Thanks for taking the time to respond. I am certainly not a newbie, being a Mac programmer since 1987 having brought three major applications with millions of customers to market that all run cross platform.
That aside, I am trying to understand, why Cocoa does not flush the graphics, if there has been drawn something to the window with the a method that works well otherwise. I understand coalescing updates and I want to stay away from CGContextFlush as this would cause the application to block, if another flush has to happen. We do use the invalidate/draw wherever appropriate. In this specific base, invalidate does not help, because it is not a simple redraw operation, but rather moving an object by a few pixel without tearing. The other case where we use direct drawing is the potentially hundreds of meter object that need to be updated in a very specific way at a rate that is perceived as fluent. All the best Wolfgang 2011/6/15 Graham Cox <graham....@bigpond.com> > > On 15/06/2011, at 10:30 PM, Wolfgang Kundrus wrote: > > > We have to update a lot of small onscreen objects and performance is way > better, when we travers them outside the Cocoa view tree. If we would use > invalidating, we would have to go thru our complete view tree and check for > overlaps with the update rect. > > > > Does each object have its own view? If so, then that's definitely not a > good idea. If not, then there really shouldn't be a problem - checking for > overlap with the update rect is a simple matter of a) invalidating the > update rect(s) and b) at DRAW time, call [NSView needsToDrawRect:] to test > for overlap. Invariably it is drawing that dominates performance for this > type of scenario, so a simple YES/NO test of this type is well worthwhile > and is very fast. > > If you have, say < 1000 objects that need updating, a linear list of these > will probably suffice on a modern machine. If you have more, a spatial > hashing scheme such as BSP can give useful improvements, and NSView has the > method -getRectsBeingDrawn:count: that can be used as an input to a spatial > hash. I use this technique in DrawKit, and unless the objects are especially > complex in what they draw, it's easy to achieve a refresh of many thousands > of objects within 16mS (which equates to 60fps). > > If you have found performance to be bad using Cocoa's drawing mechanism, I > suggest you must have overlooked something or made a newbie error such as 1 > view per object, because in my experience it is adequate in terms of > scheduling the updates and testing for objects needing to be drawn. Cocoa > caps the framerate at 60fps anyway so you will never do better than that, > but it sounds like you're way off base, so there's a long way to go before > giving up on the standard mechanism. > > --Graham > > > > -- Managing Director PreSonus Software Limited Bramfelder Straße 76 22305 Hamburg, Germany Phone: +49 (0) 40 - 69 70 49 32 Direct line: +49 (0) 40 - 69 70 52 45 Fax: +49 (0) 40 - 69 70 49 33 Web: www.presonussoftware.com _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
