version that you are working on. See TRANSLATION for details.
@end ignore
-@c \version "2.11.51"
+@c \version "2.11.61"
@node Changing defaults
@chapter Changing defaults
-
-The purpose of LilyPond's design is to provide the finest output
-quality as a default. Nevertheless, it may happen that you need to
+The purpose of LilyPond's design is to provide the finest quality
+output by default. Nevertheless, it may happen that you need to
change this default layout. The layout is controlled through a large
-number of proverbial @q{knobs and switches.} This chapter does not
-list each and every knob. Rather, it outlines what groups of controls
-are available and explains how to lookup which knob to use for a
-particular effect.
-
+number of @q{knobs and switches} collectively called @q{properties}.
+A tutorial introduction to accessing and modifying these properties
+can be found in the Learning Manual, see @rlearning{Tweaking output}.
+This should be read first. This chapter covers similar ground, but
+in a style more appropriate to a reference manual.
@cindex Internals Reference
-The controls available for tuning are described in a separate
-document, the
-@iftex
-Internals Reference manual.
-@end iftex
-@ifnottex
-@ref{Top,Internals Reference,,lilypond-internals}.
-@end ifnottex
-That manual
-lists all different variables, functions and options available in
-LilyPond. It is written as a HTML document, which is available
+The definitive description of the controls available for tuning can
+be found in a separate document: @rinternalsnamed{Top,the Internals
+Reference}. That manual lists all the variables, functions and
+options available in LilyPond. It is written as a HTML document,
+which is available
@c leave the @uref as one long line.
@uref{http://@/lilypond@/.org/@/doc/@/stable/@/Documentation/@/user/@/lilypond@/-internals/,on@/-line},
-but is also included with the LilyPond documentation package.
-
-There are four areas where the default settings may be changed:
-
-@itemize
-@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.
-
-@item
-Page layout: changing the appearance of the spacing, line
-breaks, and page dimensions. These modifications are discussed
-@c in @ref{notation}, and @ref{Spacing issues}.
-@end itemize
+and is also included with the LilyPond documentation package.
Internally, LilyPond uses Scheme (a LISP dialect) to provide
infrastructure. Overriding layout decisions in effect accesses the
* Explaining the Internals Reference::
* Modifying properties::
* Useful concepts and properties::
-* Common properties::
* Advanced tweaks::
-* Discussion of specific tweaks::
@end menu
* Aligning contexts::
@end menu
+@seealso
+
+Learning Manual:
+@rlearning{Contexts and engravers}.
+
+Installed files:
+@file{ly/@/engraver@/-init@/.ly},
+@file{ly/@/performer@/-init@/.ly}.
+
+Snippets:
+@rlsr{Contexts and engravers}.
+
+Internals Reference:
+@rinternals{Contexts},
+@rinternals{Engravers and Performers}.
+
@node Contexts explained
@subsection Contexts explained
-@c FIXME Rethink and rewrite
+@ignore
+@c TODO Rethink and rewrite
>> > > - list of contexts: my *danger unmaintainable*
->> > > alarm just went off. I'm
+>> > > alarm just went off. I'm
I knew it would... And leaving out some of them is perfectly fine
with me.
should be there, and then we could simply list the remaining ones
without
further explanation and with links to the IR.
+@end ignore
+
+@c TODO Improve layout, order and consistency of wording -td
+
+@c TODO Add introduction which explains contexts in generality -td
+
+@c TODO Describe propagation of property values -td
+
+Contexts are arranged heirarchically:
+
+@menu
+* Score - the master of all contexts::
+* Top-level contexts - staff containers::
+* Intermediate-level contexts - staves::
+* Bottom-level contexts - voices::
+@end menu
+
+@node Score - the master of all contexts
+@unnumberedsubsubsec Score - the master of all contexts
+
+This is the top level notation context. No other context can
+contain a Score context. By default the Score context handles
+the administration of time signatures and makes sure that items
+such as clefs, time signatures, and key-signatures are aligned
+across staves.
+
+A Score context is instantiated implicitly when a
+@code{\score @{@dots{}@}} or @code{\layout @{@dots{}@}} block is
+processed, or explicitly when a @code{\new Score} command is
+executed.
+
+@node Top-level contexts - staff containers
+@unnumberedsubsubsec Top-level contexts - staff containers
+
+@strong{@emph{StaffGroup}}
+
+Groups staves while adding a bracket on the left side, grouping
+the staves together. The bar lines of the contained staves are
+connected vertically. StaffGroup only consists of a collection
+of staves, with a bracket in front and spanning bar lines.
+
+@strong{@emph{ChoirStaff}}
+
+Identical to StaffGroup except that the bar lines of the contained
+staves are not connected vertically.
+
+@strong{@emph{GrandStaff}}
+
+A group of staves, with a brace on the left side, grouping
+the staves together. The bar lines of the contained staves are
+connected vertically.
+
+@strong{@emph{PianoStaff}}
+
+@c TODO No longer correct? Check. -td
+Just like GrandStaff but with a forced distance between the
+staves, so cross staff beaming and slurring can be used.
+
+@ignore
+@strong{@emph{InnerStaffGroup}}
+
+TODO -td
+
+@strong{@emph{InnerChoirStaff}}
+
+TODO -td
+
+@end ignore
+
+@node Intermediate-level contexts - staves
+@unnumberedsubsubsec Intermediate-level contexts - staves
+
+@strong{@emph{Staff}}
+
+Handles clefs, bar lines, keys, accidentals. It can contain
+Voice contexts.
+@strong{@emph{RhythmicStaff}}
+
+Like Staff but for printing rhythms. Pitches are ignored;
+the notes are printed on one line.
+
+@strong{@emph{TabStaff}}
+
+Context for generating tablature. By default lays the music
+expression out as a guitar tablature, printed on six lines.
+
+@strong{@emph{DrumStaff}}
+
+Handles typesetting for percussion. Can contain DrumVoice
+
+@strong{@emph{VaticanaStaff}}
+
+Same as Staff, except that it is designed for typesetting
+a piece in gregorian style.
+
+@strong{@emph{MensuralStaff}}
+
+Same as Staff, except that it is designed for typesetting
+a piece in mensural style.
+
+@node Bottom-level contexts - voices
+@unnumberedsubsubsec Bottom-level contexts - voices
+
+Voice-level contexts initialise certain properties and start
+appropriate engravers. Being bottom-level contexts, they cannot
+contain other contexts.
+
+@strong{@emph{Voice}}
+
+Corresponds to a voice on a staff. This context handles the
+conversion of dynamic signs, stems, beams, super- and sub-scripts,
+slurs, ties, and rests. You have to instantiate this explicitly
+if you require multiple voices on the same staff.
+
+@strong{@emph{VaticanaVoice}}
+
+Same as Voice, except that it is designed for typesetting a piece
+in gregorian style.
+
+@strong{@emph{MensuralVoice}}
+
+Same as Voice, with modifications for typesetting a piece in
+mensural style.
+
+@strong{@emph{Lyrics}}
+
+Corresponds to a voice with lyrics. Handles the printing of a
+single line of lyrics.
+
+@strong{@emph{DrumVoice}}
+
+The voice context used in a percussion staff.
+
+@strong{@emph{FiguredBass}}
+
+The context in which BassFigure objects are created from
+input entered in @code{\figuremode} mode.
+
+@strong{@emph{TabVoice}}
+
+The voice context used within a TabStaff context. Usually left to
+be created implicitly.
+
+@strong{@emph{ChordNames}}
+
+Typesets chord names.
+
+@ignore
+TODO
-The Master Of All Contexts
-==========================
-
- * Score
- This is the top level notation context. No other context
-can
- contain a Score context. This context handles the
- administration of time signatures. It also makes sure that
- items such as clefs, time signatures, and key-signatures
-are
- aligned across staves.
- You cannot explicitly instantiate a Score context (since
-it is
- not contained in any other context). It is instantiated
- automatically when an output definition (a \score or
-\layout
- block) is processed.
- (it should also be made clear somewhere what the
-difference is between
- \score and \Score).
-
-Top-level contexts: Staff containers
-====================================
- * StaffGroup
- Groups staves while adding a bracket on the left side,
- grouping the staves together. The bar lines of the
-contained
- staves are connected vertically. StaffGroup only consists
-of a
- collection of staves, with a bracket in front and spanning
-bar
- lines.
- * ChoirStaff
- Identical to StaffGroup except that the contained staves
-are
- not connected vertically.
- * GrandStaff
- A group of staves, with a brace on the left side, grouping
-the
- staves together. The bar lines of the contained staves are
- connected vertically.
- * PianoStaff
- Just like GrandStaff but with a forced distance between
-the
- staves, so cross staff beaming and slurring can be used.
- * DrumStaff
- Handles typesetting for percussion. Can contain DrumVoice
- * InnerStaffGroup
- * InnerChoirStaff
-
-Staff-level contexts
-====================
- * Staff
- Handles clefs, bar lines, keys, accidentals. It can
-contain
- Voice contexts.
- * RhythmicStaff
- Like Staff but for printing rhythms. Pitches are
- ignored; the notes are printed on one line.
- * TabStaff
- Context for generating tablature. By default lays the
-music
- expression out as a guitar tablature, printed on six
-lines.
- * VaticanaStaff
- Same as Staff, except that it is accommodated for
- typesetting a piece in gregorian style.
- * MensuralStaff
- Same as Staff, except that it is accommodated for
- typesetting a piece in mensural style.
-
-Voice-level (bottom) contexts
-=============================
-What is generated by default here? The voice-level contexts
-initiate
-certain properties and start engravers.
-
- * Voice
- Corresponds to a voice on a staff. This context handles
-the
- conversion of dynamic signs, stems, beams, super- and
- subscripts, slurs, ties, and rests.
- You have to instantiate this explicitly if you want to
-have
- multiple voices on the same staff.
- Bottom context.
- * VaticanaVoice
- Same as Voice, except that it is accommodated for
- typesetting a piece in gregorian style.
- * MensuralVoice
- Same as Voice, except that it is accommodated for
- typesetting a piece in mensural style.
- * Lyrics
- Corresponds to a voice with lyrics. Handles the printing
-of a
- single line of lyrics.
- Bottom context.
- * DrumVoice
- A voice on a percussion staff.
- * FiguredBass
-
- * ChordNames
- Typesets chord names. This context is a `bottom' context;
-it
- cannot contain other contexts.
-
-------------------------------
Then the following, which I don't know what to do with:
- * TabVoice
* GregorianTranscriptionVoice
* GregorianTranscriptionStaff
Silently discards all musical information given to this
context.
-
+@end ignore
@node Creating contexts
@subsection Creating contexts
>>
@end lilypond
+@knownissues
+
+Usually the order in which the engravers are specified
+does not matter, but in a few special cases the order
+is important, for example where one engraver writes
+a property and another reads it, or where one engraver
+creates a grob and another must process it. The order in
+which the engravers are specified is the order in which
+they are called to carry out their processing.
+
+The following orderings are important: the
+@code{Bar_engraver} must normally be first, and
+the @code{New_fingering_engraver} must come before
+the @code{Script_column_engraver}. There may be others
+with ordering dependencies.
@node Changing context default settings
@subsection Changing context default settings
The adjustments of the previous subsections (
-@ref{The \set command}, @ref{Modifying context plug-ins}, and
+@ref{The set command}, @ref{Modifying context plug-ins}, and
@ref{Overview of modifying properties}) can also be entered
separately from the music in the @code{\layout} block,
@}
@end example
-TODO: add \with in here.
+@c TODO: add \with in here.
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 @rinternals{Engraver_group},
+This should always be @code{Engraver_group}.
@example
\type "Engraver_group"
@c TODO Better example needed. Ref LM, and expand on it.
@cindex ossia
-@findex alignAboveContext
-@findex alignBelowContext
+@funindex alignAboveContext
+@funindex alignBelowContext
@lilypond[quote,ragged-right]
ossia = { f4 f f f }
}
@end lilypond
+@cindex nested contexts
+@cindex contexts, nested
+
+@funindex \accepts
+@funindex \denies
+
+Contexts like @code{PianoStaff} can contain other contexts
+nested within them. Contexts which are acceptable for nesting
+are defined by the @qq{accepts} list of a context. Contexts
+which are not in this list are placed below the outer context
+in the printed score.
+For example, the @code{PianoStaff} context is defined by default
+to accept @code{Staff} and @code{FiguredBass} contexts within
+it, but not (for example) a @code{Lyrics} context. So in the
+following structure the lyrics are placed below the piano staff
+rather than between the two staves:
+
+@lilypond[verbatim,quote,relative=1]
+\new PianoStaff
+<<
+ \new Staff { e4 d c2 }
+ \addlyrics { Three blind mice }
+ \new Staff {
+ \clef "bass"
+ { c,1 }
+ }
+>>
+@end lilypond
+
+The @qq{accepts} list of a context can be modified to include
+additional nested contexts, so if we wanted the lyrics to appear
+between the two staves we could use:
+
+@lilypond[verbatim,quote,relative=1]
+\new PianoStaff \with { \accepts Lyrics }
+<<
+ \new Staff { e4 d c2 }
+ \addlyrics { Three blind mice }
+ \new Staff {
+ \clef "bass"
+ { c,1 }
+ }
+>>
+@end lilypond
+
+The opposite of @code{\accepts} is @code{\denies}; this removes a
+context from the @qq{accepts} list.
@node Explaining the Internals Reference
@section Explaining the Internals Reference
@menu
-* Navigating the program reference::
-* Layout interfaces::
-* Determining the grob property::
-* Naming conventions::
+* Navigating the program reference::
+* Layout interfaces::
+* Determining the grob property::
+* Naming conventions::
@end menu
@node Navigating the program reference
@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}.
+on @code{FingeringEvent} and one on @code{Fingering}.
-The page on @code{FingerEvent} describes the properties of the music
+The page on @code{FingeringEvent} describes the properties of the music
expression for the input @code{-2}. The page contains many links
forward. For example, it says
This engraver creates the following layout objects: @rinternals{Fingering}.
@end quotation
-In other words, once the @code{FingerEvent}s are interpreted, the
+In other words, once the @code{FingeringEvent}s are interpreted, the
@code{Fingering_engraver} plug-in will process them.
@end ignore
@item @rinternals{fingering-event}:
Music event type @code{fingering-event} is in Music expressions named
-@rinternals{FingerEvent}
+@rinternals{FingeringEvent}
@end itemize
This path goes against the flow of information in the program: it
@subsection Naming conventions
Another thing that is needed, is an overview of the various naming
-conventions:
+conventions:
scheme functions: lowercase-with-hyphens (incl. one-word
names)
@node Modifying properties
@section Modifying properties
+@c TODO change the menu and subsection node names to use
+@c backslash once the new macro to handle the refs
+@c is available. Need to find and change all refs at
+@c the same time. -td
+
@menu
-* Overview of modifying properties::
-* The \set command::
-* The \override command::
-* \set versus \override::
-* Objects connected to the input::
+* Overview of modifying properties::
+* The set command::
+* The override command::
+* The tweak command::
+* set versus override::
@end menu
-@node The \set command
+@node The set command
@subsection The @code{\set} command
@cindex properties
-@node The \override command
+@node The override command
@subsection The @code{\override} command
Commands which change output generally look like
and the program reference.
-@node \set versus \override
+@node The tweak command
+@subsection The @code{\tweak} command
+
+@funindex \tweak
+@cindex tweaking
+
+In some cases, it is possible to take a short-cut for tuning
+graphical objects. For objects that are created directly from
+an item in the input file, you can use the @code{\tweak} command.
+For example:
+
+@lilypond[relative=2,verbatim]
+< c
+ \tweak #'color #red
+ d
+ g
+ \tweak #'duration-log #1
+ a
+> 4
+-\tweak #'padding #8
+-^
+@end lilypond
+
+@cindex chord, modifying one note in
+
+But the main use of the @code{\tweak} command is to modify just
+one of a number of notation elements which start at the same musical
+moment, like the notes of a chord, or tuplet brackets which start
+at the same time.
+
+For an introduction to the syntax and uses of the tweak command
+see @rlearning{Tweaking methods}.
+
+The @code{\tweak} command sets a property in the following object
+directly, without requiring the grob name or context to be
+specified. For this to work, it is necessary for the @code{\tweak}
+command to remain immediately adjacent to the object to which it is
+to apply after the input file has been converted to a music stream.
+This is often not the case, as many additional elements are inserted
+into the music stream implicitly. For example, when a note which is
+not part of a chord is processed, Lilypond implicitly inserts a
+@code{ChordEvent} event before the note, so separating the tweak
+from the note. However, if chord symbols are placed round the
+tweak and the note, the @code{\tweak} command comes after the
+@code{ChordEvent} in the music stream, so remaining adjacent to the
+note, and able to modify it.
+
+So, this works:
+
+@lilypond[relative=2,verbatim,quote]
+<\tweak #'color #red c>4
+@end lilypond
+
+@noindent
+but this does not:
+
+@lilypond[relative=2,verbatim,quote]
+\tweak #'color #red c4
+@end lilypond
+
+When several similar items are placed at the same musical moment,
+the @code{\override} command cannot be used to modify just one of
+them -- this is where the @code{\tweak} command must be used.
+Items which may appear more than once at the same musical moment
+include the following:
+
+@c TODO expand to include any further uses of \tweak
+@itemize
+@item note heads of notes inside a chord
+@item articulation signs on a single note
+@item ties between notes in a chord
+@item tuplet brackets starting at the same time
+@end itemize
+
+@c TODO add examples of these
+
+@noindent
+and @code{\tweak} may be used to modify any single occurrence of
+these items.
+
+Notably the @code{\tweak} command cannot be used to modify stems,
+beams or accidentals, since these are generated later by note heads,
+rather than by music elements in the input stream. Nor can a
+@code{\tweak} command be used to modify clefs or time signatures,
+since these become separated from any preceding @code{\tweak}
+command in the input stream by the automatic insertion of extra
+elements required to specify the context.
+
+But the @code{\tweak} command can be used as an alternative to
+the @code{\override} command to modify those notational elements
+that do not cause any additional implicit elements to be added
+before them in the music stream. For example, slurs may be
+modified in this way:
+
+@lilypond[verbatim,quote,relative=1]
+c-\tweak #'thickness #5 ( d e f)
+@end lilypond
+
+Also several @code{\tweak} commands may be placed before a
+notational element -- all affect it:
+
+@lilypond[verbatim,quote,relative=1]
+c
+-\tweak #'style #'dashed-line
+-\tweak #'dash-fraction #0.2
+-\tweak #'thickness #3
+-\tweak #'color #red
+ \glissando
+f'
+@end lilypond
+
+The music stream which is generated from a section of an input file,
+including any automatically inserted elements, may be examined,
+see @ref{Displaying music expressions}. This may be helpful in
+determining what may be modified by a @code{\tweak} command.
+
+@seealso
+
+Learning Manual:
+@rlearning{Tweaking methods}.
+
+Notation Reference:
+@ref{Displaying music expressions}.
+
+@knownissues
+
+@cindex tweaks in a variable
+The @code{\tweak} command cannot be used inside a variable.
+
+@cindex tweaks in lyrics
+The @code{\tweak} commands cannot be used in @code{\lyricmode}.
+
+@cindex tweaking control points
+@cindex control points, tweaking
+
+The @code{\tweak} command cannot be used to modify the control
+points of just one of several ties in a chord, other than the first
+one encountered in the input file.
+
+@node set versus override
@subsection @code{\set} vs. @code{\override}
We have seen two methods of changing properties: @code{\set} and
property (modified with @code{\set}) was created.
-@node Objects connected to the input
-@subsection Objects connected to the input
-
-TODO: can't use \tweak in a variable
-
-@funindex \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
-
-@lilypond[relative=2,fragment,verbatim,ragged-right]
-<
- c
- \tweak #'color #red d
- g
- \tweak #'duration-log #1 a
->4-\tweak #'padding #10 -.
-@end lilypond
-
-As you can see, properties are set in the objects directly,
-without mentioning the grob name or context where this should be
-applied.
-
-This technique only works for objects that are directly connected to
-an @rinternals{Event} from the input, for example
-
-@itemize
-@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) or clefs (these are not caused by
-music inputs, but rather by the change of a property value).
-
-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
-does not change color. See @ref{Displaying music expressions}, for
-details.
-
-
@node Useful concepts and properties
@section Useful concepts and properties
* Input modes::
* Direction and placement::
* Distances and measurements::
+* Staff symbol properties::
* Spanners::
+* Visibility of objects::
+* Line styles::
+* Rotating objects::
@end menu
@node Input modes
@c TODO Add table showing these
-@strong{Context layout}
-
-Contexts are positioned in a system from top to bottom in the
-order in which they are encountered. Note, however, that a
-context will be created implicitly if a command is encountered
-when there is no suitable context available to contain it.
+@strong{Context layout order}
-@c TODO Add example ?
+Contexts are normally positioned in a system from top to bottom
+in the order in which they are encountered. Note, however, that
+a context will be created implicitly if a command is encountered
+when there is no suitable context available to contain it. When
+contexts are nested, the outer context will exclude inner contexts
+which are not included in its @qq{accepts} list; excluded contexts
+will be repositioned below the outer context.
-The default order in which contexts are laid out can be changed,
-see @ref{Aligning contexts}
+The default order in which contexts are laid out and the
+@qq{accepts} list can be changed, see @ref{Aligning contexts}.
@strong{Articulation direction indicators}
@node Distances and measurements
@subsection Distances and measurements
-DISCUSS after working on other sections.
+@cindex distances, absolute
+@cindex distances, scaled
+
+@funindex \mm
+@funindex \cm
+@funindex \in
+@funindex \pt
+
+Distances in LilyPond are of two types: absolute and scaled.
+
+Absolute distances are used for specifying margins, indents, and
+other page layout details, and are by default specified in
+millimeters. Distances may be specified in other units by
+following the quantity by @code{\mm}, @code{\cm},
+@code{\in}@tie{}(inches), or @code{\pt}@tie{}(points, 1/72.27
+of an inch). Page layout distances can also be specified in
+scalable units (see the following paragraph) by appending
+@code{\staff-space} to the quantity.
+Page layout is described in detail in @ref{Page formatting}.
+
+Scaled distances are always specified in units of the staff-space
+or, rarely, the half staff-space. The staff-space is the distance
+between two adjacent staff lines. The default value can be changed
+globally by setting the global staff size, or it can be overridden
+locally by changing the @code{staff-space} property of
+@code{StaffSymbol}. Scaled distances automatically scale with any
+change to the either the global staff size or the
+@code{staff-space} property of @code{StaffSymbol}, but fonts scale
+automatically only with changes to the global staff size.
+The global staff size thus enables the overall size of a rendered
+score to be easily varied. For the methods of setting the global
+staff size see @ref{Setting the staff size}.
+
+@funindex magstep
+
+If just a section of a score needs to be rendered to a different
+scale, for example an ossia section or a footnote, the global staff
+size cannot simply be changed as this would affect the entire score.
+In such cases the change in size is made by overriding both the
+@code{staff-space} property of @code{StaffSymbol} and the size of
+the fonts. A Scheme function, @code{magstep}, is available to
+convert from a font size change to the equivalent change in
+@code{staff-space}. For an explanation and an example of its use,
+see @rlearning{Length and thickness of objects}.
+
+@seealso
+
+Learning Manual:
+@rlearning{Length and thickness of objects}.
+
+Notation Reference:
+@ref{Page formatting},
+@ref{Setting the staff size}.
+
+
+@node Staff symbol properties
+@subsection Staff symbol properties
+
+@cindex adjusting staff symbol
+@cindex drawing staff symbol
+@cindex staff symbol, setting of
+
+@c TODO Extend or remove this section. See also NR 1.6.2 Staff symbol
+@c Need to think of uses for these properties. Eg 'line-positions
+@c is used in a snippet to thicken centre line.
+@c If retained, add @ref to here in 1.6.2 -td
+
+The vertical position of staff lines and the number of staff lines
+can be defined at the same time. As the following example shows,
+note positions are not influenced by the staff line positions.
+
+@warning{The @code{'line-positions} property overrides the
+@code{'line-count} property. The number of staff lines is
+implicitly defined by the number of elements in the list of values
+for @code{'line-positions}.}
+
+@lilypond[verbatim,quote,relative=1]
+\new Staff \with {
+ \override StaffSymbol #'line-positions = #'(7 3 0 -4 -6 -7)
+}
+{ a4 e' f b | d1 }
+@end lilypond
+
+The width of a staff can be modified. The units are staff
+spaces. The spacing of objects inside the staff is not affected by
+this setting.
-TODO: staff spaces. Maybe move into tweaks?
+@lilypond[verbatim,quote,relative=1]
+\new Staff \with {
+ \override StaffSymbol #'width = #23
+}
+{ a4 e' f b | d1 }
+@end lilypond
@node Spanners
@subsection Spanners
Many objects of musical notation extend over several notes or even
-several bars. Examples are crescendi, trills, tuplet brackets, and
-volta repeat brackets. Such objects are called @qq{spanners}, and
-have special properties to control their appearance and behaviour.
-Some of these properties are common to all spanners; others are
-restricted to a sub-set of the spanners.
+several bars. Examples are slurs, beams, tuplet brackets, volta
+repeat brackets, crescendi, trills, and glissandi. Such objects
+are collectively called @qq{spanners}, and have special properties to control
+their appearance and behaviour. Some of these properties are common
+to all spanners; others are restricted to a sub-set of the spanners.
+All spanners support the @code{spanner-interface}. A few, esentially
+those that draw a straight line between the two objects, support in
+addition the @code{line-spanner-interface}.
-@node Common properties
-@section Common properties
+@unnumberedsubsubsec Using the @code{spanner-interface}
-@menu
-* Controlling visibility of objects::
-* Line styles::
-* Rotating objects::
-* Aligning objects::
-@end menu
+This interface provides two properties that apply to several spanners.
-@node Controlling visibility of objects
-@subsection Controlling visibility of objects
+@strong{@i{The @code{minimum-length} property}}
-@c FIXME Write this section
+The minimum length of the spanner is specified by the
+@code{minimum-length} property. Increasing this usually has the
+necessary effect of increasing the spacing of the notes between the
+two end points. However, this override has no effect on
+many spanners, as their length is determined by other considerations.
+A few examples where it is effective are shown below.
-@node Line styles
-@subsection Line styles
+@ignore
+Works for:
+ Tie
+ MultiMeasureRest
+ Hairpin
+ Slur
+ PhrasingSlur
+
+Works as long as callback is made:
+ Glissando
+ Beam
+
+Works not at all for:
+ LyricSpace
+ LyricHyphen
+ LyricExtender
+ TextSpanner
+ System
-@c TODO: split the following explanations between expressive marks and
-@c text-related stuff. Perhaps create a new subsection named
-@c "Spanner limits", "Spanner boundaries"? -vv
+@end ignore
-Some performance indications, e.g., @i{rallentando} and
-@i{accelerando} and @i{trills} are written as text and are
-extended over many measures with lines, sometimes dotted or wavy.
+@lilypond[verbatim,quote,relative=2]
+a~a
+a
+% increase the length of the tie
+-\tweak #'minimum-length #5
+~a
+@end lilypond
-These all use the same routines as the glissando for drawing the
-texts and the lines, and tuning their behavior is therefore also
-done in the same way. It is done with a spanner, and the routine
-responsible for drawing the spanners is
-@code{ly:line-interface::print}. This routine determines the
-exact location of the two @i{span points} and draws a line in
-between, in the style requested.
+@lilypond[verbatim,quote,relative=2]
+a1
+\compressFullBarRests
+R1*23
+% increase the length of the rest bar
+\once \override MultiMeasureRest #'minimum-length = #20
+R1*23
+a1
+@end lilypond
-Here is an example of the different line styles available, and how
-to tune them.
+@lilypond[verbatim,quote,relative=2]
+a \< a a a \!
+% increase the length of the hairpin
+\override Hairpin #'minimum-length = #20
+a \< a a a \!
+@end lilypond
-@lilypond[relative=2,ragged-right,verbatim,fragment]
-d2 \glissando d'2
-\once \override Glissando #'style = #'dashed-line
-d,2 \glissando d'2
-\override Glissando #'style = #'dotted-line
-d,2 \glissando d'2
-\override Glissando #'style = #'zigzag
-d,2 \glissando d'2
-\override Glissando #'style = #'trill
-d,2 \glissando d'2
+This override can also be used to increase the length of slurs and
+phrasing slurs:
+
+@lilypond[verbatim,quote,relative=2]
+a( a)
+a
+-\tweak #'minimum-length #5
+( a)
+
+a\( a\)
+a
+-\tweak #'minimum-length #5
+\( a\)
@end lilypond
-The information that determines the end-points is computed
-on-the-fly for every graphic object, but it is possible to
-override these.
+For some layout objects, the @code{minimum-length} property becomes
+effective only if the @code{set-spacing-rods} procedure is called
+explicitly. To do this, the @code{springs-and-rods} property should
+be set to @code{ly:spanner::set-spacing-rods}. For example,
+the minimum length of a glissando has no effect unless the
+@code{springs-and-rods} property is set:
+
+@lilypond[verbatim,quote,relative=1]
+% default
+e \glissando c'
+
+% not effective alone
+\once \override Glissando #'minimum-length = #20
+e, \glissando c'
+
+% effective only when both overrides are present
+\once \override Glissando #'minimum-length = #20
+\once \override Glissando #'springs-and-rods = #ly:spanner::set-spacing-rods
+e, \glissando c'
+@end lilypond
-@lilypond[relative=2,ragged-right,verbatim,fragment]
-e2 \glissando f
+The same is true of the @code{Beam} object:
+
+@lilypond[verbatim,quote,relative=1]
+% not effective alone
+\once \override Beam #'minimum-length = #20
+e8 e e e
+
+% effective only when both overrides are present
+\once \override Beam #'minimum-length = #20
+\once \override Beam #'springs-and-rods = #ly:spanner::set-spacing-rods
+e8 e e e
+@end lilypond
+
+@strong{@i{The @code{to-barline} property}}
+
+The second useful property of the @code{spanner-interface} is
+@code{to-barline}. By default this is true, causing hairpins and
+other spanners which are terminated on the first note of a measure to
+end instead on the immediately preceding bar line. If set to false,
+the spanner will extend beyond the bar line and end on the note
+itself:
+
+@lilypond[verbatim,quote,relative=2]
+a \< a a a a \! a a a \break
+\override Hairpin #'to-barline = ##f
+a \< a a a a \! a a a
+@end lilypond
+
+This property is not effective for all spanners. For example,
+seting it to @code{#t} has no effect on slurs or phrasing slurs
+or on other spanners for which terminating on the bar line would
+not be meaningful.
+
+@unnumberedsubsubsec Using the @code{line-spanner-interface}
+
+Objects which support the @code{line-spanner-interface} include
+
+@itemize
+@item @code{DynamicTextSpanner}
+@item @code{Glissando}
+@item @code{TextSpanner}
+@item @code{TrillSpanner}
+@item @code{VoiceFollower}
+@end itemize
+
+The routine responsible for drawing the stencils for these spanners is
+@code{ly:line-interface::print}. This routine determines the
+exact location of the two end points and draws a line
+between them, in the style requested. The locations of the two
+end points of the spanner are computed on-the-fly, but it is
+possible to override their Y-coordinates. The
+properties which need to be specified are nested
+two levels down within the property hierarchy, but the syntax of
+the @code{\override} command is quite simple:
+
+@lilypond[relative=2,quote,verbatim]
+e2 \glissando b
+\once \override Glissando #'bound-details #'left #'Y = #3
\once \override Glissando #'bound-details #'right #'Y = #-2
-e2 \glissando f
+e2 \glissando b
@end lilypond
-The @code{Glissando} object, like any other using the
-@code{ly:line-interface::print} routine, carries a nested
-association list. In the above statement, the value for @code{Y}
-is set to @code{-2} for the association list corresponding to the
-right end point. Of course, it is also possible to adjust the
-left side with @code{left} instead of @code{right}.
+The units for the @code{Y} property are @code{staff-space}s,
+with the center line of the staff being the zero point.
+For the glissando, this is the value for @code{Y} at the
+X-coordinate corresponding to the center point of each note head,
+if the line is imagined to be extended to there.
If @code{Y} is not set, the value is computed from the vertical
-position of right attachment point of the spanner.
+position of the corresponding attachment point of the spanner.
-In case of a line break, the values for the span-points are
-extended with contents of the @code{left-broken} and
-@code{right-broken} sublists, for example
+In case of a line break, the values for the end points are
+specified by the @code{left-broken} and @code{right-broken}
+sub-lists of @code{bound-details}. For example:
@lilypond[relative=2,ragged-right,verbatim,fragment]
-\override Glissando #'breakable = ##T
+\override Glissando #'breakable = ##t
\override Glissando #'bound-details #'right-broken #'Y = #-3
c1 \glissando \break
f1
@end lilypond
-The following properties can be used for the
+
+A number of further properties of the @code{left} and
+@code{right} sub-lists of the @code{bound-details} property
+may be modified in the same way as @code{Y}:
@table @code
@item Y
-This sets the Y-coordinate of the end point, in staff space. By
-default, it is the center of the bound object, so for a glissando
-it points to the vertical center of the note head.
+This sets the Y-coordinate of the end point, in @code{staff-space}s
+offset from the staff center line. By default, it is the center of
+the bound object, so a glissando points to the vertical center of
+the note head.
-For horizontal spanners, such as text spanner and trill spanners,
+For horizontal spanners, such as text spanners and trill spanners,
it is hardcoded to 0.
@item attach-dir
-This determines where the line starts and ends in X-direction,
+This determines where the line starts and ends in the X-direction,
relative to the bound object. So, a value of @code{-1} (or
@code{LEFT}) makes the line start/end at the left side of the note
head it is attached to.
@item X
-This is the absolute coordinate of the end point. It is usually
-computed on the fly, and there is little use in overriding it.
+This is the absolute X-coordinate of the end point. It is usually
+computed on the fly, and overriding it has little useful effect.
@item stencil
Line spanners may have symbols at the beginning or end, which is
-contained in this sub-property. This is for internal use, it is
-recommended to use @code{text}.
+contained in this sub-property. This is for internal use; it is
+recommended that @code{text} be used instead.
@item text
-This is a markup that is evaluated to yield stencil. It is used
-to put @i{cresc.} and @i{tr} on horizontal spanners.
+This is a markup that is evaluated to yield the stencil. It is used
+to put @i{cresc.}, @i{tr} and other text on horizontal spanners.
@lilypond[quote,ragged-right,fragment,relative=2,verbatim]
\override TextSpanner #'bound-details #'left #'text
@item stencil-align-dir-y
@item stencil-offset
-Without setting this, the stencil is simply put there at the
-end-point, as defined by the @code{X} and @code{Y} sub properties.
-Setting either @code{stencil-align-dir-y} or @code{stencil-offset}
-will move the symbol at the edge relative to the end point of the
-line
+Without setting one of these, the stencil is simply put at the
+end-point, centered on the line, as defined by the @code{X} and
+@code{Y} sub-properties. Setting either @code{stencil-align-dir-y}
+or @code{stencil-offset} will move the symbol at the edge vertically
+relative to the end point of the line:
@lilypond[relative=1,fragment,verbatim]
\override TextSpanner #'bound-details
- #'left #'stencil-align-dir-y = #DOWN
+ #'left #'stencil-align-dir-y = #-2
\override TextSpanner #'bound-details
#'right #'stencil-align-dir-y = #UP
\override TextSpanner #'bound-details
- #'left #'text = #"gggg"
+ #'left #'text = #"ggg"
\override TextSpanner #'bound-details
- #'right #'text = #"hhhh"
+ #'right #'text = #"hhh"
c4^\startTextSpan c c c \stopTextSpan
@end lilypond
+Note that negative values move the text @emph{up}, contrary to the
+effect that might be expected, as a value of @code{-1} or
+@code{DOWN} means align the @emph{bottom} edge of the text with
+the spanner line. A value of @code{1} or @code{UP} aligns
+the top edge of the text with the spanner line.
+
@item arrow
-Setting this sub property to @code{#t} produce an arrowhead at the
+Setting this sub-property to @code{#t} produces an arrowhead at the
end of the line.
@item padding
-This sub property controls the space between the specified
-end-point of the line and the actual end. Without padding, a
+This sub-property controls the space between the specified
+end point of the line and the actual end. Without padding, a
glissando would start and end in the center of each note head.
@end table
-@c TODO: Move to 5.4.4
-
-The music function \endSpanners terminates spanners and hairpins
-after exactly one note.
+The music function @code{\endSpanners} terminates the spanner
+which starts on the immediately following note prematurely. It
+is terminated after exactly one note, or at the following bar line
+if @code{to-barline} is true and a bar line occurs before the next
+note.
@lilypond[verbatim,quote,ragged-right,relative=2,fragment]
\endSpanners
-c2 \startTextSpan c2
-c2 \< c2
+c2 \startTextSpan c2 c2
+\endSpanners
+c2 \< c2 c2
@end lilypond
-When using \endSpanners it is not necessary to close
+When using @code{\endSpanners} it is not necessary to close
\startTextSpan with \stopTextSpan, nor is it necessary to close
-hairpins with \!.
+hairpins with @code{\!}.
@rinternals{line-spanner-interface}.
+@node Visibility of objects
+@subsection Visibility of objects
+
+@cindex objects, visibility of
+@cindex grobs, visibility of
+@cindex visibility of objects
+
+There are four main ways in which the visibility of layout objects
+can be controlled: their stencil can be removed, they can be made
+transparent, they can be colored white, or their
+@code{break-visibility} property can be overridden. The first
+three apply to all layout objects; the last to just a few -- the
+@emph{breakable} objects. The Learning Manual introduces these
+four techniques, see @rlearning{Visibility and color of objects}.
+
+There are also a few other techniques which are specific to
+certain layout objects. These are covered under Special
+considerations.
+
+@menu
+* Removing the stencil::
+* Making objects transparent::
+* Painting objects white::
+* Using break-visibility::
+* Special considerations::
+@end menu
+
+
+@node Removing the stencil
+@unnumberedsubsubsec Removing the stencil
+
+@cindex stencil, removing
+
+Every layout object has a stencil property. By default this is set
+to the specific function which draws that object. If this property
+is overridden to @code{#f} no function will be called and the object
+will not be drawn. The default action can be recovered with
+@code{\revert}.
+
+@lilypond[quote,verbatim,relative=1]
+a1 a
+\override Score.BarLine #'stencil = ##f
+a a
+\revert Score.BarLine #'stencil
+a a a
+@end lilypond
+
+@node Making objects transparent
+@unnumberedsubsubsec Making objects transparent
+
+@cindex transparent, making objects
+
+Every layout object has a transparent property which by default is
+set to @code{#f}. If set to @code{#t} the object still occupies
+space but is made invisible.
+
+@lilypond[quote,verbatim,relative=2]
+a4 a
+\once \override NoteHead #'transparent = ##t
+a a
+@end lilypond
+
+@node Painting objects white
+@unnumberedsubsubsec Painting objects white
+
+@cindex objects, coloring
+@cindex coloring objects
+@cindex layers
+@cindex printing order
+@cindex overwriting objects
+@cindex objects, overwriting
+@cindex grobs, overwriting
+
+Every layout object has a color property which by default is set
+to @code{black}. If this is overridden to @code{white} the object
+will be indistinguishable from the white background. However,
+if the object crosses other objects the color of the crossing
+points will be determined by the order in which they are drawn,
+and this may leave a ghostly image of the white object, as shown
+here:
+
+@lilypond[quote,verbatim,relative=2]
+\override Staff.Clef #'color = #white
+a1
+@end lilypond
+
+This may be avoided by changing the order of printing the objects.
+All layout objects have a @code{layer} property which should be set
+to an integer. Objects with the lowest value of @code{layer} are
+drawn first, then objects with progressively higher values are drawn,
+so objects with higher values overwrite objects with lower values.
+By default most objects are assigned a @code{layer} value of
+@code{1}, although a few objects, including @code{StaffSymbol} and
+@code{BarLine}, are assigned a value of @code{0}. The order of
+printing objects with the same value of @code{layer} is indeterminate.
+
+In the example above the white clef, with a default @code{layer}
+value of @code{1}, is drawn after the staff lines (default
+@code{layer} value @code{0}), so overwriting them. To change this,
+the @code{Clef} object must be given in a lower value of
+@code{layer}, say @code{-1}, so that it is drawn earlier:
+
+@lilypond[quote,verbatim,relative=2]
+\override Staff.Clef #'color = #white
+\override Staff.Clef #'layer = #-1
+a1
+@end lilypond
+
+@node Using break-visibility
+@unnumberedsubsubsec Using break-visibility
+
+@c TODO Add making other objects breakable
+
+@cindex break-visibility
+
+Most layout objects are printed only once, but some like
+bar lines, clefs, time signatures and key signatures, may need
+to be printed twice when a line break occurs -- once at the end
+of the line and again at the start of the next line. Such
+objects are called @emph{breakable}, and have a property, the
+@code{break-visibility} property to control their visibility
+at the three positions in which they may appear -- at the
+start of a line, within a line if they are changed, and at the
+end of a line if a change takes place there.
+
+For example, the time signature
+by default will be printed at the start of the first line, but
+nowhere else unless it changes, when it will be printed at the
+point at which the change occurs. If this change occurs at the
+end of a line the new time signature will be printed at the start
+of the next line and a cautionary time signature will be printed
+at the end of the previous line as well.
+
+This behaviour is controlled by the @code{break-visibility}
+property, which is explained in
+@c Leave this ref on a newline - formats incorrectly otherwise -td
+@rlearning{Visibility and color of objects}. This property takes
+a vector of three booleans which, in order, determine whether the
+object is printed at the end of, within the body of, or at the
+beginning of a line. Or to be more precise, before a line break,
+where there is no line break, or after a line break.
+
+Alternatively, seven of the eight combinations may be specified
+by pre-defined functions, defined in @file{scm/output-lib.scm},
+where the last three columns indicate whether the layout objects
+will be visible in the positions shown at the head of the columns:
+
+@multitable @columnfractions .40 .15 .1 .1 .1
+@c TODO check these more carefully
+@headitem Function @tab Vector @tab Before @tab At no @tab After
+@headitem form @tab form @tab break @tab break @tab break
+
+@item @code{all-invisible} @tab @code{'#(#f #f #f)} @ @ @tab no @tab no @tab no
+@item @code{begin-of-line-visible} @tab @code{'#(#f #f #t)} @tab no @tab no @tab yes
+@item @code{end-of-line-visible} @tab @code{'#(#t #f #f)} @tab yes @tab no @tab no
+@item @code{all-visible} @tab @code{'#(#t #t #t)} @tab yes @tab yes @tab yes
+@c The center-visible function is not defined
+@c @item @code{center-visible} @tab @code{'#(#f #t #f)} @tab no @tab yes @tab no
+@item @code{begin-of-line-invisible} @tab @code{'#(#t #t #f)} @tab yes @tab yes @tab no
+@item @code{end-of-line-invisible} @tab @code{'#(#f #t #t)} @tab no @tab yes @tab yes
+@item @code{center-invisible} @tab @code{'#(#t #f #t)} @tab yes @tab no @tab yes
+@end multitable
+
+The @code{center-visible} function is not pre-defined.
+
+The default settings of @code{break-visibility} depend on the
+layout object. The following table shows all the layout objects
+of interest which are affected by @code{break-visibility} and the
+default setting of this property:
+
+@multitable @columnfractions .3 .3 .4
+
+@headitem Layout object @tab Usual context @tab Default setting
+
+@c omit Ambitus as it appears not to be affected by break-visibility -td
+@c @item @code{Ambitus} @tab as specified @tab @code{begin-of-line-visible}
+@item @code{BarLine} @tab @code{Score} @tab calculated
+@item @code{BarNumber} @tab @code{Score} @tab @code{begin-of-line-visible}
+@c omit the following item until it can be explained -td
+@c @item @code{BreakAlignGroup} @tab @code{Score} @tab calculated
+@item @code{BreathingSign} @tab @code{Voice} @tab @code{begin-of-line-invisible}
+@item @code{Clef} @tab @code{Staff} @tab @code{begin-of-line-visible}
+@item @code{Custos} @tab @code{Staff} @tab @code{end-of-line-visible}
+@item @code{DoublePercentRepeat} @tab @code{Voice} @tab @code{begin-of-line-invisible}
+@c omit KeyCancellation until it can be explained -td
+@c @item @code{KeyCancellation} @tab ?? @tab @code{begin-of-line-invisible}
+@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{RehearsalMark} @tab @code{Score} @tab @code{end-of-line-invisible}
+@item @code{TimeSignature} @tab @code{Staff} @tab @code{all-visible}
+
+@end multitable
+
+The example below shows the use of the vector form to control the
+visibility of barlines:
+
+@lilypond[quote,verbatim,relative=1,ragged-right]
+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)
+\break
+f4 g a b
+f4 g a b
+@end lilypond
+
+Although all three components of the vector used to override
+@code{break-visibility} must be present, not all of them are
+effective with every layout object, and some combinations may
+even give errors. The following limitations apply:
+
+@itemize @bullet
+@item Bar lines cannot be printed at start of line.
+@item A bar number cannot be printed at the start of the first
+line unless it is set to be different from 1.
+@item Clef -- see below
+@item Double percent repeats are either all printed or all
+suppressed. Use begin-of line-invisible to print and
+all-invisible to suppress.
+@item Key signature -- see below
+@item OctavateEight -- see below
+@end itemize
+
+@node Special considerations
+@unnumberedsubsubsec Special considerations
+
+@strong{@emph{Visibility following explicit changes}}
+
+@cindex key signature, visibility following explicit change
+@cindex explicitKeySignatureVisibility
+@cindex clef, visibility following explicit change
+@cindex explicitClefVisibility
+
+The @code{break-visibility} property controls the visibility of
+key signatures and changes of clef only at the start of lines,
+i.e. after a break. It has no effect on the visibility of the
+key signature or clef following an explicit key change or an
+explicit clef change within or at the end of a line. In the
+following example the key signature following the explicit change
+to B-flat major is still visible, even though @code{all-invisible}
+is set.
+
+@lilypond[quote,verbatim,relative=1,ragged-right]
+\key g \major
+f4 g a b
+% Try to remove all key signatures
+\override Staff.KeySignature #'break-visibility = #all-invisible
+\key bes \major
+f4 g a b
+\break
+f4 g a b
+f4 g a b
+@end lilypond
+
+The visibility of such explicit key signature and clef changes is
+controlled by the @code{explicitKeySignatureVisibility} and
+@code{explicitClefVisibility} properties. These are the equivalent
+of the @code{break-visibility} property and both take a vector of
+three booleans or the predefined functions listed above, exactly like
+@code{break-visibility}. Both are properties of the Staff context,
+not the layout objects themselves, and so they are set using the
+@code{\set} command. Both are set by default to @code{all-visible}.
+These properties control only the visibility of key signatures and
+clefs resulting from explicit changes and do not affect key
+signatures and clefs at the beginning of lines;
+@code{break-visibility} must still be overridden in the appropriate
+object to remove these.
+
+@lilypond[quote,verbatim,relative=1,ragged-right]
+\key g \major
+f4 g a b
+\set Staff.explicitKeySignatureVisibility = #all-invisible
+\override Staff.KeySignature #'break-visibility = #all-invisible
+\key bes \major
+f4 g a b \break
+f4 g a b
+f4 g a b
+@end lilypond
+
+@strong{@emph{Visibility of cautionary accidentals}}
+
+To remove the cautionary accidentals printed at an explicit key
+change, set the Staff context property @code{printKeyCancellation}
+to @code{#f}:
+
+@lilypond[quote,verbatim,relative=1,ragged-right]
+\key g \major
+f4 g a b
+\set Staff.explicitKeySignatureVisibility = #all-invisible
+\set Staff.printKeyCancellation = ##f
+\override Staff.KeySignature #'break-visibility = #all-invisible
+\key bes \major
+f4 g a b \break
+f4 g a b
+f4 g a b
+@end lilypond
+
+With these overrides only the accidentals before the notes remain
+to indicate the change of key.
+
+@c TODO Add visibility of cautionary accidentals before notes
+
+@strong{@emph{Automatic bars}}
+
+@cindex automaticBars
+@cindex bar lines, suppressing
+
+As a special case, the printing of bar lines can also be turned off
+by setting the @code{automaticBars} property in the Score context.
+If set to @code{#f}, bar lines will not be printed automatically;
+they must be explicitly created with a @code{\bar} command. Unlike
+the @code{\cadenzaOn} predefined command, measures are still counted.
+Bar generation will resume according to that count if this property
+is later set to @code{#t}. When set to @code{#f}, line breaks can
+occur only at explicit @code{\bar} commands.
+
+@c TODO Add example
+
+@strong{@emph{Octavated clefs}}
+
+@cindex octavated clefs, visibility of
+@cindex visibility of octavated clefs
+@cindex clefs, visibility of octavation
+
+The small octavation symbol on octavated clefs is produced by the
+@code{OctavateEight} layout object. Its visibility is controlled
+independently from that of the @code{Clef} object, so it is
+necessary to apply any required @code{break-visibility} overrides
+to both the @code{Clef} and the @code{OctavateEight} layout objects
+to fully suppress such clef symbols at the start of each line.
+
+For explicit clef changes, the @code{explicitClefVisibility}
+property controls both the clef symbol and any octavation symbol
+associated with it.
+
+
+@seealso
+Learning Manual:
+@rlearning{Visibility and color of objects}
+
+
+@node Line styles
+@subsection Line styles
+
+Some performance indications, e.g., @i{rallentando} and
+@i{accelerando} and @i{trills} are written as text and are
+extended over many measures with lines, sometimes dotted or wavy.
+
+These all use the same routines as the glissando for drawing the
+texts and the lines, and tuning their behavior is therefore also
+done in the same way. It is done with a spanner, and the routine
+responsible for drawing the spanners is
+@code{ly:line-interface::print}. This routine determines the
+exact location of the two @i{span points} and draws a line
+between them, in the style requested.
+
+Here is an example showing the different line styles available,
+and how to tune them.
+
+@lilypond[relative=2,ragged-right,verbatim,fragment]
+d2 \glissando d'2
+\once \override Glissando #'style = #'dashed-line
+d,2 \glissando d'2
+\override Glissando #'style = #'dotted-line
+d,2 \glissando d'2
+\override Glissando #'style = #'zigzag
+d,2 \glissando d'2
+\override Glissando #'style = #'trill
+d,2 \glissando d'2
+@end lilypond
+
+The locations of the end-points of the spanner are computed
+on-the-fly for every graphic object, but it is possible to
+override these:
+
+@c FIXME Complete
+@lilypond[relative=2,ragged-right,verbatim,fragment]
+e2 \glissando f
+\once \override Glissando #'bound-details #'right #'Y = #-2
+e2 \glissando f
+@end lilypond
+
+The value for @code{Y} is set to @code{-2} for the right end
+point. The left side may be similarly adjusted by specifying
+@code{left} instead of @code{right}.
+
+If @code{Y} is not set, the value is computed from the vertical
+position of the left and right attachment points of the spanner.
+
+Other adjustments of spanners are possible, for details, see
+@ref{Spanners}.
+
@node Rotating objects
@subsection Rotating objects
-@c FIXME Write this section
+Both layout objects and elements of markup text can be rotated by
+any angle about any point, but the method of doing so differs.
-@node Aligning objects
-@subsection Aligning objects
+@menu
+* Rotating layout objects::
+* Rotating markup::
+@end menu
+
+@node Rotating layout objects
+@unnumberedsubsubsec Rotating layout objects
+
+@cindex rotating objects
+@cindex objects, rotating
+
+All layout objects which support the @code{grob-interface} can be
+rotated by setting their @code{rotation} property. This takes a
+list of three items: the angle of rotation counter-clockwise,
+and the x and y coordinates of the point relative to the object's
+reference point about which the rotation is to be performed. The
+angle of rotation is specified in degrees and the coordinates in
+staff-spaces.
-@c FIXME Write this section
+The angle of rotation and the coordinates of the rotation point must
+be determined by trial and error.
+@cindex hairpins, angled
+@cindex angled hairpins
+
+There are only a few situations where the rotation of layout
+objects is useful; the following example shows one situation where
+they may be:
+
+@lilypond[quote,verbatim,relative=1]
+g4\< e' d' f\!
+\override Hairpin #'rotation = #'(20 -1 0)
+g,,4\< e' d' f\!
+@end lilypond
+
+@node Rotating markup
+@unnumberedsubsubsec Rotating markup
+
+All markup text can be rotated to lie at any angle by prefixing it
+with the @code{\rotate} command. The command takes two arguments:
+the angle of rotation in degrees counter-clockwise and the text to
+be rotated. The extents of the text are not rotated: they take
+their values from the extremes of the x and y coordinates of the
+rotated text. In the following example the
+@code{outside-staff-priority} property for text is set to @code{#f}
+to disable the automatic collision avoidance, which would push some
+of the text too high.
+
+@lilypond[quote,verbatim,relative=1]
+\override TextScript #'outside-staff-priority = ##f
+g4^\markup { \rotate #30 "a G" }
+b^\markup { \rotate #30 "a B" }
+des^\markup { \rotate #30 "a D-Flat" }
+fis^\markup { \rotate #30 "an F-Sharp" }
+@end lilypond
@node Advanced tweaks
@section Advanced tweaks
+This section discusses various approaches to fine tuning the
+appearance of the printed score.
+
@menu
+* Aligning objects::
* Vertical grouping of grobs::
-* Modifying ends of spanners::
* Modifying stencils::
+* Modifying shapes::
@end menu
+@seealso
+
+Learning Manual:
+@rlearning{Tweaking output},
+@rlearning{Other sources of information}.
+
+Notation Reference:
+@ref{Explaining the Internals Reference},
+@ref{Modifying properties},
+@ref{Interfaces for programmers}.
+
+Installed Files:
+@file{scm/@/define@/-grobs@/.scm}.
+
+Snippets:
+@rlsr{Tweaks and overrides}.
+
+Internals Reference:
+@rinternals{All layout objects}.
+
+@node Aligning objects
+@subsection Aligning objects
+
+Graphical objects which support the @code{self-alignment-interface} and/or
+the @code{side-position-interface} can be
+aligned to a previously placed object in a variety of ways. For a list of these objects, see
+@rinternals{self-alignment-interface} and @rinternals{side-position-interface}.
+
+All graphical objects have a reference point, a horizontal extent and a
+vertical extent. The horizontal extent is a pair of numbers
+giving the displacements from the reference point of the left and
+right edges, displacements to the left being negative. The
+vertical extent is a pair of numbers giving the displacement from
+the reference point to the bottom and top edges, displacements down
+being negative.
+
+An object's position on a staff is given by the values of the
+@code{X-offset} and @code{Y-offset} properties. The value of
+@code{X-offset} gives the displacement from the x coordinate of
+the reference point of the parent object, and the value of
+@code{Y-offset} gives the displacement from the center line of the
+staff. The values of @code{X-offset} and
+@code{Y-offset} may be set directly or may be set to be calculated
+by procedures in order to achieve alignment with the parent object
+in several ways.
+
+@warning{Many objects have special positioning considerations which
+cause any setting of @code{X-offset} or @code{Y-offset} to be
+ignored or modified, even though the object supports the
+@code{self-alignment-interface}.}
+
+For example, an accidental can be repositioned
+vertically by setting @code{Y-offset} but any changes to
+@code{X-offset} have no effect.
+
+Rehearsal marks may be aligned with
+breakable objects such as bar lines, clef symbols, time signature
+symbols and key signatures. There are special properties to be
+found in the @code{break-aligned-interface} for positioning rehearsal
+marks on such objects.
+
+@menu
+* Setting @code{X-offset} and @code{Y-offset} directly::
+* Using the @code{side-position-interface}::
+* Using the @code{self-alignment-interface}::
+* Using the @code{break-aligned-interface}::
+@end menu
+
+@node Setting @code{X-offset} and @code{Y-offset} directly
+@unnumberedsubsubsec Setting @code{X-offset} and @code{Y-offset} directly
+
+Numerical values may be given to the @code{X-offset} and @code{Y-offset}
+properties of many objects. The following example shows three
+notes with the default fingering position and the positions with @code{X-offset}
+and @code{Y-offset} modified.
+
+@lilypond[verbatim,quote,relative=2]
+a-3
+a
+-\tweak #'X-offset #0
+-\tweak #'Y-offset #0
+-3
+a
+-\tweak #'X-offset #-1
+-\tweak #'Y-offset #1
+-3
+@end lilypond
+
+@c TODO write more
+
+@node Using the @code{side-position-interface}
+@unnumberedsubsubsec Using the @code{side-position-interface}
+
+An object which supports the @code{side-position-interface} can be
+placed next to its parent object so that
+the specified edges of the two objects touch. The object may be
+placed above, below, to the right or to the left of the parent.
+The parent cannot be specified; it is determined by the order of
+elements in the input stream. Most objects have the associated
+note head as their parent.
+
+The values of the @code{side-axis} and @code{direction} properties
+determine where the object is to be placed, as follows:
+
+@c TODO add an example of each to the table
+
+@multitable @columnfractions .3 .3 .3
+@headitem @code{side-axis} @tab @code{direction} @tab
+@headitem property @tab property @tab Placement
+
+@item @code{0} @tab @code{-1} @tab left
+@item @code{0} @tab @code{1} @tab right
+@item @code{1} @tab @code{-1} @tab below
+@item @code{1} @tab @code{1} @tab above
+
+@end multitable
+
+When @code{side-axis} is @code{0}, @code{X-offset} should be set to
+the procedure @code{ly:side-position-interface::x-aligned-side}.
+This procedure will return the correct value of @code{X-offset} to
+place the object to the left or right side of the parent according
+to value of @code{direction}.
+
+When @code{side-axis} is @code{1}, @code{Y-offset} should be set to
+the procedure @code{ly:side-position-interface::y-aligned-side}.
+This procedure will return the correct value of @code{Y-offset} to
+place the object to the top or bottom of the parent according
+to value of @code{direction}.
+
+@c TODO Add examples
+
+@node Using the @code{self-alignment-interface}
+@unnumberedsubsubsec Using the @code{self-alignment-interface}
+
+@emph{Self-aligning objects horizontally}
+
+The horizontal alignment of an object which supports the
+@code{self-alignment-interface} is controlled by the value of
+the @code{self-alignment-X} property, provided the object's
+@code{X-offset} property is set to
+@code{ly:self-alignment-interface::x-aligned-on-self}.
+@code{self-alignment-X} may be given any
+real value, in units of half the total X extent of the
+object. Negative values move the object to the right, positive
+to the left. A value of @code{0} centers the object on the
+reference point of its parent, a value of @code{-1} aligns the
+left edge of the object on the reference point of its parent,
+and a value of @code{1} aligns the right edge of the object on the
+reference point of its parent. The symbols @code{LEFT},
+@code{CENTER} and @code{RIGHT} may be used instead of the values
+@code{-1, 0, 1} respectively.
+
+Normally the @code{\override} command would be used to modify the
+value of @code{self-alignment-X}, but the @code{\tweak} command
+can be used to separately align several annotations on a single
+note:
+
+@lilypond[quote,verbatim,relative=1]
+a'
+-\tweak #'self-alignment-X #-1
+^"left-aligned"
+-\tweak #'self-alignment-X #0
+^"center-aligned"
+-\tweak #'self-alignment-X #RIGHT
+^"right-aligned"
+-\tweak #'self-alignment-X #-2.5
+^"aligned further to the right"
+@end lilypond
+
+@emph{Self-aligning objects vertically}
+
+Objects may be aligned vertically in an analogous way to aligning
+them horizontally if the @code{Y-offset} property is set to
+@code{ly:self-alignment-interface::y-aligned-on-self}. However,
+other mechanisms are often involved in vertical alignment: the
+value of @code{Y-offset} is just one variable taken into account.
+This may make adjusting the value of some objects tricky.
+The units are just half the vertical extent of the object, which
+is usually quite small, so quite large numbers may be required.
+A value of @code{-1} aligns the lower edge of the object with
+the reference point of the parent object, a value of @code{0}
+aligns the center of the object with the reference point of the
+parent, and a value of @code{1} aligns the top edge of the object
+with the reference point of the parent. The symbols @code{DOWN},
+@code{CENTER}, @code{UP} may be substituted for @code{-1, 0, 1}
+respectively.
+
+@emph{Self-aligning objects in both directions}
+
+By setting both @code{X-offset} and @code{Y-offset}, an object may
+be aligned in both directions simultaneously.
+
+The following example shows how to adjust a fingering mark so
+that it nestles close to the note head.
+
+@lilypond[quote,verbatim,relative=2]
+a
+-\tweak #'self-alignment-X #0.5 % move horizontally left
+-\tweak #'Y-offset #ly:self-alignment-interface::y-aligned-on-self
+-\tweak #'self-alignment-Y #-1 % move vertically up
+-3 % third finger
+@end lilypond
+
+@ignore
+@unnumberedsubsubsec Using the @code{aligned-on-parent} procedures
+
+@c Cannot document as they do not seem to operate consistently on all objects -td
+@c TODO investigate further
+
+The @code{aligned-on-parent} procedures are used in the same way
+as the @code{aligned-on-self} procedures, they difference being
+that they permit an object to be aligned with the @emph{edges} of
+the parent rather than the parent's reference point. The following
+example shows the difference:
+
+@c TODO Add example
+
+@lilypond[verbatim,quote]
+@end lilypond
+
+@end ignore
+
+@ignore
+@unnumberedsubsubsec Using the @code{centered-on-parent} procedures
+
+@c Cannot document as they do not seem to operate consistently on all objects -td
+@c TODO investigate further
+
+@end ignore
+
+@c TODO The align-interface, BassFigureAlignment and VerticalAlignment
+
+@node Using the @code{break-aligned-interface}
+@unnumberedsubsubsec Using the @code{break-aligned-interface}
+
+Rehearsal marks may be aligned with notation objects other
+than bar lines. These objects include @code{ambitus},
+@code{breathing-sign}, @code{clef}, @code{custos}, @code{staff-bar},
+@code{left-edge}, @code{key-cancellation}, @code{key-signature}, and
+@code{time-signature}.
+
+By default, rehearsal marks will be horizontally centered above the
+object:
+
+@lilypond[verbatim,quote,relative=1]
+e1
+% the RehearsalMark will be centered above the Clef
+\override Score.RehearsalMark #'break-align-symbols = #'(clef)
+\key a \major
+\clef treble
+\mark "↓"
+e
+% the RehearsalMark will be centered above the TimeSignature
+\override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
+\key a \major
+\clef treble
+\time 3/4
+\mark "↓"
+e2.
+@end lilypond
+
+The alignment of the rehearsal mark relative to the notation object
+can be changed, as shown in the following example. In a score with
+multiple staves, this setting should be done for all the staves.
+
+@lilypond[verbatim,quote,relative=1]
+% The RehearsalMark will be centered above the KeySignature
+\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 KeySignature
+\once \override Score.KeySignature #'break-align-anchor-alignment = #LEFT
+\mark "↓"
+\key a \major
+e
+% The RehearsalMark will be aligned with the right edge of the KeySignature
+\once \override Score.KeySignature #'break-align-anchor-alignment = #RIGHT
+\key a \major
+\mark "↓"
+e
+@end lilypond
+
+The rehearsal mark can also be offset to the right or left of the left edge
+by an arbitrary amount. The units are staff-spaces:
+
+@lilypond[verbatim,quote,relative=1]
+% The RehearsalMark will be aligned with the left edge of the KeySignature
+% and then shifted right by 3.5 staff-spaces
+\override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
+\once \override Score.KeySignature #'break-align-anchor = #3.5
+\key a \major
+\mark "↓"
+e
+% The RehearsalMark will be aligned with the left edge of the KeySignature
+% and then shifted left by 2 staff-spaces
+\once \override Score.KeySignature #'break-align-anchor = #-2
+\key a \major
+\mark "↓"
+e
+@end lilypond
VerticalAxisGroup.
-@node Modifying ends of spanners
-@subsection Modifying ends of spanners
-
-@c FIXME Write this section
-
@node Modifying stencils
@subsection Modifying stencils
-@c FIXME Write this section
+All layout objects have a @code{stencil} property which is part of
+the @code{grob-interface}. By default, this property is usually
+set to a function specific to the object that is tailor-made to
+render the symbol which represents it in the output. For example,
+the standard setting for the @code{stencil} property of the
+@code{MultiMeasureRest} object is @code{ly:multi-measure-rest::print}.
+
+The standard symbol for any object can be replaced by modifying the
+@code{stencil} property to reference a different, specially-written,
+procedure. This requires a high level of knowledge of the internal
+workings of LilyPond, but there is an easier way which can often
+produce adequate results.
+
+This is to set the @code{stencil} property to the procedure which
+prints text -- @code{ly:text-interface::print} -- and to add a
+@code{text} property to the object which is set to contain the
+markup text which produces the required symbol. Due to the
+flexibility of markup, much can be achieved -- see in particular
+@ref{Graphic notation inside markup}.
+
+The following example demonstrates this by changing the note head
+symbol to a cross within a circle.
+
+@lilypond[verbatim,quote]
+XinO = {
+ \once \override NoteHead #'stencil = #ly:text-interface::print
+ \once \override NoteHead #'text = \markup {
+ \combine
+ \halign #-0.7 \draw-circle #0.85 #0.2 ##f
+ \musicglyph #"noteheads.s2cross"
+ }
+}
+\relative c'' {
+ a a \XinO a a
+}
+@end lilypond
+
+Any of the glyphs in the feta Font can be supplied to the
+@code{\musicglyph} markup command -- see @ref{The Feta font}.
+
+@c TODO Add inserting eps files or ref to later
+@c TODO Add inserting Postscript or ref to later
-@node Discussion of specific tweaks
-@section Discussion of specific tweaks
+@seealso
+
+Notation Reference:
+@ref{Graphic notation inside markup},
+@ref{Formatting text},
+@ref{Text markup commands},
+@ref{The Feta font}.
+
+
+@node Modifying shapes
+@subsection Modifying shapes
@menu
-* old Contexts explained::
+* Modifying ties and slurs::
@end menu
+@node Modifying ties and slurs
+@unnumberedsubsubsec Modifying ties and slurs
+
+Ties, slurs and phrasing slurs are drawn as third-order Bézier
+curves. If the shape of the tie or slur which is calculated
+automatically is not optimum, the shape may be modified manually by
+explicitly specifying the four control points required to define
+a third-order Bézier curve.
+
+Third-order or cubic Bézier curves are defined by four control
+points. The first and fourth control points are precisely the
+starting and ending points of the curve. The intermediate two
+control points define the shape. Animations showing how the curve
+is drawn can be found on the web, but the following description
+may be helpful. The curve starts from the first control point
+heading directly towards the second, gradually bending over to
+head towards the third and continuing to bend over to head towards
+the fourth, arriving there travelling directly from the third
+control point. The curve is entirely contained in the
+quadrilateral defined by the four control points.
+
+Here is an example of a case where the tie is not optimum, and
+where @code{\tieDown} would not help.
+
+@lilypond[verbatim,quote,relative=1]
+<<
+ { e1 ~ e }
+\\
+ { r4 <g c,> <g c,> <g c,> }
+>>
+@end lilypond
-@node old Contexts explained
-@subsection old Contexts explained
+One way of improving this tie is to manually modify its control
+points, as follows.
-@c FIXME Delete this section? It is in LM
-@c Or leave heading and go on from LM?
+The coordinates of the Bézier control points are specified in units
+of staff-spaces. The X@tie{}coordinate is relative to the reference
+point of the note to which the tie or slur is attached, and the
+Y@tie{}coordinate is relative to the staff center line. The
+coordinates are entered as a list of four pairs of decimal numbers
+(reals). One approach is to estimate the coordinates of the two
+end points, and then guess the two intermediate points. The optimum
+values are then found by trial and error.
-When music is printed, a lot of notational elements must be added to the
-output. For example, compare the input and output of the following example:
+It is useful to remember that a symmetric curve requires symmetric
+control points, and that Bézier curves have the useful property that
+transformations of the curve such as translation, rotation and
+scaling can be achieved by applying the same transformation to the
+curve's control points.
-@lilypond[quote,verbatim,relative=2,fragment]
-cis4 cis2. g4
-@end lilypond
+For the example above the following override gives a satisfactory
+tie:
-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 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
-@emph{Contexts}. Some examples of contexts are @code{Voice},
-@code{Staff}, and @code{Score}. They are hierarchical, for
-example: a @code{Staff} can contain many @code{Voice}s, and a
-@code{Score} can contain many @code{Staff} contexts.
+@lilypond[verbatim,quote,relative=1]
+<<
+ \once \override Tie
+ #'control-points = #'((1 . -1) (3 . 0.6) (12.5 . 0.6) (14.5 . -1))
+ { e1 ~ e1 }
+\\
+ { r4 <g c,> <g c,> <g c,>4 }
+>>
+@end lilypond
-@quotation
-@sourceimage{context-example,5cm,,}
-@end quotation
+@knownissues
-Each context has the responsibility for enforcing some notation rules,
-creating some notation objects and maintaining the associated
-properties. For example, the @code{Voice} context may introduce an
-accidental and then the @code{Staff} context maintains the rule to
-show or suppress the accidental for the remainder of the measure. The
-synchronization of bar lines is handled at @code{Score} context.
-
-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 @code{Score}
-and @code{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
-to define new contexts.
-
-
-A complete description of all available contexts is in the program
-reference, see
-@ifhtml
-@rinternals{Contexts}.
-@end ifhtml
-@ifnothtml
-Translation @expansion{} Context.
-@end ifnothtml
+It is not possible to modify shapes of ties or slurs by changing
+the @code{control-points} property if there are more than one at
+the same musical moment, not even by using the @code{\tweak}
+command.
-@c [TODO: describe propagation]
projects / lilypond.git / blobdiff