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NSPDFImageRep vs. NSProgressIndicator

Hi, I'm a newbie to Cocoa.

I've got a multipage pdf that I'm displaying in window using an NSImageView (using an NSPDFImageRep instance). When I load the pdf, there a delay before the pdf is displayed that is long enough to make you think something's amiss, but not long enough for the busy cursor to come up. A suboptimal user experience I'd like to avoid.

So I thought I'd put a NSProgressIndicator in the window to which I'd send a startAnimating message just before displaying the pdf and a stopAnimating message afterwards. But it seems that there is something within the pdf rendering machinery that stops progress indicators cold. To prove this to myself, I wrote a small test app that starts the progress indicator spinning in a controller object's awakeFromNib method. Then I load the pdf.

To wit:

- (void)awakeFromNib
{
[_spinner setUsesThreadedAnimation:YES];
[_spinner startAnimation:self];
}

- (IBAction)loadPDF:(id)sender
{
// attempt to load a new pdf
NSImage* pdfImage = [[NSImage alloc] initByReferencingFile:@"some.pdf"];
if (pdfImage && [pdfImage isValid])
{
[pdfImage retain];
[_imageView setImage: pdfImage];
[_imageView display]; // <- spinner stops spinning here
}
}

The progress indicator grinds to a halt for the duration of the [_imageView display] call. Seems wrong to me.

The thing is, no matter what I do, the NSProgressIndicator stops animating while the pdf is being imaged.

As you can see from my awakefromNib method, I have tried the [_spinner setUsesThreadedAnimation:YES] trick, and it doesn't work.

I had a feeling that this could be due to the NSView locking focus for the duration of the display method. So I tried putting a second progress indicator in a second window by itself. Same thing, ergo, I don't think its a locked focus thing (I could be talked out of it though).

Any explanations or tips on how to get around this?

cheers,

_murat
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