Purpose of SDL Window Events

Why do we monitor SDL window events rather than continuously checking window properties?

Monitoring SDL window events is more efficient and practical than continuously polling for window properties. Here's why:

Efficiency

Polling involves repeatedly checking the state of properties like size, position, or flags in every frame of the game loop. This wastes CPU cycles and can degrade performance, especially in high-performance applications where every frame counts.

SDL window events are only generated when a relevant change happens, such as the window being resized or moved. This event-driven approach ensures your program reacts only when necessary.

Simplified Logic

By relying on events, you avoid cluttering your game loop with unnecessary checks. This makes your code cleaner and easier to maintain. Instead of writing logic to track every property change manually, you can handle specific events like SDL_WINDOWEVENT_RESIZED or SDL_WINDOWEVENT_MOVED when they occur.

Access to Richer Data

Window events often include additional information about the change. For instance, the SDL_WINDOWEVENT_RESIZED event provides the new dimensions of the window, saving you from having to query these properties separately.

Here's an example showing the difference. Polling might look like this:

void CheckWindowState(SDL_Window* window) {
  static int lastWidth = 0, lastHeight = 0;

  int width, height;
  SDL_GetWindowSize(window, &width, &height);

  if (width != lastWidth || height != lastHeight) {
    std::cout << "Window resized to "
      << width << "x" << height << '\n';
    lastWidth = width;
    lastHeight = height;
  }
}

A more efficient event-driven approach would look like this:

void HandleWindowEvent(SDL_WindowEvent& event) {
  if (event.event == SDL_WINDOWEVENT_RESIZED) {
    std::cout << "Window resized to "
      << event.data1 << "x" << event.data2 << '\n';
  }
}

By using events, your program is responsive, efficient, and simpler to maintain.

Window Events and Window IDs

Discover how to monitor and respond to window state changes in SDL applications

Questions & Answers

Answers are generated by AI models and may not have been reviewed. Be mindful when running any code on your device.

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Changing Window IDs
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Handling External Library Windows
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SDL_WINDOWEVENT_CLOSE vs SDL_QUIT
What's the difference between SDL_WINDOWEVENT_CLOSE and SDL_QUIT?
Handling Invalid Window IDs
What happens if I pass an invalid windowID to SDL_GetWindowFromID()?
Simulating SDL_WINDOWEVENT
How can I simulate a SDL_WINDOWEVENT for testing purposes?
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