Re: Flat flags

[Thomas Morley]

2013/10/1 Gilberto Agostinho <address@hidden>:
> Hi all,
>
> According to the manual, the command necessary to create flat flags (\set
> stemLeftBeamCount) is "always equivalent to \once \set. In other words, beam
> count settings are not “sticky” [...]". Does this mean that the only way I
> can produce a score such as the one below is to use a \set stemLeftBeamCount
> for each single pitch?
>
> Also, does anyone knows how to generate grace notes with a flat flag as
> well? (After so many questions of mine on this mailing list, some of you
> might be thinking I have some psychotic fixation on grace notes)
>
> \version "2.17.26"
>
> {
>
>   \relative c' {
>
>     \set stemLeftBeamCount = #0 f16[] r8.
>
>     \set stemLeftBeamCount = #0 e16[]
>
>     \set stemLeftBeamCount = #0 gis16[] r8
>
>     \set stemLeftBeamCount = #0 fis[]
>
>     \set stemLeftBeamCount = #0 a32[] r64
>
>     \set stemLeftBeamCount = #0 f64[] r16
>
>     \grace{c8}
>
>     \set stemLeftBeamCount = #0 ees8[] r8
>
>   }
>
> }
>
>
> If this is too much headache, I will just keep using \override Flag
> #'stencil = #modern-straight-flag which is close enough to what I want.
>
>
> Thanks a lot for all the help. Regards,
>
> Gilberto



Hi Gilberto,

modern-straight-flag etc is defined in flag-styles.scm

It's a pity that the main definition there uses
'ly:round-filled-polygon'. Setting the points of the polygon to fit a
cuboid will result in inclined flags, perhaps a rounding issue.
If it would work this way it would be a two-liner to define flat flags.

I had to change ly:round-filled-polygon to ly:round-filled-box.
Though, now the whole definitions of straight-flag and buildflag have
to be present in file:

\version "2.17.26"

#(define (buildflag flag-stencil remain curr-stencil spacing)
  (if (> remain 0)
      (let* ((translated-stencil (ly:stencil-translate-axis
curr-stencil spacing Y))
             (new-stencil (ly:stencil-add flag-stencil translated-stencil)))
        (buildflag new-stencil (- remain 1) translated-stencil spacing))
      flag-stencil))

#(define-public (straight-flag flag-thickness flag-spacing
                              upflag-angle upflag-length
                              downflag-angle downflag-length)
  (lambda (grob)
    (let* ((stem-grob (ly:grob-parent grob X))
           (log (ly:grob-property stem-grob 'duration-log))
           (dir (ly:grob-property stem-grob 'direction))
           (stem-up (eqv? dir UP))
           (layout (ly:grob-layout grob))
           ;; scale with the note size (e.g. for grace notes)
           (factor (magstep (ly:grob-property grob 'font-size 0)))
           (grob-stem-thickness (ly:grob-property stem-grob 'thickness))
           (line-thickness (ly:output-def-lookup layout 'line-thickness))
           (half-stem-thickness (/ (* grob-stem-thickness line-thickness) 2))
           (raw-length (if stem-up upflag-length downflag-length))
           (angle (if stem-up upflag-angle downflag-angle))
           (flag-length (+ (* raw-length factor) half-stem-thickness))
           (flag-end (polar->rectangular flag-length angle))
           (thickness (* flag-thickness factor))
           (thickness-offset (cons 0 (* -1 thickness dir)))
           (spacing (* -1 flag-spacing factor dir ))
           (start (cons (- half-stem-thickness) (* half-stem-thickness dir)))
           ;; The points of a round-filled-polygon need to be given in clockwise
           ;; order, otherwise the polygon will be enlarged by blot-size*2!
           (points (if stem-up (list start flag-end
                                     (offset-add flag-end thickness-offset)
                                     (offset-add start thickness-offset))
                       (list start
                             (offset-add start thickness-offset)
                             (offset-add flag-end thickness-offset)
                             flag-end)))
           ;(stencil (ly:round-filled-polygon points half-stem-thickness))

           (stencil
             (ly:round-filled-box
               (ordered-cons (caar points) (caaddr points))
               (ordered-cons (cdar points) (cdaddr points))
               half-stem-thickness))
           ;; Log for 1/8 is 3, so we need to subtract 3
           (flag-stencil (buildflag stencil (- log 3) stencil spacing))
           (stroke-style (ly:grob-property grob 'stroke-style)))


      (if (equal? stroke-style "grace")
          (add-stroke-straight flag-stencil grob
                               dir log
                               stroke-style
                               flag-end flag-length
                               thickness
                               (* half-stem-thickness 2))
          flag-stencil))))

#(define-public (flat-flag grob)
  ((straight-flag 0.41 0.8 0 1.0 0 1.0) grob))

\version "2.17.26"

{

  \relative c' {
    \autoBeamOff
    \override Flag.stencil = #flat-flag
    f16 r8.
    e16
    gis16 r8
    fis
    a32 r64
    f64 r16
    \grace{c8}
    ees8 r8
  }
}


HTH,
  Harm