Managing Window Input Focus

Handling Input Focus for Fullscreen SDL Windows

How can I handle input focus for fullscreen SDL windows?

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Handling input focus for fullscreen SDL windows is similar to handling it for windowed mode, but there are a few additional considerations due to the nature of fullscreen applications.

Creating a Fullscreen Window

First, create a fullscreen window using the SDL_WINDOW_FULLSCREEN or SDL_WINDOW_FULLSCREEN_DESKTOP flag:

#include <SDL.h>

class FullscreenWindow {
public:
  FullscreenWindow() {
    SDL_Init(SDL_INIT_VIDEO);

    SDLWindow = SDL_CreateWindow(
      "Fullscreen Window",
      SDL_WINDOWPOS_CENTERED,
      SDL_WINDOWPOS_CENTERED,
      800, 600,
      SDL_WINDOW_FULLSCREEN 
    );
  }

  ~FullscreenWindow() {
    SDL_DestroyWindow(SDLWindow);
    SDL_Quit();
  }

  SDL_Window* SDLWindow{nullptr};
};

int main(int argc, char** argv) {
  FullscreenWindow GameWindow;
  SDL_Event Event;

  while (true) {
    while (SDL_PollEvent(&Event)) {
      if (Event.type == SDL_QUIT) {
        return 0;
      }
    }
  }

  return 0;
}

Detecting Focus Changes

Detecting focus changes in fullscreen mode is crucial for handling input correctly. You can use the SDL_WINDOWEVENT events to determine when the window gains or loses focus:

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

class FullscreenWindow {/*...*/}; void HandleWindowEvent(SDL_WindowEvent& E) { if (E.event == SDL_WINDOWEVENT_FOCUS_GAINED) { std::cout << "Fullscreen window gained focus\n"; } else if (E.event == SDL_WINDOWEVENT_FOCUS_LOST) { std::cout << "Fullscreen window lost focus\n"; } } int main(int argc, char** argv) { FullscreenWindow GameWindow; SDL_Event Event; while (true) { while (SDL_PollEvent(&Event)) { if (Event.type == SDL_QUIT) { return 0; } if (Event.type == SDL_WINDOWEVENT) { HandleWindowEvent(Event.window); } } } return 0; }
Fullscreen window gained focus
Fullscreen window lost focus

Handling Focus Loss

When a fullscreen window loses focus, it might minimize or be obscured by other windows. It’s important to handle these events properly to maintain a good user experience. You can automatically restore focus or pause your game when focus is lost.

void HandleWindowEvent(SDL_WindowEvent& E) {
  if (E.event == SDL_WINDOWEVENT_FOCUS_GAINED) {
    std::cout << "Fullscreen window gained focus\n";
  } else if (E.event == SDL_WINDOWEVENT_FOCUS_LOST) {
    std::cout << "Fullscreen window lost focus\n";
    // Optionally restore focus
    SDL_RaiseWindow(SDL_GetWindowFromID(E.windowID));  
  }
}

Pausing on Focus Loss

For games, it’s common to pause the game when the window loses focus. You can implement this by setting a flag in your event handling logic:

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

class FullscreenWindow {/*...*/}; bool isPaused = false; void HandleWindowEvent(SDL_WindowEvent& E) { if (E.event == SDL_WINDOWEVENT_FOCUS_GAINED) { std::cout << "Fullscreen window gained focus\n"; isPaused = false; } else if (E.event == SDL_WINDOWEVENT_FOCUS_LOST) { std::cout << "Fullscreen window lost focus\n"; isPaused = true; } } int main(int argc, char** argv) { FullscreenWindow GameWindow; SDL_Event Event; while (true) { while (SDL_PollEvent(&Event)) { if (Event.type == SDL_QUIT) { return 0; } if (Event.type == SDL_WINDOWEVENT) { HandleWindowEvent(Event.window); } } if (isPaused) { SDL_Delay(100); // Reduce CPU usage while paused continue; } // Game logic here } return 0; }

Summary

  • Create Fullscreen Window: Use SDL_WINDOW_FULLSCREEN flag.
  • Detect Focus Changes: Handle SDL_WINDOWEVENT_FOCUS_GAINED and SDL_WINDOWEVENT_FOCUS_LOST.
  • Restore Focus: Optionally restore focus using SDL_RaiseWindow().
  • Pause on Focus Loss: Implement pausing logic to improve user experience.

Handling input focus for fullscreen SDL windows ensures a smooth and responsive experience, especially for games and immersive applications.

This Question is from the Lesson:

Managing Window Input Focus

Learn how to manage and control window input focus in SDL applications, including how to create, detect, and manipulate window focus states.

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

This Question is from the Lesson:

Managing Window Input Focus

Learn how to manage and control window input focus in SDL applications, including how to create, detect, and manipulate window focus states.

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