slideshow/balloon: add `balloon-enable-3d'

collects/scribblings/slideshow/picts.scrbl

@@ -1125,6 +1125,10 @@ relative to the balloon's top-left corner.}
 
 The default background color for a balloon.
 
+@defboolparam[balloon-enable-3d on?]{
+
+A parameter that determines whether balloons are drawn with 3-D shading.}
+
 @; ----------------------------------------
 
 @subsection{Face}

collects/texpict/balloon.rkt

@@ -14,7 +14,8 @@
            balloon-pict
            balloon-point-x
            balloon-point-y
-           balloon-color)
+           balloon-color
+           balloon-enable-3d)
 
   (define-struct balloon (pict point-x point-y))
     
@@ -22,8 +23,12 @@
   (define no-brush (find-brush "white" 'transparent))
   (define black-pen (find-pen "black"))
 
+  (define balloon-enable-3d (make-parameter #t (lambda (x) (and x #t))))
+
   (define (series dc steps start-c end-c f pen? brush?)
-    (color-series dc steps #e0.5 start-c end-c f pen? brush?))
+    (if (balloon-enable-3d)
+        (color-series dc steps #e0.5 start-c end-c f pen? brush?)
+        (color-series dc 0 0 start-c end-c f pen? brush?)))
     
   (define (mk-balloon w h corner-radius spike-pos dx dy
                       [color balloon-color])
@@ -122,9 +127,10 @@
                            (if (string? color) (make-object color% color) color)
                            (lambda (i) (draw-once i #t))
                            #t #t)
-                   (send dc set-brush no-brush)
-                   (send dc set-pen (find-pen dark-color 0.5))
-                   (draw-once 0 #f)
+                   (when (balloon-enable-3d)
+                     (send dc set-brush no-brush)
+                     (send dc set-pen (find-pen dark-color 0.5))
+                     (draw-once 0 #f))
                    
                    (send dc set-pen p)
                    (send dc set-brush b)))

doc/release-notes/racket/HISTORY.txt

@@ -1,5 +1,6 @@
 Version 5.3.3.7
 Added module-compiled-cross-phase-persistent?
+slideshow/balloon: add balloon-enable-3d
 
 Version 5.3.3.6
 Added "phase-collapse" module inference and instantiation