> >> On 22 Jul 2016, at 4:40 PM, Trygve Inda <cocoa...@xericdesign.com> wrote: >> >> >>> With half an eye on performance, if you *do* strictly need a copy of the >>> bitmap, note that NSBitmapImageRep conforms to NSCopying. You don’t have to >>> turn it into a TIFF and back again. >>> >>> Also, you don’t even need an NSImage - the NSImageRep can be drawn directly. >> >> >> A little deeper discussion of how my app works. > > I have an idea I know what this app is, so I understand what you need to do. I > won’t name names if you don’t :) I believe I am a registered user. > > >> >> I have a background worker thread whose purpose is to generate a continuous >> series of NSImages - from one per second to one every 5 minutes or so). I >> may have several of these worker threads working on different images. >> >> The thread starts by making a pixel buffer using: >> >> [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL ...... >> >> Then the thread goes into a loop where on each pass it draws the correct >> image into this pixel buffer. >> >> After the image is drawn it need to be handed off to the main thread to be >> drawn into a window. >> >> As soon as it is handed off, the thread starts drawing a new image, >> destroying the pixels used to create the image that was just handed off. >> >> It is likely that the image will not be received by the main thread and >> drawn into the window before the pixels in the NSBitmapImageRep are >> destroyed (because it the thread is now drawing a new image). >> >> So how is the best way to take my NSBitmapImageRep, and hand it off to the >> main thread in such a way that I can destroy the pixels immediately while >> the main thread keeps them? >> >> Would it be best to just call [myImagerep copy], and hand that to the main >> thread, and let the main thread release it once it has draw it into the >> window? >> > > > I have an idea I know what this app is, so I understand what you need to do. I > won’t name names if you don’t :) I believe I am a registered user.> I think > you have two choices.
Without naming names, I am sure your hunch is accurate. > You can pass the rep to the window using > performSelectorOnMainThread:withObject:waitUntilDone: passing YES for wait > until done, in which case your worker thread will be stalled just long enough > to draw the image and copy to the backing store. After that you’re free to > continue modifying the rep. This is how it works now, but we are running into a rare deadlock situation where the main thread asks the worker thread to end (and waits until it does so) while the worker thread is waiting for the image to be displayed. I have never seen it happen here, but I have tracked it down from hang reports and need to figure out the best way to hand the pixels off to the main thread in such a way that there are no dependencies on the original pixel buffer because as soon as the pixels are handed to the main thread, the worker thread will be changing the pixels in the original buffer. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
