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%% DO NOT EDIT this file manually; it is automatically
%% generated from LSR http://lsr.di.unimi.it
%% Make any changes in LSR itself, or in Documentation/snippets/new/ ,
%% and then run scripts/auxiliar/makelsr.py
%%
%% This file is in the public domain.
\version "2.18.0"
\header {
= "devel, scheme-language, tweaks-and-overrides"
= "
When working with grob callbacks, it can be helpful to understand a
grob's @qq{ancestry}. Most grobs have @qq{parents} which influence the
positioning of the grob. X- and Y-parents influence the horizontal and
vertical positions for the grob, respectively. Additionally, each
parent may have parents of its own.
Unfortunately, there are several aspects of a grob's ancestry that can
lead to confusion:
* The types of parents a grob has may depend on context. * For some
grobs, the X- and Y-parents are the same. * A particular @qq{ancestor}
may be related to a grob in multiple ways. * The concept of
@qq{generations} is misleading.
For example, the @code{System} grob can be both parent (on the Y-side)
and grandparent (twice on the X-side) to a @code{VerticalAlignment}
grob.
This macro prints (to the console) a textual representation of a grob's
ancestry.
When called this way
@{
\\once \\override NoteHead.before-line-breaking = #display-ancestry
c @}
The following output is generated:
------------------------------------
NoteHead X,Y: NoteColumn
X: PaperColumn
X,Y: System
Y: VerticalAxisGroup
X: NonMusicalPaperColumn
X,Y: System
Y: VerticalAlignment
X: NonMusicalPaperColumn
X,Y: System
Y: System
"
= "Displaying grob ancestry"
} % begin verbatim
#(define (grob-name grob)
(if (ly:grob? grob)
(assoc-ref (ly:grob-property grob 'meta) 'name)
#f))
#(define (get-ancestry grob)
(if (not (null? (ly:grob-parent grob X)))
(list (grob-name grob)
(get-ancestry (ly:grob-parent grob X))
(get-ancestry (ly:grob-parent grob Y)))
(grob-name grob)))
#(define (format-ancestry lst padding)
(string-append
(symbol->string (car lst))
"\n"
(let ((X-ancestry
(if (list? (cadr lst))
(format-ancestry (cadr lst) (+ padding 3))
(symbol->string (cadr lst))))
(Y-ancestry
(if (list? (caddr lst))
(format-ancestry (caddr lst) (+ padding 3))
(symbol->string (caddr lst)))))
(if (equal? X-ancestry Y-ancestry)
(string-append
(format #f "~&")
(make-string padding #\space)
"X,Y: "
(if (list? (cadr lst))
(format-ancestry (cadr lst) (+ padding 5))
(symbol->string (cadr lst))))
(string-append
(format #f "~&")
(make-string padding #\space)
"X: " X-ancestry
"\n"
(make-string padding #\space)
"Y: " Y-ancestry
(format #f "~&"))))
(format #f "~&")))
#(define (display-ancestry grob)
(format (current-error-port)
"~3&~a~2%~a~&"
(make-string 36 #\-)
(format-ancestry (get-ancestry grob) 0)))
\relative c' {
\once \override NoteHead.before-line-breaking = #display-ancestry
f4
\once \override Accidental.before-line-breaking = #display-ancestry
\once \override Arpeggio.before-line-breaking = #display-ancestry
<f as c>4\arpeggio
}
|
