Re: Broken Forbid_line_break_engraver with Completion_heads

[Mats Bengtsson]

I agree with Trevor. This is a feature, not a bug. If you search the 
mailing list archives, you
will find a number of complaints and questions about the fact that you 
couldn't get a line break
when the Completion_heads_engraver had split notes, even though you 
normally can have a
line break if the same tie had been inserted manually. The only reason 
that the discussion about
Forbid_line_break_engraver in combination with 
Completion_heads_engraver, was introduced
in the manual, was to show how to workaround this previous silly 
limitation.

  /Mats

Trevor Daniels wrote:
> Carl
>
> Why do you want a tied note to forbid a line break?
> It is preferable that it permits it, surely?
>
> Trevor
>
> ----- Original Message ----- From: "Carl D. Sorensen" 
> <address@hidden>
> To: "LilyPond Development" <address@hidden>
> Cc: "Han-Wen Nienhuys" <address@hidden>
> Sent: Friday, August 15, 2008 3:07 AM
> Subject: Broken Forbid_line_break_engraver with Completion_heads
>
>
> The code below
>
> %%%%%
> \paper{
>  ragged-right=##f
>  line-width=3\cm
>  indent=0\cm
> }
>
> \new Voice \with {
> \remove "Note_heads_engraver"
> \consists "Completion_heads_engraver"
> %\remove "Forbid_line_break_engraver"
> }
> \relative c'  {
>  e4 e e e2 % Line break should be forbidden here, but it's not
>  f4 f f
> }
>
> %%%%%%%%%%%
>
> caused both measures to be compressed onto one line up until 2.11.45-1.
>
> In all later releases, each measure gets its own line, which I think the
> Forbid_line_break_engraver should prevent.
>
> The behavior changed at commit 0030e7e6ab44b0050238ba2e5e220b184cde70b,
> when completionBusy was added to the Melisma and the "length of the
> generated note head" was adjusted so the "busyGrobs list is correctly
> calculated".
>
> I think that this means there is now no busyGrob crossing the measure
> boundary, to Forbid_line_break_engraver is free to break.
>
> I suspect that the fix is to have Forbid_line_break_engraver check both
> busyGrobs and completionBusy, but I don't know the code well enough to 
> make
> this change.
>
> The commit that changed the behavior was made by Han-Wen.
>
> If you'd like, I'll file this as a bug report.
>
> Thanks,
>
> Carl
>
>
>
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--
=============================================
        Mats Bengtsson
        Signal Processing
        School of Electrical Engineering
        Royal Institute of Technology (KTH)
        SE-100 44  STOCKHOLM
        Sweden
        Phone: (+46) 8 790 8463                         
       Fax:   (+46) 8 790 7260
        Email: address@hidden
        WWW: http://www.s3.kth.se/~mabe
=============================================