Re: "natural width" of a measure

[Urs Liska]

Hi David,


Am 11.04.2017 um 22:42 schrieb David Nalesnik:
> On Tue, Apr 11, 2017 at 3:34 PM, David Nalesnik
> <address@hidden> wrote:
>> On Tue, Apr 11, 2017 at 1:52 PM, Urs Liska <address@hidden> wrote:
>>>
>>> Am 11.04.2017 um 20:46 schrieb Malte Meyn:
>>>> Am 11.04.2017 um 20:36 schrieb Urs Liska:
>>>>> So, is there any moment in the compilation process where the natural,
>>>>> unstretched length of a measure can be calculated? It doesn't have to be
>>>>> an easily-read property and can involve calculation, but actually the x
>>>>> position of the barlines would be an easy target - *if* there's this
>>>>> magic moment in the compilation pipeline ;-)
>>>> Maybe you could experiment with the ly:one-line-breaking?
>>> I don't think so (only, of course, to investigate how much can be done
>>> on the internal level).
>>> Basically what I'm after is a ly:cheap-line-breaking mode that doesn't
>>> care at all about overall appearance or good page turns but instead
>>> simply places as many measures in a line as fit naturally. If then a
>>> line break changes and I know the natural width of the measures I can
>>> determine before compilation how many measures will fit on the *next*
>>> system.
>>>
>> But spacing depends on the sorts of durations present -- the most
>> common duration, the shortest duration.

I think I have expressed myself poorly.
I mean that after a first full engraving I would know the natural width
of a measure (as if it were typeset ragged-right). When now something
(e.g. additional notes) forces the line breaking to be changed I can
take the - known - natural widths of the following measures and
calculate which measures would fit into the next system.

>>
>> Do you mean to typeset each measure as if it's in isolation, without
>> stretching based on surrounding measures?
>>
>> For example,
>>
>> \version "2.19.59"
>>
>> \layout { ragged-right = ##t }
>>
>> {
>>   \repeat unfold 16 { c''16 }
>>   \repeat unfold 4 { c''4 }
>>   c''1
>>   c''2 c''2
>>   \repeat unfold 64 { c''64 }
>> }
>>
>> \layout {
>>   \context {
>>     \Score
>>     \override SpacingSpanner.common-shortest-duration = #'()
>>   }
>> }

No, I just want to know how much space a measure would need if it were
ragged-right but still have the actual engraving stretched to justified
lines.

>>
>> %%
>>
>> Alternately, you could create a \newSpacingSection every measure,
>> though this gives different values.  Don't know why.
>>
>> %%%%%%%%%%%%%%%%%%%%%%%%
>>
>> Here's how you can determine the widths of measures.  Note that I've
>> put everything on one line, so that the \once \override of the
>> NoteHead gives access to every column in the score.  You can adjust
>> what alignment objects are used to gauge width by changing the symbol
>> in ly:paper-column::break-align-width (available as of 2.19.59).
>> Right now, it's BreakAlignment objects to give you an extent
>> considering all prefatory materials.  staff-bar would give extents of
>> the bar lines.
>>
>> \version "2.19.59"
>>
>> \paper {
>>   page-breaking = #ly:one-line-breaking
>> }
>>
>> #(define (display-measure-widths grob)
>>    (let* ((sys (ly:grob-system grob))
>>           (cols (ly:grob-array->list (ly:grob-object sys 'columns)))
>>           (nmpcs
>>            (filter
>>             (lambda (elt)
>>               (and (grob::has-interface elt 'paper-column-interface)
>>                    (eq? #t (ly:grob-property elt 'non-musical))))
>>             cols))
>>           (widths
>>            (map
>>             (lambda (c) (ly:paper-column::break-align-width c
>> '(break-alignment)))
>>             nmpcs))
>>           (widths (sort widths (lambda (x y) (< (car x) (car y)))))
>>           )
>>      (pretty-print widths)))
>> {
>>
>>   \once \override NoteHead.after-line-breaking = #display-measure-widths
>>   \repeat unfold 4 { c''8. c''16}
>>   \repeat unfold 4 { c''4 }
>>   c''1
>>   c''2 c''2
>>   \repeat unfold 64 { c''64 }
>> }
>>
>> \layout {
>>   \context {
>>     \Score
>>     \override SpacingSpanner.common-shortest-duration = #'()
>>   }
>> }
>>
>> Hope this helps with something!
>>

I'll have to look into this tomorrow. RIght now it's too late to install
another LilyPond ...

> Oh, I should have mentioned that the function is showing the extents
> of objects held by the columns organizing barlines, clefs, key
> signatures, etc --  not measure lengths.  Finding the measures will
> involve an extra fun step.

Looking forward to that ;-)

Best
Urs

>
> David

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