From 1a788358cd2d55e1d8f7556861e984f94c1ce2e9 Mon Sep 17 00:00:00 2001
From: Carl Sorensen <c_sorensen@byu.edu>
Date: Sun, 29 Mar 2009 22:52:45 -0600
Subject: [PATCH] Refactor fret diagrams for simpler calls (cherry picked from
 commit 50a92f3105120599c5204f85bf6c3d81ef51ac50)

---
 scm/fret-diagrams.scm | 1037 ++++++++++++++++++++---------------------
 1 file changed, 502 insertions(+), 535 deletions(-)

diff --git a/scm/fret-diagrams.scm b/scm/fret-diagrams.scm
index 0bf9d6bda7..70390d2314 100644
--- a/scm/fret-diagrams.scm
+++ b/scm/fret-diagrams.scm
@@ -8,7 +8,7 @@
 ;  Utility functions
 ;
 ;
-    
+
 (define (string-x-extent start-point end-point)
   "Return the x-extent of a string that goes from start-point
 to end-point."
@@ -67,48 +67,6 @@ to end-point."
                          (third this-list)))
                (subtract-base-fret base-fret (cdr dot-list))))))
 
-(define (make-bezier-sandwich-list start stop base height 
-         half-thickness orientation)
-  "Make the argument list for a bezier sandwich from
-string coordinate @var{start} to string-coordinate @var{stop} with a 
-baseline at fret coordinate @var{base}, a height of
-@var{height}, and a half thickness of @var{half-thickness}."
-  (let* ((width (+ (- stop start) 1))
-         (cp-left-width (+ (* width half-thickness) start))
-         (cp-right-width (- stop (* width half-thickness)))
-         (bottom-control-point-height 
-           (- base (- height half-thickness)))
-         (top-control-point-height
-           (- base height))
-         (left-end-point 
-          (stencil-coordinates base start orientation))
-         (right-end-point
-          (stencil-coordinates base stop orientation))
-         (left-upper-control-point
-          (stencil-coordinates 
-            top-control-point-height cp-left-width orientation))
-         (left-lower-control-point
-          (stencil-coordinates 
-            bottom-control-point-height cp-left-width orientation))
-         (right-upper-control-point
-          (stencil-coordinates 
-            top-control-point-height cp-right-width orientation))
-         (right-lower-control-point
-          (stencil-coordinates 
-            bottom-control-point-height cp-right-width orientation)))
-    ; order of bezier control points is:
-    ;    left cp low, right cp low, right end low, left end low
-    ;    right cp high, left cp high, left end high, right end high.
-    ;
-   (list left-lower-control-point
-         right-lower-control-point
-         right-end-point
-         left-end-point
-         right-upper-control-point
-         left-upper-control-point
-         left-end-point
-         right-end-point)))
-
 (define (drop-paren item-list)
   "Drop a final parentheses from a fret indication list
 @code{item-list} resulting from a terse string specification of barre."
@@ -154,7 +112,7 @@ found."
 ;
 ;  Conversions between fret/string coordinate system and x-y coordinate
 ;  system.
-;  
+;
 ;  Fret coordinates are measured down the fretboard from the nut,
 ;   starting at 0.
 ;
@@ -171,7 +129,7 @@ found."
    (cons (- (cdr extent)) (- (car extent))))
 
 (define (stencil-fretboard-extent stencil fretboard-axis orientation)
-  "Return the extent of @code{stencil} in the @code{fretboard-axis} 
+  "Return the extent of @code{stencil} in the @code{fretboard-axis}
 direction."
   (if (eq? fretboard-axis 'fret)
   (cond ((eq? orientation 'landscape)
@@ -192,23 +150,13 @@ direction."
 (define (stencil-fretboard-offset stencil fretboard-axis orientation)
  "Return a the stencil coordinates of the center of @code{stencil}
 in the @code{fretboard-axis} direction."
-  (* 0.5 (interval-length 
+  (* 0.5 (interval-length
            (stencil-fretboard-extent stencil fretboard-axis orientation))))
 
-(define (stencil-coordinates fret-coordinate string-coordinate orientation)
- "Return a pair @code{(x-coordinate . y-coordinate)} in stencil coordinate 
-system."
-  (cond
-   ((eq? orientation 'landscape)
-    (cons fret-coordinate string-coordinate))
-   ((eq? orientation 'opposing-landscape)
-    (cons (- fret-coordinate) (- string-coordinate)))
-   (else
-    (cons string-coordinate (- fret-coordinate)))))
- 
+
 (define (string-thickness string thickness-factor)
   (expt (1+ thickness-factor) (1- string)))
-  
+
 ;
 ;  Functions that create stencils used in the fret diagram
 ;
@@ -222,404 +170,6 @@ with magnification @var{mag} of the string @var{text}."
            (prepend-alist-chain 'font-family 'sans props))))
     (interpret-markup layout my-props text)))
 
-
-(define (string-stencil string string-count fret-range
-                        th thickness-factor size orientation)
- "Make a stencil for @code{string}, given the fret-diagram
-overall parameters."
-  (let* ((string-coordinate (- string-count string))
-         (current-string-thickness 
-           (* th size (string-thickness string thickness-factor)))
-         (fret-half-thickness (* size th 0.5))
-         (half-string (* current-string-thickness 0.5))
-         (start-coordinates
-           (stencil-coordinates
-             (- fret-half-thickness)
-             (- (* size string-coordinate) half-string)
-             orientation))
-         (end-coordinates
-           (stencil-coordinates
-            (+ fret-half-thickness (* size (1+ (fret-count fret-range))))
-            (+ half-string (* size string-coordinate))
-            orientation)))
-   (ly:round-filled-box (string-x-extent start-coordinates end-coordinates)
-                        (string-y-extent start-coordinates end-coordinates)
-                        (* th size))))
-   
-(define (fret-stencil fret string-count th 
-                      thickness-factor size orientation)
- "Make a stencil for @code{fret}, given the fret-diagram overall parameters."
- (let* ((low-string-half-thickness 
-          (* 0.5 size th (string-thickness string-count thickness-factor)))
-        (fret-half-thickness (* 0.5 size th)) 
-        (start-coordinates 
-         (stencil-coordinates
-           (* size fret)
-           (- fret-half-thickness low-string-half-thickness)
-           orientation))
-        (end-coordinates
-         (stencil-coordinates
-          (* size fret)
-          (* size (1- string-count))
-          orientation)))
-  (make-line-stencil
-   (* size th)
-   (car start-coordinates) (cdr start-coordinates)
-   (car end-coordinates) (cdr end-coordinates))))
-
-(define (make-straight-barre-stencil 
-          size half-thickness fret-coordinate
-          start-string-coordinate end-string-coordinate orientation)
-  "Create a straight barre stencil."
-  (let ((start-point 
-         (stencil-coordinates
-          (* size fret-coordinate)
-          (* size start-string-coordinate)
-          orientation))
-        (end-point
-         (stencil-coordinates
-          (* size fret-coordinate)
-          (* size end-string-coordinate)
-          orientation)))
-   (make-line-stencil
-     half-thickness
-     (car start-point)
-     (cdr start-point)
-     (car end-point)
-     (cdr end-point))))
-
-(define (make-curved-barre-stencil 
-          size half-thickness fret-coordinate
-          start-string-coordinate end-string-coordinate orientation)
-  "Create a curved barre stencil."
-  (let* ((bezier-thick 0.1)
-         (bezier-height 0.5)
-         (bezier-list 
-           (make-bezier-sandwich-list
-            (* size start-string-coordinate)
-            (* size end-string-coordinate)
-            (* size fret-coordinate)
-            (* size bezier-height)
-            (* size bezier-thick)
-            orientation))
-         (box-lower-left
-          (stencil-coordinates 
-           (+ (* size fret-coordinate) half-thickness)
-           (- (* size start-string-coordinate) half-thickness)
-           orientation))
-         (box-upper-right
-          (stencil-coordinates
-           (- (* size fret-coordinate) (* size bezier-height) half-thickness)
-           (+ (* size end-string-coordinate) half-thickness)
-           orientation))
-         (x-extent (cons (car box-lower-left) (car box-upper-right)))
-         (y-extent (cons (cdr box-lower-left) (cdr box-upper-right))))
-    (ly:make-stencil
-      (list 'bezier-sandwich
-            `(quote ,bezier-list)
-            (* size bezier-thick))
-      x-extent
-      y-extent)))
-
-
-;
-;
-;  Functions used to draw fret-diagram elements
-;
-;
-
-(define (draw-strings string-count fret-range th 
-                      thickness-factor size orientation)
-  "Draw the string lines for a fret diagram with
-@var{string-count} strings and frets as indicated in @var{fret-range}.
-Line thickness is given by @var{th}, fret & string spacing by
-@var{size}.  Orientation is determined by @var{orientation}. "
-
-  (define (helper x)
-     (if (null? (cdr x))
-         (string-stencil 
-          (car x) string-count fret-range th
-          thickness-factor size orientation)
-         (ly:stencil-add 
-           (string-stencil 
-            (car x) string-count fret-range th
-            thickness-factor size orientation)
-           (helper (cdr x)))))
-
-  (let* ( (string-list (map 1+ (iota string-count))))
-   (helper string-list)))
-
-(define (draw-fret-lines fret-count string-count th 
-                         thickness-factor size orientation)
-  "Draw @var{fret-count} fret lines for a fret diagram
-with @var{string-count} strings.  Line thickness is given by @var{th},
-fret & string spacing by @var{size}. Orientation is given by @var{orientation}"
-  (define (helper x)
-     (if (null? (cdr x))
-         (fret-stencil 
-          (car x) string-count th thickness-factor
-           size orientation)
-         (ly:stencil-add 
-           (fret-stencil 
-            (car x) string-count th thickness-factor
-            size orientation)
-           (helper (cdr x)))))
-
-  (let* ( (fret-list (iota (1+ fret-count))))
-   (helper fret-list)))
-
-(define (draw-thick-zero-fret details string-count th 
-                              thickness-factor size orientation)
-  "Draw a thick zeroth fret for a fret diagram whose base fret is 1."
-  (let* ((sth (* th size))
-         (half-lowest-string-thickness 
-           (* 0.5 th (string-thickness string-count thickness-factor))) 
-         (half-thick (* 0.5 sth))
-         (top-fret-thick
-           (* sth (assoc-get 'top-fret-thickness details 3.0)))
-         (start-string-coordinate (- half-lowest-string-thickness))
-         (end-string-coordinate (+ (* size (1- string-count)) half-thick))
-         (start-fret-coordinate half-thick)
-         (end-fret-coordinate (- half-thick top-fret-thick))
-         (lower-left 
-          (stencil-coordinates 
-            start-fret-coordinate start-string-coordinate orientation))
-         (upper-right 
-          (stencil-coordinates 
-            end-fret-coordinate end-string-coordinate orientation)))
-   (ly:round-filled-box 
-     (cons (car lower-left) (car upper-right))
-     (cons (cdr lower-left) (cdr upper-right))
-     sth)))
-  
-
-(define (draw-capo details string-count fret fret-count th size 
-                   dot-pos orientation)
-  "Draw a capo indicator across the full width of the fret-board
-at @var{fret}."
-(let* ((capo-thick
-         (* size (assoc-get 'capo-thickness details 0.5)))
-       (half-thick (* capo-thick 0.5))
-       (last-string-pos 0)
-       (first-string-pos (* size (- string-count 1)))
-       (fret-pos ( * size (1- (+ dot-pos fret))))
-       (start-point 
-         (stencil-coordinates fret-pos first-string-pos orientation))
-       (end-point 
-         (stencil-coordinates fret-pos last-string-pos orientation)))
-  (make-line-stencil
-     capo-thick 
-     (car start-point) (cdr start-point)
-     (car end-point) (cdr end-point))))
-
-(define (draw-frets fret-range string-count th 
-                    thickness-factor size orientation)
-  "Draw the fret lines for a fret diagram with
-@var{string-count} strings and frets as indicated in @var{fret-range}.
-Line thickness is given by @var{th}, fret & string spacing by
-@var{size}. Orientation is given by @var{orientation}."
-  (let* ((my-fret-count (fret-count fret-range)))
-   (draw-fret-lines 
-     my-fret-count string-count th thickness-factor size orientation)))
-
-(define (draw-dots layout props string-count fret-count
-                   size finger-code
-                   dot-position dot-radius dot-thickness dot-list orientation)
-  "Make dots for fret diagram."
-
-  (let* ((details (merge-details 'fret-diagram-details props '()))
-         (scale-dot-radius (* size dot-radius))
-         (scale-dot-thick (* size dot-thickness))
-         (dot-color (assoc-get 'dot-color details 'black))
-         (finger-label-padding 0.3)
-         (dot-label-font-mag
-           (* scale-dot-radius (assoc-get 'dot-label-font-mag details 1.0)))
-         (string-label-font-mag
-           (* size 
-             (assoc-get 'string-label-font-mag details 
-                        (cond ((or (eq? orientation 'landscape)
-                                   (eq? orientation 'opposing-landscape))
-                               0.5)
-                              (else  0.6)))))
-         (mypair (car dot-list))
-         (restlist (cdr dot-list))
-         (string (car mypair))
-         (fret (cadr mypair))
-         (fret-coordinate (* size (+ (1- fret) dot-position)))
-         (string-coordinate (* size (- string-count string)))
-         (dot-coordinates 
-          (stencil-coordinates fret-coordinate string-coordinate orientation))
-         (extent (cons (- scale-dot-radius) scale-dot-radius))
-         (finger (caddr mypair))
-         (finger (if (number? finger) (number->string finger) finger))
-         (dot-stencil (if (eq? dot-color 'white)
-                       (ly:stencil-add
-                         (make-circle-stencil
-                           scale-dot-radius scale-dot-thick #t)
-                         (ly:stencil-in-color
-                           (make-circle-stencil
-                             (- scale-dot-radius (* 0.5 scale-dot-thick))
-                             0  #t)
-                           1 1 1))
-                       (make-circle-stencil
-                         scale-dot-radius scale-dot-thick #t)))
-         (positioned-dot (ly:stencil-translate dot-stencil dot-coordinates))
-         (labeled-dot-stencil 
-           (cond 
-             ((or (eq? finger '())(eq? finger-code 'none))
-              positioned-dot)
-             ((eq? finger-code 'in-dot)
-              (let ((finger-label 
-                     (centered-stencil
-                       (sans-serif-stencil
-                         layout props dot-label-font-mag finger))))
-              (ly:stencil-translate
-                (ly:stencil-add
-                  dot-stencil
-                  (if (eq? dot-color 'white)
-                      finger-label
-                      (ly:stencil-in-color finger-label 1 1 1)))
-                dot-coordinates)))
-             ((eq? finger-code 'below-string)
-              (let* ((label-stencil 
-                       (centered-stencil 
-                         (sans-serif-stencil
-                           layout props string-label-font-mag
-                           finger)))
-                     (label-fret-offset
-                       (stencil-fretboard-offset 
-                         label-stencil 'fret orientation))
-                     (label-fret-coordinate 
-                       (+ (* size (+ 1 fret-count finger-label-padding))
-                          label-fret-offset))
-                     (label-string-coordinate string-coordinate)
-                     (label-translation 
-                       (stencil-coordinates 
-                         label-fret-coordinate
-                         label-string-coordinate
-                         orientation)))
-                (ly:stencil-add
-                  positioned-dot
-                  (ly:stencil-translate label-stencil label-translation))))
-             (else ;unknown finger-code
-               positioned-dot))))
-    (if (null? restlist)
-      labeled-dot-stencil
-      (ly:stencil-add
-        (draw-dots
-          layout props string-count fret-count size finger-code
-          dot-position dot-radius dot-thickness restlist orientation)
-        labeled-dot-stencil))))
-
-(define (draw-xo 
-          layout props string-count fret-range size xo-list orientation)
-  "Put open and mute string indications on diagram, as contained in
-@var{xo-list}."
-  (let* ((details (merge-details 'fret-diagram-details props '()))
-         (xo-font-mag
-           (* size (assoc-get 
-                    'xo-font-magnification details 
-                    (cond ((or (eq? orientation 'landscape)
-                            (eq? orientation 'opposing-landscape))
-                           0.4)
-                     (else 0.4)))))
-         (mypair (car xo-list))
-         (restlist (cdr xo-list))
-         (glyph-string (if (eq? (car mypair) 'mute)
-                         (assoc-get 'mute-string details "X")
-                         (assoc-get 'open-string details "O")))
-         (glyph-string-coordinate (* (- string-count (cadr mypair)) size))
-         (glyph-stencil 
-           (centered-stencil
-             (sans-serif-stencil 
-               layout props (* size xo-font-mag) glyph-string)))
-         (glyph-stencil-coordinates 
-           (stencil-coordinates 0 glyph-string-coordinate orientation))
-         (positioned-glyph
-           (ly:stencil-translate glyph-stencil glyph-stencil-coordinates)))
-    (if (null? restlist)
-        positioned-glyph
-        (ly:stencil-add
-         (draw-xo
-          layout props string-count fret-range size restlist orientation)
-         positioned-glyph))))
-
-(define (draw-barre layout props string-count fret-range
-                    size finger-code dot-position dot-radius
-                    barre-list orientation)
-  "Create barre indications for a fret diagram"
-  (if (not (null? barre-list))
-    (let* ((details (merge-details 'fret-diagram-details props '()))
-           (string1 (caar barre-list))
-           (string2 (cadar barre-list))
-           (barre-fret (caddar barre-list))
-           (top-fret (cdr fret-range))
-           (low-fret (car fret-range))
-           (fret (1+ (- barre-fret low-fret)))
-           (barre-vertical-offset 0.5)
-           (dot-center-fret-coordinate (+ (1- fret) dot-position))
-           (barre-fret-coordinate
-             (+ dot-center-fret-coordinate
-                (* (- barre-vertical-offset 0.5) dot-radius)))
-           (barre-start-string-coordinate (- string-count string1))
-           (barre-end-string-coordinate (- string-count string2))
-           (scale-dot-radius (* size dot-radius))
-           (barre-type (assoc-get 'barre-type details 'curved))
-           (barre-stencil
-             (cond 
-               ((eq? barre-type 'straight)
-                (make-straight-barre-stencil 
-                  size scale-dot-radius 
-                  barre-fret-coordinate barre-start-string-coordinate
-                  barre-end-string-coordinate orientation))
-               ((eq? barre-type 'curved)
-                (make-curved-barre-stencil 
-                  size scale-dot-radius
-                  barre-fret-coordinate barre-start-string-coordinate
-                  barre-end-string-coordinate orientation)))))
-      (if (not (null? (cdr barre-list)))
-        (ly:stencil-add
-          barre-stencil
-          (draw-barre layout props string-count fret-range size finger-code
-                      dot-position dot-radius (cdr barre-list) orientation))
-        barre-stencil ))))
-
-(define (label-fret layout props string-count fret-range size orientation)
-  "Label the base fret on a fret diagram"
-  (let* ((details (merge-details 'fret-diagram-details props '()))
-         (base-fret (car fret-range))
-         (label-font-mag (assoc-get 'fret-label-font-mag details 0.5))
-         (label-space (* 0.5 size))
-         (label-dir (assoc-get 'label-dir details RIGHT))
-         (label-vertical-offset
-           (assoc-get 'fret-label-vertical-offset details 0))
-         (number-type
-           (assoc-get 'number-type details 'roman-lower))
-         (label-text
-           (cond
-             ((equal? number-type 'roman-lower)
-              (fancy-format #f "~(~@r~)" base-fret))
-             ((equal? number-type 'roman-upper)
-              (fancy-format #f "~@r" base-fret))
-             ((equal? 'arabic number-type)
-              (fancy-format #f "~d" base-fret))
-             (else (fancy-format #f "~(~@r~)" base-fret))))
-         (label-stencil
-           (centered-stencil
-             (sans-serif-stencil 
-               layout props (* size label-font-mag) label-text)))
-         (label-half-width 
-           (stencil-fretboard-offset label-stencil 'string orientation))
-         (label-outside-diagram (+ label-space label-half-width)))
-    (ly:stencil-translate
-      label-stencil
-      (stencil-coordinates 
-        (1+ (* size label-vertical-offset))
-        (if (eq? label-dir LEFT)
-            (- label-outside-diagram)
-            (+ (* size (1- string-count)) label-outside-diagram))
-        orientation))))
-
 ;;
 ;;
 ;;  markup commands and associated functions
@@ -649,7 +199,7 @@ Line thickness is given by @var{th}, fret & string spacing by
               (set! dot-list (cons* (cdr my-item) dot-list))))
             (parse-item (cdr mylist)))))
     ;; calculate fret-range
-    (let ((maxfret 0) 
+    (let ((maxfret 0)
           (minfret (if (> capo-fret 0) capo-fret 99)))
       (let updatemax ((fret-list dot-list))  ;CHANGE THIS TO HELPER FUNCTION?
         (if (null? fret-list)
@@ -669,7 +219,7 @@ Line thickness is given by @var{th}, fret & string spacing by
     (acons 'fret-range fret-range
            (acons 'barre-list barre-list
                   (acons 'dot-list dot-list
-                         (acons 'xo-list xo-list 
+                         (acons 'xo-list xo-list
                                 (acons 'capo-fret capo-fret '())))))))
 
 (define (make-fret-diagram layout props marking-list)
@@ -680,41 +230,42 @@ Line thickness is given by @var{th}, fret & string spacing by
          ; called from this routine.  If they're only used in one of the
          ; sub-procedure, they're obtained in that procedure
          (size (chain-assoc-get 'size props 1.0)) ; needed for everything
-;TODO -- get string-count directly from length of stringTunings;
-;         from FretBoard engraver, but not from markup call
+         ;TODO -- get string-count directly from length of stringTunings;
+         ;         from FretBoard engraver, but not from markup call
          (details (merge-details 'fret-diagram-details props '()))
          (string-count
-          (assoc-get 'string-count details 6)) ; needed for everything
+           (assoc-get 'string-count details 6)) ; needed for everything
          (my-fret-count
-          (assoc-get 'fret-count details 4)) ; needed for everything
+           (assoc-get 'fret-count details 4)) ; needed for everything
          (orientation
-          (assoc-get 'orientation details 'normal)) ; needed for everything
+           (assoc-get 'orientation details 'normal)) ; needed for everything
          (finger-code
-          (assoc-get
-           'finger-code details 'none)) ; needed for draw-dots and draw-barre
+           (assoc-get
+             'finger-code details 'none)) ; needed for draw-dots and draw-barre
          (default-dot-radius
            (if (eq? finger-code 'in-dot) 0.425 0.25)) ; bigger dots if labeled
          (default-dot-position
            (if (eq? finger-code 'in-dot)
-               (- 0.95 default-dot-radius)
-               0.6)) ; move up to make room for bigger if labeled
+             (- 0.95 default-dot-radius)
+             0.6)) ; move up to make room for bigger dot if labeled
          (dot-radius
-          (assoc-get
-           'dot-radius details default-dot-radius))  ; needed for draw-dots
-                                                     ; and draw-barre
+           (assoc-get
+             'dot-radius details default-dot-radius))  ; needed for draw-dots
+         ; and draw-barre
          (dot-position
-          (assoc-get
-           'dot-position details default-dot-position)) ; needed for draw-dots
-                                                        ; and draw-barre
+           (assoc-get
+             'dot-position details default-dot-position)) ; needed for draw-dots
+         ; and draw-barre
          (th
-          (* (ly:output-def-lookup layout 'line-thickness)
-             (chain-assoc-get 'thickness props 0.5))) ; needed for draw-frets
-                                                      ; and draw-strings
+           (* (ly:output-def-lookup layout 'line-thickness)
+              (chain-assoc-get 'thickness props 0.5))) ; needed for draw-frets
+         ; and draw-strings
+         (sth (* size th))
          (thickness-factor (assoc-get 'string-thickness-factor details 0))
          (alignment
-          (chain-assoc-get 'align-dir props -0.4)) ; needed only here
+           (chain-assoc-get 'align-dir props -0.4)) ; needed only here
          (xo-padding
-          (* size (assoc-get 'xo-padding details 0.2))) ; needed only here
+           (* size (assoc-get 'xo-padding details 0.2))) ; needed only here
          (parameters (fret-parse-marking-list marking-list my-fret-count))
          (capo-fret (assoc-get 'capo-fret parameters 0))
          (dot-list (cdr (assoc 'dot-list parameters)))
@@ -723,72 +274,488 @@ Line thickness is given by @var{th}, fret & string spacing by
          (my-fret-count (fret-count fret-range))
          (barre-list (cdr (assoc 'barre-list parameters)))
          (barre-type
-          (assoc-get 'barre-type details 'curved))
-         (fret-diagram-stencil
+           (assoc-get 'barre-type details 'curved))
+         (fret-diagram-stencil '()))
+    ;
+    ;;  Here are the fret diagram helper functions that depend on the
+    ;;  fret diagram parameters.  The functions are here because the
+    ;;  diagram parameters are part of the lexical scope here.
+
+    (define (stencil-coordinates fret-coordinate string-coordinate)
+      "Return a pair @code{(x-coordinate . y-coordinate)}
+      in stencil coordinate system."
+      (cond
+        ((eq? orientation 'landscape)
+         (cons fret-coordinate string-coordinate))
+        ((eq? orientation 'opposing-landscape)
+         (cons (- fret-coordinate) (- string-coordinate)))
+        (else
+          (cons string-coordinate (- fret-coordinate)))))
+
+    (define (make-bezier-sandwich-list start stop base height
+                                       half-thickness)
+      "Make the argument list for a bezier sandwich from
+string coordinate @var{start} to string-coordinate @var{stop} with a
+baseline at fret coordinate @var{base}, a height of
+@var{height}, and a half thickness of @var{half-thickness}."
+     (let* ((width (+ (- stop start) 1))
+           (cp-left-width (+ (* width half-thickness) start))
+           (cp-right-width (- stop (* width half-thickness)))
+           (bottom-control-point-height
+             (- base (- height half-thickness)))
+           (top-control-point-height
+             (- base height))
+           (left-end-point
+             (stencil-coordinates base start))
+           (right-end-point
+             (stencil-coordinates base stop))
+           (left-upper-control-point
+             (stencil-coordinates
+               top-control-point-height cp-left-width))
+           (left-lower-control-point
+             (stencil-coordinates
+               bottom-control-point-height cp-left-width))
+           (right-upper-control-point
+             (stencil-coordinates
+               top-control-point-height cp-right-width))
+           (right-lower-control-point
+             (stencil-coordinates
+               bottom-control-point-height cp-right-width)))
+      ; order of bezier control points is:
+      ;    left cp low, right cp low, right end low, left end low
+      ;    right cp high, left cp high, left end high, right end high.
+      ;
+      (list left-lower-control-point
+            right-lower-control-point
+            right-end-point
+            left-end-point
+            right-upper-control-point
+            left-upper-control-point
+            left-end-point
+            right-end-point)))
+
+    (define (draw-strings)
+      "Draw the string lines for a fret diagram with
+@var{string-count} strings and frets as indicated in @var{fret-range}.
+Line thickness is given by @var{th}, fret & string spacing by
+@var{size}.  Orientation is determined by @var{orientation}. "
+
+      (define (helper x)
+        (if (null? (cdr x))
+          (string-stencil (car x))
           (ly:stencil-add
-           (draw-strings 
-             string-count fret-range th thickness-factor size orientation)
-           (draw-frets 
-             fret-range string-count th thickness-factor size orientation))))
+            (string-stencil (car x))
+            (helper (cdr x)))))
+
+      (let* ( (string-list (map 1+ (iota string-count))))
+        (helper string-list)))
+
+    (define (string-stencil string)
+      "Make a stencil for @code{string}, given the fret-diagram
+      overall parameters."
+      (let* ((string-coordinate (- string-count string))
+             (current-string-thickness
+               (* th size (string-thickness string thickness-factor)))
+             (fret-half-thickness (* size th 0.5))
+             (half-string (* current-string-thickness 0.5))
+             (start-coordinates
+               (stencil-coordinates
+                 (- fret-half-thickness)
+                 (- (* size string-coordinate) half-string)))
+             (end-coordinates
+               (stencil-coordinates
+                 (+ fret-half-thickness (* size (1+ (fret-count fret-range))))
+                 (+ half-string (* size string-coordinate)))))
+        (ly:round-filled-box
+         (string-x-extent start-coordinates end-coordinates)
+         (string-y-extent start-coordinates end-coordinates)
+         (* th size))))
+
+    (define (draw-frets)
+      "Draw the fret lines for a fret diagram with
+@var{string-count} strings and frets as indicated in @var{fret-range}.
+Line thickness is given by @var{th}, fret & string spacing by
+@var{size}. Orientation is given by @var{orientation}."
+      (define (helper x)
+        (if (null? (cdr x))
+          (fret-stencil (car x))
+          (ly:stencil-add
+            (fret-stencil (car x))
+            (helper (cdr x)))))
+
+      (let ((fret-list (iota (1+ my-fret-count))))
+        (helper fret-list)))
+
+     (define (fret-stencil fret)
+        "Make a stencil for @code{fret}, given the
+fret-diagram overall parameters."
+       (let* ((low-string-half-thickness
+                (* 0.5
+                   size
+                   th
+                   (string-thickness string-count thickness-factor)))
+              (fret-half-thickness (* 0.5 size th))
+              (start-coordinates
+                (stencil-coordinates
+                  (* size fret)
+                  (- fret-half-thickness low-string-half-thickness)))
+              (end-coordinates
+                (stencil-coordinates
+                  (* size fret)
+                  (* size (1- string-count)))))
+         (make-line-stencil
+           (* size th)
+           (car start-coordinates) (cdr start-coordinates)
+           (car end-coordinates) (cdr end-coordinates))))
+
+     (define (draw-barre barre-list)
+       "Create barre indications for a fret diagram"
+       (if (not (null? barre-list))
+         (let* ((string1 (caar barre-list))
+                (string2 (cadar barre-list))
+                (barre-fret (caddar barre-list))
+                (top-fret (cdr fret-range))
+                (low-fret (car fret-range))
+                (fret (1+ (- barre-fret low-fret)))
+                (barre-vertical-offset 0.5)
+                (dot-center-fret-coordinate (+ (1- fret) dot-position))
+                (barre-fret-coordinate
+                  (+ dot-center-fret-coordinate
+                     (* (- barre-vertical-offset 0.5) dot-radius)))
+                (barre-start-string-coordinate (- string-count string1))
+                (barre-end-string-coordinate (- string-count string2))
+                (scale-dot-radius (* size dot-radius))
+                (barre-type (assoc-get 'barre-type details 'curved))
+                (barre-stencil
+                  (cond
+                    ((eq? barre-type 'straight)
+                     (make-straight-barre-stencil
+                       barre-fret-coordinate
+                       barre-start-string-coordinate
+                       barre-end-string-coordinate
+                       scale-dot-radius))
+                    ((eq? barre-type 'curved)
+                     (make-curved-barre-stencil
+                       barre-fret-coordinate
+                       barre-start-string-coordinate
+                       barre-end-string-coordinate
+                       scale-dot-radius)))))
+           (if (not (null? (cdr barre-list)))
+             (ly:stencil-add
+               barre-stencil
+               (draw-barre (cdr barre-list)))
+             barre-stencil ))))
+
+     (define (make-straight-barre-stencil
+               fret-coordinate
+               start-string-coordinate
+               end-string-coordinate
+               half-thickness)
+       "Create a straight barre stencil."
+       (let ((start-point
+               (stencil-coordinates
+                 (* size fret-coordinate)
+                 (* size start-string-coordinate)))
+             (end-point
+               (stencil-coordinates
+                 (* size fret-coordinate)
+                 (* size end-string-coordinate))))
+         (make-line-stencil
+           half-thickness
+           (car start-point)
+           (cdr start-point)
+           (car end-point)
+           (cdr end-point))))
+
+     (define (make-curved-barre-stencil
+               fret-coordinate
+               start-string-coordinate
+               end-string-coordinate
+               half-thickness)
+       "Create a curved barre stencil."
+       (let* ((bezier-thick 0.1)
+              (bezier-height 0.5)
+              (bezier-list
+                (make-bezier-sandwich-list
+                  (* size start-string-coordinate)
+                  (* size end-string-coordinate)
+                  (* size fret-coordinate)
+                  (* size bezier-height)
+                  (* size bezier-thick)))
+              (box-lower-left
+                (stencil-coordinates
+                  (+ (* size fret-coordinate) half-thickness)
+                  (- (* size start-string-coordinate) half-thickness)))
+              (box-upper-right
+                (stencil-coordinates
+                  (- (* size fret-coordinate)
+                     (* size bezier-height)
+                     half-thickness)
+                  (+ (* size end-string-coordinate) half-thickness)))
+              (x-extent (cons (car box-lower-left) (car box-upper-right)))
+              (y-extent (cons (cdr box-lower-left) (cdr box-upper-right))))
+         (ly:make-stencil
+           (list 'bezier-sandwich
+                 `(quote ,bezier-list)
+                 (* size bezier-thick))
+           x-extent
+           y-extent)))
+
+     (define (draw-dots dot-list)
+       "Make dots for fret diagram."
+
+       (let* ( (scale-dot-radius (* size dot-radius))
+              (scale-dot-thick (* size th))
+              (dot-color (assoc-get 'dot-color details 'black))
+              (finger-label-padding 0.3)
+              (dot-label-font-mag
+                (* scale-dot-radius
+                   (assoc-get 'dot-label-font-mag details 1.0)))
+              (string-label-font-mag
+                (* size
+                   (assoc-get
+                     'string-label-font-mag details
+                     (cond ((or (eq? orientation 'landscape)
+                                (eq? orientation 'opposing-landscape))
+                            0.5)
+                           (else  0.6)))))
+              (mypair (car dot-list))
+              (restlist (cdr dot-list))
+              (string (car mypair))
+              (fret (cadr mypair))
+              (fret-coordinate (* size (+ (1- fret) dot-position)))
+              (string-coordinate (* size (- string-count string)))
+              (dot-coordinates
+                (stencil-coordinates fret-coordinate string-coordinate))
+              (extent (cons (- scale-dot-radius) scale-dot-radius))
+              (finger (caddr mypair))
+              (finger (if (number? finger) (number->string finger) finger))
+              (dot-stencil (if (eq? dot-color 'white)
+                             (ly:stencil-add
+                               (make-circle-stencil
+                                 scale-dot-radius scale-dot-thick #t)
+                               (ly:stencil-in-color
+                                 (make-circle-stencil
+                                   (- scale-dot-radius (* 0.5 scale-dot-thick))
+                                   0  #t)
+                                 1 1 1))
+                             (make-circle-stencil
+                               scale-dot-radius scale-dot-thick #t)))
+              (positioned-dot
+                (ly:stencil-translate dot-stencil dot-coordinates))
+              (labeled-dot-stencil
+                (cond
+                  ((or (eq? finger '())(eq? finger-code 'none))
+                   positioned-dot)
+                  ((eq? finger-code 'in-dot)
+                   (let ((finger-label
+                           (centered-stencil
+                             (sans-serif-stencil
+                               layout props dot-label-font-mag finger))))
+                     (ly:stencil-translate
+                       (ly:stencil-add
+                         dot-stencil
+                         (if (eq? dot-color 'white)
+                           finger-label
+                           (ly:stencil-in-color finger-label 1 1 1)))
+                       dot-coordinates)))
+                  ((eq? finger-code 'below-string)
+                   (let* ((label-stencil
+                            (centered-stencil
+                              (sans-serif-stencil
+                                layout props string-label-font-mag
+                                finger)))
+                          (label-fret-offset
+                            (stencil-fretboard-offset
+                              label-stencil 'fret orientation))
+                          (label-fret-coordinate
+                            (+ (* size
+                                  (+ 1 my-fret-count finger-label-padding))
+                               label-fret-offset))
+                          (label-string-coordinate string-coordinate)
+                          (label-translation
+                            (stencil-coordinates
+                              label-fret-coordinate
+                              label-string-coordinate)))
+                     (ly:stencil-add
+                       positioned-dot
+                       (ly:stencil-translate
+                         label-stencil
+                         label-translation))))
+                  (else ;unknown finger-code
+                    positioned-dot))))
+         (if (null? restlist)
+           labeled-dot-stencil
+           (ly:stencil-add
+             (draw-dots restlist)
+             labeled-dot-stencil))))
+
+     (define (draw-thick-zero-fret)
+       "Draw a thick zeroth fret for a fret diagram whose base fret is 1."
+       (let* ((half-lowest-string-thickness
+                (* 0.5 th (string-thickness string-count thickness-factor)))
+              (half-thick (* 0.5 sth))
+              (top-fret-thick
+                (* sth (assoc-get 'top-fret-thickness details 3.0)))
+              (start-string-coordinate (- half-lowest-string-thickness))
+              (end-string-coordinate (+ (* size (1- string-count)) half-thick))
+              (start-fret-coordinate half-thick)
+              (end-fret-coordinate (- half-thick top-fret-thick))
+              (lower-left
+                (stencil-coordinates
+                  start-fret-coordinate start-string-coordinate))
+              (upper-right
+                (stencil-coordinates
+                  end-fret-coordinate end-string-coordinate)))
+         (ly:round-filled-box
+           (cons (car lower-left) (car upper-right))
+           (cons (cdr lower-left) (cdr upper-right))
+           sth)))
+
+     (define (draw-xo xo-list)
+       "Put open and mute string indications on diagram, as contained in
+@var{xo-list}."
+       (let* ((xo-font-mag
+                (* size (assoc-get
+                          'xo-font-magnification details
+                          (cond ((or (eq? orientation 'landscape)
+                                     (eq? orientation 'opposing-landscape))
+                                 0.4)
+                                (else 0.4)))))
+              (mypair (car xo-list))
+              (restlist (cdr xo-list))
+              (glyph-string (if (eq? (car mypair) 'mute)
+                              (assoc-get 'mute-string details "X")
+                              (assoc-get 'open-string details "O")))
+              (glyph-string-coordinate (* (- string-count (cadr mypair)) size))
+              (glyph-stencil
+                (centered-stencil
+                  (sans-serif-stencil
+                    layout props (* size xo-font-mag) glyph-string)))
+              (glyph-stencil-coordinates
+                (stencil-coordinates 0 glyph-string-coordinate))
+              (positioned-glyph
+                (ly:stencil-translate
+                  glyph-stencil
+                  glyph-stencil-coordinates)))
+         (if (null? restlist)
+           positioned-glyph
+           (ly:stencil-add
+             (draw-xo restlist)))))
+
+       (define (draw-capo fret)
+         "Draw a capo indicator across the full width of the fret-board
+at @var{fret}."
+         (let* ((capo-thick
+                  (* size (assoc-get 'capo-thickness details 0.5)))
+                (half-thick (* capo-thick 0.5))
+                (last-string-position 0)
+                (first-string-position (* size (- string-count 1)))
+                (fret-position ( * size (1- (+ dot-position fret))))
+                (start-point
+                  (stencil-coordinates
+                    fret-position
+                    first-string-position))
+                (end-point
+                  (stencil-coordinates
+                    fret-position
+                    last-string-position)))
+           (make-line-stencil
+             capo-thick
+             (car start-point) (cdr start-point)
+             (car end-point) (cdr end-point))))
+
+        (define (label-fret fret-range)
+          "Label the base fret on a fret diagram"
+          (let* ((base-fret (car fret-range))
+                 (label-font-mag (assoc-get 'fret-label-font-mag details 0.5))
+                 (label-space (* 0.5 size))
+                 (label-dir (assoc-get 'label-dir details RIGHT))
+                 (label-vertical-offset
+                   (assoc-get 'fret-label-vertical-offset details 0))
+                 (number-type
+                   (assoc-get 'number-type details 'roman-lower))
+                 (label-text
+                   (cond
+                     ((equal? number-type 'roman-lower)
+                      (fancy-format #f "~(~@r~)" base-fret))
+                     ((equal? number-type 'roman-upper)
+                      (fancy-format #f "~@r" base-fret))
+                     ((equal? 'arabic number-type)
+                      (fancy-format #f "~d" base-fret))
+                     (else (fancy-format #f "~(~@r~)" base-fret))))
+                 (label-stencil
+                   (centered-stencil
+                     (sans-serif-stencil
+                       layout props (* size label-font-mag) label-text)))
+                 (label-half-width
+                   (stencil-fretboard-offset
+                     label-stencil
+                     'string
+                     orientation))
+                 (label-outside-diagram (+ label-space label-half-width)))
+            (ly:stencil-translate
+              label-stencil
+              (stencil-coordinates
+                (1+ (* size label-vertical-offset))
+                (if (eq? label-dir LEFT)
+                  (- label-outside-diagram)
+                  (+ (* size (1- string-count)) label-outside-diagram))))))
+
+
+              ; Here is the body of make-fret-diagram
+              ;
+
+    (set! fret-diagram-stencil
+      (ly:stencil-add (draw-strings) (draw-frets)))
     (if (and (not (null? barre-list))
              (not (eq? 'none barre-type)))
-        (set! fret-diagram-stencil
-              (ly:stencil-add
-               (draw-barre layout props string-count fret-range size
-                           finger-code dot-position dot-radius
-                           barre-list orientation)
-               fret-diagram-stencil)))
+      (set! fret-diagram-stencil
+        (ly:stencil-add
+          (draw-barre barre-list)
+          fret-diagram-stencil)))
     (if (not (null? dot-list))
-        (set! fret-diagram-stencil
-              (ly:stencil-add
-               fret-diagram-stencil
-               (draw-dots layout props string-count my-fret-count 
-                          size finger-code dot-position dot-radius
-                          th dot-list orientation))))
+      (set! fret-diagram-stencil
+        (ly:stencil-add
+          fret-diagram-stencil
+          (draw-dots dot-list))))
     (if (= (car fret-range) 1)
-        (set! fret-diagram-stencil
-                  (ly:stencil-add
-                     fret-diagram-stencil 
-                     (draw-thick-zero-fret
-                       details string-count th 
-                       thickness-factor size orientation))))
-    (if (not (null? xo-list))
-     (let* ((diagram-fret-top 
-              (car (stencil-fretboard-extent
-                     fret-diagram-stencil
-                     'fret
-                     orientation)))
-            (xo-stencil 
-              (draw-xo layout props string-count fret-range
-                       size xo-list orientation))
-            (xo-fret-offset
-              (stencil-fretboard-offset
-                xo-stencil 'fret orientation)))
       (set! fret-diagram-stencil
         (ly:stencil-add
           fret-diagram-stencil
-          (ly:stencil-translate
-            xo-stencil
-            (stencil-coordinates
-             (- diagram-fret-top
-                xo-fret-offset
-                (* size xo-padding))
-             0 ; no string offset
-             orientation))))))
-               
-    (if (> capo-fret 0)
+          (draw-thick-zero-fret))))
+    (if (not (null? xo-list))
+      (let* ((diagram-fret-top
+               (car (stencil-fretboard-extent
+                      fret-diagram-stencil
+                      'fret
+                      orientation)))
+             (xo-stencil (draw-xo xo-list))
+             (xo-fret-offset
+               (stencil-fretboard-offset
+                 xo-stencil 'fret orientation)))
         (set! fret-diagram-stencil
-              (ly:stencil-add
-                fret-diagram-stencil
-                (draw-capo details string-count capo-fret my-fret-count
-                           th size dot-position orientation))))
+          (ly:stencil-add
+            fret-diagram-stencil
+            (ly:stencil-translate
+              xo-stencil
+              (stencil-coordinates
+                (- diagram-fret-top
+                   xo-fret-offset
+                   (* size xo-padding))
+                0)))))) ; no string offset
+
+    (if (> capo-fret 0)
+      (set! fret-diagram-stencil
+        (ly:stencil-add
+          fret-diagram-stencil
+          (draw-capo capo-fret))))
     (if (> (car fret-range) 1)
       (set! fret-diagram-stencil
         (ly:stencil-add
-           fret-diagram-stencil
-           (label-fret 
-             layout props string-count fret-range size orientation))))
-      (ly:stencil-aligned-to fret-diagram-stencil X alignment)))
+          fret-diagram-stencil
+          (label-fret fret-range))))
+    (ly:stencil-aligned-to fret-diagram-stencil X alignment)))
 
 (define (fret-parse-definition-string props definition-string)
  "Parse a fret diagram string and return a pair containing:
@@ -858,9 +825,9 @@ a fret-indication list with the appropriate values"
          (prepend-alist-chain 'fret-diagram-details details props))
    `(,props . ,output-list))) ;ugh -- hard-coded spell -- procedure better
 
-(define-public 
+(define-public
   (fret-parse-terse-definition-string props definition-string)
-  "Parse a fret diagram string that uses terse syntax; 
+  "Parse a fret diagram string that uses terse syntax;
 return a pair containing:
 @var{props}, modified to include the string-count determined by the
 definition-string, and
@@ -933,7 +900,7 @@ a fret-indication list with the appropriate values"
     `(,props . ,output-list))) ; ugh -- hard coded; proc is better
 
 
-(define-builtin-markup-command 
+(define-builtin-markup-command
   (fret-diagram-verbose layout props marking-list)
   (pair?) ; argument type (list, but use pair? for speed)
   instrument-specific-markup ; markup type
-- 
2.39.2