Re: [Spam] Re: [Spam] Re: Spanner right-hand text may disappear when padded

[Rutger Hofman]

Thanks for all the help! First I post some rationale, then my real 
question, which is targeted at the developers I guess.

The behaviour I am after is a thing I really do want: it is visually 
confusing if the 'a tempo' comes halfway the 'poco rit.)' when it is 
clearly meant to be after it.

I am afraid that solutions involving staff-padding are not general 
enough; if I try to move the \markup{a tempo} in my example to the 
beginning of its bar, there is no value for right.text padding or 
staff-padding that lets it be both visible and at the same vertical 
position. And even then I am unsure if it will work for all 14 
instrument parts (the tempo indications are needed in all), the skyline 
can be wildly different.

OK... Now for the real question.

I am really unenlightened why the right.text (or for that matter, both 
left.text and right.text if the padding is chosen sufficiently large) 
disappears for largish values of padding. After all, the padding is 
intended to stretch outside the texts, isn't that correct?

For a quick attempt to see if things crash or whatever if this test is 
disabled, I cloned git and built on my Ubuntu, verified quickly that the 
unmodified install works, then commented out that test (line 329 in 
lily/line-spanner.cc) and ran again. Lo and behold, everything looks OK 
in my first quick tests.

I am not familiar with Lilypond internals, so this raises my question: 
what is this test for? What problems does it guard against? Should it 
only hold for other spanners than text spanners? Or for right-broken 
text spanners? Etc. Or is it just a bug/feature silently living on from 
the past?

Rutger

P.S. Building lilypond on my (up-to-date-ish but certainly not 
killer-class) PC take some minutes, not those tens of hours that the 
list spoke about lately.

On 10/12/2016 09:56 PM, David Nalesnik wrote:
> On Wed, Oct 12, 2016 at 2:04 PM, Rutger Hofman <address@hidden> wrote:
> > On 10/12/2016 06:17 PM, David Nalesnik wrote:
> > > On Wed, Oct 12, 2016 at 8:48 AM, David Nalesnik
> > > <address@hidden> wrote:
> > > > Harm,
> > > >
> > > > On Wed, Oct 12, 2016 at 8:13 AM, Thomas Morley <address@hidden>
> > > > wrote:
> > > >
> > > > > in this thread
> > > > >
> > > > > http://lilypond.1069038.n5.nabble.com/Alternate-scheme-text-spanner-ignores-spacers-td195195.html
> > > > > you researched the cause for problems while attaching TextSpanner to
> > > > > spacers using custom-scheme-engravers.
> > > > >
> > > > > May it be possible the problem is present in the original .cc-coded as
> > > > > well?
> > > > >
> > > > > At least I don't see any problem with attached TextSpanners as soon as
> > > > > I change a spacer to a real note-event in Rutger's code:
> > > >
> > > > It appears to be related to the X-position of the right-bound text:
> > > > if it's too far to the left, it won't be printed.
> > > >
> > > > Change the right-padding override in your example to 10, and the text
> > > > will also disappear.
> > >
> > > ly:line-spanner::print considers the properties left-bound-info and
> > > right-bound-info.  It returns '() if the sum of left.padding and
> > > right.padding is greater than the distance between the left and right
> > > ends of the spanner (as determined from "X" and "Y" stored in
> > > bound-details).  I can't say I follow the thinking, but that's what
> > > causes nothing to be printed when right.padding is set too high.
> > >
> > > (The variable for padding is confusingly named "gaps" in the code, by the
> > > way.)
> > >
> > > David
> >
> > For starters: thanks to you all for thinking along, and searching for an
> > analysis (and hopefully fix).
> >
> > The 'solution' of suppressing the spanner under these conditions doesn't
> > sound immediately logical to me. And this suppression only struck my eye for
> > spanners that cross a line break; which doesn't imply that it cannot occur
> > otherwise of course.
>
> The point I'm making is that the spanner was only suppressed in your
> original example because the value you chose for right.padding was too
> large -- large enough to put the right text before the left endpoint,
> which roughly is why the program gave you nothing.  If you use
>
> \override TextSpanner.bound-details.right.padding = #2
>
> the text is moved out from under the TextScript.  You can then
> override TextScript.staff-padding and TextSpanner.staff-padding to
> force an alignment.  As far as I know, you will have to align them
> yourself this way because the TextSpanner and TextScript are not
> grouped.  The inner-texts enhancement does offer a grouping of sorts.
>
> David