Re: drawing glissando line with (gliss) as text across line

[Thomas Morley]

2016-06-23 0:44 GMT+02:00 Thomas Morley <address@hidden>:
> 2016-06-22 23:48 GMT+02:00 Ryan Michael <address@hidden>:
>> Interesting. your example works perfectly in itself. But when I port it over
>> to my score I get the following error:
>>
>>  Wrong type argument in position 1 (expecting Stencil): ()
>>
>> I believe it calls it on this line:
>>
>>      (spanner-stencil-x-length (interval-length (ly:stencil-extent
>> spanner-stencil X)))
>>
>> Here is a gist of the score:
>> https://gist.github.com/ebbnormal/62a8893942a5e6f91735afdf77f2081a
>> I basically make a simple call to \glissandoTextOn as you do before I use
>> \glissando.
>>
>> Any ideas?
>
>
> If the glissando-line is _too_ short in tight layout-situations, it
> will not be printed. Thus no stencil, causing the error.
> Ensuring a reasonable minimum-length, cures the error, but the visual
> output is not convincing.
> Lemme see if I can come up with something better, but I'll likely have
> not no time to work on it before the weekend.
>
> Sorry,
>   Harm

Hi Ryan,

below next try.
I'm not really convinced though, see REMARK

\version "2.19.44"

%% REMARK
%% The code below keeps the default glissando-stencil, while adding some
%% text to it. This means the text-stencil needs to be rotated to match the
%% glissando; also some reasonable padding between them needs to be found.
%% It turned out being a pretty difficult task to do so with reasonable
%% exactness and the current code is not always convincing, although usable.
%%
%% TODO
%% Test whether constructing a glissando+text-stencil from scratch causes better
%% results

#(define (radians->degree radians)
  (/ (* radians 180) PI))

#(define (sign x)
  (if (= x 0)
      0
      (if (< x 0) -1 1)))

#(define ((gliss-plus-text text) grob)
  (if (not (ly:stencil? (ly:line-spanner::print grob)))
      #f
      (let* ((sys (ly:grob-system grob))
             (layout (ly:grob-layout grob))
             (line-thickness (ly:output-def-lookup layout 'line-thickness))
             (blot-diameter (ly:output-def-lookup layout 'blot-diameter))
             (thickness (ly:grob-property grob 'thickness))
             (thick
               (if (number? thickness)
                   (/ thickness 10)
                   line-thickness))
             (spanner-stencil (ly:line-spanner::print grob))
             (left-bound-info (ly:grob-property grob 'left-bound-info))
             (y-left (assoc-get 'Y left-bound-info))
             (x-left (assoc-get 'X left-bound-info))
             (left-padding (assoc-get 'padding left-bound-info))
             (right-bound-info (ly:grob-property grob 'right-bound-info))
             (y-right (assoc-get 'Y right-bound-info))
             (x-right (assoc-get 'X right-bound-info))
             (right-padding (assoc-get 'padding right-bound-info))
             (slant (sign (- y-right y-left)))
             (spanner-stencil-x-length
               (interval-length (ly:stencil-extent spanner-stencil X)))
             (spanner-stencil-y-length
               (interval-length (ly:stencil-extent spanner-stencil Y)))
             ;; TODO
             ;; fiddling around with PI and radians causes some inexactness
             (alpha
               (radians->degree
                 (- (/ PI 2)
                    (angle
                      (make-rectangular
                        (- spanner-stencil-y-length
                           (/ (+ thick blot-diameter) 2))
                        (- spanner-stencil-x-length
                           (/ (+ thick blot-diameter) 2)))))))
             (spanner-center-X
               (interval-center (ly:stencil-extent spanner-stencil X)))
             (text-stencil (grob-interpret-markup grob text))
             (rotated-text-stil
               (ly:stencil-rotate text-stencil (* slant alpha) 0 0))
             (text-center-X
               (interval-center (ly:stencil-extent rotated-text-stil X)))
             (translated-text-stencil
               (ly:stencil-translate
                 rotated-text-stil
                 ;; TODO
                 ;; some correcting values found by try and error
                 ;; how to calculate?
                 (cons
                   (+
                     (/ (+ left-padding right-padding) 2)
                     (- spanner-center-X text-center-X)
                     (if (negative? slant) 0.1 -0.6))
                   (+ (/ (+ y-right y-left) 2)
                      (if (negative? slant) 0.5 0.6))))))
      (ly:stencil-add
        spanner-stencil
        translated-text-stencil))))


glissandoTextOn = {
\temporary \override Score.Glissando.springs-and-rods =
  #ly:spanner::set-spacing-rods
\temporary \override Score.Glissando.minimum-length = 7
\temporary \override Score.Glissando #'stencil =
  #(gliss-plus-text
    ;(markup #:with-color red #:box #:italic #:fontsize -5 "gliss.")
    #{
      \markup \italic \fontsize #-5 "gliss."
    #})
}

glissandoTextOff = \revert Score.Glissando #'stencil


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXAMPLE
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\new Staff
  \relative g'' {
    \glissandoTextOn
    %\override Glissando.thickness = 5
    $@(map
      (lambda (n)
        #{
          \override Glissando.extra-dy = #n
          g4\glissando ges
          %\bar "" \break
        #})
      (iota 14 -7 1))
    $@(map
      (lambda (n)
        #{
          \override Glissando.extra-dy = #n
          g4..\glissando g16
          %\bar "" \break
        #})
      (iota 14 -7 1))
    \override Score.Glissando.breakable = ##t
    \override Score.Glissando.after-line-breaking = ##t
    \revert Glissando.extra-dy
    \bar "" \break
    g1\glissando
    \break
    <>^"Glissando at line-break is not really supported"
    ges,
  }

Anyway, hth,
  Harm