Selective Mouse Button Auto-Capture

1#include <SDL.h>
2#include <bitset>
3#include <iostream>
4
5class SelectiveMouseCapture {
6public:
7  SelectiveMouseCapture() {
8    // Disable SDL's built-in auto-capture
9    SDL_SetHint(
10      SDL_HINT_MOUSE_AUTO_CAPTURE, "0"); 
11  }
12
13  void
14    EnableAutoCaptureForButton(Uint8 button) {
15    if (button < MaxButtons) {
16      autoCaptureButtons.set(button);
17    }
18  }
19
20  void
21    DisableAutoCaptureForButton(Uint8 button) {
22    if (button < MaxButtons) {
23      autoCaptureButtons.reset(button);
24    }
25  }
26
27  void HandleMouseDown(
28    SDL_MouseButtonEvent& event) {
29    if (event.button < MaxButtons &&
30      autoCaptureButtons.test(event.button)) {
31      SDL_CaptureMouse(SDL_TRUE);
32      isCapturing = true;
33    }
34  }
35
36  void HandleMouseUp(
37    SDL_MouseButtonEvent& event) {
38    if (isCapturing && event.button < MaxButtons
39      &&
40      autoCaptureButtons.test(event.button)) {
41      SDL_CaptureMouse(SDL_FALSE);
42      isCapturing = false;
43    }
44  }
45
46private:
47  static const size_t MaxButtons = 32;
48  std::bitset<MaxButtons> autoCaptureButtons;
49  bool isCapturing = false;
50};
51
52int main(int argc, char** argv) {
53  SDL_Init(SDL_INIT_VIDEO);
54  SDL_Window* window =
55    SDL_CreateWindow("Selective Capture",
56                     SDL_WINDOWPOS_CENTERED,
57                     SDL_WINDOWPOS_CENTERED,
58                     800, 600,
59                     SDL_WINDOW_SHOWN);
60
61  SelectiveMouseCapture captureManager;
62
63  // Enable auto-capture for left button only
64  captureManager.EnableAutoCaptureForButton(
65    SDL_BUTTON_LEFT); 
66
67  bool running = true;
68  while (running) {
69    SDL_Event event;
70    while (SDL_PollEvent(&event)) {
71      if (event.type == SDL_QUIT) {
72        running = false;
73      } else if (event.type ==
74        SDL_MOUSEBUTTONDOWN) {
75        captureManager.HandleMouseDown(
76          event.button);
77        std::cout << "Button "
78          << (int)event.button.button
79          << " pressed\n";
80      } else if (event.type == SDL_MOUSEBUTTONUP) {
81        captureManager.HandleMouseUp(
82          event.button);
83        std::cout << "Button "
84          << (int)event.button.button
85          << " released\n";
86      }
87    }
88
89    // Show capture state
90    bool isCaptured = SDL_GetWindowFlags(window)
91      & SDL_WINDOW_MOUSE_CAPTURE;
92    std::cout << "Capture State: " << (
93        isCaptured ? "Active" : "Inactive")
94      << "\r" << std::flush;
95  }
96
97  SDL_DestroyWindow(window);
98  SDL_Quit();
99  return 0;
100}