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)
100 @c TODO: check the context stuff below
101 @c -does it *really* work?
102 @c -the default contexts as specified in
103 @c scm/music-function.scm seem to be different -vv
105 Optionally, the function can take two arguments: the name of the
106 accidental style, and an optional argument that denotes the context that
110 #(set-accidental-style 'STYLE #('CONTEXT#))
113 If no context name is supplied, @code{Staff} is the default,
114 but you may wish to apply the accidental style to a single @code{Voice}
117 The following accidental styles are supported:
121 This is the default typesetting behavior. It corresponds
122 to 18th century common practice: Accidentals are
123 remembered to the end of the measure in which they occur and
124 only on their own octave.
126 @lilypond[quote,ragged-right]
127 musicA = { << \relative { cis'8 fis, d'4 <a cis>8 f bis4 | cis2. <c, g'>4 | } \\
128 \relative { ais'2 cis, | fis8 b a4 cis2 | } >> }
130 musicB = { \clef bass \new Voice { \voiceTwo \relative { < fis, a cis>4
131 \change Staff = up cis' \change Staff = down <fis, a>
132 \change Staff = up dis' | \change Staff = down <fis, a cis>4 gis
137 << \context Staff = "up" {
138 %#(set-accidental-style 'default)
140 \context Staff = "down"{
141 %#(set-accidental-style 'default)
143 \header { piece = \markup {\fill-line { \fontsize #3 "'default" }}}
148 The normal behavior is to remember the accidentals on
149 Staff-level. This variable, however, typesets accidentals
150 individually for each voice. Apart from that, the rule is similar to
155 #(set-accidental-style 'voice)
160 As a result, accidentals from one voice do not get canceled in other
161 voices, which is often an unwanted result: in the following example, it
162 is hard to determine whether the second @samp{a} should be played
165 @lilypond[quote,ragged-right]
166 musicA = { << \relative { cis'8 fis, d'4 <a cis>8 f bis4 | cis2. <c, g'>4 | } \\
167 \relative { ais'2 cis, | fis8 b a4 cis2 | } >> }
169 musicB = { \clef bass \new Voice { \voiceTwo \relative { < fis, a cis>4
170 \change Staff = up cis' \change Staff = down <fis, a>
171 \change Staff = up dis' | \change Staff = down <fis, a cis>4 gis
176 << \context Staff = "up" {
177 #(set-accidental-style 'voice)
179 \context Staff = "down"{
180 #(set-accidental-style 'voice)
182 \header { piece = \markup {\fill-line { \fontsize #3 "'voice" }}}
186 The @code{voice} option should be used if the voices
187 are to be read solely by individual musicians. If the staff is to be
188 used by one musician (e.g., a conductor) then
189 @code{modern} or @code{modern-cautionary}
190 should be used instead.
193 @funindex modern style accidentals
194 This rule corresponds to the common practice in the 20th century. This rule
195 prints the same accidentals as @code{default}, but temporary
196 accidentals also are canceled in other octaves. Furthermore,
197 in the same octave, they also get canceled in the following
198 measure: in the following example, notice the two natural signs which appear
199 in the second bar of the upper staff.
201 @lilypond[quote,ragged-right]
202 musicA = { << \relative { cis'8 fis, d'4 <a cis>8 f bis4 | cis2. <c, g'>4 | } \\
203 \relative { ais'2 cis, | fis8 b a4 cis2 | } >> }
205 musicB = { \clef bass \new Voice { \voiceTwo \relative { < fis, a cis>4
206 \change Staff = up cis' \change Staff = down <fis, a>
207 \change Staff = up dis' | \change Staff = down <fis, a cis>4 gis
212 << \context Staff = "up" {
213 #(set-accidental-style 'modern)
215 \context Staff = "down"{
216 #(set-accidental-style 'modern)
218 \header { piece = \markup {\fill-line { \fontsize #3 "'modern" }}}
222 @item @code{modern-cautionary}
223 @funindex modern-cautionary
224 This rule is similar to @code{modern}, but the @q{extra} accidentals
225 (the ones not typeset by @code{default}) are typeset as cautionary
226 accidentals. They are printed in reduced size or (by default)
227 with parentheses -- this can be set by definig the @code{cautionary-style}
228 property of the @internalsref{AccidentalSuggestion} object.
230 @lilypond[quote,ragged-right]
231 musicA = { << \relative { cis'8 fis, d'4 <a cis>8 f bis4 | cis2. <c, g'>4 | } \\
232 \relative { ais'2 cis, | fis8 b a4 cis2 | } >> }
234 musicB = { \clef bass \new Voice { \voiceTwo \relative { < fis, a cis>4
235 \change Staff = up cis' \change Staff = down <fis, a>
236 \change Staff = up dis' | \change Staff = down <fis, a cis>4 gis
241 << \context Staff = "up" {
242 #(set-accidental-style 'modern-cautionary)
244 \context Staff = "down"{
245 #(set-accidental-style 'modern-cautionary)
247 \header { piece = \markup {\fill-line { \fontsize #3 "'modern-cautionary" }}}
251 @funindex modern-voice
253 This rule is used for multivoice accidentals to be read both by musicians
254 playing one voice and musicians playing all voices. Accidentals are
255 typeset for each voice, but they @emph{are} canceled across voices in
256 the same @internalsref{Staff}.
258 @funindex modern-voice-cautionary
259 @item modern-voice-cautionary
260 This rule is the same as @code{modern-voice}, but with the extra
261 accidentals (the ones not typeset by @code{voice}) typeset
262 as cautionaries. Even though all accidentals typeset by
263 @code{default} @emph{are} typeset by this variable,
264 some of them are typeset as cautionaries.
267 @funindex piano accidentals
268 This rule reflects 20th century practice for piano notation. Very similar to
269 @code{modern} but accidentals also get canceled
270 across the staves in the same @internalsref{GrandStaff} or
271 @internalsref{PianoStaff}.
273 @item piano-cautionary
274 @funindex #(set-accidental-style 'piano-cautionary)
275 Same as @code{#(set-accidental-style 'piano)} but with the extra
276 accidentals typeset as cautionaries.
279 @funindex no-reset accidental style
280 This is the same as @code{default} but with accidentals lasting
281 @q{forever} and not only until the next measure
282 @lilypond[quote,ragged-right,verbatim,relative=1]
283 #(set-accidental-style 'no-reset)
288 This is sort of the opposite of @code{no-reset}: Accidentals
289 are not remembered at all -- and hence all accidentals are
290 typeset relative to the key signature, regardless of what was
293 @lilypond[quote,ragged-right,verbatim,relative=1]
294 #(set-accidental-style 'forget)
295 \key d\major c4 c cis cis d d dis dis
302 Program reference: @internalsref{Accidental_engraver},
303 @internalsref{Accidental}, @internalsref{AccidentalSuggestion} and @internalsref{AccidentalPlacement}.
308 Simultaneous notes are considered to be entered in sequential
309 mode. This means that in a chord the accidentals are typeset as if the
310 notes in the chord happen one at a time, in the order in which
311 they appear in the input file. This is a problem when accidentals
312 in a chord depend on each other,
313 which does not happen for the default accidental style. The problem
314 can be solved by manually inserting @code{!} and @code{?} for the
318 @node Setting automatic beam behavior
319 @subsection Setting automatic beam behavior
321 @funindex autoBeamSettings
322 @funindex (end * * * *)
323 @funindex (begin * * * *)
324 @cindex automatic beams, tuning
325 @cindex tuning automatic beaming
327 @c [TODO: use \applyContext]
329 In normal time signatures, automatic beams can start on any note but can
330 only end in a few positions within the measure: beams can end on a beat,
331 or at durations specified by the properties in
332 @code{autoBeamSettings}. The properties in @code{autoBeamSettings}
333 consist of a list of rules for where beams can begin and end. The
334 default @code{autoBeamSettings} rules are defined in
335 @file{scm/@/auto@/-beam@/.scm}.
337 In order to add a rule to the list, use
339 #(override-auto-beam-setting '(be p q n m) a b [context])
344 @item @code{be} is either "begin" or "end".
346 @item @code{p/q} is the duration of the note for which you want
347 to add a rule. A beam is considered to have the duration of its
348 shortest note. Set @code{p} and @code{q} to @code{'*'} to
349 have this apply to any beam.
351 @item @code{n/m} is the time signature to which
352 this rule should apply. Set @code{n} and @code{m} to @code{'*'}
353 to have this apply in any time signature.
355 @item @code{a/b} is the position in the bar at which the beam should
358 @item @code{context} is optional, and it specifies the context at which
359 the change should be made. The default is @code{'Voice}.
360 @code{#(score-override-auto-beam-setting '(A B C D) E F)} is equivalent to
361 @code{#(override-auto-beam-setting '(A B C D) E F 'Score)}.
365 For example, if automatic beams should always end on the first quarter
369 #(override-auto-beam-setting '(end * * * *) 1 4)
372 You can force the beam settings to only take effect on beams whose shortest
373 note is a certain duration
375 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
377 #(override-auto-beam-setting '(end 1 16 * *) 1 16)
379 a32 a a a a16 a a a a a |
380 #(override-auto-beam-setting '(end 1 32 * *) 1 16)
381 a32 a a a a16 a a a a a |
384 You can force the beam settings to only take effect in certain time
387 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
389 #(override-auto-beam-setting '(end * * 5 8) 2 8)
397 You can also remove a previously set beam-ending rule by using
400 #(revert-auto-beam-setting '(be p q n m) a b [context])
404 be, p, q, n, m, a, b and context are the same as above. Note that the
405 default rules are specified in @file{scm/@/auto@/-beam@/.scm},
406 so you can revert rules that you did not explicitly create.
408 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
410 a16 a a a a a a a a a a a a a a a
411 #(revert-auto-beam-setting '(end 1 16 4 4) 1 4)
412 a16 a a a a a a a a a a a a a a a
415 The rule in a revert-auto-beam-setting statement must exactly match the
416 original rule. That is, no wildcard expansion is taken into account.
418 @lilypond[quote,fragment,ragged-right,verbatim,relative=2]
420 #(override-auto-beam-setting '(end 1 16 1 4) 1 8)
422 #(revert-auto-beam-setting '(end 1 16 * *) 1 8) % this won't revert it!
424 #(revert-auto-beam-setting '(end 1 16 1 4) 1 8) % this will
430 @c TODO: old material -- not covered by above stuff, I think.
431 If automatic beams should end on every quarter in 5/4 time, specify
434 #(override-auto-beam-setting '(end * * * *) 1 4 'Staff)
435 #(override-auto-beam-setting '(end * * * *) 1 2 'Staff)
436 #(override-auto-beam-setting '(end * * * *) 3 4 'Staff)
437 #(override-auto-beam-setting '(end * * * *) 5 4 'Staff)
441 The same syntax can be used to specify beam starting points. In this
442 example, automatic beams can only end on a dotted quarter note
444 #(override-auto-beam-setting '(end * * * *) 3 8)
445 #(override-auto-beam-setting '(end * * * *) 1 2)
446 #(override-auto-beam-setting '(end * * * *) 7 8)
448 In 4/4 time signature, this means that automatic beams could end only on
449 3/8 and on the fourth beat of the measure (after 3/4, that is 2 times
450 3/8, has passed within the measure).
452 If any unexpected beam behaviour occurs, check the default automatic beam
453 settings in @file{scm/@/auto@/-beam@/.scm}
454 for possible interference, because the beam
455 endings defined there will still apply on top of your own overrides. Any
456 unwanted endings in the default vales must be reverted for your time
459 For example, to typeset @code{(3 4 3 2)}-beam endings in 12/8, begin
463 %%% revert default values in scm/auto-beam.scm regarding 12/8 time
464 #(revert-auto-beam-setting '(end * * 12 8) 3 8)
465 #(revert-auto-beam-setting '(end * * 12 8) 3 4)
466 #(revert-auto-beam-setting '(end * * 12 8) 9 8)
469 #(override-auto-beam-setting '(end 1 8 12 8) 3 8)
470 #(override-auto-beam-setting '(end 1 8 12 8) 7 8)
471 #(override-auto-beam-setting '(end 1 8 12 8) 10 8)
474 @cindex automatic beam generation
476 @funindex autoBeaming
479 If beams are used to indicate melismata in songs, then automatic
480 beaming should be switched off with @code{\autoBeamOff}.
485 @funindex \autoBeamOff
487 @funindex \autoBeamOn
492 Beaming patterns may be altered with the @code{beatGrouping} property,
494 @lilypond[quote,verbatim,relative=2,fragment,ragged-right]
496 \set beatGrouping = #'(2 3)
498 \set beatGrouping = #'(3 2)
505 If a score ends while an automatic beam has not been ended and is
506 still accepting notes, this last beam will not be typeset at all. The
507 same holds polyphonic voices, entered with @code{<< @dots{} \\ @dots{}
508 >>}. If a polyphonic voice ends while an automatic beam is still
509 accepting notes, it is not typeset.
512 @node Interpretation contexts
513 @section Interpretation contexts
515 This section describes what contexts are, and how to modify them.
518 * Contexts explained::
519 * Creating contexts::
520 * Changing context properties on the fly::
521 * Modifying context plug-ins::
522 * Layout tunings within contexts::
523 * Changing context default settings::
524 * Defining new contexts::
525 * Aligning contexts::
526 * Vertical grouping of grobs::
530 @node Contexts explained
531 @subsection Contexts explained
533 When music is printed, a lot of notational elements must be added to the
534 output. For example, compare the input and output of the following example:
536 @lilypond[quote,verbatim,relative=2,fragment]
540 The input is rather sparse, but in the output, bar lines, accidentals,
541 clef, and time signature are added. LilyPond @emph{interprets} the
542 input. During this step, the musical information is inspected in time
543 order, similar to reading a score from left to right. While reading
544 the input, the program remembers where measure boundaries are, and which
545 pitches require explicit accidentals. This information can be presented on
546 several levels. For example, the effect of an accidental is limited
547 to a single staff, while a bar line must be synchronized across the
550 Within LilyPond, these rules and bits of information are grouped in
551 @emph{Contexts}. Some examples of contexts are @context{Voice},
552 @context{Staff}, and @context{Score}. They are hierarchical, for
553 example: a @context{Staff} can contain many @context{Voice}s, and a
554 @context{Score} can contain many @context{Staff} contexts.
557 @image{context-example,5cm,,}
560 Each context has the responsibility for enforcing some notation rules,
561 creating some notation objects and maintaining the associated
562 properties. For example, the @context{Voice} context may introduce an
563 accidental and then the @context{Staff} context maintains the rule to
564 show or suppress the accidental for the remainder of the measure. The
565 synchronization of bar lines is handled at @context{Score} context.
567 However, in some music we may not want the bar lines to be
568 synchronized -- consider a polymetric score in 4/4 and 3/4 time. In
569 such cases, we must modify the default settings of the @context{Score}
570 and @context{Staff} contexts.
572 For very simple scores, contexts are created implicitly, and you need
573 not be aware of them. For larger pieces, such as anything with more
574 than one staff, they must be
575 created explicitly to make sure that you get as many staves as you
576 need, and that they are in the correct order. For typesetting pieces
577 with specialized notation, it can be useful to modify existing or
578 to define new contexts.
581 A complete description of all available contexts is in the program
584 @internalsref{Contexts}.
587 Translation @arrow{} Context.
590 @c [TODO: describe propagation]
593 @node Creating contexts
594 @subsection Creating contexts
596 For scores with only one voice and one staff, contexts are
597 created automatically. For more complex scores, it is necessary to
598 create them by hand. There are three commands that do this.
603 The easiest command is @code{\new}, and it also the quickest to type.
604 It is prepended to a music expression, for example
608 @cindex Context, creating
611 \new @var{type} @var{music expression}
615 where @var{type} is a context name (like @code{Staff} or
616 @code{Voice}). This command creates a new context, and starts
617 interpreting the @var{music expression} with that.
619 A practical application of @code{\new} is a score with many
620 staves. Each part that should be on its own staff, is preceded with
623 @lilypond[quote,verbatim,relative=2,ragged-right,fragment]
630 The @code{\new} command may also give a name to the context,
633 \new @var{type} = @var{id} @var{music}
635 However, this user specified name is only used if there is no other
636 context already earlier with the same name.
642 Like @code{\new}, the @code{\context} command also directs a music
643 expression to a context object, but gives the context an explicit name. The
647 \context @var{type} = @var{id} @var{music}
650 This form will search for an existing context of type @var{type}
651 called @var{id}. If that context does not exist yet, a new
652 context with the specified name is created. This is useful if
653 the context is referred to later on. For example, when
654 setting lyrics the melody is in a named context
657 \context Voice = "@b{tenor}" @var{music}
661 so the texts can be properly aligned to its notes,
664 \new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
669 Another possible use of named contexts is funneling two different
670 music expressions into one context. In the following example,
671 articulations and notes are entered separately,
675 arts = @{ s4-. s4-> @}
678 They are combined by sending both to the same @context{Voice} context,
682 \new Staff \context Voice = "A" \music
683 \context Voice = "A" \arts
686 @lilypond[quote,ragged-right]
690 \new Staff \context Voice = "A" \music
691 \context Voice = "A" \arts
695 With this mechanism, it is possible to define an Urtext (original
696 edition), with the option to put several distinct articulations on the
699 @cindex creating contexts
702 The third command for creating contexts is
704 \context @var{type} @var{music}
709 This is similar to @code{\context} with @code{= @var{id}}, but matches
710 any context of type @var{type}, regardless of its given name.
712 This variant is used with music expressions that can be interpreted at
713 several levels. For example, the @code{\applyOutput} command (see
714 @ref{Running a function on all layout objects}). Without an explicit
715 @code{\context}, it is usually applied to @context{Voice}
718 \applyOutput #'@var{context} #@var{function} % apply to Voice
721 To have it interpreted at the @context{Score} or @context{Staff} level use
725 \applyOutput #'Score #@var{function}
726 \applyOutput #'Staff #@var{function}
732 @node Changing context properties on the fly
733 @subsection Changing context properties on the fly
737 @cindex changing properties
739 Each context can have different @emph{properties}, variables contained
740 in that context. They can be changed during the interpretation step.
741 This is achieved by inserting the @code{\set} command in the music,
744 \set @var{context}.@var{prop} = #@var{value}
748 @lilypond[quote,verbatim,relative=2,fragment]
750 \set Score.skipBars = ##t
754 This command skips measures that have no notes. The result is that
755 multi-rests are condensed. The value assigned is a Scheme object. In
756 this case, it is @code{#t}, the boolean True value.
758 If the @var{context} argument is left out, then the current bottom-most
759 context (typically @context{ChordNames}, @context{Voice}, or
760 @context{Lyrics}) is used. In this example,
762 @lilypond[quote,verbatim,relative=2,fragment]
764 \set autoBeaming = ##f
769 the @var{context} argument to @code{\set} is left out, so automatic
770 beaming is switched off in the current @internalsref{Voice}. Note that
771 the bottom-most context does not always contain the property that you
772 wish to change -- for example, attempting to set the @code{skipBars}
773 property (of the bottom-most context, in this case @code{Voice}) will
776 @lilypond[quote,verbatim,relative=2,fragment]
782 Contexts are hierarchical, so if a bigger context was specified, for
783 example @context{Staff}, then the change would also apply to all
784 @context{Voice}s in the current stave. The change is applied
785 @q{on-the-fly}, during the music, so that the setting only affects the
786 second group of eighth notes.
790 There is also an @code{\unset} command,
792 \unset @var{context}.@var{prop}
796 which removes the definition of @var{prop}. This command removes
797 the definition only if it is set in @var{context}, so
800 \set Staff.autoBeaming = ##f
804 introduces a property setting at @code{Staff} level. The setting also
805 applies to the current @code{Voice}. However,
808 \unset Voice.autoBeaming
812 does not have any effect. To cancel this setting, the @code{\unset}
813 must be specified on the same level as the original @code{\set}. In
814 other words, undoing the effect of @code{Staff.autoBeaming = ##f}
817 \unset Staff.autoBeaming
820 Like @code{\set}, the @var{context} argument does not have to be
821 specified for a bottom context, so the two statements
824 \set Voice.autoBeaming = ##t
825 \set autoBeaming = ##t
833 Settings that should only apply to a single time-step can be entered
834 with @code{\once}, for example in
836 @lilypond[quote,verbatim,relative=2,fragment]
838 \once \set fontSize = #4.7
843 the property @code{fontSize} is unset automatically after the second
846 A full description of all available context properties is in the
847 program reference, see
849 @internalsref{Tunable context properties}.
852 Translation @arrow{} Tunable context properties.
856 @node Modifying context plug-ins
857 @subsection Modifying context plug-ins
859 Notation contexts (like @code{Score} and @code{Staff}) not only
861 they also contain plug-ins called @q{engravers} that create notation
862 elements. For example, the @code{Voice} context contains a
863 @code{Note_head_engraver} and the @code{Staff} context contains a
864 @code{Key_signature_engraver}.
866 For a full a description of each plug-in, see
868 @internalsref{Engravers}.
871 Program reference @arrow Translation @arrow{} Engravers.
873 Every context described in
875 @internalsref{Contexts}
878 Program reference @arrow Translation @arrow{} Context.
880 lists the engravers used for that context.
883 It can be useful to shuffle around these plug-ins. This is done by
884 starting a new context with @code{\new} or @code{\context}, and
890 \new @var{context} \with @{
903 where the @dots{} should be the name of an engraver. Here is a simple
904 example which removes @code{Time_signature_engraver} and
905 @code{Clef_engraver} from a @code{Staff} context,
907 @lilypond[quote,relative=1,verbatim,fragment]
913 \remove "Time_signature_engraver"
914 \remove "Clef_engraver"
921 In the second staff there are no time signature or clef symbols. This
922 is a rather crude method of making objects disappear since it will affect
923 the entire staff. This method also influences the spacing, which may or
924 may not be desirable. A more
925 sophisticated method of blanking objects is shown in @ref{Common tweaks}.
927 The next example shows a practical application. Bar lines and time
928 signatures are normally synchronized across the score. This is done
929 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
930 This plug-in keeps an administration of time signature, location
931 within the measure, etc. By moving thes engraver from @code{Score} to
932 @code{Staff} context, we can have a score where each staff has its own
935 @cindex polymetric scores
936 @cindex Time signatures, multiple
938 @lilypond[quote,relative=1,ragged-right,verbatim,fragment]
940 \remove "Timing_translator"
941 \remove "Default_bar_line_engraver"
944 \consists "Timing_translator"
945 \consists "Default_bar_line_engraver"
951 \consists "Timing_translator"
952 \consists "Default_bar_line_engraver"
961 @node Layout tunings within contexts
962 @subsection Layout tunings within contexts
964 Each context is responsible for creating certain types of graphical
965 objects. The settings used for printing these objects are also stored by
966 context. By changing these settings, the appearance of objects can be
969 The syntax for this is
972 \override @var{context}.@var{name} #'@var{property} = #@var{value}
975 Here @var{name} is the name of a graphical object, like @code{Stem} or
976 @code{NoteHead}, and @var{property} is an internal variable of the
977 formatting system (@q{grob property} or @q{layout property}). The latter is a
978 symbol, so it must be quoted. The subsection @ref{Constructing a
979 tweak}, explains what to fill in for @var{name}, @var{property}, and
980 @var{value}. Here we only discuss the functionality of this command.
985 \override Staff.Stem #'thickness = #4.0
989 makes stems thicker (the default is 1.3, with staff line thickness as a
990 unit). Since the command specifies @context{Staff} as context, it only
991 applies to the current staff. Other staves will keep their normal
992 appearance. Here we see the command in action:
994 @lilypond[quote,verbatim,relative=2,fragment]
996 \override Staff.Stem #'thickness = #4.0
1002 The @code{\override} command changes the definition of the @code{Stem}
1003 within the current @context{Staff}. After the command is interpreted
1004 all stems are thickened.
1006 Analogous to @code{\set}, the @var{context} argument may be left out,
1007 causing the default context @context{Voice} to be used. Adding
1008 @code{\once} applies the change during one timestep only.
1010 @lilypond[quote,fragment,verbatim,relative=2]
1012 \once \override Stem #'thickness = #4.0
1017 The @code{\override} must be done before the object is
1018 started. Therefore, when altering @emph{Spanner} objects such as slurs
1019 or beams, the @code{\override} command must be executed at the moment
1020 when the object is created. In this example,
1022 @lilypond[quote,fragment,verbatim,relative=2]
1023 \override Slur #'thickness = #3.0
1025 \override Beam #'thickness = #0.6
1030 the slur is fatter but the beam is not. This is because the command for
1031 @code{Beam} comes after the Beam is started, so it has no effect.
1033 Analogous to @code{\unset}, the @code{\revert} command for a context
1034 undoes an @code{\override} command; like with @code{\unset}, it only
1035 affects settings that were made in the same context. In other words, the
1036 @code{\revert} in the next example does not do anything.
1039 \override Voice.Stem #'thickness = #4.0
1040 \revert Staff.Stem #'thickness
1043 Some tweakable options are called @q{subproperties} and reside inside
1044 properties. To tweak those, use commands of the form
1046 @c leave this as a long long
1048 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
1055 \override Stem #'details #'beamed-lengths = #'(4 4 3)
1061 Internals: @internalsref{OverrideProperty}, @internalsref{RevertProperty},
1062 @internalsref{PropertySet}, @internalsref{Backend}, and
1063 @internalsref{All layout objects}.
1068 The back-end is not very strict in type-checking object properties.
1069 Cyclic references in Scheme values for properties can cause hangs
1070 or crashes, or both.
1073 @node Changing context default settings
1074 @subsection Changing context default settings
1076 The adjustments of the previous subsections (@ref{Changing context
1077 properties on the fly}, @ref{Modifying context plug-ins}, and
1078 @ref{Layout tunings within contexts}) can also be entered separately
1079 from the music in the @code{\layout} block,
1088 \override Stem #'thickness = #4.0
1089 \remove "Time_signature_engraver"
1094 The @code{\Staff} command brings in the existing definition of the
1095 staff context so that it can be modified.
1100 \override Stem #'thickness = #4.0
1101 \remove "Time_signature_engraver"
1105 affect all staves in the score. Other contexts can be modified
1108 The @code{\set} keyword is optional within the @code{\layout} block, so
1124 It is not possible to collect context changes in a variable and apply
1125 them to a @code{\context} definition by referring to that variable.
1127 The @code{\RemoveEmptyStaffContext} will overwrite your current
1128 @code{\Staff} settings. If you wish to change the defaults for a
1129 staff which uses @code{\RemoveEmptyStaffContext}, you must do so
1130 after calling @code{\RemoveemptyStaffContext}, ie
1135 \RemoveEmptyStaffContext
1137 \override Stem #'thickness = #4.0
1143 @node Defining new contexts
1144 @subsection Defining new contexts
1146 Specific contexts, like @context{Staff} and @code{Voice}, are made of
1147 simple building blocks. It is possible to create new types of
1148 contexts with different combinations of engraver plug-ins.
1150 The next example shows how to build a different type of
1151 @context{Voice} context from scratch. It will be similar to
1152 @code{Voice}, but only prints centered slash noteheads. It can be used
1153 to indicate improvisation in jazz pieces,
1155 @lilypond[quote,ragged-right]
1156 \layout { \context {
1158 \type "Engraver_group"
1159 \consists "Note_heads_engraver"
1160 \consists "Text_engraver"
1161 \consists Pitch_squash_engraver
1162 squashedPosition = #0
1163 \override NoteHead #'style = #'slash
1164 \override Stem #'transparent = ##t
1168 \accepts "ImproVoice"
1172 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1173 c4 c^"undress" c_"while playing :)" c }
1179 These settings are defined within a @code{\context} block inside a
1180 @code{\layout} block,
1190 In the following discussion, the example input shown should go in place
1191 of the @dots{} in the previous fragment.
1193 First it is necessary to define a name for the new context:
1199 Since it is similar to the @context{Voice}, we want commands that work
1200 on (existing) @context{Voice}s to remain working. This is achieved by
1201 giving the new context an alias @context{Voice},
1207 The context will print notes and instructive texts, so we need to add
1208 the engravers which provide this functionality,
1211 \consists Note_heads_engraver
1212 \consists Text_engraver
1215 but we only need this on the center line,
1218 \consists Pitch_squash_engraver
1219 squashedPosition = #0
1222 The @internalsref{Pitch_squash_engraver} modifies note heads (created
1223 by @internalsref{Note_heads_engraver}) and sets their vertical
1224 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
1227 The notes look like a slash, and have no stem,
1230 \override NoteHead #'style = #'slash
1231 \override Stem #'transparent = ##t
1234 All these plug-ins have to cooperate, and this is achieved with a
1235 special plug-in, which must be marked with the keyword @code{\type}.
1236 This should always be @internalsref{Engraver_group},
1239 \type "Engraver_group"
1242 Put together, we get
1247 \type "Engraver_group"
1248 \consists "Note_heads_engraver"
1249 \consists "Text_engraver"
1250 \consists Pitch_squash_engraver
1251 squashedPosition = #0
1252 \override NoteHead #'style = #'slash
1253 \override Stem #'transparent = ##t
1259 Contexts form hierarchies. We want to hang the @context{ImproVoice}
1260 under @context{Staff}, just like normal @code{Voice}s. Therefore, we
1261 modify the @code{Staff} definition with the @code{\accepts}
1272 The opposite of @code{\accepts} is @code{\denies},
1273 which is sometimes needed when reusing existing context definitions.
1275 Putting both into a @code{\layout} block, like
1285 \accepts "ImproVoice"
1290 Then the output at the start of this subsection can be entered as
1298 c c_"while playing :)"
1305 @node Aligning contexts
1306 @subsection Aligning contexts
1308 New contexts may be aligned above or below exisiting contexts. This
1309 could be useful in setting up a vocal staff (@ref{Vocal ensembles}) and
1313 @findex alignAboveContext
1314 @findex alignBelowContext
1316 @lilypond[quote,ragged-right]
1317 ossia = { f4 f f f }
1319 \relative c' \new Staff = "main" {
1322 \new Staff \with {alignAboveContext=main} \ossia
1323 { d8 f d f d f d f }
1330 @node Vertical grouping of grobs
1331 @subsection Vertical grouping of grobs
1333 The VerticalAlignment and VerticalAxisGroup grobs work together.
1334 VerticalAxisGroup groups together different grobs like Staff, Lyrics,
1335 etc. VerticalAlignment then vertically aligns the different grobs
1336 grouped together by VerticalAxisGroup. There is usually only one
1337 VerticalAlignment per score but every Staff, Lyrics, etc. has its own
1341 @node The \override command
1342 @section The @code{\override} command
1344 In the previous section, we have already touched on a command that
1345 changes layout details: the @code{\override} command. In this section,
1346 we will look in more detail at how to use the command in practice. The
1347 general syntax of this command is:
1350 \override @var{context}.@var{layout_object} #'@var{layout_property} = #@var{value}
1353 This will set the @var{layout_property} of the specified @var{layout_object},
1354 which is a member of the @var{context}, to the @var{value}.
1357 * Constructing a tweak::
1358 * Navigating the program reference::
1359 * Layout interfaces::
1360 * Determining the grob property::
1361 * Objects connected to the input::
1362 * Using Scheme code instead of \tweak::
1363 * \set versus \override::
1364 * Difficult tweaks::
1369 @node Constructing a tweak
1370 @subsection Constructing a tweak
1372 Commands which change output generally look like
1375 \override Voice.Stem #'thickness = #3.0
1379 To construct this tweak we must determine these bits of information:
1382 @item the context: here @context{Voice}.
1383 @item the layout object: here @code{Stem}.
1384 @item the layout property: here @code{thickness}.
1385 @item a sensible value: here @code{3.0}.
1388 Some tweakable options are called @q{subproperties} and reside inside
1389 properties. To tweak those, use commands in the form
1392 \override Stem #'details #'beamed-lengths = #'(4 4 3)
1395 @cindex internal documentation
1396 @cindex finding graphical objects
1397 @cindex graphical object descriptions
1400 @cindex internal documentation
1402 For many properties, regardless of the data type of the property, setting the
1403 property to false ( @code{##f} ) will result in turning it off, causing
1404 Lilypond to ignore that property entirely. This is particularly useful for
1405 turning off grob properties which may otherwise be causing problems.
1407 We demonstrate how to glean this information from the notation manual
1408 and the program reference.
1413 @node Navigating the program reference
1414 @subsection Navigating the program reference
1416 Suppose we want to move the fingering indication in the fragment
1419 @lilypond[quote,fragment,relative=2,verbatim]
1425 If you visit the documentation on fingering instructions (in
1426 @ref{Fingering instructions}), you will notice:
1431 Program reference: @internalsref{Fingering}.
1436 @c outdated info; probably will delete.
1438 This fragment points to two parts of the program reference: a page
1439 on @code{FingerEvent} and one on @code{Fingering}.
1441 The page on @code{FingerEvent} describes the properties of the music
1442 expression for the input @code{-2}. The page contains many links
1443 forward. For example, it says
1446 Accepted by: @internalsref{Fingering_engraver},
1450 That link brings us to the documentation for the Engraver, the
1454 This engraver creates the following layout objects: @internalsref{Fingering}.
1457 In other words, once the @code{FingerEvent}s are interpreted, the
1458 @code{Fingering_engraver} plug-in will process them.
1462 @c I can't figure out what this is supposed to mean. -gp
1464 The @code{Fingering_engraver} is also listed to create
1465 @internalsref{Fingering} objects,
1467 @c old info? it doesn't make any sense to me with our current docs.
1469 second bit of information listed under @b{See also} in the Notation
1474 The programmer's reference is available as an HTML document. It is
1475 highly recommended that you read it in HTML form, either online or
1476 by downloading the HTML documentation. This section will be much more
1477 difficult to understand if you are using the
1481 Follow the link to @internalsref{Fingering}. At the top of the
1485 Fingering objects are created by: @internalsref{Fingering_engraver} and
1486 @internalsref{New_fingering_engraver}.
1489 By following related links inside the program reference, we can follow the
1490 flow of information within the program:
1494 @item @internalsref{Fingering}:
1495 @internalsref{Fingering} objects are created by:
1496 @internalsref{Fingering_engraver}
1498 @item @internalsref{Fingering_engraver}:
1499 Music types accepted: @internalsref{fingering-event}
1501 @item @internalsref{fingering-event}:
1502 Music event type @code{fingering-event} is in Music expressions named
1503 @internalsref{FingerEvent}
1506 This path goes against the flow of information in the program: it
1507 starts from the output, and ends at the input event. You could
1508 also start at an input event, and read with the flow of
1509 information, eventually ending up at the output object(s).
1511 The program reference can also be browsed like a normal document. It
1512 contains chapters on
1514 @internalsref{Music definitions},
1517 @code{Music definitions}
1519 on @internalsref{Translation}, and the @internalsref{Backend}. Every
1520 chapter lists all the definitions used and all properties that may be
1524 @node Layout interfaces
1525 @subsection Layout interfaces
1527 @cindex interface, layout
1528 @cindex layout interface
1531 The HTML page that we found in the previous section describes the
1532 layout object called @internalsref{Fingering}. Such an object is a
1533 symbol within the score. It has properties that store numbers (like
1534 thicknesses and directions), but also pointers to related objects. A
1535 layout object is also called a @emph{Grob}, which is short for Graphical
1536 Object. For more details about Grobs, see @internalsref{grob-interface}.
1538 The page for @code{Fingering} lists the definitions for the
1539 @code{Fingering} object. For example, the page says
1542 @code{padding} (dimension, in staff space):
1548 which means that the number will be kept at a distance of at least 0.5
1552 Each layout object may have several functions as a notational or
1553 typographical element. For example, the Fingering object
1554 has the following aspects
1558 Its size is independent of the horizontal spacing, unlike slurs or beams.
1561 It is a piece of text. Granted, it is usually a very short text.
1564 That piece of text is typeset with a font, unlike slurs or beams.
1567 Horizontally, the center of the symbol should be aligned to the
1568 center of the notehead.
1571 Vertically, the symbol is placed next to the note and the staff.
1574 The vertical position is also coordinated with other superscript
1575 and subscript symbols.
1578 Each of these aspects is captured in so-called @emph{interface}s,
1579 which are listed on the @internalsref{Fingering} page at the bottom
1582 This object supports the following interfaces:
1583 @internalsref{item-interface},
1584 @internalsref{self-alignment-interface},
1585 @internalsref{side-position-interface}, @internalsref{text-interface},
1586 @internalsref{text-script-interface}, @internalsref{font-interface},
1587 @internalsref{finger-interface}, and @internalsref{grob-interface}.
1590 Clicking any of the links will take you to the page of the respective
1591 object interface. Each interface has a number of properties. Some of
1592 them are not user-serviceable (@q{Internal properties}), but others
1595 We have been talking of @emph{the} @code{Fingering} object, but actually it
1596 does not amount to much. The initialization file (see
1597 @ref{Default files})
1598 @file{scm/@/define@/-grobs@/.scm} shows the soul of the @q{object},
1603 (avoid-slur . around)
1604 (slur-padding . 0.2)
1605 (staff-padding . 0.5)
1606 (self-alignment-X . 0)
1607 (self-alignment-Y . 0)
1608 (script-priority . 100)
1609 (stencil . ,ly:text-interface::print)
1610 (direction . ,ly:script-interface::calc-direction)
1611 (font-encoding . fetaNumber)
1612 (font-size . -5) ; don't overlap when next to heads.
1613 (meta . ((class . Item)
1614 (interfaces . (finger-interface
1616 text-script-interface
1618 side-position-interface
1619 self-alignment-interface
1620 item-interface))))))
1624 As you can see, the @code{Fingering} object is nothing more than a
1625 bunch of variable settings, and the webpage in the Program Reference
1626 is directly generated from this definition.
1629 @node Determining the grob property
1630 @subsection Determining the grob property
1632 Recall that we wanted to change the position of the @b{2} in
1634 @lilypond[quote,fragment,relative=2,verbatim]
1640 Since the @b{2} is vertically positioned next to its note, we have to
1641 meddle with the interface associated with this positioning. This is
1642 done using @code{side-position-interface}. The page for this interface
1646 @code{side-position-interface}
1648 Position a victim object (this one) next to other objects (the
1649 support). The property @code{direction} signifies where to put the
1650 victim object relative to the support (left or right, up or down?)
1655 Below this description, the variable @code{padding} is described as
1660 (dimension, in staff space)
1662 Add this much extra space between objects that are next to each other.
1666 By increasing the value of @code{padding}, we can move the
1667 fingering away from the notehead. The following command inserts
1668 3 staff spaces of white
1669 between the note and the fingering:
1671 \once \override Voice.Fingering #'padding = #3
1674 Inserting this command before the Fingering object is created,
1675 i.e., before @code{c2}, yields the following result:
1677 @lilypond[quote,relative=2,fragment,verbatim]
1678 \once \override Voice.Fingering #'padding = #3
1685 In this case, the context for this tweak is @context{Voice}. This
1686 fact can also be deduced from the program reference, for the page for
1687 the @internalsref{Fingering_engraver} plug-in says
1690 Fingering_engraver is part of contexts: @dots{} @internalsref{Voice}
1694 @node Objects connected to the input
1695 @subsection Objects connected to the input
1699 In some cases, it is possible to take a short-cut for tuning graphical
1700 objects. For objects that result directly from a piece of the input,
1701 you can use the @code{\tweak} function, for example
1703 @lilypond[relative=2,fragment,verbatim,ragged-right]
1706 \tweak #'color #red d
1708 \tweak #'duration-log #1 a
1709 >4-\tweak #'padding #10 -.
1712 As you can see, properties are set in the objects directly,
1713 without mentioning the grob name or context where this should be
1716 This technique only works for objects that are directly connected to
1717 an @internalsref{event} from the input, for example
1720 @item note heads, caused by chord-pitch (i.e., notes inside a chord)
1721 @item articulation signs, caused by articulation instructions
1724 It notably does not work for stems and accidentals (these are caused
1725 by note heads, not by music events) or clefs (these are not caused by
1726 music inputs, but rather by the change of a property value).
1728 There are very few objects which are @emph{directly} connected to
1729 output. A normal note (like @code{c4}) is not directly connected
1733 \tweak #'color #red c4
1737 does not change color. See @ref{Displaying music expressions}, for
1741 @node Using Scheme code instead of \tweak
1742 @subsection Using Scheme code instead of @code{\tweak}
1744 The main disadvantage of @code{\tweak} is its syntactical
1745 inflexibility. For example, the following produces a syntax error.
1748 F = \tweak #'font-size #-3 -\flageolet
1756 With other words, @code{\tweak} doesn't behave like an articulation
1757 regarding the syntax; in particular, it can't be attached with
1758 @samp{^} and @samp{_}.
1760 Using Scheme, this problem can be circumvented. The route to the
1761 result is given in @ref{Adding articulation to notes (example)},
1762 especially how to use @code{\displayMusic} as a helping guide.
1765 F = #(let ((m (make-music 'ArticulationEvent
1766 'articulation-type "flageolet")))
1767 (set! (ly:music-property m 'tweaks)
1768 (acons 'font-size -3
1769 (ly:music-property m 'tweaks)))
1778 Here, the @code{tweaks} properties of the flageolet object
1779 @samp{m} (created with @code{make-music}) are extracted with
1780 @code{ly:music-property}, a new key-value pair to change the
1781 font size is prepended to the property list with the
1782 @code{acons} Scheme function, and the result is finally
1783 written back with @code{set!}. The last element of the
1784 @code{let} block is the return value, @samp{m} itself.
1787 @node \set versus \override
1788 @subsection @code{\set} vs. @code{\override}
1790 We have seen two methods of changing properties: @code{\set} and
1791 @code{\override}. There are actually two different kinds of
1794 Contexts can have properties, which are usually named in
1795 @code{studlyCaps}. They mostly control the translation from
1796 music to notatino, eg. @code{localKeySignature} (for determining
1797 whether to print accidentals), @code{measurePosition} (for
1798 determining when to print a barline). Context properties can
1799 change value over time while interpreting a piece of music;
1800 @code{measurePosition} is an obvious example of
1801 this. Context properties are modified with @code{\set}.
1803 There is a special type of context property: the element
1804 description. These properties are named in @code{StudlyCaps}
1805 (starting with capital letters). They contain the
1806 @q{default settings} for said graphical object as an
1807 association list. See @file{scm/@/define@/-grobs@/.scm}
1808 to see what kind of settings there are. Element descriptions
1809 may be modified with @code{\override}.
1811 @code{\override} is actually a shorthand;
1814 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1818 is more or less equivalent to
1820 @c leave this long line -gp
1822 \set @var{context}.@var{name} #'@var{property} = #(cons (cons '@var{property} @var{value}) <previous value of @var{context})
1825 The value of @code{context} (the alist) is used to initalize
1826 the properties of individual grobs. Grobs also have
1827 properties, named in Scheme style, with
1828 @code{dashed-words}. The values of grob properties change
1829 during the formatting process: formatting basically amounts
1830 to computing properties using callback functions.
1832 @code{fontSize} is a special property: it is equivalent to
1833 entering @code{\override ... #'font-size} for all pertinent
1834 objects. Since this is a common change, the special
1835 property (modified with @code{\set}) was created.
1838 @node Difficult tweaks
1839 @subsection Difficult tweaks
1841 There are a few classes of difficult adjustments.
1847 One type of difficult adjustment is the appearance of spanner objects,
1848 such as slur and tie. Initially, only one of these objects is created,
1849 and they can be adjusted with the normal mechanism. However, in some
1850 cases the spanners cross line breaks. If this happens, these objects
1851 are cloned. A separate object is created for every system that it is
1852 in. These are clones of the original object and inherit all
1853 properties, including @code{\override}s.
1856 In other words, an @code{\override} always affects all pieces of a
1857 broken spanner. To change only one part of a spanner at a line break,
1858 it is necessary to hook into the formatting process. The
1859 @code{after-line-breaking} callback contains the Scheme procedure that
1860 is called after the line breaks have been determined, and layout
1861 objects have been split over different systems.
1863 In the following example, we define a procedure
1864 @code{my-callback}. This procedure
1868 determines if we have been split across line breaks
1870 if yes, retrieves all the split objects
1872 checks if we are the last of the split objects
1874 if yes, it sets @code{extra-offset}.
1877 This procedure is installed into @internalsref{Tie}, so the last part
1878 of the broken tie is translated up.
1880 @lilypond[quote,verbatim,ragged-right]
1881 #(define (my-callback grob)
1883 ; have we been split?
1884 (orig (ly:grob-original grob))
1886 ; if yes, get the split pieces (our siblings)
1887 (siblings (if (ly:grob? orig)
1888 (ly:spanner-broken-into orig) '() )))
1890 (if (and (>= (length siblings) 2)
1891 (eq? (car (last-pair siblings)) grob))
1892 (ly:grob-set-property! grob 'extra-offset '(-2 . 5)))))
1895 \override Tie #'after-line-breaking =
1902 When applying this trick, the new @code{after-line-breaking} callback
1903 should also call the old one @code{after-line-breaking}, if there is
1904 one. For example, if using this with @code{Hairpin},
1905 @code{ly:hairpin::after-line-breaking} should also be called.
1908 @item Some objects cannot be changed with @code{\override} for
1909 technical reasons. Examples of those are @code{NonMusicalPaperColumn}
1910 and @code{PaperColumn}. They can be changed with the
1911 @code{\overrideProperty} function, which works similar to @code{\once
1912 \override}, but uses a different syntax.
1916 #"Score.NonMusicalPaperColumn" % Grob name
1917 #'line-break-system-details % Property name
1918 #'((next-padding . 20)) % Value
1921 Note, however, that @code{\override}, applied to
1922 @code{NoteMusicalPaperColumn} and @code{PaperColumn}, still works as
1923 expected within @code{\context} blocks.