Guide, node Updating translation committishes..
@end ignore
-@c \version "2.17.6"
+@c \version "2.17.20"
@node Changing defaults
@chapter Changing defaults
@menu
* Contexts explained::
-* Creating contexts::
+* Creating and referencing contexts::
* Keeping contexts alive::
* Modifying context plug-ins::
* Changing context default settings::
@unnumberedsubsubsec Bottom-level contexts - voices
Voice-level contexts initialise certain properties and start
-appropriate engravers. Being bottom-level contexts, they cannot
-contain other contexts.
+appropriate engravers. A bottom-level context is one without
+@code{defaultchild}. While it is possible to let it
+accept/@/contain subcontexts, they can only be created and entered
+explicitly.
@strong{@emph{Voice}}
@end ignore
-@node Creating contexts
-@subsection Creating contexts
-
-@c TODO more complete descriptions rather than learning style
-
-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
-
-@item
-The easiest command is @code{\new}, and it also the quickest to type.
-It is prepended to a music expression, for example
+@node Creating and referencing contexts
+@subsection Creating and referencing contexts
@funindex \new
+@funindex \context
@cindex new contexts
-@cindex Context, creating
+@cindex referencing contexts
+@cindex Contexts, creating and referencing
+
+LilyPond will create lower-level contexts automatically if a music
+expression is encountered before a suitable context exists, but this
+is usually successful only for simple scores or music fragments like
+the ones in the documentation. For more complex scores it is
+advisable to specify all contexts explicitly with either the
+@code{\new} or @code{\context} command. The syntax of
+these two commands is very similar:
@example
-\new @var{type} @var{music expression}
+[\new | \context] @var{Context} [ = @var{name}] [@var{music-expression}]
@end example
@noindent
-where @var{type} is a context name (like @code{Staff} or
-@code{Voice}). This command creates a new context, and starts
-interpreting the @var{music expression} with that.
+where either @code{\new} or @code{\context} may be specified.
+@var{Context} is the type of context which is to be created,
+@var{name} is an optional name to be given to the particular context
+being created and @var{music-expression} is a single music expression
+that is to be interpreted by the engravers and performers in this
+context.
-A practical application of @code{\new} is a score with many
-staves. Each part that should be on its own staff, is preceded with
-@code{\new Staff}.
+The @code{\new} prefix without a name is commonly used to create
+scores with many staves:
-@lilypond[quote,verbatim,relative=2,ragged-right]
+@lilypond[quote,verbatim,relative=2]
<<
- \new Staff { c4 c }
- \new Staff { d4 d }
+ \new Staff {
+ % leave the Voice context to be created implicitly
+ c4 c
+ }
+ \new Staff {
+ d4 d
+ }
>>
@end lilypond
-The @code{\new} command may also give a name to the context,
+@noindent
+and to place several voices into one staff:
-@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.
+@lilypond[quote,verbatim,relative=2]
+<<
+ \new Staff <<
+ \new Voice {
+ \voiceOne
+ c8 c c4 c c
+ }
+ \new Voice {
+ \voiceTwo
+ g4 g g g
+ }
+ >>
+>>
+@end lilypond
+@noindent
+@code{\new} should always be used to specify unnamed contexts.
-@funindex \context
+The difference between @code{\new} and @code{\context} is in the
+action taken:
+@itemize
@item
-Like @code{\new}, the @code{\context} command also directs a music
-expression to a context object, but gives the context an explicit name. The
-syntax is
+@code{\new} with or without a name will always create a fresh,
+distinct, context, even if one with the same name already exists:
-@example
-\context @var{type} = @var{id} @var{music}
-@end example
+@lilypond[quote,verbatim,relative=2]
+<<
+ \new Staff <<
+ \new Voice = "A" {
+ \voiceOne
+ c8 c c4 c c
+ }
+ \new Voice = "A" {
+ \voiceTwo
+ g4 g g g
+ }
+ >>
+>>
+@end lilypond
-This form will search for an existing context of type @var{type}
-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
+@item
+@code{\context} with a name specified will create a distinct context
+only if a context of the same type with the same name in the same
+context hierarchy does not already exist. Otherwise it will be taken
+as a reference to that previously created context, and its music
+expression will be passed to that context for interpretation.
-@example
-\context Voice = "@b{tenor}" @var{music}
-@end example
+One application of named contexts is in separating the score layout
+from the musical content. Either of these two forms is valid:
-@noindent
-so the texts can be properly aligned to its notes,
+@lilypond[quote,verbatim]
+\score {
+ <<
+ % score layout
+ \new Staff <<
+ \new Voice = "one" {
+ \voiceOne
+ }
+ \new Voice = "two" {
+ \voiceTwo
+ }
+ >>
-@example
-\new Lyrics \lyricsto "@b{tenor}" @var{lyrics}
-@end example
+ % musical content
+ \context Voice = "one" {
+ \relative c'' {
+ c4 c c c
+ }
+ }
+ \context Voice = "two" {
+ \relative c'' {
+ g8 g g4 g g
+ }
+ }
+ >>
+}
+@end lilypond
-@noindent
+@lilypond[quote,verbatim]
+\score {
+ <<
+ % score layout
+ \new Staff <<
+ \context Voice = "one" {
+ \voiceOne
+ }
+ \context Voice = "two" {
+ \voiceTwo
+ }
+ >>
-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,
+ % musical content
+ \context Voice = "one" {
+ \relative c'' {
+ c4 c c c
+ }
+ }
+ \context Voice = "two" {
+ \relative c'' {
+ g8 g g4 g g
+ }
+ }
+ >>
+}
+@end lilypond
-@example
-music = @{ c4 c4 @}
-arts = @{ s4-. s4-> @}
-@end example
+@noindent
+Alternatively, variables may be employed to similar effect. See
+@rlearning{Organizing pieces with variables}.
-They are combined by sending both to the same @code{Voice} context,
+@item
+
+@code{\context} with no name will match the first of any previously
+created contexts of the same type in the same context heirarchy,
+even one that has been given a name, and its music expression will be
+passed to that context for interpretation. This form is rarely
+useful. However, @code{\context} with no name and no music expression
+is used to set the context in which a Scheme procedure specified with
+@code{\applyContext} is executed:
@example
-<<
- \new Staff \context Voice = "A" \music
- \context Voice = "A" \arts
->>
+\new Staff \relative c' @{
+ c1
+ \context Timing
+ \applyContext #(lambda (ctx)
+ (newline)
+ (display (ly:context-current-moment ctx)))
+ c1
+@}
@end example
-@lilypond[quote,ragged-right]
-music = { c4 c4 }
-arts = { s4-. s4-> }
-\relative c'' <<
- \new Staff \context Voice = "A" \music
- \context Voice = "A" \arts
->>
-@end lilypond
-With this mechanism, it is possible to define an Urtext (original
-edition), with the option to put several distinct articulations on the
-same notes.
+@end itemize
-@cindex creating contexts
+A context must be named if it is to be referenced later, for example
+when lyrics are associated with music:
-@item
-The third command for creating contexts is
@example
-\context @var{type} @var{music}
+\new Voice = "tenor" @var{music}
+@dots{}
+\new Lyrics \lyricsto "tenor" @var{lyrics}
@end example
-
@noindent
-This is similar to @code{\context} with @code{= @var{id}}, but matches
-any context of type @var{type}, regardless of its given name.
+For details of associating lyrics with music see
+@ref{Automatic syllable durations}.
-This variant is used with music expressions that can be interpreted at
-several levels. For example, the @code{\applyOutput} command (see
-@rextend{Running a function on all layout objects}). Without an explicit
-@code{\context}, it is usually applied to @code{Voice}
+The properties of all contexts of a particular type can be modified
+in a @code{\layout} block (with a different syntax), see
+@ref{Changing all contexts of the same type}. This construct also
+provides a means of keeping layout instructions separate from the
+musical content. If a single context is to be modified, a @code{\with}
+block must be used, see @ref{Changing just one specific context}.
-@example
-\applyOutput #'@var{context} #@var{function} % apply to Voice
-@end example
+@seealso
-To have it interpreted at the @code{Score} or @code{Staff} level use
-these forms
+Learning Manual:
+@rlearning{Organizing pieces with variables}.
-@example
-\applyOutput #'Score #@var{function}
-\applyOutput #'Staff #@var{function}
-@end example
+Notation Reference:
+@ref{Changing just one specific context},
+@ref{Automatic syllable durations}.
-@end itemize
@node Keeping contexts alive
@subsection Keeping contexts alive
There is an exception to this general rule: just one of the
@code{Voice} contexts in a @code{Staff} context or in a
-@code{<<...>>} construct will always persist to the end of the
-enclosing @code{Staff} context or @code{<<...>>} construct, even
+@code{<<@dots{}>>} construct will always persist to the end of the
+enclosing @code{Staff} context or @code{<<@dots{}>>} construct, even
though there may be periods when it has nothing to do. The context
to persist in this way will be the first one encountered in the
-first enclosed @code{@{...@}} construct, ignoring any in enclosed
-@code{<<...>>} constructs.
+first enclosed @code{@{@dots{}@}} construct, ignoring any in enclosed
+@code{<<@dots{}>>} constructs.
Any context can be kept alive by ensuring it has something to do at
every musical moment. @code{Staff} contexts are kept alive by
@emph{etc.}
@}
@{
- @emph{..music..}
+ @emph{@dots{}music@dots{}}
@}
@end example
\with @{
[context settings for this context instance only]
@} @{
-...
+ @dots{}
@}
@end example
@funindex \denies
@funindex denies
-Specific contexts, like @code{Staff} and @code{Voice}, are made of
+Specific contexts, like @code{Staff} and @code{Voice}, are made from
simple building blocks. It is possible to create new types of
contexts with different combinations of engraver plug-ins.
squashedPosition = #0
\override NoteHead.style = #'slash
\override Stem.transparent = ##t
- \override Flag.transparent = ##t
\alias Voice
}
\context { \Staff
\name ImproVoice
@end example
-Since it is similar to the @code{Voice}, we want commands that work
-on (existing) @code{Voice}s to remain working. This is achieved by
-giving the new context an alias @code{Voice},
+Since it is similar to the @code{Voice} context, we want commands that
+work in (existing) @code{Voice} contexts to continue working. This is
+achieved by giving the new context an alias of @code{Voice},
@example
\alias Voice
@end example
The context will print notes and instructive texts, so we need to add
-the engravers which provide this functionality,
+the engravers which provide this functionality, plus the engraver which
+groups notes, stems and rests which occur at the same musical moment
+into columns,
@example
\consists "Note_heads_engraver"
\consists "Text_engraver"
+\consists "Rhythmic_column_engraver"
@end example
-but we only need this on the center line,
+The note heads should all be placed on the center line,
@example
\consists "Pitch_squash_engraver"
squashedPosition = #0
@end example
-The @rinternals{Pitch_squash_engraver} modifies note heads (created
-by @rinternals{Note_heads_engraver}) and sets their vertical
-position to the value of @code{squashedPosition}, in this case@tie{}@code{0},
-the center line.
+The @code{Pitch_squash_engraver} modifies note heads (created
+by the @code{Note_heads_engraver}) and sets their vertical
+position to the value of @code{squashedPosition}, in this
+case@tie{}@code{0}, the center line.
The notes look like a slash, and have no stem,
@example
\override NoteHead.style = #'slash
\override Stem.transparent = ##t
-\override Flag.transparent = ##t
@end example
All these plug-ins have to cooperate, and this is achieved with a
\type "Engraver_group"
\consists "Note_heads_engraver"
\consists "Text_engraver"
+ \consists "Rhythmic_column_engraver"
\consists "Pitch_squash_engraver"
squashedPosition = #0
\override NoteHead.style = #'slash
\override Stem.transparent = ##t
- \override Flag.transparent = ##t
\alias Voice
@}
@end example
@funindex \accepts
-Contexts form hierarchies. We want to hang the @code{ImproVoice}
-under @code{Staff}, just like normal @code{Voice}s. Therefore, we
-modify the @code{Staff} definition with the @code{\accepts}
-command,
+Contexts form hierarchies. We want to place the @code{ImproVoice}
+context within the @code{Staff} context, just like normal @code{Voice}
+contexts. Therefore, we modify the @code{Staff} definition with the
+@code{\accepts} command,
@example
\context @{
@}
@end example
+@seealso
+
+Internals Reference:
+@rinternals{Engraver_group},
+@rinternals{Note_heads_engraver},
+@rinternals{Text_engraver},
+@rinternals{Rhythmic_column_engraver},
+@rinternals{Pitch_squash_engraver}.
+
@node Context layout order
@subsection Context layout order
with the @code{VaticanaVoice} context substituted for the @code{Voice}
context in the @qq{accepts} list.
-Note that a context will be silently created implicitly if a command
-is encountered when there is no suitable context available to
-contain it. This can give rise to unexpected new staves or scores.
+@cindex contexts, implicit
+@cindex implicit contexts
+@funindex \defaultchild
+
+Note that a context will be silently created implicitly if a
+command is encountered when there is no suitable context available
+to contain it.
+
+Within a context definition, the type of subcontext to be
+implicitly created is specified using @code{\defaultchild}. A
+number of music events require a @samp{Bottom} context: when such
+an event is encountered, subcontexts are created recursively until
+reaching a context with no @samp{defaultchild} setting.
+
+Implicit context creation can at times give rise to unexpected new
+staves or scores. Using @code{\new} to create contexts explicitly
+avoids those problems.
@cindex alignAboveContext
@cindex alignBelowContext
Internals Reference:
@rinternals{Tunable context properties}.
-@cindex grob properties
-@cindex properties, grob
-@funindex \override
-
@node The override command
@subsection The @code{\override} command
+@cindex grob properties
+@cindex properties, grob
+@funindex \override
+
There is a special type of context property: the grob
description. Grob descriptions are named in @code{StudlyCaps}
(starting with capital letters). They contain the
properties.
@code{fontSize} is a special property: it is equivalent to
-entering @code{\override ... #'font-size} for all pertinent
+entering @code{\override @dots{} #'font-size} for all pertinent
objects. Since this is a common change, the special
property (modified with @code{\set}) was created.
@item @code{KeySignature} @tab @code{Staff} @tab @code{begin-of-line-visible}
@c omit LeftEdge until it can be explained -td
@c @item @code{LeftEdge} @tab @code{Score} @tab @code{center-invisible}
-@item @code{OctavateEight} @tab @code{Staff} @tab @code{begin-of-line-visible}
+@item @code{ClefModifier} @tab @code{Staff} @tab @code{begin-of-line-visible}
@item @code{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
@item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
f4 g a b
f4 g a b
% Remove bar line at the end of the current line
-\once \override Score.BarLine.break-visibility = #'#(#f #t #t)
+\once \override Score.BarLine.break-visibility = ##(#f #t #t)
\break
f4 g a b
f4 g a b
suppressed. Use begin-of line-invisible to print and
all-invisible to suppress.
@item Key signature -- see below
-@item OctavateEight -- see below
+@item ClefModifier -- see below
@end itemize
@node Special considerations
@c TODO Add example
-@subsubsubheading Octavated clefs
+@subsubsubheading Transposed clefs
-@cindex octavated clefs, visibility of
-@cindex visibility of octavated clefs
-@cindex clefs, visibility of octavation
+@cindex transposed clefs, visibility of
+@cindex visibility of transposed clefs
+@cindex clefs, visibility of transposition
-The small octavation symbol on octavated clefs is produced by the
-@code{OctavateEight} layout object. Its visibility is automatically
+The small transposition symbol on transposed clefs is produced by the
+@code{ClefModifier} layout object. Its visibility is automatically
inherited from the @code{Clef} object, so it is not necessary to apply
-any required @code{break-visibility} overrides to the @code{OctavateEight}
-layout objects to suppress octavation symbols for invisible clefs.
+any required @code{break-visibility} overrides to the @code{ClefModifier}
+layout objects to suppress transposition symbols for invisible clefs.
For explicit clef changes, the @code{explicitClefVisibility}
-property controls both the clef symbol and any octavation symbol
+property controls both the clef symbol and any transposition symbol
associated with it.
@seealso
@code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
@code{time-signature}.
-By default, rehearsal marks and bar numbers will be horizontally
-centered above the object:
+Each type of object has its own default reference point, to which
+rehearsal marks are aligned:
@lilypond[verbatim,quote,relative=1]
-% The rehearsal mark will be centered above the Clef
+% The rehearsal mark will be aligned to right edge of the Clef
\override Score.RehearsalMark.break-align-symbols = #'(clef)
\key a \major
\clef treble
line would be.
@lilypond[verbatim,quote,relative=1]
-% The rehearsal mark will be centered above the Key Signature
+% The rehearsal mark will be aligned to the right edge of the Key Signature
\override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
\key a \major
\clef treble
\mark "↓"
e1
-% The rehearsal mark will be centered above the Clef
+% The rehearsal mark will be aligned to the right edge of the Clef
\set Staff.explicitKeySignatureVisibility = #all-invisible
\override Score.RehearsalMark.break-align-symbols = #'(key-signature clef)
\key a \major
multiple staves, this setting should be done for all the staves.
@lilypond[verbatim,quote,relative=1]
-% The RehearsalMark will be centered above the Key Signature
+% The RehearsalMark will be aligned with the right edge of the Key Signature
\override Score.RehearsalMark.break-align-symbols = #'(key-signature)
\key a \major
\clef treble
\time 4/4
\mark "↓"
e1
-% The RehearsalMark will be aligned with the left edge of the Key Signature
-\once \override Score.KeySignature.break-align-anchor-alignment = #LEFT
+% The RehearsalMark will be centered above the Key Signature
+\once \override Score.KeySignature.break-align-anchor-alignment = #CENTER
\mark "↓"
\key a \major
e1
-% The RehearsalMark will be aligned with the right edge of the Key Signature
-\once \override Score.KeySignature.break-align-anchor-alignment = #RIGHT
+% The RehearsalMark will be aligned with the left edge of the Key Signature
+\once \override Score.KeySignature.break-align-anchor-alignment = #LEFT
\key a \major
\mark "↓"
e1
Internals Reference:
@rinternals{TieColumn}.
+
+@node Unpure-pure containers
+@subsection Unpure-pure containers
+
@cindex Scheme, pure containers
@cindex Scheme, unpure containers
@cindex pure containers, Scheme
@cindex unpure containers, Scheme
@cindex horizontal spacing, overriding
-
-@node Unpure-pure containers
-@subsection Unpure-pure containers
-
Unpure-pure containers are useful for overriding @emph{Y-axis} spacing
calculations - specifically @code{Y-offset} and @code{Y-extent} - with a
Scheme function instead of a literal (i.e. a number or pair).
projects / lilypond.git / blobdiff