Handling Input Focus for Fullscreen SDL Windows
How can I handle input focus for fullscreen SDL windows?
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 focusHandling 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_FULLSCREENflag. - Detect Focus Changes: Handle
SDL_WINDOWEVENT_FOCUS_GAINEDandSDL_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.
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.