Re: empty-stencil and point-stencil

[Trevor Daniels]

Trevor Daniels wrote Friday, June 26, 2009 7:32 AM


> Carl D. Sorensen wrote Wednesday, June 17, 2009 9:21 AM
>
> > On 6/16/09 1:51 PM, "Mark Polesky" <address@hidden> wrote:
> > > Trevor, could you add a bit to your recent LM 4.3.1 patch about
> > > empty-stencil and point-stencil? They are suitable substitutes 
> > > for
> > > #'stencil = ##f.
> > >
> > > \override <grob> #'stencil = #empty-stencil
> > > \override <grob> #'stencil = #point-stencil
> > >
> > > See
> > > http://lists.gnu.org/archive/html/lilypond-devel/2009-06/msg00332.html
> > > for a very recent discussion. I actually don't fully understand
> > > the subtleties of discerning when one is more appropriate than
> > > the other, but it sounds like you might!
> >
> > I don't understand why empty-stencil has a non-zero extent; that 
> > means it
> > takes up space.

I should have added this to my earlier mail, and I also
forgot to cc the list (well, it is early):

empty-stencil is defined in define-markup-commands.scm as:

(define-public empty-stencil (ly:make-stencil '() '(1 . -1) '(1 
. -1)))

Normally a left extent of 1 would be truncated to 0 and
a right extent of -1 to 0, but this doesn't seem to
happen.  I don't understand why.  Its effect is not as
expected, at least not when used on NoteHead, which is
why I used point-stencil.

> > I believe that point-stencil should be used to replace ##f, 
> > because we want
> > to take up no space, and point-stencil has zero extent.
>
> Yes; I used point-stencil in the example when I changed LM 4.3.1.
>
> Trevor