Question

How to receive window focus and lost focus events using SDL2 in C

Answer 1

#include <stdio.h>
#include <stdbool.h>
#include <SDL.h>

const int WIDTH = 800;
const int HEIGHT = 600;

static SDL_Window* window = NULL;
static SDL_Renderer* renderer = NULL;

bool initialize(void) {
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        fprintf(stderr, "SDL_Init Error: %s\n", SDL_GetError());
        return false;
    }

    window = SDL_CreateWindow("SDL",
        SDL_WINDOWPOS_CENTERED,
        SDL_WINDOWPOS_CENTERED,
        WIDTH, HEIGHT, SDL_WINDOW_SHOWN);
    if (!window) {
        return false;
    }

    renderer = SDL_CreateRenderer(window, -1,
        SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);

    return true;
}

void quit(void) {
    if (renderer)
        SDL_DestroyRenderer(renderer);
    if (window)
        SDL_DestroyWindow(window);
    SDL_Quit();
}

int main(int argc, char* argv[]) {
    atexit(quit);

    if (!initialize()) {
        exit(1);
    }

    bool quit = false;
    SDL_Event event;

    while (!quit) {
        while (SDL_PollEvent(&event)) {
            switch (event.type) {
                case SDL_WINDOWEVENT:
                    switch (event.window.event) {
                        case SDL_WINDOWEVENT_ENTER:
                            puts("SDL_WINDOWEVENT_ENTER");
                            break;
                        case SDL_WINDOWEVENT_LEAVE:
                            puts("SDL_WINDOWEVENT_LEAVE");
                            break;
                    }
                break;
            case SDL_QUIT:
                quit = true;
                break;
            }
        }
    }

    return 0;
}



/*
run:

SDL_WINDOWEVENT_ENTER
SDL_WINDOWEVENT_LEAVE
SDL_WINDOWEVENT_ENTER
SDL_WINDOWEVENT_LEAVE
SDL_WINDOWEVENT_ENTER
SDL_WINDOWEVENT_LEAVE

*/

 

70+ SQL courses for beginners and professionals