1 @c -*- coding: utf-8; mode: texinfo; documentlanguage: it -*-
4 Translation of GIT committish: 28add695953862ef4a87f9fbeadd1d02dc299244
6 When revising a translation, copy the HEAD committish of the
7 version that you are working on. For details, see the Contributors'
8 Guide, node Updating translation committishes..
11 @c Translators: Federico Bruni
12 @c Translation checkers:
16 @node Modifica delle impostazioni predefinite
17 @chapter Modifica delle impostazioni predefinite
18 @translationof Changing defaults
20 The purpose of LilyPond's design is to provide the finest quality
21 output by default. Nevertheless, it may happen that you need to
22 change this default layout. The layout is controlled through a large
23 number of @q{knobs and switches} collectively called @q{properties}.
24 A tutorial introduction to accessing and modifying these properties
25 can be found in the Manuale di apprendimento, see @rlearning{Modifica dell'output}.
26 This should be read first. This chapter covers similar ground, but
27 in a style more appropriate to a reference manual.
29 @cindex Internals Reference
30 @cindex Guida al funzionamento interno
32 The definitive description of the controls available for tuning can
33 be found in a separate document: @rinternalsnamed{Top,the Internals
34 Reference}. That manual lists all the variables, functions and
35 options available in LilyPond. It is written as a HTML document,
37 @c leave the @uref as one long line.
38 @uref{http://@/lilypond@/.org/@/doc/@/stable/@/Documentation/@/internals/,on@/-line},
39 and is also included with the LilyPond documentation package.
41 Internally, LilyPond uses Scheme (a LISP dialect) to provide
42 infrastructure. Overriding layout decisions in effect accesses the
43 program internals, which requires Scheme input. Scheme elements are
44 introduced in a @file{.ly} file with the hash
45 mark@tie{}@code{#}.@footnote{@rextend{Scheme tutorial}, contains a
46 short tutorial on entering numbers, lists, strings, and symbols in
51 * Contesti di interpretazione::
52 * Come funziona la Guida al funzionamento interno::
53 * Modifica delle proprietà::
54 * Proprietà e concetti utili::
56 * Uso delle funzioni musicali::
60 @node Contesti di interpretazione
61 @section Contesti di interpretazione
62 @translationof Interpretation contexts
64 This section describes what contexts are, and how to modify them.
67 * Contexts explained::
68 * Creating and referencing contexts::
69 * Keeping contexts alive::
70 * Modifying context plug-ins::
71 * Changing context default settings::
72 * Defining new contexts::
73 * Context layout order::
77 Manuale di apprendimento:
78 @rlearning{Contesti e incisori}.
81 @file{ly/engraver-init.ly},
82 @file{ly/performer-init.ly}.
85 @rlsr{Contexts and engravers}.
87 Guida al funzionamento interno:
88 @rinternals{Contexts},
89 @rinternals{Engravers and Performers}.
92 @node Contexts explained
93 @subsection Contexts explained
96 @c TODO Rethink and rewrite
98 >> > > - list of contexts: my *danger unmaintainable*
99 >> > > alarm just went off. I'm
101 I knew it would... And leaving out some of them is perfectly fine
103 I do think that a list like this, with the main contexts and a
105 description of what they do (perhaps also with a note about what
107 behavior is associated with each of them, but this may be
109 should be there, and then we could simply list the remaining ones
111 further explanation and with links to the IR.
114 @c TODO Improve layout, order and consistency of wording -td
116 @c TODO Add introduction which explains contexts in generality -td
118 @c TODO Describe propagation of property values -td
120 Contexts are arranged hierarchically:
123 * Output definitions - blueprints for contexts::
124 * Score - the master of all contexts::
125 * Top-level contexts - staff containers::
126 * Intermediate-level contexts - staves::
127 * Bottom-level contexts - voices::
130 @node Output definitions - blueprints for contexts
131 @unnumberedsubsubsec Output definitions - blueprints for contexts
133 This section explains the relevance of output definitions when
134 working with contexts. Examples for actual output definitions are
135 given later (see @ref{Changing all contexts of the same type}).
137 @cindex output definitions
139 While music written in a file may refer to context types and
140 names, contexts are created only when the music is actually being
141 interpreted. LilyPond interprets music under control of an
142 @q{output definition} and may do so for several different output
143 definitions, resulting in different output. The output definition
144 relevant for printing music is specified using @code{\layout}.
147 A much simpler output definition used for producing Midi output is
148 specified using @code{\midi}. Several other output definitions
149 are used by LilyPond internally, like when using the part combiner
150 (@ref{Automatic part combining}) or creating music quotes
151 (@ref{Quoting other voices}).
153 Output definitions define the relation between contexts as well as
154 their respective default settings. While most changes will
155 usually be made inside of a @code{\layout} block, Midi-related
156 settings will only have an effect when made within a @code{\midi}
159 @funindex autoBeaming
160 Some settings affect several outputs: for example, if
161 @code{autoBeaming} is turned off in some context, beams count as
162 melismata for the purpose of matching music to lyrics as described
163 in @ref{Automatic syllable durations}. This matching is done both
164 for printed output as well as for Midi. If changes made to
165 @code{autoBeaming} within a context definition of a @code{\layout}
166 block are not repeated in the corresponding @code{\midi} block,
167 lyrics and music will get out of sync in Midi.
171 @file{ly/engraver-init.ly}.
172 @file{ly/performer-init.ly}.
174 @node Score - the master of all contexts
175 @unnumberedsubsubsec Score - the master of all contexts
177 This is the top level notation context. No other context can
178 contain a Score context. By default the Score context handles
179 the administration of time signatures and makes sure that items
180 such as clefs, time signatures, and key-signatures are aligned
183 A Score context is instantiated implicitly when a
184 @code{\score @{@dots{}@}} block is processed.
186 @node Top-level contexts - staff containers
187 @unnumberedsubsubsec Top-level contexts - staff containers
189 @strong{@emph{StaffGroup}}
191 Groups staves while adding a bracket on the left side, grouping
192 the staves together. The bar lines of the contained staves are
193 connected vertically. @code{StaffGroup} only consists of a collection
194 of staves, with a bracket in front and spanning bar lines.
196 @strong{@emph{ChoirStaff}}
198 Identical to @code{StaffGroup} except that the bar lines of the
199 contained staves are not connected vertically.
201 @strong{@emph{GrandStaff}}
203 A group of staves, with a brace on the left side, grouping the
204 staves together. The bar lines of the contained staves are
205 connected vertically.
207 @strong{@emph{PianoStaff}}
209 Just like @code{GrandStaff}, but with support for instrument names
210 to the left of each system.
212 @node Intermediate-level contexts - staves
213 @unnumberedsubsubsec Intermediate-level contexts - staves
215 @strong{@emph{Staff}}
217 Handles clefs, bar lines, keys, accidentals. It can contain
218 @code{Voice} contexts.
220 @strong{@emph{RhythmicStaff}}
222 Like @code{Staff} but for printing rhythms. Pitches are ignored
223 when engraving; the notes are printed on one line. The MIDI
224 rendition retains pitches unchanged.
226 @strong{@emph{TabStaff}}
228 Context for generating tablature. By default lays the music
229 expression out as a guitar tablature, printed on six lines.
231 @strong{@emph{DrumStaff}}
233 Handles typesetting for percussion. Can contain @code{DrumVoice}
235 @strong{@emph{VaticanaStaff}}
237 Same as @code{Staff}, except that it is designed for typesetting
238 a piece in gregorian style.
240 @strong{@emph{MensuralStaff}}
242 Same as @code{Staff}, except that it is designed for typesetting
243 a piece in mensural style.
245 @node Bottom-level contexts - voices
246 @unnumberedsubsubsec Bottom-level contexts - voices
248 Voice-level contexts initialise certain properties and start
249 appropriate engravers. A bottom-level context is one without
250 @code{defaultchild}. While it is possible to let it
251 accept/@/contain subcontexts, they can only be created and entered
254 @strong{@emph{Voice}}
256 Corresponds to a voice on a staff. This context handles the
257 conversion of dynamic signs, stems, beams, super- and sub-scripts,
258 slurs, ties, and rests. You have to instantiate this explicitly
259 if you require multiple voices on the same staff.
261 @strong{@emph{VaticanaVoice}}
263 Same as @code{Voice}, except that it is designed for typesetting
264 a piece in gregorian style.
266 @strong{@emph{MensuralVoice}}
268 Same as @code{Voice}, with modifications for typesetting a piece in
271 @strong{@emph{Lyrics}}
273 Corresponds to a voice with lyrics. Handles the printing of a
274 single line of lyrics.
276 @strong{@emph{DrumVoice}}
278 The voice context used in a percussion staff.
280 @strong{@emph{FiguredBass}}
282 The context in which @code{BassFigure} objects are created from
283 input entered in @code{\figuremode} mode.
285 @strong{@emph{TabVoice}}
287 The voice context used within a @code{TabStaff} context. Usually
288 left to be created implicitly.
290 @strong{@emph{CueVoice}}
292 A voice context used to render notes of a reduced size, intended
293 primarily for adding cue notes to a staff, see @ref{Formatting
294 cue notes}. Usually left to be created implicitly.
296 @strong{@emph{ChordNames}}
298 Typesets chord names.
303 Then the following, which I don't know what to do with:
305 * GregorianTranscriptionVoice
306 * GregorianTranscriptionStaff
309 Engraves fretboards from chords. Not easy... Not
311 There is now some documentation on FretBoards in the NR, under
312 instrument-specific notation -- cds.
317 Hard coded entry point for LilyPond. Cannot be tuned.
319 Silently discards all musical information given to this
324 @node Creating and referencing contexts
325 @subsection Creating and referencing contexts
330 @cindex referencing contexts
331 @cindex Contexts, creating and referencing
333 LilyPond will create lower-level contexts automatically if a music
334 expression is encountered before a suitable context exists, but this
335 is usually successful only for simple scores or music fragments like
336 the ones in the documentation. For more complex scores it is
337 advisable to specify all contexts explicitly with either the
338 @code{\new} or @code{\context} command. The syntax of
339 these two commands is very similar:
342 [\new | \context] @var{Context} [ = @var{name}] [@var{music-expression}]
346 where either @code{\new} or @code{\context} may be specified.
347 @var{Context} is the type of context which is to be created,
348 @var{name} is an optional name to be given to the particular context
349 being created and @var{music-expression} is a single music expression
350 that is to be interpreted by the engravers and performers in this
353 The @code{\new} prefix without a name is commonly used to create
354 scores with many staves:
356 @lilypond[quote,verbatim]
358 \new Staff \relative {
359 % leave the Voice context to be created implicitly
362 \new Staff \relative {
369 and to place several voices into one staff:
371 @lilypond[quote,verbatim]
373 \new Voice \relative {
377 \new Voice \relative {
385 @code{\new} should always be used to specify unnamed contexts.
387 The difference between @code{\new} and @code{\context} is in the
392 @code{\new} with or without a name will always create a fresh,
393 distinct, context, even if one with the same name already exists:
395 @lilypond[quote,verbatim]
397 \new Voice = "A" \relative {
401 \new Voice = "A" \relative {
409 @code{\context} with a name specified will create a distinct context
410 only if a context of the same type with the same name in the same
411 context hierarchy does not already exist. Otherwise it will be taken
412 as a reference to that previously created context, and its music
413 expression will be passed to that context for interpretation.
415 One application of named contexts is in separating the score layout
416 from the musical content. Either of these two forms is valid:
418 @lilypond[quote,verbatim]
432 \context Voice = "one" {
437 \context Voice = "two" {
446 @lilypond[quote,verbatim]
451 \context Voice = "one" {
454 \context Voice = "two" {
460 \context Voice = "one" {
465 \context Voice = "two" {
475 Alternatively, variables may be employed to similar effect. See
476 @rlearning{Organizzare i brani con le variabili}.
479 @code{\context} with no name will match the first of any previously
480 created contexts of the same type in the same context heirarchy,
481 even one that has been given a name, and its music expression will be
482 passed to that context for interpretation. This form is rarely
483 useful. However, @code{\context} with no name and no music expression
484 is used to set the context in which a Scheme procedure specified with
485 @code{\applyContext} is executed:
488 \new Staff \relative @{
491 \applyContext #(lambda (ctx)
493 (display (ly:context-current-moment ctx)))
500 A context must be named if it is to be referenced later, for example
501 when lyrics are associated with music:
504 \new Voice = "tenor" @var{music}
506 \new Lyrics \lyricsto "tenor" @var{lyrics}
510 For details of associating lyrics with music see
511 @ref{Automatic syllable durations}.
513 The properties of all contexts of a particular type can be modified
514 in a @code{\layout} block (with a different syntax), see
515 @ref{Changing all contexts of the same type}. This construct also
516 provides a means of keeping layout instructions separate from the
517 musical content. If a single context is to be modified, a @code{\with}
518 block must be used, see @ref{Changing just one specific context}.
521 Manuale di apprendimento:
522 @rlearning{Organizzare i brani con le variabili}.
524 Guida alla notazione:
525 @ref{Changing just one specific context},
526 @ref{Automatic syllable durations}.
529 @node Keeping contexts alive
530 @subsection Keeping contexts alive
532 @cindex contexts, keeping alive
533 @cindex contexts, lifetime
535 Contexts are usually terminated at the first musical moment in
536 which they have nothing to do. So @code{Voice} contexts die as
537 soon as they contain no events; @code{Staff} contexts die as soon
538 as all the @code{Voice} contexts within them contain no events; etc.
539 This can cause difficulties if earlier contexts which have died
540 have to be referenced, for example, when changing staves with
541 @code{\change} commands, associating lyrics with a voice with
542 @code{\lyricsto} commands, or when adding further musical events to
545 There is an exception to this general rule: inside of an
546 @code{@{@dots{}@}} construct (sequential music), the construct's
547 notion of the ``current context'' will descend whenever an element
548 of the sequence ends in a subcontext of the previous current
549 context. This avoids spurious creation of implicit contexts in a
550 number of situations but means that the first context descended
551 into will be kept alive until the end of the expression.
553 In contrast, the contexts of a @code{<<@dots{}>>} construct's
554 (simultaneous music) expression are not carried forth, so
555 enclosing a context creating command in an extra pair of
556 @code{<<@dots{}>>} will keep the context from persisting through
557 all of the enclosing @code{@{@dots{}@}} sequence.
559 Any context can be kept alive by ensuring it has something to do at
560 every musical moment. @code{Staff} contexts are kept alive by
561 ensuring one of their voices is kept alive. One way of doing this
562 is to add spacer rests to a voice in parallel with the real music.
563 These need to be added to every @code{Voice} context which needs to
564 be kept alive. If several voices are to be used sporadically it is
565 safest to keep them all alive rather than attempting to rely on the
566 exceptions mentioned above.
568 In the following example, both voice A and voice B are kept alive
569 in this way for the duration of the piece:
571 @lilypond[quote,verbatim]
572 musicA = \relative { d''4 d d d }
573 musicB = \relative { g'4 g g g }
576 \new Voice = "A" { s1*5 } % Keep Voice "A" alive for 5 bars
577 \new Voice = "B" { s1*5 } % Keep Voice "B" alive for 5 bars
582 \context Voice = "A" {
586 \context Voice = "B" {
590 \context Voice = "A" { \musicA }
591 \context Voice = "B" { \musicB }
592 \context Voice = "A" { \musicA }
603 @cindex lyrics, aligning with sporadic melody
605 The following example shows how a sporadic melody line with lyrics
606 might be written using this approach. In a real situation the
607 melody and accompaniment would consist of several different
610 @lilypond[quote,verbatim]
611 melody = \relative { a'4 a a a }
612 accompaniment = \relative { d'4 d d d }
613 words = \lyricmode { These words fol -- low the mel -- o -- dy }
616 \new Staff = "music" {
618 \new Voice = "melody" {
620 s1*4 % Keep Voice "melody" alive for 4 bars
623 \new Voice = "accompaniment" {
628 \context Voice = "melody" { \melody }
629 \context Voice = "accompaniment" { \accompaniment }
631 \context Voice = "accompaniment" { \accompaniment }
633 \context Voice = "melody" { \melody }
634 \context Voice = "accompaniment" { \accompaniment }
639 \new Lyrics \with { alignAboveContext = #"music" }
640 \lyricsto "melody" { \words }
645 An alternative way, which may be better in many circumstances, is
646 to keep the melody line alive by simply including spacer notes to
647 line it up correctly with the accompaniment:
649 @lilypond[quote,verbatim]
656 accompaniment = \relative {
662 words = \lyricmode { These words fol -- low the mel -- o -- dy }
666 \new Staff = "music" {
668 \new Voice = "melody" {
672 \new Voice = "accompaniment" {
678 \new Lyrics \with { alignAboveContext = #"music" }
679 \lyricsto "melody" { \words }
685 @node Modifying context plug-ins
686 @subsection Modifying context plug-ins
688 @c TODO Should this be Modifying engravers or Modifying contexts?
690 Notation contexts (like @code{Score} and @code{Staff}) not only store
691 properties, they also contain plug-ins called @q{engravers} that create
692 notation elements. For example, the @code{Voice} context contains a
693 @code{Note_heads_engraver} and the @code{Staff} context contains a
696 For a full a description of each plug-in, see
698 @rinternals{Engravers and Performers}.
701 Guida al funzionamento interno @expansion{} Translation @expansion{} Engravers.
703 Every context described in
705 @rinternals{Contexts}
708 Guida al funzionamento interno @expansion{} Translation @expansion{} Context.
710 lists the engravers used for that context.
713 It can be useful to shuffle around these plug-ins. This is done by
714 starting a new context with @code{\new} or @code{\context}, and
720 \new @var{context} \with @{
728 @emph{@dots{}music@dots{}}
733 where the @dots{} should be the name of an engraver. Here is a simple
734 example which removes @code{Time_signature_engraver} and
735 @code{Clef_engraver} from a @code{Staff} context,
737 @lilypond[quote,verbatim]
739 \new Staff \relative {
743 \remove "Time_signature_engraver"
744 \remove "Clef_engraver"
751 In the second staff there are no time signature or clef symbols. This
752 is a rather crude method of making objects disappear since it will affect
753 the entire staff. This method also influences the spacing, which may or
754 may not be desirable. More sophisticated methods of blanking objects
755 are shown in @rlearning{Visibilità e colore degli oggetti}.
757 The next example shows a practical application. Bar lines and time
758 signatures are normally synchronized across the score. This is done
759 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
760 This plug-in keeps an administration of time signature, location
761 within the measure, etc. By moving these engraver from @code{Score} to
762 @code{Staff} context, we can have a score where each staff has its own
765 @cindex polymetric scores
766 @cindex time signature, multiple
768 @lilypond[quote,verbatim]
772 \consists "Timing_translator"
773 \consists "Default_bar_line_engraver"
780 \consists "Timing_translator"
781 \consists "Default_bar_line_engraver"
791 \remove "Timing_translator"
792 \remove "Default_bar_line_engraver"
800 The order in which the engravers are specified is the order in
801 which they are called to carry out their processing. Usually the
802 order in which the engravers are specified does not matter, but in
803 a few special cases the order is important, for example where one
804 engraver writes a property and another reads it, or where one
805 engraver creates a grob and another must process it.
807 The following orderings are important:
811 the @code{Bar_engraver} must normally be first,
814 the @code{New_fingering_engraver} must come before the
815 @code{Script_column_engraver},
818 the @code{Timing_translator} must come before the
819 @code{Bar_number_engraver}.
825 @file{ly/engraver-init.ly}.
828 @node Changing context default settings
829 @subsection Changing context default settings
831 @cindex default context properties, changing
832 @cindex context properties, changing defaults
834 Context and grob properties can be changed with @code{\set}
835 and @code{\override} commands, as described in
836 @ref{Modifying properties}. These commands create music events,
837 making the changes take effect at the point in time the music
840 In contrast, this section explains how to change the @emph{default}
841 values of context and grob properties at the time the context is
842 created. There are two ways of doing this. One modifies the default
843 values in all contexts of a particular type, the other modifies the
844 default values in just one particular instance of a context.
847 * Changing all contexts of the same type::
848 * Changing just one specific context::
849 * Order of precedence::
852 @node Changing all contexts of the same type
853 @unnumberedsubsubsec Changing all contexts of the same type
855 @cindex \context in \layout block
859 The default context settings which are to be used for typesetting in
860 @code{Score}, @code{Staff}, @code{Voice} and other contexts may be
861 specified in a @code{\context} block within any @code{\layout}
864 Settings for Midi output as opposed to typesetting will have to be
865 separately specified in @code{\midi} blocks (see @ref{Output
866 definitions - blueprints for contexts}).
868 The @code{\layout} block should be placed within the @code{\score}
869 block to which it is to apply, after the music.
875 [context settings for all Voice contexts]
879 [context settings for all Staff contexts]
884 The following types of settings may be specified:
888 An @code{\override} command, but with the context name omitted
890 @lilypond[quote,verbatim]
893 a'4^"Thicker stems" a a a
899 \override Stem.thickness = #4.0
906 Directly setting a context property
908 @lilypond[quote,verbatim]
911 a'4^"Smaller font" a a a
924 A predefined command such as @code{\dynamicUp} or a music
925 expression like @code{\accidentalStyle dodecaphonic}
927 @lilypond[quote,verbatim]
930 a'4^"Dynamics above" a a a
940 \accidentalStyle dodecaphonic
947 A user-defined variable containing a @code{\with} block; for details
948 of the @code{\with} block see
949 @ref{Changing just one specific context}.
951 @lilypond[quote,verbatim]
952 StaffDefaults = \with {
959 a'4^"Smaller font" a a a
974 Property-setting commands can be placed in a @code{\layout} block
975 without being enclosed in a @code{\context} block. Such settings
976 are equivalent to including the same property-setting commands at
977 the start of every context of the type specified. If no context
978 is specified @emph{every} bottom-level context is affected, see
979 @ref{Bottom-level contexts - voices}. The syntax of a
980 property-setting command in a @code{\layout} block is the same as
981 the same command written in the music stream.
983 @lilypond[quote,verbatim]
987 a'4^"Smaller font" a a a
992 \accidentalStyle dodecaphonic
994 \override Voice.Stem.thickness = #4.0
1000 @node Changing just one specific context
1001 @unnumberedsubsubsec Changing just one specific context
1006 The context properties of just one specific context instance can be
1007 changed in a @code{\with} block. All other context instances of the
1008 same type retain the default settings built into LilyPond and modified
1009 by any @code{\layout} block within scope. The @code{\with} block
1010 must be placed immediately after the @code{\new} @var{context-type}
1014 \new Staff \with @{ [context settings for this context instance only] @}
1020 Since such a @q{context modification} is specified inside of
1021 music, it will affect @emph{all} outputs (typesetting @emph{and}
1022 Midi) as opposed to changes within an output definition.
1024 The following types of settings may be specified:
1028 An @code{\override} command, but with the context name omitted
1030 @lilypond[quote,verbatim]
1033 \new Voice \with { \override Stem.thickness = #4.0 }
1036 a'4^"Thick stems" a a a
1045 Directly setting a context property
1047 @lilypond[quote,verbatim]
1052 a'4^"Default font" a a a
1056 \new Staff \with { fontSize = #-4 }
1059 a'4^"Smaller font" a a a
1068 A predefined command such as @code{\dynamicUp}
1070 @lilypond[quote,verbatim]
1076 a'4^"Dynamics below" a a a
1081 \new Staff \with { \accidentalStyle dodecaphonic }
1083 \new Voice \with { \dynamicUp }
1086 a'4^"Dynamics above" a a a
1097 @node Order of precedence
1098 @unnumberedsubsubsec Order of precedence
1100 The value of a property which applies at a particular time is
1101 determined as follows:
1105 if an @code{\override} or @code{\set} command in the input stream is
1106 in effect that value is used,
1109 otherwise the default value taken from a @code{\with} statement
1110 on the context initiation statement is used,
1113 otherwise the default value taken from the most recent appropriate
1114 @code{\context} block in the @code{\layout} or @code{\midi} blocks
1118 otherwise the LilyPond built-in default is used.
1122 Manuale di apprendimento:
1123 @rlearning{Modificare le proprietà di contesto}.
1125 Guida alla notazione:
1126 @ref{Contexts explained},
1127 @ref{Bottom-level contexts - voices},
1128 @ref{The set command},
1129 @ref{The override command},
1130 @ref{The layout block,,The @code{@bs{}layout} block}.
1133 @node Defining new contexts
1134 @subsection Defining new contexts
1136 @cindex contexts, defining new
1137 @cindex engravers, including in contexts
1152 Specific contexts, like @code{Staff} and @code{Voice}, are made from
1153 simple building blocks. It is possible to create new types of
1154 contexts with different combinations of engraver plug-ins.
1156 The next example shows how to build a different type of
1157 @code{Voice} context from scratch. It will be similar to
1158 @code{Voice}, but only prints centered slash note heads. It can be used
1159 to indicate improvisation in jazz pieces,
1161 @lilypond[quote,ragged-right]
1162 \layout { \context {
1164 \type "Engraver_group"
1165 \consists "Note_heads_engraver"
1166 \consists "Rhythmic_column_engraver"
1167 \consists "Text_engraver"
1168 \consists "Pitch_squash_engraver"
1169 squashedPosition = #0
1170 \override NoteHead.style = #'slash
1175 \accepts "ImproVoice"
1179 a'4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1180 c4 c^"undress" c_"while playing :)" c }
1186 These settings are defined within a @code{\context} block inside a
1187 @code{\layout} block,
1197 In the following discussion, the example input shown should go in place
1198 of the @dots{} in the previous fragment.
1200 First it is necessary to define a name for the new context:
1206 Since it is similar to the @code{Voice} context, we want commands that
1207 work in (existing) @code{Voice} contexts to continue working. This is
1208 achieved by giving the new context an alias of @code{Voice},
1214 The context will print notes and instructive texts, so we need to add
1215 the engravers which provide this functionality, plus the engraver which
1216 groups notes, stems and rests which occur at the same musical moment
1220 \consists "Note_heads_engraver"
1221 \consists "Text_engraver"
1222 \consists "Rhythmic_column_engraver"
1225 The note heads should all be placed on the center line,
1228 \consists "Pitch_squash_engraver"
1229 squashedPosition = #0
1232 The @code{Pitch_squash_engraver} modifies note heads (created
1233 by the @code{Note_heads_engraver}) and sets their vertical
1234 position to the value of @code{squashedPosition}, in this
1235 case@tie{}@code{0}, the center line.
1237 The notes look like a slash, and have no stem,
1240 \override NoteHead.style = #'slash
1244 All these plug-ins have to communicate under the control of the
1245 context. The mechanisms with which contexts communicate are
1246 established by declaring the context @code{\type}. Within a
1247 @code{\layout} block, most contexts will be of type
1248 @code{Engraver_group}. Some special contexts and contexts in
1249 @code{\midi} blocks use other context types. Copying and
1250 modifying an existing context definition will also fill in the
1251 type. Since this example creates a definition from scratch, it
1252 needs to be specified explicitly.
1255 \type "Engraver_group"
1258 Put together, we get
1263 \type "Engraver_group"
1264 \consists "Note_heads_engraver"
1265 \consists "Text_engraver"
1266 \consists "Rhythmic_column_engraver"
1267 \consists "Pitch_squash_engraver"
1268 squashedPosition = #0
1269 \override NoteHead.style = #'slash
1276 Contexts form hierarchies. We want to place the @code{ImproVoice}
1277 context within the @code{Staff} context, just like normal @code{Voice}
1278 contexts. Therefore, we modify the @code{Staff} definition with the
1279 @code{\accepts} command,
1288 @funindex \inherit-acceptability
1289 Often when reusing an existing context definition, the resulting
1290 context can be used anywhere where the original context would have
1296 \inherit-acceptability @var{to} @var{from}
1301 will arrange to have contexts of type @var{to} accepted by all
1302 contexts also accepting @var{from}. For example, using
1307 \inherit-acceptability "ImproVoice" "Voice"
1312 will add an @code{\accepts} for @code{ImproVoice} to both
1313 @code{Staff} and @code{RhythmicStaff} definitions.
1316 The opposite of @code{\accepts} is @code{\denies},
1317 which is sometimes needed when reusing existing context definitions.
1319 Arranging the required pieces into a @code{\layout} block leaves
1328 \inherit-acceptability "ImproVoice" "Voice"
1332 Then the output at the start of this subsection can be entered as
1340 c c_"while playing :)"
1346 To complete this example, changes affecting the context hierarchy
1347 should be repeated in a @code{\midi} block so that Midi output
1348 depends on the same context relations.
1352 Guida al funzionamento interno:
1353 @rinternals{Note_heads_engraver},
1354 @rinternals{Text_engraver},
1355 @rinternals{Rhythmic_column_engraver},
1356 @rinternals{Pitch_squash_engraver}.
1359 @node Context layout order
1360 @subsection Context layout order
1362 @cindex contexts, layout order
1366 Contexts are normally positioned in a system from top to bottom
1367 in the order in which they are encountered in the input file. When
1368 contexts are nested, the outer context will include inner nested
1369 contexts as specified in the input file, provided the inner contexts
1370 are included in the outer context's @qq{accepts} list. Nested
1371 contexts which are not included in the outer context's @qq{accepts}
1372 list will be repositioned below the outer context rather than nested
1375 The @qq{accepts} list of a context can be changed with the
1376 @code{\accepts} or @code{\denies} commands. @code{\accepts} adds a
1377 context to the @qq{accepts} list and @code{\denies} removes a context
1380 For example, a square-braced staff group is not usually found within a
1381 curved-braced staff with connecting staff bars, and a @code{GrandStaff}
1382 does not accept a @code{StaffGroup} inside it by default.
1384 @lilypond[verbatim,quote]
1391 \new Staff { \set Staff.instrumentName = bottom f'1 }
1396 However, by using the @code{\accepts} command, @code{StaffGroup} can be
1397 added to the @code{GrandStaff} context:
1399 @lilypond[verbatim,quote]
1406 \new Staff { \set Staff.instrumentName = bottom f'1 }
1411 \accepts "StaffGroup"
1417 @code{\denies} is mainly used when a new context is being based on
1418 another, but the required nesting differs. For example, the
1419 @code{VaticanaStaff} context is based on the @code{Staff} context, but
1420 with the @code{VaticanaVoice} context substituted for the @code{Voice}
1421 context in the @qq{accepts} list.
1423 @cindex contexts, implicit
1424 @cindex implicit contexts
1425 @funindex \defaultchild
1427 Note that a context will be silently created implicitly if a
1428 command is encountered when there is no suitable context available
1431 Within a context definition, the type of subcontext to be
1432 implicitly created is specified using @code{\defaultchild}. A
1433 number of music events require a @samp{Bottom} context: when such
1434 an event is encountered, subcontexts are created recursively until
1435 reaching a context with no @samp{defaultchild} setting.
1437 Implicit context creation can at times give rise to unexpected new
1438 staves or scores. Using @code{\new} to create contexts explicitly
1439 avoids those problems.
1441 @cindex alignAboveContext
1442 @cindex alignBelowContext
1443 @funindex alignAboveContext
1444 @funindex alignBelowContext
1446 Sometimes a context is required to exist for just a brief period, a
1447 good example being the staff context for an ossia. This is usually
1448 achieved by introducing the context definition at the appropriate
1449 place in parallel with corresponding section of the main music.
1450 By default, the temporary context will be placed below all the
1451 existing contexts. To reposition it above the context called
1452 @qq{main}, it should be defined like this:
1455 @code{\new Staff \with @{ alignAboveContext = #"main" @} }
1458 A similar situation arises when positioning a temporary lyrics
1459 context within a multi-staved layout such as a @code{ChoirStaff},
1460 for example, when adding a second verse to a repeated section.
1461 By default the temporary lyrics context will be placed beneath the
1462 lower staves. By defining the temporary lyrics context with
1463 @code{alignBelowContext} it can be positioned correctly beneath
1464 the (named) lyrics context containing the first verse.
1466 Examples showing this repositioning of temporary contexts can be
1467 found elsewhere --- see @rlearning{Annidare le espressioni musicali},
1468 @ref{Modifying single staves} and @ref{Techniques specific to lyrics}.
1471 Manuale di apprendimento:
1472 @rlearning{Annidare le espressioni musicali}.
1474 Guida alla notazione:
1475 @ref{Modifying single staves},
1476 @ref{Techniques specific to lyrics}.
1479 @rprogram{An extra staff appears}.
1482 @file{ly/engraver-init.ly}.
1485 @node Come funziona la Guida al funzionamento interno
1486 @section Come funziona la Guida al funzionamento interno
1487 @translationof Explaining the Internals Reference
1490 * Navigating the program reference::
1491 * Layout interfaces::
1492 * Determining the grob property::
1493 * Naming conventions::
1496 @node Navigating the program reference
1497 @subsection Navigating the program reference
1499 @c TODO remove this (it's in the LM)
1500 @c Replace with more factual directions
1502 Suppose we want to move the fingering indication in the fragment
1505 @lilypond[quote,fragment,verbatim]
1509 If you visit the documentation on fingering instructions (in
1510 @ref{Fingering instructions}), you will notice:
1515 Guida al funzionamento interno: @rinternals{Fingering}.
1520 @c outdated info; probably will delete.
1522 This fragment points to two parts of the program reference: a page
1523 on @code{FingeringEvent} and one on @code{Fingering}.
1525 The page on @code{FingeringEvent} describes the properties of the music
1526 expression for the input @w{@code{-2}}. The page contains many links
1527 forward. For example, it says
1530 Accepted by: @rinternals{Fingering_engraver},
1534 That link brings us to the documentation for the Engraver, the
1538 This engraver creates the following layout objects: @rinternals{Fingering}.
1541 In other words, once the @code{FingeringEvent}s are interpreted, the
1542 @code{Fingering_engraver} plug-in will process them.
1546 @c I can't figure out what this is supposed to mean. -gp
1548 The @code{Fingering_engraver} is also listed to create
1549 @rinternals{Fingering} objects,
1551 @c old info? it doesn't make any sense to me with our current docs.
1553 second bit of information listed under @b{See also} in the Notation
1558 The programmer's reference is available as an HTML document. It is
1559 highly recommended that you read it in HTML form, either online or
1560 by downloading the HTML documentation. This section will be much more
1561 difficult to understand if you are using the
1565 Follow the link to @rinternals{Fingering}. At the top of the
1569 Fingering objects are created by: @rinternals{Fingering_engraver} and
1570 @rinternals{New_fingering_engraver}.
1573 By following related links inside the program reference, we can follow the
1574 flow of information within the program:
1578 @item @rinternals{Fingering}:
1579 @rinternals{Fingering} objects are created by:
1580 @rinternals{Fingering_engraver}
1582 @item @rinternals{Fingering_engraver}:
1583 Music types accepted: @rinternals{fingering-event}
1585 @item @rinternals{fingering-event}:
1586 Music event type @code{fingering-event} is in Music expressions named
1587 @rinternals{FingeringEvent}
1590 This path goes against the flow of information in the program: it
1591 starts from the output, and ends at the input event. You could
1592 also start at an input event, and read with the flow of
1593 information, eventually ending up at the output object(s).
1595 The program reference can also be browsed like a normal document. It
1596 contains chapters on
1598 @rinternals{Music definitions},
1601 @code{Music definitions}
1603 on @rinternals{Translation}, and the @rinternals{Backend}. Every
1604 chapter lists all the definitions used and all properties that may be
1608 @node Layout interfaces
1609 @subsection Layout interfaces
1611 @cindex interface, layout
1612 @cindex layout interface
1615 The HTML page that we found in the previous section describes the
1616 layout object called @rinternals{Fingering}. Such an object is a
1617 symbol within the score. It has properties that store numbers (like
1618 thicknesses and directions), but also pointers to related objects. A
1619 layout object is also called a @emph{Grob}, which is short for Graphical
1620 Object. For more details about Grobs, see @rinternals{grob-interface}.
1622 The page for @code{Fingering} lists the definitions for the
1623 @code{Fingering} object. For example, the page says
1626 @code{padding} (dimension, in staff space):
1632 which means that the number will be kept at a distance of at least 0.5
1636 Each layout object may have several functions as a notational or
1637 typographical element. For example, the Fingering object
1638 has the following aspects
1642 Its size is independent of the horizontal spacing, unlike slurs or beams.
1645 It is a piece of text. Granted, it is usually a very short text.
1648 That piece of text is typeset with a font, unlike slurs or beams.
1651 Horizontally, the center of the symbol should be aligned to the
1652 center of the note head.
1655 Vertically, the symbol is placed next to the note and the staff.
1658 The vertical position is also coordinated with other superscript
1659 and subscript symbols.
1662 Each of these aspects is captured in so-called @emph{interface}s,
1663 which are listed on the @rinternals{Fingering} page at the bottom
1666 This object supports the following interfaces:
1667 @rinternals{item-interface},
1668 @rinternals{self-alignment-interface},
1669 @rinternals{side-position-interface}, @rinternals{text-interface},
1670 @rinternals{text-script-interface}, @rinternals{font-interface},
1671 @rinternals{finger-interface}, and @rinternals{grob-interface}.
1674 Clicking any of the links will take you to the page of the respective
1675 object interface. Each interface has a number of properties. Some of
1676 them are not user-serviceable (@q{Internal properties}), but others
1679 We have been talking of @emph{the} @code{Fingering} object, but actually it
1680 does not amount to much. The initialization file (see
1681 @rlearning{Altre fonti di informazione})
1682 @file{scm/define-grobs.scm} shows the soul of the @q{object},
1687 (avoid-slur . around)
1688 (slur-padding . 0.2)
1689 (staff-padding . 0.5)
1690 (self-alignment-X . 0)
1691 (self-alignment-Y . 0)
1692 (script-priority . 100)
1693 (stencil . ,ly:text-interface::print)
1694 (direction . ,ly:script-interface::calc-direction)
1695 (font-encoding . fetaText)
1696 (font-size . -5) ; don't overlap when next to heads.
1697 (meta . ((class . Item)
1698 (interfaces . (finger-interface
1700 text-script-interface
1702 side-position-interface
1703 self-alignment-interface
1704 item-interface))))))
1708 As you can see, the @code{Fingering} object is nothing more than a
1709 bunch of variable settings, and the webpage in the Guida al funzionamento interno
1710 is directly generated from this definition.
1713 @node Determining the grob property
1714 @subsection Determining the grob property
1716 @c TODO remove this (it's in the LM)
1717 @c Replace with more factual directions
1719 Recall that we wanted to change the position of the @b{2} in
1721 @lilypond[quote,fragment,verbatim]
1725 Since the @b{2} is vertically positioned next to its note, we have to
1726 meddle with the interface associated with this positioning. This is
1727 done using @code{side-position-interface}. The page for this interface
1731 @code{side-position-interface}
1733 Position a victim object (this one) next to other objects (the
1734 support). The property @code{direction} signifies where to put the
1735 victim object relative to the support (left or right, up or down?)
1740 Below this description, the variable @code{padding} is described as
1745 (dimension, in staff space)
1747 Add this much extra space between objects that are next to each other.
1751 By increasing the value of @code{padding}, we can move the
1752 fingering away from the note head. The following command inserts
1753 3 staff spaces of white
1754 between the note and the fingering:
1756 \once \override Voice.Fingering.padding = #3
1759 Inserting this command before the Fingering object is created,
1760 i.e., before @code{c2}, yields the following result:
1762 @lilypond[quote,fragment,verbatim]
1763 \once \override Voice.Fingering.padding = #3
1768 In this case, the context for this tweak is @code{Voice}. This
1769 fact can also be deduced from the program reference, for the page for
1770 the @rinternals{Fingering_engraver} plug-in says
1773 Fingering_engraver is part of contexts: @dots{} @rinternals{Voice}
1777 @node Naming conventions
1778 @subsection Naming conventions
1780 Another thing that is needed, is an overview of the various naming
1784 @item scheme functions: lowercase-with-hyphens (incl. one-word
1786 @item scheme functions: ly:plus-scheme-style
1787 @item music events, music classes and music properties:
1789 @item Grob interfaces: scheme-style
1790 @item backend properties: scheme-style (but X and Y!)
1791 @item contexts (and MusicExpressions and grobs): Capitalized or
1793 @item context properties: lowercaseFollowedByCamelCase
1795 Capitalized_followed_by_lowercase_and_with_underscores
1798 Questions to be answered:
1800 @item Which of these are conventions and which are rules?
1801 @item Which are rules of the underlying language, and which are
1805 @node Modifica delle proprietà
1806 @section Modifica delle proprietà
1807 @translationof Modifying properties
1809 @c TODO change the menu and subsection node names to use
1810 @c backslash once the new macro to handle the refs
1811 @c is available. Need to find and change all refs at
1812 @c the same time. -td
1815 * Overview of modifying properties::
1817 * The override command::
1818 * Il comando tweak::
1819 * set versus override::
1820 * Modifying alists::
1824 @node Overview of modifying properties
1825 @subsection Overview of modifying properties
1827 Each context is responsible for creating certain types of graphical
1828 objects. The settings used for printing these objects are also stored by
1829 context. By changing these settings, the appearance of objects can be
1832 There are two different kinds of properties stored in contexts:
1833 context properties and grob properties. Context properties are
1834 properties that apply to the context as a whole and control
1835 how the context itself is displayed. In contrast, grob properties
1836 apply to specific grob types that will be displayed in the context.
1838 The @code{\set} and @code{\unset} commands are used to change values
1839 for context properties. The @code{\override} and @code{\revert}
1840 commands are used to change values for grob properties.
1843 The syntax for this is
1846 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1849 Here @var{name} is the name of a graphical object, like
1850 @code{Stem} or @code{NoteHead}, and @var{property} is an internal
1851 variable of the formatting system (@q{grob property} or @q{layout
1852 property}). The latter is a symbol, so it must be quoted. The
1853 subsection @ref{Modifying properties}, explains what to fill in
1854 for @var{name}, @var{property}, and @var{value}. Here we only
1855 discuss the functionality of this command.
1860 \override Staff.Stem.thickness = #4.0
1864 makes stems thicker (the default is 1.3, with staff line thickness as a
1865 unit). Since the command specifies @code{Staff} as context, it only
1866 applies to the current staff. Other staves will keep their normal
1867 appearance. Here we see the command in action:
1869 @lilypond[quote,fragment,verbatim]
1871 \override Staff.Stem.thickness = #4.0
1877 The @code{\override} command changes the definition of the @code{Stem}
1878 within the current @code{Staff}. After the command is interpreted
1879 all stems are thickened.
1881 Analogous to @code{\set}, the @var{context} argument may be left out,
1882 causing the default context @code{Voice} to be used. Adding
1883 @code{\once} applies the change during one timestep only.
1885 @lilypond[quote,fragment,verbatim]
1887 \once \override Stem.thickness = #4.0
1892 The @code{\override} must be done before the object is
1893 started. Therefore, when altering @emph{Spanner} objects such as slurs
1894 or beams, the @code{\override} command must be executed at the moment
1895 when the object is created. In this example,
1897 @lilypond[quote,fragment,verbatim]
1898 \override Slur.thickness = #3.0
1900 \override Beam.beam-thickness = #0.6
1905 the slur is fatter but the beam is not. This is because the command for
1906 @code{Beam} comes after the Beam is started, so it has no effect.
1908 Analogous to @code{\unset}, the @code{\revert} command for a context
1909 undoes an @code{\override} command; like with @code{\unset}, it only
1910 affects settings that were made in the same context. In other words, the
1911 @code{\revert} in the next example does not do anything.
1914 \override Voice.Stem.thickness = #4.0
1915 \revert Staff.Stem.thickness
1918 Some tweakable options are called @q{subproperties} and reside inside
1919 properties. To tweak those, use commands of the form
1921 @c leave this as a long long
1923 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1930 \override Stem.details.beamed-lengths = #'(4 4 3)
1936 Guida al funzionamento interno:
1937 @rinternals{Backend},
1938 @rinternals{All layout objects},
1939 @rinternals{OverrideProperty},
1940 @rinternals{RevertProperty},
1941 @rinternals{PropertySet}.
1944 The back-end is not very strict in type-checking object properties.
1945 Cyclic references in Scheme values for properties can cause hangs
1946 or crashes, or both.
1949 @node The set command
1950 @subsection The @code{@bs{}set} command
1954 @cindex changing properties
1956 Each context has a set of @emph{properties}, variables contained
1957 in that context. Context properties are changed with the @code{\set}
1958 command, which has the following syntax:
1961 \set @var{context}.@var{property} = #@var{value}
1964 @var{value} is a Scheme object, which is why it must be preceded by
1965 the @code{#}@tie{}character.
1967 Contexts properties are usually named in
1968 @code{studlyCaps}. They mostly control the translation from
1969 music to notation, e.g. @code{localAlterations} (for determining
1970 whether to print accidentals), or @code{measurePosition} (for
1971 determining when to print a bar line). Context properties can
1972 change value over time while interpreting a piece of music;
1973 @code{measurePosition} is an obvious example of
1974 this. Context properties are modified with @code{\set}.
1976 For example, multimeasure rests will be combined into a single bar
1977 if the context property @code{skipBars} is set to @code{#t}:
1979 @lilypond[quote,fragment,verbatim]
1981 \set Score.skipBars = ##t
1985 If the @var{context} argument is left out, then the property will be
1986 set in the current bottom context (typically @code{ChordNames},
1987 @code{Voice}, @code{TabVoice}, or @code{Lyrics}).
1989 @lilypond[quote,fragment,verbatim]
1990 \set Score.autoBeaming = ##f
1993 \set autoBeaming = ##t
2001 The change is applied @q{on-the-fly}, during the music, so that the
2002 setting only affects the second group of eighth notes.
2004 Note that the bottom-most context does not always contain the property
2005 that you wish to change -- for example, attempting to set the
2006 @code{skipBars} property of the default bottom context, in this case
2007 @code{Voice}, will have no effect, because skipBars is a property of
2008 the @code{Score} context.
2010 @lilypond[quote,fragment,verbatim]
2016 Contexts are hierarchical, so if an enclosing context was specified, for
2017 example @code{Staff}, then the change would also apply to all
2018 @code{Voice}s in the current staff.
2022 The @code{\unset} command:
2025 \unset @var{context}.@var{property}
2029 is used to remove the definition of @var{property} from
2030 @var{context}. This command removes
2031 the definition only if it is set in @var{context}.
2032 Properties that have been set in enclosing contexts will
2033 not be altered by an unset in an enclosed context:
2035 @lilypond[quote,fragment,verbatim]
2036 \set Score.autoBeaming = ##t
2040 \unset Score.autoBeaming
2048 Like @code{\set}, the @var{context} argument does not have to be
2049 specified for a bottom context, so the two statements
2052 \set Voice.autoBeaming = ##t
2053 \set autoBeaming = ##t
2057 are equivalent if the current bottom context is @code{Voice}.
2061 Preceding a @code{\set} or @code{\unset} command by @code{\once}
2062 makes the setting apply to only a single time-step:
2064 @lilypond[quote,fragment,verbatim]
2066 \once \set fontSize = #4.7
2071 A full description of all available context properties is in the
2072 Guida al funzionamento interno, see
2074 @rinternals{Tunable context properties}.
2077 Translation @expansion{} Tunable context properties.
2081 Guida al funzionamento interno:
2082 @rinternals{Tunable context properties}.
2085 @node The override command
2086 @subsection The @code{\override} command
2088 @cindex grob properties
2089 @cindex properties, grob
2092 There is a special type of context property: the grob
2093 description. Grob descriptions are named in @code{StudlyCaps}
2094 (starting with capital letters). They contain the
2095 @q{default settings} for a particular kind of grob as an
2096 association list. See @file{scm/define-grobs.scm}
2097 to see the settings for each grob description. Grob descriptions
2098 are modified with @code{\override}.
2100 The syntax for the @code{\override} command is
2103 \override [@var{context}.]@var{GrobName}.@var{property} = #@var{value}
2106 For example, we can increase the thickness of a note stem by
2107 overriding the @code{thickness} property of the @code{Stem}
2110 @lilypond[quote,fragment,verbatim]
2112 \override Voice.Stem.thickness = #3.0
2116 If no context is specified in an @code{\override}, the bottom
2119 @lilypond[quote,fragment,verbatim]
2120 \override Staff.Stem.thickness = #3.0
2124 \override Stem.thickness = #0.5
2133 Some tweakable options are called @q{subproperties} and reside inside
2134 properties. To tweak those, use commands in the form
2137 \override Stem.details.beamed-lengths = #'(4 4 3)
2140 or to modify the ends of spanners, use a form like these
2143 \override TextSpanner.bound-details.left.text = #"left text"
2144 \override TextSpanner.bound-details.right.text = #"right text"
2148 @cindex reverting overrides
2149 @cindex overrides, reverting
2151 The effects of @code{\override} can be undone by @code{\revert}.
2153 The syntax for the @code{\revert} command is
2156 \revert [@var{context}.]@var{GrobName}.@var{property}
2161 @lilypond[quote,verbatim]
2164 \override Voice.Stem.thickness = #3.0
2166 \revert Voice.Stem.thickness
2171 The effects of @code{\override} and @code{\revert} apply to all
2172 grobs in the affected context from the current time forward:
2174 @lilypond[quote,verbatim]
2178 \override Staff.Stem.thickness = #3.0
2183 \revert Staff.Stem.thickness
2190 @cindex overriding for only one moment
2192 @code{\once} can be used with @code{\override} or @code{\revert}
2193 to affect only the current time step:
2195 @lilypond[quote,verbatim]
2198 \override Stem.thickness = #3.0
2203 \once \override Stem.thickness = #3.0
2211 Commands which change output generally look like
2214 \override Voice.Stem.thickness = #3.0
2218 To construct this tweak we must determine these bits of information:
2221 @item the context: here @code{Voice}.
2222 @item the layout object: here @code{Stem}.
2223 @item the layout property: here @code{thickness}.
2224 @item a sensible value: here @code{3.0}.
2227 @cindex internal documentation
2228 @cindex finding graphical objects
2229 @cindex graphical object descriptions
2232 @cindex internal documentation
2234 For many properties, regardless of the data type of the property, setting the
2235 property to false (@code{#f}) will result in turning it off, causing
2236 LilyPond to ignore that property entirely. This is particularly useful for
2237 turning off grob properties which may otherwise be causing problems.
2239 We demonstrate how to glean this information from the notation manual
2240 and the program reference.
2244 Guida al funzionamento interno:
2245 @rinternals{Backend}
2248 @node Il comando tweak
2249 @subsection Il comando @code{\tweak}
2250 @translationof The tweak command
2255 Changing grob properties
2256 with @code{\override} causes the changes to apply to all of the
2257 given grobs in the context at the moment the change applies.
2258 Sometimes, however, it is desirable to have changes apply to just
2259 one grob, rather than to all grobs in the affected context. This is
2260 accomplished with the @code{\tweak} command, which has the following
2264 \tweak [@var{layout-object}.]@var{grob-property} @var{value}
2267 Specifying @var{layout-object} is optional.
2268 The @code{\tweak} command applies to the music object that immediately
2269 follows @var{value} in the music stream.
2272 In some cases, it is possible to take a short-cut for tuning
2273 graphical objects. For objects that are created directly from
2274 an item in the input file, you can use the @code{\tweak} command.
2277 @lilypond[verbatim,quote]
2283 \tweak duration-log #1
2293 The main use of the @code{\tweak} command is to modify just
2294 one of a number of notation elements which start at the same musical
2295 moment, like the notes of a chord, or tuplet brackets which start
2298 The @code{\tweak} command sets a property in the following object
2299 directly, without requiring the grob name or context to be
2300 specified. For this to work, it is necessary for the @code{\tweak}
2301 command to remain immediately adjacent to the object to which it is
2302 to apply after the input file has been converted to a music stream.
2303 This is often not the case, as many additional elements are inserted
2304 into the music stream implicitly. For example, when a note which is
2305 not part of a chord is processed, LilyPond implicitly inserts a
2306 @code{ChordEvent} event before the note, so separating the tweak
2307 from the note. However, if chord symbols are placed round the
2308 tweak and the note, the @code{\tweak} command comes after the
2309 @code{ChordEvent} in the music stream, so remaining adjacent to the
2310 note, and able to modify it.
2314 @lilypond[verbatim,fragment,quote]
2315 <\tweak color #red c''>4
2321 @lilypond[verbatim,fragment,quote]
2322 \tweak color #red c''4
2327 For an introduction to the syntax and uses of the tweak command
2328 see @rlearning{Metodi di modifica}.
2330 When several similar items are placed at the same musical moment,
2331 the @code{\override} command cannot be used to modify just one of
2332 them -- this is where the @code{\tweak} command must be used.
2333 Items which may appear more than once at the same musical moment
2334 include the following:
2336 @c TODO expand to include any further uses of \tweak
2338 @item note heads of notes inside a chord
2339 @item articulation signs on a single note
2340 @item ties between notes in a chord
2341 @item tuplet brackets starting at the same time
2344 @c TODO add examples of these
2346 @cindex chord, modifying one note in
2348 In this example, the color of one note head and the type of another
2349 note head are modified within a single chord:
2351 @lilypond[verbatim,fragment,quote]
2356 \tweak duration-log #1
2361 @code{\tweak} can be used to modify slurs:
2363 @lilypond[verbatim,quote]
2364 \relative { c'-\tweak thickness #5 ( d e f) }
2368 For the @code{\tweak} command to work, it must
2369 remain immediately adjacent to the object to which it is
2370 to apply after the input file has been converted to a music stream.
2371 Tweaking a whole chord does not do anything since its music event
2372 only acts as a container, and all layout objects are created from events
2373 inside of the @code{EventChord}:
2375 @lilypond[verbatim,fragment,quote]
2376 \tweak color #red c''4
2377 \tweak color #red <c'' e''>4
2378 <\tweak color #red c'' e''>4
2381 The simple @code{\tweak} command cannot be used to modify any object
2382 that is not directly created from the input. In particular
2383 it will not affect stems, automatic
2384 beams or accidentals, since these are generated later by
2385 @code{NoteHead} layout objects rather than by music elements in the
2388 Such indirectly created layout objects can be tweaked using the form
2389 of the @code{\tweak} command in which the grob name is specified
2392 @lilypond[fragment,verbatim,quote]
2393 \tweak Stem.color #red
2394 \tweak Beam.color #green c''8 e''
2395 <c'' e'' \tweak Accidental.font-size #-3 ges''>4
2398 @code{\tweak} cannot be used to modify clefs or time
2399 signatures, since these become separated from any preceding
2400 @code{\tweak} command in the input stream by the automatic
2401 insertion of extra elements required to specify the context.
2403 Several @code{\tweak} commands may be placed before a
2404 notational element -- all affect it:
2406 @lilypond[verbatim,fragment,quote]
2408 -\tweak style #'dashed-line
2409 -\tweak dash-fraction #0.2
2410 -\tweak thickness #3
2416 The music stream which is generated from a section of an input file,
2417 including any automatically inserted elements, may be examined,
2418 see @rextend{Displaying music expressions}. This may be helpful in
2419 determining what may be modified by a @code{\tweak} command, or
2420 in determining how to adjust the input to make a @code{\tweak}
2424 Manuale di apprendimento:
2425 @rlearning{Metodi di modifica}.
2428 @rextend{Displaying music expressions}.
2432 @cindex tweaking control points
2433 @cindex control points, tweaking
2435 The @code{\tweak} command cannot be used to modify the control
2436 points of just one of several ties in a chord, other than the first
2437 one encountered in the input file.
2439 @node set versus override
2440 @subsection @code{\set} vs. @code{\override}
2442 @c TODO Should't a bunch of that be explained earlier?
2446 Both @code{\set} and @code{\override} manipulate properties
2447 associated with contexts. In either case, properties heed the
2448 hierarchy of contexts: properties not set in a context itself show
2449 the values of the respective parent context.
2451 Values and lifetime of context properties are dynamic and only
2452 available when music is being interpreted, @q{iterated}. At the
2453 time of context creation, properties are initialized from the
2454 corresponding context definition and possible context
2455 modifications. Afterwards, changes are achieved with
2456 property-setting commands in the music itself.
2458 Now grob definitions are a special category of context properties.
2459 Since their structure, bookkeeping and use is different from
2460 ordinary context properties, they are accessed with a different
2461 set of commands, and treated separately in the documentation.
2463 As opposed to plain context properties, grob definitions are
2464 subdivided into grob properties. A @qq{grob} (graphical object)
2465 is usually created by an engraver at the time of interpreting a
2466 music expression and receives its initial properties from the
2467 current grob definition of the engraver's context. The engraver
2468 (or other @q{backend} parts of LilyPond) may subsequently add or
2469 change properties to the grob, but that does not affect the
2470 context's grob definition.
2472 What we call @q{grob properties} in the context of user-level
2473 tweaking are actually the properties of a context's grob
2474 definition. In contrast to ordinary context properties, grob
2475 definitions have the bookkeeping required to keep track of its
2476 parts, the individual grob properties (and even subproperties of
2477 them) separately so that it is possible to define those parts in
2478 different contexts and have the overall grob definition at the
2479 time of grob creation be assembled from pieces provided in
2480 different contexts among the current context and its parents.
2482 Grob definitions are manipulated using @code{\override} and
2483 @code{\revert} and have a name starting with a capital letter
2484 (like @samp{NoteHead}) whereas ordinary context properties are
2485 manipulated using @code{\set} and @code{\unset} and are named
2486 starting with a lowercase letter.
2488 @cindex tweak, relation to @code{\override}
2490 @funindex \overrideProperty
2491 The special commands @code{\tweak} and @code{\overrideProperty}
2492 change grob properties bypassing context properties completely.
2493 Instead they catch grobs as they are being created and then
2494 directly set properties on them when they originate from a tweaked
2495 music event or are of a particular kind, respectively.
2497 @node Modifying alists
2498 @subsection Modifying alists
2500 Some user-configurable properties are internally represented as
2501 @emph{alists} (association lists), which store pairs of
2502 @emph{keys} and @emph{values}. The structure of an alist is:
2505 '((@var{key1} . @var{value1})
2506 (@var{key2} . @var{value2})
2507 (@var{key3} . @var{value3})
2511 If an alist is a grob property or @code{\paper} variable, its keys
2512 can be modified individually without affecting other keys.
2514 For example, to reduce the space between adjacent staves in a
2515 staff-group, use the @code{staff-staff-spacing} property of the
2516 @code{StaffGrouper} grob. The property is an alist with four
2517 keys: @code{basic-distance}, @code{minimum-distance},
2518 @code{padding}, and @code{stretchability}. The standard settings
2519 for this property are listed in the @qq{Backend} section of the
2520 Guida al funzionamento interno (see @rinternals{StaffGrouper}):
2523 '((basic-distance . 9)
2524 (minimum-distance . 7)
2526 (stretchability . 5))
2529 One way to bring the staves closer together is by reducing the
2530 value of the @code{basic-distance} key (@code{9}) to match the
2531 value of @code{minimum-distance} (@code{7}). To modify a single
2532 key individually, use a @emph{nested declaration}:
2534 @lilypond[quote,verbatim]
2535 % default space between staves
2537 \new Staff { \clef treble c''1 }
2538 \new Staff { \clef bass c1 }
2541 % reduced space between staves
2542 \new PianoStaff \with {
2543 % this is the nested declaration
2544 \override StaffGrouper.staff-staff-spacing.basic-distance = #7
2546 \new Staff { \clef treble c''1 }
2547 \new Staff { \clef bass c1 }
2551 Using a nested declaration will update the specified key (such as
2552 @code{basic-distance} in the above example) without altering any
2553 other keys already set for the same property.
2555 Now suppose we want the staves to be as close as possible without
2556 overlapping. The simplest way to do this is to set all four alist
2557 keys to zero. However, it is not necessary to enter four nested
2558 declarations, one for each key. Instead, the property can be
2559 completely re-defined with one declaration, as an alist:
2561 @lilypond[quote,verbatim]
2562 \new PianoStaff \with {
2563 \override StaffGrouper.staff-staff-spacing =
2564 #'((basic-distance . 0)
2565 (minimum-distance . 0)
2567 (stretchability . 0))
2569 \new Staff { \clef treble c''1 }
2570 \new Staff { \clef bass c1 }
2574 Note that any keys not explicitly listed in the alist definition
2575 will be reset to their @emph{default-when-unset} values. In the
2576 case of @code{staff-staff-spacing}, any unset key-values would be
2577 reset to zero (except @code{stretchability}, which takes the value
2578 of @code{basic-distance} when unset). Thus the following two
2579 declarations are equivalent:
2582 \override StaffGrouper.staff-staff-spacing =
2583 #'((basic-distance . 7))
2585 \override StaffGrouper.staff-staff-spacing =
2586 #'((basic-distance . 7)
2587 (minimum-distance . 0)
2589 (stretchability . 7))
2592 One (possibly unintended) consequence of this is the removal of
2593 any standard settings that are set in an initialization file and
2594 loaded each time an input file is compiled. In the above example,
2595 the standard settings for @code{padding} and
2596 @code{minimum-distance} (defined in @file{scm/define-grobs.scm})
2597 are reset to their default-when-unset values (zero for both keys).
2598 Defining a property or variable as an alist (of any size) will
2599 always reset all unset key-values to their default-when-unset
2600 values. Unless this is the intended result, it is safer to update
2601 key-values individually with a nested declaration.
2603 @warning{Nested declarations will not work for context property
2604 alists (such as @code{beamExceptions}, @code{keyAlterations},
2605 @code{timeSignatureSettings}, etc.). These properties can only be
2606 modified by completely re-defining them as alists.}
2609 @node Proprietà e concetti utili
2610 @section Proprietà e concetti utili
2611 @translationof Useful concepts and properties
2616 * Direction and placement::
2617 * Distances and measurements::
2619 * Staff symbol properties::
2621 * Visibility of objects::
2623 * Rotating objects::
2627 @subsection Input modes
2629 The way in which the notation contained within an input file is
2630 interpreted is determined by the current input mode.
2632 @subsubsubheading Chord mode
2634 This is activated with the @code{\chordmode} command, and causes
2635 input to be interpreted with the syntax of chord notation, see
2636 @ref{Chord notation}. Chords are rendered as notes on a staff.
2638 Chord mode is also activated with the @code{\chords} command.
2639 This also creates a new @code{ChordNames} context and
2640 causes the following input to be interpreted with the syntax of
2641 chord notation and rendered as chord names in the @code{ChordNames}
2642 context, see @ref{Printing chord names}.
2644 @subsubsubheading Drum mode
2646 This is activated with the @code{\drummode} command, and causes
2647 input to be interpreted with the syntax of drum notation, see
2648 @ref{Basic percussion notation}.
2650 Drum mode is also activated with the @code{\drums} command.
2651 This also creates a new @code{DrumStaff} context and causes the
2652 following input to be interpreted with the syntax of drum notation
2653 and rendered as drum symbols on a drum staff, see
2654 @ref{Basic percussion notation}.
2656 @subsubsubheading Figure mode
2658 This is activated with the @code{\figuremode} command, and causes
2659 input to be interpreted with the syntax of figured bass, see
2660 @ref{Entering figured bass}.
2662 Figure mode is also activated with the @code{\figures} command.
2663 This also creates a new @code{FiguredBass} context and causes the
2664 following input to be interpreted with the figured bass syntax
2665 and rendered as figured bass symbols in the @code{FiguredBass}
2666 context, see @ref{Introduction to figured bass}.
2668 @subsubsubheading Fret and tab modes
2670 There are no special input modes for entering fret and tab symbols.
2672 To create tab diagrams, enter notes or chords in note mode and
2673 render them in a @code{TabStaff} context, see
2674 @ref{Default tablatures}.
2676 To create fret diagrams above a staff, you have two choices.
2677 You can either use the @code{FretBoards} context (see
2678 @ref{Automatic fret diagrams} or you can enter them as a markup
2679 above the notes using the @code{\fret-diagram} command (see
2680 @ref{Fret diagram markups}).
2682 @subsubsubheading Lyrics mode
2684 This is activated with the @code{\lyricmode} command, and causes
2685 input to be interpreted as lyric syllables with optional durations
2686 and associated lyric modifiers, see @ref{Vocal music}.
2688 Lyric mode is also activated with the @code{\addlyrics} command.
2689 This also creates a new @code{Lyrics} context and an implicit
2690 @code{\lyricsto} command which associates the following lyrics
2691 with the preceding music.
2693 @subsubsubheading Markup mode
2695 This is activated with the @code{\markup} command, and causes
2696 input to be interpreted with the syntax of markup, see
2697 @ref{Text markup commands}.
2699 @subsubsubheading Note mode
2701 This is the default mode or it may be activated with the
2702 @code{\notemode} command. Input is interpreted as pitches,
2703 durations, markup, etc and typeset as musical notation on a staff.
2705 It is not normally necessary to specify note mode explicitly, but
2706 it may be useful to do so in certain situations, for example if you
2707 are in lyric mode, chord mode or any other mode and want to insert
2708 something that only can be done with note mode syntax.
2711 @node Direction and placement
2712 @subsection Direction and placement
2714 In typesetting music the direction and placement of many items is
2715 a matter of choice. For example, the stems of notes can
2716 be directed up or down; lyrics, dynamics, and other expressive
2717 marks may be placed above or below the staff; text may be aligned
2718 left, right or center; etc. Most of these choices may be left to
2719 be determined automatically by LilyPond, but in some cases it may
2720 be desirable to force a particular direction or placement.
2723 * Articulation direction indicators::
2724 * The direction property::
2727 @node Articulation direction indicators
2728 @unnumberedsubsubsec Articulation direction indicators
2730 By default some directions are always up or always down (e.g.
2731 dynamics or fermata), while other things can alternate between
2732 up or down based on the stem direction (like slurs or accents).
2734 @c TODO Add table showing these
2736 The default action may be overridden by prefixing the articulation
2737 by a @emph{direction indicator}. Three direction indicators are
2738 available: @code{^} (meaning @qq{up}), @code{_} (meaning @qq{down})
2739 and @code{-} (meaning @qq{use default direction}). The direction
2740 indicator can usually be omitted, in which case @code{-} is assumed,
2741 but a direction indicator is @strong{always} required before
2744 @item @code{\tweak} commands
2745 @item @code{\markup} commands
2746 @item @code{\tag} commands
2747 @item string markups, e.g. -"string"
2748 @item fingering instructions, e.g. @w{@code{-1}}
2749 @item articulation shortcuts, e.g. @w{@code{-.}}, @w{@code{->}}, @w{@code{--}}
2752 Direction indicators affect only the next note:
2754 @lilypond[verbatim,quote]
2763 @node The direction property
2764 @unnumberedsubsubsec The direction property
2766 The position or direction of many layout objects is controlled by the
2767 @code{direction} property.
2769 The value of the @code{direction} property may be set to @code{1},
2770 meaning @qq{up} or @qq{above}, or to @w{@code{-1}}, meaning @qq{down} or
2771 @qq{below}. The symbols @code{UP} and @code{DOWN} may be used instead
2772 of @code{1} and @w{@code{-1}} respectively. The default direction may
2773 be specified by setting @code{direction} to @code{0} or @code{CENTER}.
2774 Alternatively, in many cases predefined commands exist to specify the
2775 direction. These are of the form
2778 @code{\xxxUp}, @code{\xxxDown} or @code{\xxxNeutral}
2782 where @code{\xxxNeutral} means @qq{use the default} direction.
2783 See @rlearning{Oggetti interni al rigo}.
2785 In a few cases, arpeggio for example, the value of the @code{direction}
2786 property can specify whether the object is to be placed to the right or
2787 left of the parent. In this case @w{@code{-1}} or @code{LEFT} means
2788 @qq{to the left} and @code{1} or @code{RIGHT} means @qq{to the right}.
2789 @code{0} or @code{CENTER} means @qq{use the default} direction.
2792 These all have side-axis set to #X
2793 AmbitusAccidental - direction has no effect
2795 StanzaNumber - not tried
2796 TrillPitchAccidental - not tried
2797 TrillPitchGroup - not tried
2800 These indications affect all notes until they are canceled.
2802 @lilypond[verbatim,quote]
2813 In polyphonic music, it is generally better to specify an explicit
2814 @code{voice} than change an object's direction. For more information.
2815 See @ref{Multiple voices}.
2818 Manuale di apprendimento:
2819 @rlearning{Oggetti interni al rigo}.
2821 Guida alla notazione:
2822 @ref{Multiple voices}.
2825 @node Distances and measurements
2826 @subsection Distances and measurements
2828 @cindex distances, absolute
2829 @cindex distances, scaled
2836 Distances in LilyPond are of two types: absolute and scaled.
2838 Absolute distances are used for specifying margins, indents, and
2839 other page layout details, and are by default specified in
2840 millimeters. Distances may be specified in other units by
2841 following the quantity by @code{\mm}, @code{\cm},
2842 @code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27 of
2843 an inch). Page layout distances can also be specified in scalable
2844 units (see the following paragraph) by appending
2845 @code{\staff-space} to the quantity. Page layout is described in
2846 detail in @ref{Page layout}.
2848 Scaled distances are always specified in units of the staff-space
2849 or, rarely, the half staff-space. The staff-space is the distance
2850 between two adjacent staff lines. The default value can be changed
2851 globally by setting the global staff size, or it can be overridden
2852 locally by changing the @code{staff-space} property of
2853 @code{StaffSymbol}. Scaled distances automatically scale with any
2854 change to the either the global staff size or the
2855 @code{staff-space} property of @code{StaffSymbol}, but fonts scale
2856 automatically only with changes to the global staff size.
2857 The global staff size thus enables the overall size of a rendered
2858 score to be easily varied. For the methods of setting the global
2859 staff size see @ref{Setting the staff size}.
2863 If just a section of a score needs to be rendered to a different
2864 scale, for example an ossia section or a footnote, the global staff
2865 size cannot simply be changed as this would affect the entire score.
2866 In such cases the change in size is made by overriding both the
2867 @code{staff-space} property of @code{StaffSymbol} and the size of
2868 the fonts. A Scheme function, @code{magstep}, is available to
2869 convert from a font size change to the equivalent change in
2870 @code{staff-space}. For an explanation and an example of its use,
2871 see @rlearning{Lunghezza e spessore degli oggetti}.
2874 Manuale di apprendimento:
2875 @rlearning{Lunghezza e spessore degli oggetti}.
2877 Guida alla notazione:
2879 @ref{Setting the staff size}.
2883 @subsection Dimensions
2886 @cindex bounding box
2888 The dimensions of a graphical object specify the positions of the left
2889 and right edges and the bottom and top edges of the objects' bounding
2890 box as distances from the objects' reference point in units of
2891 staff-spaces. These positions are usually coded as two Scheme pairs.
2892 For example, the text markup command @code{\with-dimensions} takes
2893 three arguments, the first two of which are a Scheme pair giving the
2894 left and right edge positions and a Scheme pair giving the bottom and
2898 \with-dimensions #'(-5 . 10) #'(-3 . 15) @var{arg}
2901 This specifies a bounding box for @var{arg} with its left edge at -5,
2902 its right edge at 10, its bottom edge at -3 and its top edge at 15,
2903 all measured from the objects' reference point in units of
2907 Guida alla notazione:
2908 @ref{Distances and measurements}.
2911 @node Staff symbol properties
2912 @subsection Staff symbol properties
2914 @cindex adjusting staff symbol
2915 @cindex drawing staff symbol
2916 @cindex staff symbol, setting of
2918 @c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
2919 @c Need to think of uses for these properties. Eg 'line-positions
2920 @c is used in a snippet to thicken centre line.
2921 @c If retained, add @ref to here in 1.6.2 -td
2923 The vertical position of staff lines and the number of staff lines
2924 can be defined at the same time. As the following example shows,
2925 note positions are not influenced by the staff line positions.
2927 @warning{The @code{'line-positions} property overrides the
2928 @code{'line-count} property. The number of staff lines is
2929 implicitly defined by the number of elements in the list of values
2930 for @code{'line-positions}.}
2932 @lilypond[verbatim,quote]
2934 \override StaffSymbol.line-positions = #'(7 3 0 -4 -6 -7)
2936 \relative { a4 e' f b | d1 }
2939 The width of a staff can be modified. The units are staff
2940 spaces. The spacing of objects inside the staff is not affected by
2943 @lilypond[verbatim,quote]
2945 \override StaffSymbol.width = #23
2947 \relative { a4 e' f b | d1 }
2952 @subsection Spanners
2954 Many objects of musical notation extend over several notes or even
2955 several bars. Examples are slurs, beams, tuplet brackets, volta
2956 repeat brackets, crescendi, trills, and glissandi. Such objects
2957 are collectively called @qq{spanners}, and have special properties to control
2958 their appearance and behaviour. Some of these properties are common
2959 to all spanners; others are restricted to a sub-set of the spanners.
2961 All spanners support the @code{spanner-interface}. A few, essentially
2962 those that draw a straight line between the two objects, support in
2963 addition the @code{line-spanner-interface}.
2966 * Using the spanner-interface::
2967 * Using the line-spanner-interface::
2970 @node Using the spanner-interface
2971 @unnumberedsubsubsec Using the @code{spanner-interface}
2973 This interface provides two properties that apply to several spanners.
2975 @subsubsubheading The @code{minimum-length} property
2977 The minimum length of the spanner is specified by the
2978 @code{minimum-length} property. Increasing this usually has the
2979 necessary effect of increasing the spacing of the notes between the
2980 two end points. However, this override has no effect on
2981 many spanners, as their length is determined by other considerations.
2982 A few examples where it is effective are shown below.
2992 Works as long as callback is made:
2996 Works not at all for:
3005 @lilypond[verbatim,quote,fragment]
3008 % increase the length of the tie
3009 -\tweak minimum-length #5
3013 @lilypond[verbatim,quote]
3014 \relative \compressMMRests {
3017 % increase the length of the rest bar
3018 \once \override MultiMeasureRest.minimum-length = #20
3024 @lilypond[verbatim,quote]
3027 % increase the length of the hairpin
3028 \override Hairpin.minimum-length = #20
3033 This override can also be used to increase the length of slurs and
3036 @lilypond[verbatim,quote]
3040 -\tweak minimum-length #5
3045 -\tweak minimum-length #5
3050 For some layout objects, the @code{minimum-length} property becomes
3051 effective only if the @code{set-spacing-rods} procedure is called
3052 explicitly. To do this, the @code{springs-and-rods} property should
3053 be set to @code{ly:spanner::set-spacing-rods}. For example,
3054 the minimum length of a glissando has no effect unless the
3055 @code{springs-and-rods} property is set:
3057 @lilypond[verbatim,fragment,quote]
3061 % not effective alone
3062 \once \override Glissando.minimum-length = #20
3065 % effective only when both overrides are present
3066 \once \override Glissando.minimum-length = #20
3067 \once \override Glissando.springs-and-rods = #ly:spanner::set-spacing-rods
3071 The same is true of the @code{Beam} object:
3073 @lilypond[verbatim,fragment,quote]
3074 % not effective alone
3075 \once \override Beam.minimum-length = #20
3078 % effective only when both overrides are present
3079 \once \override Beam.minimum-length = #20
3080 \once \override Beam.springs-and-rods = #ly:spanner::set-spacing-rods
3084 @subsubsubheading The @code{to-barline} property
3086 The second useful property of the @code{spanner-interface} is
3087 @code{to-barline}. By default this is true, causing hairpins and
3088 other spanners which are terminated on the first note of a measure to
3089 end instead on the immediately preceding bar line. If set to false,
3090 the spanner will extend beyond the bar line and end on the note
3093 @lilypond[verbatim,quote]
3095 a' \< a a a a \! a a a \break
3096 \override Hairpin.to-barline = ##f
3097 a \< a a a a \! a a a
3101 This property is not effective for all spanners. For example,
3102 setting it to @code{#t} has no effect on slurs or phrasing slurs
3103 or on other spanners for which terminating on the bar line would
3106 @node Using the line-spanner-interface
3107 @unnumberedsubsubsec Using the @code{line-spanner-interface}
3109 Objects which support the @code{line-spanner-interface} include
3112 @item @code{DynamicTextSpanner}
3113 @item @code{Glissando}
3114 @item @code{TextSpanner}
3115 @item @code{TrillSpanner}
3116 @item @code{VoiceFollower}
3119 The routine responsible for drawing the stencils for these spanners is
3120 @code{ly:line-spanner::print}. This routine determines the
3121 exact location of the two end points and draws a line
3122 between them, in the style requested. The locations of the two
3123 end points of the spanner are computed on-the-fly, but it is
3124 possible to override their Y-coordinates. The
3125 properties which need to be specified are nested
3126 two levels down within the property hierarchy, but the syntax of
3127 the @code{\override} command is quite simple:
3129 @lilypond[quote,fragment,verbatim]
3131 \once \override Glissando.bound-details.left.Y = #3
3132 \once \override Glissando.bound-details.right.Y = #-2
3136 The units for the @code{Y} property are @code{staff-space}s,
3137 with the center line of the staff being the zero point.
3138 For the glissando, this is the value for @code{Y} at the
3139 X-coordinate corresponding to the center point of each note head,
3140 if the line is imagined to be extended to there.
3142 If @code{Y} is not set, the value is computed from the vertical
3143 position of the corresponding attachment point of the spanner.
3145 In case of a line break, the values for the end points are
3146 specified by the @code{left-broken} and @code{right-broken}
3147 sub-lists of @code{bound-details}. For example:
3149 @lilypond[ragged-right,fragment,verbatim,quote]
3150 \override Glissando.breakable = ##t
3151 \override Glissando.bound-details.right-broken.Y = #-3
3152 c''1 \glissando \break
3157 A number of further properties of the @code{left} and
3158 @code{right} sub-lists of the @code{bound-details} property
3159 may be modified in the same way as @code{Y}:
3163 This sets the Y-coordinate of the end point, in @code{staff-space}s
3164 offset from the staff center line. By default, it is the center of
3165 the bound object, so a glissando points to the vertical center of
3168 For horizontal spanners, such as text spanners and trill spanners,
3169 it is hardcoded to 0.
3172 This determines where the line starts and ends in the X-direction,
3173 relative to the bound object. So, a value of @w{@code{-1}} (or
3174 @code{LEFT}) makes the line start/end at the left side of the note
3175 head it is attached to.
3178 This is the absolute X-coordinate of the end point. It is usually
3179 computed on the fly, and overriding it has little useful effect.
3182 Line spanners may have symbols at the beginning or end, which is
3183 contained in this sub-property. This is for internal use; it is
3184 recommended that @code{text} be used instead.
3187 This is a markup that is evaluated to yield the stencil. It is used
3188 to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
3190 @lilypond[quote,ragged-right,fragment,verbatim]
3191 \override TextSpanner.bound-details.left.text
3192 = \markup { \small \bold Slower }
3193 \relative { c''2\startTextSpan b c a\stopTextSpan }
3196 @item stencil-align-dir-y
3197 @item stencil-offset
3198 Without setting one of these, the stencil is simply put at the
3199 end-point, centered on the line, as defined by the @code{X} and
3200 @code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
3201 or @code{stencil-offset} will move the symbol at the edge vertically
3202 relative to the end point of the line:
3204 @lilypond[quote,fragment,verbatim]
3205 \override TextSpanner.bound-details.left.stencil-align-dir-y = #-2
3206 \override TextSpanner.bound-details.right.stencil-align-dir-y = #UP
3208 \override TextSpanner.bound-details.left.text = #"ggg"
3209 \override TextSpanner.bound-details.right.text = #"hhh"
3211 \relative { c'4^\startTextSpan c c c \stopTextSpan }
3214 Note that negative values move the text @emph{up}, contrary to the
3215 effect that might be expected, as a value of @w{@code{-1}} or
3216 @code{DOWN} means align the @emph{bottom} edge of the text with
3217 the spanner line. A value of @code{1} or @code{UP} aligns
3218 the top edge of the text with the spanner line.
3221 Setting this sub-property to @code{#t} produces an arrowhead at the
3225 This sub-property controls the space between the specified
3226 end point of the line and the actual end. Without padding, a
3227 glissando would start and end in the center of each note head.
3231 The music function @code{\endSpanners} terminates the spanner
3232 which starts on the immediately following note prematurely. It
3233 is terminated after exactly one note, or at the following bar line
3234 if @code{to-barline} is true and a bar line occurs before the next
3237 @lilypond[verbatim,quote,ragged-right]
3240 c2 \startTextSpan c2 c2
3246 When using @code{\endSpanners} it is not necessary to close
3247 \startTextSpan with \stopTextSpan, nor is it necessary to close
3248 hairpins with @code{\!}.
3251 Guida al funzionamento interno:
3252 @rinternals{TextSpanner},
3253 @rinternals{Glissando},
3254 @rinternals{VoiceFollower},
3255 @rinternals{TrillSpanner},
3256 @rinternals{line-spanner-interface}.
3259 @node Visibility of objects
3260 @subsection Visibility of objects
3262 @cindex objects, visibility of
3263 @cindex grobs, visibility of
3264 @cindex visibility of objects
3266 There are four main ways in which the visibility of layout objects
3267 can be controlled: their stencil can be removed, they can be made
3268 transparent, they can be colored white, or their
3269 @code{break-visibility} property can be overridden. The first
3270 three apply to all layout objects; the last to just a few -- the
3271 @emph{breakable} objects. The Manuale di apprendimento introduces these
3272 four techniques, see @rlearning{Visibilità e colore degli oggetti}.
3274 There are also a few other techniques which are specific to
3275 certain layout objects. These are covered under Special
3279 * Removing the stencil::
3280 * Making objects transparent::
3281 * Painting objects white::
3282 * Using break-visibility::
3283 * Special considerations::
3287 @node Removing the stencil
3288 @unnumberedsubsubsec Removing the stencil
3290 @cindex stencil, removing
3293 Every layout object has a stencil property. By default this is set
3294 to the specific function which draws that object. If this property
3295 is overridden to @code{#f} no function will be called and the object
3296 will not be drawn. The default action can be recovered with
3299 @lilypond[quote,fragment,verbatim]
3301 \override Score.BarLine.stencil = ##f
3303 \revert Score.BarLine.stencil
3307 This rather common operation has a shortcut @code{\omit}:
3309 @lilypond[quote,fragment,verbatim]
3313 \undo \omit Score.BarLine
3317 @node Making objects transparent
3318 @unnumberedsubsubsec Making objects transparent
3320 @cindex transparent, making objects
3323 Every layout object has a transparent property which by default is
3324 set to @code{#f}. If set to @code{#t} the object still occupies
3325 space but is made invisible.
3327 @lilypond[quote,fragment,verbatim]
3329 \once \override NoteHead.transparent = ##t
3333 This rather common operation has a shortcut @code{\hide}:
3335 @lilypond[quote,fragment,verbatim]
3337 \once \hide NoteHead
3341 @node Painting objects white
3342 @unnumberedsubsubsec Painting objects white
3344 @cindex objects, coloring
3345 @cindex coloring objects
3347 @cindex printing order
3348 @cindex overwriting objects
3349 @cindex objects, overwriting
3350 @cindex grobs, overwriting
3352 Every layout object has a color property which by default is set
3353 to @code{black}. If this is overridden to @code{white} the object
3354 will be indistinguishable from the white background. However,
3355 if the object crosses other objects the color of the crossing
3356 points will be determined by the order in which they are drawn,
3357 and this may leave a ghostly image of the white object, as shown
3360 @lilypond[quote,fragment,verbatim]
3361 \override Staff.Clef.color = #white
3365 This may be avoided by changing the order of printing the objects.
3366 All layout objects have a @code{layer} property which should be set
3367 to an integer. Objects with the lowest value of @code{layer} are
3368 drawn first, then objects with progressively higher values are drawn,
3369 so objects with higher values overwrite objects with lower values.
3370 By default most objects are assigned a @code{layer} value of
3371 @code{1}, although a few objects, including @code{StaffSymbol} and
3372 @code{BarLine}, are assigned a value of @code{0}. The order of
3373 printing objects with the same value of @code{layer} is indeterminate.
3375 In the example above the white clef, with a default @code{layer}
3376 value of @code{1}, is drawn after the staff lines (default
3377 @code{layer} value @code{0}), so overwriting them. To change this,
3378 the @code{Clef} object must be given in a lower value of
3379 @code{layer}, say @w{@code{-1}}, so that it is drawn earlier:
3381 @lilypond[quote,fragment,verbatim]
3382 \override Staff.Clef.color = #white
3383 \override Staff.Clef.layer = #-1
3387 @node Using break-visibility
3388 @unnumberedsubsubsec Using break-visibility
3390 @c TODO Add making other objects breakable
3392 @cindex break-visibility
3394 Most layout objects are printed only once, but some like
3395 bar lines, clefs, time signatures and key signatures, may need
3396 to be printed twice when a line break occurs -- once at the end
3397 of the line and again at the start of the next line. Such
3398 objects are called @emph{breakable}, and have a property, the
3399 @code{break-visibility} property to control their visibility
3400 at the three positions in which they may appear -- at the
3401 start of a line, within a line if they are changed, and at the
3402 end of a line if a change takes place there.
3404 For example, the time signature
3405 by default will be printed at the start of the first line, but
3406 nowhere else unless it changes, when it will be printed at the
3407 point at which the change occurs. If this change occurs at the
3408 end of a line the new time signature will be printed at the start
3409 of the next line and a cautionary time signature will be printed
3410 at the end of the previous line as well.
3412 This behaviour is controlled by the @code{break-visibility}
3413 property, which is explained in
3414 @c Leave this ref on a newline - formats incorrectly otherwise -td
3415 @rlearning{Visibilità e colore degli oggetti}. This property takes
3416 a vector of three booleans which, in order, determine whether the
3417 object is printed at the end of, within the body of, or at the
3418 beginning of a line. Or to be more precise, before a line break,
3419 where there is no line break, or after a line break.
3421 Alternatively, these eight combinations may be specified
3422 by pre-defined functions, defined in @file{scm/output-lib.scm},
3423 where the last three columns indicate whether the layout objects
3424 will be visible in the positions shown at the head of the columns:
3426 @multitable {@code{begin-of-line-invisible}} {@code{#(#t #t #t)}} {Before} {At no} {After}
3427 @headitem Function @tab Vector @tab Before @tab At no @tab After
3428 @headitem form @tab form @tab break @tab break @tab break
3430 @item @code{all-visible} @tab @code{#(#t #t #t)} @tab yes @tab yes @tab yes
3431 @item @code{begin-of-line-visible} @tab @code{#(#f #f #t)} @tab no @tab no @tab yes
3432 @item @code{center-visible} @tab @code{#(#f #t #f)} @tab no @tab yes @tab no
3433 @item @code{end-of-line-visible} @tab @code{#(#t #f #f)} @tab yes @tab no @tab no
3434 @item @code{begin-of-line-invisible} @tab @code{#(#t #t #f)} @tab yes @tab yes @tab no
3435 @item @code{center-invisible} @tab @code{#(#t #f #t)} @tab yes @tab no @tab yes
3436 @item @code{end-of-line-invisible} @tab @code{#(#f #t #t)} @tab no @tab yes @tab yes
3437 @item @code{all-invisible} @tab @code{#(#f #f #f)} @tab no @tab no @tab no
3440 The default settings of @code{break-visibility} depend on the
3441 layout object. The following table shows all the layout objects
3442 of interest which are affected by @code{break-visibility} and the
3443 default setting of this property:
3445 @multitable @columnfractions .3 .3 .4
3447 @headitem Layout object @tab Usual context @tab Default setting
3449 @c omit Ambitus as it appears not to be affected by break-visibility -td
3450 @c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
3451 @item @code{BarLine} @tab @code{Score} @tab calculated
3452 @item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
3453 @c omit the following item until it can be explained -td
3454 @c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
3455 @item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3456 @item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
3457 @item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
3458 @item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
3459 @item @code{KeyCancellation} @tab @code{Staff} @tab @code{begin-of-line-invisible}
3460 @item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
3461 @c omit LeftEdge until it can be explained -td
3462 @c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
3463 @item @code{ClefModifier} @tab @code{Staff} @tab @code{begin-of-line-visible}
3464 @item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
3465 @item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
3469 The example below shows the use of the vector form to control the
3470 visibility of bar lines:
3472 @lilypond[quote,verbatim,ragged-right]
3476 % Remove bar line at the end of the current line
3477 \once \override Score.BarLine.break-visibility = ##(#f #t #t)
3484 Although all three components of the vector used to override
3485 @code{break-visibility} must be present, not all of them are
3486 effective with every layout object, and some combinations may
3487 even give errors. The following limitations apply:
3490 @item Bar lines cannot be printed at start of line.
3491 @item A bar number cannot be printed at the start of the first
3492 line unless it is set to be different from 1.
3493 @item Clef -- see below
3494 @item Double percent repeats are either all printed or all
3495 suppressed. Use begin-of line-invisible to print and
3496 all-invisible to suppress.
3497 @item Key signature -- see below
3498 @item ClefModifier -- see below
3501 @node Special considerations
3502 @unnumberedsubsubsec Special considerations
3504 @subsubsubheading Visibility following explicit changes
3506 @cindex key signature, visibility following explicit change
3507 @cindex explicitKeySignatureVisibility
3508 @cindex clef, visibility following explicit change
3509 @cindex explicitClefVisibility
3511 The @code{break-visibility} property controls the visibility of
3512 key signatures and changes of clef only at the start of lines,
3513 i.e. after a break. It has no effect on the visibility of the
3514 key signature or clef following an explicit key change or an
3515 explicit clef change within or at the end of a line. In the
3516 following example the key signature following the explicit change
3517 to B-flat major is still visible, even though @code{all-invisible}
3520 @lilypond[quote,verbatim,ragged-right]
3524 % Try to remove all key signatures
3525 \override Staff.KeySignature.break-visibility = #all-invisible
3534 The visibility of such explicit key signature and clef changes is
3535 controlled by the @code{explicitKeySignatureVisibility} and
3536 @code{explicitClefVisibility} properties. These are the equivalent
3537 of the @code{break-visibility} property and both take a vector of
3538 three booleans or the predefined functions listed above, exactly like
3539 @code{break-visibility}. Both are properties of the Staff context,
3540 not the layout objects themselves, and so they are set using the
3541 @code{\set} command. Both are set by default to @code{all-visible}.
3542 These properties control only the visibility of key signatures and
3543 clefs resulting from explicit changes and do not affect key
3544 signatures and clefs at the beginning of lines;
3545 @code{break-visibility} must still be overridden in the appropriate
3546 object to remove these.
3548 @lilypond[quote,verbatim,ragged-right]
3552 \set Staff.explicitKeySignatureVisibility = #all-invisible
3553 \override Staff.KeySignature.break-visibility = #all-invisible
3561 @subsubsubheading Visibility of cancelling accidentals
3563 To remove the cancelling accidentals printed at an explicit key
3564 change, set the Staff context property @code{printKeyCancellation}
3567 @lilypond[quote,verbatim,ragged-right]
3571 \set Staff.explicitKeySignatureVisibility = #all-invisible
3572 \set Staff.printKeyCancellation = ##f
3573 \override Staff.KeySignature.break-visibility = #all-invisible
3581 With these overrides only the accidentals before the notes remain
3582 to indicate the change of key.
3584 Note that when changing the key to C@tie{}major or A@tie{}minor
3585 the cancelling accidentals would be the @emph{only} indication of
3586 the key change. In this case setting @code{printKeyCancellation} to
3587 @code{#f} has no effect:
3589 @lilypond[quote,verbatim,ragged-right]
3593 \set Staff.explicitKeySignatureVisibility = #all-invisible
3594 \set Staff.printKeyCancellation = ##f
3602 To suppress the cancelling accidentals even when the key is
3603 changed to C@tie{}major or A@tie{}minor, override
3604 the visibility of the @code{KeyCancellation} grob instead:
3606 @lilypond[quote,verbatim,ragged-right]
3610 \set Staff.explicitKeySignatureVisibility = #all-invisible
3611 \override Staff.KeyCancellation.break-visibility = #all-invisible
3619 @c TODO Add visibility of cautionary accidentals before notes
3621 @subsubsubheading Automatic bars
3623 @cindex automaticBars
3624 @cindex bar lines, suppressing
3626 As a special case, the printing of bar lines can also be turned off
3627 by setting the @code{automaticBars} property in the Score context.
3628 If set to @code{#f}, bar lines will not be printed automatically;
3629 they must be explicitly created with a @code{\bar} command. Unlike
3630 the @code{\cadenzaOn} predefined command, measures are still counted.
3631 Bar generation will resume according to that count if this property
3632 is later set to @code{#t}. When set to @code{#f}, line breaks can
3633 occur only at explicit @code{\bar} commands.
3637 @subsubsubheading Transposed clefs
3639 @cindex transposed clefs, visibility of
3640 @cindex visibility of transposed clefs
3641 @cindex clefs, visibility of transposition
3643 The small transposition symbol on transposed clefs is produced by the
3644 @code{ClefModifier} layout object. Its visibility is automatically
3645 inherited from the @code{Clef} object, so it is not necessary to apply
3646 any required @code{break-visibility} overrides to the @code{ClefModifier}
3647 layout objects to suppress transposition symbols for invisible clefs.
3649 For explicit clef changes, the @code{explicitClefVisibility}
3650 property controls both the clef symbol and any transposition symbol
3654 Manuale di apprendimento:
3655 @rlearning{Visibilità e colore degli oggetti}.
3659 @subsection Line styles
3661 Some performance indications, e.g., @i{rallentando} and
3662 @i{accelerando} and @i{trills} are written as text and are
3663 extended over many measures with lines, sometimes dotted or wavy.
3665 These all use the same routines as the glissando for drawing the
3666 texts and the lines, and tuning their behavior is therefore also
3667 done in the same way. It is done with a spanner, and the routine
3668 responsible for drawing the spanners is
3669 @code{ly:line-spanner::print}. This routine determines the
3670 exact location of the two @i{span points} and draws a line
3671 between them, in the style requested.
3673 Here is an example showing the different line styles available,
3674 and how to tune them.
3676 @lilypond[ragged-right,verbatim,quote]
3679 \once \override Glissando.style = #'dashed-line
3681 \override Glissando.style = #'dotted-line
3683 \override Glissando.style = #'zigzag
3685 \override Glissando.style = #'trill
3690 The locations of the end-points of the spanner are computed
3691 on-the-fly for every graphic object, but it is possible to
3695 @lilypond[ragged-right,verbatim,quote]
3698 \once \override Glissando.bound-details.right.Y = #-2
3703 The value for @code{Y} is set to @w{@code{-2}} for the right end
3704 point. The left side may be similarly adjusted by specifying
3705 @code{left} instead of @code{right}.
3707 If @code{Y} is not set, the value is computed from the vertical
3708 position of the left and right attachment points of the spanner.
3710 Other adjustments of spanners are possible, for details, see
3713 @node Rotating objects
3714 @subsection Rotating objects
3716 Both layout objects and elements of markup text can be rotated by
3717 any angle about any point, but the method of doing so differs.
3720 * Rotating layout objects::
3724 @node Rotating layout objects
3725 @unnumberedsubsubsec Rotating layout objects
3727 @cindex rotating objects
3728 @cindex objects, rotating
3730 All layout objects which support the @code{grob-interface} can be
3731 rotated by setting their @code{rotation} property. This takes a
3732 list of three items: the angle of rotation counter-clockwise,
3733 and the x and y coordinates of the point relative to the object's
3734 reference point about which the rotation is to be performed. The
3735 angle of rotation is specified in degrees and the coordinates in
3738 The angle of rotation and the coordinates of the rotation point must
3739 be determined by trial and error.
3741 @cindex hairpins, angled
3742 @cindex angled hairpins
3744 There are only a few situations where the rotation of layout
3745 objects is useful; the following example shows one situation where
3748 @lilypond[quote,fragment,verbatim]
3750 \override Hairpin.rotation = #'(20 -1 0)
3754 @node Rotating markup
3755 @unnumberedsubsubsec Rotating markup
3757 All markup text can be rotated to lie at any angle by prefixing it
3758 with the @code{\rotate} command. The command takes two arguments:
3759 the angle of rotation in degrees counter-clockwise and the text to
3760 be rotated. The extents of the text are not rotated: they take
3761 their values from the extremes of the x and y coordinates of the
3762 rotated text. In the following example the
3763 @code{outside-staff-priority} property for text is set to @code{#f}
3764 to disable the automatic collision avoidance, which would push some
3765 of the text too high.
3767 @lilypond[quote,fragment,verbatim]
3768 \override TextScript.outside-staff-priority = ##f
3769 g4^\markup { \rotate #30 "a G" }
3770 b^\markup { \rotate #30 "a B" }
3771 des'^\markup { \rotate #30 "a D-Flat" }
3772 fis'^\markup { \rotate #30 "an F-Sharp" }
3775 @node Ritocchi avanzati
3776 @section Ritocchi avanzati
3777 @translationof Advanced tweaks
3779 This section discusses various approaches to fine tuning the
3780 appearance of the printed score.
3783 * Aligning objects::
3784 * Vertical grouping of grobs::
3785 * Modifying stencils::
3786 * Modifying shapes::
3787 * Modifying broken spanners::
3788 * Unpure-pure containers::
3792 Manuale di apprendimento:
3793 @rlearning{Modifica dell'output},
3794 @rlearning{Altre fonti di informazione}.
3796 Guida alla notazione:
3797 @ref{Explaining the Internals Reference},
3798 @ref{Modifying properties}.
3801 @rextend{Interfaces for programmers}.
3804 @file{scm/define-grobs.scm}.
3807 @rlsr{Tweaks and overrides}.
3809 Guida al funzionamento interno:
3810 @rinternals{All layout objects}.
3813 @node Aligning objects
3814 @subsection Aligning objects
3816 Graphical objects which support the @code{self-alignment-interface}
3817 and/or the @code{side-position-interface} can be aligned to a previously
3818 placed object in a variety of ways. For a list of these objects, see
3819 @rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
3821 All graphical objects have a reference point, a horizontal extent and a
3822 vertical extent. The horizontal extent is a pair of numbers
3823 giving the displacements from the reference point of the left and
3824 right edges, displacements to the left being negative. The vertical
3825 extent is a pair of numbers giving the displacement from the reference
3826 point to the bottom and top edges, displacements down being negative.
3828 An object's position on a staff is given by the values of the
3829 @code{X-offset} and @code{Y-offset} properties. The value of
3830 @code{X-offset} gives the displacement from the X coordinate of
3831 the reference point of the parent object, and the value of
3832 @code{Y-offset} gives the displacement from the center line of the
3833 staff. The values of @code{X-offset} and @code{Y-offset} may
3834 be set directly or may be set to be calculated by procedures in order
3835 to achieve alignment with the parent object.
3837 @warning{Many objects have special positioning considerations which
3838 cause any setting of @code{X-offset} or @code{Y-offset} to be
3839 ignored or modified, even though the object supports the
3840 @code{self-alignment-interface}. Overriding the @code{X-offset}
3841 or @code{Y-offset} properties to a fixed value causes the respective
3842 @code{self-alignment} property to be disregarded.}
3844 For example, an accidental can be repositioned vertically by setting
3845 @code{Y-offset} but any changes to @code{X-offset} have no effect.
3847 Rehearsal marks may be aligned with breakable objects such as bar
3848 lines, clef symbols, time signature symbols and key signatures. There
3849 are special properties to be found in the @code{break-aligned-interface}
3850 for positioning rehearsal marks on such objects.
3853 Guida alla notazione:
3854 @ref{Using the break-alignable-interface}.
3857 @rextend{Callback functions}.
3860 * Setting X-offset and Y-offset directly::
3861 * Using the side-position-interface::
3862 * Using the self-alignment-interface::
3863 * Using the break-alignable-interface::
3866 @node Setting X-offset and Y-offset directly
3867 @unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
3869 Numerical values may be given to the @code{X-offset} and @code{Y-offset}
3870 properties of many objects. The following example shows three
3871 notes with the default fingering position and the positions with @code{X-offset}
3872 and @code{Y-offset} modified.
3874 @lilypond[verbatim,fragment,quote]
3881 -\tweak X-offset #-1
3888 @node Using the side-position-interface
3889 @unnumberedsubsubsec Using the @code{side-position-interface}
3891 An object which supports the @code{side-position-interface} can be
3892 placed next to its parent object so that
3893 the specified edges of the two objects touch. The object may be
3894 placed above, below, to the right or to the left of the parent.
3895 The parent cannot be specified; it is determined by the order of
3896 elements in the input stream. Most objects have the associated
3897 note head as their parent.
3899 The values of the @code{side-axis} and @code{direction} properties
3900 determine where the object is to be placed, as follows:
3902 @c TODO add an example of each to the table
3904 @multitable @columnfractions .3 .3 .3
3905 @headitem @code{side-axis} @tab @code{direction} @tab
3906 @headitem property @tab property @tab Placement
3908 @item @code{0} @tab @code{-1} @tab left
3909 @item @code{0} @tab @code{1} @tab right
3910 @item @code{1} @tab @code{-1} @tab below
3911 @item @code{1} @tab @code{1} @tab above
3915 When @code{side-axis} is @code{0}, @code{X-offset} should be set to
3916 the procedure @code{ly:side-position-interface::x-aligned-side}.
3917 This procedure will return the correct value of @code{X-offset} to
3918 place the object to the left or right side of the parent according
3919 to value of @code{direction}.
3921 When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
3922 the procedure @code{ly:side-position-interface::y-aligned-side}.
3923 This procedure will return the correct value of @code{Y-offset} to
3924 place the object to the top or bottom of the parent according
3925 to value of @code{direction}.
3927 @c TODO Add examples
3929 @node Using the self-alignment-interface
3930 @unnumberedsubsubsec Using the @code{self-alignment-interface}
3932 @subsubsubheading Self-aligning objects horizontally
3934 The horizontal alignment of an object which supports the
3935 @code{self-alignment-interface} is controlled by the value of
3936 the @code{self-alignment-X} property, provided the object's
3937 @code{X-offset} property is set to
3938 @code{ly:self-alignment-interface::x-aligned-on-self}.
3939 @code{self-alignment-X} may be given any
3940 real value, in units of half the total X extent of the
3941 object. Negative values move the object to the right, positive
3942 to the left. A value of @code{0} centers the object on the
3943 reference point of its parent, a value of @w{@code{-1}} aligns the
3944 left edge of the object on the reference point of its parent,
3945 and a value of @code{1} aligns the right edge of the object on the
3946 reference point of its parent. The symbols @code{LEFT},
3947 @code{CENTER}, and @code{RIGHT} may be used instead of the values
3948 @w{@code{-1}}, @code{0}, and @code{1}, respectively.
3950 Normally the @code{\override} command would be used to modify the
3951 value of @code{self-alignment-X}, but the @code{\tweak} command
3952 can be used to separately align several annotations on a single
3955 @lilypond[quote,verbatim,fragment]
3957 -\tweak self-alignment-X #-1
3959 -\tweak self-alignment-X #0
3961 -\tweak self-alignment-X #RIGHT
3963 -\tweak self-alignment-X #-2.5
3964 ^"aligned further to the right"
3967 @subsubsubheading Self-aligning objects vertically
3969 Objects may be aligned vertically in an analogous way to aligning
3970 them horizontally if the @code{Y-offset} property is set to
3971 @code{ly:self-alignment-interface::y-aligned-on-self}. However,
3972 other mechanisms are often involved in vertical alignment: the
3973 value of @code{Y-offset} is just one variable taken into account.
3974 This may make adjusting the value of some objects tricky.
3975 The units are just half the vertical extent of the object, which
3976 is usually quite small, so quite large numbers may be required.
3977 A value of @w{@code{-1}} aligns the lower edge of the object with
3978 the reference point of the parent object, a value of @code{0}
3979 aligns the center of the object with the reference point of the
3980 parent, and a value of @code{1} aligns the top edge of the object
3981 with the reference point of the parent. The symbols @code{DOWN},
3982 @code{CENTER}, and @code{UP} may be substituted for @w{@code{-1}},
3983 @code{0}, and @code{1}, respectively.
3985 @subsubsubheading Self-aligning objects in both directions
3987 By setting both @code{X-offset} and @code{Y-offset}, an object may
3988 be aligned in both directions simultaneously.
3990 The following example shows how to adjust a fingering mark so
3991 that it nestles close to the note head.
3993 @lilypond[quote,verbatim,fragment]
3995 -\tweak self-alignment-X #0.5 % move horizontally left
3996 -\tweak Y-offset #ly:self-alignment-interface::y-aligned-on-self
3997 -\tweak self-alignment-Y #-1 % move vertically up
4002 @unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
4004 @c Cannot document as they do not seem to operate consistently on all objects -td
4005 @c TODO investigate further
4007 The @code{aligned-on-parent} procedures are used in the same way
4008 as the @code{aligned-on-self} procedures, they difference being
4009 that they permit an object to be aligned with the @emph{edges} of
4010 the parent rather than the parent's reference point. The following
4011 example shows the difference:
4015 @lilypond[verbatim,quote]
4021 @unnumberedsubsubsec Using the @code{centered-on-parent} procedures
4023 @c Cannot document as they do not seem to operate consistently on all objects -td
4024 @c TODO investigate further
4028 @c TODO The align-interface, BassFigureAlignment and VerticalAlignment
4030 @node Using the break-alignable-interface
4031 @unnumberedsubsubsec Using the @code{break-alignable-interface}
4033 @cindex align to objects
4034 @cindex break-align-symbols
4036 Rehearsal marks and bar numbers may be aligned with notation
4037 objects other than bar lines. These objects include @code{ambitus},
4038 @code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
4039 @code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
4040 @code{time-signature}.
4042 Each type of object has its own default reference point, to which
4043 rehearsal marks are aligned:
4045 @lilypond[verbatim,quote,fragment]
4046 % The rehearsal mark will be aligned to the right edge of the Clef
4047 \override Score.RehearsalMark.break-align-symbols = #'(clef)
4052 % The rehearsal mark will be aligned to the left edge of the Time Signature
4053 \override Score.RehearsalMark.break-align-symbols = #'(time-signature)
4059 % The rehearsal mark will be centered above the Breath Mark
4060 \override Score.RehearsalMark.break-align-symbols = #'(breathing-sign)
4069 A list of possible target alignment objects may be specified. If
4070 some of the objects are invisible at that point due to the setting
4071 of @code{break-visibility} or the explicit visibility settings for
4072 keys and clefs, the rehearsal mark or bar number is aligned to the
4073 first object in the list which is visible. If no objects in the
4074 list are visible the object is aligned to the bar line. If the bar
4075 line is invisible the object is aligned to the place where the bar
4078 @lilypond[verbatim,quote,fragment]
4079 % The rehearsal mark will be aligned to the right edge of the Key Signature
4080 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
4085 % The rehearsal mark will be aligned to the right edge of the Clef
4086 \set Staff.explicitKeySignatureVisibility = #all-invisible
4087 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
4092 % The rehearsal mark will be centered above the Bar Line
4093 \set Staff.explicitKeySignatureVisibility = #all-invisible
4094 \set Staff.explicitClefVisibility = #all-invisible
4095 \override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
4102 The alignment of the rehearsal mark relative to the notation object
4103 can be changed, as shown in the following example. In a score with
4104 multiple staves, this setting should be done for all the staves.
4106 @lilypond[verbatim,quote,fragment]
4107 % The RehearsalMark will be aligned with the right edge of the Key Signature
4108 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
4114 % The RehearsalMark will be centered above the Key Signature
4115 \once \override Score.KeySignature.break-align-anchor-alignment = #CENTER
4119 % The RehearsalMark will be aligned with the left edge of the Key Signature
4120 \once \override Score.KeySignature.break-align-anchor-alignment = #LEFT
4126 The rehearsal mark can also be offset to the right or left of the left
4127 edge by an arbitrary amount. The units are staff-spaces:
4129 @lilypond[verbatim,quote,fragment]
4130 % The RehearsalMark will be aligned with the left edge of the Key Signature
4131 % and then shifted right by 3.5 staff-spaces
4132 \override Score.RehearsalMark.break-align-symbols = #'(key-signature)
4133 \once \override Score.KeySignature.break-align-anchor = #3.5
4137 % The RehearsalMark will be aligned with the left edge of the Key Signature
4138 % and then shifted left by 2 staff-spaces
4139 \once \override Score.KeySignature.break-align-anchor = #-2
4146 @node Vertical grouping of grobs
4147 @subsection Vertical grouping of grobs
4149 @c TODO Expand this section
4151 The VerticalAlignment and VerticalAxisGroup grobs work together.
4152 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
4153 etc. VerticalAlignment then vertically aligns the different grobs
4154 grouped together by VerticalAxisGroup. There is usually only one
4155 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
4159 @node Modifying stencils
4160 @subsection Modifying stencils
4162 All layout objects have a @code{stencil} property which is part of
4163 the @code{grob-interface}. By default, this property is usually
4164 set to a function specific to the object that is tailor-made to
4165 render the symbol which represents it in the output. For example,
4166 the standard setting for the @code{stencil} property of the
4167 @code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
4169 The standard symbol for any object can be replaced by modifying the
4170 @code{stencil} property to reference a different, specially-written,
4171 procedure. This requires a high level of knowledge of the internal
4172 workings of LilyPond, but there is an easier way which can often
4173 produce adequate results.
4175 This is to set the @code{stencil} property to the procedure which
4176 prints text -- @code{ly:text-interface::print} -- and to add a
4177 @code{text} property to the object which is set to contain the
4178 markup text which produces the required symbol. Due to the
4179 flexibility of markup, much can be achieved -- see in particular
4180 @ref{Graphic notation inside markup}.
4182 The following example demonstrates this by changing the note head
4183 symbol to a cross within a circle.
4185 @lilypond[verbatim,quote]
4187 \once \override NoteHead.stencil = #ly:text-interface::print
4188 \once \override NoteHead.text = \markup {
4190 \halign #-0.7 \draw-circle #0.85 #0.2 ##f
4191 \musicglyph #"noteheads.s2cross"
4199 Any of the glyphs in the feta Font can be supplied to the
4200 @code{\musicglyph} markup command -- see @ref{The Feta font}.
4202 @c TODO Add inserting eps files or ref to later
4204 @c TODO Add inserting Postscript or ref to later
4207 Guida alla notazione:
4208 @ref{Graphic notation inside markup},
4209 @ref{Formatting text},
4210 @ref{Text markup commands},
4211 @ref{The Feta font}.
4214 @node Modifying shapes
4215 @subsection Modifying shapes
4218 * Modifying ties and slurs::
4221 @node Modifying ties and slurs
4222 @unnumberedsubsubsec Modifying ties and slurs
4224 @cindex slurs, modifying
4225 @cindex ties, modifying
4226 @cindex Bézier curves, control points
4227 @cindex control points, Bézier curves
4229 @code{Tie}s, @code{Slur}s, @code{PhrasingSlur}s,
4230 @code{LaissezVibrerTie}s and @code{RepeatTie}s are all drawn as
4231 third-order Bézier curves. If the shape of the tie or slur which
4232 is calculated automatically is not optimum, the shape may be
4233 modified manually in two ways:
4237 by specifying the displacements to be made to the control points
4238 of the automatically calculated Bézier curve, or
4241 by explicitly specifying the positions of the four control points
4242 required to define the wanted curve.
4245 Both methods are explained below. The first method is more suitable
4246 if only slight adjustments to the curve are required; the second may
4247 be better for creating curves which are related to just a single
4250 @subsubsubheading Cubic Bézier curves
4252 Third-order or cubic Bézier curves are defined by four control
4253 points. The first and fourth control points are precisely the
4254 starting and ending points of the curve. The intermediate two
4255 control points define the shape. Animations showing how the curve
4256 is drawn can be found on the web, but the following description
4257 may be helpful. The curve starts from the first control point
4258 heading directly towards the second, gradually bending over to
4259 head towards the third and continuing to bend over to head towards
4260 the fourth, arriving there travelling directly from the third
4261 control point. The curve is entirely contained in the
4262 quadrilateral defined by the four control points. Translations,
4263 rotations and scaling of the control points all result in exactly
4264 the same operations on the curve.
4266 @subsubsubheading Specifying displacements from current control points
4268 @cindex shaping slurs and ties
4271 In this example the automatic placement of the tie is not optimum,
4272 and @code{\tieDown} would not help.
4274 @lilypond[verbatim,quote]
4278 \relative { r4 <g' c,> <g c,> <g c,> }
4282 Adjusting the control points of the tie with @code{\shape} allows
4283 the collisions to be avoided.
4285 The syntax of @code{\shape} is
4288 [-]@code{\shape} @var{displacements} @var{item}
4291 This will reposition the control-points of @var{item} by the amounts
4292 given by @var{displacements}. The @var{displacements} argument is a
4293 list of number pairs or a list of such lists. Each element of a pair
4294 represents the displacement of one of the coordinates of a
4295 control-point. If @var{item} is a string, the result is
4296 @code{\once\override} for the specified grob type. If @var{item} is
4297 a music expression, the result is the same music expression with an
4298 appropriate tweak applied.
4300 In other words, the @code{\shape} function can act as either a
4301 @code{\once\override} command or a @code{\tweak} command depending
4302 on whether the @var{item} argument is a grob name, like @qq{Slur},
4303 or a music expression, like @qq{(}. The @var{displacements} argument
4304 specifies the displacements of the four control points as a list of
4305 four pairs of (dx . dy) values in units of staff-spaces (or a list
4306 of such lists if the curve has more than one segment).
4308 The leading hyphen is required if and only if the @code{\tweak} form
4311 So, using the same example as above and the @code{\once\override}
4312 form of @code{\shape}, this will raise the tie by half a staff-space:
4314 @lilypond[verbatim,quote]
4317 \shape #'((0 . 0.5) (0 . 0.5) (0 . 0.5) (0 . 0.5)) Tie
4321 \relative { r4 <g' c,> <g c,> <g c,> }
4325 This positioning of the tie is better, but maybe it should be raised
4326 more in the center. The following example does this, this time using
4327 the alternative @code{\tweak} form:
4329 @lilypond[verbatim,quote]
4332 e'1-\shape #'((0 . 0.5) (0 . 1) (0 . 1) (0 . 0.5)) ~ e'
4335 \relative { r4 <g' c,> <g c,> <g c,> }
4339 Changes to the horizontal positions of the control points may be made
4340 in the same way, and two different curves starting at the same
4341 musical moment may also be shaped:
4343 @lilypond[verbatim,quote,ragged-right]
4345 c''8(\( a) a'4 e c\)
4346 \shape #'((0.7 . -0.4) (0.5 . -0.4) (0.3 . -0.3) (0 . -0.2)) Slur
4347 \shape #'((0 . 0) (0 . 0.5) (0 . 0.5) (0 . 0)) PhrasingSlur
4352 The @code{\shape} function can also displace the control points of
4353 curves which stretch across line breaks. Each piece of the broken
4354 curve can be given its own list of offsets. If changes to a
4355 particular segment are not needed, the empty list can serve as a
4356 placeholder. In this example the line break makes the single slur
4359 @lilypond[verbatim,quote,ragged-right]
4367 Changing the shapes of the two halves of the slur makes it clearer
4368 that the slur continues over the line break:
4370 @lilypond[verbatim,quote,ragged-right]
4371 % () may be used as a shorthand for ((0 . 0) (0 . 0) (0 . 0) (0 . 0))
4372 % if any of the segments does not need to be changed
4375 (( 0 . 0) (0 . 0) (0 . 0) (0 . 1))
4376 ((0.5 . 1.5) (1 . 0) (0 . 0) (0 . -1.5))
4384 If an S-shaped curve is required the control points must always be
4385 adjusted manually --- LilyPond will never select such shapes
4388 @lilypond[verbatim,quote]
4390 c8( e b-> f d' a e-> g)
4391 \shape #'((0 . -1) (5.5 . -0.5) (-5.5 . -10.5) (0 . -5.5)) PhrasingSlur
4392 c8\( e b-> f d' a e-> g\)
4396 @subsubsubheading Specifying control points explicitly
4398 The coordinates of the Bézier control points are specified in units
4399 of staff-spaces. The X@tie{}coordinate is relative to the reference
4400 point of the note to which the tie or slur is attached, and the
4401 Y@tie{}coordinate is relative to the staff center line. The
4402 coordinates are specified as a list of four pairs of decimal numbers
4403 (reals). One approach is to estimate the coordinates of the two
4404 end points, and then guess the two intermediate points. The optimum
4405 values are then found by trial and error. Be aware that these values
4406 may need to be manually adjusted if any further changes are made to
4407 the music or the layout.
4409 One situation where specifying the control points explicitly is
4410 preferable to specifying displacements is when they need to be
4411 specified relative to a single note. Here is an example of this.
4412 It shows one way of indicating a slur extending into alternative
4413 sections of a volta repeat.
4415 @lilypond[verbatim,quote]
4418 \repeat volta 3 { c4 d( e f }
4423 % create a slur and move it to a new position
4424 % the <> is just an empty chord to carry the slur termination
4425 -\tweak control-points #'((-2 . 3.8) (-1 . 3.9) (0 . 4) (1 . 3.4)) ( <> )
4430 % create a slur and move it to a new position
4431 -\tweak control-points #'((-2 . 3) (-1 . 3.1) (0 . 3.2) (1 . 2.4)) ( <> )
4439 It is not possible to modify shapes of ties or slurs by changing
4440 the @code{control-points} property if there are multiple ties or slurs
4441 at the same musical moment -- the @code{\tweak} command will also not
4442 work in this case. However, the @code{tie-configuration} property of
4443 @code{TieColumn} can be overridden to set start line and direction as
4447 Guida al funzionamento interno:
4448 @rinternals{TieColumn}.
4451 @node Modifying broken spanners
4452 @subsection Modifying broken spanners
4455 * Using alterBroken::
4458 @node Using alterBroken
4459 @unnumberedsubsubsec Using @code{\alterBroken}
4461 @cindex spanners, modifying
4462 @cindex broken spanners, modifying
4463 @funindex \alterBroken
4465 When a spanner crosses a line break or breaks, each piece
4466 inherits the attributes of the original spanner. Thus, ordinary
4467 tweaking of a broken spanner applies the same modifications to
4468 each of its segments. In the example below, overriding
4469 @code{thickness} affects the slur on either side of the line
4472 @lilypond[verbatim,quote,ragged-right]
4475 \once\override Slur.thickness = 10
4482 Independently modifying the appearance of individual pieces
4483 of a broken spanner is possible with the @code{\alterBroken}
4484 command. This command can produce either an @code{\override}
4485 or a @code{\tweak} of a spanner property.
4487 The syntax for @code{\alterBroken} is
4490 [-]@code{\alterBroken} @var{property} @var{values} @var{item}
4493 The argument @var{values} is a list of values, one for each
4494 broken piece. If @var{item} is a grob name like @code{Slur} or
4495 @code{Staff.PianoPedalBracket}, the result is an @code{\override}
4496 of the specified grob type. If @var{item} is a music expression
4497 such as @qq{(} or @qq{[} the result is the same music expression
4498 with an appropriate tweak applied.
4500 The leading hyphen must be used with the @code{\tweak} form. Do
4501 not add it when @code{\alterBroken} is used as an
4504 In its @code{\override} usage, @code{\alterBroken} may be
4505 prefaced by @code{\once} or @code{\temporary} and reverted by
4506 using @code{\revert} with @var{property}.
4508 The following code applies an independent @code{\override} to
4509 each of the slur segments in the previous example:
4511 @lilypond[verbatim,quote,ragged-right]
4514 \alterBroken thickness #'(10 1) Slur
4521 The @code{\alterBroken} command may be used with any spanner
4522 object, including @code{Tie}, @code{PhrasingSlur}, @code{Beam}
4523 and @code{TextSpanner}. For example, an editor preparing a
4524 scholarly edition may wish to indicate the absence of part of a
4525 phrasing slur in a source by dashing only the segment which has
4526 been added. The following example illustrates how this can be
4527 done, in this case using the @code{\tweak} form of the command:
4529 @lilypond[verbatim,quote,ragged-right]
4530 % The empty list is conveniently used below, because it is the
4531 % default setting of dash-definition, resulting in a solid curve.
4533 c''2-\alterBroken dash-definition #'(() ((0 1.0 0.4 0.75))) \(e
4539 It is important to understand that @code{\alterBroken} will set
4540 each piece of a broken spanner to the corresponding value in
4541 @var{values}. When there are fewer values than pieces, any
4542 additional piece will be assigned the empty list. This may lead
4543 to undesired results if the layout property is not set to the
4544 empty list by default. In such cases, each segment should be
4545 assigned an appropriate value.
4548 Line breaks may occur in different places following changes in
4549 layout. Settings chosen for @code{\alterBroken} may be unsuitable
4550 for a spanner that is no longer broken or is split into more
4551 segments than before. Explicit use of @code{\break} can guard
4552 against this situation.
4554 The @code{\alterBroken} command is ineffective for spanner
4555 properties accessed before line-breaking such as
4560 @rextend{Difficult tweaks}.
4563 @node Unpure-pure containers
4564 @subsection Unpure-pure containers
4566 @cindex Scheme, pure containers
4567 @cindex Scheme, unpure containers
4568 @cindex pure containers, Scheme
4569 @cindex unpure containers, Scheme
4570 @cindex horizontal spacing, overriding
4572 Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
4573 calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
4574 Scheme function instead of a literal (i.e. a number or pair).
4576 For certain grobs, the @code{Y-extent} is based on the @code{stencil}
4577 property, overriding the stencil property of one of these will
4578 require an additional @code{Y-extent} override with an unpure-pure
4579 container. When a function overrides a @code{Y-offset} and/or
4580 @code{Y-extent} it is assumed that this will trigger line breaking
4581 calculations too early during compilation. So the function is not
4582 evaluated at all (usually returning a value of @samp{0} or
4583 @samp{'(0 . 0)}) which can result in collisions. A @q{pure} function
4584 will not affect properties, objects or grob suicides and therefore will
4585 always have its Y-axis-related evaluated correctly.
4587 Currently, there are about thirty functions that are already considered
4588 @q{pure} and Unpure-pure containers are a way to set functions not on
4589 this list as @q{pure}. The @q{pure} function is evaluated @emph{before}
4590 any line-breaking and so the horizontal spacing can be adjusted
4591 @q{in time}. The @q{unpure} function is then evaluated @emph{after}
4594 @warning{As it is difficult to always know which functions are on this
4595 list we recommend that any @q{pure} functions you create do not use
4596 @code{Beam} or @code{VerticalAlignment} grobs.}
4598 An unpure-pure container is constructed as follows;
4600 @code{(ly:make-unpure-pure-container f0 f1)}
4602 where @code{f0} is a function taking @var{n} arguments (@var{n >= 1})
4603 and the first argument must always be the grob. This is the function
4604 that gives the actual result. @var{f1} is the function being labeled
4605 as @q{pure} that takes @var{n + 2} arguments. Again, the first argument
4606 must always still be the grob but the second and third are @q{start}
4607 and @q{end} arguments.
4609 @var{start} and @var{end} are, for all intents and purposes, dummy
4610 values that only matter for @code{Spanners} (i.e @code{Hairpin} or
4611 @code{Beam}), that can return different height estimations based on a
4612 starting and ending column.
4614 The rest are the other arguments to the first function (which
4615 may be none if @var{n = 1}).
4617 The results of the second function are used as an approximation of the
4618 value needed which is then used by the first function to get the real
4619 value which is then used for fine-tuning much later during the spacing
4622 @lilypond[verbatim,quote,ragged-right]
4623 #(define (square-line-circle-space grob)
4624 (let* ((pitch (ly:event-property (ly:grob-property grob 'cause) 'pitch))
4625 (notename (ly:pitch-notename pitch)))
4626 (if (= 0 (modulo notename 2))
4627 (make-circle-stencil 0.5 0.0 #t)
4628 (make-filled-box-stencil '(0 . 1.0)
4631 squareLineCircleSpace = {
4632 \override NoteHead.stencil = #square-line-circle-space
4635 smartSquareLineCircleSpace = {
4636 \squareLineCircleSpace
4637 \override NoteHead.Y-extent =
4638 #(ly:make-unpure-pure-container
4639 ly:grob::stencil-height
4640 (lambda (grob start end) (ly:grob::stencil-height grob)))
4643 \new Voice \with { \remove "Stem_engraver" }
4645 \squareLineCircleSpace
4647 \smartSquareLineCircleSpace
4652 In the first measure, without the unpure-pure container, the spacing
4653 engine does not know the width of the note head and lets it collide with
4654 the accidentals. In the second measure, with unpure-pure containers,
4655 the spacing engine knows the width of the note heads and avoids the
4656 collision by lengthening the line accordingly.
4658 Usually for simple calculations nearly-identical functions for
4659 both the @q{unpure} and @q{pure} parts can be used, by only
4660 changing the number of arguments passed to, and the scope of, the
4661 function. This use case is frequent enough that
4662 @code{ly:make-unpure-pure-container} constructs such a second
4663 function by default when called with only one function argument.
4665 @warning{If a function is labeled as @q{pure} and it turns out not to
4666 be, the results can be unexpected.}
4669 @node Uso delle funzioni musicali
4670 @section Uso delle funzioni musicali
4671 @translationof Using music functions
4673 @c TODO -- add @seealso, etc. to these subsections
4675 Where tweaks need to be reused with different music expressions,
4676 it is often convenient to make the tweak part of a @emph{music
4677 function}. In this section, we discuss only @emph{substitution}
4678 functions, where the object is to substitute a variable into a
4679 piece of LilyPond input code. Other more complex functions are
4680 described in @rextend{Music functions}.
4683 * Substitution function syntax::
4684 * Substitution function examples::
4687 @node Substitution function syntax
4688 @subsection Substitution function syntax
4690 Making a function that substitutes a variable into LilyPond
4691 code is easy. The general form of these functions is
4695 #(define-music-function
4696 (@var{arg1} @var{arg2} @dots{})
4697 (@var{type1?} @var{type2?} @dots{})
4699 @var{@dots{}music@dots{}}
4706 @multitable @columnfractions .33 .66
4707 @item @code{@var{argN}}
4708 @tab @var{n}th argument
4710 @item @code{@var{typeN?}}
4711 @tab a scheme @emph{type predicate} for which @code{@var{argN}}
4712 must return @code{#t}.
4714 @item @code{@var{@dots{}music@dots{}}}
4715 @tab normal LilyPond input, using @code{$} (in places where only
4716 Lilypond constructs are allowed) or @code{#} (to use it as a Scheme
4717 value or music function argument or music inside of music lists) to
4722 The list of type predicates is required. Some of the most common
4723 type predicates used in music functions are:
4727 cheap-list? @emph{(use instead of }@q{list?}@emph{ for faster processing)}
4739 For a list of available type predicates, see
4740 @ref{Predefined type predicates}. User-defined type predicates
4744 Guida alla notazione:
4745 @ref{Predefined type predicates}.
4748 @rextend{Music functions}.
4751 @file{lily/music-scheme.cc},
4753 @file{scm/lily.scm}.
4756 @node Substitution function examples
4757 @subsection Substitution function examples
4759 This section introduces some substitution function examples.
4760 These are not intended to be exhaustive, but rather to demonstrate
4761 some of the possibilities of simple substitution functions.
4763 In the first example, a function is defined that simplifies
4764 setting the padding of a TextScript:
4766 @lilypond[quote,verbatim,ragged-right]
4768 #(define-music-function
4772 \once \override TextScript.padding = #padding
4776 c''4^"piu mosso" b a b
4778 c4^"piu mosso" b a b
4780 c4^"piu mosso" b a b
4784 In addition to numbers, we can use music expressions such
4785 as notes for arguments to music functions:
4787 @lilypond[quote,verbatim,ragged-right]
4789 #(define-music-function
4793 \tweak NoteHead.stencil #ly:text-interface::print
4794 \tweak NoteHead.text
4795 \markup \musicglyph #"custodes.mensural.u0"
4796 \tweak Stem.stencil ##f
4800 \relative { c'4 d e f \custosNote g }
4804 Both of those functions are simple single expressions where only
4805 the last element of a function call or override is missing. For
4806 those particular function definitions, there is a simpler
4807 alternative syntax, namely just writing out the constant part of
4808 the expression and replacing its final missing element with
4811 @lilypond[quote,verbatim,ragged-right]
4813 \once \override TextScript.padding = \etc
4816 c''4^"piu mosso" b a b
4818 c4^"piu mosso" b a b
4820 c4^"piu mosso" b a b
4824 @lilypond[quote,verbatim,ragged-right]
4826 \tweak NoteHead.stencil #ly:text-interface::print
4827 \tweak NoteHead.text
4828 \markup \musicglyph #"custodes.mensural.u0"
4829 \tweak Stem.stencil ##f
4832 \relative { c'4 d e f \custosNote g }
4836 Substitution functions with multiple arguments can be defined:
4838 @lilypond[quote,verbatim,ragged-right]
4840 #(define-music-function
4844 \once \override Score.MetronomeMark.padding = #padding
4845 \tempo \markup { \bold #tempotext }
4849 \tempo \markup { "Low tempo" }
4851 \tempoPadded #4.0 "High tempo"
4856 @c TODO: add appropriate @@ref's here.