Implementing a Modal Dialog in SDL UI

1#include <SDL.h>
2#include <functional>
3#include <string>
4
5class ModalDialog : public Component {
6private:
7  std::string message;
8  SDL_Rect bounds;
9  bool isVisible{false};
10  std::function<void()> onConfirm;
11  std::function<void()> onCancel;
12
13public:
14  ModalDialog(const std::string& msg, int w,
15              int h)
16    : message{msg}, bounds{0, 0, w, h} {}
17
18  void Show(
19      std::function<void()> confirmCallback,
20      std::function<void()> cancelCallback) {
21    isVisible = true;
22    onConfirm = confirmCallback;
23    onCancel = cancelCallback;
24  }
25
26  void Hide() { isVisible = false; }
27
28  void HandleEvent(
29      const SDL_Event& e) override {
30    if (!isVisible)
31      return;
32
33    if (e.type == SDL_MOUSEBUTTONDOWN) {
34      int mouseX = e.button.x;
35      int mouseY = e.button.y;
36
37      if (mouseX >= bounds.x + 10 &&
38          mouseX <= bounds.x + 90 &&
39          mouseY >= bounds.y + bounds.h - 40 &&
40          mouseY <= bounds.y + bounds.h - 10) {
41        onConfirm();
42        Hide();
43      } else if (mouseX >=
44                 bounds.x + bounds.w - 90 &&
45                 mouseX <=
46                 bounds.x + bounds.w - 10 &&
47                 mouseY >=
48                 bounds.y + bounds.h - 40 &&
49                 mouseY <=
50                 bounds.y + bounds.h - 10) {
51        onCancel();
52        Hide();
53      }
54    }
55  }
56
57  void Render(SDL_Surface* surface) override {
58    if (!isVisible)
59      return;
60
61    // Center the dialog
62    bounds.x = (surface->w - bounds.w) / 2;
63    bounds.y = (surface->h - bounds.h) / 2;
64
65    // Draw dialog background
66    SDL_FillRect(surface, &bounds,
67                 SDL_MapRGB(surface->format,
68                            200, 200, 200));
69
70    // Draw message
71    // In a real implementation, you'd use
72    // SDL_ttf for text rendering
73
74    // Draw buttons
75    SDL_Rect confirmButton = {
76        bounds.x + 10, bounds.y + bounds.h - 40,
77        80, 30};
78    SDL_FillRect(
79        surface, &confirmButton,
80        SDL_MapRGB(surface->format, 0, 255, 0));
81
82    SDL_Rect cancelButton = {
83        bounds.x + bounds.w - 90,
84        bounds.y + bounds.h - 40, 80, 30};
85    SDL_FillRect(
86        surface, &cancelButton,
87        SDL_MapRGB(surface->format, 255, 0, 0));
88  }
89
90  bool IsVisible() const { return isVisible; }
91};

1#include <iostream>
2
3class UI {
4private:
5  std::vector<std::unique_ptr<Component>>
6  components;
7  ModalDialog dialog{"Are you sure?", 300, 150};
8
9public:
10  UI() {
11    components.push_back(
12        std::make_unique<Button>(
13            10, 10, 100, 50, "Show Dialog"));
14    components.push_back(
15        std::make_unique<ModalDialog>(dialog));
16  }
17
18  void HandleEvent(const SDL_Event& e) {
19    if (dialog.IsVisible()) {
20      dialog.HandleEvent(e);
21    } else {
22      for (auto& component : components) {
23        component->HandleEvent(e);
24      }
25    }
26  }
27
28  void Render(SDL_Surface* surface) {
29    for (auto& component : components) {
30      component->Render(surface);
31    }
32    dialog.Render(surface);
33  }
34
35  void ShowDialog() {
36    dialog.Show(
37        []() { std::cout << "Confirmed!\n"; },
38        []() { std::cout << "Cancelled!\n"; });
39  }
40};
41
42int main() {
43  // SDL initialization code...
44
45  UI ui;
46  SDL_Event event;
47  bool quit = false;
48
49  while (!quit) {
50    while (SDL_PollEvent(&event)) {
51      if (event.type == SDL_QUIT) {
52        quit = true;
53      } else if (event.type ==
54                 SDL_MOUSEBUTTONDOWN) {
55        if (event.button.x >= 10 &&
56            event.button.x <= 110 &&
57            event.button.y >= 10 &&
58            event.button.y <= 60) {
59          ui.ShowDialog();
60        }
61      }
62      ui.HandleEvent(event);
63    }
64
65    // Clear the screen
66    SDL_FillRect(surface, nullptr,
67                 SDL_MapRGB(surface->format,
68                            255, 255, 255));
69
70    // Render the UI
71    ui.Render(surface);
72
73    SDL_UpdateWindowSurface(window);
74  }
75
76  // SDL cleanup code...
77  return 0;
78}