test SDL2 input (mouse and keyboard events)

sdl2test.c

/*
 * SDL2 mousebutton test
 * 
 * build with:
 * $ gcc $(sdl2-config --cflags) -o sdl2test sdl2test.c $(sdl2-config --libs)
 */
#include <stdio.h>
#include <SDL.h>
#include <errno.h>

void eventloop(FILE* outfile) {
	while(1) {
		SDL_Event ev;
		if(SDL_PollEvent(&ev) == 0) {
			//printf(".\n");
			SDL_Delay(1);
			continue;
		}
		
		switch(ev.type) {
			case SDL_QUIT:
				fprintf(outfile, "Received SDL_QUIT - bye!\n");
				return;
				
			case SDL_MOUSEBUTTONUP:
				fprintf(outfile, "SDL_MOUSEBUTTONUP, button %d clicks %d\n", ev.button.button, (int)ev.button.clicks);
				break;
				
			case SDL_MOUSEBUTTONDOWN:
				fprintf(outfile, "SDL_MOUSEBUTTONDOWN, button %d clicks %d\n", ev.button.button, (int)ev.button.clicks);
				break;
				
			case SDL_KEYUP:
			case SDL_KEYDOWN:
				if(ev.type == SDL_KEYUP)
					fprintf(outfile, "SDL_KEYUP: ");
				else
					fprintf(outfile, "SDL_KEYDOWN: ");
				
				fprintf(outfile, "Keycode: %s (%d) Scancode: %s (%d)\n", 
					   SDL_GetKeyName(ev.key.keysym.sym), ev.key.keysym.sym,
					   SDL_GetScancodeName(ev.key.keysym.scancode),
					   ev.key.keysym.scancode);
				
				if(ev.key.keysym.sym == SDLK_q) {
					fprintf(outfile, "You pressed Q - bye!\n");
					return;
				}
				
				break;

			case SDL_MOUSEWHEEL:
				fprintf(outfile, "MouseWheel: x: %d, y: %d\n", ev.wheel.x, ev.wheel.y);
				break;
				
			case SDL_TEXTINPUT:
				fprintf(outfile, "SDL_TEXTINPUT: %s\n", ev.text.text ? ev.text.text : "<NULL>");
				break;
			
			case SDL_JOYBUTTONDOWN:
				fprintf(outfile, "SDL_JOYBUTTONDOWN dev %d button %d state %d\n",
						(int)ev.jbutton.which, (int)ev.jbutton.button, (int)ev.jbutton.state);
				break;
			case SDL_JOYBUTTONUP:
				fprintf(outfile, "SDL_JOYBUTTONUP dev %d button %d state %d\n",
						(int)ev.jbutton.which, (int)ev.jbutton.button, (int)ev.jbutton.state);
				break;
			
			case SDL_MOUSEMOTION:
			case SDL_FINGERDOWN:
			case SDL_FINGERUP:
			case SDL_FINGERMOTION:
				break; // ignore
			
			case SDL_WINDOWEVENT:
				break;
			
			default:
				// fprintf(outfile, "SDL_Event of type: 0x%x received\n", ev.type);
				break;
		}
	}
}


int main(int argc, char** argv) {
	//SDL_Init(SDL_INIT_VIDEO | SDL_INIT_JOYSTICK);
	SDL_Init(SDL_INIT_EVERYTHING);
	
	//SDL_StartTextInput();
	
	SDL_Joystick* gGameController = NULL;
	
	SDL_Window* win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
	
	//SDL_SetRelativeMouseMode(1);
	//SDL_SetWindowGrab(win, 1);
	
	SDL_SetWindowTitle(win, "SDL input test");
	
	// fill the window with black, so it shows something deterministic
	// (and works with wayland)
	{
		SDL_Surface *s = SDL_GetWindowSurface(win);
		Uint32 black = SDL_MapRGB(s->format, 0, 0, 0);
		
		SDL_FillRect(s, NULL, black);
		SDL_UpdateWindowSurface(win);
	}
	
	if( SDL_NumJoysticks() < 1 )
	{
		printf( "Warning: No joysticks connected!\n" );
	}
	else
	{
		//Load joystick
		gGameController = SDL_JoystickOpen( 0 );
		if( gGameController == NULL )
		{
			printf( "Warning: Unable to open game controller! SDL Error: %s\n", SDL_GetError() );
		}
	}
	
#ifdef _WIN32
	// output debug prints to file on windows
	const char* filename = "sdl2_test_out.txt";
#else
	// output debug prints to stdout on other OS
	const char* filename = "-";
#endif
	FILE* output = NULL;
	if(argc > 1) {
		filename = argv[1];
	}
	
	if(strcmp(filename, "-") == 0)
		output = stdout;
	else
		output = fopen(filename, "w");
	
	if(!output) {
		fprintf(stderr, "Couldn't create debug output file!\n");
		exit(1);
	}
	eventloop(output);
	
	if(strcmp(filename, "-") != 0)
		fclose(output);
	
	SDL_JoystickClose( gGameController );
	gGameController = NULL;
	
	SDL_DestroyWindow(win);

	SDL_Quit();
	
	return 0;
}

Fixed compile command (yours doesn’t work):

gcc -O2 $(sdl2-config --cflags) -o sdl2test sdl2test.c $(sdl2-config --libs)

Order matters.

Other than that, it should be noted that the window looks like it crashed, but things work well. Thanks, this helped me!

Yeah, I'm not drawing anything so the window can contain garbage.
I changed it according to your suggestion.

Danke, mira!
- caedes

Daniel Gibson dixit:

- caedes

Ach… ☻☺ Gruß //mirabilos -- <cnuke> den AGP stecker anfeilen, damit er in den slot aufm 440BX board passt… oder netzteile, an die man auch den monitor angeschlossen hat und die dann für ein elektrisch aufgeladenes gehäuse gesorgt haben […] für lacher gut auf jeder LAN party │ <nvb> damals, als der pizzateig noch auf dem monior "gegangen" ist

to get the window to display on linux wayland I needed to add a renderer.

    SDL_Window* win = SDL_CreateWindow("Hello World!", 
		SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
	
    SDL_Renderer *ren = SDL_CreateRenderer(win, -1, 0);

    SDL_SetRenderDrawColor(ren, 0, 0, 0, 255);
    SDL_RenderFillRect(ren, NULL);
    SDL_RenderPresent(ren);

to get the window to display on linux wayland I needed to add a renderer.

@ahornby: weird, that shouldn't be necessary? Though maybe I should draw something into the window.
Does it also work to add:

	{
		SDL_Surface *s = SDL_GetWindowSurface(win);
		Uint32 black = SDL_MapRGB(s->format, 0, 0, 0);
		SDL_FillRect(s, NULL, black);
		SDL_UpdateWindowSurface(win);
	}

to main(), after SDL_SetWindowTitle(win, "SDL input test"); ?

@DanielGibson yes, that also works. Must need something displayed for the window. BTW the window title the snippet is asdf

ok, updated the gist - thanks!