From 2faca724e3b0670d6577c49efe8feba433055bf6 Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Wed, 18 Aug 2010 16:58:27 -0500
Subject: [PATCH] generalized the #:steps argument to play so different phases
 on an animation can take different amounts of time

---
 collects/scribblings/slideshow/play.scrbl | 14 ++++++++++++--
 collects/slideshow/play.rkt               |  7 ++++---
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/collects/scribblings/slideshow/play.scrbl b/collects/scribblings/slideshow/play.scrbl
index d997cae29a..5dd69eaf86 100644
--- a/collects/scribblings/slideshow/play.scrbl
+++ b/collects/scribblings/slideshow/play.scrbl
@@ -66,7 +66,9 @@ slide that would be registered with a timeout is instead skipped.}
 
 
 @defproc[(play-n [gen* (() (listof (real-in 0.0 1.0)) . ->* . pict?)]
-                 [#:steps steps exact-positive-integer? 10]
+                 [#:steps steps (or/c exact-positive-integer?
+                                      (improper-listof exact-positive-integer?))
+                          10]
                  [#:delay delay-secs real? 0.05]
                  [#:skip-first? skip-first? any/c #f]
                  [#:skip-last? skip-last? any/c #f]
@@ -110,7 +112,15 @@ If @racket[skip-first?] is @racket[#t], then the very first slide of
 the sequence is skipped. Similarly, if @racket[skip-last?] is
 @racket[#t], then the last slide of the sequence is skipped.
 
-The @racket[steps], @racket[delay-msecs], @racket[title],
+The @racket[steps] argument controls how many steps happen in each
+phase on the animation. If it is a number, then that number is used for
+each phase. If it is a pair of two numbers, then the first number is used
+for the first phase, and the second number is used for the rest of the
+phases. Similarly, if it is @racket[(cons num_1 (cons num_2 num_3))],
+@racket[num_1] and @racket[num_2] are used for the first two phases
+and @racket[num_3] is used for the rest.
+
+The @racket[delay-msecs], @racket[title],
 @racket[name], and @racket[layout] arguments are passed on to
 @racket[play] for each of the @math{n} segments of animation.}
 
diff --git a/collects/slideshow/play.rkt b/collects/slideshow/play.rkt
index 659ac481ed..906881cc4a 100644
--- a/collects/slideshow/play.rkt
+++ b/collects/slideshow/play.rkt
@@ -72,7 +72,8 @@
   (let ([n (procedure-arity mid)])
     (let loop ([post (vector->list (make-vector n))]
                [pre null]
-               [skip? skip-first?])
+               [skip? skip-first?]
+               [Ns N])
       (if (null? post)
           (unless skip-last?
             (slide #:title (if (procedure? title) (apply title pre) title)
@@ -89,12 +90,12 @@
                                (apply name (append pre (list n) (cdr post))))
                              name)
                   #:layout layout 
-                  #:steps N
+                  #:steps (if (pair? Ns) (car Ns) Ns)
                   #:delay secs
                   #:skip-first? skip?
                   (lambda (n)
                     (apply mid (append pre (list n) (cdr post)))))
-            (loop (cdr post) (cons 1.0 pre) #f))))))
+            (loop (cdr post) (cons 1.0 pre) #f (if (pair? Ns) (cdr Ns) Ns)))))))
 
 
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;