The two are only ever called together, and combining them makes it possible
to eliminate redundant symbol loading and redundant attempts to connect
to a display server.
Vivante drivers use the VK_KHR_display extension for rendering directly
to the frame buffer. This patch adds support to the video driver for
Vulkan rendering using that method.
- Add an utility function SDL_Vulkan_Display_CreateSurface that creates
a surface using this extension. The display to use (if there are
multiple) can be overridden using the environment variable
"SDL_VULKAN_DISPLAY".
- Use this function in a new compilation unit SDL_vivantevideo.c,
which implements the SDL_VIDEO_VULKAN methods of the driver structure.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
