Display Mode Safety Timer

1#include <SDL.h>
2#include <iostream>
3
4class DisplayModeGuard {
5  SDL_Window* Window;
6  SDL_DisplayMode PreviousMode;
7  Uint32 StartTime;
8  Uint32 TimeoutMs;
9  bool Confirmed{false};
10
11public:
12  DisplayModeGuard(
13    SDL_Window* Window,
14    Uint32 TimeoutMs
15  ) : Window{Window}, TimeoutMs{TimeoutMs} {
16    // Store current mode before changes
17    SDL_GetWindowDisplayMode(
18      Window, &PreviousMode);
19    StartTime = SDL_GetTicks();
20  }
21
22  void Confirm() { Confirmed = true; }
23
24  bool HasExpired() const {
25    return !Confirmed && (SDL_GetTicks() -
26      StartTime >= TimeoutMs);
27  }
28
29  void RevertIfNeeded() {
30    if (HasExpired()) {
31      SDL_SetWindowDisplayMode(
32        Window, &PreviousMode);
33    }
34  }
35
36  ~DisplayModeGuard() { RevertIfNeeded(); }
37};
38
39int main(int argc, char* argv[]) {
40  SDL_Init(SDL_INIT_VIDEO);
41
42  SDL_Window* Window{SDL_CreateWindow(
43    "Display Mode Test",
44    SDL_WINDOWPOS_UNDEFINED,
45    SDL_WINDOWPOS_UNDEFINED,
46    800, 600, 0
47  )};
48
49  // Create guard with 15 second timeout
50  DisplayModeGuard Guard{Window, 15000};
51
52  // Try new display mode
53  SDL_DisplayMode NewMode{
54    0, 1920, 1080, 60, nullptr};
55  SDL_SetWindowDisplayMode(Window, &NewMode);
56  SDL_SetWindowFullscreen(
57    Window, SDL_WINDOW_FULLSCREEN);
58
59  std::cout << "Press Enter to confirm new display"
60    " mode or wait 15 seconds to revert\n";
61
62  // Simple event loop
63  bool Running{true};
64  while (Running) {
65    SDL_Event Event;
66    while (SDL_PollEvent(&Event)) {
67      if (Event.type == SDL_KEYDOWN &&
68        Event.key.keysym.sym == SDLK_RETURN) {
69        Guard.Confirm();
70        Running = false;
71      } else if (Event.type == SDL_QUIT) {
72        Running = false;
73      }
74    }
75
76    if (Guard.HasExpired()) { Running = false; }
77
78    SDL_Delay(16);
79  }
80
81  SDL_DestroyWindow(Window);
82  SDL_Quit();
83  return 0;
84}