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::
443 @node Contexts explained
444 @subsection Contexts explained
446 When music is printed, a lot of notational elements must be added to the
447 input. For example, compare the input and output of the following example:
449 @lilypond[quote,verbatim,relative=2,fragment]
453 The input is rather sparse, but in the output, bar lines, accidentals,
454 clef, and time signature are added. LilyPond @emph{interprets} the
455 input. During this step, the musical information is inspected in time
456 order, similar to reading a score from left to right. While reading
457 the input, the program remembers where measure boundaries are, and which
458 pitches require explicit accidentals. This information can be presented on
459 several levels. For example, the effect of an accidental is limited
460 to a single staff, while a bar line must be synchronized across the
463 Within LilyPond, these rules and bits of information are grouped in
464 @emph{Contexts}. Some examples of contexts are @context{Voice},
465 @context{Staff}, and @context{Score}. They are hierarchical, for
466 example: a @context{Staff} can contain many @context{Voice}s, and a
467 @context{Score} can contain many @context{Staff} contexts.
470 @image{context-example,5cm,,}
473 Each context has the responsibility for enforcing some notation rules,
474 creating some notation objects and maintaining the associated
475 properties. For example, the @context{Voice} context may introduce an
476 accidental and then the @context{Staff} context maintains the rule to
477 show or suppress the accidental for the remainder of the measure. The
478 synchronization of bar lines is handled at @context{Score} context.
480 However, in some music we may not want the bar lines to be
481 synchronized -- consider a polymetric score in 4/4 and 3/4 time. In
482 such cases, we must modify the default settings of the @context{Score}
483 and @context{Staff} contexts.
485 For very simple scores, contexts are created implicitly, and you need
486 not be aware of them. For larger pieces, such as anything with more
487 than one staff, they must be
488 created explicitly to make sure that you get as many staves as you
489 need, and that they are in the correct order. For typesetting pieces
490 with specialized notation, it can be useful to modify existing or
491 to define new contexts.
494 A complete description of all available contexts is in the program
497 @internalsref{Contexts}.
500 Translation @arrow{} Context.
503 @c [TODO: describe propagation]
506 @node Creating contexts
507 @subsection Creating contexts
509 For scores with only one voice and one staff, contexts are
510 created automatically. For more complex scores, it is necessary to
511 create them by hand. There are three commands that do this.
516 The easiest command is @code{\new}, and it also the quickest to type.
517 It is prepended to a music expression, for example
521 @cindex Context, creating
524 \new @var{type} @var{music expression}
528 where @var{type} is a context name (like @code{Staff} or
529 @code{Voice}). This command creates a new context, and starts
530 interpreting the @var{music expression} with that.
532 A practical application of @code{\new} is a score with many
533 staves. Each part that should be on its own staff, is preceded with
536 @lilypond[quote,verbatim,relative=2,ragged-right,fragment]
543 The @code{\new} command may also give a name to the context,
546 \new @var{type} = @var{id} @var{music}
548 However, this user specified name is only used if there is no other
549 context already earlier with the same name.
555 Like @code{\new}, the @code{\context} command also directs a music
556 expression to a context object, but gives the context an explicit name. The
560 \context @var{type} = @var{id} @var{music}
563 This form will search for an existing context of type @var{type}
564 called @var{id}. If that context does not exist yet, a new
565 context with the specified name is created. This is useful if
566 the context is referred to later on. For example, when
567 setting lyrics the melody is in a named context
570 \context Voice = "@b{tenor}" @var{music}
574 so the texts can be properly aligned to its notes,
577 \new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
582 Another possible use of named contexts is funneling two different
583 music expressions into one context. In the following example,
584 articulations and notes are entered separately,
588 arts = @{ s4-. s4-> @}
591 They are combined by sending both to the same @context{Voice} context,
595 \new Staff \context Voice = "A" \music
596 \context Voice = "A" \arts
599 @lilypond[quote,ragged-right]
603 \new Staff \context Voice = "A" \music
604 \context Voice = "A" \arts
608 With this mechanism, it is possible to define an Urtext (original
609 edition), with the option to put several distinct articulations on the
612 @cindex creating contexts
615 The third command for creating contexts is
617 \context @var{type} @var{music}
622 This is similar to @code{\context} with @code{= @var{id}}, but matches
623 any context of type @var{type}, regardless of its given name.
625 This variant is used with music expressions that can be interpreted at
626 several levels. For example, the @code{\applyOutput} command (see
627 @ref{Running a function on all layout objects}). Without an explicit
628 @code{\context}, it is usually applied to @context{Voice}
631 \applyOutput #'@var{context} #@var{function} % apply to Voice
634 To have it interpreted at the @context{Score} or @context{Staff} level use
638 \applyOutput #'Score #@var{function}
639 \applyOutput #'Staff #@var{function}
645 @node Changing context properties on the fly
646 @subsection Changing context properties on the fly
650 @cindex changing properties
652 Each context can have different @emph{properties}, variables contained
653 in that context. They can be changed during the interpretation step.
654 This is achieved by inserting the @code{\set} command in the music,
657 \set @var{context}.@var{prop} = #@var{value}
661 @lilypond[quote,verbatim,relative=2,fragment]
663 \set Score.skipBars = ##t
667 This command skips measures that have no notes. The result is that
668 multi-rests are condensed. The value assigned is a Scheme object. In
669 this case, it is @code{#t}, the boolean True value.
671 If the @var{context} argument is left out, then the current bottom-most
672 context (typically @context{ChordNames}, @context{Voice}, or
673 @context{Lyrics}) is used. In this example,
675 @lilypond[quote,verbatim,relative=2,fragment]
677 \set autoBeaming = ##f
682 the @var{context} argument to @code{\set} is left out, so automatic
683 beaming is switched off in the current @internalsref{Voice}. Note that
684 the bottom-most context does not always contain the property that you
685 wish to change -- for example, attempting to set the @code{skipBars}
686 property (of the bottom-most context, in this case @code{Voice}) will
689 @lilypond[quote,verbatim,relative=2,fragment]
695 Contexts are hierarchical, so if a bigger context was specified, for
696 example @context{Staff}, then the change would also apply to all
697 @context{Voice}s in the current stave. The change is applied
698 @q{on-the-fly}, during the music, so that the setting only affects the
699 second group of eighth notes.
703 There is also an @code{\unset} command,
705 \unset @var{context}.@var{prop}
709 which removes the definition of @var{prop}. This command removes
710 the definition only if it is set in @var{context}, so
713 \set Staff.autoBeaming = ##f
717 introduces a property setting at @code{Staff} level. The setting also
718 applies to the current @code{Voice}. However,
721 \unset Voice.autoBeaming
725 does not have any effect. To cancel this setting, the @code{\unset}
726 must be specified on the same level as the original @code{\set}. In
727 other words, undoing the effect of @code{Staff.autoBeaming = ##f}
730 \unset Staff.autoBeaming
733 Like @code{\set}, the @var{context} argument does not have to be
734 specified for a bottom context, so the two statements
737 \set Voice.autoBeaming = ##t
738 \set autoBeaming = ##t
746 Settings that should only apply to a single time-step can be entered
747 with @code{\once}, for example in
749 @lilypond[quote,verbatim,relative=2,fragment]
751 \once \set fontSize = #4.7
756 the property @code{fontSize} is unset automatically after the second
759 A full description of all available context properties is in the
760 program reference, see
762 @internalsref{Tunable context properties}.
765 Translation @arrow{} Tunable context properties.
769 @node Modifying context plug-ins
770 @subsection Modifying context plug-ins
772 Notation contexts (like @code{Score} and @code{Staff}) not only
774 they also contain plug-ins called @q{engravers} that create notation
775 elements. For example, the @code{Voice} context contains a
776 @code{Note_head_engraver} and the @code{Staff} context contains a
777 @code{Key_signature_engraver}.
779 For a full a description of each plug-in, see
781 @internalsref{Engravers}.
784 Program reference @arrow Translation @arrow{} Engravers.
786 Every context described in
788 @internalsref{Contexts}
791 Program reference @arrow Translation @arrow{} Context.
793 lists the engravers used for that context.
796 It can be useful to shuffle around these plug-ins. This is done by
797 starting a new context with @code{\new} or @code{\context}, and
803 \new @var{context} \with @{
816 where the @dots{} should be the name of an engraver. Here is a simple
817 example which removes @code{Time_signature_engraver} and
818 @code{Clef_engraver} from a @code{Staff} context,
820 @lilypond[quote,relative=1,verbatim,fragment]
826 \remove "Time_signature_engraver"
827 \remove "Clef_engraver"
834 In the second staff there are no time signature or clef symbols. This
835 is a rather crude method of making objects disappear since it will affect
836 the entire staff. This method also influences the spacing, which may or
837 may not be desirable. A more
838 sophisticated method of blanking objects is shown in @ref{Common tweaks}.
840 The next example shows a practical application. Bar lines and time
841 signatures are normally synchronized across the score. This is done
842 by the @code{Timing_translator} and @code{Default_bar_line_engraver}.
843 This plug-in keeps an administration of time signature, location
844 within the measure, etc. By moving thes engraver from @code{Score} to
845 @code{Staff} context, we can have a score where each staff has its own
848 @cindex polymetric scores
849 @cindex Time signatures, multiple
851 @lilypond[quote,relative=1,ragged-right,verbatim,fragment]
853 \remove "Timing_translator"
854 \remove "Default_bar_line_engraver"
857 \consists "Timing_translator"
858 \consists "Default_bar_line_engraver"
864 \consists "Timing_translator"
865 \consists "Default_bar_line_engraver"
874 @node Layout tunings within contexts
875 @subsection Layout tunings within contexts
877 Each context is responsible for creating certain types of graphical
878 objects. The settings used for printing these objects are also stored by
879 context. By changing these settings, the appearance of objects can be
882 The syntax for this is
885 \override @var{context}.@var{name} #'@var{property} = #@var{value}
888 Here @var{name} is the name of a graphical object, like @code{Stem} or
889 @code{NoteHead}, and @var{property} is an internal variable of the
890 formatting system (@q{grob property} or @q{layout property}). The latter is a
891 symbol, so it must be quoted. The subsection @ref{Constructing a
892 tweak} explains what to fill in for @var{name}, @var{property}, and
893 @var{value}. Here we only discuss the functionality of this command.
898 \override Staff.Stem #'thickness = #4.0
902 makes stems thicker (the default is 1.3, with staff line thickness as a
903 unit). Since the command specifies @context{Staff} as context, it only
904 applies to the current staff. Other staves will keep their normal
905 appearance. Here we see the command in action:
907 @lilypond[quote,verbatim,relative=2,fragment]
909 \override Staff.Stem #'thickness = #4.0
915 The @code{\override} command changes the definition of the @code{Stem}
916 within the current @context{Staff}. After the command is interpreted
917 all stems are thickened.
919 Analogous to @code{\set}, the @var{context} argument may be left out,
920 causing it to default to @context{Voice}, and adding @code{\once} applies
921 the change during one timestep only
923 @lilypond[quote,fragment,verbatim,relative=2]
925 \once \override Stem #'thickness = #4.0
930 The @code{\override} must be done before the object is
931 started. Therefore, when altering @emph{Spanner} objects such as slurs
932 or beams, the @code{\override} command must be executed at the moment
933 when the object is created. In this example,
935 @lilypond[quote,fragment,verbatim,relative=2]
936 \override Slur #'thickness = #3.0
938 \override Beam #'thickness = #0.6
943 the slur is fatter but the beam is not. This is because the command for
944 @code{Beam} comes after the Beam is started, so it has no effect.
946 Analogous to @code{\unset}, the @code{\revert} command for a context
947 undoes an @code{\override} command; like with @code{\unset}, it only
948 affects settings that were made in the same context. In other words, the
949 @code{\revert} in the next example does not do anything.
952 \override Voice.Stem #'thickness = #4.0
953 \revert Staff.Stem #'thickness
956 Some tweakable options are called @q{subproperties} and reside inside
957 properties. To tweak those, use commands of the form
959 @c leave this as a long long
961 \override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
968 \override Stem #'details #'beamed-lengths = #'(4 4 3)
974 Internals: @internalsref{OverrideProperty}, @internalsref{RevertProperty},
975 @internalsref{PropertySet}, @internalsref{Backend}, and
976 @internalsref{All layout objects}.
981 The back-end is not very strict in type-checking object properties.
982 Cyclic references in Scheme values for properties can cause hangs
986 @node Changing context default settings
987 @subsection Changing context default settings
989 The adjustments of the previous subsections (@ref{Changing context
990 properties on the fly}, @ref{Modifying context plug-ins}, and
991 @ref{Layout tunings within contexts}) can also be entered separately
992 from the music in the @code{\layout} block,
1001 \override Stem #'thickness = #4.0
1002 \remove "Time_signature_engraver"
1007 Here @code{\Staff} takes the existing definition for context @context{Staff} from the
1008 identifier @code{\Staff}.
1013 \override Stem #'thickness = #4.0
1014 \remove "Time_signature_engraver"
1018 affect all staves in the score. Other contexts can be modified
1021 The @code{\set} keyword is optional within the @code{\layout} block, so
1037 It is not possible to collect context changes in a variable and apply
1038 them to a @code{\context} definition by referring to that variable.
1040 The @code{\RemoveEmptyStaffContext} will overwrite your current
1041 @code{\Staff} settings. If you wish to change the defaults for a
1042 staff which uses @code{\RemoveEmptyStaffContext}, you must do so
1043 after calling @code{\RemoveemptyStaffContext}, ie
1048 \RemoveEmptyStaffContext
1050 \override Stem #'thickness = #4.0
1056 @node Defining new contexts
1057 @subsection Defining new contexts
1059 Specific contexts, like @context{Staff} and @code{Voice}, are made of
1060 simple building blocks. It is possible to create new types of
1061 contexts with different combinations of engraver plug-ins.
1063 The next example shows how to build a different type of
1064 @context{Voice} context from scratch. It will be similar to
1065 @code{Voice}, but only prints centered slash noteheads. It can be used
1066 to indicate improvisation in jazz pieces,
1068 @lilypond[quote,ragged-right]
1069 \layout { \context {
1071 \type "Engraver_group"
1072 \consists "Note_heads_engraver"
1073 \consists "Text_engraver"
1074 \consists Pitch_squash_engraver
1075 squashedPosition = #0
1076 \override NoteHead #'style = #'slash
1077 \override Stem #'transparent = ##t
1081 \accepts "ImproVoice"
1085 a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
1086 c4 c^"undress" c_"while playing :)" c }
1092 These settings are defined within a @code{\context} block inside a
1093 @code{\layout} block,
1103 In the following discussion, the example input shown should go on the
1104 @dots{} in the previous fragment.
1106 First the context's name is defined. Instead of @context{Voice} it
1107 will be called @context{ImproVoice},
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
1124 \consists Note_heads_engraver
1125 \consists Text_engraver
1128 but only on the center line,
1131 \consists Pitch_squash_engraver
1132 squashedPosition = #0
1135 The @internalsref{Pitch_squash_engraver} modifies note heads (created
1136 by @internalsref{Note_heads_engraver}) and sets their vertical
1137 position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
1140 The notes look like a slash, and have no stem,
1143 \override NoteHead #'style = #'slash
1144 \override Stem #'transparent = ##t
1147 All these plug-ins have to cooperate, and this is achieved with a
1148 special plug-in, which must be marked with the keyword @code{\type}.
1149 This should always be @internalsref{Engraver_group},
1152 \type "Engraver_group"
1155 Put together, we get
1160 \type "Engraver_group"
1161 \consists "Note_heads_engraver"
1162 \consists "Text_engraver"
1163 \consists Pitch_squash_engraver
1164 squashedPosition = #0
1165 \override NoteHead #'style = #'slash
1166 \override Stem #'transparent = ##t
1172 Contexts form hierarchies. We want to hang the @context{ImproVoice}
1173 under @context{Staff}, just like normal @code{Voice}s. Therefore, we
1174 modify the @code{Staff} definition with the @code{\accepts}
1185 The opposite of @code{\accepts} is @code{\denies},
1186 which is sometimes needed when reusing existing context definitions.
1188 Putting both into a @code{\layout} block, like
1198 \accepts "ImproVoice"
1203 Then the output at the start of this subsection can be entered as
1211 c c_"while playing :)"
1218 @node Aligning contexts
1219 @subsection Aligning contexts
1221 New contexts may be aligned above or below exisiting contexts. This
1222 could be useful in setting up a vocal staff (@ref{Vocal ensembles}) and
1226 @findex alignAboveContext
1227 @findex alignBelowContext
1229 @lilypond[quote,ragged-right]
1230 ossia = { f4 f f f }
1232 \relative c' \new Staff = "main" {
1235 \new Staff \with {alignAboveContext=main} \ossia
1236 { d8 f d f d f d f }
1244 @node The \override command
1245 @section The \override command
1247 In the previous section, we have already touched on a command that
1248 changes layout details: the @code{\override} command. In this section,
1249 we will look in more detail at how to use the command in practice.
1253 * Constructing a tweak::
1254 * Navigating the program reference::
1255 * Layout interfaces::
1256 * Determining the grob property::
1257 * Objects connected to the input::
1258 * \set vs. \override::
1259 * Difficult tweaks::
1264 @node Constructing a tweak
1265 @subsection Constructing a tweak
1267 Commands which change output generally look like
1270 \override Voice.Stem #'thickness = #3.0
1274 This means that we must determine these bits of information:
1277 @item the context: here @context{Voice}.
1278 @item the layout object: here @code{Stem}.
1279 @item the layout property: here @code{thickness}.
1280 @item a sensible value: here @code{3.0}.
1283 Some tweakable options are called @q{subproperties} and reside inside
1284 properties. To tweak those, use commands in the form
1287 \override Stem #'details #'beamed-lengths = #'(4 4 3)
1290 @cindex internal documentation
1291 @cindex finding graphical objects
1292 @cindex graphical object descriptions
1295 @cindex internal documentation
1297 For many properties, regardless of the data type of the property, setting the
1298 property to false ( @code{##f} ) will result in turning it off, causing
1299 Lilypond to ignore that property entirely. This is particularly useful for
1300 turning off grob properties which may otherwise be causing problems.
1302 We demonstrate how to glean this information from the notation manual
1303 and the program reference.
1308 @node Navigating the program reference
1309 @subsection Navigating the program reference
1311 Suppose we want to move the fingering indication in the fragment
1314 @lilypond[quote,fragment,relative=2,verbatim]
1320 If you visit the documentation on fingering instructions (in
1321 @ref{Fingering instructions}), you will notice:
1326 Program reference: @internalsref{Fingering}.
1331 @c outdated info; probably will delete.
1333 This fragment points to two parts of the program reference: a page
1334 on @code{FingerEvent} and one on @code{Fingering}.
1336 The page on @code{FingerEvent} describes the properties of the music
1337 expression for the input @code{-2}. The page contains many links
1338 forward. For example, it says
1341 Accepted by: @internalsref{Fingering_engraver},
1345 That link brings us to the documentation for the Engraver, the
1349 This engraver creates the following layout objects: @internalsref{Fingering}.
1352 In other words, once the @code{FingerEvent}s are interpreted, the
1353 @code{Fingering_engraver} plug-in will process them.
1357 @c I can't figure out what this is supposed to mean. -gp
1359 The @code{Fingering_engraver} is also listed to create
1360 @internalsref{Fingering} objects,
1362 @c old info? it doesn't make any sense to me with our current docs.
1364 second bit of information listed under @b{See also} in the Notation
1368 Follow the link to @internalsref{Fingering}. At the top of the
1372 Fingering objects are created by: @internalsref{Fingering_engraver} and
1373 @internalsref{New_fingering_engraver}.
1376 By clicking around in the program reference, we can follow the
1377 flow of information within the program, following links like this:
1381 @item @internalsref{Fingering}:
1382 @internalsref{Fingering} objects are created by:
1383 @internalsref{Fingering_engraver}
1385 @item @internalsref{Fingering_engraver}:
1386 Music types accepted: @internalsref{fingering-event}
1388 @item @internalsref{fingering-event}:
1389 Music event type @code{fingering-event} is in Music expressions named
1390 @internalsref{FingerEvent}
1393 This path goes against the flow of information in the program: it
1394 starts from the output, and ends at the input event. You could
1395 also start at an input event, and read with the flow of
1396 information, eventually ending up at the output object(s).
1398 The program reference can also be browsed like a normal document. It
1399 contains chapters on
1401 @internalsref{Music definitions},
1404 @code{Music definitions}
1406 on @internalsref{Translation}, and the @internalsref{Backend}. Every
1407 chapter lists all the definitions used and all properties that may be
1411 @node Layout interfaces
1412 @subsection Layout interfaces
1414 @cindex interface, layout
1415 @cindex layout interface
1418 The HTML page that we found in the previous section describes the
1419 layout object called @internalsref{Fingering}. Such an object is a
1420 symbol within the score. It has properties that store numbers (like
1421 thicknesses and directions), but also pointers to related objects. A
1422 layout object is also called a @emph{Grob}, which is short for Graphical
1423 Object. For more details about Grobs, see @internalsref{grob-interface}.
1425 The page for @code{Fingering} lists the definitions for the
1426 @code{Fingering} object. For example, the page says
1429 @code{padding} (dimension, in staff space):
1435 which means that the number will be kept at a distance of at least 0.6
1439 Each layout object may have several functions as a notational or
1440 typographical element. For example, the Fingering object
1441 has the following aspects
1445 Its size is independent of the horizontal spacing, unlike slurs or beams.
1448 It is a piece of text. Granted, it is usually a very short text.
1451 That piece of text is typeset with a font, unlike slurs or beams.
1454 Horizontally, the center of the symbol should be aligned to the
1455 center of the notehead.
1458 Vertically, the symbol is placed next to the note and the staff.
1461 The vertical position is also coordinated with other superscript
1462 and subscript symbols.
1465 Each of these aspects is captured in so-called @emph{interface}s,
1466 which are listed on the @internalsref{Fingering} page at the bottom
1469 This object supports the following interfaces:
1470 @internalsref{item-interface},
1471 @internalsref{self-alignment-interface},
1472 @internalsref{side-position-interface}, @internalsref{text-interface},
1473 @internalsref{text-script-interface}, @internalsref{font-interface},
1474 @internalsref{finger-interface}, and @internalsref{grob-interface}.
1477 Clicking any of the links will take you to the page of the respective
1478 object interface. Each interface has a number of properties. Some of
1479 them are not user-serviceable (@q{Internal properties}), but others
1482 We have been talking of @emph{the} @code{Fingering} object, but actually it
1483 does not amount to much. The initialization file (see
1484 @ref{Default files})
1485 @file{scm/@/define@/-grobs@/.scm} shows the soul of the @q{object},
1490 (avoid-slur . around)
1491 (slur-padding . 0.2)
1492 (staff-padding . 0.5)
1493 (self-alignment-X . 0)
1494 (self-alignment-Y . 0)
1495 (script-priority . 100)
1496 (stencil . ,ly:text-interface::print)
1497 (direction . ,ly:script-interface::calc-direction)
1498 (font-encoding . fetaNumber)
1499 (font-size . -5) ; don't overlap when next to heads.
1500 (meta . ((class . Item)
1501 (interfaces . (finger-interface
1503 text-script-interface
1505 side-position-interface
1506 self-alignment-interface
1507 item-interface))))))
1511 As you can see, the @code{Fingering} object is nothing more than a
1512 bunch of variable settings, and the webpage in the Program Reference
1513 is directly generated from this definition.
1516 @node Determining the grob property
1517 @subsection Determining the grob property
1519 Recall that we wanted to change the position of the @b{2} in
1521 @lilypond[quote,fragment,relative=2,verbatim]
1527 Since the @b{2} is vertically positioned next to its note, we have to
1528 meddle with the interface associated with this positioning. This is
1529 done using @code{side-position-interface}. The page for this interface
1533 @code{side-position-interface}
1535 Position a victim object (this one) next to other objects (the
1536 support). The property @code{direction} signifies where to put the
1537 victim object relative to the support (left or right, up or down?)
1542 Below this description, the variable @code{padding} is described as
1547 (dimension, in staff space)
1549 Add this much extra space between objects that are next to each other.
1553 By increasing the value of @code{padding}, we can move the
1554 fingering away from the notehead. The following command inserts
1555 3 staff spaces of white
1556 between the note and the fingering:
1558 \once \override Voice.Fingering #'padding = #3
1561 Inserting this command before the Fingering object is created,
1562 i.e., before @code{c2}, yields the following result:
1564 @lilypond[quote,relative=2,fragment,verbatim]
1565 \once \override Voice.Fingering #'padding = #3
1572 In this case, the context for this tweak is @context{Voice}. This
1573 fact can also be deduced from the program reference, for the page for
1574 the @internalsref{Fingering_engraver} plug-in says
1577 Fingering_engraver is part of contexts: @dots{} @internalsref{Voice}
1581 @node Objects connected to the input
1582 @subsection Objects connected to the input
1586 In some cases, it is possible to take a short-cut for tuning graphical
1587 objects. For objects that result directly from a piece of the input,
1588 you can use the @code{\tweak} function, for example
1590 @lilypond[relative=2,fragment,verbatim,ragged-right]
1593 \tweak #'color #red d
1595 \tweak #'duration-log #1 a
1596 >4-\tweak #'padding #10 -.
1599 As you can see, properties are set directly in the objects directly,
1600 without mentioning the grob name or context where this should be
1603 This technique only works for objects that are directly connected to
1604 an @internalsref{event} from the input, for example
1607 @item note heads, caused by chord-pitch (i.e., notes inside a chord).
1608 @item articulation signs, caused by articulation instructions.
1611 It notably does not work for stems and accidentals (these are caused
1612 by note heads, not by music events) or clefs (these are not caused by
1613 music inputs, but rather by the change of a property value).
1615 There are very few objects which are @emph{directly} connected to
1616 output. A normal note (like @code{c4}) is not directly connected
1620 \tweak #'color #red c4
1624 will not change color. See @ref{Displaying music expressions} for
1628 @node \set vs. \override
1629 @subsection \set vs. \override
1631 We have seen two methods of changing properties: @code{\set} and
1632 @code{\override}. There are actually two different kinds of
1635 Contexts can have properties, which are usually named in
1636 @code{studlyCaps}. They mostly control the translation from
1637 music to notatino, eg. @code{localKeySignature} (for determining
1638 whether to print accidentals), @code{measurePosition} (for
1639 determining when to print a barline). Context properties can
1640 change value over time while interpreting a piece of music;
1641 @code{measurePosition} is an obvious example of
1642 this. Context properties are modified with @code{\set}.
1644 There is a special type of context property: the element
1645 description. These properties are named in @code{StudlyCaps}
1646 (starting with capital letters). They contain the
1647 @q{default settings} for said graphical object as an
1648 association list. See @file{scm/@/define@/-grobs@/.scm}
1649 to see what kind of settings there are. Element descriptions
1650 may be modified with @code{\override}.
1652 @code{\override} is actually a shorthand;
1655 \override @var{context}.@var{name} #'@var{property} = #@var{value}
1659 is more or less equivalent to
1661 @c leave this long line -gp
1663 \set @var{context}.@var{name} #'@var{property} = #(cons (cons '@var{property} @var{value}) <previous value of @var{context})
1666 The value of @code{context} (the alist) is used to initalize
1667 the properties of individual grobs. Grobs also have
1668 properties, named in Scheme style, with
1669 @code{dashed-words}. The values of grob properties change
1670 during the formatting process: formatting basically amounts
1671 to computing properties using callback functions.
1673 @code{fontSize} is a special property: it is equivalent to
1674 entering @code{\override ... #'font-size} for all pertinent
1675 objects. Since this is a common change, the special
1676 property (modified with @code{\set}) was created.
1679 @node Difficult tweaks
1680 @subsection Difficult tweaks
1682 There are a few classes of difficult adjustments.
1688 One type of difficult adjustment is the appearance of spanner objects,
1689 such as slur and tie. Initially, only one of these objects is created,
1690 and they can be adjusted with the normal mechanism. However, in some
1691 cases the spanners cross line breaks. If this happens, these objects
1692 are cloned. A separate object is created for every system that it is
1693 in. These are clones of the original object and inherit all
1694 properties, including @code{\override}s.
1697 In other words, an @code{\override} always affects all pieces of a
1698 broken spanner. To change only one part of a spanner at a line break,
1699 it is necessary to hook into the formatting process. The
1700 @code{after-line-breaking} callback contains the Scheme procedure that
1701 is called after the line breaks have been determined, and layout
1702 objects have been split over different systems.
1704 In the following example, we define a procedure
1705 @code{my-callback}. This procedure
1709 determines if we have been split across line breaks
1711 if yes, retrieves all the split objects
1713 checks if we are the last of the split objects
1715 if yes, it sets @code{extra-offset}.
1718 This procedure is installed into @internalsref{Tie}, so the last part
1719 of the broken tie is translated up.
1721 @lilypond[quote,verbatim,ragged-right]
1722 #(define (my-callback grob)
1724 ; have we been split?
1725 (orig (ly:grob-original grob))
1727 ; if yes, get the split pieces (our siblings)
1728 (siblings (if (ly:grob? orig)
1729 (ly:spanner-broken-into orig) '() )))
1731 (if (and (>= (length siblings) 2)
1732 (eq? (car (last-pair siblings)) grob))
1733 (ly:grob-set-property! grob 'extra-offset '(-2 . 5)))))
1736 \override Tie #'after-line-breaking =
1743 When applying this trick, the new @code{after-line-breaking} callback
1744 should also call the old one @code{after-line-breaking}, if there is
1745 one. For example, if using this with @code{Hairpin},
1746 @code{ly:hairpin::after-line-breaking} should also be called.
1749 @item Some objects cannot be changed with @code{\override} for
1750 technical reasons. Examples of those are @code{NonMusicalPaperColumn}
1751 and @code{PaperColumn}. They can be changed with the
1752 @code{\outputProperty} function, which works similar to @code{\once
1753 \override}, but uses a different syntax,
1757 #"Score.NonMusicalPaperColumn" % Grob name
1758 #'line-break-system-details % Property name
1759 #'((next-padding . 20)) % Value