Creating the Main Loop with SDL2

Dynamic Event Handling with SDL_PushEvent()

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

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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:

#include <SDL.h>
#include <iostream>

int main(int argc, char** argv) {
  SDL_Init(SDL_INIT_VIDEO);
  SDL_Window* window = SDL_CreateWindow(
    "Push Event Example", 100, 100, 640, 480, 0);
  SDL_Renderer* renderer = SDL_CreateRenderer(
    window, -1, SDL_RENDERER_ACCELERATED);

  SDL_Event customEvent;
  SDL_zero(customEvent);
  customEvent.type = SDL_USEREVENT;
  customEvent.user.code = 1;  // Custom data
  SDL_PushEvent(&customEvent);

  bool running = true;
  SDL_Event event;
  while (running) {
    while (SDL_PollEvent(&event)) {
      if (event.type == SDL_QUIT) running = false;
      if (event.type == SDL_USEREVENT) {
        std::cout << "Custom event triggered "
          "with code: " << event.user.code << "\n";
      }
    }

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);
    SDL_RenderPresent(renderer);
  }

  SDL_DestroyRenderer(renderer);
  SDL_DestroyWindow(window);
  SDL_Quit();
  return 0;
}
Custon 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.

Answers to questions are automatically generated and may not have been reviewed.

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