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Re: Sending image from separate thread back to AppController
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Re: Sending image from separate thread back to AppController

On 2004-07-20, at 22.44, Andrew Duncan wrote:

> My AppController creates a new thread (call it Thread2), which runs
> and, in its own good time, creates an NSImage. Now I want to tell the
> main (UI) thread to display this image. Of course, Thread2 knows
> nothing about the outlets to the NSImageView, so it has to ask the
> AppController to deal with this.
>
> What's the Best Practice for this one? First impulse is to give the
> new thread a pointer back to the AppController. Then Thread2 can call
> a method on the AppController, sending the image (pointer) and having
> the AppController call setNeedsDisplay on the imageView.

That would probably create problems if not everything you touch is
thread safe - including your accesses to the Cocoa libraries.

> But maybe there's some cool notification scheme or value observer or
> something in Panther that I don't know about. I'm sure this is an FAQ
> and would appreciate hearing the frequent answer.

If you can live with only supporting Panther and later, check out this
method from NSObject:

performSelectorOnMainThread:withObject:waitUntilDone:

If you need to support versions of Mac OS X earlier than Panther, you
can use ports - like Mario suggested.

j o a r

[demime 0.98b removed an attachment of type application/pkcs7-signature which had a name of smime.p7s]
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References: 
 >Sending image from separate thread back to AppController (From: Andrew Duncan <email@hidden>)



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