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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 Usually the order in which the engravers are specified
676 does not matter, but in a few special cases the order
677 is important, for example where one engraver writes
678 a property and another reads it, or where one engraver
679 creates a grob and another must process it. The order in
680 which the engravers are specified is the order in which
681 they are called to carry out their processing.
683 The following orderings are important: the
684 @code{Bar_engraver} must normally be first, and
685 the @code{New_fingering_engraver} must come before
686 the @code{Script_column_engraver}. There may be others
687 with ordering dependencies.
689 @node Changing context default settings
690 @subsection Changing context default settings
692 @cindex default context properties, changing
693 @cindex context properties, changing defaults
695 Context and grob properties can be changed with @code{\set}
696 and @code{\override} commands, as described in
697 @ref{Modifying properties}. These commands create music events,
698 making the changes take effect at the point in time the music
701 In contrast, this section explains how to change the @emph{default}
702 values of context and grob properties at the time the context is
703 created. There are two ways of doing this. One modifies the default
704 values in all contexts of a particular type, the other modifies the
705 default values in just one particular instance of a context.
708 * Changing all contexts of the same type::
709 * Changing just one specific context::
710 * Order of precedence::
713 @node Changing all contexts of the same type
714 @unnumberedsubsubsec Changing all contexts of the same type
716 @cindex \context in \layout block
720 The context settings which are to be used by default in
721 @code{Score}, @code{Staff}, @code{Voice} and other contexts may be
722 specified in a @code{\context} block within any @code{\layout} block.
723 The @code{\layout} block should be placed within the @code{\score}
724 block to which it is to apply, after the music.
730 [context settings for all Voice contexts]
734 [context settings for all Staff contexts]
739 The following types of settings may be specified:
743 An @code{\override} command, but with the context name omitted
745 @lilypond[quote,verbatim]
748 a4^"Thicker stems" a a a
754 \override Stem #'thickness = #4.0
761 Directly setting a context property
763 @lilypond[quote,verbatim]
766 a4^"Smaller font" a a a
779 A predefined command such as @code{\dynamicUp} or a music
780 expression like @code{\accidentalStyle "dodecaphonic"}
782 @lilypond[quote,verbatim]
785 a4^"Dynamics above" a a a
795 \accidentalStyle "dodecaphonic"
802 A user-defined variable containing a @code{\with} block; for details
803 of the @code{\with} block see
804 @ref{Changing just one specific context}.
806 @lilypond[quote,verbatim]
807 StaffDefaults = \with {
814 a4^"Smaller font" a a a
829 Property-setting commands can be placed in a @code{\layout} block
830 without being enclosed in a @code{\context} block. Such settings
831 are equivalent to including the same property-setting commands at
832 the start of every context of the type specified. If no context
833 is specified @emph{every} bottom-level context is affected, see
834 @ref{Bottom-level contexts - voices}. The syntax of a
835 property-setting command in a @code{\layout} block is the same as
836 the same command written in the music stream.
838 @lilypond[quote,verbatim]
842 a4^"Smaller font" a a a
847 \accidentalStyle "dodecaphonic"
849 \override Voice.Stem #'thickness = #4.0
855 @node Changing just one specific context
856 @unnumberedsubsubsec Changing just one specific context
861 The context properties of just one specific context instance can be
862 changed in a @code{\with} block. All other context instances of the
863 same type retain the default settings built into LilyPond and modified
864 by any @code{\layout} block within scope. The @code{\with} block
865 must be placed immediately after the @code{\new} @var{context-type}
871 [context settings for this context instance only]
877 The following types of settings may be specified:
881 An @code{\override} command, but with the context name omitted
883 @lilypond[quote,verbatim]
888 \override Stem #'thickness = #4.0
892 a4^"Thick stems" a a a
901 Directly setting a context property
903 @lilypond[quote,verbatim]
908 a4^"Default font" a a a
917 a4^"Smaller font" a a a
926 A predefined command such as @code{\dynamicUp}
928 @lilypond[quote,verbatim]
934 a4^"Dynamics below" a a a
940 \with { \accidentalStyle "dodecaphonic" }
946 a4^"Dynamics above" a a a
957 @node Order of precedence
958 @unnumberedsubsubsec Order of precedence
960 The value of a property which applies at a particular time is
961 determined as follows:
965 if an @code{\override} or @code{\set} command in the input stream is
966 in effect that value is used,
969 otherwise the default value taken from a @code{\with} statement
970 on the context initiation statement is used,
973 otherwise the default value taken from the most recent appropriate
974 @code{\context} block in the @code{\layout} blocks is used,
977 otherwise the LilyPond built-in default is used.
982 @rlearning{Modifying context properties}.
985 @ref{Contexts explained},
986 @ref{Bottom-level contexts - voices},
987 @ref{The set command},
988 @ref{The override command},
989 @ref{The \layout block}.
992 @node Defining new contexts
993 @subsection Defining new contexts
995 @cindex contexts, defining new
996 @cindex engravers, including in contexts
1011 Specific contexts, like @code{Staff} and @code{Voice}, are made of
1012 simple building blocks. It is possible to create new types of
1013 contexts with different combinations of engraver plug-ins.
1015 The next example shows how to build a different type of
1016 @code{Voice} context from scratch. It will be similar to
1017 @code{Voice}, but only prints centered slash note heads. It can be used
1018 to indicate improvisation in jazz pieces,
1020 @lilypond[quote,ragged-right]
1021 \layout { \context {
1023 \type "Engraver_group"
1024 \consists "Note_heads_engraver"
1025 \consists "Rhythmic_column_engraver"
1026 \consists "Text_engraver"
1027 \consists Pitch_squash_engraver
1028 squashedPosition = #0
1029 \override NoteHead #'style = #'slash
1030 \override Stem #'transparent = ##t
1031 \override Flag #'transparent = ##t
1035 \accepts "ImproVoice"
1039 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1040 c4 c^"undress" c_"while playing :)" c }
1046 These settings are defined within a @code{\context} block inside a
1047 @code{\layout} block,
1057 In the following discussion, the example input shown should go in place
1058 of the @dots{} in the previous fragment.
1060 First it is necessary to define a name for the new context:
1066 Since it is similar to the @code{Voice}, we want commands that work
1067 on (existing) @code{Voice}s to remain working. This is achieved by
1068 giving the new context an alias @code{Voice},
1074 The context will print notes and instructive texts, so we need to add
1075 the engravers which provide this functionality,
1078 \consists Note_heads_engraver
1079 \consists Text_engraver
1082 but we only need this on the center line,
1085 \consists Pitch_squash_engraver
1086 squashedPosition = #0
1089 The @rinternals{Pitch_squash_engraver} modifies note heads (created
1090 by @rinternals{Note_heads_engraver}) and sets their vertical
1091 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
1094 The notes look like a slash, and have no stem,
1097 \override NoteHead #'style = #'slash
1098 \override Stem #'transparent = ##t
1099 \override Flag #'transparent = ##t
1102 All these plug-ins have to cooperate, and this is achieved with a
1103 special plug-in, which must be marked with the keyword @code{\type}.
1104 This should always be @code{Engraver_group}.
1107 \type "Engraver_group"
1110 Put together, we get
1115 \type "Engraver_group"
1116 \consists "Note_heads_engraver"
1117 \consists "Text_engraver"
1118 \consists Pitch_squash_engraver
1119 squashedPosition = #0
1120 \override NoteHead #'style = #'slash
1121 \override Stem #'transparent = ##t
1122 \override Flag #'transparent = ##t
1128 Contexts form hierarchies. We want to hang the @code{ImproVoice}
1129 under @code{Staff}, just like normal @code{Voice}s. Therefore, we
1130 modify the @code{Staff} definition with the @code{\accepts}
1141 The opposite of @code{\accepts} is @code{\denies},
1142 which is sometimes needed when reusing existing context definitions.
1144 Putting both into a @code{\layout} block, like
1154 \accepts "ImproVoice"
1159 Then the output at the start of this subsection can be entered as
1167 c c_"while playing :)"
1174 @node Context layout order
1175 @subsection Context layout order
1177 @cindex contexts, layout order
1181 Contexts are normally positioned in a system from top to bottom
1182 in the order in which they are encountered in the input file. When
1183 contexts are nested, the outer context will include inner nested
1184 contexts as specified in the input file, provided the inner contexts
1185 are included in the outer context's @qq{accepts} list. Nested
1186 contexts which are not included in the outer context's @qq{accepts}
1187 list will be repositioned below the outer context rather than nested
1190 The @qq{accepts} list of a context can be changed with the
1191 @code{\accepts} and @code{\denies} commands. @code{\accepts} adds a
1192 context to the @qq{accepts} list and @code{\denies} removes a context
1193 from the list. For example, it would not normally be desirable for
1194 chord names to be nested within a @code{Staff} context, so the
1195 @code{ChordNames} context is not included by default in the @qq{accepts}
1196 list of the @code{Staff} context, but if this were to be required it can
1199 @lilypond[verbatim,quote]
1203 \chords { d1:m7 b1:min7.5- }
1208 @lilypond[verbatim,quote]
1212 \chords { d1:m7 b1:min7.5- }
1217 \accepts "ChordNames"
1223 @code{\denies} is mainly used when a new context is being based on
1224 another, but the required nesting differs. For example, the
1225 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1226 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1227 context in the @qq{accepts} list.
1229 Note that a context will be silently created implicitly if a command
1230 is encountered when there is no suitable context available to
1231 contain it. This can give rise to unexpected new staves or scores.
1233 @cindex alignAboveContext
1234 @cindex alignBelowContext
1235 @funindex alignAboveContext
1236 @funindex alignBelowContext
1238 Sometimes a context is required to exist for just a brief period, a
1239 good example being the staff context for an ossia. This is usually
1240 achieved by introducing the context definition at the appropriate
1241 place in parallel with corresponding section of the main music.
1242 By default, the temporary context will be placed below all the
1243 existing contexts. To reposition it above the context called
1244 @qq{main}, it should be defined like this:
1247 @code{\new Staff \with @{ alignAboveContext = #"main" @} }
1250 A similar situation arises when positioning a temporary lyrics
1251 context within a multi-staved layout such as a @code{ChoirStaff},
1252 for example, when adding a second verse to a repeated section.
1253 By default the temporary lyrics context will be placed beneath the
1254 lower staves. By defining the temporary lyrics context with
1255 @code{alignBelowContext} it can be positioned correctly beneath
1256 the (named) lyrics context containing the first verse.
1258 Examples showing this repositioning of temporary contexts can be
1259 found elsewhere --- see @rlearning{Nesting music expressions},
1260 @ref{Modifying single staves} and @ref{Techniques specific to lyrics}.
1264 @rlearning{Nesting music expressions}.
1267 @ref{Modifying single staves},
1268 @ref{Techniques specific to lyrics}.
1271 @rprogram{An extra staff appears}.
1274 @file{ly/engraver-init.ly}.
1277 @node Explaining the Internals Reference
1278 @section Explaining the Internals Reference
1281 * Navigating the program reference::
1282 * Layout interfaces::
1283 * Determining the grob property::
1284 * Naming conventions::
1287 @node Navigating the program reference
1288 @subsection Navigating the program reference
1290 @c TODO remove this (it's in the LM)
1291 @c Replace with more factual directions
1293 Suppose we want to move the fingering indication in the fragment
1296 @lilypond[quote,relative=2,verbatim]
1302 If you visit the documentation on fingering instructions (in
1303 @ref{Fingering instructions}), you will notice:
1308 Internals Reference: @rinternals{Fingering}.
1313 @c outdated info; probably will delete.
1315 This fragment points to two parts of the program reference: a page
1316 on @code{FingeringEvent} and one on @code{Fingering}.
1318 The page on @code{FingeringEvent} describes the properties of the music
1319 expression for the input @w{@code{-2}}. The page contains many links
1320 forward. For example, it says
1323 Accepted by: @rinternals{Fingering_engraver},
1327 That link brings us to the documentation for the Engraver, the
1331 This engraver creates the following layout objects: @rinternals{Fingering}.
1334 In other words, once the @code{FingeringEvent}s are interpreted, the
1335 @code{Fingering_engraver} plug-in will process them.
1339 @c I can't figure out what this is supposed to mean. -gp
1341 The @code{Fingering_engraver} is also listed to create
1342 @rinternals{Fingering} objects,
1344 @c old info? it doesn't make any sense to me with our current docs.
1346 second bit of information listed under @b{See also} in the Notation
1351 The programmer's reference is available as an HTML document. It is
1352 highly recommended that you read it in HTML form, either online or
1353 by downloading the HTML documentation. This section will be much more
1354 difficult to understand if you are using the
1358 Follow the link to @rinternals{Fingering}. At the top of the
1362 Fingering objects are created by: @rinternals{Fingering_engraver} and
1363 @rinternals{New_fingering_engraver}.
1366 By following related links inside the program reference, we can follow the
1367 flow of information within the program:
1371 @item @rinternals{Fingering}:
1372 @rinternals{Fingering} objects are created by:
1373 @rinternals{Fingering_engraver}
1375 @item @rinternals{Fingering_engraver}:
1376 Music types accepted: @rinternals{fingering-event}
1378 @item @rinternals{fingering-event}:
1379 Music event type @code{fingering-event} is in Music expressions named
1380 @rinternals{FingeringEvent}
1383 This path goes against the flow of information in the program: it
1384 starts from the output, and ends at the input event. You could
1385 also start at an input event, and read with the flow of
1386 information, eventually ending up at the output object(s).
1388 The program reference can also be browsed like a normal document. It
1389 contains chapters on
1391 @rinternals{Music definitions},
1394 @code{Music definitions}
1396 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1397 chapter lists all the definitions used and all properties that may be
1401 @node Layout interfaces
1402 @subsection Layout interfaces
1404 @cindex interface, layout
1405 @cindex layout interface
1408 The HTML page that we found in the previous section describes the
1409 layout object called @rinternals{Fingering}. Such an object is a
1410 symbol within the score. It has properties that store numbers (like
1411 thicknesses and directions), but also pointers to related objects. A
1412 layout object is also called a @emph{Grob}, which is short for Graphical
1413 Object. For more details about Grobs, see @rinternals{grob-interface}.
1415 The page for @code{Fingering} lists the definitions for the
1416 @code{Fingering} object. For example, the page says
1419 @code{padding} (dimension, in staff space):
1425 which means that the number will be kept at a distance of at least 0.5
1429 Each layout object may have several functions as a notational or
1430 typographical element. For example, the Fingering object
1431 has the following aspects
1435 Its size is independent of the horizontal spacing, unlike slurs or beams.
1438 It is a piece of text. Granted, it is usually a very short text.
1441 That piece of text is typeset with a font, unlike slurs or beams.
1444 Horizontally, the center of the symbol should be aligned to the
1445 center of the note head.
1448 Vertically, the symbol is placed next to the note and the staff.
1451 The vertical position is also coordinated with other superscript
1452 and subscript symbols.
1455 Each of these aspects is captured in so-called @emph{interface}s,
1456 which are listed on the @rinternals{Fingering} page at the bottom
1459 This object supports the following interfaces:
1460 @rinternals{item-interface},
1461 @rinternals{self-alignment-interface},
1462 @rinternals{side-position-interface}, @rinternals{text-interface},
1463 @rinternals{text-script-interface}, @rinternals{font-interface},
1464 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1467 Clicking any of the links will take you to the page of the respective
1468 object interface. Each interface has a number of properties. Some of
1469 them are not user-serviceable (@q{Internal properties}), but others
1472 We have been talking of @emph{the} @code{Fingering} object, but actually it
1473 does not amount to much. The initialization file (see
1474 @rlearning{Other sources of information})
1475 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1480 (avoid-slur . around)
1481 (slur-padding . 0.2)
1482 (staff-padding . 0.5)
1483 (self-alignment-X . 0)
1484 (self-alignment-Y . 0)
1485 (script-priority . 100)
1486 (stencil . ,ly:text-interface::print)
1487 (direction . ,ly:script-interface::calc-direction)
1488 (font-encoding . fetaText)
1489 (font-size . -5) ; don't overlap when next to heads.
1490 (meta . ((class . Item)
1491 (interfaces . (finger-interface
1493 text-script-interface
1495 side-position-interface
1496 self-alignment-interface
1497 item-interface))))))
1501 As you can see, the @code{Fingering} object is nothing more than a
1502 bunch of variable settings, and the webpage in the Internals Reference
1503 is directly generated from this definition.
1506 @node Determining the grob property
1507 @subsection Determining the grob property
1509 @c TODO remove this (it's in the LM)
1510 @c Replace with more factual directions
1512 Recall that we wanted to change the position of the @b{2} in
1514 @lilypond[quote,relative=2,verbatim]
1520 Since the @b{2} is vertically positioned next to its note, we have to
1521 meddle with the interface associated with this positioning. This is
1522 done using @code{side-position-interface}. The page for this interface
1526 @code{side-position-interface}
1528 Position a victim object (this one) next to other objects (the
1529 support). The property @code{direction} signifies where to put the
1530 victim object relative to the support (left or right, up or down?)
1535 Below this description, the variable @code{padding} is described as
1540 (dimension, in staff space)
1542 Add this much extra space between objects that are next to each other.
1546 By increasing the value of @code{padding}, we can move the
1547 fingering away from the note head. The following command inserts
1548 3 staff spaces of white
1549 between the note and the fingering:
1551 \once \override Voice.Fingering #'padding = #3
1554 Inserting this command before the Fingering object is created,
1555 i.e., before @code{c2}, yields the following result:
1557 @lilypond[quote,relative=2,verbatim]
1558 \once \override Voice.Fingering #'padding = #3
1565 In this case, the context for this tweak is @code{Voice}. This
1566 fact can also be deduced from the program reference, for the page for
1567 the @rinternals{Fingering_engraver} plug-in says
1570 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1574 @node Naming conventions
1575 @subsection Naming conventions
1577 Another thing that is needed, is an overview of the various naming
1581 @item scheme functions: lowercase-with-hyphens (incl. one-word
1583 @item scheme functions: ly:plus-scheme-style
1584 @item music events, music classes and music properties:
1586 @item Grob interfaces: scheme-style
1587 @item backend properties: scheme-style (but X and Y!)
1588 @item contexts (and MusicExpressions and grobs): Capitalized or
1590 @item context properties: lowercaseFollowedByCamelCase
1592 Capitalized_followed_by_lowercase_and_with_underscores
1595 Questions to be answered:
1597 @item Which of these are conventions and which are rules?
1598 @item Which are rules of the underlying language, and which are
1602 @node Modifying properties
1603 @section Modifying properties
1605 @c TODO change the menu and subsection node names to use
1606 @c backslash once the new macro to handle the refs
1607 @c is available. Need to find and change all refs at
1608 @c the same time. -td
1611 * Overview of modifying properties::
1613 * The override command::
1614 * The tweak command::
1615 * set versus override::
1616 * Modifying alists::
1620 @node Overview of modifying properties
1621 @subsection Overview of modifying properties
1623 Each context is responsible for creating certain types of graphical
1624 objects. The settings used for printing these objects are also stored by
1625 context. By changing these settings, the appearance of objects can be
1628 There are two different kinds of properties stored in contexts:
1629 context properties and grob properties. Context properties are
1630 properties that apply to the context as a whole and control
1631 how the context itself is displayed. In contrast, grob properties
1632 apply to specific grob types that will be displayed in the context.
1634 The @code{\set} and @code{\unset} commands are used to change values
1635 for context properties. The @code{\override} and @code{\revert}
1636 commands are used to change values for grob properties.
1639 The syntax for this is
1642 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1645 Here @var{name} is the name of a graphical object, like
1646 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1647 variable of the formatting system (@q{grob property} or @q{layout
1648 property}). The latter is a symbol, so it must be quoted. The
1649 subsection @ref{Modifying properties}, explains what to fill in
1650 for @var{name}, @var{property}, and @var{value}. Here we only
1651 discuss the functionality of this command.
1656 \override Staff.Stem #'thickness = #4.0
1660 makes stems thicker (the default is 1.3, with staff line thickness as a
1661 unit). Since the command specifies @code{Staff} as context, it only
1662 applies to the current staff. Other staves will keep their normal
1663 appearance. Here we see the command in action:
1665 @lilypond[quote,verbatim,relative=2]
1667 \override Staff.Stem #'thickness = #4.0
1673 The @code{\override} command changes the definition of the @code{Stem}
1674 within the current @code{Staff}. After the command is interpreted
1675 all stems are thickened.
1677 Analogous to @code{\set}, the @var{context} argument may be left out,
1678 causing the default context @code{Voice} to be used. Adding
1679 @code{\once} applies the change during one timestep only.
1681 @lilypond[quote,verbatim,relative=2]
1683 \once \override Stem #'thickness = #4.0
1688 The @code{\override} must be done before the object is
1689 started. Therefore, when altering @emph{Spanner} objects such as slurs
1690 or beams, the @code{\override} command must be executed at the moment
1691 when the object is created. In this example,
1693 @lilypond[quote,verbatim,relative=2]
1694 \override Slur #'thickness = #3.0
1696 \override Beam #'beam-thickness = #0.6
1701 the slur is fatter but the beam is not. This is because the command for
1702 @code{Beam} comes after the Beam is started, so it has no effect.
1704 Analogous to @code{\unset}, the @code{\revert} command for a context
1705 undoes an @code{\override} command; like with @code{\unset}, it only
1706 affects settings that were made in the same context. In other words, the
1707 @code{\revert} in the next example does not do anything.
1710 \override Voice.Stem #'thickness = #4.0
1711 \revert Staff.Stem #'thickness
1714 Some tweakable options are called @q{subproperties} and reside inside
1715 properties. To tweak those, use commands of the form
1717 @c leave this as a long long
1719 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1726 \override Stem #'(details beamed-lengths) = #'(4 4 3)
1732 Internals Reference:
1733 @rinternals{Backend},
1734 @rinternals{All layout objects},
1735 @rinternals{OverrideProperty},
1736 @rinternals{RevertProperty},
1737 @rinternals{PropertySet}.
1740 The back-end is not very strict in type-checking object properties.
1741 Cyclic references in Scheme values for properties can cause hangs
1742 or crashes, or both.
1745 @node The set command
1746 @subsection The @code{@bs{}set} command
1750 @cindex changing properties
1752 Each context has a set of @emph{properties}, variables contained
1753 in that context. Context properties are changed with the @code{\set}
1754 command, which has the following syntax:
1757 \set @var{context}.@var{property} = #@var{value}
1760 @var{value} is a Scheme object, which is why it must be preceded by
1761 the @code{#}@tie{}character.
1763 Contexts properties are usually named in
1764 @code{studlyCaps}. They mostly control the translation from
1765 music to notation, e.g. @code{localKeySignature} (for determining
1766 whether to print accidentals), or @code{measurePosition} (for
1767 determining when to print a bar line). Context properties can
1768 change value over time while interpreting a piece of music;
1769 @code{measurePosition} is an obvious example of
1770 this. Context properties are modified with @code{\set}.
1772 For example, multimeasure rests will be combined into a single bar
1773 if the context property @code{skipBars} is set to @code{#t}:
1775 @lilypond[quote,verbatim,relative=2]
1777 \set Score.skipBars = ##t
1781 If the @var{context} argument is left out, then the property will be
1782 set in the current bottom context (typically @code{ChordNames},
1783 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1785 @lilypond[quote,verbatim,relative=2]
1786 \set Score.autoBeaming = ##f
1790 \set autoBeaming = ##t
1798 The change is applied @q{on-the-fly}, during the music, so that the
1799 setting only affects the second group of eighth notes.
1801 Note that the bottom-most context does not always contain the property
1802 that you wish to change -- for example, attempting to set the
1803 @code{skipBars} property of the default bottom context, in this case
1804 @code{Voice}, will have no effect, because skipBars is a property of
1805 the @code{Score} context.
1807 @lilypond[quote,verbatim,relative=2]
1813 Contexts are hierarchical, so if an enclosing context was specified, for
1814 example @code{Staff}, then the change would also apply to all
1815 @code{Voice}s in the current staff.
1819 The @code{\unset} command:
1822 \unset @var{context}.@var{property}
1826 is used to remove the definition of @var{property} from
1827 @var{context}. This command removes
1828 the definition only if it is set in @var{context}.
1829 Properties that have been set in enclosing contexts will
1830 not be altered by an unset in an enclosed context:
1832 @lilypond[quote,verbatim,relative=2]
1833 \set Score.autoBeaming = ##t
1838 \unset Score.autoBeaming
1846 Like @code{\set}, the @var{context} argument does not have to be
1847 specified for a bottom context, so the two statements
1850 \set Voice.autoBeaming = ##t
1851 \set autoBeaming = ##t
1855 are equivalent if the current bottom context is @code{Voice}.
1859 Preceding a @code{\set} command by @code{\once} makes the
1860 setting apply to only a single time-step:
1862 @lilypond[quote,verbatim,relative=2]
1864 \once \set fontSize = #4.7
1869 A full description of all available context properties is in the
1870 internals reference, see
1872 @rinternals{Tunable context properties}.
1875 Translation @expansion{} Tunable context properties.
1879 Internals Reference:
1880 @rinternals{Tunable context properties}.
1882 @cindex grob properties
1883 @cindex properties, grob
1887 @node The override command
1888 @subsection The @code{\override} command
1890 There is a special type of context property: the grob
1891 description. Grob descriptions are named in @code{StudlyCaps}
1892 (starting with capital letters). They contain the
1893 @q{default settings} for a particular kind of grob as an
1894 association list. See @file{scm/define-grobs.scm}
1895 to see the settings for each grob description. Grob descriptions
1896 are modified with @code{\override}.
1898 @code{\override} is actually a shorthand;
1901 \override @var{context}.@var{GrobName} #'@var{property} = #@var{value}
1905 is more or less equivalent to
1907 @c leave this long line -gp
1909 \set @var{context}.@var{GrobName} =
1910 #(cons (cons '@var{property} @var{value})
1911 <previous value of @var{context}.@var{GrobName}>)
1914 The value of @code{context}.@code{GrobName} (the alist) is used to initialize
1915 the properties of individual grobs. Grobs have
1916 properties, named in Scheme style, with
1917 @code{dashed-words}. The values of grob properties change
1918 during the formatting process: formatting basically amounts
1919 to computing properties using callback functions.
1921 For example, we can increase the thickness of a note stem by
1922 overriding the @code{thickness} property of the @code{Stem}
1925 @lilypond[quote,verbatim,relative=2]
1927 \override Voice.Stem #'thickness = #3.0
1931 If no context is specified in an @code{\override}, the bottom
1934 @lilypond[quote,verbatim,relative=2]
1935 { \override Staff.Stem #'thickness = #3.0
1939 \override Stem #'thickness = #0.5
1949 @cindex reverting overrides
1950 @cindex overrides, reverting
1952 The effects of @code{\override} can be undone by @code{\revert}:
1954 @lilypond[quote,verbatim,relative=2]
1956 \override Voice.Stem #'thickness = #3.0
1958 \revert Voice.Stem #'thickness
1962 The effects of @code{\override} and @code{\revert} apply to all
1963 grobs in the affected context from the current time forward:
1965 @lilypond[quote,verbatim,relative=2]
1970 \override Staff.Stem #'thickness = #3.0
1974 \revert Staff.Stem #'thickness
1982 @cindex overriding for only one moment
1984 @code{\once} can be used with @code{\override}
1985 to affect only the current time step:
1987 @lilypond[quote,verbatim,relative=2]
1991 \override Stem #'thickness = #3.0
1995 \once \override Stem #'thickness = #3.0
2004 Commands which change output generally look like
2007 \override Voice.Stem #'thickness = #3.0
2011 To construct this tweak we must determine these bits of information:
2014 @item the context: here @code{Voice}.
2015 @item the layout object: here @code{Stem}.
2016 @item the layout property: here @code{thickness}.
2017 @item a sensible value: here @code{3.0}.
2020 Some tweakable options are called @q{subproperties} and reside inside
2021 properties. To tweak those, use commands in the form
2024 \override Stem #'(details beamed-lengths) = #'(4 4 3)
2027 @cindex internal documentation
2028 @cindex finding graphical objects
2029 @cindex graphical object descriptions
2032 @cindex internal documentation
2034 For many properties, regardless of the data type of the property, setting the
2035 property to false (@code{#f}) will result in turning it off, causing
2036 LilyPond to ignore that property entirely. This is particularly useful for
2037 turning off grob properties which may otherwise be causing problems.
2039 We demonstrate how to glean this information from the notation manual
2040 and the program reference.
2044 Internals Reference:
2045 @rinternals{Backend}
2048 @node The tweak command
2049 @subsection The @code{\tweak} command
2054 Changing grob properties
2055 with @code{\override} causes the changes to apply to all of the
2056 given grobs in the context at the moment the change applies.
2057 Sometimes, however, it is desirable to have changes apply to just
2058 one grob, rather than to all grobs in the affected context. This is
2059 accomplished with the @code{\tweak} command, which has the following
2063 \tweak @var{layout-object} #'@var{grob-property} @var{value}
2066 Specifying @var{layout-object} is optional.
2067 The @code{\tweak} command applies to the music object that immediately
2068 follows @var{value} in the music stream.
2071 In some cases, it is possible to take a short-cut for tuning
2072 graphical objects. For objects that are created directly from
2073 an item in the input file, you can use the @code{\tweak} command.
2076 @lilypond[relative=2,verbatim,quote]
2081 \tweak #'duration-log #1
2084 -\tweak #'padding #8
2090 But the main use of the @code{\tweak} command is to modify just
2091 one of a number of notation elements which start at the same musical
2092 moment, like the notes of a chord, or tuplet brackets which start
2095 The @code{\tweak} command sets a property in the following object
2096 directly, without requiring the grob name or context to be
2097 specified. For this to work, it is necessary for the @code{\tweak}
2098 command to remain immediately adjacent to the object to which it is
2099 to apply after the input file has been converted to a music stream.
2100 This is often not the case, as many additional elements are inserted
2101 into the music stream implicitly. For example, when a note which is
2102 not part of a chord is processed, LilyPond implicitly inserts a
2103 @code{ChordEvent} event before the note, so separating the tweak
2104 from the note. However, if chord symbols are placed round the
2105 tweak and the note, the @code{\tweak} command comes after the
2106 @code{ChordEvent} in the music stream, so remaining adjacent to the
2107 note, and able to modify it.
2111 @lilypond[relative=2,verbatim,quote]
2112 <\tweak #'color #red c>4
2118 @lilypond[relative=2,verbatim,quote]
2119 \tweak #'color #red c4
2124 For an introduction to the syntax and uses of the tweak command
2125 see @rlearning{Tweaking methods}.
2127 When several similar items are placed at the same musical moment,
2128 the @code{\override} command cannot be used to modify just one of
2129 them -- this is where the @code{\tweak} command must be used.
2130 Items which may appear more than once at the same musical moment
2131 include the following:
2133 @c TODO expand to include any further uses of \tweak
2135 @item note heads of notes inside a chord
2136 @item articulation signs on a single note
2137 @item ties between notes in a chord
2138 @item tuplet brackets starting at the same time
2141 @c TODO add examples of these
2143 @cindex chord, modifying one note in
2145 In this example, the color of one note head and the type of another
2146 note head are modified within a single chord:
2148 @lilypond[relative=2,verbatim,quote]
2153 \tweak #'duration-log #1
2158 @code{\tweak} can be used to modify slurs:
2160 @lilypond[verbatim,quote,relative=1]
2161 c-\tweak #'thickness #5 ( d e f)
2165 For the @code{\tweak} command to work, it must
2166 remain immediately adjacent to the object to which it is
2167 to apply after the input file has been converted to a music stream.
2168 Tweaking a whole chord does not do anything since its music event
2169 only acts as a container, and all layout objects are created from events
2170 inside of the @code{EventChord}:
2172 @lilypond[relative=2,verbatim,quote]
2173 \tweak #'color #red c4
2174 \tweak #'color #red <c e>4
2175 <\tweak #'color #red c e>4
2178 The simple @code{\tweak} command cannot be used to modify any object
2179 that is not directly created from the input. In particular
2180 it will not affect stems, automatic
2181 beams or accidentals, since these are generated later by
2182 @code{NoteHead} layout objects rather than by music elements in the
2185 Such indirectly created layout objects can be tweaked using the explicit
2186 form of the @code{\tweak} command:
2188 @lilypond[relative=2,verbatim,quote]
2189 \tweak Stem #'color #red
2190 \tweak Beam #'color #green c8 e
2191 <c e \tweak Accidental #'font-size #-3 ges>4
2194 @code{\tweak} cannot be used to modify clefs or time
2195 signatures, since these become separated from any preceding
2196 @code{\tweak} command in the input stream by the automatic
2197 insertion of extra elements required to specify the context.
2199 Several @code{\tweak} commands may be placed before a
2200 notational element -- all affect it:
2202 @lilypond[verbatim,quote,relative=1]
2204 -\tweak #'style #'dashed-line
2205 -\tweak #'dash-fraction #0.2
2206 -\tweak #'thickness #3
2207 -\tweak #'color #red
2212 The music stream which is generated from a section of an input file,
2213 including any automatically inserted elements, may be examined,
2214 see @rextend{Displaying music expressions}. This may be helpful in
2215 determining what may be modified by a @code{\tweak} command, or
2216 in determining how to adjust the input to make a @code{\tweak}
2221 @rlearning{Tweaking methods}.
2224 @rextend{Displaying music expressions}.
2228 @cindex tweaking control points
2229 @cindex control points, tweaking
2231 The @code{\tweak} command cannot be used to modify the control
2232 points of just one of several ties in a chord, other than the first
2233 one encountered in the input file.
2235 @node set versus override
2236 @subsection @code{\set} vs. @code{\override}
2238 @c TODO -- This section is probably unnecessary now.
2241 We have seen two methods of changing properties: @code{\set} and
2242 @code{\override}. There are actually two different kinds of
2245 @code{fontSize} is a special property: it is equivalent to
2246 entering @code{\override ... #'font-size} for all pertinent
2247 objects. Since this is a common change, the special
2248 property (modified with @code{\set}) was created.
2253 @node Modifying alists
2254 @subsection Modifying alists
2256 Some user-configurable properties are internally represented as
2257 @emph{alists} (association lists), which store pairs of
2258 @emph{keys} and @emph{values}. The structure of an alist is:
2261 '((@var{key1} . @var{value1})
2262 (@var{key2} . @var{value2})
2263 (@var{key3} . @var{value3})
2267 If an alist is a grob property or @code{\paper} variable, its keys
2268 can be modified individually without affecting other keys.
2270 For example, to reduce the space between adjacent staves in a
2271 staff-group, use the @code{staff-staff-spacing} property of the
2272 @code{StaffGrouper} grob. The property is an alist with four
2273 keys: @code{basic-distance}, @code{minimum-distance},
2274 @code{padding}, and @code{stretchability}. The standard settings
2275 for this property are listed in the @qq{Backend} section of the
2276 Internals Reference (see @rinternals{StaffGrouper}):
2279 '((basic-distance . 9)
2280 (minimum-distance . 7)
2282 (stretchability . 5))
2285 One way to bring the staves closer together is by reducing the
2286 value of the @code{basic-distance} key (@code{9}) to match the
2287 value of @code{minimum-distance} (@code{7}). To modify a single
2288 key individually, use a @emph{nested declaration}:
2290 @lilypond[quote,verbatim]
2291 % default space between staves
2293 \new Staff { \clef treble c''1 }
2294 \new Staff { \clef bass c1 }
2297 % reduced space between staves
2298 \new PianoStaff \with {
2299 % this is the nested declaration
2300 \override StaffGrouper #'staff-staff-spacing #'basic-distance = #7
2302 \new Staff { \clef treble c''1 }
2303 \new Staff { \clef bass c1 }
2307 Using a nested declaration will update the specified key (such as
2308 @code{basic-distance} in the above example) without altering any
2309 other keys already set for the same property.
2311 Now suppose we want the staves to be as close as possible without
2312 overlapping. The simplest way to do this is to set all four alist
2313 keys to zero. However, it is not necessary to enter four nested
2314 declarations, one for each key. Instead, the property can be
2315 completely re-defined with one declaration, as an alist:
2317 @lilypond[quote,verbatim]
2318 \new PianoStaff \with {
2319 \override StaffGrouper #'staff-staff-spacing =
2320 #'((basic-distance . 0)
2321 (minimum-distance . 0)
2323 (stretchability . 0))
2325 \new Staff { \clef treble c''1 }
2326 \new Staff { \clef bass c1 }
2330 Note that any keys not explicitly listed in the alist definition
2331 will be reset to their @emph{default-when-unset} values. In the
2332 case of @code{staff-staff-spacing}, any unset key-values would be
2333 reset to zero (except @code{stretchability}, which takes the value
2334 of @code{basic-distance} when unset). Thus the following two
2335 declarations are equivalent:
2338 \override StaffGrouper #'staff-staff-spacing =
2339 #'((basic-distance . 7))
2341 \override StaffGrouper #'staff-staff-spacing =
2342 #'((basic-distance . 7)
2343 (minimum-distance . 0)
2345 (stretchability . 7))
2348 One (possibly unintended) consequence of this is the removal of
2349 any standard settings that are set in an initialization file and
2350 loaded each time an input file is compiled. In the above example,
2351 the standard settings for @code{padding} and
2352 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2353 are reset to their default-when-unset values (zero for both keys).
2354 Defining a property or variable as an alist (of any size) will
2355 always reset all unset key-values to their default-when-unset
2356 values. Unless this is the intended result, it is safer to update
2357 key-values individually with a nested declaration.
2359 @warning{Nested declarations will not work for context property
2360 alists (such as @code{beamExceptions}, @code{keySignature},
2361 @code{timeSignatureSettings}, etc.). These properties can only be
2362 modified by completely re-defining them as alists.}
2365 @node Useful concepts and properties
2366 @section Useful concepts and properties
2371 * Direction and placement::
2372 * Distances and measurements::
2373 * Staff symbol properties::
2375 * Visibility of objects::
2377 * Rotating objects::
2381 @subsection Input modes
2383 The way in which the notation contained within an input file is
2384 interpreted is determined by the current input mode.
2388 This is activated with the @code{\chordmode} command, and causes
2389 input to be interpreted with the syntax of chord notation, see
2390 @ref{Chord notation}. Chords are rendered as notes on a staff.
2392 Chord mode is also activated with the @code{\chords} command.
2393 This also creates a new @code{ChordNames} context and
2394 causes the following input to be interpreted with the syntax of
2395 chord notation and rendered as chord names in the @code{ChordNames}
2396 context, see @ref{Printing chord names}.
2400 This is activated with the @code{\drummode} command, and causes
2401 input to be interpreted with the syntax of drum notation, see
2402 @ref{Basic percussion notation}.
2404 Drum mode is also activated with the @code{\drums} command.
2405 This also creates a new @code{DrumStaff} context and causes the
2406 following input to be interpreted with the syntax of drum notation
2407 and rendered as drum symbols on a drum staff, see @ref{Basic
2408 percussion notation}.
2410 @strong{Figure mode}
2412 This is activated with the @code{\figuremode} command, and causes
2413 input to be interpreted with the syntax of figured bass, see
2414 @ref{Entering figured bass}.
2416 Figure mode is also activated with the @code{\figures} command.
2417 This also creates a new @code{FiguredBass} context and causes the
2418 following input to be interpreted with the figured bass syntax
2419 and rendered as figured bass symbols in the @code{FiguredBass}
2420 context, see @ref{Introduction to figured bass}.
2422 @strong{Fret and tab modes}
2424 There are no special input modes for entering fret and tab symbols.
2426 To create tab diagrams, enter notes or chords in note mode and
2427 render them in a @code{TabStaff} context, see
2428 @ref{Default tablatures}.
2430 To create fret diagrams above a staff, you have two choices.
2431 You can either use the @code{FretBoards} context (see
2432 @ref{Automatic fret diagrams} or you can enter them as a markup
2433 above the notes using the @code{\fret-diagram} command (see
2434 @ref{Fret diagram markups}).
2436 @strong{Lyrics mode}
2438 This is activated with the @code{\lyricmode} command, and causes
2439 input to be interpreted as lyric syllables with optional durations
2440 and associated lyric modifiers, see @ref{Vocal music}.
2442 Lyric mode is also activated with the @code{\addlyrics} command.
2443 This also creates a new @code{Lyrics} context and an implicit
2444 @code{\lyricsto} command which associates the following lyrics
2445 with the preceding music.
2447 @strong{Markup mode}
2449 This is activated with the @code{\markup} command, and causes
2450 input to be interpreted with the syntax of markup, see
2451 @ref{Text markup commands}.
2453 @c silly work-around for texinfo broken-ness
2454 @c (@strong{Note...} causes a spurious cross-reference in Info)
2457 This is the default mode or it may be activated with the
2458 @code{\notemode} command. Input is interpreted as pitches,
2459 durations, markup, etc and typeset as musical notation on a staff.
2461 It is not normally necessary to specify note mode explicitly, but
2462 it may be useful to do so in certain situations, for example if you
2463 are in lyric mode, chord mode or any other mode and want to insert
2464 something that only can be done with note mode syntax.
2466 For example, to indicate dynamic markings for the verses of a
2467 choral pieces it is necessary to enter note mode to interpret
2470 @lilypond[verbatim,relative=2,quote]
2473 \notemode{\set stanza = \markup{ \dynamic f 1. } }
2477 \notemode{\set stanza = \markup{ \dynamic p 2. } }
2484 @node Direction and placement
2485 @subsection Direction and placement
2487 In typesetting music the direction and placement of many items is
2488 a matter of choice. For example, the stems of notes can
2489 be directed up or down; lyrics, dynamics, and other expressive
2490 marks may be placed above or below the staff; text may be aligned
2491 left, right or center; etc. Most of these choices may be left to
2492 be determined automatically by LilyPond, but in some cases it may
2493 be desirable to force a particular direction or placement.
2495 @strong{Articulation direction indicators}
2497 By default some directions are always up or always down (e.g.
2498 dynamics or fermata), while other things can alternate between
2499 up or down based on the stem direction (like slurs or accents).
2501 @c TODO Add table showing these
2503 The default action may be overridden by prefixing the articulation
2504 by a @emph{direction indicator}. Three direction indicators are
2505 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2506 and @code{-} (meaning @qq{use default direction}). The direction
2507 indicator can usually be omitted, in which case @code{-} is assumed,
2508 but a direction indicator is @strong{always} required before
2511 @item @code{\tweak} commands
2512 @item @code{\markup} commands
2513 @item @code{\tag} commands
2514 @item string markups, e.g. -"string"
2515 @item fingering instructions, e.g. @w{@code{-1}}
2516 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2519 Direction indicators affect only the next note:
2521 @lilypond[verbatim,quote,relative=2]
2528 @strong{The direction property}
2530 The position or direction of many layout objects is controlled by the
2531 @code{direction} property.
2533 The value of the @code{direction} property may be set to @code{1},
2534 meaning @qq{up} or @qq{above}, or to @w{@code{-1}}, meaning @qq{down} or
2535 @qq{below}. The symbols @code{UP} and @code{DOWN} may be used instead
2536 of @code{1} and @w{@code{-1}} respectively. The default direction may
2537 be specified by setting @code{direction} to @code{0} or @code{CENTER}.
2538 Alternatively, in many cases predefined commands exist to specify the
2539 direction. These are of the form
2542 @code{\xxxUp}, @code{\xxxDown} or @code{\xxxNeutral}
2546 where @code{\xxxNeutral} means @qq{use the default} direction.
2547 See @rlearning{Within-staff objects}.
2549 In a few cases, arpeggio for example, the value of the @code{direction}
2550 property can specify whether the object is to be placed to the right or
2551 left of the parent. In this case @w{@code{-1}} or @code{LEFT} means
2552 @qq{to the left} and @code{1} or @code{RIGHT} means @qq{to the right}.
2553 @code{0} or @code{CENTER} means @qq{use the default} direction.
2556 These all have side-axis set to #X
2557 AmbitusAccidental - direction has no effect
2559 StanzaNumber - not tried
2560 TrillPitchAccidental - not tried
2561 TrillPitchGroup - not tried
2564 These indications affect all notes until they are canceled.
2566 @lilypond[verbatim,quote,relative=2]
2575 In polyphonic music, it is generally better to specify an explicit
2576 @code{voice} than change an object's direction. For more information.
2577 See @ref{Multiple voices}.
2581 @rlearning{Within-staff objects}.
2584 @ref{Multiple voices}.
2587 @node Distances and measurements
2588 @subsection Distances and measurements
2590 @cindex distances, absolute
2591 @cindex distances, scaled
2598 Distances in LilyPond are of two types: absolute and scaled.
2600 Absolute distances are used for specifying margins, indents, and
2601 other page layout details, and are by default specified in
2602 millimeters. Distances may be specified in other units by
2603 following the quantity by @code{\mm}, @code{\cm},
2604 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2605 an inch). Page layout distances can also be specified in scalable
2606 units (see the following paragraph) by appending
2607 @code{\staff-space} to the quantity. Page layout is described in
2608 detail in @ref{Page layout}.
2610 Scaled distances are always specified in units of the staff-space
2611 or, rarely, the half staff-space. The staff-space is the distance
2612 between two adjacent staff lines. The default value can be changed
2613 globally by setting the global staff size, or it can be overridden
2614 locally by changing the @code{staff-space} property of
2615 @code{StaffSymbol}. Scaled distances automatically scale with any
2616 change to the either the global staff size or the
2617 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2618 automatically only with changes to the global staff size.
2619 The global staff size thus enables the overall size of a rendered
2620 score to be easily varied. For the methods of setting the global
2621 staff size see @ref{Setting the staff size}.
2625 If just a section of a score needs to be rendered to a different
2626 scale, for example an ossia section or a footnote, the global staff
2627 size cannot simply be changed as this would affect the entire score.
2628 In such cases the change in size is made by overriding both the
2629 @code{staff-space} property of @code{StaffSymbol} and the size of
2630 the fonts. A Scheme function, @code{magstep}, is available to
2631 convert from a font size change to the equivalent change in
2632 @code{staff-space}. For an explanation and an example of its use,
2633 see @rlearning{Length and thickness of objects}.
2637 @rlearning{Length and thickness of objects}.
2641 @ref{Setting the staff size}.
2644 @node Staff symbol properties
2645 @subsection Staff symbol properties
2647 @cindex adjusting staff symbol
2648 @cindex drawing staff symbol
2649 @cindex staff symbol, setting of
2651 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2652 @c Need to think of uses for these properties. Eg 'line-positions
2653 @c is used in a snippet to thicken centre line.
2654 @c If retained, add @ref to here in 1.6.2 -td
2656 The vertical position of staff lines and the number of staff lines
2657 can be defined at the same time. As the following example shows,
2658 note positions are not influenced by the staff line positions.
2660 @warning{The @code{'line-positions} property overrides the
2661 @code{'line-count} property. The number of staff lines is
2662 implicitly defined by the number of elements in the list of values
2663 for @code{'line-positions}.}
2665 @lilypond[verbatim,quote,relative=1]
2667 \override StaffSymbol #'line-positions = #'(7 3 0 -4 -6 -7)
2672 The width of a staff can be modified. The units are staff
2673 spaces. The spacing of objects inside the staff is not affected by
2676 @lilypond[verbatim,quote,relative=1]
2678 \override StaffSymbol #'width = #23
2685 @subsection Spanners
2687 Many objects of musical notation extend over several notes or even
2688 several bars. Examples are slurs, beams, tuplet brackets, volta
2689 repeat brackets, crescendi, trills, and glissandi. Such objects
2690 are collectively called @qq{spanners}, and have special properties to control
2691 their appearance and behaviour. Some of these properties are common
2692 to all spanners; others are restricted to a sub-set of the spanners.
2694 All spanners support the @code{spanner-interface}. A few, essentially
2695 those that draw a straight line between the two objects, support in
2696 addition the @code{line-spanner-interface}.
2698 @unnumberedsubsubsec Using the @code{spanner-interface}
2700 This interface provides two properties that apply to several spanners.
2702 @strong{@i{The @code{minimum-length} property}}
2704 The minimum length of the spanner is specified by the
2705 @code{minimum-length} property. Increasing this usually has the
2706 necessary effect of increasing the spacing of the notes between the
2707 two end points. However, this override has no effect on
2708 many spanners, as their length is determined by other considerations.
2709 A few examples where it is effective are shown below.
2719 Works as long as callback is made:
2723 Works not at all for:
2732 @lilypond[verbatim,quote,relative=2]
2735 % increase the length of the tie
2736 -\tweak #'minimum-length #5
2740 @lilypond[verbatim,quote,relative=2]
2742 \compressFullBarRests
2744 % increase the length of the rest bar
2745 \once \override MultiMeasureRest #'minimum-length = #20
2750 @lilypond[verbatim,quote,relative=2]
2752 % increase the length of the hairpin
2753 \override Hairpin #'minimum-length = #20
2757 This override can also be used to increase the length of slurs and
2760 @lilypond[verbatim,quote,relative=2]
2763 -\tweak #'minimum-length #5
2768 -\tweak #'minimum-length #5
2772 For some layout objects, the @code{minimum-length} property becomes
2773 effective only if the @code{set-spacing-rods} procedure is called
2774 explicitly. To do this, the @code{springs-and-rods} property should
2775 be set to @code{ly:spanner::set-spacing-rods}. For example,
2776 the minimum length of a glissando has no effect unless the
2777 @code{springs-and-rods} property is set:
2779 @lilypond[verbatim,quote,relative=1]
2783 % not effective alone
2784 \once \override Glissando #'minimum-length = #20
2787 % effective only when both overrides are present
2788 \once \override Glissando #'minimum-length = #20
2789 \once \override Glissando #'springs-and-rods = #ly:spanner::set-spacing-rods
2793 The same is true of the @code{Beam} object:
2795 @lilypond[verbatim,quote,relative=1]
2796 % not effective alone
2797 \once \override Beam #'minimum-length = #20
2800 % effective only when both overrides are present
2801 \once \override Beam #'minimum-length = #20
2802 \once \override Beam #'springs-and-rods = #ly:spanner::set-spacing-rods
2806 @strong{@i{The @code{to-barline} property}}
2808 The second useful property of the @code{spanner-interface} is
2809 @code{to-barline}. By default this is true, causing hairpins and
2810 other spanners which are terminated on the first note of a measure to
2811 end instead on the immediately preceding bar line. If set to false,
2812 the spanner will extend beyond the bar line and end on the note
2815 @lilypond[verbatim,quote,relative=2]
2816 a \< a a a a \! a a a \break
2817 \override Hairpin #'to-barline = ##f
2818 a \< a a a a \! a a a
2821 This property is not effective for all spanners. For example,
2822 setting it to @code{#t} has no effect on slurs or phrasing slurs
2823 or on other spanners for which terminating on the bar line would
2826 @unnumberedsubsubsec Using the @code{line-spanner-interface}
2828 Objects which support the @code{line-spanner-interface} include
2831 @item @code{DynamicTextSpanner}
2832 @item @code{Glissando}
2833 @item @code{TextSpanner}
2834 @item @code{TrillSpanner}
2835 @item @code{VoiceFollower}
2838 The routine responsible for drawing the stencils for these spanners is
2839 @code{ly:line-interface::print}. This routine determines the
2840 exact location of the two end points and draws a line
2841 between them, in the style requested. The locations of the two
2842 end points of the spanner are computed on-the-fly, but it is
2843 possible to override their Y-coordinates. The
2844 properties which need to be specified are nested
2845 two levels down within the property hierarchy, but the syntax of
2846 the @code{\override} command is quite simple:
2848 @lilypond[relative=2,quote,verbatim]
2850 \once \override Glissando #'(bound-details left Y) = #3
2851 \once \override Glissando #'(bound-details right Y) = #-2
2855 The units for the @code{Y} property are @code{staff-space}s,
2856 with the center line of the staff being the zero point.
2857 For the glissando, this is the value for @code{Y} at the
2858 X-coordinate corresponding to the center point of each note head,
2859 if the line is imagined to be extended to there.
2861 If @code{Y} is not set, the value is computed from the vertical
2862 position of the corresponding attachment point of the spanner.
2864 In case of a line break, the values for the end points are
2865 specified by the @code{left-broken} and @code{right-broken}
2866 sub-lists of @code{bound-details}. For example:
2868 @lilypond[relative=2,ragged-right,verbatim,quote]
2869 \override Glissando #'breakable = ##t
2870 \override Glissando #'(bound-details right-broken Y) = #-3
2871 c1 \glissando \break
2876 A number of further properties of the @code{left} and
2877 @code{right} sub-lists of the @code{bound-details} property
2878 may be modified in the same way as @code{Y}:
2882 This sets the Y-coordinate of the end point, in @code{staff-space}s
2883 offset from the staff center line. By default, it is the center of
2884 the bound object, so a glissando points to the vertical center of
2887 For horizontal spanners, such as text spanners and trill spanners,
2888 it is hardcoded to 0.
2891 This determines where the line starts and ends in the X-direction,
2892 relative to the bound object. So, a value of @w{@code{-1}} (or
2893 @code{LEFT}) makes the line start/end at the left side of the note
2894 head it is attached to.
2897 This is the absolute X-coordinate of the end point. It is usually
2898 computed on the fly, and overriding it has little useful effect.
2901 Line spanners may have symbols at the beginning or end, which is
2902 contained in this sub-property. This is for internal use; it is
2903 recommended that @code{text} be used instead.
2906 This is a markup that is evaluated to yield the stencil. It is used
2907 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
2909 @lilypond[quote,ragged-right,relative=2,verbatim]
2910 \override TextSpanner #'(bound-details left text)
2911 = \markup { \small \bold Slower }
2912 c2\startTextSpan b c a\stopTextSpan
2915 @item stencil-align-dir-y
2916 @item stencil-offset
2917 Without setting one of these, the stencil is simply put at the
2918 end-point, centered on the line, as defined by the @code{X} and
2919 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
2920 or @code{stencil-offset} will move the symbol at the edge vertically
2921 relative to the end point of the line:
2923 @lilypond[relative=1,quote,verbatim]
2924 \override TextSpanner
2925 #'(bound-details left stencil-align-dir-y) = #-2
2926 \override TextSpanner
2927 #'(bound-details right stencil-align-dir-y) = #UP
2929 \override TextSpanner
2930 #'(bound-details left text) = #"ggg"
2931 \override TextSpanner
2932 #'(bound-details right text) = #"hhh"
2933 c4^\startTextSpan c c c \stopTextSpan
2936 Note that negative values move the text @emph{up}, contrary to the
2937 effect that might be expected, as a value of @w{@code{-1}} or
2938 @code{DOWN} means align the @emph{bottom} edge of the text with
2939 the spanner line. A value of @code{1} or @code{UP} aligns
2940 the top edge of the text with the spanner line.
2943 Setting this sub-property to @code{#t} produces an arrowhead at the
2947 This sub-property controls the space between the specified
2948 end point of the line and the actual end. Without padding, a
2949 glissando would start and end in the center of each note head.
2953 The music function @code{\endSpanners} terminates the spanner
2954 which starts on the immediately following note prematurely. It
2955 is terminated after exactly one note, or at the following bar line
2956 if @code{to-barline} is true and a bar line occurs before the next
2959 @lilypond[verbatim,quote,ragged-right,relative=2]
2961 c2 \startTextSpan c2 c2
2966 When using @code{\endSpanners} it is not necessary to close
2967 \startTextSpan with \stopTextSpan, nor is it necessary to close
2968 hairpins with @code{\!}.
2971 Internals Reference:
2972 @rinternals{TextSpanner},
2973 @rinternals{Glissando},
2974 @rinternals{VoiceFollower},
2975 @rinternals{TrillSpanner},
2976 @rinternals{line-spanner-interface}.
2979 @node Visibility of objects
2980 @subsection Visibility of objects
2982 @cindex objects, visibility of
2983 @cindex grobs, visibility of
2984 @cindex visibility of objects
2986 There are four main ways in which the visibility of layout objects
2987 can be controlled: their stencil can be removed, they can be made
2988 transparent, they can be colored white, or their
2989 @code{break-visibility} property can be overridden. The first
2990 three apply to all layout objects; the last to just a few -- the
2991 @emph{breakable} objects. The Learning Manual introduces these
2992 four techniques, see @rlearning{Visibility and color of objects}.
2994 There are also a few other techniques which are specific to
2995 certain layout objects. These are covered under Special
2999 * Removing the stencil::
3000 * Making objects transparent::
3001 * Painting objects white::
3002 * Using break-visibility::
3003 * Special considerations::
3007 @node Removing the stencil
3008 @unnumberedsubsubsec Removing the stencil
3010 @cindex stencil, removing
3012 Every layout object has a stencil property. By default this is set
3013 to the specific function which draws that object. If this property
3014 is overridden to @code{#f} no function will be called and the object
3015 will not be drawn. The default action can be recovered with
3018 @lilypond[quote,verbatim,relative=1]
3020 \override Score.BarLine #'stencil = ##f
3022 \revert Score.BarLine #'stencil
3026 @node Making objects transparent
3027 @unnumberedsubsubsec Making objects transparent
3029 @cindex transparent, making objects
3031 Every layout object has a transparent property which by default is
3032 set to @code{#f}. If set to @code{#t} the object still occupies
3033 space but is made invisible.
3035 @lilypond[quote,verbatim,relative=2]
3037 \once \override NoteHead #'transparent = ##t
3041 @node Painting objects white
3042 @unnumberedsubsubsec Painting objects white
3044 @cindex objects, coloring
3045 @cindex coloring objects
3047 @cindex printing order
3048 @cindex overwriting objects
3049 @cindex objects, overwriting
3050 @cindex grobs, overwriting
3052 Every layout object has a color property which by default is set
3053 to @code{black}. If this is overridden to @code{white} the object
3054 will be indistinguishable from the white background. However,
3055 if the object crosses other objects the color of the crossing
3056 points will be determined by the order in which they are drawn,
3057 and this may leave a ghostly image of the white object, as shown
3060 @lilypond[quote,verbatim,relative=2]
3061 \override Staff.Clef #'color = #white
3065 This may be avoided by changing the order of printing the objects.
3066 All layout objects have a @code{layer} property which should be set
3067 to an integer. Objects with the lowest value of @code{layer} are
3068 drawn first, then objects with progressively higher values are drawn,
3069 so objects with higher values overwrite objects with lower values.
3070 By default most objects are assigned a @code{layer} value of
3071 @code{1}, although a few objects, including @code{StaffSymbol} and
3072 @code{BarLine}, are assigned a value of @code{0}. The order of
3073 printing objects with the same value of @code{layer} is indeterminate.
3075 In the example above the white clef, with a default @code{layer}
3076 value of @code{1}, is drawn after the staff lines (default
3077 @code{layer} value @code{0}), so overwriting them. To change this,
3078 the @code{Clef} object must be given in a lower value of
3079 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
3081 @lilypond[quote,verbatim,relative=2]
3082 \override Staff.Clef #'color = #white
3083 \override Staff.Clef #'layer = #-1
3087 @node Using break-visibility
3088 @unnumberedsubsubsec Using break-visibility
3090 @c TODO Add making other objects breakable
3092 @cindex break-visibility
3094 Most layout objects are printed only once, but some like
3095 bar lines, clefs, time signatures and key signatures, may need
3096 to be printed twice when a line break occurs -- once at the end
3097 of the line and again at the start of the next line. Such
3098 objects are called @emph{breakable}, and have a property, the
3099 @code{break-visibility} property to control their visibility
3100 at the three positions in which they may appear -- at the
3101 start of a line, within a line if they are changed, and at the
3102 end of a line if a change takes place there.
3104 For example, the time signature
3105 by default will be printed at the start of the first line, but
3106 nowhere else unless it changes, when it will be printed at the
3107 point at which the change occurs. If this change occurs at the
3108 end of a line the new time signature will be printed at the start
3109 of the next line and a cautionary time signature will be printed
3110 at the end of the previous line as well.
3112 This behaviour is controlled by the @code{break-visibility}
3113 property, which is explained in
3114 @c Leave this ref on a newline - formats incorrectly otherwise -td
3115 @rlearning{Visibility and color of objects}. This property takes
3116 a vector of three booleans which, in order, determine whether the
3117 object is printed at the end of, within the body of, or at the
3118 beginning of a line. Or to be more precise, before a line break,
3119 where there is no line break, or after a line break.
3121 Alternatively, these eight combinations may be specified
3122 by pre-defined functions, defined in @file{scm/output-lib.scm},
3123 where the last three columns indicate whether the layout objects
3124 will be visible in the positions shown at the head of the columns:
3126 @multitable {@code{begin-of-line-invisible}} {@code{'#(#t #t #t)}} {Before} {At no} {After}
3127 @headitem Function @tab Vector @tab Before @tab At no @tab After
3128 @headitem form @tab form @tab break @tab break @tab break
3130 @item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
3131 @item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
3132 @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
3133 @item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
3134 @item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
3135 @item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
3136 @item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
3137 @item @code{all-invisible} @tab @code{'#(#f #f #f)} @tab no @tab no @tab no
3140 The default settings of @code{break-visibility} depend on the
3141 layout object. The following table shows all the layout objects
3142 of interest which are affected by @code{break-visibility} and the
3143 default setting of this property:
3145 @multitable @columnfractions .3 .3 .4
3147 @headitem Layout object @tab Usual context @tab Default setting
3149 @c omit Ambitus as it appears not to be affected by break-visibility -td
3150 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
3151 @item @code{BarLine} @tab @code{Score} @tab calculated
3152 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
3153 @c omit the following item until it can be explained -td
3154 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
3155 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3156 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
3157 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
3158 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3159 @c omit KeyCancellation until it can be explained -td
3160 @c @item @code{KeyCancellation} @tab ?? @tab @code{begin-of-line-invisible}
3161 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
3162 @c omit LeftEdge until it can be explained -td
3163 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
3164 @item @code{OctavateEight} @tab @code{Staff} @tab @code{begin-of-line-visible}
3165 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
3166 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
3170 The example below shows the use of the vector form to control the
3171 visibility of bar lines:
3173 @lilypond[quote,verbatim,relative=1,ragged-right]
3176 % Remove bar line at the end of the current line
3177 \once \override Score.BarLine #'break-visibility = #'#(#f #t #t)
3183 Although all three components of the vector used to override
3184 @code{break-visibility} must be present, not all of them are
3185 effective with every layout object, and some combinations may
3186 even give errors. The following limitations apply:
3189 @item Bar lines cannot be printed at start of line.
3190 @item A bar number cannot be printed at the start of the first
3191 line unless it is set to be different from 1.
3192 @item Clef -- see below
3193 @item Double percent repeats are either all printed or all
3194 suppressed. Use begin-of line-invisible to print and
3195 all-invisible to suppress.
3196 @item Key signature -- see below
3197 @item OctavateEight -- see below
3200 @node Special considerations
3201 @unnumberedsubsubsec Special considerations
3203 @strong{@emph{Visibility following explicit changes}}
3205 @cindex key signature, visibility following explicit change
3206 @cindex explicitKeySignatureVisibility
3207 @cindex clef, visibility following explicit change
3208 @cindex explicitClefVisibility
3210 The @code{break-visibility} property controls the visibility of
3211 key signatures and changes of clef only at the start of lines,
3212 i.e. after a break. It has no effect on the visibility of the
3213 key signature or clef following an explicit key change or an
3214 explicit clef change within or at the end of a line. In the
3215 following example the key signature following the explicit change
3216 to B-flat major is still visible, even though @code{all-invisible}
3219 @lilypond[quote,verbatim,relative=1,ragged-right]
3222 % Try to remove all key signatures
3223 \override Staff.KeySignature #'break-visibility = #all-invisible
3231 The visibility of such explicit key signature and clef changes is
3232 controlled by the @code{explicitKeySignatureVisibility} and
3233 @code{explicitClefVisibility} properties. These are the equivalent
3234 of the @code{break-visibility} property and both take a vector of
3235 three booleans or the predefined functions listed above, exactly like
3236 @code{break-visibility}. Both are properties of the Staff context,
3237 not the layout objects themselves, and so they are set using the
3238 @code{\set} command. Both are set by default to @code{all-visible}.
3239 These properties control only the visibility of key signatures and
3240 clefs resulting from explicit changes and do not affect key
3241 signatures and clefs at the beginning of lines;
3242 @code{break-visibility} must still be overridden in the appropriate
3243 object to remove these.
3245 @lilypond[quote,verbatim,relative=1,ragged-right]
3248 \set Staff.explicitKeySignatureVisibility = #all-invisible
3249 \override Staff.KeySignature #'break-visibility = #all-invisible
3256 @strong{@emph{Visibility of cautionary accidentals}}
3258 To remove the cautionary accidentals printed at an explicit key
3259 change, set the Staff context property @code{printKeyCancellation}
3262 @lilypond[quote,verbatim,relative=1,ragged-right]
3265 \set Staff.explicitKeySignatureVisibility = #all-invisible
3266 \set Staff.printKeyCancellation = ##f
3267 \override Staff.KeySignature #'break-visibility = #all-invisible
3274 With these overrides only the accidentals before the notes remain
3275 to indicate the change of key.
3277 @c TODO Add visibility of cautionary accidentals before notes
3279 @strong{@emph{Automatic bars}}
3281 @cindex automaticBars
3282 @cindex bar lines, suppressing
3284 As a special case, the printing of bar lines can also be turned off
3285 by setting the @code{automaticBars} property in the Score context.
3286 If set to @code{#f}, bar lines will not be printed automatically;
3287 they must be explicitly created with a @code{\bar} command. Unlike
3288 the @code{\cadenzaOn} predefined command, measures are still counted.
3289 Bar generation will resume according to that count if this property
3290 is later set to @code{#t}. When set to @code{#f}, line breaks can
3291 occur only at explicit @code{\bar} commands.
3295 @strong{@emph{Octavated clefs}}
3297 @cindex octavated clefs, visibility of
3298 @cindex visibility of octavated clefs
3299 @cindex clefs, visibility of octavation
3301 The small octavation symbol on octavated clefs is produced by the
3302 @code{OctavateEight} layout object. Its visibility is automatically
3303 inherited from the @code{Clef} object, so it is not necessary to apply
3304 any required @code{break-visibility} overrides to the @code{OctavateEight}
3305 layout objects to suppress octavation symbols for invisible clefs.
3307 For explicit clef changes, the @code{explicitClefVisibility}
3308 property controls both the clef symbol and any octavation symbol
3313 @rlearning{Visibility and color of objects}.
3317 @subsection Line styles
3319 Some performance indications, e.g., @i{rallentando} and
3320 @i{accelerando} and @i{trills} are written as text and are
3321 extended over many measures with lines, sometimes dotted or wavy.
3323 These all use the same routines as the glissando for drawing the
3324 texts and the lines, and tuning their behavior is therefore also
3325 done in the same way. It is done with a spanner, and the routine
3326 responsible for drawing the spanners is
3327 @code{ly:line-interface::print}. This routine determines the
3328 exact location of the two @i{span points} and draws a line
3329 between them, in the style requested.
3331 Here is an example showing the different line styles available,
3332 and how to tune them.
3334 @lilypond[relative=2,ragged-right,verbatim,quote]
3336 \once \override Glissando #'style = #'dashed-line
3338 \override Glissando #'style = #'dotted-line
3340 \override Glissando #'style = #'zigzag
3342 \override Glissando #'style = #'trill
3346 The locations of the end-points of the spanner are computed
3347 on-the-fly for every graphic object, but it is possible to
3351 @lilypond[relative=2,ragged-right,verbatim,quote]
3353 \once \override Glissando #'(bound-details right Y) = #-2
3357 The value for @code{Y} is set to @w{@code{-2}} for the right end
3358 point. The left side may be similarly adjusted by specifying
3359 @code{left} instead of @code{right}.
3361 If @code{Y} is not set, the value is computed from the vertical
3362 position of the left and right attachment points of the spanner.
3364 Other adjustments of spanners are possible, for details, see
3367 @node Rotating objects
3368 @subsection Rotating objects
3370 Both layout objects and elements of markup text can be rotated by
3371 any angle about any point, but the method of doing so differs.
3374 * Rotating layout objects::
3378 @node Rotating layout objects
3379 @unnumberedsubsubsec Rotating layout objects
3381 @cindex rotating objects
3382 @cindex objects, rotating
3384 All layout objects which support the @code{grob-interface} can be
3385 rotated by setting their @code{rotation} property. This takes a
3386 list of three items: the angle of rotation counter-clockwise,
3387 and the x and y coordinates of the point relative to the object's
3388 reference point about which the rotation is to be performed. The
3389 angle of rotation is specified in degrees and the coordinates in
3392 The angle of rotation and the coordinates of the rotation point must
3393 be determined by trial and error.
3395 @cindex hairpins, angled
3396 @cindex angled hairpins
3398 There are only a few situations where the rotation of layout
3399 objects is useful; the following example shows one situation where
3402 @lilypond[quote,verbatim,relative=1]
3404 \override Hairpin #'rotation = #'(20 -1 0)
3408 @node Rotating markup
3409 @unnumberedsubsubsec Rotating markup
3411 All markup text can be rotated to lie at any angle by prefixing it
3412 with the @code{\rotate} command. The command takes two arguments:
3413 the angle of rotation in degrees counter-clockwise and the text to
3414 be rotated. The extents of the text are not rotated: they take
3415 their values from the extremes of the x and y coordinates of the
3416 rotated text. In the following example the
3417 @code{outside-staff-priority} property for text is set to @code{#f}
3418 to disable the automatic collision avoidance, which would push some
3419 of the text too high.
3421 @lilypond[quote,verbatim,relative=1]
3422 \override TextScript #'outside-staff-priority = ##f
3423 g4^\markup { \rotate #30 "a G" }
3424 b^\markup { \rotate #30 "a B" }
3425 des^\markup { \rotate #30 "a D-Flat" }
3426 fis^\markup { \rotate #30 "an F-Sharp" }
3429 @node Advanced tweaks
3430 @section Advanced tweaks
3432 This section discusses various approaches to fine tuning the
3433 appearance of the printed score.
3436 * Aligning objects::
3437 * Vertical grouping of grobs::
3438 * Modifying stencils::
3439 * Modifying shapes::
3440 * Unpure-pure containers::
3445 @rlearning{Tweaking output},
3446 @rlearning{Other sources of information}.
3449 @ref{Explaining the Internals Reference},
3450 @ref{Modifying properties}.
3453 @rextend{Interfaces for programmers}.
3456 @file{scm/define-grobs.scm}.
3459 @rlsr{Tweaks and overrides}.
3461 Internals Reference:
3462 @rinternals{All layout objects}.
3465 @node Aligning objects
3466 @subsection Aligning objects
3468 Graphical objects which support the @code{self-alignment-interface}
3469 and/or the @code{side-position-interface} can be aligned to a previously
3470 placed object in a variety of ways. For a list of these objects, see
3471 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3473 All graphical objects have a reference point, a horizontal extent and a
3474 vertical extent. The horizontal extent is a pair of numbers
3475 giving the displacements from the reference point of the left and
3476 right edges, displacements to the left being negative. The vertical
3477 extent is a pair of numbers giving the displacement from the reference
3478 point to the bottom and top edges, displacements down being negative.
3480 An object's position on a staff is given by the values of the
3481 @code{X-offset} and @code{Y-offset} properties. The value of
3482 @code{X-offset} gives the displacement from the X coordinate of
3483 the reference point of the parent object, and the value of
3484 @code{Y-offset} gives the displacement from the center line of the
3485 staff. The values of @code{X-offset} and @code{Y-offset} may
3486 be set directly or may be set to be calculated by procedures in order
3487 to achieve alignment with the parent object.
3489 @warning{Many objects have special positioning considerations which
3490 cause any setting of @code{X-offset} or @code{Y-offset} to be
3491 ignored or modified, even though the object supports the
3492 @code{self-alignment-interface}. Overriding the @code{X-offset}
3493 or @code{Y-offset} properties to a fixed value causes the respective
3494 @code{self-alignment} property to be disregarded.}
3496 For example, an accidental can be repositioned vertically by setting
3497 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3499 Rehearsal marks may be aligned with breakable objects such as bar
3500 lines, clef symbols, time signature symbols and key signatures. There
3501 are special properties to be found in the @code{break-aligned-interface}
3502 for positioning rehearsal marks on such objects.
3506 @ref{Using the break-alignable-interface}.
3509 @rextend{Callback functions}.
3512 * Setting X-offset and Y-offset directly::
3513 * Using the side-position-interface::
3514 * Using the self-alignment-interface::
3515 * Using the break-alignable-interface::
3518 @node Setting X-offset and Y-offset directly
3519 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3521 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3522 properties of many objects. The following example shows three
3523 notes with the default fingering position and the positions with @code{X-offset}
3524 and @code{Y-offset} modified.
3526 @lilypond[verbatim,quote,relative=2]
3529 -\tweak #'X-offset #0
3530 -\tweak #'Y-offset #0
3533 -\tweak #'X-offset #-1
3534 -\tweak #'Y-offset #1
3540 @node Using the side-position-interface
3541 @unnumberedsubsubsec Using the @code{side-position-interface}
3543 An object which supports the @code{side-position-interface} can be
3544 placed next to its parent object so that
3545 the specified edges of the two objects touch. The object may be
3546 placed above, below, to the right or to the left of the parent.
3547 The parent cannot be specified; it is determined by the order of
3548 elements in the input stream. Most objects have the associated
3549 note head as their parent.
3551 The values of the @code{side-axis} and @code{direction} properties
3552 determine where the object is to be placed, as follows:
3554 @c TODO add an example of each to the table
3556 @multitable @columnfractions .3 .3 .3
3557 @headitem @code{side-axis} @tab @code{direction} @tab
3558 @headitem property @tab property @tab Placement
3560 @item @code{0} @tab @code{-1} @tab left
3561 @item @code{0} @tab @code{1} @tab right
3562 @item @code{1} @tab @code{-1} @tab below
3563 @item @code{1} @tab @code{1} @tab above
3567 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3568 the procedure @code{ly:side-position-interface::x-aligned-side}.
3569 This procedure will return the correct value of @code{X-offset} to
3570 place the object to the left or right side of the parent according
3571 to value of @code{direction}.
3573 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3574 the procedure @code{ly:side-position-interface::y-aligned-side}.
3575 This procedure will return the correct value of @code{Y-offset} to
3576 place the object to the top or bottom of the parent according
3577 to value of @code{direction}.
3579 @c TODO Add examples
3581 @node Using the self-alignment-interface
3582 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3584 @emph{Self-aligning objects horizontally}
3586 The horizontal alignment of an object which supports the
3587 @code{self-alignment-interface} is controlled by the value of
3588 the @code{self-alignment-X} property, provided the object's
3589 @code{X-offset} property is set to
3590 @code{ly:self-alignment-interface::x-aligned-on-self}.
3591 @code{self-alignment-X} may be given any
3592 real value, in units of half the total X extent of the
3593 object. Negative values move the object to the right, positive
3594 to the left. A value of @code{0} centers the object on the
3595 reference point of its parent, a value of @w{@code{-1}} aligns the
3596 left edge of the object on the reference point of its parent,
3597 and a value of @code{1} aligns the right edge of the object on the
3598 reference point of its parent. The symbols @code{LEFT},
3599 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3600 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3602 Normally the @code{\override} command would be used to modify the
3603 value of @code{self-alignment-X}, but the @code{\tweak} command
3604 can be used to separately align several annotations on a single
3607 @lilypond[quote,verbatim,relative=1]
3609 -\tweak #'self-alignment-X #-1
3611 -\tweak #'self-alignment-X #0
3613 -\tweak #'self-alignment-X #RIGHT
3615 -\tweak #'self-alignment-X #-2.5
3616 ^"aligned further to the right"
3619 @emph{Self-aligning objects vertically}
3621 Objects may be aligned vertically in an analogous way to aligning
3622 them horizontally if the @code{Y-offset} property is set to
3623 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3624 other mechanisms are often involved in vertical alignment: the
3625 value of @code{Y-offset} is just one variable taken into account.
3626 This may make adjusting the value of some objects tricky.
3627 The units are just half the vertical extent of the object, which
3628 is usually quite small, so quite large numbers may be required.
3629 A value of @w{@code{-1}} aligns the lower edge of the object with
3630 the reference point of the parent object, a value of @code{0}
3631 aligns the center of the object with the reference point of the
3632 parent, and a value of @code{1} aligns the top edge of the object
3633 with the reference point of the parent. The symbols @code{DOWN},
3634 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3635 @code{0}, and @code{1}, respectively.
3637 @emph{Self-aligning objects in both directions}
3639 By setting both @code{X-offset} and @code{Y-offset}, an object may
3640 be aligned in both directions simultaneously.
3642 The following example shows how to adjust a fingering mark so
3643 that it nestles close to the note head.
3645 @lilypond[quote,verbatim,relative=2]
3647 -\tweak #'self-alignment-X #0.5 % move horizontally left
3648 -\tweak #'Y-offset #ly:self-alignment-interface::y-aligned-on-self
3649 -\tweak #'self-alignment-Y #-1 % move vertically up
3654 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
3656 @c Cannot document as they do not seem to operate consistently on all objects -td
3657 @c TODO investigate further
3659 The @code{aligned-on-parent} procedures are used in the same way
3660 as the @code{aligned-on-self} procedures, they difference being
3661 that they permit an object to be aligned with the @emph{edges} of
3662 the parent rather than the parent's reference point. The following
3663 example shows the difference:
3667 @lilypond[verbatim,quote]
3673 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
3675 @c Cannot document as they do not seem to operate consistently on all objects -td
3676 @c TODO investigate further
3680 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
3682 @node Using the break-alignable-interface
3683 @unnumberedsubsubsec Using the @code{break-alignable-interface}
3685 @cindex align to objects
3686 @cindex break-align-symbols
3688 Rehearsal marks and bar numbers may be aligned with notation
3689 objects other than bar lines. These objects include @code{ambitus},
3690 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
3691 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
3692 @code{time-signature}.
3694 By default, rehearsal marks and bar numbers will be horizontally
3695 centered above the object:
3697 @lilypond[verbatim,quote,relative=1]
3698 % The rehearsal mark will be centered above the Clef
3699 \override Score.RehearsalMark #'break-align-symbols = #'(clef)
3704 % The rehearsal mark will be centered above the Time Signature
3705 \override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
3711 % The rehearsal mark will be centered above the Breath Mark
3712 \override Score.RehearsalMark #'break-align-symbols = #'(breathing-sign)
3721 A list of possible target alignment objects may be specified. If
3722 some of the objects are invisible at that point due to the setting
3723 of @code{break-visibility} or the explicit visibility settings for
3724 keys and clefs, the rehearsal mark or bar number is aligned to the
3725 first object in the list which is visible. If no objects in the
3726 list are visible the object is aligned to the bar line. If the bar
3727 line is invisible the object is aligned to the place where the bar
3730 @lilypond[verbatim,quote,relative=1]
3731 % The rehearsal mark will be centered above the Key Signature
3732 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3737 % The rehearsal mark will be centered above the Clef
3738 \set Staff.explicitKeySignatureVisibility = #all-invisible
3739 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3744 % The rehearsal mark will be centered above the Bar Line
3745 \set Staff.explicitKeySignatureVisibility = #all-invisible
3746 \set Staff.explicitClefVisibility = #all-invisible
3747 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature clef)
3754 The alignment of the rehearsal mark relative to the notation object
3755 can be changed, as shown in the following example. In a score with
3756 multiple staves, this setting should be done for all the staves.
3758 @lilypond[verbatim,quote,relative=1]
3759 % The RehearsalMark will be centered above the Key Signature
3760 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3766 % The RehearsalMark will be aligned with the left edge of the Key Signature
3767 \once \override Score.KeySignature #'break-align-anchor-alignment = #LEFT
3771 % The RehearsalMark will be aligned with the right edge of the Key Signature
3772 \once \override Score.KeySignature #'break-align-anchor-alignment = #RIGHT
3778 The rehearsal mark can also be offset to the right or left of the left
3779 edge by an arbitrary amount. The units are staff-spaces:
3781 @lilypond[verbatim,quote,relative=1]
3782 % The RehearsalMark will be aligned with the left edge of the Key Signature
3783 % and then shifted right by 3.5 staff-spaces
3784 \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
3785 \once \override Score.KeySignature #'break-align-anchor = #3.5
3789 % The RehearsalMark will be aligned with the left edge of the Key Signature
3790 % and then shifted left by 2 staff-spaces
3791 \once \override Score.KeySignature #'break-align-anchor = #-2
3798 @node Vertical grouping of grobs
3799 @subsection Vertical grouping of grobs
3801 @c TODO Expand this section
3803 The VerticalAlignment and VerticalAxisGroup grobs work together.
3804 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
3805 etc. VerticalAlignment then vertically aligns the different grobs
3806 grouped together by VerticalAxisGroup. There is usually only one
3807 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
3811 @node Modifying stencils
3812 @subsection Modifying stencils
3814 All layout objects have a @code{stencil} property which is part of
3815 the @code{grob-interface}. By default, this property is usually
3816 set to a function specific to the object that is tailor-made to
3817 render the symbol which represents it in the output. For example,
3818 the standard setting for the @code{stencil} property of the
3819 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
3821 The standard symbol for any object can be replaced by modifying the
3822 @code{stencil} property to reference a different, specially-written,
3823 procedure. This requires a high level of knowledge of the internal
3824 workings of LilyPond, but there is an easier way which can often
3825 produce adequate results.
3827 This is to set the @code{stencil} property to the procedure which
3828 prints text -- @code{ly:text-interface::print} -- and to add a
3829 @code{text} property to the object which is set to contain the
3830 markup text which produces the required symbol. Due to the
3831 flexibility of markup, much can be achieved -- see in particular
3832 @ref{Graphic notation inside markup}.
3834 The following example demonstrates this by changing the note head
3835 symbol to a cross within a circle.
3837 @lilypond[verbatim,quote]
3839 \once \override NoteHead #'stencil = #ly:text-interface::print
3840 \once \override NoteHead #'text = \markup {
3842 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
3843 \musicglyph #"noteheads.s2cross"
3851 Any of the glyphs in the feta Font can be supplied to the
3852 @code{\musicglyph} markup command -- see @ref{The Feta font}.
3854 @c TODO Add inserting eps files or ref to later
3856 @c TODO Add inserting Postscript or ref to later
3860 @ref{Graphic notation inside markup},
3861 @ref{Formatting text},
3862 @ref{Text markup commands},
3863 @ref{The Feta font}.
3866 @node Modifying shapes
3867 @subsection Modifying shapes
3870 * Modifying ties and slurs::
3873 @node Modifying ties and slurs
3874 @unnumberedsubsubsec Modifying ties and slurs
3876 @cindex slurs, modifying
3877 @cindex ties, modifying
3878 @cindex Bézier curves, control points
3879 @cindex control points, Bézier curves
3881 Ties, slurs and phrasing slurs are drawn as third-order Bézier
3882 curves. If the shape of the tie or slur which is calculated
3883 automatically is not optimum, the shape may be modified manually by
3884 explicitly specifying the four control points required to define
3885 a third-order Bézier curve.
3887 Third-order or cubic Bézier curves are defined by four control
3888 points. The first and fourth control points are precisely the
3889 starting and ending points of the curve. The intermediate two
3890 control points define the shape. Animations showing how the curve
3891 is drawn can be found on the web, but the following description
3892 may be helpful. The curve starts from the first control point
3893 heading directly towards the second, gradually bending over to
3894 head towards the third and continuing to bend over to head towards
3895 the fourth, arriving there travelling directly from the third
3896 control point. The curve is entirely contained in the
3897 quadrilateral defined by the four control points.
3899 Here is an example of a case where the tie is not optimum, and
3900 where @code{\tieDown} would not help.
3902 @lilypond[verbatim,quote,relative=1]
3906 { r4 <g c,> <g c,> <g c,> }
3910 One way of improving this tie is to manually modify its control
3913 The coordinates of the Bézier control points are specified in units
3914 of staff-spaces. The X@tie{}coordinate is relative to the reference
3915 point of the note to which the tie or slur is attached, and the
3916 Y@tie{}coordinate is relative to the staff center line. The
3917 coordinates are entered as a list of four pairs of decimal numbers
3918 (reals). One approach is to estimate the coordinates of the two
3919 end points, and then guess the two intermediate points. The optimum
3920 values are then found by trial and error.
3922 It is useful to remember that a symmetric curve requires symmetric
3923 control points, and that Bézier curves have the useful property that
3924 transformations of the curve such as translation, rotation and
3925 scaling can be achieved by applying the same transformation to the
3926 curve's control points.
3928 For the example above the following override gives a satisfactory
3929 tie. Note the placement -- it has to be immediately before the note
3930 to which the start of the tie (or slur) is attached.
3932 @lilypond[verbatim,quote,relative=1]
3936 #'control-points = #'((1 . -1) (3 . 0.6) (12.5 . 0.6) (14.5 . -1))
3940 { r4 <g c,> <g c,> <g c,> }
3945 It is not possible to modify shapes of ties or slurs by changing
3946 the @code{control-points} property if there are multiple ties or slurs
3947 at the same musical moment -- the @code{\tweak} command will also not
3948 work in this case. However, the @code{tie-configuration} property of
3949 @code{TieColumn} can be overridden to set start line and direction as
3953 Internals Reference:
3954 @rinternals{TieColumn}.
3956 @cindex Scheme, pure containers
3957 @cindex Scheme, unpure containers
3958 @cindex pure containers, Scheme
3959 @cindex unpure containers, Scheme
3960 @cindex horizontal spacing, overriding
3963 @node Unpure-pure containers
3964 @subsection Unpure-pure containers
3966 Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
3967 calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
3968 Scheme function instead of a literal (i.e. a number or pair).
3970 For certain grobs, the @code{Y-extent} is based on the @code{stencil}
3971 property, overriding the stencil property of one of these will
3972 require an additional @code{Y-extent} override with an unpure-pure
3973 container. When a function overrides a @code{Y-offset} and/or
3974 @code{Y-extent} it is assumed that this will trigger line breaking
3975 calculations too early during compilation. So the function is not
3976 evaluated at all (usually returning a value of @samp{0} or
3977 @samp{'(0 . 0)}) which can result in collisions. A @q{pure} function
3978 will not affect properties, objects or grob suicides and therefore will
3979 always have its Y-axis-related evaluated correctly.
3981 Currently, there are about thirty functions that are already considered
3982 @q{pure} and Unpure-pure containers are a way to set functions not on
3983 this list as @q{pure}. The @q{pure} function is evaluated @emph{before}
3984 any line-breaking and so the horizontal spacing can be adjusted
3985 @q{in time}. The @q{unpure} function is then evaluated @emph{after}
3988 @warning{As it is difficult to always know which functions are on this
3989 list we recommend that any @q{pure} functions you create do not use
3990 @code{Beam} or @code{VerticalAlignment} grobs.}
3992 An unpure-pure container is constructed as follows;
3994 @code{(ly:make-unpure-pure-container f0 f1)}
3996 where @code{f0} is a function taking @var{n} arguments (@var{n >= 1})
3997 and the first argument must always be the grob. This is the function
3998 that gives the actual result. @var{f1} is the function being labeled
3999 as @q{pure} that takes @var{n + 2} arguments. Again, the first argument
4000 must always still be the grob but the second and third are @q{start}
4001 and @q{end} arguments.
4003 @var{start} and @var{end} are, for all intents and purposes, dummy
4004 values that only matter for @code{Spanners} (i.e @code{Hairpin} or
4005 @code{Beam}), that can return different height estimations based on a
4006 starting and ending column.
4008 The rest are the other arguments to the first function (which
4009 may be none if @var{n = 1}).
4011 The results of the second function are used as an approximation of the
4012 value needed which is then used by the first function to get the real
4013 value which is then used for fine-tuning much later during the spacing
4016 @lilypond[verbatim,quote,ragged-right]
4017 #(define (square-line-circle-space grob)
4018 (let* ((pitch (ly:event-property (ly:grob-property grob 'cause) 'pitch))
4019 (notename (ly:pitch-notename pitch)))
4020 (if (= 0 (modulo notename 2))
4021 (make-circle-stencil 0.5 0.0 #t)
4022 (make-filled-box-stencil '(0 . 1.0)
4025 squareLineCircleSpace = {
4026 \override NoteHead #'stencil = #square-line-circle-space
4029 smartSquareLineCircleSpace = {
4030 \squareLineCircleSpace
4031 \override NoteHead #'Y-extent =
4032 #(ly:make-unpure-pure-container
4033 ly:grob::stencil-height
4034 (lambda (grob start end) (ly:grob::stencil-height grob)))
4037 \new Voice \with { \remove "Stem_engraver" }
4039 \squareLineCircleSpace
4041 \smartSquareLineCircleSpace
4046 In the first measure, without the unpure-pure container, the spacing
4047 engine does not know the width of the note head and lets it collide with
4048 the accidentals. In the second measure, with unpure-pure containers,
4049 the spacing engine knows the width of the note heads and avoids the
4050 collision by lengthening the line accordingly.
4052 Usually for simple calculations nearly-identical functions for both the
4053 @q{unpure} and @q{pure} parts can be used, by only changing the number
4054 of arguments passed to, and the scope of, the function.
4056 @warning{If a function is labeled as @q{pure} and it turns out not to
4057 be, the results can be unexpected.}
4060 @node Using music functions
4061 @section Using music functions
4063 @c TODO -- add @seealso, etc. to these subsections
4065 Where tweaks need to be reused with different music expressions,
4066 it is often convenient to make the tweak part of a @emph{music
4067 function}. In this section, we discuss only @emph{substitution}
4068 functions, where the object is to substitute a variable into a
4069 piece of LilyPond input code. Other more complex functions are
4070 described in @rextend{Music functions}.
4073 * Substitution function syntax::
4074 * Substitution function examples::
4077 @node Substitution function syntax
4078 @subsection Substitution function syntax
4080 Making a function that substitutes a variable into LilyPond
4081 code is easy. The general form of these functions is
4085 #(define-music-function
4086 (parser location @var{arg1} @var{arg2} @dots{})
4087 (@var{type1?} @var{type2?} @dots{})
4089 @var{@dots{}music@dots{}}
4096 @multitable @columnfractions .33 .66
4097 @item @code{@var{argN}}
4098 @tab @var{n}th argument
4100 @item @code{@var{typeN?}}
4101 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
4102 must return @code{#t}.
4104 @item @code{@var{@dots{}music@dots{}}}
4105 @tab normal LilyPond input, using @code{$} (in places where only
4106 Lilypond constructs are allowed) or @code{#} (to use it as a Scheme
4107 value or music function argument) to reference arguments
4111 The @code{parser} and @code{location} arguments are mandatory, and
4112 are used in some advanced situations as described in the
4113 @q{Extending} manual (see @rextend{Music functions}). For
4114 substitution functions, just be sure to include them.
4116 The list of type predicates is also required. Some of the most
4117 common type predicates used in music functions are:
4121 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
4133 For a list of available type predicates, see
4134 @ref{Predefined type predicates}. User-defined type predicates
4139 @ref{Predefined type predicates}.
4142 @rextend{Music functions}.
4145 @file{lily/music-scheme.cc},
4147 @file{scm/lily.scm}.
4150 @node Substitution function examples
4151 @subsection Substitution function examples
4153 This section introduces some substitution function examples.
4154 These are not intended to be exhaustive, but rather to demonstrate
4155 some of the possibilities of simple substitution functions.
4157 In the first example, a function is defined that simplifies
4158 setting the padding of a TextScript:
4160 @lilypond[quote,verbatim,ragged-right]
4162 #(define-music-function
4163 (parser location padding)
4166 \once \override TextScript #'padding = #padding
4170 c4^"piu mosso" b a b
4172 c4^"piu mosso" d e f
4174 c4^"piu mosso" fis a g
4178 In addition to numbers, we can use music expressions such
4179 as notes for arguments to music functions:
4181 @lilypond[quote,verbatim,ragged-right]
4183 #(define-music-function
4184 (parser location note)
4187 \tweak NoteHead #'stencil #ly:text-interface::print
4188 \tweak NoteHead #'text
4189 \markup \musicglyph #"custodes.mensural.u0"
4190 \tweak Stem #'stencil ##f
4194 \relative c' { c4 d e f \custosNote g }
4197 Substitution functions with multiple arguments can be defined:
4199 @lilypond[quote,verbatim,ragged-right]
4201 #(define-music-function
4202 (parser location padding tempotext)
4205 \once \override Score.MetronomeMark #'padding = #padding
4206 \tempo \markup { \bold #tempotext }
4210 \tempo \markup { "Low tempo" }
4212 \tempoPadded #4.0 "High tempo"
4217 @c TODO: add appropriate @@ref's here.