Check Gamma Correction Support

1#include <SDL.h>
2
3#include <iostream>
4
5class GammaSupport {
6  SDL_Window* Window;
7  bool HasGammaSupport{false};
8  bool HasBrightnessSupport{false};
9
10public:
11  GammaSupport(SDL_Window* W) : Window{W} {
12    DetectSupport();
13  }
14
15  bool SupportsGamma() const {
16    return HasGammaSupport;
17  }
18
19  bool SupportsBrightness() const {
20    return HasBrightnessSupport;
21  }
22
23private:
24  void DetectSupport() {
25    // Test gamma ramp support
26    Uint16 TestRamp[256];
27    SDL_CalculateGammaRamp(1.0f, TestRamp);
28
29    // Try to set and then read back gamma values
30    if (SDL_SetWindowGammaRamp(
31        Window, TestRamp, TestRamp, TestRamp) >=
32      0) {
33      Uint16 ReadRamp[256];
34      if (SDL_GetWindowGammaRamp(
35          Window, ReadRamp, nullptr, nullptr) >=
36        0) {
37        // Compare original and read values
38        HasGammaSupport = true;
39        for (int i = 0; i < 256; ++i) {
40          if (TestRamp[i] != ReadRamp[i]) {
41            HasGammaSupport = false;
42            break;
43          }
44        }
45      }
46    }
47
48    // Test brightness support
49    float OriginalBrightness{
50      SDL_GetWindowBrightness(Window)};
51
52    if (OriginalBrightness > 0.0f &&
53      SDL_SetWindowBrightness(
54        Window, OriginalBrightness) >= 0) {
55      HasBrightnessSupport = true;
56    }
57
58    // Log results
59    std::cout << "Display capabilities:\n"
60      << "- Gamma Ramps: "
61      << (HasGammaSupport
62            ? "Supported"
63            : "Unsupported")
64      << "\n- Brightness: "
65      << (HasBrightnessSupport
66            ? "Supported"
67            : "Unsupported") << '\n';
68  }
69};
70
71int main() {
72  SDL_Init(SDL_INIT_VIDEO);
73
74  SDL_Window* Window{
75    SDL_CreateWindow("Gamma Support Test",
76                     SDL_WINDOWPOS_UNDEFINED,
77                     SDL_WINDOWPOS_UNDEFINED,
78                     800, 600,
79                     SDL_WINDOW_SHOWN)};
80
81  GammaSupport Support{Window};
82
83  // Use results to determine available features
84  if (Support.SupportsGamma()) {
85    std::cout << "Using gamma-based effects\n";
86  } else if (Support.SupportsBrightness()) {
87    std::cout <<
88      "Falling back to brightness control\n";
89  } else {
90    std::cout << "Using shader-based effects\n";
91  }
92
93  SDL_DestroyWindow(Window);
94  SDL_Quit();
95  return 0;
96}