Re: MCL 2.0.1 wierdness

[reti@cambridge.apple.com (Kalman Reti)]

At  9:06 AM 11/10/94 -0500, Bill St. Clair wrote:
>At 9:53 PM 11/9/94, abegel@media.mit.edu wrote:
>>I'm seeing a strange behavior in MCL.
>>
>>when I do
>>(loop for obj in list-of-objects
>>       do (with-focused-view view
>>             (set-clip-region some-other-region)
>>             (draw obj)))
>>
>>I get strange clipping problems. The clipping regions are just wrong.
>>Yet, if inside the with-focused-view, I put in a thing to save the
>>current clip-region and then restore after the (draw obj) while still in the
>>loop, it works.
>>Isn't (with-focused-view supposed to reset the view's clipping region? Even
>>if I set it differently inside?
>
>Yes.

Maybe that's what it is supposed to do, but the code currently uses view-clip-region
to get the clip region it calls #_SetClip on.  That means if you change what that
returns while inside a with-focused-view, it is permanent.

>
>>
>>What's up with this?
>
>The only thing I can think of is that your code is being called
>when view is already focused, in which case the with-focused-view
>in the loop is a nop, and any drawing that happens after the loop
>exits will still see the last value of some-other-region
>as the clip region. Try changing it to:
>
>(with-focused-view nil
>  (loop for obj in list-of-objects
>                do (with-focused-view view
>                   (set-clip-region some-other-region)
>                   (draw obj))))
>

A workaround is to use #_SetClip directly inside the loop (instead of
calling set-clip-region), e.g.

 (with-focused-view nil
   (loop for obj in list-of-objects
                 do (with-focused-view view
                    (#_SetClip :ptr some-other-region)
                    (draw obj))))


>If that doesn't work, and you can distill your code into a
>small, self contained, example that illustrates the problem,
>I'll look at it.