Re: Displaying live video -- how to notify main loop from another thread?

[icicle]

Hi!

This could help:

http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSObject_Class/Reference/Reference.html#//apple_ref/occ/instm/NSObject/performSelectorOnMainThread:withObject:waitUntilDone:

TOM

Zitat von Marek Peca <address@hidden>:

> Dear GNUsteppers,
>
> I am writing a scientific imaging application, which should display a 
> live video coming from camera with some grid and text superimposed on 
> it.
> I have achieved the basic operation using NSBitmapImageRep, filled 
> with camera images, displayed by a descendant of NSView.
>
> The GNUstep GUI (application event loop) runs in one thread, while 
> the camera input runs in another thread (there is a blocking select). 
> The problem is, how to notify the GUI, that redrawing of camera image 
> is needed. I thought, that NSView->setNeedsDisplay: YES exists for 
> this purpose, however, it does not seem to work for me. The image is 
> not updated, until some GUI events interrupt the loop (eg. mouse 
> input).
>
> How can I solve this issue? It would be fine, if I could somehow 
> propagate the request from another thread. If this is not possible, I 
> would appreciate at least, if GNUstep supports external "file" 
> events, like XtAppAddInput in XToolkit. Does it?
>
> And the second question is, whether I have chosen the right method of 
> image display: I am calling NSBitmapImageRep->draw from within 
> ImgView->drawRect:, where ImgView is descendant of NSView. Camera is 
> grabbing at few fps, 640x480x8bit, calling [imgView setNeedsDisplay: 
> YES]; if the event queue is being refreshed by continuous mouse 
> motion, I can easily get CPU load 60% on my 3GHz Pentium. (Similar 
> program under Gtk takes 2% CPU.) So I am asking, whether, and what am 
> I doing wrong.
>
> And my last question, do you know about some program or a demo under 
> GNUstep, displaying live "webcam"?
>
>
> Thank you very much for your help.
>
> Best regards,
> Marek
>
> _______________________________________________
> Gnustep-dev mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/gnustep-dev