macOS: Fix crash in QCocoaBackingStore::format() after closing window

Closing a window results in sending an expose event to obscure the window,
which gets delivered after the corresponding QPlatformWindow has been
destroyed.

If the client application (wrongly) tries to render as a result of this
expose event, using the existing QBackingStore, it will potentially
result in a resize of the backing store, for example if the global
device pixel ratio is different from what the window had when it
still had a QPlatformWindow.

The resize in turn requires the format() of the window, but since we
no longer have a QPlatformWindow we can't base the format on that.

Change-Id: Ied6a3a745f20087c2287ad86e1c66808467b6183
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

0 files changed, 0 insertions, 0 deletions