On 12/13/18 11:05 AM, Matt Jacobson wrote:
The buffered nature of the Mac OS X window system means that windows can
“display” (i.e., go through the process of updating) even when ordered
out. Ordered-out windows /can/ occasionally be seen on screen (consider
App Exposé, which shows minimized windows, or Show All Tabs in apps
using NSWindow tabbing), and the system may snapshot or display
ordered-out windows for various reasons at other times, too.
In general, I’d say: you should not /rely/ on the fact that ordered-out
windows are displayed—in the future, the system might choose to defer it
as an optimization—but neither should you expect it not to happen.
Simply bailing out of -drawRect: (which, incidentally, is called on
/views/, not windows) seems like a bad idea, since the window may
display into an invalid state, which could result in corruption. I’d
instead investigate the underlying cause of the crash, which may result
from your view attempting to use an object that it does not hold a
strong (or weak-upgraded-to-strong) reference to.
The view was using a C++ object that had been destroyed during closing
of my document. I'm afraid that if I start playing with the order of
destruction, I'm likely to break something else. But I can be more
precise about when I decline to draw, by having my document post a
notification when it starts to shut down.
Thanks for the reply.
On Dec 13, 2018, at 10:44 AM, James Walker <jam...@frameforge3d.com
<mailto:jam...@frameforge3d.com>> wrote:
I was getting a crash on quit resulting from a drawRect: method being
called on a window that had been ordered out. I can solve the
immediate problem just by bailing out of drawRect: if the window is
invisible, but I wish I understood what's going on. The call stack
shows a run loop observer calling CA::Transaction::commit() resulting
in -[NSWindow displayIfNeeded] being called, but I don't know why
displayIfNeeded would do anything with an invisible window.
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