Re: Feature request: Display bezier control-points

[Urs Liska]

Am 04.05.2012 03:09, schrieb Thomas Morley:
> Hi Urs,
>
> > I would be very happy about one or two more features (that I unfortunately
> > can't implement myself:
> > - highlight (and separate from the music) the crosses through a color
> > - possibly adding a connecting (very thin) line, making it even more
> > intuitive
> >
> > Best
> > Urs
> how about:
>
> \version "2.14.2"
>
> #(define (make-cross-stencil coords)
>   (ly:stencil-add
>     (make-line-stencil 0.1 (- (car coords) 0.2) (- (cdr coords) 0.2)
>    (+ (car coords) 0.2) (+ (cdr coords) 0.2))
>     (make-line-stencil 0.1 (- (car coords) 0.2) (+ (cdr coords) 0.2)
>    (+ (car coords) 0.2) (- (cdr coords) 0.2))))
>
> #(define (display-control-points line)
>   (lambda (grob)
>     (let ((stencil (ly:slur::print grob))
>           (cps (ly:grob-property grob 'control-points)))
>
>     (ly:stencil-add stencil
>       (ly:stencil-in-color
>           (make-cross-stencil (second cps))
>           1 0 0)
>       (ly:stencil-in-color
>           (make-cross-stencil (third cps))
>           1 0 0)
>       (if (eq? line #t)
>           (make-line-stencil 0.05 (car (second cps)) (cdr (second cps))
> (car (third cps))  (cdr (third cps)))
>           empty-stencil)
>       )
>       )))
>
> \relative c'' {
>   \override Slur #'stencil = #(display-control-points #t)
>   c2( d e f)
> }
>
>
> HTH,
>    Harm
Hi Harm,

thanks for this.
What I had in mind was to draw lines from control-points 1-2 and 3-4 (as 
in drawing programs).
Your solution is equally intuitive, but I have the impression that 'my' 
lines are generally smaller and therefore less intrusive, especially 
with longer curves.

See the attached updated file.
In it you can see also:
- it equally works with broken slurs
- the lines are important: Take the control-point 2 of the slur in m. 2. 
It is already hard to tell if this belongs to the first or the second 
line - an ambiguity that isn't present in the second version with the lines.

There are two more issues with this:
- I don't see how to get it working with ties. Which would be nice of course
- It would be nice to be able to pass the color as a (optional) list of 
values. So one could store the main function in a library file and 
define the appearance in a 'user space' wrapper function (like in the 
attached file). And it would make it possible to differentiate colors 
for slurs, phrasingSlurs and Ties.

If we could continue to get a set of working tools (together with 
David's shapeXXX functions), I'd try hard to find the time to document 
it in some kind of tutorial (although currently I have to finish the 
'real-life' project I need all this for ...)

Best
Urs

displayControlPoints_ver_II.ily
Description: Text document