[PATCH] wined3d: Avoid crash in swapchain_gl_present() if context could not be acquired.

[Paul Gofman]

On 11/13/19 21:16, Paul Gofman wrote:
>
> Yes, the window handle is actually valid, as well as dc. Yet
> wined3d_context_gl_set_pixel_format() called from
> wined3d_context_gl_init() fails. The failure comes from winex11.drv,
> create_gl_drawable() fails through create_client_window(), which in turn
> gets NULL get_win_data() and refuses to create the data here. This is
> some (WS_POPUP | WS_SYSMENU) window created with 1x1 size which never
> changes, and looks like it never get shown. It does not look like the
> application is serious about trying to display something with it, as
> nothing seems to be missing on the display, yet it create d3d11 device
> there (while the game is mostly d3d9), draws a few frames and gives up.
> Do you think that wined3d should try to work around any possible reason
> when display driver fails to create opengl visual or can't set pixel
> format for some other reason? If the context is not supposed to be NULL
> in swapchain present under normal circumnstances, maybe we put ERR()
> there for the time being?
>
>
>
A bit of more details on this. The swapchain for which
swapchain_gl_present() fails is not a main device swapchain. The main
device swapchain is created for the other window and is fine. That
failing swapchain is created from dxgi factory
(dxgi_factory_CreateSwapChain).

The creation of the swapchain succeeds, wined3d does not try to create a
GL context during that.

Then it gets swapchain backbuffer (dxgi d3d11_swapchain_GetBuffer) and
renders something to this backbuffer as RTV.

Then it calls d3d11_swapchain_Present() for this swapchain, and here is
when it tries to create GL context for the first time and fails in
SetPixelFormat.