[racket] Using big-bang with picts

Oh, yes: that's effectively a bitmap -> image coercion. That's probably a
better thing to put than what I did in my diff.

Robby


On Mon, Feb 17, 2014 at 1:41 PM, Spencer Florence <florence at ccs.neu.edu>wrote:

> I've run into this before. The way we solved it was to rotate bitmaps my 0
> degrees: Its silly, but it works.
>
> So
>
> (define (world->image p)
>   (rotate (pict->bitmap p))
>
>
> On Mon, Feb 17, 2014 at 2:38 PM, Robby Findler <
> robby at eecs.northwestern.edu> wrote:
>
>> This does look like a bug in 2htdp/universe, tho.
>>
>> Looking at the universe code, it is not dealing with the case that it
>> gets a bitmap% object. 2htdp/image's image? predicate accepts those.
>> Probably a diff something along these lines is the right fix (warning,
>> untested!)
>>
>> ☕  git diff .
>> diff --git a/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt
>> b/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt
>> index 103ca45..98d46ff 100644
>> --- a/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt
>> +++ b/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt
>> @@ -232,7 +232,10 @@
>>        ;; Image -> Void
>>        ;; show the image in the visible world
>>        (define/public (show pict0)
>> -        (define pict (add-game-pad pict0))
>> +        (define pict1 (if (is-a? pict0 bitmap%)
>> +                          (make-object bitmap-snip% pict0)
>> +                          pict0))
>> +        (define pict (add-game-pad pict1))
>>          (send visible begin-edit-sequence)
>>          (send visible lock #f)
>>          (let ([s (send visible find-first-snip)]
>>
>>
>>
>> On Mon, Feb 17, 2014 at 12:40 PM, Jens Axel Søgaard <
>> jensaxel at soegaard.net> wrote:
>>
>>> Hi All,
>>>
>>> Is there a way to use big-bang with picts?
>>> In other words, how can I convert a pict into something that big-bang
>>> will display?
>>>
>>> The attempt below fails with this error:
>>>
>>>     collects/racket/private/class-internal.rkt:4387:0: send: no such
>>> method
>>>     method name: copy
>>>     class name: bitmap%
>>>
>>> #lang racket
>>> (require pict (only-in 2htdp/universe big-bang on-tick to-draw))
>>>
>>> (define (world->image w)
>>>   (pict->bitmap (circle w)))
>>>
>>> (big-bang 100
>>>           [on-tick add1]
>>>           [to-draw world->image])
>>>
>>>
>>> --
>>> Jens Axel Søgaard
>>>
>>> ____________________
>>>   Racket Users list:
>>>   http://lists.racket-lang.org/users
>>>
>>
>>
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>>
>
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