Handling No Displays in SDL2

When working with SDL2, it's crucial to handle cases where no displays are available, even though this is a rare scenario. Typically, the number of video displays is determined using the function SDL_GetNumVideoDisplays(). If this function returns 0, it means that SDL could not detect any available displays.

Recommended Approach

You should always check the return value of SDL_GetNumVideoDisplays() at the start of your program. If the result is 0, it's a good idea to log an error and exit gracefully or fall back to an alternative rendering solution (e.g., offscreen rendering).

Here's a simple example:

1#include <SDL2/SDL.h>
2#include <iostream>
3
4int main() {
5  if (SDL_Init(SDL_INIT_VIDEO) != 0) {
6    std::cerr << "SDL_Init failed: "
7      << SDL_GetError() << '\n';
8    return 1;
9  }
10
11  int numDisplays = SDL_GetNumVideoDisplays();
12  if (numDisplays == 0) { 
13    std::cerr << "No video displays found!\n";
14    SDL_Quit();
15    return 1; 
16  }
17
18  std::cout << "Displays found: "
19    << numDisplays << '\n';
20  SDL_Quit();
21  return 0;
22}

1// Example Output
2Displays found: 2

1// Example Error Output
2No video displays found!

When Might This Happen?

This scenario can occur in headless environments (like servers), misconfigured hardware setups, or faulty SDL initialization. Ensuring you have fallback options for these rare cases improves the robustness of your application.