(Most of its complaints here are that these ints can be negative, although
they wouldn't been in sane cases. Checking sanity is what assertions do, and
it placates the analyzer appropriately.)
These scenarios can happen when a GPU is switched, its driver updated, or in
some virtual machines (such as Parallels) are suspended and then resumed. In
these cases, all GPU resources will already be lost, and it's up to the app to
recover.
For now, SDL's D3D11 renderer will handle this by freeing all GPU resources,
including all textures, and then sending a SDL_RENDER_TARGETS_RESET event.
It's currently up to an app to intercept this event, destroy all of its
textures, then recreate them from scratch.
SDL_WINDOWEVENT_FOCUS_LOST is now sent when an app's native window is hidden.
Likewise, SDL_WINDOWEVENT_FOCUS_GAINED is sent when an app's window is shown.
This mimicks behavior seen on iOS and Android.
SDL_WINDOWEVENT_MINIMIZED and SDL_WINDOWEVENT_RESTORED are now sent when the
app's native window is hidden and shown. Previously, these were sent when an
app was suspended and resumed. On Windows 8.x/RT, an app may be sent to the
background without being suspended, which previously meant that
SDL_WINDOWEVENT_MINIMIZED might never have been sent. (On Windows Phone 8,
however, this seems to be different, whereby apps sent to the background appear
to always get suspended.)
SDL_APP_WILLENTERBACKGROUND is now sent as soon as the app is told that it is
about to go to the background. SDL_APP_DIDENTERBACKGROUND is sent via a WinRT
'deferral operation', which is how WinRT gives apps a bit of extra time
(multiple seconds worth) to prepare for an app-backgrounding.
The distinction may be important as the deferral operation's code is always run
in a separate thread. For Direct3D-only apps, this means that between the
two SDL app-backgrounded events, SDL_APP_WILLENTERBACKGROUND will be the only
one run from the main thread. Given that some WinRT operations can only be done
on the main thread (operations to the CoreWindow fall into this category), this
could be important.
It is important to note that pre-deferral code may only have a very short bit of
time to execute code, less so than code run in the deferral operation (where
SDL_APP_DIDENTERBACKGROUND is sent from), which usually gets several seconds to
run.
SDL/WinRT did have support for OpenGL ES 2 via an older version of ANGLE/WinRT,
however its API changed a few months ago, and SDL/WinRT would crash when trying
to use it. It would also occasionally crash when using the older version.
This changeset should make SDL/WinRT work with the latest version, as
available via MS Open Tech's git repository of it at
https://github.com/msopentech/angle
Older versions of ANGLE/WinRT (from either https://github.com/stammen/angleproject
or https://bitbucket.org/DavidLudwig/angleproject) will need to be updated to
MS Open Tech's latest version.
It's been hardcoded out forever now, but I've now forcibly removed it with
the preprocessor so static analysis doesn't complain about it for now.
Eventually I want to rewrite or remove this code.
This is actually a false-positive, in this case, since Clang doesn't know
that SDL_SetError() only ever returns -1. Feature request to improve that,
with explanation about these specific SDL patches, is here:
http://llvm.org/bugs/show_bug.cgi?id=19208
Sam Lantinga
David Ludwig
Ryan C. Gordon
Andreas Schiffler