[plt-scheme] Yet another question. And this time: animations

The error is "instantiate: unused initialization arguments: (bitmap 
#<struct:bitmap%>) for instantiated class: bitmap-dc%"
Sorry for the double mail...

I wrote:

> I actually used on-paint, not refresh, but I had to clear the canvas 
> before redrawing - otherwise it would leave a trail behind...
> What's wrong with calling on-paint from other threads though? That's 
> what I did...
> Anyway, I have a new problem with double buffering:
> (define bmp (make-object bitmap% 10000 10000 #f))
> (define bmp-dc (instantiate bitmap-dc% () (bitmap bmp)))
> --> Unused instantiation variable error (or something like that, don't 
> remember ran it from a computer at the uni this morning...)
> Why is that?
>
> Katsmall the Wise
> kela_bit at netvision.net.il
>
> Matthew Flatt wrote:
>
>> I think another problem is that `refresh' clears the canvas before it
>> calls `on-paint'. I'll will add a flag in the near future to disable
>> the clear.
>>
>> Meanwhile, you can call `on-paint' directly if you're running in the
>> handler thread.
>>
>> Matthew
>>
>> At Sun, 2 Mar 2003 16:36:59 -0600, Robert Bruce Findler wrote:
>>  
>>
>>> You can use offscreen bitmaps. Put the next frame of the animation into
>>> a bitmap and then just draw that into the canvas.
>>>
>>> Robby
>>>
>>> At Mon, 03 Mar 2003 00:08:51 +0200, Katsmall the Wise wrote:
>>>   
>>>
>>>>  For list-related administrative tasks:
>>>>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme
>>>>
>>>> Hello again,
>>>>
>>>> Now that I have normal drawings settled, what about some 
>>>> animations? Are they possible?
>>>> I tried making moving parts via boxes which are set every 0.1 secs 
>>>> and then refresh the canvas, yet (quite logically) the screen 
>>>> blinks like that...
>>>> Is there a built-in way to make animations?
>>>>
>>>> Katsmall the Wise
>>>> kela_bit at netvision.net.il
>>>>