are
277 created automatically. For more complex scores, it is necessary to
278 create them by hand. There are three commands that do this.
283 The easiest command is @code{\new}, and it also the quickest to type.
284 It is prepended to a music expression, for example
288 @cindex Context, creating
291 \new @var{type} @var{music expression}
295 where @var{type} is a context name (like @code{Staff} or
296 @code{Voice}). This command creates a new context, and starts
297 interpreting the @var{music expression} with that.
299 A practical application of @code{\new} is a score with many
300 staves. Each part that should be on its own staff, is preceded with
303 @lilypond[quote,verbatim,relative=2,ragged-right]
310 The @code{\new} command may also give a name to the context,
313 \new @var{type} = @var{id} @var{music}
315 However, this user specified name is only used if there is no other
316 context already earlier with the same name.
322 Like @code{\new}, the @code{\context} command also directs a music
323 expression to a context object, but gives the context an explicit name. The
327 \context @var{type} = @var{id} @var{music}
330 This form will search for an existing context of type @var{type}
331 called @var{id}. If that context does not exist yet, a new
332 context with the specified name is created. This is useful if
333 the context is referred to later on. For example, when
334 setting lyrics the melody is in a named context
337 \context Voice = "@b{tenor}" @var{music}
341 so the texts can be properly aligned to its notes,
344 \new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
349 Another possible use of named contexts is funneling two different
350 music expressions into one context. In the following example,
351 articulations and notes are entered separately,
355 arts = @{ s4-. s4-> @}
358 They are combined by sending both to the same @code{Voice} context,
362 \new Staff \context Voice = "A" \music
363 \context Voice = "A" \arts
366 @lilypond[quote,ragged-right]
370 \new Staff \context Voice = "A" \music
371 \context Voice = "A" \arts
375 With this mechanism, it is possible to define an Urtext (original
376 edition), with the option to put several distinct articulations on the
379 @cindex creating contexts
382 The third command for creating contexts is
384 \context @var{type} @var{music}
389 This is similar to @code{\context} with @code{= @var{id}}, but matches
390 any context of type @var{type}, regardless of its given name.
392 This variant is used with music expressions that can be interpreted at
393 several levels. For example, the @code{\applyOutput} command (see
394 @rextend{Running a function on all layout objects}). Without an explicit
395 @code{\context}, it is usually applied to @code{Voice}
398 \applyOutput #'@var{context} #@var{function} % apply to Voice
401 To have it interpreted at the @code{Score} or @code{Staff} level use
405 \applyOutput #'Score #@var{function}
406 \applyOutput #'Staff #@var{function}
411 @node Keeping contexts alive
412 @subsection Keeping contexts alive
414 @cindex contexts, keeping alive
415 @cindex contexts, lifetime
417 Contexts are usually terminated at the first musical moment in
418 which they have nothing to do. So @code{Voice} contexts die as
419 soon as they contain no events; @code{Staff} contexts die as soon
420 as all the @code{Voice} contexts within them contain no events; etc.
421 This can cause difficulties if earlier contexts which have died
422 have to be referenced, for example, when changing staves with
423 @code{\change} commands, associating lyrics with a voice with
424 @code{\lyricsto} commands, or when adding further musical events to
427 There is an exception to this general rule: just one of the
428 @code{Voice} contexts in a @code{Staff} context or in a
429 @code{<<...>>} construct will always persist to the end of the
430 enclosing @code{Staff} context or @code{<<...>>} construct, even
431 though there may be periods when it has nothing to do. The context
432 to persist in this way will be the first one encountered in the
433 first enclosed @code{@{...@}} construct, ignoring any in enclosed
434 @code{<<...>>} constructs.
436 Any context can be kept alive by ensuring it has something to do at
437 every musical moment. @code{Staff} contexts are kept alive by
438 ensuring one of their voices is kept alive. One way of doing this
439 is to add spacer rests to a voice in parallel with the real music.
440 These need to be added to every @code{Voice} context which needs to
441 be kept alive. If several voices are to be used sporadically it is
442 safest to keep them all alive rather than attempting to rely on the
443 exceptions mentioned above.
445 In the following example, both voice A and voice B are kept alive
446 in this way for the duration of the piece:
448 @lilypond[quote,verbatim]
449 musicA = \relative c'' { d4 d d d }
450 musicB = \relative c'' { g4 g g g }
453 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
454 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
459 \context Voice = "A" {
463 \context Voice = "B" {
467 \context Voice = "A" { \musicA }
468 \context Voice = "B" { \musicB }
469 \context Voice = "A" { \musicA }
480 @cindex lyrics, aligning with sporadic melody
482 The following example shows how a sporadic melody line with lyrics
483 might be written using this approach. In a real situation the
484 melody and accompaniment would consist of several different
487 @lilypond[quote,verbatim]
488 melody = \relative c'' { a4 a a a }
489 accompaniment = \relative c' { d4 d d d }
490 words = \lyricmode { These words fol -- low the mel -- o -- dy }
493 \new Staff = "music" {
495 \new Voice = "melody" {
497 s1*4 % Keep Voice "melody" alive for 4 bars
500 \new Voice = "accompaniment" {
505 \context Voice = "melody" { \melody }
506 \context Voice = "accompaniment" { \accompaniment }
508 \context Voice = "accompaniment" { \accompaniment }
510 \context Voice = "melody" { \melody }
511 \context Voice = "accompaniment" { \accompaniment }
516 \new Lyrics \with { alignAboveContext = #"music" }
517 \lyricsto "melody" { \words }
522 An alternative way, which may be better in many circumstances, is
523 to keep the melody line alive by simply including spacer notes to
524 line it up correctly with the accompaniment:
526 @lilypond[quote,verbatim]
527 melody = \relative c'' {
533 accompaniment = \relative c' {
539 words = \lyricmode { These words fol -- low the mel -- o -- dy }
543 \new Staff = "music" {
545 \new Voice = "melody" {
549 \new Voice = "accompaniment" {
555 \new Lyrics \with { alignAboveContext = #"music" }
556 \lyricsto "melody" { \words }
562 @node Modifying context plug-ins
563 @subsection Modifying context plug-ins
565 @c TODO Should this be Modifying engravers or Modifying contexts?
567 Notation contexts (like @code{Score} and @code{Staff}) not only store
568 properties, they also contain plug-ins called @q{engravers} that create
569 notation elements. For example, the @code{Voice} context contains a
570 @code{Note_heads_engraver} and the @code{Staff} context contains a
573 For a full a description of each plug-in, see
575 @rinternals{Engravers and Performers}.
578 Internals Reference @expansion{} Translation @expansion{} Engravers.
580 Every context described in
582 @rinternals{Contexts}
585 Internals Reference @expansion{} Translation @expansion{} Context.
587 lists the engravers used for that context.
590 It can be useful to shuffle around these plug-ins. This is done by
591 starting a new context with @code{\new} or @code{\context}, and
597 \new @var{context} \with @{
610 where the @dots{} should be the name of an engraver. Here is a simple
611 example which removes @code{Time_signature_engraver} and
612 @code{Clef_engraver} from a @code{Staff} context,
614 @lilypond[quote,relative=1,verbatim]
620 \remove "Time_signature_engraver"
621 \remove "Clef_engraver"
628 In the second staff there are no time signature or clef symbols. This
629 is a rather crude method of making objects disappear since it will affect
630 the entire staff. This method also influences the spacing, which may or
631 may not be desirable. More sophisticated methods of blanking objects
632 are shown in @rlearning{Visibility and color of objects}.
634 The next example shows a practical application. Bar lines and time
635 signatures are normally synchronized across the score. This is done
636 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
637 This plug-in keeps an administration of time signature, location
638 within the measure, etc. By moving these engraver from @code{Score} to
639 @code{Staff} context, we can have a score where each staff has its own
642 @cindex polymetric scores
643 @cindex Time signatures, multiple
645 @lilypond[quote,verbatim]
649 \consists "Timing_translator"
650 \consists "Default_bar_line_engraver"
656 \consists "Timing_translator"
657 \consists "Default_bar_line_engraver"
666 \remove "Timing_translator"
667 \remove "Default_bar_line_engraver"
675 The order in which the engravers are specified is the order in
676 which they are called to carry out their processing. Usually the
677 order in which the engravers are specified does not matter, but in
678 a few special cases the order is important, for example where one
679 engraver writes a property and another reads it, or where one
680 engraver creates a grob and another must process it.
682 The following orderings are important:
686 the @code{Bar_engraver} must normally be first,
689 the @code{New_fingering_engraver} must come before the
690 @code{Script_column_engraver},
693 the @code{Timing_translator} must come before the
694 @code{Bar_number_engraver}.
700 @file{ly/engraver-init.ly}.
703 @node Changing context default settings
704 @subsection Changing context default settings
706 @cindex default context properties, changing
707 @cindex context properties, changing defaults
709 Context and grob properties can be changed with @code{\set}
710 and @code{\override} commands, as described in
711 @ref{Modifying properties}. These commands create music events,
712 making the changes take effect at the point in time the music
715 In contrast, this section explains how to change the @emph{default}
716 values of context and grob properties at the time the context is
717 created. There are two ways of doing this. One modifies the default
718 values in all contexts of a particular type, the other modifies the
719 default values in just one particular instance of a context.
722 * Changing all contexts of the same type::
723 * Changing just one specific context::
724 * Order of precedence::
727 @node Changing all contexts of the same type
728 @unnumberedsubsubsec Changing all contexts of the same type
730 @cindex \context in \layout block
734 The context settings which are to be used by default in
735 @code{Score}, @code{Staff}, @code{Voice} and other contexts may be
736 specified in a @code{\context} block within any @code{\layout} block.
737 The @code{\layout} block should be placed within the @code{\score}
738 block to which it is to apply, after the music.
744 [context settings for all Voice contexts]
748 [context settings for all Staff contexts]
753 The following types of settings may be specified:
757 An @code{\override} command, but with the context name omitted
759 @lilypond[quote,verbatim]
762 a4^"Thicker stems" a a a
768 \override Stem #'thickness = #4.0
775 Directly setting a context property
777 @lilypond[quote,verbatim]
780 a4^"Smaller font" a a a
793 A predefined command such as @code{\dynamicUp} or a music
794 expression like @code{\accidentalStyle "dodecaphonic"}
796 @lilypond[quote,verbatim]
799 a4^"Dynamics above" a a a
809 \accidentalStyle "dodecaphonic"
816 A user-defined variable containing a @code{\with} block; for details
817 of the @code{\with} block see
818 @ref{Changing just one specific context}.
820 @lilypond[quote,verbatim]
821 StaffDefaults = \with {
828 a4^"Smaller font" a a a
843 Property-setting commands can be placed in a @code{\layout} block
844 without being enclosed in a @code{\context} block. Such settings
845 are equivalent to including the same property-setting commands at
846 the start of every context of the type specified. If no context
847 is specified @emph{every} bottom-level context is affected, see
848 @ref{Bottom-level contexts - voices}. The syntax of a
849 property-setting command in a @code{\layout} block is the same as
850 the same command written in the music stream.
852 @lilypond[quote,verbatim]
856 a4^"Smaller font" a a a
861 \accidentalStyle "dodecaphonic"
863 \override Voice.Stem #'thickness = #4.0
869 @node Changing just one specific context
870 @unnumberedsubsubsec Changing just one specific context
875 The context properties of just one specific context instance can be
876 changed in a @code{\with} block. All other context instances of the
877 same type retain the default settings built into LilyPond and modified
878 by any @code{\layout} block within scope. The @code{\with} block
879 must be placed immediately after the @code{\new} @var{context-type}
885 [context settings for this context instance only]
891 The following types of settings may be specified:
895 An @code{\override} command, but with the context name omitted
897 @lilypond[quote,verbatim]
902 \override Stem #'thickness = #4.0
906 a4^"Thick stems" a a a
915 Directly setting a context property
917 @lilypond[quote,verbatim]
922 a4^"Default font" a a a
931 a4^"Smaller font" a a a
940 A predefined command such as @code{\dynamicUp}
942 @lilypond[quote,verbatim]
948 a4^"Dynamics below" a a a
954 \with { \accidentalStyle "dodecaphonic" }
960 a4^"Dynamics above" a a a
971 @node Order of precedence
972 @unnumberedsubsubsec Order of precedence
974 The value of a property which applies at a particular time is
975 determined as follows:
979 if an @code{\override} or @code{\set} command in the input stream is
980 in effect that value is used,
983 otherwise the default value taken from a @code{\with} statement
984 on the context initiation statement is used,
987 otherwise the default value taken from the most recent appropriate
988 @code{\context} block in the @code{\layout} blocks is used,
991 otherwise the LilyPond built-in default is used.
996 @rlearning{Modifying context properties}.
999 @ref{Contexts explained},
1000 @ref{Bottom-level contexts - voices},
1001 @ref{The set command},
1002 @ref{The override command},
1003 @ref{The \layout block}.
1006 @node Defining new contexts
1007 @subsection Defining new contexts
1009 @cindex contexts, defining new
1010 @cindex engravers, including in contexts
1025 Specific contexts, like @code{Staff} and @code{Voice}, are made of
1026 simple building blocks. It is possible to create new types of
1027 contexts with different combinations of engraver plug-ins.
1029 The next example shows how to build a different type of
1030 @code{Voice} context from scratch. It will be similar to
1031 @code{Voice}, but only prints centered slash note heads. It can be used
1032 to indicate improvisation in jazz pieces,
1034 @lilypond[quote,ragged-right]
1035 \layout { \context {
1037 \type "Engraver_group"
1038 \consists "Note_heads_engraver"
1039 \consists "Rhythmic_column_engraver"
1040 \consists "Text_engraver"
1041 \consists "Pitch_squash_engraver"
1042 squashedPosition = #0
1043 \override NoteHead #'style = #'slash
1044 \override Stem #'transparent = ##t
1045 \override Flag #'transparent = ##t
1049 \accepts "ImproVoice"
1053 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1054 c4 c^"undress" c_"while playing :)" c }
1060 These settings are defined within a @code{\context} block inside a
1061 @code{\layout} block,
1071 In the following discussion, the example input shown should go in place
1072 of the @dots{} in the previous fragment.
1074 First it is necessary to define a name for the new context:
1080 Since it is similar to the @code{Voice}, we want commands that work
1081 on (existing) @code{Voice}s to remain working. This is achieved by
1082 giving the new context an alias @code{Voice},
1088 The context will print notes and instructive texts, so we need to add
1089 the engravers which provide this functionality,
1092 \consists "Note_heads_engraver"
1093 \consists "Text_engraver"
1096 but we only need this on the center line,
1099 \consists "Pitch_squash_engraver"
1100 squashedPosition = #0
1103 The @rinternals{Pitch_squash_engraver} modifies note heads (created
1104 by @rinternals{Note_heads_engraver}) and sets their vertical
1105 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
1108 The notes look like a slash, and have no stem,
1111 \override NoteHead #'style = #'slash
1112 \override Stem #'transparent = ##t
1113 \override Flag #'transparent = ##t
1116 All these plug-ins have to cooperate, and this is achieved with a
1117 special plug-in, which must be marked with the keyword @code{\type}.
1118 This should always be @code{Engraver_group}.
1121 \type "Engraver_group"
1124 Put together, we get
1129 \type "Engraver_group"
1130 \consists "Note_heads_engraver"
1131 \consists "Text_engraver"
1132 \consists "Pitch_squash_engraver"
1133 squashedPosition = #0
1134 \override NoteHead #'style = #'slash
1135 \override Stem #'transparent = ##t
1136 \override Flag #'transparent = ##t
1142 Contexts form hierarchies. We want to hang the @code{ImproVoice}
1143 under @code{Staff}, just like normal @code{Voice}s. Therefore, we
1144 modify the @code{Staff} definition with the @code{\accepts}
1155 The opposite of @code{\accepts} is @code{\denies},
1156 which is sometimes needed when reusing existing context definitions.
1158 Putting both into a @code{\layout} block, like
1168 \accepts "ImproVoice"
1173 Then the output at the start of this subsection can be entered as
1181 c c_"while playing :)"
1188 @node Context layout order
1189 @subsection Context layout order
1191 @cindex contexts, layout order
1195 Contexts are normally positioned in a system from top to bottom
1196 in the order in which they are encountered in the input file. When
1197 contexts are nested, the outer context will include inner nested
1198 contexts as specified in the input file, provided the inner contexts
1199 are included in the outer context's @qq{accepts} list. Nested
1200 contexts which are not included in the outer context's @qq{accepts}
1201 list will be repositioned below the outer context rather than nested
1204 The @qq{accepts} list of a context can be changed with the
1205 @code{\accepts} and @code{\denies} commands. @code{\accepts} adds a
1206 context to the @qq{accepts} list and @code{\denies} removes a context
1207 from the list. For example, it would not normally be desirable for
1208 chord names to be nested within a @code{Staff} context, so the
1209 @code{ChordNames} context is not included by default in the @qq{accepts}
1210 list of the @code{Staff} context, but if this were to be required it can
1213 @lilypond[verbatim,quote]
1217 \chords { d1:m7 b1:min7.5- }
1222 @lilypond[verbatim,quote]
1226 \chords { d1:m7 b1:min7.5- }
1231 \accepts "ChordNames"
1237 @code{\denies} is mainly used when a new context is being based on
1238 another, but the required nesting differs. For example, the
1239 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1240 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1241 context in the @qq{accepts} list.
1243 Note that a context will be silently created implicitly if a command
1244 is encountered when there is no suitable context available to
1245 contain it. This can give rise to unexpected new staves or scores.
1247 @cindex alignAboveContext
1248 @cindex alignBelowContext
1249 @funindex alignAboveContext
1250 @funindex alignBelowContext
1252 Sometimes a context is required to exist for just a brief period, a
1253 good example being the staff context for an ossia. This is usually
1254 achieved by introducing the context definition at the appropriate
1255 place in parallel with corresponding section of the main music.
1256 By default, the temporary context will be placed below all the
1257 existing contexts. To reposition it above the context called
1258 @qq{main}, it should be defined like this:
1261 @code{\new Staff \with @{ alignAboveContext = #"main" @} }
1264 A similar situation arises when positioning a temporary lyrics
1265 context within a multi-staved layout such as a @code{ChoirStaff},
1266 for example, when adding a second verse to a repeated section.
1267 By default the temporary lyrics context will be placed beneath the
1268 lower staves. By defining the temporary lyrics context with
1269 @code{alignBelowContext} it can be positioned correctly beneath
1270 the (named) lyrics context containing the first verse.
1272 Examples showing this repositioning of temporary contexts can be
1273 found elsewhere --- see @rlearning{Nesting music expressions},
1274 @ref{Modifying single staves} and @ref{Techniques specific to lyrics}.
1278 @rlearning{Nesting music expressions}.
1281 @ref{Modifying single staves},
1282 @ref{Techniques specific to lyrics}.
1285 @rprogram{An extra staff appears}.
1288 @file{ly/engraver-init.ly}.
1291 @node Explaining the Internals Reference
1292 @section Explaining the Internals Reference
1295 * Navigating the program reference::
1296 * Layout interfaces::
1297 * Determining the grob property::
1298 * Naming conventions::
1301 @node Navigating the program reference
1302 @subsection Navigating the program reference
1304 @c TODO remove this (it's in the LM)
1305 @c Replace with more factual directions
1307 Suppose we want to move the fingering indication in the fragment
1310 @lilypond[quote,relative=2,verbatim]
1316 If you visit the documentation on fingering instructions (in
1317 @ref{Fingering instructions}), you will notice:
1322 Internals Reference: @rinternals{Fingering}.
1327 @c outdated info; probably will delete.
1329 This fragment points to two parts of the program reference: a page
1330 on @code{FingeringEvent} and one on @code{Fingering}.
1332 The page on @code{FingeringEvent} describes the properties of the music
1333 expression for the input @w{@code{-2}}. The page contains many links
1334 forward. For example, it says
1337 Accepted by: @rinternals{Fingering_engraver},
1341 That link brings us to the documentation for the Engraver, the
1345 This engraver creates the following layout objects: @rinternals{Fingering}.
1348 In other words, once the @code{FingeringEvent}s are interpreted, the
1349 @code{Fingering_engraver} plug-in will process them.
1353 @c I can't figure out what this is supposed to mean. -gp
1355 The @code{Fingering_engraver} is also listed to create
1356 @rinternals{Fingering} objects,
1358 @c old info? it doesn't make any sense to me with our current docs.
1360 second bit of information listed under @b{See also} in the Notation
1365 The programmer's reference is available as an HTML document. It is
1366 highly recommended that you read it in HTML form, either online or
1367 by downloading the HTML documentation. This section will be much more
1368 difficult to understand if you are using the
1372 Follow the link to @rinternals{Fingering}. At the top of the
1376 Fingering objects are created by: @rinternals{Fingering_engraver} and
1377 @rinternals{New_fingering_engraver}.
1380 By following related links inside the program reference, we can follow the
1381 flow of information within the program:
1385 @item @rinternals{Fingering}:
1386 @rinternals{Fingering} objects are created by:
1387 @rinternals{Fingering_engraver}
1389 @item @rinternals{Fingering_engraver}:
1390 Music types accepted: @rinternals{fingering-event}
1392 @item @rinternals{fingering-event}:
1393 Music event type @code{fingering-event} is in Music expressions named
1394 @rinternals{FingeringEvent}
1397 This path goes against the flow of information in the program: it
1398 starts from the output, and ends at the input event. You could
1399 also start at an input event, and read with the flow of
1400 information, eventually ending up at the output object(s).
1402 The program reference can also be browsed like a normal document. It
1403 contains chapters on
1405 @rinternals{Music definitions},
1408 @code{Music definitions}
1410 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1411 chapter lists all the definitions used and all properties that may be
1415 @node Layout interfaces
1416 @subsection Layout interfaces
1418 @cindex interface, layout
1419 @cindex layout interface
1422 The HTML page that we found in the previous section describes the
1423 layout object called @rinternals{Fingering}. Such an object is a
1424 symbol within the score. It has properties that store numbers (like
1425 thicknesses and directions), but also pointers to related objects. A
1426 layout object is also called a @emph{Grob}, which is short for Graphical
1427 Object. For more details about Grobs, see @rinternals{grob-interface}.
1429 The page for @code{Fingering} lists the definitions for the
1430 @code{Fingering} object. For example, the page says
1433 @code{padding} (dimension, in staff space):
1439 which means that the number will be kept at a distance of at least 0.5
1443 Each layout object may have several functions as a notational or
1444 typographical element. For example, the Fingering object
1445 has the following aspects
1449 Its size is independent of the horizontal spacing, unlike slurs or beams.
1452 It is a piece of text. Granted, it is usually a very short text.
1455 That piece of text is typeset with a font, unlike slurs or beams.
1458 Horizontally, the center of the symbol should be aligned to the
1459 center of the note head.
1462 Vertically, the symbol is placed next to the note and the staff.
1465 The vertical position is also coordinated with other superscript
1466 and subscript symbols.
1469 Each of these aspects is captured in so-called @emph{interface}s,
1470 which are listed on the @rinternals{Fingering} page at the bottom
1473 This object supports the following interfaces:
1474 @rinternals{item-interface},
1475 @rinternals{self-alignment-interface},
1476 @rinternals{side-position-interface}, @rinternals{text-interface},
1477 @rinternals{text-script-interface}, @rinternals{font-interface},
1478 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1481 Clicking any of the links will take you to the page of the respective
1482 object interface. Each interface has a number of properties. Some of
1483 them are not user-serviceable (@q{Internal properties}), but others
1486 We have been talking of @emph{the} @code{Fingering} object, but actually it
1487 does not amount to much. The initialization file (see
1488 @rlearning{Other sources of information})
1489 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1494 (avoid-slur . around)
1495 (slur-padding . 0.2)
1496 (staff-padding . 0.5)
1497 (self-alignment-X . 0)
1498 (self-alignment-Y . 0)
1499 (script-priority . 100)
1500 (stencil . ,ly:text-interface::print)
1501 (direction . ,ly:script-interface::calc-direction)
1502 (font-encoding . fetaText)
1503 (font-size . -5) ; don't overlap when next to heads.
1504 (meta . ((class . Item)
1505 (interfaces . (finger-interface
1507 text-script-interface
1509 side-position-interface
1510 self-alignment-interface
1511 item-interface))))))
1515 As you can see, the @code{Fingering} object is nothing more than a
1516 bunch of variable settings, and the webpage in the Internals Reference
1517 is directly generated from this definition.
1520 @node Determining the grob property
1521 @subsection Determining the grob property
1523 @c TODO remove this (it's in the LM)
1524 @c Replace with more factual directions
1526 Recall that we wanted to change the position of the @b{2} in
1528 @lilypond[quote,relative=2,verbatim]
1534 Since the @b{2} is vertically positioned next to its note, we have to
1535 meddle with the interface associated with this positioning. This is
1536 done using @code{side-position-interface}. The page for this interface
1540 @code{side-position-interface}
1542 Position a victim object (this one) next to other objects (the
1543 support). The property @code{direction} signifies where to put the
1544 victim object relative to the support (left or right, up or down?)
1549 Below this description, the variable @code{padding} is described as
1554 (dimension, in staff space)
1556 Add this much extra space between objects that are next to each other.
1560 By increasing the value of @code{padding}, we can move the
1561 fingering away from the note head. The following command inserts
1562 3 staff spaces of white
1563 between the note and the fingering:
1565 \once \override Voice.Fingering #'padding = #3
1568 Inserting this command before the Fingering object is created,
1569 i.e., before @code{c2}, yields the following result:
1571 @lilypond[quote,relative=2,verbatim]
1572 \once \override Voice.Fingering #'padding = #3
1579 In this case, the context for this tweak is @code{Voice}. This
1580 fact can also be deduced from the program reference, for the page for
1581 the @rinternals{Fingering_engraver} plug-in says
1584 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1588 @node Naming conventions
1589 @subsection Naming conventions
1591 Another thing that is needed, is an overview of the various naming
1595 @item scheme functions: lowercase-with-hyphens (incl. one-word
1597 @item scheme functions: ly:plus-scheme-style
1598 @item music events, music classes and music properties:
1600 @item Grob interfaces: scheme-style
1601 @item backend properties: scheme-style (but X and Y!)
1602 @item contexts (and MusicExpressions and grobs): Capitalized or
1604 @item context properties: lowercaseFollowedByCamelCase
1606 Capitalized_followed_by_lowercase_and_with_underscores
1609 Questions to be answered:
1611 @item Which of these are conventions and which are rules?
1612 @item Which are rules of the underlying language, and which are
1616 @node Modifying properties
1617 @section Modifying properties
1619 @c TODO change the menu and subsection node names to use
1620 @c backslash once the new macro to handle the refs
1621 @c is available. Need to find and change all refs at
1622 @c the same time. -td
1625 * Overview of modifying properties::
1627 * The override command::
1628 * The tweak command::
1629 * set versus override::
1630 * Modifying alists::
1634 @node Overview of modifying properties
1635 @subsection Overview of modifying properties
1637 Each context is responsible for creating certain types of graphical
1638 objects. The settings used for printing these objects are also stored by
1639 context. By changing these settings, the appearance of objects can be
1642 There are two different kinds of properties stored in contexts:
1643 context properties and grob properties. Context properties are
1644 properties that apply to the context as a whole and control
1645 how the context itself is displayed. In contrast, grob properties
1646 apply to specific grob types that will be displayed in the context.
1648 The @code{\set} and @code{\unset} commands are used to change values
1649 for context properties. The @code{\override} and @code{\revert}
1650 commands are used to change values for grob properties.
1653 The syntax for this is
1656 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1659 Here @var{name} is the name of a graphical object, like
1660 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1661 variable of the formatting system (@q{grob property} or @q{layout
1662 property}). The latter is a symbol, so it must be quoted. The
1663 subsection @ref{Modifying properties}, explains what to fill in
1664 for @var{name}, @var{property}, and @var{value}. Here we only
1665 discuss the functionality of this command.
1670 \override Staff.Stem #'thickness = #4.0
1674 makes stems thicker (the default is 1.3, with staff line thickness as a
1675 unit). Since the command specifies @code{Staff} as context, it only
1676 applies to the current staff. Other staves will keep their normal
1677 appearance. Here we see the command in action:
1679 @lilypond[quote,verbatim,relative=2]
1681 \override Staff.Stem #'thickness = #4.0
1687 The @code{\override} command changes the definition of the @code{Stem}
1688 within the current @code{Staff}. After the command is interpreted
1689 all stems are thickened.
1691 Analogous to @code{\set}, the @var{context} argument may be left out,
1692 causing the default context @code{Voice} to be used. Adding
1693 @code{\once} applies the change during one timestep only.
1695 @lilypond[quote,verbatim,relative=2]
1697 \once \override Stem #'thickness = #4.0
1702 The @code{\override} must be done before the object is
1703 started. Therefore, when altering @emph{Spanner} objects such as slurs
1704 or beams, the @code{\override} command must be executed at the moment
1705 when the object is created. In this example,
1707 @lilypond[quote,verbatim,relative=2]
1708 \override Slur #'thickness = #3.0
1710 \override Beam #'beam-thickness = #0.6
1715 the slur is fatter but the beam is not. This is because the command for
1716 @code{Beam} comes after the Beam is started, so it has no effect.
1718 Analogous to @code{\unset}, the @code{\revert} command for a context
1719 undoes an @code{\override} command; like with @code{\unset}, it only
1720 affects settings that were made in the same context. In other words, the
1721 @code{\revert} in the next example does not do anything.
1724 \override Voice.Stem #'thickness = #4.0
1725 \revert Staff.Stem #'thickness
1728 Some tweakable options are called @q{subproperties} and reside inside
1729 properties. To tweak those, use commands of the form
1731 @c leave this as a long long
1733 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1740 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1746 Internals Reference:
1747 @rinternals{Backend},
1748 @rinternals{All layout objects},
1749 @rinternals{OverrideProperty},
1750 @rinternals{RevertProperty},
1751 @rinternals{PropertySet}.
1754 The back-end is not very strict in type-checking object properties.
1755 Cyclic references in Scheme values for properties can cause hangs
1756 or crashes, or both.
1759 @node The set command
1760 @subsection The @code{@bs{}set} command
1764 @cindex changing properties
1766 Each context has a set of @emph{properties}, variables contained
1767 in that context. Context properties are changed with the @code{\set}
1768 command, which has the following syntax:
1771 \set @var{context}.@var{property} = #@var{value}
1774 @var{value} is a Scheme object, which is why it must be preceded by
1775 the @code{#}@tie{}character.
1777 Contexts properties are usually named in
1778 @code{studlyCaps}. They mostly control the translation from
1779 music to notation, e.g. @code{localKeySignature} (for determining
1780 whether to print accidentals), or @code{measurePosition} (for
1781 determining when to print a bar line). Context properties can
1782 change value over time while interpreting a piece of music;
1783 @code{measurePosition} is an obvious example of
1784 this. Context properties are modified with @code{\set}.
1786 For example, multimeasure rests will be combined into a single bar
1787 if the context property @code{skipBars} is set to @code{#t}:
1789 @lilypond[quote,verbatim,relative=2]
1791 \set Score.skipBars = ##t
1795 If the @var{context} argument is left out, then the property will be
1796 set in the current bottom context (typically @code{ChordNames},
1797 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1799 @lilypond[quote,verbatim,relative=2]
1800 \set Score.autoBeaming = ##f
1804 \set autoBeaming = ##t
1812 The change is applied @q{on-the-fly}, during the music, so that the
1813 setting only affects the second group of eighth notes.
1815 Note that the bottom-most context does not always contain the property
1816 that you wish to change -- for example, attempting to set the
1817 @code{skipBars} property of the default bottom context, in this case
1818 @code{Voice}, will have no effect, because skipBars is a property of
1819 the @code{Score} context.
1821 @lilypond[quote,verbatim,relative=2]
1827 Contexts are hierarchical, so if an enclosing context was specified, for
1828 example @code{Staff}, then the change would also apply to all
1829 @code{Voice}s in the current staff.
1833 The @code{\unset} command:
1836 \unset @var{context}.@var{property}
1840 is used to remove the definition of @var{property} from
1841 @var{context}. This command removes
1842 the definition only if it is set in @var{context}.
1843 Properties that have been set in enclosing contexts will
1844 not be altered by an unset in an enclosed context:
1846 @lilypond[quote,verbatim,relative=2]
1847 \set Score.autoBeaming = ##t
1852 \unset Score.autoBeaming
1860 Like @code{\set}, the @var{context} argument does not have to be
1861 specified for a bottom context, so the two statements
1864 \set Voice.autoBeaming = ##t
1865 \set autoBeaming = ##t
1869 are equivalent if the current bottom context is @code{Voice}.
1873 Preceding a @code{\set} command by @code{\once} makes the
1874 setting apply to only a single time-step:
1876 @lilypond[quote,verbatim,relative=2]
1878 \once \set fontSize = #4.7
1883 A full description of all available context properties is in the
1884 internals reference, see
1886 @rinternals{Tunable context properties}.
1889 Translation @expansion{} Tunable context properties.
1893 Internals Reference:
1894 @rinternals{Tunable context properties}.
1896 @cindex grob properties
1897 @cindex properties, grob
1901 @node The override command
1902 @subsection The @code{\override} command
1904 There is a special type of context property: the grob
1905 description. Grob descriptions are named in @code{StudlyCaps}
1906 (starting with capital letters). They contain the
1907 @q{default settings} for a particular kind of grob as an
1908 association list. See @file{scm/define-grobs.scm}
1909 to see the settings for each grob description. Grob descriptions
1910 are modified with @code{\override}.
1912 @code{\override} is actually a shorthand;
1915 \override @var{context}.@var{GrobName} #'@var{property} = #@var{value}
1919 is more or less equivalent to
1921 @c leave this long line -gp
1923 \set @var{context}.@var{GrobName} =
1924 #(cons (cons '@var{property} @var{value})
1925 <previous value of @var{context}.@var{GrobName}>)
1928 The value of @code{context}.@code{GrobName} (the alist) is used to initialize
1929 the properties of individual grobs. Grobs have
1930 properties, named in Scheme style, with
1931 @code{dashed-words}. The values of grob properties change
1932 during the formatting process: formatting basically amounts
1933 to computing properties using callback functions.
1935 For example, we can increase the thickness of a note stem by
1936 overriding the @code{thickness} property of the @code{Stem}
1939 @lilypond[quote,verbatim,relative=2]
1941 \override Voice.Stem #'thickness = #3.0
1945 If no context is specified in an @code{\override}, the bottom
1948 @lilypond[quote,verbatim,relative=2]
1949 { \override Staff.Stem #'thickness = #3.0
1953 \override Stem #'thickness = #0.5
1963 @cindex reverting overrides
1964 @cindex overrides, reverting
1966 The effects of @code{\override} can be undone by @code{\revert}:
1968 @lilypond[quote,verbatim,relative=2]
1970 \override Voice.Stem #'thickness = #3.0
1972 \revert Voice.Stem #'thickness
1976 The effects of @code{\override} and @code{\revert} apply to all
1977 grobs in the affected context from the current time forward:
1979 @lilypond[quote,verbatim,relative=2]
1984 \override Staff.Stem #'thickness = #3.0
1988 \revert Staff.Stem #'thickness
1996 @cindex overriding for only one moment
1998 @code{\once} can be used with @code{\override}
1999 to affect only the current time step:
2001 @lilypond[quote,verbatim,relative=2]
2005 \override Stem #'thickness = #3.0
2009 \once \override Stem #'thickness = #3.0
2018 Commands which change output generally look like
2021 \override Voice.Stem #'thickness = #3.0
2025 To construct this tweak we must determine these bits of information:
2028 @item the context: here @code{Voice}.
2029 @item the layout object: here @code{Stem}.
2030 @item the layout property: here @code{thickness}.
2031 @item a sensible value: here @code{3.0}.
2034 Some tweakable options are called @q{subproperties} and reside inside
2035 properties. To tweak those, use commands in the form
2038 \override Stem #'(details beamed-lengths) = #'(4 4 3)
2041 @cindex internal documentation
2042 @cindex finding graphical objects
2043 @cindex graphical object descriptions
2046 @cindex internal documentation
2048 For many properties, regardless of the data type of the property, setting the
2049 property to false (@code{#f}) will result in turning it off, causing
2050 LilyPond to ignore that property entirely. This is particularly useful for
2051 turning off grob properties which may otherwise be causing problems.
2053 We demonstrate how to glean this information from the notation manual
2054 and the program reference.
2058 Internals Reference:
2059 @rinternals{Backend}
2062 @node The tweak command
2063 @subsection The @code{\tweak} command
2068 Changing grob properties
2069 with @code{\override} causes the changes to apply to all of the
2070 given grobs in the context at the moment the change applies.
2071 Sometimes, however, it is desirable to have changes apply to just
2072 one grob, rather than to all grobs in the affected context. This is
2073 accomplished with the @code{\tweak} command, which has the following
2077 \tweak @var{layout-object} #'@var{grob-property} @var{value}
2080 Specifying @var{layout-object} is optional.
2081 The @code{\tweak} command applies to the music object that immediately
2082 follows @var{value} in the music stream.
2085 In some cases, it is possible to take a short-cut for tuning
2086 graphical objects. For objects that are created directly from
2087 an item in the input file, you can use the @code{\tweak} command.
2090 @lilypond[relative=2,verbatim,quote]
2095 \tweak #'duration-log #1
2098 -\tweak #'padding #8
2104 But the main use of the @code{\tweak} command is to modify just
2105 one of a number of notation elements which start at the same musical
2106 moment, like the notes of a chord, or tuplet brackets which start
2109 The @code{\tweak} command sets a property in the following object
2110 directly, without requiring the grob name or context to be
2111 specified. For this to work, it is necessary for the @code{\tweak}
2112 command to remain immediately adjacent to the object to which it is
2113 to apply after the input file has been converted to a music stream.
2114 This is often not the case, as many additional elements are inserted
2115 into the music stream implicitly. For example, when a note which is
2116 not part of a chord is processed, LilyPond implicitly inserts a
2117 @code{ChordEvent} event before the note, so separating the tweak
2118 from the note. However, if chord symbols are placed round the
2119 tweak and the note, the @code{\tweak} command comes after the
2120 @code{ChordEvent} in the music stream, so remaining adjacent to the
2121 note, and able to modify it.
2125 @lilypond[relative=2,verbatim,quote]
2126 <\tweak #'color #red c>4
2132 @lilypond[relative=2,verbatim,quote]
2133 \tweak #'color #red c4
2138 For an introduction to the syntax and uses of the tweak command
2139 see @rlearning{Tweaking methods}.
2141 When several similar items are placed at the same musical moment,
2142 the @code{\override} command cannot be used to modify just one of
2143 them -- this is where the @code{\tweak} command must be used.
2144 Items which may appear more than once at the same musical moment
2145 include the following:
2147 @c TODO expand to include any further uses of \tweak
2149 @item note heads of notes inside a chord
2150 @item articulation signs on a single note
2151 @item ties between notes in a chord
2152 @item tuplet brackets starting at the same time
2155 @c TODO add examples of these
2157 @cindex chord, modifying one note in
2159 In this example, the color of one note head and the type of another
2160 note head are modified within a single chord:
2162 @lilypond[relative=2,verbatim,quote]
2167 \tweak #'duration-log #1
2172 @code{\tweak} can be used to modify slurs:
2174 @lilypond[verbatim,quote,relative=1]
2175 c-\tweak #'thickness #5 ( d e f)
2179 For the @code{\tweak} command to work, it must
2180 remain immediately adjacent to the object to which it is
2181 to apply after the input file has been converted to a music stream.
2182 Tweaking a whole chord does not do anything since its music event
2183 only acts as a container, and all layout objects are created from events
2184 inside of the @code{EventChord}:
2186 @lilypond[relative=2,verbatim,quote]
2187 \tweak #'color #red c4
2188 \tweak #'color #red <c e>4
2189 <\tweak #'color #red c e>4
2192 The simple @code{\tweak} command cannot be used to modify any object
2193 that is not directly created from the input. In particular
2194 it will not affect stems, automatic
2195 beams or accidentals, since these are generated later by
2196 @code{NoteHead} layout objects rather than by music elements in the
2199 Such indirectly created layout objects can be tweaked using the explicit
2200 form of the @code{\tweak} command:
2202 @lilypond[relative=2,verbatim,quote]
2203 \tweak Stem #'color #red
2204 \tweak Beam #'color #green c8 e
2205 <c e \tweak Accidental #'font-size #-3 ges>4
2208 @code{\tweak} cannot be used to modify clefs or time
2209 signatures, since these become separated from any preceding
2210 @code{\tweak} command in the input stream by the automatic
2211 insertion of extra elements required to specify the context.
2213 Several @code{\tweak} commands may be placed before a
2214 notational element -- all affect it:
2216 @lilypond[verbatim,quote,relative=1]
2218 -\tweak #'style #'dashed-line
2219 -\tweak #'dash-fraction #0.2
2220 -\tweak #'thickness #3
2221 -\tweak #'color #red
2226 The music stream which is generated from a section of an input file,
2227 including any automatically inserted elements, may be examined,
2228 see @rextend{Displaying music expressions}. This may be helpful in
2229 determining what may be modified by a @code{\tweak} command, or
2230 in determining how to adjust the input to make a @code{\tweak}
2235 @rlearning{Tweaking methods}.
2238 @rextend{Displaying music expressions}.
2242 @cindex tweaking control points
2243 @cindex control points, tweaking
2245 The @code{\tweak} command cannot be used to modify the control
2246 points of just one of several ties in a chord, other than the first
2247 one encountered in the input file.
2249 @node set versus override
2250 @subsection @code{\set} vs. @code{\override}
2252 @c TODO -- This section is probably unnecessary now.
2255 We have seen two methods of changing properties: @code{\set} and
2256 @code{\override}. There are actually two different kinds of
2259 @code{fontSize} is a special property: it is equivalent to
2260 entering @code{\override ... #'font-size} for all pertinent
2261 objects. Since this is a common change, the special
2262 property (modified with @code{\set}) was created.
2267 @node Modifying alists
2268 @subsection Modifying alists
2270 Some user-configurable properties are internally represented as
2271 @emph{alists} (association lists), which store pairs of
2272 @emph{keys} and @emph{values}. The structure of an alist is:
2275 '((@var{key1} . @var{value1})
2276 (@var{key2} . @var{value2})
2277 (@var{key3} . @var{value3})
2281 If an alist is a grob property or @code{\paper} variable, its keys
2282 can be modified individually without affecting other keys.
2284 For example, to reduce the space between adjacent staves in a
2285 staff-group, use the @code{staff-staff-spacing} property of the
2286 @code{StaffGrouper} grob. The property is an alist with four
2287 keys: @code{basic-distance}, @code{minimum-distance},
2288 @code{padding}, and @code{stretchability}. The standard settings
2289 for this property are listed in the @qq{Backend} section of the
2290 Internals Reference (see @rinternals{StaffGrouper}):
2293 '((basic-distance . 9)
2294 (minimum-distance . 7)
2296 (stretchability . 5))
2299 One way to bring the staves closer together is by reducing the
2300 value of the @code{basic-distance} key (@code{9}) to match the
2301 value of @code{minimum-distance} (@code{7}). To modify a single
2302 key individually, use a @emph{nested declaration}:
2304 @lilypond[quote,verbatim]
2305 % default space between staves
2307 \new Staff { \clef treble c''1 }
2308 \new Staff { \clef bass c1 }
2311 % reduced space between staves
2312 \new PianoStaff \with {
2313 % this is the nested declaration
2314 \override StaffGrouper #'staff-staff-spacing #'basic-distance = #7
2316 \new Staff { \clef treble c''1 }
2317 \new Staff { \clef bass c1 }
2321 Using a nested declaration will update the specified key (such as
2322 @code{basic-distance} in the above example) without altering any
2323 other keys already set for the same property.
2325 Now suppose we want the staves to be as close as possible without
2326 overlapping. The simplest way to do this is to set all four alist
2327 keys to zero. However, it is not necessary to enter four nested
2328 declarations, one for each key. Instead, the property can be
2329 completely re-defined with one declaration, as an alist:
2331 @lilypond[quote,verbatim]
2332 \new PianoStaff \with {
2333 \override StaffGrouper #'staff-staff-spacing =
2334 #'((basic-distance . 0)
2335 (minimum-distance . 0)
2337 (stretchability . 0))
2339 \new Staff { \clef treble c''1 }
2340 \new Staff { \clef bass c1 }
2344 Note that any keys not explicitly listed in the alist definition
2345 will be reset to their @emph{default-when-unset} values. In the
2346 case of @code{staff-staff-spacing}, any unset key-values would be
2347 reset to zero (except @code{stretchability}, which takes the value
2348 of @code{basic-distance} when unset). Thus the following two
2349 declarations are equivalent:
2352 \override StaffGrouper #'staff-staff-spacing =
2353 #'((basic-distance . 7))
2355 \override StaffGrouper #'staff-staff-spacing =
2356 #'((basic-distance . 7)
2357 (minimum-distance . 0)
2359 (stretchability . 7))
2362 One (possibly unintended) consequence of this is the removal of
2363 any standard settings that are set in an initialization file and
2364 loaded each time an input file is compiled. In the above example,
2365 the standard settings for @code{padding} and
2366 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2367 are reset to their default-when-unset values (zero for both keys).
2368 Defining a property or variable as an alist (of any size) will
2369 always reset all unset key-values to their default-when-unset
2370 values. Unless this is the intended result, it is safer to update
2371 key-values individually with a nested declaration.
2373 @warning{Nested declarations will not work for context property
2374 alists (such as @code{beamExceptions}, @code{keySignature},
2375 @code{timeSignatureSettings}, etc.). These properties can only be
2376 modified by completely re-defining them as alists.}
2379 @node Useful concepts and properties
2380 @section Useful concepts and properties
2385 * Direction and placement::
2386 * Distances and measurements::
2387 * Staff symbol properties::
2389 * Visibility of objects::
2391 * Rotating objects::
2395 @subsection Input modes
2397 The way in which the notation contained within an input file is
2398 interpreted is determined by the current input mode.
2402 This is activated with the @code{\chordmode} command, and causes
2403 input to be interpreted with the syntax of chord notation, see
2404 @ref{Chord notation}. Chords are rendered as notes on a staff.
2406 Chord mode is also activated with the @code{\chords} command.
2407 This also creates a new @code{ChordNames} context and
2408 causes the following input to be interpreted with the syntax of
2409 chord notation and rendered as chord names in the @code{ChordNames}
2410 context, see @ref{Printing chord names}.
2414 This is activated with the @code{\drummode} command, and causes
2415 input to be interpreted with the syntax of drum notation, see
2416 @ref{Basic percussion notation}.
2418 Drum mode is also activated with the @code{\drums} command.
2419 This also creates a new @code{DrumStaff} context and causes the
2420 following input to be interpreted with the syntax of drum notation
2421 and rendered as drum symbols on a drum staff, see @ref{Basic
2422 percussion notation}.
2424 @strong{Figure mode}
2426 This is activated with the @code{\figuremode} command, and causes
2427 input to be interpreted with the syntax of figured bass, see
2428 @ref{Entering figured bass}.
2430 Figure mode is also activated with the @code{\figures} command.
2431 This also creates a new @code{FiguredBass} context and causes the
2432 following input to be interpreted with the figured bass syntax
2433 and rendered as figured bass symbols in the @code{FiguredBass}
2434 context, see @ref{Introduction to figured bass}.
2436 @strong{Fret and tab modes}
2438 There are no special input modes for entering fret and tab symbols.
2440 To create tab diagrams, enter notes or chords in note mode and
2441 render them in a @code{TabStaff} context, see
2442 @ref{Default tablatures}.
2444 To create fret diagrams above a staff, you have two choices.
2445 You can either use the @code{FretBoards} context (see
2446 @ref{Automatic fret diagrams} or you can enter them as a markup
2447 above the notes using the @code{\fret-diagram} command (see
2448 @ref{Fret diagram markups}).
2450 @strong{Lyrics mode}
2452 This is activated with the @code{\lyricmode} command, and causes
2453 input to be interpreted as lyric syllables with optional durations
2454 and associated lyric modifiers, see @ref{Vocal music}.
2456 Lyric mode is also activated with the @code{\addlyrics} command.
2457 This also creates a new @code{Lyrics} context and an implicit
2458 @code{\lyricsto} command which associates the following lyrics
2459 with the preceding music.
2461 @strong{Markup mode}
2463 This is activated with the @code{\markup} command, and causes
2464 input to be interpreted with the syntax of markup, see
2465 @ref{Text markup commands}.
2467 @c silly work-around for texinfo broken-ness
2468 @c (@strong{Note...} causes a spurious cross-reference in Info)
2471 This is the default mode or it may be activated with the
2472 @code{\notemode} command. Input is interpreted as pitches,
2473 durations, markup, etc and typeset as musical notation on a staff.
2475 It is not normally necessary to specify note mode explicitly, but
2476 it may be useful to do so in certain situations, for example if you
2477 are in lyric mode, chord mode or any other mode and want to insert
2478 something that only can be done with note mode syntax.
2480 For example, to indicate dynamic markings for the verses of a
2481 choral pieces it is necessary to enter note mode to interpret
2484 @lilypond[verbatim,relative=2,quote]
2487 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2491 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2498 @node Direction and placement
2499 @subsection Direction and placement
2501 In typesetting music the direction and placement of many items is
2502 a matter of choice. For example, the stems of notes can
2503 be directed up or down; lyrics, dynamics, and other expressive
2504 marks may be placed above or below the staff; text may be aligned
2505 left, right or center; etc. Most of these choices may be left to
2506 be determined automatically by LilyPond, but in some cases it may
2507 be desirable to force a particular direction or placement.
2509 @strong{Articulation direction indicators}
2511 By default some directions are always up or always down (e.g.
2512 dynamics or fermata), while other things can alternate between
2513 up or down based on the stem direction (like slurs or accents).
2515 @c TODO Add table showing these
2517 The default action may be overridden by prefixing the articulation
2518 by a @emph{direction indicator}. Three direction indicators are
2519 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2520 and @code{-} (meaning @qq{use default direction}). The direction
2521 indicator can usually be omitted, in which case @code{-} is assumed,
2522 but a direction indicator is @strong{always} required before
2525 @item @code{\tweak} commands
2526 @item @code{\markup} commands
2527 @item @code{\tag} commands
2528 @item string markups, e.g. -"string"
2529 @item fingering instructions, e.g. @w{@code{-1}}
2530 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2533 Direction indicators affect only the next note:
2535 @lilypond[verbatim,quote,relative=2]
2542 @strong{The direction property}
2544 The position or direction of many layout objects is controlled by the
2545 @code{direction} property.
2547 The value of the @code{direction} property may be set to @code{1},
2548 meaning @qq{up} or @qq{above}, or to @w{@code{-1}}, meaning @qq{down} or
2549 @qq{below}. The symbols @code{UP} and @code{DOWN} may be used instead
2550 of @code{1} and @w{@code{-1}} respectively. The default direction may
2551 be specified by setting @code{direction} to @code{0} or @code{CENTER}.
2552 Alternatively, in many cases predefined commands exist to specify the
2553 direction. These are of the form
2556 @code{\xxxUp}, @code{\xxxDown} or @code{\xxxNeutral}
2560 where @code{\xxxNeutral} means @qq{use the default} direction.
2561 See @rlearning{Within-staff objects}.
2563 In a few cases, arpeggio for example, the value of the @code{direction}
2564 property can specify whether the object is to be placed to the right or
2565 left of the parent. In this case @w{@code{-1}} or @code{LEFT} means
2566 @qq{to the left} and @code{1} or @code{RIGHT} means @qq{to the right}.
2567 @code{0} or @code{CENTER} means @qq{use the default} direction.
2570 These all have side-axis set to #X
2571 AmbitusAccidental - direction has no effect
2573 StanzaNumber - not tried
2574 TrillPitchAccidental - not tried
2575 TrillPitchGroup - not tried
2578 These indications affect all notes until they are canceled.
2580 @lilypond[verbatim,quote,relative=2]
2589 In polyphonic music, it is generally better to specify an explicit
2590 @code{voice} than change an object's direction. For more information.
2591 See @ref{Multiple voices}.
2595 @rlearning{Within-staff objects}.
2598 @ref{Multiple voices}.
2601 @node Distances and measurements
2602 @subsection Distances and measurements
2604 @cindex distances, absolute
2605 @cindex distances, scaled
2612 Distances in LilyPond are of two types: absolute and scaled.
2614 Absolute distances are used for specifying margins, indents, and
2615 other page layout details, and are by default specified in
2616 millimeters. Distances may be specified in other units by
2617 following the quantity by @code{\mm}, @code{\cm},
2618 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2619 an inch). Page layout distances can also be specified in scalable
2620 units (see the following paragraph) by appending
2621 @code{\staff-space} to the quantity. Page layout is described in
2622 detail in @ref{Page layout}.
2624 Scaled distances are always specified in units of the staff-space
2625 or, rarely, the half staff-space. The staff-space is the distance
2626 between two adjacent staff lines. The default value can be changed
2627 globally by setting the global staff size, or it can be overridden
2628 locally by changing the @code{staff-space} property of
2629 @code{StaffSymbol}. Scaled distances automatically scale with any
2630 change to the either the global staff size or the
2631 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2632 automatically only with changes to the global staff size.
2633 The global staff size thus enables the overall size of a rendered
2634 score to be easily varied. For the methods of setting the global
2635 staff size see @ref{Setting the staff size}.
2639 If just a section of a score needs to be rendered to a different
2640 scale, for example an ossia section or a footnote, the global staff
2641 size cannot simply be changed as this would affect the entire score.
2642 In such cases the change in size is made by overriding both the
2643 @code{staff-space} property of @code{StaffSymbol} and the size of
2644 the fonts. A Scheme function, @code{magstep}, is available to
2645 convert from a font size change to the equivalent change in
2646 @code{staff-space}. For an explanation and an example of its use,
2647 see @rlearning{Length and thickness of objects}.
2651 @rlearning{Length and thickness of objects}.
2655 @ref{Setting the staff size}.
2658 @node Staff symbol properties
2659 @subsection Staff symbol properties
2661 @cindex adjusting staff symbol
2662 @cindex drawing staff symbol
2663 @cindex staff symbol, setting of
2665 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2666 @c Need to think of uses for these properties. Eg 'line-positions
2667 @c is used in a snippet to thicken centre line.
2668 @c If retained, add @ref to here in 1.6.2 -td
2670 The vertical position of staff lines and the number of staff lines
2671 can be defined at the same time. As the following example shows,
2672 note positions are not influenced by the staff line positions.
2674 @warning{The @code{'line-positions} property overrides the
2675 @code{'line-count} property. The number of staff lines is
2676 implicitly defined by the number of elements in the list of values
2677 for @code{'line-positions}.}
2679 @lilypond[verbatim,quote,relative=1]
2681 \override StaffSymbol #'line-positions = #'(7 3 0 -4 -6 -7)
2686 The width of a staff can be modified. The units are staff
2687 spaces. The spacing of objects inside the staff is not affected by
2690 @lilypond[verbatim,quote,relative=1]
2692 \override StaffSymbol #'width = #23
2699 @subsection Spanners
2701 Many objects of musical notation extend over several notes or even
2702 several bars. Examples are slurs, beams, tuplet brackets, volta
2703 repeat brackets, crescendi, trills, and glissandi. Such objects
2704 are collectively called @qq{spanners}, and have special properties to control
2705 their appearance and behaviour. Some of these properties are common
2706 to all spanners; others are restricted to a sub-set of the spanners.
2708 All spanners support the @code{spanner-interface}. A few, essentially
2709 those that draw a straight line between the two objects, support in
2710 addition the @code{line-spanner-interface}.
2712 @unnumberedsubsubsec Using the @code{spanner-interface}
2714 This interface provides two properties that apply to several spanners.
2716 @strong{@i{The @code{minimum-length} property}}
2718 The minimum length of the spanner is specified by the
2719 @code{minimum-length} property. Increasing this usually has the
2720 necessary effect of increasing the spacing of the notes between the
2721 two end points. However, this override has no effect on
2722 many spanners, as their length is determined by other considerations.
2723 A few examples where it is effective are shown below.
2733 Works as long as callback is made:
2737 Works not at all for:
2746 @lilypond[verbatim,quote,relative=2]
2749 % increase the length of the tie
2750 -\tweak #'minimum-length #5
2754 @lilypond[verbatim,quote,relative=2]
2756 \compressFullBarRests
2758 % increase the length of the rest bar
2759 \once \override MultiMeasureRest #'minimum-length = #20
2764 @lilypond[verbatim,quote,relative=2]
2766 % increase the length of the hairpin
2767 \override Hairpin #'minimum-length = #20
2771 This override can also be used to increase the length of slurs and
2774 @lilypond[verbatim,quote,relative=2]
2777 -\tweak #'minimum-length #5
2782 -\tweak #'minimum-length #5
2786 For some layout objects, the @code{minimum-length} property becomes
2787 effective only if the @code{set-spacing-rods} procedure is called
2788 explicitly. To do this, the @code{springs-and-rods} property should
2789 be set to @code{ly:spanner::set-spacing-rods}. For example,
2790 the minimum length of a glissando has no effect unless the
2791 @code{springs-and-rods} property is set:
2793 @lilypond[verbatim,quote,relative=1]
2797 % not effective alone
2798 \once \override Glissando #'minimum-length = #20
2801 % effective only when both overrides are present
2802 \once \override Glissando #'minimum-length = #20
2803 \once \override Glissando #'springs-and-rods = #ly:spanner::set-spacing-rods
2807 The same is true of the @code{Beam} object:
2809 @lilypond[verbatim,quote,relative=1]
2810 % not effective alone
2811 \once \override Beam #'minimum-length = #20
2814 % effective only when both overrides are present
2815 \once \override Beam #'minimum-length = #20
2816 \once \override Beam #'springs-and-rods = #ly:spanner::set-spacing-rods
2820 @strong{@i{The @code{to-barline} property}}
2822 The second useful property of the @code{spanner-interface} is
2823 @code{to-barline}. By default this is true, causing hairpins and
2824 other spanners which are terminated on the first note of a measure to
2825 end instead on the immediately preceding bar line. If set to false,
2826 the spanner will extend beyond the bar line and end on the note
2829 @lilypond[verbatim,quote,relative=2]
2830 a \< a a a a \! a a a \break
2831 \override Hairpin #'to-barline = ##f
2832 a \< a a a a \! a a a
2835 This property is not effective for all spanners. For example,
2836 setting it to @code{#t} has no effect on slurs or phrasing slurs
2837 or on other spanners for which terminating on the bar line would
2840 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2842 Objects which support the @code{line-spanner-interface} include
2845 @item @code{DynamicTextSpanner}
2846 @item @code{Glissando}
2847 @item @code{TextSpanner}
2848 @item @code{TrillSpanner}
2849 @item @code{VoiceFollower}
2852 The routine responsible for drawing the stencils for these spanners is
2853 @code{ly:line-interface::print}. This routine determines the
2854 exact location of the two end points and draws a line
2855 between them, in the style requested. The locations of the two
2856 end points of the spanner are computed on-the-fly, but it is
2857 possible to override their Y-coordinates. The
2858 properties which need to be specified are nested
2859 two levels down within the property hierarchy, but the syntax of
2860 the @code{\override} command is quite simple:
2862 @lilypond[relative=2,quote,verbatim]
2864 \once \override Glissando #'(bound-details left Y) = #3
2865 \once \override Glissando #'(bound-details right Y) = #-2
2869 The units for the @code{Y} property are @code{staff-space}s,
2870 with the center line of the staff being the zero point.
2871 For the glissando, this is the value for @code{Y} at the
2872 X-coordinate corresponding to the center point of each note head,
2873 if the line is imagined to be extended to there.
2875 If @code{Y} is not set, the value is computed from the vertical
2876 position of the corresponding attachment point of the spanner.
2878 In case of a line break, the values for the end points are
2879 specified by the @code{left-broken} and @code{right-broken}
2880 sub-lists of @code{bound-details}. For example:
2882 @lilypond[relative=2,ragged-right,verbatim,quote]
2883 \override Glissando #'breakable = ##t
2884 \override Glissando #'(bound-details right-broken Y) = #-3
2885 c1 \glissando \break
2890 A number of further properties of the @code{left} and
2891 @code{right} sub-lists of the @code{bound-details} property
2892 may be modified in the same way as @code{Y}:
2896 This sets the Y-coordinate of the end point, in @code{staff-space}s
2897 offset from the staff center line. By default, it is the center of
2898 the bound object, so a glissando points to the vertical center of
2901 For horizontal spanners, such as text spanners and trill spanners,
2902 it is hardcoded to 0.
2905 This determines where the line starts and ends in the X-direction,
2906 relative to the bound object. So, a value of @w{@code{-1}} (or
2907 @code{LEFT}) makes the line start/end at the left side of the note
2908 head it is attached to.
2911 This is the absolute X-coordinate of the end point. It is usually
2912 computed on the fly, and overriding it has little useful effect.
2915 Line spanners may have symbols at the beginning or end, which is
2916 contained in this sub-property. This is for internal use; it is
2917 recommended that @code{text} be used instead.
2920 This is a markup that is evaluated to yield the stencil. It is used
2921 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
2923 @lilypond[quote,ragged-right,relative=2,verbatim]
2924 \override TextSpanner #'(bound-details left text)
2925 = \markup { \small \bold Slower }
2926 c2\startTextSpan b c a\stopTextSpan
2929 @item stencil-align-dir-y
2930 @item stencil-offset
2931 Without setting one of these, the stencil is simply put at the
2932 end-point, centered on the line, as defined by the @code{X} and
2933 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
2934 or @code{stencil-offset} will move the symbol at the edge vertically
2935 relative to the end point of the line:
2937 @lilypond[relative=1,quote,verbatim]
2938 \override TextSpanner
2939 #'(bound-details left stencil-align-dir-y) = #-2
2940 \override TextSpanner
2941 #'(bound-details right stencil-align-dir-y) = #UP
2943 \override TextSpanner
2944 #'(bound-details left text) = #"ggg"
2945 \override TextSpanner
2946 #'(bound-details right text) = #"hhh"
2947 c4^\startTextSpan c c c \stopTextSpan
2950 Note that negative values move the text @emph{up}, contrary to the
2951 effect that might be expected, as a value of @w{@code{-1}} or
2952 @code{DOWN} means align the @emph{bottom} edge of the text with
2953 the spanner line. A value of @code{1} or @code{UP} aligns
2954 the top edge of the text with the spanner line.
2957 Setting this sub-property to @code{#t} produces an arrowhead at the
2961 This sub-property controls the space between the specified
2962 end point of the line and the actual end. Without padding, a
2963 glissando would start and end in the center of each note head.
2967 The music function @code{\endSpanners} terminates the spanner
2968 which starts on the immediately following note prematurely. It
2969 is terminated after exactly one note, or at the following bar line
2970 if @code{to-barline} is true and a bar line occurs before the next
2973 @lilypond[verbatim,quote,ragged-right,relative=2]
2975 c2 \startTextSpan c2 c2
2980 When using @code{\endSpanners} it is not necessary to close
2981 \startTextSpan with \stopTextSpan, nor is it necessary to close
2982 hairpins with @code{\!}.
2985 Internals Reference:
2986 @rinternals{TextSpanner},
2987 @rinternals{Glissando},
2988 @rinternals{VoiceFollower},
2989 @rinternals{TrillSpanner},
2990 @rinternals{line-spanner-interface}.
2993 @node Visibility of objects
2994 @subsection Visibility of objects
2996 @cindex objects, visibility of
2997 @cindex grobs, visibility of
2998 @cindex visibility of objects
3000 There are four main ways in which the visibility of layout objects
3001 can be controlled: their stencil can be removed, they can be made
3002 transparent, they can be colored white, or their
3003 @code{break-visibility} property can be overridden. The first
3004 three apply to all layout objects; the last to just a few -- the
3005 @emph{breakable} objects. The Learning Manual introduces these
3006 four techniques, see @rlearning{Visibility and color of objects}.
3008 There are also a few other techniques which are specific to
3009 certain layout objects. These are covered under Special
3013 * Removing the stencil::
3014 * Making objects transparent::
3015 * Painting objects white::
3016 * Using break-visibility::
3017 * Special considerations::
3021 @node Removing the stencil
3022 @unnumberedsubsubsec Removing the stencil
3024 @cindex stencil, removing
3026 Every layout object has a stencil property. By default this is set
3027 to the specific function which draws that object. If this property
3028 is overridden to @code{#f} no function will be called and the object
3029 will not be drawn. The default action can be recovered with
3032 @lilypond[quote,verbatim,relative=1]
3034 \override Score.BarLine #'stencil = ##f
3036 \revert Score.BarLine #'stencil
3040 @node Making objects transparent
3041 @unnumberedsubsubsec Making objects transparent
3043 @cindex transparent, making objects
3045 Every layout object has a transparent property which by default is
3046 set to @code{#f}. If set to @code{#t} the object still occupies
3047 space but is made invisible.
3049 @lilypond[quote,verbatim,relative=2]
3051 \once \override NoteHead #'transparent = ##t
3055 @node Painting objects white
3056 @unnumberedsubsubsec Painting objects white
3058 @cindex objects, coloring
3059 @cindex coloring objects
3061 @cindex printing order
3062 @cindex overwriting objects
3063 @cindex objects, overwriting
3064 @cindex grobs, overwriting
3066 Every layout object has a color property which by default is set
3067 to @code{black}. If this is overridden to @code{white} the object
3068 will be indistinguishable from the white background. However,
3069 if the object crosses other objects the color of the crossing
3070 points will be determined by the order in which they are drawn,
3071 and this may leave a ghostly image of the white object, as shown
3074 @lilypond[quote,verbatim,relative=2]
3075 \override Staff.Clef #'color = #white
3079 This may be avoided by changing the order of printing the objects.
3080 All layout objects have a @code{layer} property which should be set
3081 to an integer. Objects with the lowest value of @code{layer} are
3082 drawn first, then objects with progressively higher values are drawn,
3083 so objects with higher values overwrite objects with lower values.
3084 By default most objects are assigned a @code{layer} value of
3085 @code{1}, although a few objects, including @code{StaffSymbol} and
3086 @code{BarLine}, are assigned a value of @code{0}. The order of
3087 printing objects with the same value of @code{layer} is indeterminate.
3089 In the example above the white clef, with a default @code{layer}
3090 value of @code{1}, is drawn after the staff lines (default
3091 @code{layer} value @code{0}), so overwriting them. To change this,
3092 the @code{Clef} object must be given in a lower value of
3093 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
3095 @lilypond[quote,verbatim,relative=2]
3096 \override Staff.Clef #'color = #white
3097 \override Staff.Clef #'layer = #-1
3101 @node Using break-visibility
3102 @unnumberedsubsubsec Using break-visibility
3104 @c TODO Add making other objects breakable
3106 @cindex break-visibility
3108 Most layout objects are printed only once, but some like
3109 bar lines, clefs, time signatures and key signatures, may need
3110 to be printed twice when a line break occurs -- once at the end
3111 of the line and again at the start of the next line. Such
3112 objects are called @emph{breakable}, and have a property, the
3113 @code{break-visibility} property to control their visibility
3114 at the three positions in which they may appear -- at the
3115 start of a line, within a line if they are changed, and at the
3116 end of a line if a change takes place there.
3118 For example, the time signature
3119 by default will be printed at the start of the first line, but
3120 nowhere else unless it changes, when it will be printed at the
3121 point at which the change occurs. If this change occurs at the
3122 end of a line the new time signature will be printed at the start
3123 of the next line and a cautionary time signature will be printed
3124 at the end of the previous line as well.
3126 This behaviour is controlled by the @code{break-visibility}
3127 property, which is explained in
3128 @c Leave this ref on a newline - formats incorrectly otherwise -td
3129 @rlearning{Visibility and color of objects}. This property takes
3130 a vector of three booleans which, in order, determine whether the
3131 object is printed at the end of, within the body of, or at the
3132 beginning of a line. Or to be more precise, before a line break,
3133 where there is no line break, or after a line break.
3135 Alternatively, these eight combinations may be specified
3136 by pre-defined functions, defined in @file{scm/output-lib.scm},
3137 where the last three columns indicate whether the layout objects
3138 will be visible in the positions shown at the head of the columns:
3140 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {Before} {At no} {After}
3141 @headitem Function @tab Vector @tab Before @tab At no @tab After
3142 @headitem form @tab form @tab break @tab break @tab break
3144 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
3145 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
3146 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
3147 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
3148 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
3149 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
3150 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
3151 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
3154 The default settings of @code{break-visibility} depend on the
3155 layout object. The following table shows all the layout objects
3156 of interest which are affected by @code{break-visibility} and the
3157 default setting of this property:
3159 @multitable @columnfractions .3 .3 .4
3161 @headitem Layout object @tab Usual context @tab Default setting
3163 @c omit Ambitus as it appears not to be affected by break-visibility -td
3164 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
3165 @item @code{BarLine} @tab @code{Score} @tab calculated
3166 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
3167 @c omit the following item until it can be explained -td
3168 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
3169 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3170 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
3171 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
3172 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3173 @c omit KeyCancellation until it can be explained -td
3174 @c @item @code{KeyCancellation} @tab ?? @tab @code{begin-of-line-invisible}
3175 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
3176 @c omit LeftEdge until it can be explained -td
3177 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
3178 @item @code{OctavateEight} @tab @code{Staff} @tab @code{begin-of-line-visible}
3179 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
3180 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
3184 The example below shows the use of the vector form to control the
3185 visibility of bar lines:
3187 @lilypond[quote,verbatim,relative=1,ragged-right]
3190 % Remove bar line at the end of the current line
3191 \once \override Score.BarLine #'break-visibility = #'#(#f #t #t)
3197 Although all three components of the vector used to override
3198 @code{break-visibility} must be present, not all of them are
3199 effective with every layout object, and some combinations may
3200 even give errors. The following limitations apply:
3203 @item Bar lines cannot be printed at start of line.
3204 @item A bar number cannot be printed at the start of the first
3205 line unless it is set to be different from 1.
3206 @item Clef -- see below
3207 @item Double percent repeats are either all printed or all
3208 suppressed. Use begin-of line-invisible to print and
3209 all-invisible to suppress.
3210 @item Key signature -- see below
3211 @item OctavateEight -- see below
3214 @node Special considerations
3215 @unnumberedsubsubsec Special considerations
3217 @strong{@emph{Visibility following explicit changes}}
3219 @cindex key signature, visibility following explicit change
3220 @cindex explicitKeySignatureVisibility
3221 @cindex clef, visibility following explicit change
3222 @cindex explicitClefVisibility
3224 The @code{break-visibility} property controls the visibility of
3225 key signatures and changes of clef only at the start of lines,
3226 i.e. after a break. It has no effect on the visibility of the
3227 key signature or clef following an explicit key change or an
3228 explicit clef change within or at the end of a line. In the
3229 following example the key signature following the explicit change
3230 to B-flat major is still visible, even though @code{all-invisible}
3233 @lilypond[quote,verbatim,relative=1,ragged-right]
3236 % Try to remove all key signatures
3237 \override Staff.KeySignature #'break-visibility = #all-invisible
3245 The visibility of such explicit key signature and clef changes is
3246 controlled by the @code{explicitKeySignatureVisibility} and
3247 @code{explicitClefVisibility} properties. These are the equivalent
3248 of the @code{break-visibility} property and both take a vector of
3249 three booleans or the predefined functions listed above, exactly like
3250 @code{break-visibility}. Both are properties of the Staff context,
3251 not the layout objects themselves, and so they are set using the
3252 @code{\set} command. Both are set by default to @code{all-visible}.
3253 These properties control only the visibility of key signatures and
3254 clefs resulting from explicit changes and do not affect key
3255 signatures and clefs at the beginning of lines;
3256 @code{break-visibility} must still be overridden in the appropriate
3257 object to remove these.
3259 @lilypond[quote,verbatim,relative=1,ragged-right]
3262 \set Staff.explicitKeySignatureVisibility = #all-invisible
3263 \override Staff.KeySignature #'break-visibility = #all-invisible
3270 @strong{@emph{Visibility of cautionary accidentals}}
3272 To remove the cautionary accidentals printed at an explicit key
3273 change, set the Staff context property @code{printKeyCancellation}
3276 @lilypond[quote,verbatim,relative=1,ragged-right]
3279 \set Staff.explicitKeySignatureVisibility = #all-invisible
3280 \set Staff.printKeyCancellation = ##f
3281 \override Staff.KeySignature #'break-visibility = #all-invisible
3288 With these overrides only the accidentals before the notes remain
3289 to indicate the change of key.
3291 @c TODO Add visibility of cautionary accidentals before notes
3293 @strong{@emph{Automatic bars}}
3295 @cindex automaticBars
3296 @cindex bar lines, suppressing
3298 As a special case, the printing of bar lines can also be turned off
3299 by setting the @code{automaticBars} property in the Score context.
3300 If set to @code{#f}, bar lines will not be printed automatically;
3301 they must be explicitly created with a @code{\bar} command. Unlike
3302 the @code{\cadenzaOn} predefined command, measures are still counted.
3303 Bar generation will resume according to that count if this property
3304 is later set to @code{#t}. When set to @code{#f}, line breaks can
3305 occur only at explicit @code{\bar} commands.
3309 @strong{@emph{Octavated clefs}}
3311 @cindex octavated clefs, visibility of
3312 @cindex visibility of octavated clefs
3313 @cindex clefs, visibility of octavation
3315 The small octavation symbol on octavated clefs is produced by the
3316 @code{OctavateEight} layout object. Its visibility is automatically
3317 inherited from the @code{Clef} object, so it is not necessary to apply
3318 any required @code{break-visibility} overrides to the @code{OctavateEight}
3319 layout objects to suppress octavation symbols for invisible clefs.
3321 For explicit clef changes, the @code{explicitClefVisibility}
3322 property controls both the clef symbol and any octavation symbol
3327 @rlearning{Visibility and color of objects}.
3331 @subsection Line styles
3333 Some performance indications, e.g., @i{rallentando} and
3334 @i{accelerando} and @i{trills} are written as text and are
3335 extended over many measures with lines, sometimes dotted or wavy.
3337 These all use the same routines as the glissando for drawing the
3338 texts and the lines, and tuning their behavior is therefore also
3339 done in the same way. It is done with a spanner, and the routine
3340 responsible for drawing the spanners is
3341 @code{ly:line-interface::print}. This routine determines the
3342 exact location of the two @i{span points} and draws a line
3343 between them, in the style requested.
3345 Here is an example showing the different line styles available,
3346 and how to tune them.
3348 @lilypond[relative=2,ragged-right,verbatim,quote]
3350 \once \override Glissando #'style = #'dashed-line
3352 \override Glissando #'style = #'dotted-line
3354 \override Glissando #'style = #'zigzag
3356 \override Glissando #'style = #'trill
3360 The locations of the end-points of the spanner are computed
3361 on-the-fly for every graphic object, but it is possible to
3365 @lilypond[relative=2,ragged-right,verbatim,quote]
3367 \once \override Glissando #'(bound-details right Y) = #-2
3371 The value for @code{Y} is set to @w{@code{-2}} for the right end
3372 point. The left side may be similarly adjusted by specifying
3373 @code{left} instead of @code{right}.
3375 If @code{Y} is not set, the value is computed from the vertical
3376 position of the left and right attachment points of the spanner.
3378 Other adjustments of spanners are possible, for details, see
3381 @node Rotating objects
3382 @subsection Rotating objects
3384 Both layout objects and elements of markup text can be rotated by
3385 any angle about any point, but the method of doing so differs.
3388 * Rotating layout objects::
3392 @node Rotating layout objects
3393 @unnumberedsubsubsec Rotating layout objects
3395 @cindex rotating objects
3396 @cindex objects, rotating
3398 All layout objects which support the @code{grob-interface} can be
3399 rotated by setting their @code{rotation} property. This takes a
3400 list of three items: the angle of rotation counter-clockwise,
3401 and the x and y coordinates of the point relative to the object's
3402 reference point about which the rotation is to be performed. The
3403 angle of rotation is specified in degrees and the coordinates in
3406 The angle of rotation and the coordinates of the rotation point must
3407 be determined by trial and error.
3409 @cindex hairpins, angled
3410 @cindex angled hairpins
3412 There are only a few situations where the rotation of layout
3413 objects is useful; the following example shows one situation where
3416 @lilypond[quote,verbatim,relative=1]
3418 \override Hairpin #'rotation = #'(20 -1 0)
3422 @node Rotating markup
3423 @unnumberedsubsubsec Rotating markup
3425 All markup text can be rotated to lie at any angle by prefixing it
3426 with the @code{\rotate} command. The command takes two arguments:
3427 the angle of rotation in degrees counter-clockwise and the text to
3428 be rotated. The extents of the text are not rotated: they take
3429 their values from the extremes of the x and y coordinates of the
3430 rotated text. In the following example the
3431 @code{outside-staff-priority} property for text is set to @code{#f}
3432 to disable the automatic collision avoidance, which would push some
3433 of the text too high.
3435 @lilypond[quote,verbatim,relative=1]
3436 \override TextScript #'outside-staff-priority = ##f
3437 g4^\markup { \rotate #30 "a G" }
3438 b^\markup { \rotate #30 "a B" }
3439 des^\markup { \rotate #30 "a D-Flat" }
3440 fis^\markup { \rotate #30 "an F-Sharp" }
3443 @node Advanced tweaks
3444 @section Advanced tweaks
3446 This section discusses various approaches to fine tuning the
3447 appearance of the printed score.
3450 * Aligning objects::
3451 * Vertical grouping of grobs::
3452 * Modifying stencils::
3453 * Modifying shapes::
3454 * Unpure-pure containers::
3459 @rlearning{Tweaking output},
3460 @rlearning{Other sources of information}.
3463 @ref{Explaining the Internals Reference},
3464 @ref{Modifying properties}.
3467 @rextend{Interfaces for programmers}.
3470 @file{scm/define-grobs.scm}.
3473 @rlsr{Tweaks and overrides}.
3475 Internals Reference:
3476 @rinternals{All layout objects}.
3479 @node Aligning objects
3480 @subsection Aligning objects
3482 Graphical objects which support the @code{self-alignment-interface}
3483 and/or the @code{side-position-interface} can be aligned to a previously
3484 placed object in a variety of ways. For a list of these objects, see
3485 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3487 All graphical objects have a reference point, a horizontal extent and a
3488 vertical extent. The horizontal extent is a pair of numbers
3489 giving the displacements from the reference point of the left and
3490 right edges, displacements to the left being negative. The vertical
3491 extent is a pair of numbers giving the displacement from the reference
3492 point to the bottom and top edges, displacements down being negative.
3494 An object's position on a staff is given by the values of the
3495 @code{X-offset} and @code{Y-offset} properties. The value of
3496 @code{X-offset} gives the displacement from the X coordinate of
3497 the reference point of the parent object, and the value of
3498 @code{Y-offset} gives the displacement from the center line of the
3499 staff. The values of @code{X-offset} and @code{Y-offset} may
3500 be set directly or may be set to be calculated by procedures in order
3501 to achieve alignment with the parent object.
3503 @warning{Many objects have special positioning considerations which
3504 cause any setting of @code{X-offset} or @code{Y-offset} to be
3505 ignored or modified, even though the object supports the
3506 @code{self-alignment-interface}. Overriding the @code{X-offset}
3507 or @code{Y-offset} properties to a fixed value causes the respective
3508 @code{self-alignment} property to be disregarded.}
3510 For example, an accidental can be repositioned vertically by setting
3511 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3513 Rehearsal marks may be aligned with breakable objects such as bar
3514 lines, clef symbols, time signature symbols and key signatures. There
3515 are special properties to be found in the @code{break-aligned-interface}
3516 for positioning rehearsal marks on such objects.
3520 @ref{Using the break-alignable-interface}.
3523 @rextend{Callback functions}.
3526 * Setting X-offset and Y-offset directly::
3527 * Using the side-position-interface::
3528 * Using the self-alignment-interface::
3529 * Using the break-alignable-interface::
3532 @node Setting X-offset and Y-offset directly
3533 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3535 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3536 properties of many objects. The following example shows three
3537 notes with the default fingering position and the positions with @code{X-offset}
3538 and @code{Y-offset} modified.
3540 @lilypond[verbatim,quote,relative=2]
3543 -\tweak #'X-offset #0
3544 -\tweak #'Y-offset #0
3547 -\tweak #'X-offset #-1
3548 -\tweak #'Y-offset #1
3554 @node Using the side-position-interface
3555 @unnumberedsubsubsec Using the @code{side-position-interface}
3557 An object which supports the @code{side-position-interface} can be
3558 placed next to its parent object so that
3559 the specified edges of the two objects touch. The object may be
3560 placed above, below, to the right or to the left of the parent.
3561 The parent cannot be specified; it is determined by the order of
3562 elements in the input stream. Most objects have the associated
3563 note head as their parent.
3565 The values of the @code{side-axis} and @code{direction} properties
3566 determine where the object is to be placed, as follows:
3568 @c TODO add an example of each to the table
3570 @multitable @columnfractions .3 .3 .3
3571 @headitem @code{side-axis} @tab @code{direction} @tab
3572 @headitem property @tab property @tab Placement
3574 @item @code{0} @tab @code{-1} @tab left
3575 @item @code{0} @tab @code{1} @tab right
3576 @item @code{1} @tab @code{-1} @tab below
3577 @item @code{1} @tab @code{1} @tab above
3581 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3582 the procedure @code{ly:side-position-interface::x-aligned-side}.
3583 This procedure will return the correct value of @code{X-offset} to
3584 place the object to the left or right side of the parent according
3585 to value of @code{direction}.
3587 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3588 the procedure @code{ly:side-position-interface::y-aligned-side}.
3589 This procedure will return the correct value of @code{Y-offset} to
3590 place the object to the top or bottom of the parent according
3591 to value of @code{direction}.
3593 @c TODO Add examples
3595 @node Using the self-alignment-interface
3596 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3598 @emph{Self-aligning objects horizontally}
3600 The horizontal alignment of an object which supports the
3601 @code{self-alignment-interface} is controlled by the value of
3602 the @code{self-alignment-X} property, provided the object's
3603 @code{X-offset} property is set to
3604 @code{ly:self-alignment-interface::x-aligned-on-self}.
3605 @code{self-alignment-X} may be given any
3606 real value, in units of half the total X extent of the
3607 object. Negative values move the object to the right, positive
3608 to the left. A value of @code{0} centers the object on the
3609 reference point of its parent, a value of @w{@code{-1}} aligns the
3610 left edge of the object on the reference point of its parent,
3611 and a value of @code{1} aligns the right edge of the object on the
3612 reference point of its parent. The symbols @code{LEFT},
3613 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3614 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3616 Normally the @code{\override} command would be used to modify the
3617 value of @code{self-alignment-X}, but the @code{\tweak} command
3618 can be used to separately align several annotations on a single
3621 @lilypond[quote,verbatim,relative=1]
3623 -\tweak #'self-alignment-X #-1
3625 -\tweak #'self-alignment-X #0
3627 -\tweak #'self-alignment-X #RIGHT
3629 -\tweak #'self-alignment-X #-2.5
3630 ^"aligned further to the right"
3633 @emph{Self-aligning objects vertically}
3635 Objects may be aligned vertically in an analogous way to aligning
3636 them horizontally if the @code{Y-offset} property is set to
3637 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3638 other mechanisms are often involved in vertical alignment: the
3639 value of @code{Y-offset} is just one variable taken into account.
3640 This may make adjusting the value of some objects tricky.
3641 The units are just half the vertical extent of the object, which
3642 is usually quite small, so quite large numbers may be required.
3643 A value of @w{@code{-1}} aligns the lower edge of the object with
3644 the reference point of the parent object, a value of @code{0}
3645 aligns the center of the object with the reference point of the
3646 parent, and a value of @code{1} aligns the top edge of the object
3647 with the reference point of the parent. The symbols @code{DOWN},
3648 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3649 @code{0}, and @code{1}, respectively.
3651 @emph{Self-aligning objects in both directions}
3653 By setting both @code{X-offset} and @code{Y-offset}, an object may
3654 be aligned in both directions simultaneously.
3656 The following example shows how to adjust a fingering mark so
3657 that it nestles close to the note head.
3659 @lilypond[quote,verbatim,relative=2]
3661 -\tweak #'self-alignment-X #0.5 % move horizontally left
3662 -\tweak #'Y-offset #ly:self-alignment-interface::y-aligned-on-self
3663 -\tweak #'self-alignment-Y #-1 % move vertically up
3668 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3670 @c Cannot document as they do not seem to operate consistently on all objects -td
3671 @c TODO investigate further
3673 The @code{aligned-on-parent} procedures are used in the same way
3674 as the @code{aligned-on-self} procedures, they difference being
3675 that they permit an object to be aligned with the @emph{edges} of
3676 the parent rather than the parent's reference point. The following
3677 example shows the difference:
3681 @lilypond[verbatim,quote]
3687 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3689 @c Cannot document as they do not seem to operate consistently on all objects -td
3690 @c TODO investigate further
3694 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3696 @node Using the break-alignable-interface
3697 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3699 @cindex align to objects
3700 @cindex break-align-symbols
3702 Rehearsal marks and bar numbers may be aligned with notation
3703 objects other than bar lines. These objects include @code{ambitus},
3704 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3705 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3706 @code{time-signature}.
3708 By default, rehearsal marks and bar numbers will be horizontally
3709 centered above the object:
3711 @lilypond[verbatim,quote,relative=1]
3712 % The rehearsal mark will be centered above the Clef
3713 \override Score.RehearsalMark #'break-align-symbols = #'(clef)
3718 % The rehearsal mark will be centered above the Time Signature
3719 \override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
3725 % The rehearsal mark will be centered above the Breath Mark
3726 \override Score.RehearsalMark #'break-align-symbols = #'(breathing-sign)
3735 A list of possible target alignment objects may be specified. If
3736 some of the objects are invisible at that point due to the setting
3737 of @code{break-visibility} or the explicit visibility settings for
3738 keys and clefs, the rehearsal mark or bar number is aligned to the
3739 first object in the list which is visible. If no objects in the
3740 list are visible the object is aligned to the bar line. If the bar
3741 line is invisible the object is aligned to the place where the bar
3744 @lilypond[verbatim,quote,relative=1]
3745 % The rehearsal mark will be centered above the Key Signature
3746 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3751 % The rehearsal mark will be centered above the Clef
3752 \set Staff.explicitKeySignatureVisibility = #all-invisible
3753 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3758 % The rehearsal mark will be centered above the Bar Line
3759 \set Staff.explicitKeySignatureVisibility = #all-invisible
3760 \set Staff.explicitClefVisibility = #all-invisible
3761 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3768 The alignment of the rehearsal mark relative to the notation object
3769 can be changed, as shown in the following example. In a score with
3770 multiple staves, this setting should be done for all the staves.
3772 @lilypond[verbatim,quote,relative=1]
3773 % The RehearsalMark will be centered above the Key Signature
3774 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3780 % The RehearsalMark will be aligned with the left edge of the Key Signature
3781 \once \override Score.KeySignature #'break-align-anchor-alignment = #LEFT
3785 % The RehearsalMark will be aligned with the right edge of the Key Signature
3786 \once \override Score.KeySignature #'break-align-anchor-alignment = #RIGHT
3792 The rehearsal mark can also be offset to the right or left of the left
3793 edge by an arbitrary amount. The units are staff-spaces:
3795 @lilypond[verbatim,quote,relative=1]
3796 % The RehearsalMark will be aligned with the left edge of the Key Signature
3797 % and then shifted right by 3.5 staff-spaces
3798 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3799 \once \override Score.KeySignature #'break-align-anchor = #3.5
3803 % The RehearsalMark will be aligned with the left edge of the Key Signature
3804 % and then shifted left by 2 staff-spaces
3805 \once \override Score.KeySignature #'break-align-anchor = #-2
3812 @node Vertical grouping of grobs
3813 @subsection Vertical grouping of grobs
3815 @c TODO Expand this section
3817 The VerticalAlignment and VerticalAxisGroup grobs work together.
3818 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3819 etc. VerticalAlignment then vertically aligns the different grobs
3820 grouped together by VerticalAxisGroup. There is usually only one
3821 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3825 @node Modifying stencils
3826 @subsection Modifying stencils
3828 All layout objects have a @code{stencil} property which is part of
3829 the @code{grob-interface}. By default, this property is usually
3830 set to a function specific to the object that is tailor-made to
3831 render the symbol which represents it in the output. For example,
3832 the standard setting for the @code{stencil} property of the
3833 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3835 The standard symbol for any object can be replaced by modifying the
3836 @code{stencil} property to reference a different, specially-written,
3837 procedure. This requires a high level of knowledge of the internal
3838 workings of LilyPond, but there is an easier way which can often
3839 produce adequate results.
3841 This is to set the @code{stencil} property to the procedure which
3842 prints text -- @code{ly:text-interface::print} -- and to add a
3843 @code{text} property to the object which is set to contain the
3844 markup text which produces the required symbol. Due to the
3845 flexibility of markup, much can be achieved -- see in particular
3846 @ref{Graphic notation inside markup}.
3848 The following example demonstrates this by changing the note head
3849 symbol to a cross within a circle.
3851 @lilypond[verbatim,quote]
3853 \once \override NoteHead #'stencil = #ly:text-interface::print
3854 \once \override NoteHead #'text = \markup {
3856 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3857 \musicglyph #"noteheads.s2cross"
3865 Any of the glyphs in the feta Font can be supplied to the
3866 @code{\musicglyph} markup command -- see @ref{The Feta font}.
3868 @c TODO Add inserting eps files or ref to later
3870 @c TODO Add inserting Postscript or ref to later
3874 @ref{Graphic notation inside markup},
3875 @ref{Formatting text},
3876 @ref{Text markup commands},
3877 @ref{The Feta font}.
3880 @node Modifying shapes
3881 @subsection Modifying shapes
3884 * Modifying ties and slurs::
3887 @node Modifying ties and slurs
3888 @unnumberedsubsubsec Modifying ties and slurs
3890 @cindex slurs, modifying
3891 @cindex ties, modifying
3892 @cindex Bézier curves, control points
3893 @cindex control points, Bézier curves
3895 Ties, slurs and phrasing slurs are drawn as third-order Bézier
3896 curves. If the shape of the tie or slur which is calculated
3897 automatically is not optimum, the shape may be modified manually by
3898 explicitly specifying the four control points required to define
3899 a third-order Bézier curve.
3901 Third-order or cubic Bézier curves are defined by four control
3902 points. The first and fourth control points are precisely the
3903 starting and ending points of the curve. The intermediate two
3904 control points define the shape. Animations showing how the curve
3905 is drawn can be found on the web, but the following description
3906 may be helpful. The curve starts from the first control point
3907 heading directly towards the second, gradually bending over to
3908 head towards the third and continuing to bend over to head towards
3909 the fourth, arriving there travelling directly from the third
3910 control point. The curve is entirely contained in the
3911 quadrilateral defined by the four control points.
3913 Here is an example of a case where the tie is not optimum, and
3914 where @code{\tieDown} would not help.
3916 @lilypond[verbatim,quote,relative=1]
3920 { r4 <g c,> <g c,> <g c,> }
3924 One way of improving this tie is to manually modify its control
3927 The coordinates of the Bézier control points are specified in units
3928 of staff-spaces. The X@tie{}coordinate is relative to the reference
3929 point of the note to which the tie or slur is attached, and the
3930 Y@tie{}coordinate is relative to the staff center line. The
3931 coordinates are entered as a list of four pairs of decimal numbers
3932 (reals). One approach is to estimate the coordinates of the two
3933 end points, and then guess the two intermediate points. The optimum
3934 values are then found by trial and error.
3936 It is useful to remember that a symmetric curve requires symmetric
3937 control points, and that Bézier curves have the useful property that
3938 transformations of the curve such as translation, rotation and
3939 scaling can be achieved by applying the same transformation to the
3940 curve's control points.
3942 For the example above the following override gives a satisfactory
3943 tie. Note the placement -- it has to be immediately before the note
3944 to which the start of the tie (or slur) is attached.
3946 @lilypond[verbatim,quote,relative=1]
3950 #'control-points = #'((1 . -1) (3 . 0.6) (12.5 . 0.6) (14.5 . -1))
3954 { r4 <g c,> <g c,> <g c,> }
3959 It is not possible to modify shapes of ties or slurs by changing
3960 the @code{control-points} property if there are multiple ties or slurs
3961 at the same musical moment -- the @code{\tweak} command will also not
3962 work in this case. However, the @code{tie-configuration} property of
3963 @code{TieColumn} can be overridden to set start line and direction as
3967 Internals Reference:
3968 @rinternals{TieColumn}.
3970 @cindex Scheme, pure containers
3971 @cindex Scheme, unpure containers
3972 @cindex pure containers, Scheme
3973 @cindex unpure containers, Scheme
3974 @cindex horizontal spacing, overriding
3977 @node Unpure-pure containers
3978 @subsection Unpure-pure containers
3980 Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
3981 calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
3982 Scheme function instead of a literal (i.e. a number or pair).
3984 For certain grobs, the @code{Y-extent} is based on the @code{stencil}
3985 property, overriding the stencil property of one of these will
3986 require an additional @code{Y-extent} override with an unpure-pure
3987 container. When a function overrides a @code{Y-offset} and/or
3988 @code{Y-extent} it is assumed that this will trigger line breaking
3989 calculations too early during compilation. So the function is not
3990 evaluated at all (usually returning a value of @samp{0} or
3991 @samp{'(0 . 0)}) which can result in collisions. A @q{pure} function
3992 will not affect properties, objects or grob suicides and therefore will
3993 always have its Y-axis-related evaluated correctly.
3995 Currently, there are about thirty functions that are already considered
3996 @q{pure} and Unpure-pure containers are a way to set functions not on
3997 this list as @q{pure}. The @q{pure} function is evaluated @emph{before}
3998 any line-breaking and so the horizontal spacing can be adjusted
3999 @q{in time}. The @q{unpure} function is then evaluated @emph{after}
4002 @warning{As it is difficult to always know which functions are on this
4003 list we recommend that any @q{pure} functions you create do not use
4004 @code{Beam} or @code{VerticalAlignment} grobs.}
4006 An unpure-pure container is constructed as follows;
4008 @code{(ly:make-unpure-pure-container f0 f1)}
4010 where @code{f0} is a function taking @var{n} arguments (@var{n >= 1})
4011 and the first argument must always be the grob. This is the function
4012 that gives the actual result. @var{f1} is the function being labeled
4013 as @q{pure} that takes @var{n + 2} arguments. Again, the first argument
4014 must always still be the grob but the second and third are @q{start}
4015 and @q{end} arguments.
4017 @var{start} and @var{end} are, for all intents and purposes, dummy
4018 values that only matter for @code{Spanners} (i.e @code{Hairpin} or
4019 @code{Beam}), that can return different height estimations based on a
4020 starting and ending column.
4022 The rest are the other arguments to the first function (which
4023 may be none if @var{n = 1}).
4025 The results of the second function are used as an approximation of the
4026 value needed which is then used by the first function to get the real
4027 value which is then used for fine-tuning much later during the spacing
4030 @lilypond[verbatim,quote,ragged-right]
4031 #(define (square-line-circle-space grob)
4032 (let* ((pitch (ly:event-property (ly:grob-property grob 'cause) 'pitch))
4033 (notename (ly:pitch-notename pitch)))
4034 (if (= 0 (modulo notename 2))
4035 (make-circle-stencil 0.5 0.0 #t)
4036 (make-filled-box-stencil '(0 . 1.0)
4039 squareLineCircleSpace = {
4040 \override NoteHead #'stencil = #square-line-circle-space
4043 smartSquareLineCircleSpace = {
4044 \squareLineCircleSpace
4045 \override NoteHead #'Y-extent =
4046 #(ly:make-unpure-pure-container
4047 ly:grob::stencil-height
4048 (lambda (grob start end) (ly:grob::stencil-height grob)))
4051 \new Voice \with { \remove "Stem_engraver" }
4053 \squareLineCircleSpace
4055 \smartSquareLineCircleSpace
4060 In the first measure, without the unpure-pure container, the spacing
4061 engine does not know the width of the note head and lets it collide with
4062 the accidentals. In the second measure, with unpure-pure containers,
4063 the spacing engine knows the width of the note heads and avoids the
4064 collision by lengthening the line accordingly.
4066 Usually for simple calculations nearly-identical functions for both the
4067 @q{unpure} and @q{pure} parts can be used, by only changing the number
4068 of arguments passed to, and the scope of, the function.
4070 @warning{If a function is labeled as @q{pure} and it turns out not to
4071 be, the results can be unexpected.}
4074 @node Using music functions
4075 @section Using music functions
4077 @c TODO -- add @seealso, etc. to these subsections
4079 Where tweaks need to be reused with different music expressions,
4080 it is often convenient to make the tweak part of a @emph{music
4081 function}. In this section, we discuss only @emph{substitution}
4082 functions, where the object is to substitute a variable into a
4083 piece of LilyPond input code. Other more complex functions are
4084 described in @rextend{Music functions}.
4087 * Substitution function syntax::
4088 * Substitution function examples::
4091 @node Substitution function syntax
4092 @subsection Substitution function syntax
4094 Making a function that substitutes a variable into LilyPond
4095 code is easy. The general form of these functions is
4099 #(define-music-function
4100 (parser location @var{arg1} @var{arg2} @dots{})
4101 (@var{type1?} @var{type2?} @dots{})
4103 @var{@dots{}music@dots{}}
4110 @multitable @columnfractions .33 .66
4111 @item @code{@var{argN}}
4112 @tab @var{n}th argument
4114 @item @code{@var{typeN?}}
4115 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
4116 must return @code{#t}.
4118 @item @code{@var{@dots{}music@dots{}}}
4119 @tab normal LilyPond input, using @code{$} (in places where only
4120 Lilypond constructs are allowed) or @code{#} (to use it as a Scheme
4121 value or music function argument or music inside of music lists) to
4126 The @code{parser} and @code{location} arguments are mandatory, and
4127 are used in some advanced situations as described in the
4128 @q{Extending} manual (see @rextend{Music functions}). For
4129 substitution functions, just be sure to include them.
4131 The list of type predicates is also required. Some of the most
4132 common type predicates used in music functions are:
4136 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
4148 For a list of available type predicates, see
4149 @ref{Predefined type predicates}. User-defined type predicates
4154 @ref{Predefined type predicates}.
4157 @rextend{Music functions}.
4160 @file{lily/music-scheme.cc},
4162 @file{scm/lily.scm}.
4165 @node Substitution function examples
4166 @subsection Substitution function examples
4168 This section introduces some substitution function examples.
4169 These are not intended to be exhaustive, but rather to demonstrate
4170 some of the possibilities of simple substitution functions.
4172 In the first example, a function is defined that simplifies
4173 setting the padding of a TextScript:
4175 @lilypond[quote,verbatim,ragged-right]
4177 #(define-music-function
4178 (parser location padding)
4181 \once \override TextScript #'padding = #padding
4185 c4^"piu mosso" b a b
4187 c4^"piu mosso" d e f
4189 c4^"piu mosso" fis a g
4193 In addition to numbers, we can use music expressions such
4194 as notes for arguments to music functions:
4196 @lilypond[quote,verbatim,ragged-right]
4198 #(define-music-function
4199 (parser location note)
4202 \tweak NoteHead #'stencil #ly:text-interface::print
4203 \tweak NoteHead #'text
4204 \markup \musicglyph #"custodes.mensural.u0"
4205 \tweak Stem #'stencil ##f
4209 \relative c' { c4 d e f \custosNote g }
4212 Substitution functions with multiple arguments can be defined:
4214 @lilypond[quote,verbatim,ragged-right]
4216 #(define-music-function
4217 (parser location padding tempotext)
4220 \once \override Score.MetronomeMark #'padding = #padding
4221 \tempo \markup { \bold #tempotext }
4225 \tempo \markup { "Low tempo" }
4227 \tempoPadded #4.0 "High tempo"
4232 @c TODO: add appropriate @@ref's here.