Re: Eliminates pure-print-callbacks list (issue 7300082)

[k-ohara5a5a]

It does looks reasonable to put the promise that a stencil does not
change with line-spacing, near the definiton fo the stencil, rather than
in a separate list.

Just one question.  If we override the stencil
 \override NoteHead #'stencil = #stencil-notehead
then formerly LilyPond would avoid drawing it until after note-spacing,
giving an empty extent to note-spacing, so we would provide an estimated
extent like
 \override NoteHead #'minimum-Y-extent = #'(-0.5 . 0.5)
for use in spacing of notes and accidentals.

Now it seems the default will be that a user's stencil *is* evaluated at
the note-spacing stage, if the stencil it replaces was safe to evaluate
at that time.  Is that what you wanted?


https://codereview.appspot.com/7300082/diff/4002/scm/define-grobs.scm
File scm/define-grobs.scm (left):

https://codereview.appspot.com/7300082/diff/4002/scm/define-grobs.scm#oldcode2728
scm/define-grobs.scm:2728: (define pure-print-callbacks
This could have had a comment: "These print routines do not depend on
the spacing of a line, and we require that they do not depend on the
spacing of a line, so they can be evaluated to determine the space
needed at the note-spacing stage."

https://codereview.appspot.com/7300082/diff/4002/scm/output-lib.scm
File scm/output-lib.scm (right):

https://codereview.appspot.com/7300082/diff/4002/scm/output-lib.scm#newcode60
scm/output-lib.scm:60:
;; Using this as a callback for a grob's Y-extent promises
;;  that the grob's stencil does not depend on line-spacing.
;; We use this promise to figure the space required by Clefs
;;  and such at the note-spacing stage.

https://codereview.appspot.com/7300082/