Implementing an Application Loop

Dynamic Event Handling with `SDL_PushEvent()`

How can I dynamically trigger events in SDL2 using `SDL_PushEvent()`?

Abstract art representing computer programming

SDL_PushEvent() is useful for injecting custom events into the SDL event queue. Here’s how you might use it to simulate user interactions or internal signals:

1#include <SDL.h>
2#include <iostream>
3
4int main(int argc, char** argv) {
5  SDL_Init(SDL_INIT_VIDEO);
6  SDL_Window* window = SDL_CreateWindow(
7    "Push Event Example", 100, 100, 640, 480, 0);
8  SDL_Renderer* renderer = SDL_CreateRenderer(
9    window, -1, SDL_RENDERER_ACCELERATED);
10
11  SDL_Event customEvent;
12  SDL_zero(customEvent);
13  customEvent.type = SDL_USEREVENT;
14  customEvent.user.code = 1;  // Custom data
15  SDL_PushEvent(&customEvent);
16
17  bool running = true;
18  SDL_Event event;
19  while (running) {
20    while (SDL_PollEvent(&event)) {
21      if (event.type == SDL_QUIT) running = false;
22      if (event.type == SDL_USEREVENT) {
23        std::cout << "Custom event triggered "
24          "with code: " << event.user.code << "\n";
25      }
26    }
27
28    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
29    SDL_RenderClear(renderer);
30    SDL_RenderPresent(renderer);
31  }
32
33  SDL_DestroyRenderer(renderer);
34  SDL_DestroyWindow(window);
35  SDL_Quit();
36  return 0;
37}

1Custon event triggered with code: 1

This example shows how to create a custom event and push it to the event queue. When the event is processed in the event loop, it triggers a custom action, in this case, printing a message.

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