Layer hosting view not redisplaying under PPC

FROM : Nathan Vander Wilt
DATE : Wed Jul 02 23:07:27 2008

Today I took some time again to test my app on more architectures than 
just i386, and I'm encountering a strange problem on PowerPC with a 
custom view that hosts Core Animation layers. While other built-in 
views like NSButton are redrawing fine, none of my custom layer-
hosting view's drawing shows up until I either minimize/unminimize the 
window or hide/unhide the application. This happens under Rosetta as 
well.

I fear I must be doing something subtly wrong, because (e.g.) iTunes' 
CoverFlow view works fine under Rosetta and (obviously) on a PPC Mac, 
but I'm at a loss for where to even start. "Under the hood", it seems 
to be working properly:

The view draws correctly when the app is first launched. Right after 
an event that causes a layer to need redisplay is received, my -
drawLayer:inContext: code is called and encounters no errors. All 
internal mechanisms seem to be working just the same as on Intel, the 
only difference is the drawing just doesn't actually show up.  If I 
just move the window around, still nothing changes. When I hide/unhide 
the app, without doing any further actions that might affect the view, 
the drawing expected as a result of the earlier event finally shows up!

Also, if I maximize the app on Intel, the layers in the view do their 
little implicit "grow to new size" animation. When I do this on 
PowerPC, only the first frame (or at least a very early frame) of this 
implicit animation shows. This isn't even my code, as Core Animation 
normally just stretches the cached texture, only calling -
drawLayer:inContext: code for the final frame! I would suspect this is 
a bug in Core Animation, except for the fact that it's quite a show 
stopper and doesn't seem to have stopped anyone else.

Why, only when running the version compiled for PowerPC, would my 
drawing simply not get updated as often as it should? What could I be 
doing wrong? What should I check?

thanks,
-natevw