[plt-scheme] empty-scene vs. nw:rectangle

Try this:

#lang scheme

(require 2htdp/universe)

(define size 4)

(define es (empty-scene size size))
(image->color-list es)

(define nw (nw:rectangle size size 'outline 'black))
(image->color-list nw)

(image=? es nw)

for size = 2, 3, 4 and look at the resulting images and lists under a  
microscope.

(It really is an accidental oversight on my side.)


On Oct 28, 2009, at 5:38 PM, Jordan Johnson wrote:

>
> Hi all,
>
> Question from one of my students: Why does
>
>  (image=? (empty-scene 200 100) (nw:rectangle 200 100 "outline"  
> "black"))
>
> evaluate to false?  (My best answer, without going digging into the  
> teachpack
> code, is that there's a non-visible difference somewhere in the  
> bitmap of the
> image.)
>
> Thanks,
> jmj
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