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tightened up the check on polygon to make sure the posns contain reals

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closes PR 10997
This commit is contained in:
Robby Findler 2010-12-25 20:33:33 -06:00
parent c926656b8a
commit 7282e19178
4 changed files with 22 additions and 2 deletions
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1
collects/2htdp/image.rkt
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@ -106,6 +106,7 @@ and they all have good sample contracts. (It is amazing what we can do with kids
pen-style?
pen-cap?
pen-join?
real-valued-posn?
color-red color-blue color-green color? color
pen-color pen-width pen-style pen-cap pen-join

9
collects/2htdp/private/img-err.rkt
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@ -10,6 +10,7 @@
pen-style?
pen-cap?
pen-join?
real-valued-posn?
check-mode/color-combination)
(require htdp/error
@ -231,6 +232,10 @@
(andmap posn? arg))
'list-of-posns
i arg)
(check-arg fn-name
(andmap real-valued-posn? arg)
'list-of-posns-with-real-valued-x-and-y-coordinates
i arg)
(check-arg fn-name
(>= (length arg) 3)
'list-of-at-least-three-posns
@ -293,6 +298,10 @@
(define (pen-join? arg)
(member (if (string? arg) (string->symbol arg) arg)
'(round bevel miter)))
(define (real-valued-posn? arg)
(and (posn? arg)
(real? (posn-x arg))
(real? (posn-y arg))))
;; checks the dependent part of the 'color' specification

5
collects/2htdp/tests/test-image.rkt
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@ -1914,6 +1914,11 @@
'solid (make-pen "black" 12 "solid" "round" "round"))
=>
#rx"^polygon: expected <image-color>")
(test/exn (polygon (list (make-posn 0 0+1i) (make-posn 100 0) (make-posn 100 100))
'solid (make-pen "black" 12 "solid" "round" "round"))
=>
#rx"^polygon: expected <list-of-posns-with-real-valued-x-and-y-coordinates>")
(test/exn (save-image "tri.png" (triangle 50 "solid" "purple"))
=>

9
collects/teachpack/2htdp/scribblings/image.scrbl
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@ -559,11 +559,11 @@ the @scheme[point-count] argument determines how many points the star has.
}
@defproc*[([(polygon [vertices (listof posn?)]
@defproc*[([(polygon [vertices (listof real-valued-posn?)]
[mode mode?]
[color image-color?])
image?]
[(polygon [vertices (listof posn?)]
[(polygon [vertices (listof real-valued-posn?)]
[outline-mode (or/c 'outline "outline")]
[pen-or-color (or/c pen? image-color?)])
image?])]{
@ -1266,6 +1266,11 @@ Using @racket["pinhole"] or @racket['pinhole] is only allowed when all of the im
Determines if @racket[x] is an integer greater than or equal to @racket[1].
}
@defproc[(real-valued-posn? [x any/c]) boolean?]{
Determines if @racket[x] is a @racket[posn] whose @racket[_x] and @racket[_y]
fields are both @racket[real?] numbers.
}
@defstruct[pen ([color image-color?]
[width (and/c real? (<=/c 0 255))]
[style pen-style?]