version that you are working on. See TRANSLATION for details.
@end ignore
-@c \version "2.11.51"
+@c \version "2.11.55"
@node Changing defaults
@chapter Changing defaults
+@strong{N.B. This Chapter is under heavy development at present.}
The purpose of LilyPond's design is to provide the finest output
quality as a default. Nevertheless, it may happen that you need to
@uref{http://@/lilypond@/.org/@/doc/@/stable/@/Documentation/@/user/@/lilypond@/-internals/,on@/-line},
but is also included with the LilyPond documentation package.
+@c TODO The following is at variance to what actually follows. Fix -td
+
There are four areas where the default settings may be changed:
@itemize
@menu
-* Interpretation contexts::
-* Explaining the Internals Reference::
-* Modifying properties::
-* Useful concepts and properties::
-* Common properties::
-* Advanced tweaks::
-* Discussion of specific tweaks::
+* Interpretation contexts::
+* Explaining the Internals Reference::
+* Modifying properties::
+* Useful concepts and properties::
+* Common properties::
+* Advanced tweaks::
+* Discussion of specific tweaks::
@end menu
This section describes what contexts are, and how to modify them.
@menu
-* Contexts explained::
-* Creating contexts::
-* Modifying context plug-ins::
-* Changing context default settings::
-* Defining new contexts::
-* Aligning contexts::
+* Contexts explained::
+* Creating contexts::
+* Modifying context plug-ins::
+* Changing context default settings::
+* Defining new contexts::
+* Aligning contexts::
@end menu
@c TODO Add introduction which explains contexts in generality -td
-@unnumberedsubsec Score - the master of all contexts
+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
processed, or explicitly when a @code{\new Score} command is
executed.
-@subheading Top-level contexts: Staff containers
+@node Top-level contexts - staff containers
+@unnumberedsubsubsec Top-level contexts - staff containers
-@subsubheading StaffGroup
+@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.
-@unnumberedsubsubsec ChoirStaff
+@strong{@emph{ChoirStaff}}
Identical to StaffGroup except that the bar lines of the contained
staves are not connected vertically.
-@unnumberedsubsubsec GrandStaff
+@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.
-@unnumberedsubsubsec PianoStaff
+@strong{@emph{PianoStaff}}
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.
-@unnumberedsubsubsec DrumStaff
-
-Handles typesetting for percussion. Can contain DrumVoice
-
-@unnumberedsubsubsec InnerStaffGroup
+@strong{@emph{InnerStaffGroup}}
TODO -td
-@unnumberedsubsubsec InnerChoirStaff
+@strong{@emph{InnerChoirStaff}}
TODO -td
-@heading Staff-level contexts
+@node Intermediate-level contexts - staves
+@unnumberedsubsubsec Intermediate-level contexts - staves
-@unnumberedsubsubsec Staff
+@strong{@emph{Staff}}
Handles clefs, bar lines, keys, accidentals. It can contain
Voice contexts.
-@unnumberedsubsubsec RhythmicStaff
+@strong{@emph{RhythmicStaff}}
Like Staff but for printing rhythms. Pitches are ignored;
the notes are printed on one line.
-@unnumberedsubsubsec TabStaff
+@strong{@emph{TabStaff}}
Context for generating tablature. By default lays the music
expression out as a guitar tablature, printed on six lines.
-@unnumberedsubsubsec VaticanaStaff
+@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.
-@unnumberedsubsubsec MensuralStaff
+@strong{@emph{MensuralStaff}}
Same as Staff, except that it is designed for typesetting
a piece in mensural style.
-@unnumberedsubsec Voice-level (bottom) contexts
+@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.
-@unnumberedsubsubsec Voice
+@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.
-@unnumberedsubsubsec VaticanaVoice
+@strong{@emph{VaticanaVoice}}
Same as Voice, except that it is designed for typesetting a piece
in gregorian style.
-@unnumberedsubsubsec MensuralVoice
+@strong{@emph{MensuralVoice}}
Same as Voice, with modifications for typesetting a piece in
mensural style.
-@unnumberedsubsubsec Lyrics
+@strong{@emph{Lyrics}}
Corresponds to a voice with lyrics. Handles the printing of a
single line of lyrics.
-@unnumberedsubsubsec DrumVoice
+@strong{@emph{DrumVoice}}
The voice context used in a percussion staff.
-@unnumberedsubsubsec FiguredBass
+@strong{@emph{FiguredBass}}
The context in which BassFigure objects are created from
input entered in @code{\figuremode} mode.
-@unnumberedsubsubsec TabVoice
+@strong{@emph{TabVoice}}
The voice context used within a TabStaff context. Usually left to
be created implicitly.
-@unnumberedsubsubsec ChordNames
+@strong{@emph{ChordNames}}
Typesets chord names.
@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,
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 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)
@menu
* Overview of modifying properties::
-* The \set command::
-* The \override command::
-* \set versus \override::
-* Objects connected to the input::
+* The set command::
+* The override command::
+* set versus override::
+* The tweak command::
@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 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
+@node The tweak command
+@subsection The @code{\tweak} command
TODO: can't use \tweak in a variable
@menu
-* Input modes::
-* Direction and placement::
-* Distances and measurements::
-* Spanners::
+* Input modes::
+* Direction and placement::
+* Distances and measurements::
+* Spanners::
@end menu
@node Input modes
@section Common properties
@menu
-* Controlling visibility of objects::
-* Line styles::
-* Rotating objects::
-* Aligning objects::
+* Controlling visibility of objects::
+* Line styles::
+* Rotating objects::
+* Aligning objects::
@end menu
-@c TODO Add new subsection Shapes of objects
-@c which would include Slur shapes
-@c with a Known issue: can't modify shapes if there are
-@c more than one at the same musical moment
-
@node Controlling visibility of objects
@subsection Controlling visibility of objects
-@c FIXME Write this section
+@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
The information that determines the end-points is computed
on-the-fly for every graphic object, but it is possible to
-override these.
+override these.
@lilypond[relative=2,ragged-right,verbatim,fragment]
e2 \glissando f
left side with @code{left} instead of @code{right}.
If @code{Y} is not set, the value is computed from the vertical
-position of right attachment point of the spanner.
+position of right 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
@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
@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.
+computed on the fly, and there is little use in overriding it.
@item stencil
Line spanners may have symbols at the beginning or end, which is
@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.
+
+@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.
+
+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 Aligning objects
@subsection Aligning objects
@section Advanced tweaks
@menu
-* Vertical grouping of grobs::
-* Modifying ends of spanners::
-* Modifying stencils::
+* Vertical grouping of grobs::
+* Modifying ends of spanners::
+* Modifying stencils::
+* Modifying shapes::
@end menu
@subsection Modifying ends of spanners
@c FIXME Write this section
+@c See earlier material in Line styles
@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
+
+@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
+* 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
+
+One way of improving this tie is to manually modify its control
+points, as follows.
+
+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.
+
+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.
+
+For the example above the following override gives a satisfactory
+tie:
+
+@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
+
+@knownissues
+
+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.
+
@node Discussion of specific tweaks
@section Discussion of specific tweaks
@menu
-* old Contexts explained::
+* old Contexts explained::
@end menu
projects / lilypond.git / blobdiff