1 @c -*- coding: utf-8; mode: texinfo; -*-
2 @c This file is part of lilypond.tely
4 Translation of GIT committish: FILL-IN-HEAD-COMMITTISH
6 When revising a translation, copy the HEAD committish of the
7 version that you are working on. See TRANSLATION for details.
10 @node Changing defaults
11 @chapter Changing defaults
14 The purpose of LilyPond's design is to provide the finest output
15 quality as a default. Nevertheless, it may happen that you need to
16 change this default layout. The layout is controlled through a large
17 number of proverbial @q{knobs and switches.} This chapter does not
18 list each and every knob. Rather, it outlines what groups of controls
19 are available and explains how to lookup which knob to use for a
23 @cindex Program reference
25 The controls available for tuning are described in a separate
28 Program reference manual.
31 @ref{Top,Program reference,,lilypond-internals}.
34 lists all different variables, functions and options available in
35 LilyPond. It is written as a HTML document, which is available
36 @c leave the @uref as one long line.
37 @uref{http://@/lilypond@/.org/@/doc/@/stable/@/Documentation/@/user/@/lilypond@/-internals/,on@/-line},
38 but is also included with the LilyPond documentation package.
40 There are four areas where the default settings may be changed:
44 Automatic notation: changing the automatic creation of notation
45 elements. For example, changing the beaming rules.
48 Output: changing the appearance of individual
49 objects. For example, changing stem directions or the location of
53 Context: changing aspects of the translation from music events to
54 notation. For example, giving each staff a separate time signature.
57 Page layout: changing the appearance of the spacing, line
58 breaks, and page dimensions. These modifications are discussed
59 in @ref{Non-musical notation}, and @ref{Spacing issues}.
62 Internally, LilyPond uses Scheme (a LISP dialect) to provide
63 infrastructure. Overriding layout decisions in effect accesses the
64 program internals, which requires Scheme input. Scheme elements are
65 introduced in a @code{.ly} file with the hash mark
66 @code{#}.@footnote{@ref{Scheme tutorial}, contains a short tutorial
67 on entering numbers, lists, strings, and symbols in Scheme.}
71 * Automatic notation::
72 * Interpretation contexts::
73 * The \override command::
77 @node Automatic notation
78 @section Automatic notation
80 This section describes how to change the way that accidentals and
81 beams are automatically displayed.
84 * Automatic accidentals::
85 * Setting automatic beam behavior::
88 @node Automatic accidentals
89 @subsection Automatic accidentals
90 @cindex Automatic accidentals
92 Common rules for typesetting accidentals have been placed in a
93 function. This function is called as follows
95 @funindex set-accidental-style
97 #(set-accidental-style 'STYLE #('CONTEXT#))
100 The function can take two arguments: the name of the accidental style,
101 and an optional argument that denotes the context that should be
102 changed. If no context name is supplied, @code{Staff} is the default,
103 but you may wish to apply the accidental style to a single @code{Voice}
106 @c TODO: we should create a very clear example, and show every
107 @c accidental style on that example (with the example specially
108 @c constructed so that it illustrates all the differences). -gp
110 The following accidental styles are supported
113 This is the default typesetting behavior. It corresponds
114 to 18th century common practice: Accidentals are
115 remembered to the end of the measure in which they occur and
116 only on their own octave.
119 The normal behavior is to remember the accidentals on
120 Staff-level. This variable, however, typesets accidentals
121 individually for each voice. Apart from that, the rule is similar to
124 As a result, accidentals from one voice do not get canceled in other
125 voices, which is often an unwanted result
127 @lilypond[quote,ragged-right,relative=1,fragment,verbatim]
129 #(set-accidental-style 'voice)
136 The @code{voice} option should be used if the voices
137 are to be read solely by individual musicians. If the staff is to be
138 used by one musician (e.g., a conductor) then
139 @code{modern} or @code{modern-cautionary}
140 should be used instead.
143 @funindex modern style accidentals
144 This rule corresponds to the common practice in the 20th century. This rule
145 prints the same accidentals as @code{default}, but temporary
146 accidentals also are canceled in other octaves. Furthermore,
147 in the same octave, they also get canceled in the following
150 @lilypond[quote,ragged-right,fragment,verbatim]
151 #(set-accidental-style 'modern)
152 cis' c'' cis'2 | c'' c'
155 @item @code{modern-cautionary}
156 @funindex modern-cautionary
157 This rule is similar to @code{modern}, but the @q{extra} accidentals
158 (the ones not typeset by @code{default}) are typeset as cautionary
159 accidentals. They are printed in reduced size or with parentheses
160 @lilypond[quote,ragged-right,fragment,verbatim]
161 #(set-accidental-style 'modern-cautionary)
162 cis' c'' cis'2 | c'' c'
165 @funindex modern-voice
167 This rule is used for multivoice accidentals to be read both by musicians
168 playing one voice and musicians playing all voices. Accidentals are
169 typeset for each voice, but they @emph{are} canceled across voices in
170 the same @internalsref{Staff}.
172 @funindex modern-voice-cautionary
173 @item modern-voice-cautionary
174 This rule is the same as @code{modern-voice}, but with the extra
175 accidentals (the ones not typeset by @code{voice}) typeset
176 as cautionaries. Even though all accidentals typeset by
177 @code{default} @emph{are} typeset by this variable,
178 some of them are typeset as cautionaries.
181 @funindex piano accidentals
182 This rule reflects 20th century practice for piano notation. Very similar to
183 @code{modern} but accidentals also get canceled
184 across the staves in the same @internalsref{GrandStaff} or
185 @internalsref{PianoStaff}.
187 @item piano-cautionary
188 @funindex #(set-accidental-style 'piano-cautionary)
189 Same as @code{#(set-accidental-style 'piano)} but with the extra
190 accidentals typeset as cautionaries.
193 @funindex no-reset accidental style
194 This is the same as @code{default} but with accidentals lasting
195 @q{forever} and not only until the next measure
196 @lilypond[quote,ragged-right,fragment,verbatim,relative=1]
197 #(set-accidental-style 'no-reset)
202 This is sort of the opposite of @code{no-reset}: Accidentals
203 are not remembered at all -- and hence all accidentals are
204 typeset relative to the key signature, regardless of what was
207 @lilypond[quote,ragged-right,fragment,verbatim,relative=1]
208 #(set-accidental-style 'forget)
209 \key d\major c4 c cis cis d d dis dis
216 Program reference: @internalsref{Accidental_engraver},
217 @internalsref{Accidental}, and @internalsref{AccidentalPlacement}.
222 Simultaneous notes are considered to be entered in sequential
223 mode. This means that in a chord the accidentals are typeset as if the
224 notes in the chord happen one at a time, in the order in which
225 they appear in the input file. This is a problem when accidentals
226 in a chord depend on each other,
227 which does not happen for the default accidental style. The problem
228 can be solved by manually inserting @code{!} and @code{?} for the
232 @node Setting automatic beam behavior
233 @subsection Setting automatic beam behavior
235 @funindex autoBeamSettings
236 @funindex (end * * * *)
237 @funindex (begin * * * *)
238 @cindex automatic beams, tuning
239 @cindex tuning automatic beaming
241 @c [TODO: use \applyContext]
243 In normal time signatures, automatic beams can start on any note but can
244 only end in a few positions within the measure: beams can end on a beat,
245 or at durations specified by the properties in
246 @code{autoBeamSettings}. The properties in @code{autoBeamSettings}
247 consist of a list of rules for where beams can begin and end. The
248 default @code{autoBeamSettings} rules are defined in
249 @file{scm/@/auto@/-beam@/.scm}.
251 In order to add a rule to the list, use
253 #(override-auto-beam-setting '(be p q n m) a b [context])
258 @item @code{be} is either "begin" or "end".
260 @item @code{p/q} is the duration of the note for which you want
261 to add a rule. A beam is considered to have the duration of its
262 shortest note. Set @code{p} and @code{q} to @code{'*'} to
263 have this apply to any beam.
265 @item @code{n/m} is the time signature to which
266 this rule should apply. Set @code{n} and @code{m} to @code{'*'}
267 to have this apply in any time signature.
269 @item @code{a/b} is the position in the bar at which the beam should
272 @item @code{context} is optional, and it specifies the context at which
273 the change should be made. The default is @code{'Voice}.
274 @code{#(score-override-auto-beam-setting '(A B C D) E F)} is equivalent to
275 @code{#(override-auto-beam-setting '(A B C D) E F 'Score)}.
279 For example, if automatic beams should always end on the first quarter
283 #(override-auto-beam-setting '(end * * * *) 1 4)
286 You can force the beam settings to only take effect on beams whose shortest
287 note is a certain duration
289 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
291 #(override-auto-beam-setting '(end 1 16 * *) 1 16)
293 a32 a a a a16 a a a a a |
294 #(override-auto-beam-setting '(end 1 32 * *) 1 16)
295 a32 a a a a16 a a a a a |
298 You can force the beam settings to only take effect in certain time
301 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
303 #(override-auto-beam-setting '(end * * 5 8) 2 8)
311 You can also remove a previously set beam-ending rule by using
314 #(revert-auto-beam-setting '(be p q n m) a b [context])
318 be, p, q, n, m, a, b and context are the same as above. Note that the
319 default rules are specified in @file{scm/@/auto@/-beam@/.scm},
320 so you can revert rules that you did not explicitly create.
322 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
324 a16 a a a a a a a a a a a a a a a
325 #(revert-auto-beam-setting '(end 1 16 4 4) 1 4)
326 a16 a a a a a a a a a a a a a a a
329 The rule in a revert-auto-beam-setting statement must exactly match the
330 original rule. That is, no wildcard expansion is taken into account.
332 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
334 #(override-auto-beam-setting '(end 1 16 1 4) 1 8)
336 #(revert-auto-beam-setting '(end 1 16 * *) 1 8) % this won't revert it!
338 #(revert-auto-beam-setting '(end 1 16 1 4) 1 8) % this will
344 @c TODO: old material -- not covered by above stuff, I think.
345 If automatic beams should end on every quarter in 5/4 time, specify
348 #(override-auto-beam-setting '(end * * * *) 1 4 'Staff)
349 #(override-auto-beam-setting '(end * * * *) 1 2 'Staff)
350 #(override-auto-beam-setting '(end * * * *) 3 4 'Staff)
351 #(override-auto-beam-setting '(end * * * *) 5 4 'Staff)
355 The same syntax can be used to specify beam starting points. In this
356 example, automatic beams can only end on a dotted quarter note
358 #(override-auto-beam-setting '(end * * * *) 3 8)
359 #(override-auto-beam-setting '(end * * * *) 1 2)
360 #(override-auto-beam-setting '(end * * * *) 7 8)
362 In 4/4 time signature, this means that automatic beams could end only on
363 3/8 and on the fourth beat of the measure (after 3/4, that is 2 times
364 3/8, has passed within the measure).
366 If any unexpected beam behaviour occurs, check the default automatic beam
367 settings in @file{scm/@/auto@/-beam@/.scm}
368 for possible interference, because the beam
369 endings defined there will still apply on top of your own overrides. Any
370 unwanted endings in the default vales must be reverted for your time
373 For example, to typeset @code{(3 4 3 2)}-beam endings in 12/8, begin
377 %%% revert default values in scm/auto-beam.scm regarding 12/8 time
378 #(revert-auto-beam-setting '(end * * 12 8) 3 8)
379 #(revert-auto-beam-setting '(end * * 12 8) 3 4)
380 #(revert-auto-beam-setting '(end * * 12 8) 9 8)
383 #(override-auto-beam-setting '(end 1 8 12 8) 3 8)
384 #(override-auto-beam-setting '(end 1 8 12 8) 7 8)
385 #(override-auto-beam-setting '(end 1 8 12 8) 10 8)
388 @cindex automatic beam generation
390 @funindex autoBeaming
393 If beams are used to indicate melismata in songs, then automatic
394 beaming should be switched off with @code{\autoBeamOff}.
399 @funindex \autoBeamOff
401 @funindex \autoBeamOn
406 Beaming patterns may be altered with the @code{beatGrouping} property,
408 @lilypond[quote,verbatim,relative=2,fragment,ragged-right]
410 \set beatGrouping = #'(2 3)
412 \set beatGrouping = #'(3 2)
419 If a score ends while an automatic beam has not been ended and is
420 still accepting notes, this last beam will not be typeset at all. The
421 same holds polyphonic voices, entered with @code{<< @dots{} \\ @dots{}
422 >>}. If a polyphonic voice ends while an automatic beam is still
423 accepting notes, it is not typeset.
426 @node Interpretation contexts
427 @section Interpretation contexts
429 This section describes what contexts are, and how to modify them.
432 * Contexts explained::
433 * Creating contexts::
434 * Changing context properties on the fly::
435 * Modifying context plug-ins::
436 * Layout tunings within contexts::
437 * Changing context default settings::
438 * Defining new contexts::
439 * Aligning contexts::
440 * Vertical grouping of grobs::
444 @node Contexts explained
445 @subsection Contexts explained
447 When music is printed, a lot of notational elements must be added to the
448 output. For example, compare the input and output of the following example:
450 @lilypond[quote,verbatim,relative=2,fragment]
454 The input is rather sparse, but in the output, bar lines, accidentals,
455 clef, and time signature are added. LilyPond @emph{interprets} the
456 input. During this step, the musical information is inspected in time
457 order, similar to reading a score from left to right. While reading
458 the input, the program remembers where measure boundaries are, and which
459 pitches require explicit accidentals. This information can be presented on
460 several levels. For example, the effect of an accidental is limited
461 to a single staff, while a bar line must be synchronized across the
464 Within LilyPond, these rules and bits of information are grouped in
465 @emph{Contexts}. Some examples of contexts are @context{Voice},
466 @context{Staff}, and @context{Score}. They are hierarchical, for
467 example: a @context{Staff} can contain many @context{Voice}s, and a
468 @context{Score} can contain many @context{Staff} contexts.
471 @image{context-example,5cm,,}
474 Each context has the responsibility for enforcing some notation rules,
475 creating some notation objects and maintaining the associated
476 properties. For example, the @context{Voice} context may introduce an
477 accidental and then the @context{Staff} context maintains the rule to
478 show or suppress the accidental for the remainder of the measure. The
479 synchronization of bar lines is handled at @context{Score} context.
481 However, in some music we may not want the bar lines to be
482 synchronized -- consider a polymetric score in 4/4 and 3/4 time. In
483 such cases, we must modify the default settings of the @context{Score}
484 and @context{Staff} contexts.
486 For very simple scores, contexts are created implicitly, and you need
487 not be aware of them. For larger pieces, such as anything with more
488 than one staff, they must be
489 created explicitly to make sure that you get as many staves as you
490 need, and that they are in the correct order. For typesetting pieces
491 with specialized notation, it can be useful to modify existing or
492 to define new contexts.
495 A complete description of all available contexts is in the program
498 @internalsref{Contexts}.
501 Translation @arrow{} Context.
504 @c [TODO: describe propagation]
507 @node Creating contexts
508 @subsection Creating contexts
510 For scores with only one voice and one staff, contexts are
511 created automatically. For more complex scores, it is necessary to
512 create them by hand. There are three commands that do this.
517 The easiest command is @code{\new}, and it also the quickest to type.
518 It is prepended to a music expression, for example
522 @cindex Context, creating
525 \new @var{type} @var{music expression}
529 where @var{type} is a context name (like @code{Staff} or
530 @code{Voice}). This command creates a new context, and starts
531 interpreting the @var{music expression} with that.
533 A practical application of @code{\new} is a score with many
534 staves. Each part that should be on its own staff, is preceded with
537 @lilypond[quote,verbatim,relative=2,ragged-right,fragment]
544 The @code{\new} command may also give a name to the context,
547 \new @var{type} = @var{id} @var{music}
549 However, this user specified name is only used if there is no other
550 context already earlier with the same name.
556 Like @code{\new}, the @code{\context} command also directs a music
557 expression to a context object, but gives the context an explicit name. The
561 \context @var{type} = @var{id} @var{music}
564 This form will search for an existing context of type @var{type}
565 called @var{id}. If that context does not exist yet, a new
566 context with the specified name is created. This is useful if
567 the context is referred to later on. For example, when
568 setting lyrics the melody is in a named context
571 \context Voice = "@b{tenor}" @var{music}
575 so the texts can be properly aligned to its notes,
578 \new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
583 Another possible use of named contexts is funneling two different
584 music expressions into one context. In the following example,
585 articulations and notes are entered separately,
589 arts = @{ s4-. s4-> @}
592 They are combined by sending both to the same @context{Voice} context,
596 \new Staff \context Voice = "A" \music
597 \context Voice = "A" \arts
600 @lilypond[quote,ragged-right]
604 \new Staff \context Voice = "A" \music
605 \context Voice = "A" \arts
609 With this mechanism, it is possible to define an Urtext (original
610 edition), with the option to put several distinct articulations on the
613 @cindex creating contexts
616 The third command for creating contexts is
618 \context @var{type} @var{music}
623 This is similar to @code{\context} with @code{= @var{id}}, but matches
624 any context of type @var{type}, regardless of its given name.
626 This variant is used with music expressions that can be interpreted at
627 several levels. For example, the @code{\applyOutput} command (see
628 @ref{Running a function on all layout objects}). Without an explicit
629 @code{\context}, it is usually applied to @context{Voice}
632 \applyOutput #'@var{context} #@var{function} % apply to Voice
635 To have it interpreted at the @context{Score} or @context{Staff} level use
639 \applyOutput #'Score #@var{function}
640 \applyOutput #'Staff #@var{function}
646 @node Changing context properties on the fly
647 @subsection Changing context properties on the fly
651 @cindex changing properties
653 Each context can have different @emph{properties}, variables contained
654 in that context. They can be changed during the interpretation step.
655 This is achieved by inserting the @code{\set} command in the music,
658 \set @var{context}.@var{prop} = #@var{value}
662 @lilypond[quote,verbatim,relative=2,fragment]
664 \set Score.skipBars = ##t
668 This command skips measures that have no notes. The result is that
669 multi-rests are condensed. The value assigned is a Scheme object. In
670 this case, it is @code{#t}, the boolean True value.
672 If the @var{context} argument is left out, then the current bottom-most
673 context (typically @context{ChordNames}, @context{Voice}, or
674 @context{Lyrics}) is used. In this example,
676 @lilypond[quote,verbatim,relative=2,fragment]
678 \set autoBeaming = ##f
683 the @var{context} argument to @code{\set} is left out, so automatic
684 beaming is switched off in the current @internalsref{Voice}. Note that
685 the bottom-most context does not always contain the property that you
686 wish to change -- for example, attempting to set the @code{skipBars}
687 property (of the bottom-most context, in this case @code{Voice}) will
690 @lilypond[quote,verbatim,relative=2,fragment]
696 Contexts are hierarchical, so if a bigger context was specified, for
697 example @context{Staff}, then the change would also apply to all
698 @context{Voice}s in the current stave. The change is applied
699 @q{on-the-fly}, during the music, so that the setting only affects the
700 second group of eighth notes.
704 There is also an @code{\unset} command,
706 \unset @var{context}.@var{prop}
710 which removes the definition of @var{prop}. This command removes
711 the definition only if it is set in @var{context}, so
714 \set Staff.autoBeaming = ##f
718 introduces a property setting at @code{Staff} level. The setting also
719 applies to the current @code{Voice}. However,
722 \unset Voice.autoBeaming
726 does not have any effect. To cancel this setting, the @code{\unset}
727 must be specified on the same level as the original @code{\set}. In
728 other words, undoing the effect of @code{Staff.autoBeaming = ##f}
731 \unset Staff.autoBeaming
734 Like @code{\set}, the @var{context} argument does not have to be
735 specified for a bottom context, so the two statements
738 \set Voice.autoBeaming = ##t
739 \set autoBeaming = ##t
747 Settings that should only apply to a single time-step can be entered
748 with @code{\once}, for example in
750 @lilypond[quote,verbatim,relative=2,fragment]
752 \once \set fontSize = #4.7
757 the property @code{fontSize} is unset automatically after the second
760 A full description of all available context properties is in the
761 program reference, see
763 @internalsref{Tunable context properties}.
766 Translation @arrow{} Tunable context properties.
770 @node Modifying context plug-ins
771 @subsection Modifying context plug-ins
773 Notation contexts (like @code{Score} and @code{Staff}) not only
775 they also contain plug-ins called @q{engravers} that create notation
776 elements. For example, the @code{Voice} context contains a
777 @code{Note_head_engraver} and the @code{Staff} context contains a
778 @code{Key_signature_engraver}.
780 For a full a description of each plug-in, see
782 @internalsref{Engravers}.
785 Program reference @arrow Translation @arrow{} Engravers.
787 Every context described in
789 @internalsref{Contexts}
792 Program reference @arrow Translation @arrow{} Context.
794 lists the engravers used for that context.
797 It can be useful to shuffle around these plug-ins. This is done by
798 starting a new context with @code{\new} or @code{\context}, and
804 \new @var{context} \with @{
817 where the @dots{} should be the name of an engraver. Here is a simple
818 example which removes @code{Time_signature_engraver} and
819 @code{Clef_engraver} from a @code{Staff} context,
821 @lilypond[quote,relative=1,verbatim,fragment]
827 \remove "Time_signature_engraver"
828 \remove "Clef_engraver"
835 In the second staff there are no time signature or clef symbols. This
836 is a rather crude method of making objects disappear since it will affect
837 the entire staff. This method also influences the spacing, which may or
838 may not be desirable. A more
839 sophisticated method of blanking objects is shown in @ref{Common tweaks}.
841 The next example shows a practical application. Bar lines and time
842 signatures are normally synchronized across the score. This is done
843 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
844 This plug-in keeps an administration of time signature, location
845 within the measure, etc. By moving thes engraver from @code{Score} to
846 @code{Staff} context, we can have a score where each staff has its own
849 @cindex polymetric scores
850 @cindex Time signatures, multiple
852 @lilypond[quote,relative=1,ragged-right,verbatim,fragment]
854 \remove "Timing_translator"
855 \remove "Default_bar_line_engraver"
858 \consists "Timing_translator"
859 \consists "Default_bar_line_engraver"
865 \consists "Timing_translator"
866 \consists "Default_bar_line_engraver"
875 @node Layout tunings within contexts
876 @subsection Layout tunings within contexts
878 Each context is responsible for creating certain types of graphical
879 objects. The settings used for printing these objects are also stored by
880 context. By changing these settings, the appearance of objects can be
883 The syntax for this is
886 \override @var{context}.@var{name} #'@var{property} = #@var{value}
889 Here @var{name} is the name of a graphical object, like @code{Stem} or
890 @code{NoteHead}, and @var{property} is an internal variable of the
891 formatting system (@q{grob property} or @q{layout property}). The latter is a
892 symbol, so it must be quoted. The subsection @ref{Constructing a
893 tweak}, explains what to fill in for @var{name}, @var{property}, and
894 @var{value}. Here we only discuss the functionality of this command.
899 \override Staff.Stem #'thickness = #4.0
903 makes stems thicker (the default is 1.3, with staff line thickness as a
904 unit). Since the command specifies @context{Staff} as context, it only
905 applies to the current staff. Other staves will keep their normal
906 appearance. Here we see the command in action:
908 @lilypond[quote,verbatim,relative=2,fragment]
910 \override Staff.Stem #'thickness = #4.0
916 The @code{\override} command changes the definition of the @code{Stem}
917 within the current @context{Staff}. After the command is interpreted
918 all stems are thickened.
920 Analogous to @code{\set}, the @var{context} argument may be left out,
921 causing the default context @context{Voice} to be used. Adding
922 @code{\once} applies the change during one timestep only.
924 @lilypond[quote,fragment,verbatim,relative=2]
926 \once \override Stem #'thickness = #4.0
931 The @code{\override} must be done before the object is
932 started. Therefore, when altering @emph{Spanner} objects such as slurs
933 or beams, the @code{\override} command must be executed at the moment
934 when the object is created. In this example,
936 @lilypond[quote,fragment,verbatim,relative=2]
937 \override Slur #'thickness = #3.0
939 \override Beam #'thickness = #0.6
944 the slur is fatter but the beam is not. This is because the command for
945 @code{Beam} comes after the Beam is started, so it has no effect.
947 Analogous to @code{\unset}, the @code{\revert} command for a context
948 undoes an @code{\override} command; like with @code{\unset}, it only
949 affects settings that were made in the same context. In other words, the
950 @code{\revert} in the next example does not do anything.
953 \override Voice.Stem #'thickness = #4.0
954 \revert Staff.Stem #'thickness
957 Some tweakable options are called @q{subproperties} and reside inside
958 properties. To tweak those, use commands of the form
960 @c leave this as a long long
962 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
969 \override Stem #'details #'beamed-lengths = #'(4 4 3)
975 Internals: @internalsref{OverrideProperty}, @internalsref{RevertProperty},
976 @internalsref{PropertySet}, @internalsref{Backend}, and
977 @internalsref{All layout objects}.
982 The back-end is not very strict in type-checking object properties.
983 Cyclic references in Scheme values for properties can cause hangs
987 @node Changing context default settings
988 @subsection Changing context default settings
990 The adjustments of the previous subsections (@ref{Changing context
991 properties on the fly}, @ref{Modifying context plug-ins}, and
992 @ref{Layout tunings within contexts}) can also be entered separately
993 from the music in the @code{\layout} block,
1002 \override Stem #'thickness = #4.0
1003 \remove "Time_signature_engraver"
1008 The @code{\Staff} command brings in the existing definition of the
1009 staff context so that it can be modified.
1014 \override Stem #'thickness = #4.0
1015 \remove "Time_signature_engraver"
1019 affect all staves in the score. Other contexts can be modified
1022 The @code{\set} keyword is optional within the @code{\layout} block, so
1038 It is not possible to collect context changes in a variable and apply
1039 them to a @code{\context} definition by referring to that variable.
1041 The @code{\RemoveEmptyStaffContext} will overwrite your current
1042 @code{\Staff} settings. If you wish to change the defaults for a
1043 staff which uses @code{\RemoveEmptyStaffContext}, you must do so
1044 after calling @code{\RemoveemptyStaffContext}, ie
1049 \RemoveEmptyStaffContext
1051 \override Stem #'thickness = #4.0
1057 @node Defining new contexts
1058 @subsection Defining new contexts
1060 Specific contexts, like @context{Staff} and @code{Voice}, are made of
1061 simple building blocks. It is possible to create new types of
1062 contexts with different combinations of engraver plug-ins.
1064 The next example shows how to build a different type of
1065 @context{Voice} context from scratch. It will be similar to
1066 @code{Voice}, but only prints centered slash noteheads. It can be used
1067 to indicate improvisation in jazz pieces,
1069 @lilypond[quote,ragged-right]
1070 \layout { \context {
1072 \type "Engraver_group"
1073 \consists "Note_heads_engraver"
1074 \consists "Text_engraver"
1075 \consists Pitch_squash_engraver
1076 squashedPosition = #0
1077 \override NoteHead #'style = #'slash
1078 \override Stem #'transparent = ##t
1082 \accepts "ImproVoice"
1086 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1087 c4 c^"undress" c_"while playing :)" c }
1093 These settings are defined within a @code{\context} block inside a
1094 @code{\layout} block,
1104 In the following discussion, the example input shown should go in place
1105 of the @dots{} in the previous fragment.
1107 First it is necessary to define a name for the new context:
1113 Since it is similar to the @context{Voice}, we want commands that work
1114 on (existing) @context{Voice}s to remain working. This is achieved by
1115 giving the new context an alias @context{Voice},
1121 The context will print notes and instructive texts, so we need to add
1122 the engravers which provide this functionality,
1125 \consists Note_heads_engraver
1126 \consists Text_engraver
1129 but we only need this on the center line,
1132 \consists Pitch_squash_engraver
1133 squashedPosition = #0
1136 The @internalsref{Pitch_squash_engraver} modifies note heads (created
1137 by @internalsref{Note_heads_engraver}) and sets their vertical
1138 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
1141 The notes look like a slash, and have no stem,
1144 \override NoteHead #'style = #'slash
1145 \override Stem #'transparent = ##t
1148 All these plug-ins have to cooperate, and this is achieved with a
1149 special plug-in, which must be marked with the keyword @code{\type}.
1150 This should always be @internalsref{Engraver_group},
1153 \type "Engraver_group"
1156 Put together, we get
1161 \type "Engraver_group"
1162 \consists "Note_heads_engraver"
1163 \consists "Text_engraver"
1164 \consists Pitch_squash_engraver
1165 squashedPosition = #0
1166 \override NoteHead #'style = #'slash
1167 \override Stem #'transparent = ##t
1173 Contexts form hierarchies. We want to hang the @context{ImproVoice}
1174 under @context{Staff}, just like normal @code{Voice}s. Therefore, we
1175 modify the @code{Staff} definition with the @code{\accepts}
1186 The opposite of @code{\accepts} is @code{\denies},
1187 which is sometimes needed when reusing existing context definitions.
1189 Putting both into a @code{\layout} block, like
1199 \accepts "ImproVoice"
1204 Then the output at the start of this subsection can be entered as
1212 c c_"while playing :)"
1219 @node Aligning contexts
1220 @subsection Aligning contexts
1222 New contexts may be aligned above or below exisiting contexts. This
1223 could be useful in setting up a vocal staff (@ref{Vocal ensembles}) and
1227 @findex alignAboveContext
1228 @findex alignBelowContext
1230 @lilypond[quote,ragged-right]
1231 ossia = { f4 f f f }
1233 \relative c' \new Staff = "main" {
1236 \new Staff \with {alignAboveContext=main} \ossia
1237 { d8 f d f d f d f }
1244 @node Vertical grouping of grobs
1245 @subsection Vertical grouping of grobs
1247 The VerticalAlignment and VerticalAxisGroup grobs work together.
1248 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
1249 etc. VerticalAlignment then vertically aligns the different grobs
1250 grouped together by VerticalAxisGroup. There is usually only one
1251 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
1255 @node The \override command
1256 @section The @code{\override} command
1258 In the previous section, we have already touched on a command that
1259 changes layout details: the @code{\override} command. In this section,
1260 we will look in more detail at how to use the command in practice. The
1261 general syntax of this command is:
1264 \override @var{context}.@var{layout_object} #'@var{layout_property} = #@var{value}
1267 This will set the @var{layout_property} of the specified @var{layout_object},
1268 which is a member of the @var{context}, to the @var{value}.
1271 * Constructing a tweak::
1272 * Navigating the program reference::
1273 * Layout interfaces::
1274 * Determining the grob property::
1275 * Objects connected to the input::
1276 * Using Scheme code instead of \tweak::
1277 * \set versus \override::
1278 * Difficult tweaks::
1283 @node Constructing a tweak
1284 @subsection Constructing a tweak
1286 Commands which change output generally look like
1289 \override Voice.Stem #'thickness = #3.0
1293 To construct this tweak we must determine these bits of information:
1296 @item the context: here @context{Voice}.
1297 @item the layout object: here @code{Stem}.
1298 @item the layout property: here @code{thickness}.
1299 @item a sensible value: here @code{3.0}.
1302 Some tweakable options are called @q{subproperties} and reside inside
1303 properties. To tweak those, use commands in the form
1306 \override Stem #'details #'beamed-lengths = #'(4 4 3)
1309 @cindex internal documentation
1310 @cindex finding graphical objects
1311 @cindex graphical object descriptions
1314 @cindex internal documentation
1316 For many properties, regardless of the data type of the property, setting the
1317 property to false ( @code{##f} ) will result in turning it off, causing
1318 Lilypond to ignore that property entirely. This is particularly useful for
1319 turning off grob properties which may otherwise be causing problems.
1321 We demonstrate how to glean this information from the notation manual
1322 and the program reference.
1327 @node Navigating the program reference
1328 @subsection Navigating the program reference
1330 Suppose we want to move the fingering indication in the fragment
1333 @lilypond[quote,fragment,relative=2,verbatim]
1339 If you visit the documentation on fingering instructions (in
1340 @ref{Fingering instructions}), you will notice:
1345 Program reference: @internalsref{Fingering}.
1350 @c outdated info; probably will delete.
1352 This fragment points to two parts of the program reference: a page
1353 on @code{FingerEvent} and one on @code{Fingering}.
1355 The page on @code{FingerEvent} describes the properties of the music
1356 expression for the input @code{-2}. The page contains many links
1357 forward. For example, it says
1360 Accepted by: @internalsref{Fingering_engraver},
1364 That link brings us to the documentation for the Engraver, the
1368 This engraver creates the following layout objects: @internalsref{Fingering}.
1371 In other words, once the @code{FingerEvent}s are interpreted, the
1372 @code{Fingering_engraver} plug-in will process them.
1376 @c I can't figure out what this is supposed to mean. -gp
1378 The @code{Fingering_engraver} is also listed to create
1379 @internalsref{Fingering} objects,
1381 @c old info? it doesn't make any sense to me with our current docs.
1383 second bit of information listed under @b{See also} in the Notation
1388 The programmer's reference is available as an HTML document. It is
1389 highly recommended that you read it in HTML form, either online or
1390 by downloading the HTML documentation. This section will be much more
1391 difficult to understand if you are using the
1395 Follow the link to @internalsref{Fingering}. At the top of the
1399 Fingering objects are created by: @internalsref{Fingering_engraver} and
1400 @internalsref{New_fingering_engraver}.
1403 By following related links inside the program reference, we can follow the
1404 flow of information within the program:
1408 @item @internalsref{Fingering}:
1409 @internalsref{Fingering} objects are created by:
1410 @internalsref{Fingering_engraver}
1412 @item @internalsref{Fingering_engraver}:
1413 Music types accepted: @internalsref{fingering-event}
1415 @item @internalsref{fingering-event}:
1416 Music event type @code{fingering-event} is in Music expressions named
1417 @internalsref{FingerEvent}
1420 This path goes against the flow of information in the program: it
1421 starts from the output, and ends at the input event. You could
1422 also start at an input event, and read with the flow of
1423 information, eventually ending up at the output object(s).
1425 The program reference can also be browsed like a normal document. It
1426 contains chapters on
1428 @internalsref{Music definitions},
1431 @code{Music definitions}
1433 on @internalsref{Translation}, and the @internalsref{Backend}. Every
1434 chapter lists all the definitions used and all properties that may be
1438 @node Layout interfaces
1439 @subsection Layout interfaces
1441 @cindex interface, layout
1442 @cindex layout interface
1445 The HTML page that we found in the previous section describes the
1446 layout object called @internalsref{Fingering}. Such an object is a
1447 symbol within the score. It has properties that store numbers (like
1448 thicknesses and directions), but also pointers to related objects. A
1449 layout object is also called a @emph{Grob}, which is short for Graphical
1450 Object. For more details about Grobs, see @internalsref{grob-interface}.
1452 The page for @code{Fingering} lists the definitions for the
1453 @code{Fingering} object. For example, the page says
1456 @code{padding} (dimension, in staff space):
1462 which means that the number will be kept at a distance of at least 0.5
1466 Each layout object may have several functions as a notational or
1467 typographical element. For example, the Fingering object
1468 has the following aspects
1472 Its size is independent of the horizontal spacing, unlike slurs or beams.
1475 It is a piece of text. Granted, it is usually a very short text.
1478 That piece of text is typeset with a font, unlike slurs or beams.
1481 Horizontally, the center of the symbol should be aligned to the
1482 center of the notehead.
1485 Vertically, the symbol is placed next to the note and the staff.
1488 The vertical position is also coordinated with other superscript
1489 and subscript symbols.
1492 Each of these aspects is captured in so-called @emph{interface}s,
1493 which are listed on the @internalsref{Fingering} page at the bottom
1496 This object supports the following interfaces:
1497 @internalsref{item-interface},
1498 @internalsref{self-alignment-interface},
1499 @internalsref{side-position-interface}, @internalsref{text-interface},
1500 @internalsref{text-script-interface}, @internalsref{font-interface},
1501 @internalsref{finger-interface}, and @internalsref{grob-interface}.
1504 Clicking any of the links will take you to the page of the respective
1505 object interface. Each interface has a number of properties. Some of
1506 them are not user-serviceable (@q{Internal properties}), but others
1509 We have been talking of @emph{the} @code{Fingering} object, but actually it
1510 does not amount to much. The initialization file (see
1511 @ref{Default files})
1512 @file{scm/@/define@/-grobs@/.scm} shows the soul of the @q{object},
1517 (avoid-slur . around)
1518 (slur-padding . 0.2)
1519 (staff-padding . 0.5)
1520 (self-alignment-X . 0)
1521 (self-alignment-Y . 0)
1522 (script-priority . 100)
1523 (stencil . ,ly:text-interface::print)
1524 (direction . ,ly:script-interface::calc-direction)
1525 (font-encoding . fetaNumber)
1526 (font-size . -5) ; don't overlap when next to heads.
1527 (meta . ((class . Item)
1528 (interfaces . (finger-interface
1530 text-script-interface
1532 side-position-interface
1533 self-alignment-interface
1534 item-interface))))))
1538 As you can see, the @code{Fingering} object is nothing more than a
1539 bunch of variable settings, and the webpage in the Program Reference
1540 is directly generated from this definition.
1543 @node Determining the grob property
1544 @subsection Determining the grob property
1546 Recall that we wanted to change the position of the @b{2} in
1548 @lilypond[quote,fragment,relative=2,verbatim]
1554 Since the @b{2} is vertically positioned next to its note, we have to
1555 meddle with the interface associated with this positioning. This is
1556 done using @code{side-position-interface}. The page for this interface
1560 @code{side-position-interface}
1562 Position a victim object (this one) next to other objects (the
1563 support). The property @code{direction} signifies where to put the
1564 victim object relative to the support (left or right, up or down?)
1569 Below this description, the variable @code{padding} is described as
1574 (dimension, in staff space)
1576 Add this much extra space between objects that are next to each other.
1580 By increasing the value of @code{padding}, we can move the
1581 fingering away from the notehead. The following command inserts
1582 3 staff spaces of white
1583 between the note and the fingering:
1585 \once \override Voice.Fingering #'padding = #3
1588 Inserting this command before the Fingering object is created,
1589 i.e., before @code{c2}, yields the following result:
1591 @lilypond[quote,relative=2,fragment,verbatim]
1592 \once \override Voice.Fingering #'padding = #3
1599 In this case, the context for this tweak is @context{Voice}. This
1600 fact can also be deduced from the program reference, for the page for
1601 the @internalsref{Fingering_engraver} plug-in says
1604 Fingering_engraver is part of contexts: @dots{} @internalsref{Voice}
1608 @node Objects connected to the input
1609 @subsection Objects connected to the input
1613 In some cases, it is possible to take a short-cut for tuning graphical
1614 objects. For objects that result directly from a piece of the input,
1615 you can use the @code{\tweak} function, for example
1617 @lilypond[relative=2,fragment,verbatim,ragged-right]
1620 \tweak #'color #red d
1622 \tweak #'duration-log #1 a
1623 >4-\tweak #'padding #10 -.
1626 As you can see, properties are set in the objects directly,
1627 without mentioning the grob name or context where this should be
1630 This technique only works for objects that are directly connected to
1631 an @internalsref{event} from the input, for example
1634 @item note heads, caused by chord-pitch (i.e., notes inside a chord)
1635 @item articulation signs, caused by articulation instructions
1638 It notably does not work for stems and accidentals (these are caused
1639 by note heads, not by music events) or clefs (these are not caused by
1640 music inputs, but rather by the change of a property value).
1642 There are very few objects which are @emph{directly} connected to
1643 output. A normal note (like @code{c4}) is not directly connected
1647 \tweak #'color #red c4
1651 does not change color. See @ref{Displaying music expressions}, for
1655 @node Using Scheme code instead of \tweak
1656 @subsection Using Scheme code instead of @code{\tweak}
1658 The main disadvantage of @code{\tweak} is its syntactical
1659 inflexibility. For example, the following produces a syntax error.
1662 F = \tweak #'font-size #-3 -\flageolet
1670 With other words, @code{\tweak} doesn't behave like an articulation
1671 regarding the syntax; in particular, it can't be attached with
1672 @samp{^} and @samp{_}.
1674 Using Scheme, this problem can be circumvented. The route to the
1675 result is given in @ref{Adding articulation to notes (example)},
1676 especially how to use @code{\displayMusic} as a helping guide.
1679 F = #(let ((m (make-music 'ArticulationEvent
1680 'articulation-type "flageolet")))
1681 (set! (ly:music-property m 'tweaks)
1682 (acons 'font-size -3
1683 (ly:music-property m 'tweaks)))
1692 Here, the @code{tweaks} properties of the flageolet object
1693 @samp{m} (created with @code{make-music}) are extracted with
1694 @code{ly:music-property}, a new key-value pair to change the
1695 font size is prepended to the property list with the
1696 @code{acons} Scheme function, and the result is finally
1697 written back with @code{set!}. The last element of the
1698 @code{let} block is the return value, @samp{m} itself.
1701 @node \set versus \override
1702 @subsection @code{\set} vs. @code{\override}
1704 We have seen two methods of changing properties: @code{\set} and
1705 @code{\override}. There are actually two different kinds of
1708 Contexts can have properties, which are usually named in
1709 @code{studlyCaps}. They mostly control the translation from
1710 music to notatino, eg. @code{localKeySignature} (for determining
1711 whether to print accidentals), @code{measurePosition} (for
1712 determining when to print a barline). Context properties can
1713 change value over time while interpreting a piece of music;
1714 @code{measurePosition} is an obvious example of
1715 this. Context properties are modified with @code{\set}.
1717 There is a special type of context property: the element
1718 description. These properties are named in @code{StudlyCaps}
1719 (starting with capital letters). They contain the
1720 @q{default settings} for said graphical object as an
1721 association list. See @file{scm/@/define@/-grobs@/.scm}
1722 to see what kind of settings there are. Element descriptions
1723 may be modified with @code{\override}.
1725 @code{\override} is actually a shorthand;
1728 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1732 is more or less equivalent to
1734 @c leave this long line -gp
1736 \set @var{context}.@var{name} #'@var{property} = #(cons (cons '@var{property} @var{value}) <previous value of @var{context})
1739 The value of @code{context} (the alist) is used to initalize
1740 the properties of individual grobs. Grobs also have
1741 properties, named in Scheme style, with
1742 @code{dashed-words}. The values of grob properties change
1743 during the formatting process: formatting basically amounts
1744 to computing properties using callback functions.
1746 @code{fontSize} is a special property: it is equivalent to
1747 entering @code{\override ... #'font-size} for all pertinent
1748 objects. Since this is a common change, the special
1749 property (modified with @code{\set}) was created.
1752 @node Difficult tweaks
1753 @subsection Difficult tweaks
1755 There are a few classes of difficult adjustments.
1761 One type of difficult adjustment is the appearance of spanner objects,
1762 such as slur and tie. Initially, only one of these objects is created,
1763 and they can be adjusted with the normal mechanism. However, in some
1764 cases the spanners cross line breaks. If this happens, these objects
1765 are cloned. A separate object is created for every system that it is
1766 in. These are clones of the original object and inherit all
1767 properties, including @code{\override}s.
1770 In other words, an @code{\override} always affects all pieces of a
1771 broken spanner. To change only one part of a spanner at a line break,
1772 it is necessary to hook into the formatting process. The
1773 @code{after-line-breaking} callback contains the Scheme procedure that
1774 is called after the line breaks have been determined, and layout
1775 objects have been split over different systems.
1777 In the following example, we define a procedure
1778 @code{my-callback}. This procedure
1782 determines if we have been split across line breaks
1784 if yes, retrieves all the split objects
1786 checks if we are the last of the split objects
1788 if yes, it sets @code{extra-offset}.
1791 This procedure is installed into @internalsref{Tie}, so the last part
1792 of the broken tie is translated up.
1794 @lilypond[quote,verbatim,ragged-right]
1795 #(define (my-callback grob)
1797 ; have we been split?
1798 (orig (ly:grob-original grob))
1800 ; if yes, get the split pieces (our siblings)
1801 (siblings (if (ly:grob? orig)
1802 (ly:spanner-broken-into orig) '() )))
1804 (if (and (>= (length siblings) 2)
1805 (eq? (car (last-pair siblings)) grob))
1806 (ly:grob-set-property! grob 'extra-offset '(-2 . 5)))))
1809 \override Tie #'after-line-breaking =
1816 When applying this trick, the new @code{after-line-breaking} callback
1817 should also call the old one @code{after-line-breaking}, if there is
1818 one. For example, if using this with @code{Hairpin},
1819 @code{ly:hairpin::after-line-breaking} should also be called.
1822 @item Some objects cannot be changed with @code{\override} for
1823 technical reasons. Examples of those are @code{NonMusicalPaperColumn}
1824 and @code{PaperColumn}. They can be changed with the
1825 @code{\overrideProperty} function, which works similar to @code{\once
1826 \override}, but uses a different syntax.
1830 #"Score.NonMusicalPaperColumn" % Grob name
1831 #'line-break-system-details % Property name
1832 #'((next-padding . 20)) % Value
1835 Note, however, that @code{\override}, applied to
1836 @code{NoteMusicalPaperColumn} and @code{PaperColumn}, still works as
1837 expected within @code{\context} blocks.