X11: black screen when tabbing out of fullscreen

[ChillerDragon]

Tabbing out of fullscreen SDL2 applications used to be instant for me.

this commit introduced a black screen when tabbing in and out
8e35ff5

and this commit then changed the black screen to some sort of "fade out" window getting smaller
25cd749

Tested on X11 nvidia gnome systems on archlinux and debian 11

The not so minimal test code I used. But every fullscreen project should work.

#include <SDL2/SDL.h>

SDL_Window *g_window = NULL;

int Init(int *Screen)
{
	// print sdl version
	{
		SDL_version Compiled;
		SDL_version Linked;

		SDL_VERSION(&Compiled);
		SDL_GetVersion(&Linked);
		printf("[sdl] SDL version %d.%d.%d (compiled = %d.%d.%d)\n", Linked.major, Linked.minor, Linked.patch,
			Compiled.major, Compiled.minor, Compiled.patch);
	}
	if(!SDL_WasInit(SDL_INIT_VIDEO))
	{
		if(SDL_InitSubSystem(SDL_INIT_VIDEO) < 0)
		{
			printf("[gfx] unable to init SDL video: %s\n", SDL_GetError());
			return 1;
		}
	}
	// store desktop resolution for settings reset button
	SDL_DisplayMode DisplayMode;
	if(SDL_GetDesktopDisplayMode(*Screen, &DisplayMode))
	{
		printf("[gfx] unable to get desktop resolution: %s\n", SDL_GetError());
		return 1;
	}
	int SdlFlags = SDL_WINDOW_OPENGL | \
		       SDL_WINDOW_INPUT_GRABBED | \
		       SDL_WINDOW_INPUT_FOCUS | \
		       SDL_WINDOW_MOUSE_FOCUS | \
		       SDL_WINDOW_FULLSCREEN;
	g_window = SDL_CreateWindow(
		"SDL2",
		SDL_WINDOWPOS_CENTERED,
		SDL_WINDOWPOS_CENTERED,
		DisplayMode.w,
		DisplayMode.h,
		SdlFlags);
	return 0;
}

int main(int argc, char* argv[]) {
	if(SDL_Init(0))
	{
		puts("SDL_Init failed");
		return 1;
	}
	int Screen = 0;
	Init(&Screen);
	
	if(g_window == NULL)
	{
		puts("SDL_CreateWindow failed");
		return 1;
	}
	
	SDL_Renderer *renderer = NULL;
	renderer = SDL_CreateRenderer(g_window,
		                    -1,
		                    SDL_RENDERER_ACCELERATED | SDL_RENDERER_TARGETTEXTURE);
	if(renderer == NULL)
	{
		puts("SDL_CreateRenderer failed");
		return 1;
	}
	SDL_SetRenderDrawColor(renderer,
	                       0x10,
	                       0xb0,
	                       0x10,
	                       SDL_ALPHA_OPAQUE);
	
	SDL_RenderFillRect(renderer, NULL);
	SDL_RenderPresent(renderer);
	SDL_Event event;
	while (SDL_WaitEvent(&event) >= 0)
	{
		switch (event.type)
		{
			case SDL_QUIT:
				return(0);
				break;
			default: break;
		}
	}
	SDL_DestroyWindow(g_window);
	SDL_DestroyRenderer(renderer);
	SDL_Quit();
	return 0;
}

[ChillerDragon]

SDL_VIDEO_MINIMIZE_ON_FOCUS_LOSS=0 fixes it

[akortunov]

I got this issue with OpenMW (which uses SDL2) as well with 2.0.16 - there is a black screen for several seconds in fullsreen mode during game start, exit or tabbing in/out.

A mentioned workaround with SDL_VIDEO_MINIMIZE_ON_FOCUS_LOSS removes black screen during tabbing, but not during launch/exit.

I tested commit 25cd749 and it fixes the issue, but 2.0.16 is the latest release and it is already treated as stable by some Linux distros, so it would be nice to have a workaround for 2.0.16.