Re: [bug?] Line_interface::line

[Juergen Reuter]

On Tue, 21 Sep 2004, Han-Wen Nienhuys wrote:

> ...
> > Well, ...
> > 
> > (1) There is no \unset command for grob properties (at least not that I 
> >     know of).  Hence, I guess by "unset dash-fraction" you mean 
> >     "\override TextSpanner #'dash-fraction = #'()"?  At least, this trick 
> >     seems to do the job.
> 
> 
> \revert TextSpanner #'dash-fraction
> 

Ok, that may work too if I can be sure that nobody else has touched this 
property before.  But I am targeting at the episem code (which should now 
more or less work in current CVS).  That is, I want to unset it without 
knowing its previous value (see the episem stuff in engraver-init.ly and 
gregorian-init.ly).  Therefore, setting it to #'() seems safer (though 
still assuming that the user does not touch it afterwards).

> > (2) I think it is a design flaw that you have to unset the dash-fraction 
> >     property (which, by default, is set to some value) in order to make 
> >     the style property work.  If this intended, it should at least be 
> >     clearly documented in the manual that changing the style property of 
> >     TextSpanner by default has no effect.
> 
> I think I don't get the entire picture. Can you post a .ly snippet of
> what you _would_  like to have working?
> 

Well, that's basically the snippet that I already sent:



startTextSpanner = #(make-span-event 'TextSpanEvent START)
stopTextSpanner = #(make-span-event 'TextSpanEvent STOP)

\score {
  \context Voice \transpose c c' {
    f a c' bes a g f g f
    \startTextSpanner
    g a bes
    \stopTextSpanner
    a g f f
  }
  \paper {
    \context {
        \Voice
        \override TextSpanner #'style = #'line
        \override TextSpanner #'edge-height = #'(0 . 0)
        \override TextSpanner #'padding = #0.5
        \override TextSpanner #'enclose-bounds = #1
        \override TextSpanner #'edge-text = #'("abc" . "def")
     }
  }
}



In this example, property "style" is set to "line", but I still get a 
dashed line.  That is, the "style" property does not have any effect.  To 
get a solid line, I have to unset dash-fraction.

However, if I set "style" to "zigzag", I *do* get a zigzag line, 
regardless if I have or have not set dash-fraction.  (But in this case the 
zigzag line is aligned completely wrong, as I already reported a view days 
ago; but that is another bug...)

That is, setting dash-fraction to some value prevents you from typesetting 
solid lines, while dashed lines and zigzag lines still work.  This does 
not sound very logical, does it?

Greetings,
Jürgen