The controls available for tuning are described in a separate
document, the
@iftex
-Program reference
+Program reference manual.
@end iftex
@ifnottex
@ref{Top,Program reference,,lilypond-internals}.
@end ifnottex
-manual. That manual
+That manual
lists all different variables, functions and options available in
LilyPond. It is written as a HTML document, which is available
-@uref{http://@/lilypond@/.org/@/doc/@/v2.7/@/Documentation/@/user/@/lilypond@/-internals/,on@/-line},
+@uref{http://@/lilypond@/.org/@/doc/@/v2.8/@/Documentation/@/user/@/
+lilypond@/-internals/,on@/-line},
but is also included with the LilyPond documentation package.
-There are three areas where the default settings may be changed:
+There are four areas where the default settings may be changed:
@itemize @bullet
+@item
+Automatic notation: changing the automatic creation of notation
+elements. For example, changing the beaming rules.
+
@item
Output: changing the appearance of individual
objects. For example, changing stem directions or the location of
subscripts.
-
+
@item
Context: changing aspects of the translation from music events to
-notation. For example, giving each staff a separate time signature.
-
+notation. For example, giving each staff a separate time signature.
+
@item
Global layout: changing the appearance of the spacing, line
-breaks, and page dimensions.
+breaks, and page dimensions. These modifications are discussed
+in @ref{Global issues}.
@end itemize
-Then there are separate systems for typesetting text (like
-@emph{ritardando}) and selecting different fonts. This chapter also
-discusses these.
-
Internally, LilyPond uses Scheme (a LISP dialect) to provide
infrastructure. Overriding layout decisions in effect accesses the
program internals, which requires Scheme input. Scheme elements are
@menu
+* Automatic notation::
* Interpretation contexts::
* The \override command::
@end menu
-
+
+@node Automatic notation
+@section Automatic notation
+
+This section describes how to change the way that accidentals and
+beams are automatically displayed.
+
+@menu
+* Automatic accidentals::
+* Setting automatic beam behavior::
+@end menu
+
+@node Automatic accidentals
+@subsection Automatic accidentals
+@cindex Automatic accidentals
+
+Common rules for typesetting accidentals have been placed in a
+function. This function is called as follows
+
+@findex set-accidental-style
+@example
+#(set-accidental-style 'STYLE #('CONTEXT#))
+@end example
+
+The function can take two arguments: the name of the accidental style,
+and an optional argument that denotes the context that should be
+changed. If no context name is supplied, @code{Staff} is the default,
+but you may wish to apply the accidental style to a single @code{Voice}
+instead.
+
+@c TODO: we should create a very clear example, and show every
+@c accidental style on that example (with the example specially
+@c constructed so that it illustrates all the differences). -gp
+
+The following accidental styles are supported
+@table @code
+@item default
+This is the default typesetting behavior. It corresponds
+to 18th century common practice: Accidentals are
+remembered to the end of the measure in which they occur and
+only on their own octave.
+
+@item voice
+The normal behavior is to remember the accidentals on
+Staff-level. This variable, however, typesets accidentals
+individually for each voice. Apart from that, the rule is similar to
+@code{default}.
+
+As a result, accidentals from one voice do not get canceled in other
+voices, which is often an unwanted result
+
+@lilypond[quote,ragged-right,relative=1,fragment,verbatim]
+\new Staff <<
+ #(set-accidental-style 'voice)
+ <<
+ { es g } \\
+ { c, e }
+>> >>
+@end lilypond
+
+The @code{voice} option should be used if the voices
+are to be read solely by individual musicians. If the staff is to be
+used by one musician (e.g., a conductor) then
+@code{modern} or @code{modern-cautionary}
+should be used instead.
+
+@item modern
+@findex modern style accidentals
+This rule corresponds to the common practice in the 20th century. This rule
+prints the same accidentals as @code{default}, but temporary
+accidentals also are canceled in other octaves. Furthermore,
+in the same octave, they also get canceled in the following
+measure
+
+@lilypond[quote,ragged-right,fragment,verbatim]
+#(set-accidental-style 'modern)
+cis' c'' cis'2 | c'' c'
+@end lilypond
+
+@item @code{modern-cautionary}
+@findex modern-cautionary
+This rule is similar to @code{modern}, but the ``extra'' accidentals
+(the ones not typeset by @code{default}) are typeset as cautionary
+accidentals. They are printed in reduced size or with parentheses
+@lilypond[quote,ragged-right,fragment,verbatim]
+#(set-accidental-style 'modern-cautionary)
+cis' c'' cis'2 | c'' c'
+@end lilypond
+
+@findex modern-voice
+@item modern-voice
+This rule is used for multivoice accidentals to be read both by musicians
+playing one voice and musicians playing all voices. Accidentals are
+typeset for each voice, but they @emph{are} canceled across voices in
+the same @internalsref{Staff}.
+
+@findex modern-voice-cautionary
+@item modern-voice-cautionary
+This rule is the same as @code{modern-voice}, but with the extra
+accidentals (the ones not typeset by @code{voice}) typeset
+as cautionaries. Even though all accidentals typeset by
+@code{default} @emph{are} typeset by this variable,
+some of them are typeset as cautionaries.
+
+@item piano
+@findex piano accidentals
+This rule reflects 20th century practice for piano notation. Very similar to
+@code{modern} but accidentals also get canceled
+across the staves in the same @internalsref{GrandStaff} or
+@internalsref{PianoStaff}.
+
+@item piano-cautionary
+@findex #(set-accidental-style 'piano-cautionary)
+Same as @code{#(set-accidental-style 'piano)} but with the extra
+accidentals typeset as cautionaries.
+
+@item no-reset
+@findex no-reset accidental style
+This is the same as @code{default} but with accidentals lasting
+``forever'' and not only until the next measure
+@lilypond[quote,ragged-right,fragment,verbatim,relative=1]
+#(set-accidental-style 'no-reset)
+c1 cis cis c
+@end lilypond
+
+@item forget
+This is sort of the opposite of @code{no-reset}: Accidentals
+are not remembered at all---and hence all accidentals are
+typeset relative to the key signature, regardless of what was
+before in the music
+
+@lilypond[quote,ragged-right,fragment,verbatim,relative=1]
+#(set-accidental-style 'forget)
+\key d\major c4 c cis cis d d dis dis
+@end lilypond
+@end table
+
+
+@seealso
+
+Program reference: @internalsref{Accidental_engraver},
+@internalsref{Accidental}, and @internalsref{AccidentalPlacement}.
+
+
+@refbugs
+
+Simultaneous notes are considered to be entered in sequential
+mode. This means that in a chord the accidentals are typeset as if the
+notes in the chord happen one at a time, in the order in which
+they appear in the input file. This is a problem when accidentals
+in a chord depend on each other,
+which does not happen for the default accidental style. The problem
+can be solved by manually inserting @code{!} and @code{?} for the
+problematic notes.
+
+
+@node Setting automatic beam behavior
+@subsection Setting automatic beam behavior
+
+@findex autoBeamSettings
+@findex (end * * * *)
+@findex (begin * * * *)
+@cindex automatic beams, tuning
+@cindex tuning automatic beaming
+
+@c [TODO: use \applyContext]
+
+In normal time signatures, automatic beams can start on any note but can
+only end in a few positions within the measure: beams can end on a beat,
+or at durations specified by the properties in
+@code{autoBeamSettings}. The properties in @code{autoBeamSettings}
+consist of a list of rules for where beams can begin and end. The
+default @code{autoBeamSettings} rules are defined in
+@file{scm/@/auto@/-beam@/.scm}.
+
+In order to add a rule to the list, use
+@example
+#(override-auto-beam-setting '(be p q n m) a b [context])
+@end example
+
+@itemize @bullet
+
+@item @code{be} is either "begin" or "end".
+
+@item @code{p/q} is the duration of the note for which you want
+to add a rule. A beam is considered to have the duration of its
+shortest note. Set @code{p} and @code{q} to @code{'*'} to
+have this apply to any beam.
+
+@item @code{n/m} is the time signature to which
+this rule should apply. Set @code{n} and @code{m} to @code{'*'}
+to have this apply in any time signature.
+
+@item @code{a/b} is the position in the bar at which the beam should
+begin/end.
+
+@item @code{context} is optional, and it specifies the context at which
+the change should be made. The default is @code{'Voice}.
+@code{#(score-override-auto-beam-setting '(A B C D) E F)} is equivalent to
+@code{#(override-auto-beam-setting '(A B C D) E F 'Score)}.
+
+@end itemize
+
+For example, if automatic beams should always end on the first quarter
+note, use
+
+@example
+#(override-auto-beam-setting '(end * * * *) 1 4)
+@end example
+
+You can force the beam settings to only take effect on beams whose shortest
+note is a certain duration
+
+@lilypond[quote,fragment,ragged-right,verbatim,relative=2]
+\time 2/4
+#(override-auto-beam-setting '(end 1 16 * *) 1 16)
+a16 a a a a a a a |
+a32 a a a a16 a a a a a |
+#(override-auto-beam-setting '(end 1 32 * *) 1 16)
+a32 a a a a16 a a a a a |
+@end lilypond
+
+You can force the beam settings to only take effect in certain time
+signatures
+
+@lilypond[quote,fragment,ragged-right,verbatim,relative=2]
+\time 5/8
+#(override-auto-beam-setting '(end * * 5 8) 2 8)
+c8 c d d d
+\time 4/4
+e8 e f f e e d d
+\time 5/8
+c8 c d d d
+@end lilypond
+
+You can also remove a previously set beam-ending rule by using
+
+@example
+#(revert-auto-beam-setting '(be p q n m) a b [context])
+@end example
+
+@noindent
+be, p, q, n, m, a, b and context are the same as above. Note that the
+default rules are specified in @file{scm/@/auto@/-beam@/.scm},
+so you can revert rules that you did not explicitly create.
+
+@lilypond[quote,fragment,ragged-right,verbatim,relative=2]
+\time 4/4
+a16 a a a a a a a a a a a a a a a
+#(revert-auto-beam-setting '(end 1 16 4 4) 1 4)
+a16 a a a a a a a a a a a a a a a
+@end lilypond
+
+The rule in a revert-auto-beam-setting statement must exactly match the
+original rule. That is, no wildcard expansion is taken into account.
+
+@lilypond[quote,fragment,ragged-right,verbatim,relative=2]
+\time 1/4
+#(override-auto-beam-setting '(end 1 16 1 4) 1 8)
+a16 a a a
+#(revert-auto-beam-setting '(end 1 16 * *) 1 8) % this won't revert it!
+a a a a
+#(revert-auto-beam-setting '(end 1 16 1 4) 1 8) % this will
+a a a a
+@end lilypond
+
+
+
+@c TODO: old material -- not covered by above stuff, I think.
+If automatic beams should end on every quarter in 5/4 time, specify
+all endings
+@example
+#(override-auto-beam-setting '(end * * * *) 1 4 'Staff)
+#(override-auto-beam-setting '(end * * * *) 1 2 'Staff)
+#(override-auto-beam-setting '(end * * * *) 3 4 'Staff)
+#(override-auto-beam-setting '(end * * * *) 5 4 'Staff)
+@dots{}
+@end example
+
+The same syntax can be used to specify beam starting points. In this
+example, automatic beams can only end on a dotted quarter note
+@example
+#(override-auto-beam-setting '(end * * * *) 3 8)
+#(override-auto-beam-setting '(end * * * *) 1 2)
+#(override-auto-beam-setting '(end * * * *) 7 8)
+@end example
+In 4/4 time signature, this means that automatic beams could end only on
+3/8 and on the fourth beat of the measure (after 3/4, that is 2 times
+3/8, has passed within the measure).
+
+@cindex automatic beam generation
+@cindex autobeam
+@findex autoBeaming
+@cindex lyrics
+
+If beams are used to indicate melismata in songs, then automatic
+beaming should be switched off with @code{\autoBeamOff}.
+
+
+@refcommands
+
+@findex \autoBeamOff
+@code{\autoBeamOff},
+@findex \autoBeamOn
+@code{\autoBeamOn}.
+
+
+@refbugs
+
+If a score ends while an automatic beam has not been ended and is
+still accepting notes, this last beam will not be typeset at all. The
+same holds polyphonic voices, entered with @code{<< @dots{} \\ @dots{}
+>>}. If a polyphonic voice ends while an automatic beam is still
+accepting notes, it is not typeset.
+
+
@node Interpretation contexts
@section Interpretation contexts
+This section describes what contexts are, and how to modify them.
+
+@menu
+* Contexts explained::
+* Creating contexts::
+* Changing context properties on the fly::
+* Modifying context plug-ins::
+* Layout tunings within contexts::
+* Changing context default settings::
+* Defining new contexts::
+@end menu
+
+
+@node Contexts explained
+@subsection Contexts explained
+
When music is printed, a lot of notational elements must be added to the
-input, which is often bare bones. For example, compare the input and
-output of the following example:
+input. For example, compare the input and output of the following example:
@lilypond[quote,verbatim,relative=2,fragment]
cis4 cis2. g4
The input is rather sparse, but in the output, bar lines, accidentals,
clef, and time signature are added. LilyPond @emph{interprets} the
input. During this step, the musical information is inspected in time
-order, similar to reading a score from left to right. While reading,
-the input, the program remembers where measure boundaries are, and what
-pitches need explicit accidentals. This information can be presented on
+order, similar to reading a score from left to right. While reading
+the input, the program remembers where measure boundaries are, and which
+pitches require explicit accidentals. This information can be presented on
several levels. For example, the effect of an accidental is limited
to a single staff, while a bar line must be synchronized across the
entire score.
Within LilyPond, these rules and bits of information are grouped in
-so-called Contexts. Examples of context are @context{Voice},
+@emph{Contexts}. Some examples of contexts are @context{Voice},
@context{Staff}, and @context{Score}. They are hierarchical, for
-example, a @context{Staff} can contain many @context{Voice}s, and a
+example: a @context{Staff} can contain many @context{Voice}s, and a
@context{Score} can contain many @context{Staff} contexts.
+@quotation
+@image{context-example,5cm,,}
+@end quotation
+
Each context has the responsibility for enforcing some notation rules,
creating some notation objects and maintaining the associated
-properties. So, the synchronization of bar lines is handled at
-@context{Score} context. The @context{Voice} may introduce an
+properties. For example, the @context{Voice} context may introduce an
accidental and then the @context{Staff} context maintains the rule to
-show or suppress the accidental for the remainder of the measure.
+show or suppress the accidental for the remainder of the measure. The
+synchronization of bar lines is handled at @context{Score} context.
-For simple scores, contexts are created implicitly, and you need not
-be aware of them. For larger pieces, such as piano music, they must be
+However, in some music we may not want the bar lines to be
+synchronized -- consider a polymetric score in 4/4 and 3/4 time. In
+such cases, we must modify the default settings of the @context{Score}
+and @context{Staff} contexts.
+
+For very simple scores, contexts are created implicitly, and you need
+not be aware of them. For larger pieces, such as anything with more
+than one staff, they must be
created explicitly to make sure that you get as many staves as you
need, and that they are in the correct order. For typesetting pieces
with specialized notation, it can be useful to modify existing or
@ifhtml
@internalsref{Contexts}.
@end ifhtml
-@ifnothtml
+@ifnothtml
Translation @arrow{} Context.
@end ifnothtml
@c [TODO: describe propagation]
-@menu
-* Creating contexts::
-* Changing context properties on the fly::
-* Modifying context plug-ins::
-* Layout tunings within contexts::
-* Changing context default settings::
-* Defining new contexts::
-@end menu
-
@node Creating contexts
@subsection Creating contexts
-For scores with only one voice and one staff, correct contexts are
+For scores with only one voice and one staff, contexts are
created automatically. For more complex scores, it is necessary to
create them by hand. There are three commands that do this.
+@itemize @bullet
+
+@item
The easiest command is @code{\new}, and it also the quickest to type.
It is prepended to a music expression, for example
-@cindex @code{\new}
+@findex \new
@cindex new contexts
@cindex Context, creating
interpreting the @var{music expression} with that.
A practical application of @code{\new} is a score with many
-staves. Each part that should be on its own staff, is preceded with
+staves. Each part that should be on its own staff, is preceded with
@code{\new Staff}.
@lilypond[quote,verbatim,relative=2,ragged-right,fragment]
-<< \new Staff { c4 c }
- \new Staff { d4 d }
+<<
+ \new Staff { c4 c }
+ \new Staff { d4 d }
>>
@end lilypond
-@cindex @code{\context}
+The @code{\new} command may also give a name to the context,
+
+@example
+\new @var{type} = @var{id} @var{music}
+@end example
+However, this user specified name is only used if there is no other
+context already earlier with the same name.
+
+
+@findex \context
+@item
Like @code{\new}, the @code{\context} command also directs a music
-expression to a context object, but gives the context an extra name. The
+expression to a context object, but gives the context an explicit name. The
syntax is
@example
@end example
This form will search for an existing context of type @var{type}
-called @var{id}. If that context does not exist yet, it is created.
-This is useful if the context is referred to later on. For example, when
+called @var{id}. If that context does not exist yet, a new
+context with the specified name is created. This is useful if
+the context is referred to later on. For example, when
setting lyrics the melody is in a named context
@example
so the texts can be properly aligned to its notes,
@example
-\new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
+\new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
@end example
@noindent
-Another possibility is funneling two different music expressions into
-one context. In the following example, articulations and notes are
-entered separately,
+Another possible use of named contexts is funneling two different
+music expressions into one context. In the following example,
+articulations and notes are entered separately,
@example
music = @{ c4 c4 @}
They are combined by sending both to the same @context{Voice} context,
@example
-<< \new Staff \context Voice = "A" \music
- \context Voice = "A" \arts
+<<
+ \new Staff \context Voice = "A" \music
+ \context Voice = "A" \arts
>>
@end example
@lilypond[quote,ragged-right]
@cindex creating contexts
+@item
The third command for creating contexts is
@example
\context @var{type} @var{music}
@code{\context}, it is usually applied to @context{Voice}
@example
-\applyOutput #@var{function} % apply to Voice
+\applyOutput #'@var{context} #@var{function} % apply to Voice
@end example
To have it interpreted at the @context{Score} or @context{Staff} level use
these forms
@example
-\context Score \applyOutput #@var{function}
-\context Staff \applyOutput #@var{function}
+\context \applyOutput #'Score #@var{function}
+\context \applyOutput #'Staff #@var{function}
@end example
+@end itemize
+
@node Changing context properties on the fly
@subsection Changing context properties on the fly
@cindex properties
-@cindex @code{\set}
+@findex \set
@cindex changing properties
Each context can have different @emph{properties}, variables contained
For example,
@lilypond[quote,verbatim,relative=2,fragment]
-R1*2
+R1*2
\set Score.skipBars = ##t
R1*2
@end lilypond
have no effect.
@lilypond[quote,verbatim,relative=2,fragment]
-R1*2
+R1*2
\set skipBars = ##t
R1*2
@end lilypond
`on-the-fly', during the music, so that the setting only affects the
second group of eighth notes.
-@cindex @code{\unset}
+@findex \unset
There is also an @code{\unset} command,
@example
specified for a bottom context, so the two statements
@example
-\set Voice.autoBeaming = ##t
-\set autoBeaming = ##t
-@end example
+\set Voice.autoBeaming = ##t
+\set autoBeaming = ##t
+@end example
@noindent
are equivalent.
@node Modifying context plug-ins
@subsection Modifying context plug-ins
-Notation contexts (like Score and Staff) not only store properties,
-they also contain plug-ins, called ``engravers'' that create notation
-elements. For example, the Voice context contains a
-@code{Note_head_engraver} and the Staff context contains a
+Notation contexts (like @code{Score} and @code{Staff}) not only
+store properties,
+they also contain plug-ins called ``engravers'' that create notation
+elements. For example, the @code{Voice} context contains a
+@code{Note_head_engraver} and the @code{Staff} context contains a
@code{Key_signature_engraver}.
-For a full a description of each plug-in, see
+For a full a description of each plug-in, see
@ifhtml
@internalsref{Engravers}.
@end ifhtml
@ifhtml
@internalsref{Contexts}
@end ifhtml
-@ifnothtml
+@ifnothtml
Program reference @arrow Translation @arrow{} Context.
@end ifnothtml
lists the engravers used for that context.
It can be useful to shuffle around these plug-ins. This is done by
-starting a new context, with @code{\new} or @code{\context}, and
-modifying it like this,
+starting a new context with @code{\new} or @code{\context}, and
+modifying it,
-@cindex @code{\with}
+@findex \with
@example
\new @var{context} \with @{
\remove @dots{}
@emph{etc.}
@}
-@emph{..music..}
+@{
+ @emph{..music..}
+@}
@end example
@noindent
@code{Clef_engraver} from a @code{Staff} context,
@lilypond[quote,relative=1,verbatim,fragment]
-<< \new Staff {
+<<
+ \new Staff {
f2 g
}
\new Staff \with {
In the second staff there are no time signature or clef symbols. This
is a rather crude method of making objects disappear since it will affect
-the entire staff. The spacing is adversely influenced too. A more
+the entire staff. This method also influences the spacing, which may or
+may not be desirable. A more
sophisticated method of blanking objects is shown in @ref{Common tweaks}.
The next example shows a practical application. Bar lines and time
objects. The settings used for printing these objects are also stored by
context. By changing these settings, the appearance of objects can be
altered.
-
+
The syntax for this is
@example
The command
@verbatim
-\override Staff.Stem #'thickness = #4.0
+\override Staff.Stem #'thickness = #4.0
@end verbatim
@noindent
@lilypond[quote,verbatim,relative=2,fragment]
c4
-\override Staff.Stem #'thickness = #4.0
+\override Staff.Stem #'thickness = #4.0
c4
c4
c4
Analogous to @code{\set}, the @var{context} argument may be left out,
causing it to default to @context{Voice}, and adding @code{\once} applies
-the change during one timestep only
+the change during one timestep only
@lilypond[quote,fragment,verbatim,relative=2]
c4
-\once \override Stem #'thickness = #4.0
+\once \override Stem #'thickness = #4.0
+c4
c4
-c4
@end lilypond
The @code{\override} must be done before the object is
-started. Therefore, when altering @emph{Spanner} objects, like slurs or
-beams, the @code{\override} command must be executed at the moment when
-the object is created. In this example,
-
+started. Therefore, when altering @emph{Spanner} objects such as slurs
+or beams, the @code{\override} command must be executed at the moment
+when the object is created. In this example,
@lilypond[quote,fragment,verbatim,relative=2]
\override Slur #'thickness = #3.0
c8[( c
\override Beam #'thickness = #0.6
-c8 c])
+c8 c])
@end lilypond
@noindent
the slur is fatter but the beam is not. This is because the command for
-@code{Beam} comes after the Beam is started. Therefore it has no effect.
+@code{Beam} comes after the Beam is started, so it has no effect.
Analogous to @code{\unset}, the @code{\revert} command for a context
undoes an @code{\override} command; like with @code{\unset}, it only
@end example
Some tweakable options are called ``subproperties'' and reside inside
-properties. To tweak those, use
+properties. To tweak those, use commands of the form
+@c leave this as a long long
@example
-\override Stem #'details #'beamed-lengths = #'(4 4 3)
+\override @var{context}.@var{name} #'@var{property} #'@var{subproperty} = #@var{value}
+@end example
+
+@noindent
+such as
+
+@example
+\override Stem #'details #'beamed-lengths = #'(4 4 3)
@end example
The adjustments of the previous subsections (@ref{Changing context
properties on the fly}, @ref{Modifying context plug-ins}, and
@ref{Layout tunings within contexts}) can also be entered separately
-from the music, in the @code{\layout} block,
+from the music in the @code{\layout} block,
@example
\layout @{
@}
@end example
-Here
-@example
-\Staff
-@end example
-
-@noindent
-takes the existing definition for context @context{Staff} from the
-identifier @code{\Staff}.
+Here @code{\Staff} takes the existing definition for context @context{Staff} from the
+identifier @code{\Staff}.
The statements
@example
@end example
@noindent
-affect all staves in the score.
-
-Other contexts can be modified analogously.
+affect all staves in the score. Other contexts can be modified
+analogously.
The @code{\set} keyword is optional within the @code{\layout} block, so
@refbugs
-It is not possible to collect context changes in a variable, and apply
-them to one @code{\context} definition by referring to that variable.
+It is not possible to collect context changes in a variable and apply
+them to a @code{\context} definition by referring to that variable.
-The @code{\RemoveEmptyStaffContext} will override your current
-@code{\Staff} variable. If you wish to change the defaults for a
-staff that uses @code{\RemoveEmptyStaffContext}, you must do so
+The @code{\RemoveEmptyStaffContext} will overwrite your current
+@code{\Staff} settings. If you wish to change the defaults for a
+staff which uses @code{\RemoveEmptyStaffContext}, you must do so
after calling @code{\RemoveemptyStaffContext}, ie
@example
@subsection Defining new contexts
Specific contexts, like @context{Staff} and @code{Voice}, are made of
-simple building blocks, and it is possible to compose engraver
-plug-ins in different combinations, thereby creating new types of
-contexts.
+simple building blocks. It is possible to create new types of
+contexts with different combinations of engraver plug-ins.
The next example shows how to build a different type of
@context{Voice} context from scratch. It will be similar to
-@code{Voice}, but prints centered slash noteheads only. It can be used
-to indicate improvisation in Jazz pieces,
+@code{Voice}, but only prints centered slash noteheads. It can be used
+to indicate improvisation in jazz pieces,
@lilypond[quote,ragged-right]
\layout { \context {
}}
\relative c'' {
- a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
- c4 c^"undress" c_"while playing :)" c }
- a1
+ a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
+ c4 c^"undress" c_"while playing :)" c }
+ a1
}
@end lilypond
-These settings are again done within a @code{\context} block inside a
+These settings are defined within a @code{\context} block inside a
@code{\layout} block,
@example
In the following discussion, the example input shown should go on the
@dots{} in the previous fragment.
-First, the context gets a name. Instead of @context{Voice} it
+First the context's name is defined. Instead of @context{Voice} it
will be called @context{ImproVoice},
@example
position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
the center line.
-The notes look like a slash, without a stem,
+The notes look like a slash, and have no stem,
@example
\override NoteHead #'style = #'slash
\override Stem #'transparent = ##t
@end example
-
All these plug-ins have to cooperate, and this is achieved with a
special plug-in, which must be marked with the keyword @code{\type}.
This should always be @internalsref{Engraver_group},
@}
@end example
+@findex \accepts
Contexts form hierarchies. We want to hang the @context{ImproVoice}
under @context{Staff}, just like normal @code{Voice}s. Therefore, we
modify the @code{Staff} definition with the @code{\accepts}
-command,@footnote{The opposite of @code{\accepts} is @code{\denies},
-which is sometimes needed when reusing existing context definitions.}
-
-
+command,
@example
\context @{
\Staff
- \accepts ImproVoice
+ \accepts ImproVoice
@}
@end example
+@findex \denies
+The opposite of @code{\accepts} is @code{\denies},
+which is sometimes needed when reusing existing context definitions.
+
Putting both into a @code{\layout} block, like
@example
\relative c'' @{
a4 d8 bes8
\new ImproVoice @{
- c4^"ad lib" c
+ c4^"ad lib" c
c4 c^"undress"
c c_"while playing :)"
@}
a1
@}
@end example
-
-
+
+
@node The \override command
@section The \override command
In the previous section, we have already touched on a command that
changes layout details: the @code{\override} command. In this section,
we will look in more detail at how to use the command in practice.
-First, we will give a few versatile commands that are sufficient
-for many situations. The next section will discuss the general use of
-@code{\override}.
@menu
-* Common tweaks::
* Constructing a tweak::
* Navigating the program reference::
* Layout interfaces::
* Determining the grob property::
* Objects connected to the input::
+* \set vs. \override::
* Difficult tweaks::
@end menu
-@node Common tweaks
-@subsection Common tweaks
-
-@c Should we point at ly/property-init.ly ? -gp
-Some overrides are so common that predefined commands are provided as
-short-cuts, for example, @code{\slurUp} and @code{\stemDown}. These
-commands are described in
-@ifhtml
-the
-@end ifhtml
-@c @ref{Notation manual},
-Notation manual
-@c FIXME
-under the sections for slurs and stems
-respectively.
-
-The exact tuning possibilities for each type of layout object are
-documented in the program reference of the respective
-object. However, many layout objects share properties, which can be
-used to apply generic tweaks. We mention a few of these:
-
-@itemize @bullet
-@item The @code{extra-offset} property, which
-@cindex @code{extra-offset}
-has a pair of numbers as value, moves objects around in the printout.
-The first number controls left-right movement; a positive number will
-move the object to the right. The second number controls up-down
-movement; a positive number will move it higher. The units of these
-offsets are staff-spaces. The @code{extra-offset} property is a
-low-level feature: the formatting engine is completely oblivious to
-these offsets.
-
-In the following example, the second fingering is moved a little to
-the left, and 1.8 staff space downwards:
-
-@cindex setting object properties
-
-@lilypond[quote,fragment,relative=1,verbatim]
-\stemUp
-f-5
-\once \override Fingering
- #'extra-offset = #'(-0.3 . -1.8)
-f-5
-@end lilypond
-
-@item
-Setting the @code{transparent} property will cause an object to be printed
-in `invisible ink': the object is not printed, but all its other
-behavior is retained. The object still takes up space, it takes part in
-collisions, and slurs, ties, and beams can be attached to it.
-
-@cindex transparent objects
-@cindex removing objects
-@cindex hiding objects
-@cindex invisible objects
-The following example demonstrates how to connect different voices
-using ties. Normally, ties only connect two notes in the same
-voice. By introducing a tie in a different voice,
-
-@lilypond[quote,fragment,relative=2]
-<< {
- b8~ b8\noBeam
-} \\ {
- b[ g8]
-} >>
-@end lilypond
-
-@noindent
-and blanking the first up-stem in that voice, the tie appears to cross
-voices:
-
-@lilypond[quote,fragment,relative=2,verbatim]
-<< {
- \once \override Stem #'transparent = ##t
- b8~ b8\noBeam
-} \\ {
- b[ g8]
-} >>
-@end lilypond
-
-@item
-The @code{padding} property for objects with
-@cindex @code{padding}
-@code{side-position-interface} can be set to increase the distance between
-symbols that are printed above or below notes. We provide two
-examples; a more elaborate explanation is in @ref{Constructing a
-tweak}:
-
-@lilypond[quote,fragment,relative=1,verbatim]
-c2\fermata
-\override Script #'padding = #3
-b2\fermata
-@end lilypond
-
-@lilypond[quote,fragment,relative=1,verbatim]
-% This will not work, see below:
-\override MetronomeMark #'padding = #3
-\tempo 4=120
-c1
-% This works:
-\override Score.MetronomeMark #'padding = #3
-\tempo 4=80
-d1
-@end lilypond
-
-Note in the second example how important it is to figure out what
-context handles a certain object. Since the @code{MetronomeMark} object
-is handled in the Score context, property changes in the @code{Voice}
-context will not be noticed.
-
-@end itemize
-
-Some tweakable options are called ``subproperties'' and reside inside
-properties. To tweak those, use
-
-@example
-\override Stem #'details #'beamed-lengths = #'(4 4 3)
-@end example
-
-
-More specific overrides are also possible. The next section
-discusses in depth how to figure out these statements for yourself.
-
-
@node Constructing a tweak
@subsection Constructing a tweak
-The general procedure of changing output, that is, entering
-a command like
+Commands which change output generally look like
@example
\override Voice.Stem #'thickness = #3.0
@end example
@noindent
-means that we have to determine these bits of information:
+This means that we must determine these bits of information:
@itemize
@item the context: here @context{Voice}.
@item the layout object: here @code{Stem}.
-@item the layout property: here @code{thickness}
-@item a sensible value: here @code{3.0}
-@end itemize
+@item the layout property: here @code{thickness}.
+@item a sensible value: here @code{3.0}.
+@end itemize
+Some tweakable options are called ``subproperties'' and reside inside
+properties. To tweak those, use commands in the form
+
+@example
+\override Stem #'details #'beamed-lengths = #'(4 4 3)
+@end example
@cindex internal documentation
@cindex finding graphical objects
-@cindex graphical object descriptions
+@cindex graphical object descriptions
@cindex tweaking
-@cindex @code{\override}
+@findex \override
@cindex internal documentation
We demonstrate how to glean this information from the notation manual
and the program reference.
+
@node Navigating the program reference
@subsection Navigating the program reference
@end lilypond
If you visit the documentation on fingering instructions (in
-@ref{Fingering instructions}), you will notice that there is written:
+@ref{Fingering instructions}), you will notice:
@quotation
@seealso
-Program reference: @internalsref{FingerEvent} and @internalsref{Fingering}.
+Program reference: @internalsref{Fingering}.
@end quotation
-
+@c outdated info; probably will delete.
+@ignore
This fragment points to two parts of the program reference: a page
on @code{FingerEvent} and one on @code{Fingering}.
@quotation
Accepted by: @internalsref{Fingering_engraver},
-@end quotation
+@end quotation
@noindent
That link brings us to the documentation for the Engraver, the
In other words, once the @code{FingerEvent}s are interpreted, the
@code{Fingering_engraver} plug-in will process them.
+@end ignore
+
+@ignore
+@c I can't figure out what this is supposed to mean. -gp
+
The @code{Fingering_engraver} is also listed to create
@internalsref{Fingering} objects,
-
-Lo and behold, that is also the
+@c old info? it doesn't make any sense to me with our current docs.
+This is also the
second bit of information listed under @b{See also} in the Notation
-manual. By clicking around in the program reference, we can follow the
-flow of information within the program, either forward (like we did
-here), or backwards, following links like this:
+manual.
+@end ignore
+
+Follow the link to @internalsref{Fingering}. At the top of the
+page, you will see
+
+@quotation
+Fingering objects are created by: @internalsref{Fingering_engraver} and
+@internalsref{New_fingering_engraver}.
+@end quotation
+
+By clicking around in the program reference, we can follow the
+flow of information within the program, following links like this:
@itemize @bullet
@item @internalsref{Fingering}:
@internalsref{Fingering} objects are created by:
-@b{@internalsref{Fingering_engraver}}
+@internalsref{Fingering_engraver}
@item @internalsref{Fingering_engraver}:
-Music types accepted: @b{@internalsref{fingering-event}}
+Music types accepted: @internalsref{fingering-event}
@item @internalsref{fingering-event}:
Music event type @code{fingering-event} is in Music expressions named
-@b{@internalsref{FingerEvent}}
+@internalsref{FingerEvent}
@end itemize
This path goes against the flow of information in the program: it
-starts from the output, and ends at the input event.
+starts from the output, and ends at the input event. You could
+also start at an input event, and read with the flow of
+information, eventually ending up at the output object(s).
The program reference can also be browsed like a normal document. It
-contains a chapter on
+contains chapters on
@ifhtml
@internalsref{Music definitions},
@end ifhtml
@code{Music definitions}
@end ifnothtml
on @internalsref{Translation}, and the @internalsref{Backend}. Every
-chapter lists all the definitions used, and all properties that may be
+chapter lists all the definitions used and all properties that may be
tuned.
-
+
@node Layout interfaces
@subsection Layout interfaces
@cindex layout interface
@cindex grob
-The HTML page that we found in the previous section, describes the
+The HTML page that we found in the previous section describes the
layout object called @internalsref{Fingering}. Such an object is a
symbol within the score. It has properties that store numbers (like
thicknesses and directions), but also pointers to related objects. A
@quotation
@code{padding} (dimension, in staff space):
-
-@code{0.6}
+
+@code{0.5}
@end quotation
@noindent
Vertically, the symbol is placed next to the note and the staff.
@item
-The vertical position is also coordinated with other super- and subscript
-symbols.
+The vertical position is also coordinated with other superscript
+and subscript symbols.
@end itemize
Each of these aspects is captured in so-called @emph{interface}s,
Clicking any of the links will take you to the page of the respective
object interface. Each interface has a number of properties. Some of
them are not user-serviceable (``Internal properties''), but others
-are.
+can be modified.
We have been talking of @emph{the} @code{Fingering} object, but actually it
-does not amount to much. The initialization file
+does not amount to much. The initialization file (see
+@ref{Default files})
@file{scm/@/define@/-grobs@/.scm} shows the soul of the `object',
@example
bunch of variable settings, and the webpage in the Program Reference
is directly generated from this definition.
+
@node Determining the grob property
@subsection Determining the grob property
-
-Recall that we wanted to change the position of the @b{2} in
+Recall that we wanted to change the position of the @b{2} in
@lilypond[quote,fragment,relative=2,verbatim]
c-2
Since the @b{2} is vertically positioned next to its note, we have to
meddle with the interface associated with this positioning. This is
-done using @code{side-position-interface}. The page for this interface
+done using @code{side-position-interface}. The page for this interface
says
@quotation
@cindex padding
@noindent
-below this description, the variable @code{padding} is described as
+Below this description, the variable @code{padding} is described as
@quotation
@table @code
@item padding
(dimension, in staff space)
-Add this much extra space between objects that are next to each other.
+Add this much extra space between objects that are next to each other.
@end table
@end quotation
-By increasing the value of @code{padding}, we can move away the
-fingering. The following command inserts 3 staff spaces of white
+By increasing the value of @code{padding}, we can move the
+fingering away from the notehead. The following command inserts
+3 staff spaces of white
between the note and the fingering:
@example
\once \override Voice.Fingering #'padding = #3
the @internalsref{Fingering_engraver} plug-in says
@quotation
-Fingering_engraver is part of contexts: @dots{} @b{@internalsref{Voice}}
+Fingering_engraver is part of contexts: @dots{} @internalsref{Voice}
@end quotation
+
@node Objects connected to the input
@subsection Objects connected to the input
+@findex \tweak
+
In some cases, it is possible to take a short-cut for tuning graphical
objects. For objects that result directly from a piece of the input,
you can use the @code{\tweak} function, for example
\tweak #'color #red d
g
\tweak #'duration-log #1 a
->4-\tweak #'padding #10 -.
+>4-\tweak #'padding #10 -.
@end lilypond
As you can see, properties are set directly in the objects directly,
an @internalsref{event} from the input, for example
@itemize @bullet
-@item note heads, caused by chord-pitch.
-@item articulation signs, caused by articulation instructions
+@item note heads, caused by chord-pitch (i.e., notes inside a chord).
+@item articulation signs, caused by articulation instructions.
@end itemize
It notably does not work for stems and accidentals (these are caused
-by note heads, not by music events), clefs (these are not caused by
+by note heads, not by music events) or clefs (these are not caused by
music inputs, but rather by the change of a property value).
-
-In a similar vein, objects may be parenthesized by prefixing
-@code{\parenthesize} to the music event,
-@lilypond[relative=2,fragment,verbatim,ragged-right]
-<
- c
- \parenthesize d
- g
->4-\parenthesize -.
-@end lilypond
+There are very few objects which are @emph{directly} connected to
+output. A normal note (like @code{c4}) is not directly connected
+to output, so
+
+@example
+\tweak #'color #red c4
+@end example
+
+@noindent
+will not change color. See @ref{Displaying music expressions} for
+details.
+
+
+@node \set vs. \override
+@subsection \set vs. \override
+
+We have seen two methods of changing properties: @code{\set} and
+@code{\override}. There are actually two different kinds of
+properties.
+Contexts can have properties, which are usually named in
+@code{studlyCaps}. They mostly control the translation from
+music to notatino, eg. @code{localKeySignature} (for determining
+whether to print accidentals), @code{measurePosition} (for
+determining when to print a barline). Context properties can
+change value over time while interpreting a piece of music;
+@code{measurePosition} is an obvious example of
+this. Context properties are modified with @code{\set}.
+There is a special type of context property: the element
+description. These properties are named in @code{StudlyCaps}
+(starting with capital letters). They contain the
+``default settings'' for said graphical object as an
+association list. See @file{scm/@/define@/-grobs@/.scm}
+to see what kind of settings there are. Element descriptions
+may be modified with @code{\override}.
+
+@code{\override} is actually a shorthand;
+
+@example
+\override @var{context}.@var{name} #'@var{property} = #@var{value}
+@end example
+
+@noindent
+is more or less equivalent to
+
+@c leave this long line -gp
+@example
+\set @var{context}.@var{name} #'@var{property} = #(cons (cons '@var{property} @var{value}) <previous value of @var{context})
+@end example
+
+The value of @code{context} (the alist) is used to initalize
+the properties of individual grobs. Grobs also have
+properties, named in scheme style, with
+@code{dashed-words}. The values of grob properties change
+during the formatting process: formatting basically amounts
+to computing properties using callback functions.
+
+@code{fontSize} is a special property: it is equivalent to
+entering @code{\override ... #'font-size} for all pertinent
+objects. Since this is a common change, the special
+property (modified with @code{\set}) was created.
@node Difficult tweaks
@subsection Difficult tweaks
-There are a few classes of difficult adjustments.
+There are a few classes of difficult adjustments.
@itemize @bullet
@item
-Another difficult adjustment is the appearance of spanner objects,
+One type of difficult adjustment is the appearance of spanner objects,
such as slur and tie. Initially, only one of these objects is created,
and they can be adjusted with the normal mechanism. However, in some
cases the spanners cross line breaks. If this happens, these objects
In the following example, we define a procedure
@code{my-callback}. This procedure
-
+
@itemize @bullet
@item
determines if we have been split across line breaks
@lilypond[quote,verbatim,ragged-right]
#(define (my-callback grob)
(let* (
- ; have we been split?
+ ; have we been split?
(orig (ly:grob-original grob))
; if yes, get the split pieces (our siblings)
(eq? (car (last-pair siblings)) grob))
(ly:grob-set-property! grob 'extra-offset '(-2 . 5)))))
-\relative c'' {
+\relative c'' {
\override Tie #'after-line-breaking =
#my-callback
c1 ~ \break c2 ~ c
@code{\outputProperty} function, which works similar to @code{\once
\override}, but uses a different syntax,
-@example
+@example
\outputProperty
#"Score.NonMusicalPaperColumn" % Grob name
-#'line-break-system-details % Property name
+#'line-break-system-details % Property name
#'((next-padding . 20)) % Value
@end example
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