change that default layout. The layout is controlled through a large
number of proverbial ``knobs and switches.'' This chapter does not
list each and every knob. Rather, it outlines what groups of controls
-are available, and how to tune them.
+are available, and it explains how to lookup which knob to use for a
+certain effect.
-Which controls are available for tuning is described in a separate
+The controls are available for tuning are described in a separate
document, the @internalsref{Program reference} manual. This manual
lists all different variables, functions and options available in
LilyPond. It is available as a HTML document, which is available
@uref{http://lilypond.org/doc/Documentation/user/out-www/lilypond-internals/,on-line},
but is also included with the LilyPond documentation package.
-There are X areas where the default settings may be changed:
+There are three areas where the default settings may be changed:
@itemize @bullet
@item Output: changing the appearance of individual
@menu
* Scheme tutorial::
-* Context ::
-* Fine tuning layout::
+* Interpretation contexts::
* Tuning output::
+* Fonts::
* Text markup::
* Global layout::
-* Interpretation context::
* Output details::
@end menu
@example
##t ##f
- #1 #1.5
+ #1 #-1.5
#"this is a string"
#"this
is
@end example
-@node Context
-@section Context
+@node Interpretation contexts
+@section Interpretation contexts
When music is printed, a lot of things notation elements must be added
to the input, which is often bare bones. For example, compare 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 program remembers where measure boundaries are, and what pitches
-need explicit accidentals.
+need explicit accidentals.
-This information can be present on several levels. For example, the
-effect of an accidental is limited to a single stave, while a bar line
-must be synchronized across the entire score. To match this
-hierarchy, LilyPond's interpretation step is hierarchical. There are
-interpretation contexts, like @context{Voice}, Staff and Score, and each level
-can maintain its own properties.
+This is contextual information. and it can be present on several
+levels. For example, the effect of an accidental is limited to a
+single stave, while a bar line must be synchronized across the entire
+score. To match this hierarchy, LilyPond's interpretation step is
+hierarchical. There are interpretation contexts, like
+@context{Voice}, Staff and Score, and each level can maintain its own
+properties.
Full description of all available contexts is in the program
reference, see
Translation @arrow{} Context.
@end ifnothtml
+[TODO: describe propagation]
+
+
@menu
* Creating contexts::
* Changing context properties on the fly ::
* Modifying context plug-ins::
-* Defining context defaults ::
-* which properties to change::
+* Layout tunings within contexts::
+* Changing context default settings::
+* Defining new contexts::
+* Which properties to change::
@end menu
@node Creating contexts
@subsection Creating contexts
-For simple scores, the correct contexts are created automatically. For
-more complex scores, it is necessary to instantiate them by hand.
-There are three commands to do this.
+For scores with only one voice and one staff, correct contexts are
+created automatically. For more complex scores, it is necessary to
+instantiate them by hand. There are three commands to do this.
The easiest command is @code{\new}, and it also the quickest to type.
It is prepended to a music expression, for example
>>
@end lilypond
-
-The @code{\context} command also directs a music expression to a
-context object, but gives the context an extra name. The syntax is
+Like @code{\new}, the @code{\context} command also directs a music
+expression to a context object, but gives the context an extra name. The
+syntax is
@example
\context @var{type} = @var{id} @var{music}
music = \notes { c4 c4 }
arts = \notes { s4-. s4-> }
\score {
- << \new Staff \context Voice = "A" \music
+ \notes \relative c'' << \new Staff \context Voice = "A" \music
\context Voice = "A" \arts
>>
}
This is achieved by inserting the @code{\set} command in the music,
@quotation
- @code{\set }[@var{context}]@code{.}@var{prop}@code{ = #}@var{value}
+ @code{\set } @var{context}@code{.}@var{prop}@code{ = #}@var{value}
@end quotation
For example,
multi rests are condensed. The value assigned is a Scheme object. In
this case, it is @code{#t}, the boolean True value.
-If the @var{context} argument is left out, then the current
-bottom-most context (typically ChordNames, @context{Voice} or Lyrics)
-is used. In this example,
+If the @var{context} argument is left out, then the current bottom-most
+context (typically @context{ChordNames}, @context{Voice} or
+@context{Lyrics}) is used. In this example,
@lilypond[verbatim,relative=2]
c8 c c c
@internalsref{Voice} is used.
Contexts are hierarchical, so if a bigger context was specified, for
-example @code{Staff}, then the change would also apply to all
+example @context{Staff}, then the change would also apply to all
@context{Voice}s in the current stave. The change is applied
`on-the-fly', during the music, so that the setting only affects the
second group of eighth notes.
There is also an @code{\unset} command,
@quotation
- @code{\set }[@var{context}]@code{.}@var{prop}
+ @code{\set }@var{context}@code{.}@var{prop}
@end quotation
@noindent
@noindent
the current @context{Voice} does not have the property, and the
-definition at @context{Staff} level remains intact.
+definition at @context{Staff} level remains intact. Like @code{\set},
+the @var{context} argument does not have to be specified for a bottom
+context.
Settings that should only apply to a single time-step can be entered
easily with @code{\once}, for example in
c4
@end lilypond
-the property @code{fontSize} is unset automatically after the third
+the property @code{fontSize} is unset automatically after the second
note.
A full description of all available context properties is in the
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 them like this,
+modifying it like this,
@example
\new @var{context} \with @{
@end lilypond
In the second stave there are no time signature or clef symbols. This
-is a rather crude method of making objects disappear, it will affect
-the entire staff. More sophisticated methods are shown in (TODO).
+is a rather crude method of making objects disappear, it will affect the
+entire staff. The spacing will be adversely influenced too. More
+sophisticated methods of blanking objects are shown in (TODO).
The next example shows a practical application. Bar lines and time
signatures are normally synchronized across the score. This is done
\time 2/4
c4 c c c c c
}
- >>
+>>
+@end lilypond
+
+
+@node Layout tunings within contexts
+@subsection Layout tunings within contexts
+
+Each context is responsible for creating certain types of graphical
+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
+ \override @var{context}.@var{name}@code{ #'}@var{property} = #@var{value}
+@end example
+
+Here @var{name} is the name of a graphical object, like @code{Stem} or
+@code{NoteHead}. @var{property} is an internal variable of the
+formatting system (`grob property' or `layout property'). It is a
+symbol, so it must be quoted. The subsection refTODO explains what to
+fill in for @var{name}, @var{property} and @var{value}. Here we only
+discuss functionality of this command.
+
+The command
+
+@verbatim
+ \override Staff.Stem #'thickness = #4.0
+@end verbatim
+
+@noindent
+makes stems thicker (the default is 1.3, with staff line thickness as a
+unit). Since the command specifies @context{Staff} as context, it only
+applies to the current staff. Other staves will keep their normal
+appearance. Here we see the command in action:
+
+@lilypond[verbatim,relative=2]
+ c4
+ \override Staff.Stem #'thickness = #4.0
+ c4
+ c4
+ c4
+@end lilypond
+
+The @code{\override} command is executed during the interpreting phase,
+and changes the definition of the @code{Stem} within
+@context{Staff}. After the command all stems are thickened.
+
+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 only one timestep
+
+@lilypond[verbatim,relative=2]
+ c4
+ \once \override Stem #'thickness = #4.0
+ 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 that
+the object is created. In this example,
+
+
+@lilypond[verbatim,relative=2]
+ \override Slur #'thickness = #3.0
+ c8[( c
+ \override Beam #'thickness = #0.6
+ c8 c])
+@end lilypond
+
+@noindent
+the slur is fatter and the beam is not. This is because the command for
+@code{Beam} comes after the Beam is started. Therefore it has no effect.
+
+Analogous to @code{\unset}, the @code{\revert} command for a context
+undoes a @code{\override} command; like with @code{\unset}, it only
+affects settings that were made in the same context. In other words, the
+@code{\revert} in the next example does not do anything.
+
+@verbatim
+ \override Voice.Stem #'thickness = #4.0
+ \revert Staff.Stem #'thickness
+@end verbatim
+
+
+
+
+@seealso
+
+Internals: @internalsref{OverrideProperty}, @internalsref{RevertProperty},
+@internalsref{PropertySet}, @internalsref{All-backend-properties}, and
+@internalsref{All-layout-objects}.
+
+
+@refbugs
+
+The back-end is not very strict in type-checking object properties.
+Cyclic references in Scheme values for properties can cause hangs
+and/or crashes.
+
+
+@node Changing context default settings
+@subsection Changing context default settings
+
+The adjustments of the previous chapters can also be entered separate
+from the music, in the @code{\paper} block,
+
+@example
+ \paper @{
+ @dots{}
+ \context @{
+ \StaffContext
+
+ \set fontSize = #-2
+ \override Stem #'thickness
+ \remove "Time_signature_engraver"
+ @}
+ @}
+@end example
+
+This
+@example
+ \StaffContext
+@end example
+
+@noindent
+takes the existing definition @context{Staff} from the identifier
+@code{StaffContext}. This works analogously other contexts, so the
+existing definition of @code{Voice} is in
+@code{\VoiceContext}.
+
+The statements
+@example
+ \set fontSize = #-2
+ \override Stem #'thickness
+ \remove "Time_signature_engraver"
+@end example
+
+@noindent
+affect all staves in the score.
+
+The @code{\set} keyword is optional within the @code{\paper} block, so
+
+@example
+ fontSize = #-2
+@end example
+
+@noindent
+will also work.
+
+
+
+@refbugs
+
+It is not possible to collect changes in a variable, and apply them to
+one @code{\context} definition by referencing that variable.
+
+
+@node Defining new contexts
+@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.
+
+The next example shows how to build a different type of
+@context{Voice} context from scratch. It will be similar to
+@code{Voice}, but print centered slash noteheads only. It can be used
+to indicate improvisation in Jazz pieces,
+
+@lilypond[raggedright]
+ \paper { \context {
+ \name ImproVoice
+ \type "Engraver_group_engraver"
+ \consists "Note_heads_engraver"
+ \consists "Text_engraver"
+ \consists Pitch_squash_engraver
+ squashedPosition = #0
+ \override NoteHead #'style = #'slash
+ \override Stem #'transparent = ##t
+ \alias Voice
+ }
+ \context { \StaffContext
+ \accepts "ImproVoice"
+ }}
+ \score { \notes \relative c'' {
+ a4 d8 bes8 \new ImproVoice { c4^"ad lib" c
+ c4 c^"undress" c_"while playing :)" c }
+ a1
+ }}
@end lilypond
-@node Defining context defaults
-@subsection Defining context defaults
+These settings are again done within a @code{\context} block inside a
+@code{\paper} block,
+
+@example
+ \paper @{
+ \context @{
+ @dots{}
+ @}
+ @}
+@end example
+
+In the following discussion, the example input shown should go on the
+@dots{} of the previous fragment.
+
+First, name the context gets a name. Instead of @context{Voice} it
+will be called @context{ImproVoice},
+
+@verbatim
+ \name ImproVoice
+@end verbatim
+
+Since it is similar to the @context{Voice}, we want commands that work
+on (existing) @context{Voice}s to remain working. This is achieved by
+giving the new context an alias @context{Voice},
+
+@verbatim
+ \alias Voice
+@end verbatim
+
+The context will print notes, and instructive texts
+
+@verbatim
+ \consists Note_heads_engraver
+ \consists Text_engraver
+@end verbatim
+
+but only on the center line,
+
+@verbatim
+ \consists Pitch_squash_engraver
+ squashedPosition = #0
+@end verbatim
+
+The @internalsref{Pitch_squash_engraver} modifies note heads (created
+by @internalsref{Note_heads_engraver}) and sets their vertical
+position to the value of @code{squashedPosition}, in this case
+@code{0}, the center line.
+
+The notes look like a slash, without a stem,
+
+@verbatim
+ \override NoteHead #'style = #'slash
+ \override Stem #'transparent = ##t
+@end verbatim
+
+
+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_engraver},
+
+@example
+ \type "Engraver_group_engraver"
+@end example
-Context properties can be set as defaults, within the
-@code{\paper} block. For example,
+Put together, we get
@verbatim
-\paper {
\context {
- \ScoreContext
- skipBars = ##t
+ \name ImproVoice
+ \type "Engraver_group_engraver"
+ \consists "Note_heads_engraver"
+ \consists "Text_script_engraver"
+ \consists Pitch_squash_engraver
+ squashedPosition = #0
+ \override NoteHead #'style = #'slash
+ \override Stem #'transparent = ##t
+ \alias Voice
}
-}
@end verbatim
-@noindent
-will set skipBars default
+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 when reusing existing context definitions. }
+
+
+
+@verbatim
+ \context {
+ \StaffContext
+ \accepts ImproVoice
+ }
+@end verbatim
+
+Putting both into a @code{\paper} block, like
+
+@example
+ \paper @{
+ \context @{
+ \name ImproVoice
+ @dots{}
+ @}
+ \context @{
+ \StaffContext
+ \accepts "ImproVoice"
+ @}
+@}
+@end example
-When This score-wide
+Then the output at the start of this subsection can be entered as
+@verbatim
+\score {
+ \notes \relative c'' {
+ a4 d8 bes8
+ \new ImproVoice {
+ c4^"ad lib" c
+ c4 c^"undress"
+ c c_"while playing :)"
+ }
+ a1
+ }
+}
+@end verbatim
+
-@node which properties to change
-@subsection which properties to change
+
+@node Which properties to change
+@subsection Which properties to change
There are many different properties. Not all of them are listed in
examples.
-@node Fine tuning layout
-@section Fine tuning layout
+@node Tuning output
+@section Tuning output
-Sometimes it is necessary to change music layout by hand. When music
-is formatted, layout objects are created for each symbol. For
-example, every clef and every note head is represented by a layout
-object. These layout objects also carry variables, which we call
-@emph{layout properties}. By changing these variables from their
-values, we can alter the look of a formatted score:
+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 at in more detail how to use the command in practice.
+First, we will give a a few versatile commands, which are sufficient
+for many situations. The next section will discuss general use of
+@code{\override}.
-@lilypond[verbatim,relative]
- c4
- \override Stem #'thickness = #3.0
- c4 c4 c4
-@end lilypond
-@noindent
-In the example shown here, the layout property @code{thickness} (a
-symbol) is set to 3 in the @code{Stem} layout objects of the current
-As a result, the notes following @code{\override} have thicker
-stems.
-For the most part, a manual override is needed only on a case by
-case basis and not for all subsequent instances of the altered
-property. To accomplish this, simply prefix @code{\once} to the
-@code{\override} statement and the override will apply only once,
-immediately reverting to its default setting, i.e.
+-nmost adjustments simply
+
+
+
+The commands changes
+
+
+There are situations where default layout decisions are not
+sufficient. In this section we discuss ways to override these
+defaults.
+
+Formatting is internally done by manipulating so called objects
+(graphic objects). Each object carries with it a set of properties
+(object or layout properties) specific to that object. For example, a
+stem object has properties that specify its direction, length and
+thickness.
+
+The most direct way of tuning the output is by altering the values of
+these properties. There are two ways of doing that: first, you can
+temporarily change the definition of one type of object, thus
+affecting a whole set of objects. Second, you can select one specific
+object, and set a layout property in that object.
+Do not confuse layout properties with translation
+properties. Translation properties always use a mixed caps style
+naming, and are manipulated using @code{\set} and @code{\unset}:
@example
- \once \override Stem #'thickness = #3.0
+ \set Context.propertyName = @var{value}
@end example
-@lilypond[relative]
- c4
- \once \override Stem #'thickness = #3.0
- c4 c4 c4
-@end lilypond
+Layout properties are use Scheme style variable naming, i.e. lower
+case words separated with dashes. They are symbols, and should always
+be quoted using @code{#'}. For example, this could be an imaginary
+layout property name:
+@example
+ #'layout-property-name
+@end example
+
+
+@menu
+* Common tweaks::
+* Constructing a tweak::
+* Navigating the program reference::
+* Layout interfaces::
+* Determining the grob property::
+@end menu
+
+
+
+@node Common tweaks
+@subsection Common tweaks
-@noindent
Some overrides are so common that predefined commands are provided as
a short cut. For example, @code{\slurUp} and @code{\stemDown}. These
commands are described in
@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, and blanking a stem
in that voice, the tie appears to cross voices:
-@lilypond[fragment,relative=1,verbatim]
- c4 << {
+@lilypond[fragment,relative=2,verbatim]
+ << {
\once \override Stem #'transparent = ##t
- b8~ b8
+ b8~ b8\noBeam
} \\ {
b[ g8]
} >>
@end itemize
-More specific overrides are also possible. The notation manual
-discusses in depth how to figure out these statements for yourself, in
-@ref{Tuning output}.
-
-
-
+More specific overrides are also possible. The following section
+discusses in depth how to figure out these statements for yourself.
-@node Tuning output
-@section Tuning output
-
-There are situations where default layout decisions are not
-sufficient. In this section we discuss ways to override these
-defaults.
-Formatting is internally done by manipulating so called objects
-(graphic objects). Each object carries with it a set of properties
-(object or layout properties) specific to that object. For example, a
-stem object has properties that specify its direction, length and
-thickness.
+@node Constructing a tweak
+@subsection Constructing a tweak
-The most direct way of tuning the output is by altering the values of
-these properties. There are two ways of doing that: first, you can
-temporarily change the definition of one type of object, thus
-affecting a whole set of objects. Second, you can select one specific
-object, and set a layout property in that object.
+The general procedure of changing output, that is, entering
+a command like
-Do not confuse layout properties with translation
-properties. Translation properties always use a mixed caps style
-naming, and are manipulated using @code{\set} and @code{\unset}:
@example
- \set Context.propertyName = @var{value}
+ \override Voice.Stem #'thickness = #3.0
@end example
-Layout properties are use Scheme style variable naming, i.e. lower
-case words separated with dashes. They are symbols, and should always
-be quoted using @code{#'}. For example, this could be an imaginary
-layout property name:
-@example
- #'layout-property-name
-@end example
+@noindent
+means that we have to 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
-@menu
-* Tuning objects::
-* Constructing a tweak::
-* Selecting font sizes::
-* Font selection::
-@end menu
+@cindex internal documentation
+@cindex finding graphical objects
+@cindex graphical object descriptions
+@cindex tweaking
+@cindex @code{\override}
+@cindex @code{\set}
+@cindex internal documentation
+We demonstrate how to glean this information from the notation manual
+and the program reference.
-@node Tuning objects
-@subsection Tuning objects
+The program reference is a set of HTML pages, which is part of the
+documentation package. On Unix systems, it is is typically in
+@file{/usr/share/doc/lilypond}, if you have them, it is best to
+bookmark them in your webbrowser, because you will need them. They
+are also available on the web: go to the
+@uref{http://lilypond.org,LilyPond website}, click ``Documentation'',
+select the correct version, and then click ``Program reference.''
-@cindex object description
+If you have them, use the local HTML files. They will load faster,
+and they are exactly matched to LilyPond version installed.
+
-The definition of an object is a list of default object
-properties. For example, the definition of the Stem object (available
-in @file{scm/define-grobs.scm}), includes the following definitions
-for @internalsref{Stem}:
-@example
- (thickness . 1.3)
- (beamed-lengths . (3.5 3.5 3.5 4.5 5.0))
- (Y-extent-callback . ,Stem::height)
- @var{...}
-@end example
+@c [TODO: revise for new site.]
+@node Navigating the program reference
+@subsection Navigating the program reference
-Adding variables on top of this existing definition overrides the
-system default, and alters the resulting appearance of the layout
-object.
+Suppose we want to move the fingering indication in the fragment
+below:
+@lilypond[relative=2,verbatim]
+c-2
+\stemUp
+f
+@end lilypond
+If you visit the documentation of @code{Fingering} (in @ref{Fingering
+instructions}), you will notice that there is written:
-Changing a variable for only one object is commonly achieved with
-@code{\once}:
+@quotation
+@seealso
-@example
-\once \override @var{context}.@var{objectname}
- @var{symbol} = @var{value}
-@end example
-Here @var{symbol} is a Scheme expression of symbol type, @var{context}
-and @var{objectname} is a string and @var{value} is a Scheme expression.
-This command applies a setting only during one moment in the score.
+Program reference: @internalsref{FingerEvent} and @internalsref{Fingering}.
-In the following example, only one @internalsref{Stem} object is
-changed from its original setting:
+@end quotation
-@lilypond[verbatim,fragment,relative=1]
- c4
- \once \override Voice.Stem #'thickness = #4
- c4
- c4
-@end lilypond
-@cindex @code{\once}
+This fragments points to two parts of the program reference: a page
+on @code{FingerEvent} and @code{Fingering}.
-For changing more objects, the same command, without @code{\once} can
-be used:
-@example
-\override @var{context}.@var{objectname} @var{symbol} = @var{value}
-@end example
-This command adds @code{@var{symbol} = @var{value}} to the definition
-of @var{objectname} in the context @var{context}, and this definition
-stays in place until it is removed.
+The page on @code{FingerEvent} describes the properties of the music
+expression for the input @code{-2}. The page contains many links
+forward. For example, it says
-An existing definition may be removed by the following command:
-@c
-@example
-\property @var{context}.@var{objectname} \revert @var{symbol}
-@end example
-@c
+@quotation
+ Accepted by: @internalsref{Fingering_engraver},
+@end quotation
-Some examples:
-@lilypond[verbatim]
-c'4 \override Stem #'thickness = #4.0
-c'4
-c'4 \revert Stem #'thickness
-c'4
-@end lilypond
+@noindent
+That link brings us to the documentation for the Engraver, the
+plug-in, which says
+@quotation
+ This engraver creates the following layout objects: @internalsref{Fingering}.
+@end quotation
+In other words, once the @code{FingerEvent}s are interpreted, the
+@code{Fingering_engraver} plug-in will process them.
+The @code{Fingering_engraver} is also listed to create
+@internalsref{Fingering} objects,
-Reverting a setting which was not set in the first place has no
-effect.
+ Lo and behold, that 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:
-@seealso
+@itemize @bullet
-Internals: @internalsref{OverrideProperty}, @internalsref{RevertProperty},
-@internalsref{PropertySet}, @internalsref{All-backend-properties}, and
-@internalsref{All-layout-objects}.
+@item @internalsref{Fingering}:
+ @internalsref{Fingering} objects are created by:
+ @b{@internalsref{Fingering_engraver}}
+@item @internalsref{Fingering_engraver}:
+Music types accepted: @b{@internalsref{fingering-event}}
+@item @internalsref{fingering-event}:
+Music event type @code{fingering-event} is in Music objects of type
+@b{@internalsref{FingerEvent}}
+@end itemize
-@refbugs
+This path goes against the flow of information in the program: it
+starts from the output, and ends at the input event.
-The back-end is not very strict in type-checking object properties.
-Cyclic references in Scheme values for properties can cause hangs
-and/or crashes.
+The program reference can also be browsed like a normal document. It
+contains a chapter on @internalsref{Music definitions}, on
+@internalsref{Translation}, and the @internalsref{Backend}. Every
+ chapter lists all the definitions used, and all properties that may
+ be tuned.
+
+@node Layout interfaces
+@subsection Layout interfaces
-@node Constructing a tweak
-@subsection Constructing a tweak
+@internalsref{Fingering} is a layout object. Such an object is a
+symbol within the score. It has properties, which store numbers (like
+thicknesses and directions), but also pointers to related objects.
+A layout object is also called @emph{grob},
+@cindex grob
+which is short for Graphical Object.
-@cindex internal documentation
-@cindex finding graphical objects
-@cindex graphical object descriptions
-@cindex tweaking
-@cindex @code{\override}
-@cindex @code{\set}
-@cindex internal documentation
+The page for @code{Fingering} lists the definitions for the
+@code{Fingering} object. For example, the page says
+@quotation
+ @code{padding} (dimension, in staff space):
+
+ @code{0.6}
+@end quotation
+which means that the number will be kept at a distance of at least 0.6
+of the note head.
-Three pieces of information are required to use @code{\override} and
-@code{\set}: the name of the layout object, the context and the name
-of the property. We demonstrate how to glean this information from
-the notation manual and the program reference.
-The generated documentation is a set of HTML pages which should be
-included if you installed a binary distribution, typically in
-@file{/usr/share/doc/lilypond}. They are also available on the web:
-go to the @uref{http://lilypond.org,LilyPond website}, click
-``Documentation'', select the correct version, and then click
-``Program reference.'' It is advisable to bookmark the local HTML
-files. They will load faster than the ones on the web and matches the
-version of LilyPond you are using.
-
+Each layout object may have several functions as a notational or
+typographical element. For example, the Fingering object
+has the following aspects
+@itemize @bullet
+@item Its size is independent of the horizontal spacing, unlike slurs or beams
-@c [TODO: revise for new site.]
+@item It is a piece of text. Granted, it's usually a very short text.
-Suppose we want to move the fingering indication in the fragment
-below:
+@item That piece of text is set in a font, unlike slurs or beams.
+@item Horizontally, the center of the symbol should be aligned to the
+center of the notehead
+@item Vertically, the symbol is placed next to the note and the staff.
-@lilypond[relative=2,verbatim]
-c-2
-\stemUp
-f
-@end lilypond
+@item The
+ vertical position is also coordinated with other super and subscript
+symbols
+@end itemize
-If you visit the documentation of @code{Fingering} (in @ref{Fingering
-instructions}), you will notice that there is written:
+Each of these aspects is captured in a so-called @emph{interface},
+which are listed on the @internalsref{Fingering} page at the bottom
@quotation
-@seealso
+This object supports the following interfaces:
+@internalsref{item-interface},
+@internalsref{self-alignment-interface},
+@internalsref{side-position-interface}, @internalsref{text-interface},
+@internalsref{text-script-interface}, @internalsref{font-interface},
+@internalsref{finger-interface} and @internalsref{grob-interface}
+@end quotation
-Internals: @internalsref{FingerEvent} and @internalsref{Fingering}.
+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.
-@end quotation
+We have been talking of `the' @code{Fingering} object, but actually it
+does not amount to much. The initialization file
+@file{scm/define-grobs.scm} shows the soul of the `object',
-@separate
+@verbatim
+ (Fingering
+ . (
+ (print-function . ,Text_item::print)
+ (padding . 0.6)
+ (staff-padding . 0.6)
+ (self-alignment-X . 0)
+ (self-alignment-Y . 0)
+ (script-priority . 100)
+ (font-encoding . number)
+ (font-size . -5)
+ (meta . ((interfaces . (finger-interface font-interface
+ text-script-interface text-interface
+ side-position-interface self-alignment-interface
+ item-interface))))
+ ))
+@end verbatim
-@noindent
-In other words, the fingerings once entered, are internally stored as
-@code{FingerEvent} music objects. When printed, a @code{Fingering}
-layout object is created for every @code{FingerEvent}.
+as you can see, @code{Fingering} is nothing more than a bunch of
+variable settings, and the webpage is directly generated from this
+definition.
-The Fingering object has a number of different functions, and each of
-those is captured in an interface. The interfaces are listed under
-@internalsref{Fingering} in the program reference.
+@node Determining the grob property
+@subsection Determining the grob property
+Recall that we wanted to change the position of the @b{2} in
+
+@lilypond[relative=2,verbatim]
+c-2
+\stemUp
+f
+@end lilypond
+
+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 by @code{side-position-interface}. The page for this interface says
-The @code{Fingering} object has a fixed size
-(@internalsref{item-interface}), the symbol is a piece of text
-(@internalsref{text-interface}), whose font can be set
-(@internalsref{font-interface}). It is centered horizontally
-(@internalsref{self-alignment-interface}), it is placed vertically
-next to other objects (@internalsref{side-position-interface}), and
-its placement is coordinated with other scripts
-(@internalsref{text-script-interface}). It also has the standard
-@internalsref{grob-interface} (grob stands for Graphical object)
-@cindex grob
-@cindex graphical object
-@cindex layout object
-@cindex object, layout
-with all the variables that come with
-it. Finally, it denotes a fingering instruction, so it has
-@internalsref{finger-interface}.
-
-For the vertical placement, we have to look under
-@code{side-position-interface}:
@quotation
@code{side-position-interface}
Position a victim object (this one) next to other objects (the
- support). In this case, the property @code{direction} signifies where to put the
+ support). The property @code{direction} signifies where to put the
victim object relative to the support (left or right, up or down?)
@end quotation
@item padding
(dimension, in staff space)
- add this much extra space between objects that are next to each
-other. Default value: @code{0.6}
+ add this much extra space between objects that are next to each
+ other.
@end table
@end quotation
fingering. The following command inserts 3 staff spaces of white
between the note and the fingering:
@example
-\once \override Fingering #'padding = #3
+\once \override Fingering #'padding = #3
@end example
Inserting this command before the Fingering object is created,
f
@end lilypond
-The context name @code{Voice} in the example above can be determined
-as follows. In the documentation for @internalsref{Fingering}, it says
+
+In this case, the context for this tweak is @context{Voice}, which
+does not have to be specified for @code{\override}. This fact can
+also be deduced from the program reference, for the page for the
+@internalsref{Fingering_engraver} plug-in says
+
@quotation
-Fingering grobs are created by: @internalsref{Fingering_engraver} @c
+ Fingering_engraver is part of contexts: @dots{} @b{@internalsref{Voice}}
@end quotation
-Clicking @code{Fingering_engraver} shows the documentation of
-the module responsible for interpreting the fingering instructions and
-translating them to a @code{Fingering} object. Such a module is called
-an @emph{engraver}. The documentation of the @code{Fingering_engraver}
-says
-@example
-Fingering_engraver is part of contexts: Voice
-@end example
-so tuning the settings for Fingering should be done with
-@example
- \override Fingering @dots{}
-@end example
-Of course, the tweak may also done in a larger context than
-@code{Voice}, for example, @internalsref{Staff} or
-@internalsref{Score}.
+@node Fonts
+@section Fonts
-@seealso
+@menu
+* Selecting font sizes::
+* Font selection::
+@end menu
-Internals: the program reference also contains alphabetical lists of
-@internalsref{Contexts}, @internalsref{All-layout-objects} and
-@internalsref{Music-expressions}, so you can also find which objects
-to tweak by browsing the internals document.
@node Selecting font sizes
@menu
+* Setting global staff size::
* Vertical spacing::
* Horizontal spacing::
-* Font Size::
* Line breaking::
* Page layout::
@end menu
+@node Setting global staff size
+@subsection Setting global staff size
+
+@cindex font size, setting
+@cindex staff size, setting
+@cindex @code{paper} file
+
+The Feta font provides musical symbols at eight different
+sizes. Each font is tuned for a different staff size: at smaller sizes
+the font gets heavier, to match the relatively heavier staff lines.
+The recommended font sizes are listed in the following table:
+
+@multitable @columnfractions .25 .25 .25 .25
+
+@item @b{font name}
+@tab @b{staff height (pt)}
+@tab @b{staff height (mm)}
+@tab @b{use}
+
+@item feta11
+@tab 11.22
+@tab 3.9
+@tab pocket scores
+
+@item feta13
+@tab 12.60
+@tab 4.4
+@tab
+
+@item feta14
+@tab 14.14
+@tab 5.0
+@tab
+
+@item feta16
+@tab 15.87
+@tab 5.6
+@tab
+
+@item feta18
+@tab 17.82
+@tab 6.3
+@tab song books
+
+@item feta20
+@tab 17.82
+@tab 7.0
+@tab standard parts
+
+@item feta23
+@tab 22.45
+@tab 7.9
+@tab
+
+@item feta20
+@tab 25.2
+@tab 8.9
+@tab
+@c modern rental material ?
+
+@end multitable
+
+These fonts are available in any sizes. The context property
+@code{fontSize} and the layout property @code{staff-space} (in
+@internalsref{StaffSymbol}) can be used to tune size for individual
+staves. The size of individual staves are relative to the global size,
+which can be set in the following manner:
+
+@example
+ #(set-global-staff-size 14)
+@end example
+
+This sets the global default size to 14pt staff height, and scales all
+fonts accordingly.
+
+@seealso
+
+This manual: @ref{Selecting font sizes}.
+
+
+
+@menu
+* Vertical spacing::
+* Horizontal spacing::
+* Line breaking::
+* Page layout::
+@end menu
+
@node Vertical spacing
@subsection Vertical spacing
-@node Font Size
-@subsection Font size
-
-@cindex font size, setting
-@cindex staff size, setting
-@cindex @code{paper} file
-
-The Feta font provides musical symbols at eight different
-sizes. Each font is tuned for a different staff size: at smaller sizes
-the font gets heavier, to match the relatively heavier staff lines.
-The recommended font sizes are listed in the following table:
-
-@multitable @columnfractions .25 .25 .25 .25
-
-@item @b{font name}
-@tab @b{staff height (pt)}
-@tab @b{staff height (mm)}
-@tab @b{use}
-
-@item feta11
-@tab 11.22
-@tab 3.9
-@tab pocket scores
-
-@item feta13
-@tab 12.60
-@tab 4.4
-@tab
-
-@item feta14
-@tab 14.14
-@tab 5.0
-@tab
-
-@item feta16
-@tab 15.87
-@tab 5.6
-@tab
-
-@item feta18
-@tab 17.82
-@tab 6.3
-@tab song books
-
-@item feta20
-@tab 17.82
-@tab 7.0
-@tab standard parts
-
-@item feta23
-@tab 22.45
-@tab 7.9
-@tab
-
-@item feta20
-@tab 25.2
-@tab 8.9
-@tab
-@c modern rental material ?
-
-@end multitable
-
-These fonts are available in any sizes. The context property
-@code{fontSize} and the layout property @code{staff-space} (in
-@internalsref{StaffSymbol}) can be used to tune size for individual
-staves. The size of individual staves are relative to the global size,
-which can be set in the following manner:
-
-@example
- #(set-global-staff-size 14)
-@end example
-
-This sets the global default size to 14pt staff height, and scales all
-fonts accordingly.
-
-@seealso
-
-This manual: @ref{Selecting font sizes}.
-
+@menu
+* Line breaking::
+* Page layout::
+@end menu
@node Line breaking
@subsection Line breaking
@cindex page size
@cindex @code{papersize}
-To change the paper size, use the following Scheme code:
+To change the paper size, there are two commands,
@example
+ #(set-default-paper-size "a4")
\paper@{
#(set-paper-size "a4")
@}
@end example
-
+The second one sets the size of the @code{\paper} block that it's in.
@refcommands
reliably choose page breaks in longer pieces.
-@node Interpretation context
-@section Interpretation context
-
-@menu
-* Context properties::
-* Defining contexts::
-* Changing contexts locally::
-* Engravers and performers::
-* Defining new contexts::
-@end menu
-
-
-Interpretation contexts are objects that only exist during program
-run. During the interpretation phase (when @code{interpreting music}
-is printed on the standard output), the music expression in a
-@code{\score} block is interpreted in time order, the same order in
-which we hear and play the music. During this phase, the interpretation
-context holds the state for the current point within the music, for
-example:
-@itemize @bullet
-@item What notes are playing at this point?
-
-@item What symbols will be printed at this point?
-
-@item What is the current key signature, time signature, point within
-the measure, etc.?
-@end itemize
-
-Contexts are grouped hierarchically: A @internalsref{Voice} context is
-contained in a @internalsref{Staff} context (because a staff can contain
-multiple voices at any point), a @internalsref{Staff} context is contained in
-@internalsref{Score}, @internalsref{StaffGroup}, or
-@internalsref{ChoirStaff} context.
-
-Contexts associated with sheet music output are called @emph{notation
-contexts}, those for sound output are called @emph{performance
-contexts}. The default definitions of the standard notation and
-performance contexts can be found in @file{ly/engraver-init.ly} and
-@file{ly/performer-init.ly}, respectively.
-
-
-
-@node Context properties
-@subsection Context properties
-
-Contexts have properties. These properties are set from the @file{.ly}
-file using the following expression:
-@cindex context properties
-@cindex properties, context
-
-@example
-\set @var{contextname}.@var{propname} = @var{value}
-@end example
-
-@noindent
-Sets the @var{propname} property of the context @var{contextname} to
-the specified Scheme expression @var{value}. Both @var{propname} and
-@var{contextname} are strings, which can often be written unquoted.
-
-@cindex inheriting
-Properties that are set in one context are inherited by all of the
-contained contexts. This means that a property valid for the
-@internalsref{Voice} context can be set in the @internalsref{Score} context
-(for example) and thus take effect in all @internalsref{Voice} contexts.
-
-Properties can be unset using the following statement.
-@example
-\unset @var{contextname}.@var{propname}
-@end example
-
-@cindex properties, unsetting
-@cindex @code{\unset}
-
-@noindent
-This removes the definition of @var{propname} in @var{contextname}. If
-@var{propname} was not defined in @var{contextname} (but was inherited
-from a higher context), then this has no effect.
-
-If @var{contextname} is left out, then it defaults to the current
-``bottom'' context: this is a context like @internalsref{Voice} that
-cannot contain any other contexts.
-
-
-@node Defining contexts
-@subsection Defining contexts
-
-@cindex context definition
-@cindex translator definition
-
-The most common way to create a new context definition is by extending
-an existing one. An existing context from the paper block is copied
-by referencing a context identifier:
-
-@example
-\paper @{
- \context @{
- @var{context-identifier}
- @}
-@}
-@end example
-
-@noindent
-Every predefined context has a standard identifier. For example, the
-@code{Staff} context can be referred to as @code{\StaffContext}.
-
-The context can then be modified by setting or changing properties,
-e.g.
-@example
-\context @{
- \StaffContext
- Stem \set #'thickness = #2.0
- defaultBarType = #"||"
-@}
-@end example
-These assignments happen before interpretation starts, so a property
-command will override any predefined settings.
-
-@cindex engraver
-
-@refbugs
-
-It is not possible to collect multiple property assignments in a
-variable, and apply to one @code{\context} definition by
-referencing that variable.
-
-@node Changing contexts locally
-@subsection Changing contexts locally
-
-
-Extending an existing context can also be done locally. A piece of
-music can be interpreted in a changed context by using the following syntax
-
-@example
- \with @{
- @var{context modifications}
- @}
-@end example
-
-These statements comes between @code{\new} or @code{\context} and the
-music to be interpreted. The @var{context modifications} property
-settings and @code{\remove}, @code{\consists} and @code{\consistsend}
-commands. The syntax is similar to the @code{\context} block.
-
-The following example shows how a staff is created with bigger spaces,
-and without a @code{Clef_engraver}.
-
-@lilypond[relative=1,fragment,verbatim]
-<<
- \new Staff { c4 es4 g2 }
- \new Staff \with {
- \override StaffSymbol #'staff-space = #(magstep 1.5)
- fontSize = #1.5
- \remove "Clef_engraver"
- } {
- c4 es4 g2
- } >>
-@end lilypond
-
-@refbugs
-
-The command @code{\with} has no effect on contexts that already
-exist.
-
-
-@node Engravers and performers
-@subsection Engravers and performers
-
-
-Each context is composed of a number of building blocks, or plug-ins
-called engravers. An engraver is a specialized C++ class that is
-compiled into the executable. Typically, an engraver is responsible
-for one function: the @code{Slur_engraver} creates only @code{Slur}
-objects, and the @code{Skip_event_swallow_translator} only swallows
-(silently gobbles) @code{SkipEvent}s.
-
-
-
-@cindex engraver
-@cindex plug-in
-
-An existing context definition can be changed by adding or removing an
-engraver. The syntax for these operations is
-@example
-\consists @var{engravername}
-\remove @var{engravername}
-@end example
-
-@cindex @code{\consists}
-@cindex @code{\remove}
-
-@noindent
-Here @var{engravername} is a string, the name of an engraver in the
-system. In the following example, the @code{Clef_engraver} is removed
-from the Staff context. The result is a staff without a clef, where
-the middle C is at its default position, the center line:
-
-@lilypond[verbatim,raggedright]
-\score {
- \notes {
- c'4 f'4
- }
- \paper {
- \context {
- \StaffContext
- \remove Clef_engraver
- }
- }
-}
-@end lilypond
-
-A list of all engravers is in the internal documentation,
-see @internalsref{Engravers}.
-
-@node Defining new contexts
-@subsection Defining new contexts
-
-
-It is also possible to define new contexts from scratch. To do this,
-you must define give the new context a name. In the following
-example, a very simple Staff context is created: one that will put
-note heads on a staff symbol.
-
-@example
-\context @{
- \type "Engraver_group_engraver"
- \name "SimpleStaff"
- \alias "Staff"
- \consists "Staff_symbol_engraver"
- \consists "Note_head_engraver"
- \consistsend "Axis_group_engraver"
-@}
-@end example
-
-@noindent
-The argument of @code{\type} is the name for a special engraver that
-handles cooperation between simple engravers such as
-@code{Note_head_engraver} and @code{Staff_symbol_engraver}. This
-should always be @code{Engraver_group_engraver} (unless you are
-defining a Score context from scratch, in which case
-@code{Score_engraver} must be used).
-
-The complete list of context modifiers is the following:
-@itemize @bullet
-@item @code{\alias} @var{alternate-name}:
-This specifies a different name. In the above example,
-@code{\set Staff.X = Y} will also work on @code{SimpleStaff}s.
-
-@item @code{\consistsend} @var{engravername}:
-Analogous to @code{\consists}, but makes sure that
-@var{engravername} is always added to the end of the list of
-engravers.
-
-Engravers that group context objects into axis groups or alignments
-need to be at the end of the list. @code{\consistsend} insures that
-engravers stay at the end even if a user adds or removes engravers.
-
-@item @code{\accepts} @var{contextname}:
-This context can contains @var{contextname} contexts. The first
-@code{\accepts} is created as a default context when events (e.g. notes
-or rests) are encountered.
-
-@item @code{\denies}:
-The opposite of @code{\accepts}.
-
-@item @code{\name} @var{contextname}:
-This sets the type name of the context, e.g. @code{Staff},
-@code{Voice}. If the name is not specified, the translator will not
-do anything.
-@end itemize
-
-@c EOF
-
-
@node Output details
projects / lilypond.git / blobdiff