Re: relative offset of systems [WAS: Center-align a score]

[David Nalesnik]

On Thu, Apr 27, 2017 at 4:07 PM, David Nalesnik
<address@hidden> wrote:
> Hi Harm,
>
> On Thu, Apr 27, 2017 at 3:57 PM, Thomas Morley <address@hidden> wrote:
>> Hi David,
>>
>> nice stuff!
>>
>> Some comments, though:
>>
>> 2017-04-27 19:27 GMT+02:00 David Nalesnik <address@hidden>:
>>> On Thu, Apr 27, 2017 at 12:22 PM, David Nalesnik
>>> <address@hidden> wrote:
>>>
>>>>
>>>> I'll just quote the relevant changes with some context.
>>>>
>>>> Within the function make-page-stencil:
>>>>
>>>> [...]
>>>>
>>
>> I see no advantage to add 'extra-y' to the arguments.
>> Why not do the calculation in 'add-system' ...
>
> Good point.  Actually, I already incorporated this suggestion in a
> patch I'm currently testing.  (Middle of make doc.)  I decided to use
> an "extra-offset" property which allows for displacements along both
> axes.
>
>>
>>>>  (add-to-page (lambda (stencil x y extra-y)
>>>
>>> Oh, "nota bene" the above line too!
>>>
>>>>                     (set! page-stencil
>>>>                           (ly:stencil-add page-stencil
>>>>                             (ly:stencil-translate stencil
>>>>                               (cons
>>>>                                (+
>>>>                                 system-xoffset x)
>>>>                                (-
>>>>                                 0 y extra-y (prop 'top-margin))) ; NB
>>>>
>>>>                               )))))
>>>>      (add-system
>>>>       (lambda (system)
>>>>         (let* ((stencil (paper-system-stencil system))
>>>>                (y (ly:prob-property system 'Y-offset 0))
>>>>                (extra-y (ly:prob-property system 'extra-Y-offset 0)) ; NB
>>>>                (is-title (paper-system-title?
>>>>                           system)))
>>>>           (add-to-page stencil
>>>>             (ly:prob-property system 'X-offset 0.0)
>>>>             y
>>>>             extra-y) ; NB
>>
>>
>> It will fail if system-separator-markup is used.
>>
>> Here my attempt (for comparison I added greyed stencils)
>>
>>      (add-system
>>       (lambda (system)
>>         (let* ((stencil (paper-system-stencil system))
>>                (y (ly:prob-property system 'Y-offset 0))
>>                (extra-y (ly:prob-property system 'extra-Y-offset 0)) ;; NB
>>                (is-title (paper-system-title?
>>                           system)))
>>
>> ;;;; For comparison: print the greyed system-stencil without extra-y
>>           (add-to-page (stencil-with-color stencil '(0.8 0.8 0.8))
>>             (ly:prob-property system 'X-offset 0.0)
>>             y)
>> ;;;; The moved system-stencil
>>           (add-to-page stencil
>>             (ly:prob-property system 'X-offset 0.0)
>>             (+ y extra-y)) ;; NB
>>
>>             (if (and (ly:stencil? system-separator-stencil)
>>                      last-system
>>                      (not (paper-system-title? system))
>>                      (not (paper-system-title? last-system)))
>>                 (begin
>> ;;;; For comparison: print the greyed system-separator-stencil without 
>> 'extra-y
>>                   (add-to-page
>>                    (stencil-with-color system-separator-stencil '(0.8 0.8 
>> 0.8))
>>                    0
>>
>>                    (average (- last-y
>>                                (car (paper-system-staff-extents 
>> last-system)))
>>                             (- y
>>                                (cdr (paper-system-staff-extents system)))))
>>
>> ;;;; The moved system-separator-stencil
>>                   (add-to-page
>>                    system-separator-stencil
>>                    0
>>
>>                    (+
>>                      (average (- last-y
>>                                  (car (paper-system-staff-extents 
>> last-system)))
>>                               (- y
>>                                  (cdr (paper-system-staff-extents system))))
>>                      (/ extra-y 2)))))  ;; NB
>>             (set! last-system system)
>> ;;;; set last-y, taking extra-y into account
>>             (set! last-y (+ y extra-y)))))  ;; NB
>>
>> As an example I used:
>>
>> \paper {
>>   system-separator-markup = \slashSeparator
>>   ragged-last-bottom = ##t
>> }
>> top = \repeat unfold 5 { c''4 d'' e'' f'' }
>>
>> bottom = {
>>   \clef bass
>>   \repeat unfold 5 { c,1 }
>>   \break
>> }
>>
>> \new PianoStaff <<
>>   \new Staff {
>>     \top
>>     \top
>>     \top
>>   }
>>   \new Staff {
>>     \bottom
>>     \overrideProperty
>>     Score.NonMusicalPaperColumn.line-break-system-details
>>     #'((extra-Y-offset . 2))
>>     \bottom
>>     \overrideProperty
>>     Score.NonMusicalPaperColumn.line-break-system-details
>>     #'((extra-Y-offset . 5))
>>     \bottom
>>   }
>>>>
>>
>> png attached
>>
>
> Thanks so much for pointing this out.  I didn't notice that the
> variable "y" was used elsewhere.  As soon as the patch testing has run
> its course, I'll add this in.
>

Fixed.  Added system-separators to the regtest.

https://sourceforge.net/p/testlilyissues/issues/5127/

-David