version that you are working on. See TRANSLATION for details.
@end ignore
-@c \version "2.11.61"
+@c \version "2.12.0"
@node Interfaces for programmers
@chapter Interfaces for programmers
@rlearning{Scheme tutorial}.
@menu
-* Music functions::
-* Programmer interfaces::
-* Building complicated functions::
-* Markup programmer interface::
-* Contexts for programmers::
+* Music functions::
+* Programmer interfaces::
+* Building complicated functions::
+* Markup programmer interface::
+* Contexts for programmers::
* Scheme procedures as properties::
-* Using Scheme code instead of \tweak::
+* Using Scheme code instead of \tweak::
* Difficult tweaks::
@end menu
This section discusses how to create music functions within LilyPond.
@menu
-* Overview of music functions::
-* Simple substitution functions::
-* Paired substitution functions::
-* Mathematics in functions::
-* Void functions::
-* Functions without arguments::
-* Overview of available music functions::
+* Overview of music functions::
+* Simple substitution functions::
+* Paired substitution functions::
+* Mathematics in functions::
+* Void functions::
+* Functions without arguments::
+* Overview of available music functions::
@end menu
@node Overview of music functions
Multiple variables may be used,
@lilypond[quote,verbatim,ragged-right]
-tempoMark = #(define-music-function (parser location padding marktext)
- (number? string?)
+tempoPadded = #(define-music-function (parser location padding tempotext)
+ (number? string?)
#{
- \once \override Score . RehearsalMark #'padding = $padding
- \once \override Score . RehearsalMark #'extra-spacing-width = #'(+inf.0 . -inf.0)
- \mark \markup { \bold $marktext }
+ \once \override Score.MetronomeMark #'padding = $padding
+ \tempo \markup { \bold $tempotext }
#})
\relative c'' {
-c2 e
-\tempoMark #3.0 #"Allegro"
-g c
+ \tempo \markup { "Low tempo" }
+ c4 d e f g1
+ \tempoPadded #4.0 #"High tempo"
+ g4 f e d c1
}
@end lilypond
and Scheme.
@menu
-* Input variables and Scheme::
-* Internal music representation::
+* Input variables and Scheme::
+* Internal music representation::
@end menu
@subsection Displaying music expressions
@cindex internal storage
+@cindex displaying music expressions
+@cindex internal representation, displaying
+@cindex displayMusic
@funindex \displayMusic
When writing a music function it is often instructive to inspect how
Stencil object given a number of arguments.
@menu
-* Markup construction in Scheme::
-* How markups work internally::
-* New markup command definition::
-* New markup list command definition::
+* Markup construction in Scheme::
+* How markups work internally::
+* New markup command definition::
+* New markup list command definition::
@end menu
@example
#(define-markup-list-command (paragraph layout props args) (markup-list?)
(let ((indent (chain-assoc-get 'par-indent props 2)))
- (interpret-markup-list layout props
+ (interpret-markup-list layout props
(make-justified-lines-markup-list (cons (make-hspace-markup indent)
args)))))
@end example
@section Contexts for programmers
@menu
-* Context evaluation::
-* Running a function on all layout objects::
+* Context evaluation::
+* Running a function on all layout objects::
@end menu
@node Context evaluation
Here is a function to use for @code{\applyOutput}; it blanks
note-heads on the center-line:
-@example
-(define (blanker grob grob-origin context)
- (if (and (memq (ly:grob-property grob 'interfaces)
- note-head-interface)
- (eq? (ly:grob-property grob 'staff-position) 0))
- (set! (ly:grob-property grob 'transparent) #t)))
-@end example
+@lilypond[quote,verbatim,ragged-right]
+#(define (blanker grob grob-origin context)
+ (if (and (memq 'note-head-interface (ly:grob-interfaces grob))
+ (eq? (ly:grob-property grob 'staff-position) 0))
+ (set! (ly:grob-property grob 'transparent) #t)))
+
+\relative {
+ e4 g8 \applyOutput #'Voice #blanker b d2
+}
+@end lilypond
@node Scheme procedures as properties
property is requested during the formatting process.
Most of the typesetting engine is driven by such callbacks.
-Properties that typically use callbacks include
+Properties that typically use callbacks include
@table @code
@item stencil
@end example
Note, however, that @code{\override}, applied to
-@code{NoteMusicalPaperColumn} and @code{PaperColumn}, still works as
+@code{NonMusicalPaperColumn} and @code{PaperColumn}, still works as
expected within @code{\context} blocks.
@end itemize