Add preliminary GUI configurator.

So far you can set keys for a single layer. Emitting scheme files,
changing layers, and many other things are missing.

It uses immutable structs and immutable vectors, which Racket does not
support very well; might need to change it into a mutable, imperative program.

gui.rkt

@@ -0,0 +1,153 @@
+#lang racket/gui
+
+(require racket/match)
+
+(define (vector-set v i o) ; =(
+  (vector->immutable-vector
+   (for/vector ([j (in-range (vector-length v))])
+     (if (= i j)
+         o
+         (vector-ref v j)))))
+
+(define call-c-func void) ; for microscheme compatibility
+
+(include "keycodes.scm")
+(include "layout.scm")
+
+(define width 260)
+(define height 132)
+
+(define cols 12)
+(define rows 4)
+(define angle (degrees->radians 10))
+
+(define alps-switch-width 15.34)
+(define alps-switch-height 12.49)
+(define cherry-switch-width 13.62)
+(define cherry-switch-height 13.72)
+(define cherry? false)
+(define switch-height (if cherry? cherry-switch-height alps-switch-height))
+(define switch-width (if cherry? cherry-switch-width alps-switch-width))
+
+(define switch-spacing 19.0)
+(define bottom 95) ; outer bottom
+
+(define column-offsets `(8 5 0 6 11
+                           8
+                           8
+                           11 6 0 5 8))
+
+(define (draw-switch canvas row col)
+  (let* ([x (* (+ 1 col) switch-spacing)]
+         [y (+ (list-ref column-offsets col) (* switch-spacing (+ row 1)))])
+    (send canvas draw-rectangle x y switch-width switch-height)
+    (list x y)))
+
+(define hand-height (+ (* switch-spacing rows) (- switch-spacing switch-height)
+                       (list-ref column-offsets 0)))
+(define switch-x-offset -6.5)
+(define switch-y-offset (- bottom hand-height -3.5))
+
+(struct state (layers layer row col mode scale) #:transparent)
+
+(define (selected? st row col)
+  (and (= row (state-row st)) (= col (state-col st))))
+
+(define (selected st)
+  (+ (state-col st) (* (state-row st) cols)))
+
+(define font (make-font #:size 8 #:face "Inconsolata"))
+(define small-font (make-font #:size 4 #:face "Inconsolata"))
+
+(define ((draw state-box) _ canvas)
+  (let ((st (unbox state-box)))
+    (send canvas set-scale (state-scale st) (state-scale st))
+    (for/list ([col (in-range cols)]
+               #:when true
+               [row (if (or (= 5 col) (= 6 col)) '(2 3) (in-range rows))])
+      (send canvas set-pen (if (selected? st row col)
+                               "red" "black") 1 'solid)
+      (if (and (equal? (state-mode st) 'set) (selected? st row col))
+          (send canvas set-brush "black" 'solid)
+          (send canvas set-brush "black" 'transparent))
+      (let* ((xy (draw-switch canvas row col))
+             (key (vector-ref (vector-ref (state-layers st)
+                                          (state-layer st))
+                              (+ col (* row cols))))
+             (special? (and key (< 1 (string-length key)))))
+        (when key
+          (send canvas set-font (if special? small-font font))
+          (send canvas draw-text key
+                (+ (first xy) (if special? 2 4))
+                (+ (second xy) (if special? 2 0))))))))
+
+(define (move st dx dy)
+  (struct-copy state st
+               (row (modulo (+ dy (state-row st)) rows))
+               (col (modulo (+ dx (state-col st)) cols))))
+
+(define (handle-select st keycode)
+  (case keycode
+    [(right) (move st 1 0)]
+    [(left) (move st -1 0)]
+    [(up) (move st 0 -1)]
+    [(down) (move st 0 1)]
+    [(#\-) (struct-copy state st (scale (* (state-scale st) 0.9)))]
+    [(#\=) (struct-copy state st (scale (* (state-scale st) 1.1)))]
+    ['escape (struct-copy state st (mode 'quit))]
+    [(#\return) (struct-copy state st (mode 'set))]
+    [(#\tab) (printf "~s~n" st) st]
+    [(release) st]
+    [else (printf "~s~n" keycode) st]))
+
+(define (key-for keycode)
+  (case keycode
+    [(control) "ctrl"]
+    ;; TODO: alt and super for some reason don't show at all??
+    [(escape) "esc"]
+    [(shift) "shft"]
+    [(insert) "ins"]
+    [(next) "pgdn"]
+    [(prior) "pgup"]
+    [(#\rubout) "del"]
+    [(#\space) "spc"]
+    [(#\backspace) "bksp"]
+    [(#\return) "enter"]
+    [else (format "~a" keycode)]))
+
+(define (update-layout st keycode)
+  (vector-set (state-layers st) (state-layer st)
+              (vector-set (vector-ref (state-layers st)
+                                      (state-layer st))
+                          (selected st) (key-for keycode))))
+
+(define (handle-set st keycode)
+  (if (equal? 'release keycode)
+      st
+      (struct-copy state st
+                   (layers (update-layout st keycode))
+                   (mode 'select))))
+
+(define (handle-key canvas state-box keycode)
+  (let ((st (unbox state-box)))
+    (case (state-mode st)
+      ['select (set-box! state-box (handle-select st keycode))]
+      ['set (set-box! state-box (handle-set st keycode))])
+    (send canvas refresh)))
+
+(define (main)
+  (let ([frame (new frame% [label "Menelaus"])]
+        [state-box (box (state (vector (make-vector (* rows cols) #f))
+                               0 0 0 'select 2.5))])
+    (new (class canvas%
+           (define/override (on-char event)
+             (handle-key this state-box (send event get-key-code))
+             (when (equal? 'quit (state-mode (unbox state-box)))
+               (send frame show #f)))
+           (super-new))
+         [parent frame]
+         [paint-callback (draw state-box)])
+    (send frame show #t)))
+
+(module+ main
+  (main))