Re: Size of the arpeggio's arrow

[Thomas Morley]

Am Do., 5. Dez. 2019 um 20:01 Uhr schrieb Thomas Morley
<address@hidden>:
>
> Am Do., 5. Dez. 2019 um 19:02 Uhr schrieb Thomas Morley
> <address@hidden>:
> >
> > Am Do., 5. Dez. 2019 um 18:17 Uhr schrieb Thomas Morley
> > <address@hidden>:
> > >
> > > Am Do., 5. Dez. 2019 um 17:57 Uhr schrieb Paolo Prete <address@hidden>:
> > > >
> > > >
> > > > Hi Thomas.
> > > > Yes, I'm interested. I could not find any snippet for that, nor a 
> > > > corresponding property for "Arpeggio" in the "Lilypond Internals 
> > > > Reference"
> > > > Thanks.
> > > >
> > > > Il giovedì 5 dicembre 2019, 16:22:12 GMT, Thomas Morley 
> > > > <address@hidden> ha scritto:
> > > >
> > > >
> > > > Am Do., 5. Dez. 2019 um 15:07 Uhr schrieb Paolo Pr <address@hidden>:
> > > >
> > > > >
> > > > > (I re-post this because it seems that mails from Yahoo services, like 
> > > > > some of my previous posts, are filtered as spam)
> > > > >
> > > > > Hello,
> > > > >
> > > > > how can I modify the size of the arrow of an \arpeggioArrowUp/Down 
> > > > > object?
> > > > >
> > > > > Thanks
> > > >
> > > > >
> > > >
> > > > There is no builtin method to do so.
> > > > You could create your own stencil, though.
> > > >
> > > > Interested in learning howto?
> > > >
> > > >
> > > > Cheers,
> > > >   Harm
> > > >
> > > >
> > >
> > > Ok :)
> > > So what do we want?
> > > While applying \arpeggioArrowUp we want the usual arpeggio, but the
> > > added arrow-head should be sized as we want.
> > >
> > > Alas, as soon as we set \arpeggioArrowUp the default is there.
> > > Mmhh, what exactly does \arpeggioArrowUp?
> > > Looking into property-init.ly (found by some search-functions of your
> > > editor or some grepping):
> > >
> > > arpeggioArrowUp = {
> > >   \revert Arpeggio.stencil
> > >   \revert Arpeggio.X-extent
> > >   \override Arpeggio.arpeggio-direction = #UP
> > > }
> > >
> > > Interesting is arpeggio-direction, looks like it triggers the arrowed 
> > > arpeggio.
> > > Let's proof:
> > >
> > > {
> > >   \arpeggioArrowUp
> > >   R1
> > >   \override Arpeggio.arpeggio-direction = #'()
> > >   <b d' f' b'>\arpeggio
> > > }
> > >
> > > And indeed the arrow-head is gone.
> > >
> > > Now we can recreate the _default_-stencil explicitely, using the
> > > default-stencil, found in IR.
> > > I.e. the procedure ly:arpeggio::print
> > > NB, although we've set \arpeggioArrowUp
> > >
> > > {
> > >   \arpeggioArrowUp
> > >   R1
> > >   \override Arpeggio.arpeggio-direction = #'()
> > >   \override Arpeggio.stencil =
> > >   #(lambda (grob)
> > >      (ly:arpeggio::print grob))
> > >   <b d' f' b'>\arpeggio
> > > }
> > >
> > > Let us put the arpeggio-direction into the stencil-override for 
> > > conveniance:
> > >
> > > {
> > >   \arpeggioArrowUp
> > >   R1
> > >   \override Arpeggio.stencil =
> > >   #(lambda (grob)
> > >      (ly:grob-set-property! grob 'arpeggio-direction '())
> > >      (ly:arpeggio::print grob))
> > >   <b d' f' b'>\arpeggio
> > > }
> > >
> > > Now we only need to add a suitable arrowhead to the stencil and are done.
> > >
> > >
> > > So I need a little break, I'm cooking right now ;)
> > >
> > >
> > > Cheers,
> > >   Harm
> >
> > Now let's care about the arrow-head.
> > Probably you noticed the arrow-heads in A.8 "The Emmentaler font" of NR:
> > "scripts.arpeggio.arrow.1" and "scripts.arpeggio.arrow.M1"
> >
> > Likely it's best to select the arrow-head depending on the direction, with
> >
> >   (format #f
> >     "scripts.arpeggio.arrow.~a1"
> >     (if (negative? arp-dir)
> >         "M"
> >         ""))
> >
> > where arp-dir is the arpeggio-direction, i.e. for no we disregard what
> > I said earlier.
> >
> > Now we have the glyph and we need to look it up in the font.
> > Ok, so we need to get the font.
> >
> > Maybe you stumbled across ly:grob-default-font already, with this one
> > we get the font.
> > Now we can lookup, using ly:font-get-glyph.
> >
> > ly:grob-default-font and ly:font-get-glyph can be found in IR.
> > To learn how to use them you will need to look throuw our source-code, 
> > though.
> > I don't know much examples for it.
> >
> > Disregarding the arpeggio, only putting out the arrow-head it makes for:
> >
> >
> > myArpeggio =
> >   \override Arpeggio.stencil =
> >   #(lambda (grob)
> >     (let* ((arp-dir (ly:grob-property grob 'arpeggio-direction))
> >            (arrow-glyph
> >              (format #f
> >                "scripts.arpeggio.arrow.~a1"
> >                (if (negative? arp-dir)
> >                    "M"
> >                    ""))))
> >
> >      (ly:font-get-glyph (ly:grob-default-font grob) arrow-glyph)))
> >
> > {
> >   \arpeggioArrowUp
> >   \myArpeggio
> >   <b d' f' b'>\arpeggio
> >
> >
> >   \arpeggioArrowDown
> >   \myArpeggio
> >   <b d' f' b'>\arpeggio
> > }
> >
> > Now we've created single arrow-heads depending on the direction.
> >
> >
> > TODO:
> > Adjust size of the arrow-heads
> > Move them to the place where they should be
> > Combine it with the usual trill-like arpeggio-line
> >
> >
> > Laters,
> >   Harm
>
> Next steps: move the arrow-heads correctly/combine with arpeggio-line
>
> For better debugging I colored the arrows red.
> To move them correctly we need the y-ext of the arpeggio-stencil.
> If arppeggio-direction is up we can use the cdr of the arpeggio-stencil.
> But if arppeggio-direction is down (car stil-y-ext) is not sufficient,
> we need to take the y-ext of the arrow into account as well.
> Move is done with ly:stencil-translate-axis.
> Finally simply add them with ly:stencil-add.
>
> myArpeggio =
>   \override Arpeggio.stencil =
>   #(lambda (grob)
>     (let* ((arp-dir (ly:grob-property grob 'arpeggio-direction))
>            (arrow-glyph
>              (format #f
>                "scripts.arpeggio.arrow.~a1"
>                (if (negative? arp-dir)
>                    "M"
>                    "")))
>            (font (ly:grob-default-font grob))
>            (arrow-head-stil (ly:font-get-glyph font arrow-glyph))
>            (red-arrow (stencil-with-color arrow-head-stil red))
>            (red-arrow-y-ext (ly:stencil-extent red-arrow Y)))
>
>       (ly:grob-set-property! grob 'arpeggio-direction '())
>
>       (let* ((stil (ly:arpeggio::print grob))
>              (stil-y-ext (ly:stencil-extent stil Y)))
>
>         (ly:stencil-add
>           (ly:stencil-translate-axis
>             red-arrow
>             (if (negative? arp-dir)
>                 (- (car stil-y-ext) (interval-length red-arrow-y-ext))
>                 (cdr stil-y-ext))
>             Y)
>           stil))))
>
> {
>   \arpeggioArrowUp
>   \myArpeggio
>   <b d' f' b'>\arpeggio
>
>
>   \arpeggioArrowDown
>   \myArpeggio
>   <b d' f' b'>\arpeggio
> }
>
> TODO Resize the arrow-head
>
>
> Cheers,
>   Harm

In my last mail I actually sort of recreated the arrowed arpeggio-stencil.
This is fine, because no we can start manipulating it.
Let's try to scale up the arrows a bit, using ly:stencil-scale, see IR.


myArpeggio =
  \override Arpeggio.stencil =
  #(lambda (grob)
    (let* ((arp-dir (ly:grob-property grob 'arpeggio-direction))
           (arrow-glyph
             (format #f
               "scripts.arpeggio.arrow.~a1"
               (if (negative? arp-dir)
                   "M"
                   "")))
           (font (ly:grob-default-font grob))
           (arrow-head-stil (ly:font-get-glyph font arrow-glyph))
           (red-arrow
             (ly:stencil-scale
               (stencil-with-color arrow-head-stil red)
               1.5 1.5))
           (red-arrow-y-ext (ly:stencil-extent red-arrow Y)))

      (ly:grob-set-property! grob 'arpeggio-direction '())

      (let* ((stil (ly:arpeggio::print grob))
             (stil-y-ext (ly:stencil-extent stil Y))
             (stil-x-ext (ly:stencil-extent stil X)))
        (ly:stencil-add
          (ly:stencil-translate-axis
            red-arrow
            (if (negative? arp-dir)
                (- (car stil-y-ext) (interval-length red-arrow-y-ext))
                (cdr stil-y-ext))
            Y)
          stil))))

{
  \arpeggioArrowUp
  \myArpeggio
  <b d' f' b'>\arpeggio


  \arpeggioArrowDown
  \myArpeggio
  <b d' f' b'>\arpeggio
}


Though, now the arrow-head is a little off regarding x-axis.

We need to compensate, best to move him back where he belongs by half
the difference of arpeggio and arrow-stils widths.
Thus we switch from ly:stencil-translate-axis to ly:stencil-translate
expecting a pair for x/y.

Makes for:

myArpeggio =
  \override Arpeggio.stencil =
  #(lambda (grob)
    (let* ((arp-dir (ly:grob-property grob 'arpeggio-direction))
           (arrow-glyph
             (format #f
               "scripts.arpeggio.arrow.~a1"
               (if (negative? arp-dir)
                   "M"
                   "")))
           (font (ly:grob-default-font grob))
           (arrow-head-stil (ly:font-get-glyph font arrow-glyph))
           (red-arrow
             (ly:stencil-scale (stencil-with-color arrow-head-stil
red) 1.5 1.5))
           (red-arrow-y-ext (ly:stencil-extent red-arrow Y))
           (red-arrow-x-ext (ly:stencil-extent red-arrow X)))

      (ly:grob-set-property! grob 'arpeggio-direction '())

      (let* ((stil (ly:arpeggio::print grob))
             (stil-y-ext (ly:stencil-extent stil Y))
             (stil-x-ext (ly:stencil-extent stil X)))
        (ly:stencil-add
          (ly:stencil-translate
            red-arrow
            (if (negative? arp-dir)
                (cons
                 (/
                  (- (interval-length stil-x-ext)
                     (interval-length red-arrow-x-ext)
                     )
                  2)
                  (- (car stil-y-ext) (interval-length red-arrow-y-ext)))
                (cons
                 (/
                  (- (interval-length stil-x-ext)
                     (interval-length red-arrow-x-ext)
                     )
                  2)
                  (cdr stil-y-ext))))
          stil))))

{
  \arpeggioArrowUp
  \myArpeggio
  <b d' f' b'>\arpeggio


  \arpeggioArrowDown
  \myArpeggio
  <b d' f' b'>\arpeggio
}

TODO
- remove the color
- probably transform the override into a music-function, then the now hardcoded
  scaling value is more conveniant settable.

Shouldn't be hard from here, please ask if something isn't clear.

Ofcourse you need to test all with real world examples. Some bugs may
raise their head...

NB if the scaling value is too high, then the output will be always poor.
If you really need a huge arrow-head, we would need to construct it
from scratch, not looking into the font.


Tutorial closed for now lol

Best,
  Harm