sdl_fullscreentest.c

// can be built with:
// $ gcc -o sdl2test `sdl2-config --cflags` sdl_fullscreentest.c `sdl2-config --libs`
// will try to create a fullscreen window with 1920x1080 by default,
// but accepts commandline arguments to use a different resolution, like
// $ ./sdl2test 2560 1440
// will create testlog.txt and write some info there

#include <SDL.h>
#include <unistd.h>

int main(int argc, char** argv)
{
	//FILE* out = fopen("testlog.txt", "wt");
	FILE* out = stdout;
	
	SDL_Init(SDL_INIT_VIDEO);

	int winWidth = 1920;
	int winHeight = 1080;

	if(argc >= 3)
	{
		winWidth = atoi(argv[1]);
		winHeight = atoi(argv[2]);
	}

	int winFlags = SDL_WINDOW_FULLSCREEN;
	SDL_version ver;
	SDL_GetVersion(&ver);
	fprintf(out, "SDL version %d.%d.%d revision %s\n",
	        (int)ver.major, (int)ver.minor, (int)ver.patch, SDL_GetRevision());

	fprintf(out, "Creating a Window with resolution %d x %d\n", winWidth, winHeight);

	SDL_Window* win = SDL_CreateWindow("Test Fullscreen", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
	                                   winWidth, winHeight, winFlags);

	if(win != NULL)
	{
		int winW, winH;
		SDL_GetWindowSize(win, &winW, &winH);
		fprintf(out, "Creating Window successful, apparently (not NULL), size: %d %d\n", winW, winH);
		
		if(winW != winWidth || winH != winHeight)
		{
			fprintf(out, "wrong size, we got: %d %d\n", winW, winH);
			SDL_DisplayMode realMode = {};
			realMode.w = winWidth;
			realMode.h = winHeight;
			fprintf(out, "trying to really switch to %d x %d now\n", winWidth, winHeight);
			if(SDL_SetWindowDisplayMode(win, &realMode) == 0)
			{
				fprintf(out, "swiching succeeded, according to SDL\n");
			}
			else
				fprintf(out, "swiching FAILED, according to SDL\n");
			
			//sleep(1);
			
			SDL_GetWindowSize(win, &winW, &winH);
			fprintf(out, "after switching we have size: %d %d\n", winW, winH);
			SDL_SetWindowSize(win, winWidth, winHeight);
			fprintf(out, "after setwindowsize we have size: %d %d\n", winW, winH);
		}
		
		int winIdx = SDL_GetWindowDisplayIndex(win);
		if(winIdx >= 0)
		{
			SDL_DisplayMode mode;
			if(SDL_GetCurrentDisplayMode(winIdx, &mode) == 0)
			{
				fprintf(out, "we're on display %d with mode %d x %d\n", winIdx, mode.w, mode.h);
			}
			else
				fprintf(out, "Failed to get SDL Display mode: %s\n", SDL_GetError());
			
			/*int numDisplayModes = SDL_GetNumDisplayModes(winIdx);
			fprintf(out, "This display supports %d modes:\n", numDisplayModes);
			for(int i=0; i<numDisplayModes; ++i)
			{
				if (SDL_GetDisplayMode(winIdx, i, &mode) == 0)
					fprintf(out, "  %d: %d x %d @ %d Hz\n", i, mode.w, mode.h, mode.refresh_rate);
			}*/
		}
		else
			fprintf(out, "Failed to get SDL Display index: %s\n", SDL_GetError());

		sleep(1);

		SDL_DestroyWindow(win);
	}
	else
		fprintf(out, "Failed to create SDL window: %s\n", SDL_GetError());

	SDL_Quit();

	fflush(out);
	fclose(out);

	return 0;
}