Implementing Resizable UI Components in SDL

Implementing resizable UI components in SDL requires careful management of component dimensions and positions. Here's a step-by-step approach to create resizable components:

Define a base ResizableComponent class:

1#include <SDL.h>
2
3class ResizableComponent {
4protected:
5  SDL_Rect bounds;
6
7public:
8  ResizableComponent(int x, int y, int w, int h)
9    : bounds{x, y, w, h} {}
10
11  virtual void Resize(int newWidth,
12                      int newHeight) {
13    bounds.w = newWidth;
14    bounds.h = newHeight;
15  }
16
17  virtual void Render(SDL_Surface* surface) = 0;
18};

Implement specific resizable components:

1#include "SDL_surface.h"
2
3class ResizableButton
4    : public ResizableComponent {
5public:
6  ResizableButton(int x, int y, int w, int h)
7    : ResizableComponent(x, y, w, h) {}
8
9  void Render(SDL_Surface* surface) override {
10    SDL_FillRect(surface, &bounds,
11                 SDL_MapRGB(surface->format,
12                            200, 200, 200));
13  }
14};

Handle resize events in your main loop:

1#include <iostream>
2
3int main() {
4  // SDL initialization code...
5
6  ResizableButton button{10, 10, 100, 50};
7
8  SDL_Event event;
9  bool quit = false;
10
11  while (!quit) {
12    while (SDL_PollEvent(&event)) {
13      if (event.type == SDL_QUIT) {
14        quit = true;
15      } else if (event.type ==
16                 SDL_WINDOWEVENT) {
17        if (event.window.event ==
18            SDL_WINDOWEVENT_RESIZED) {
19          int newWidth = event.window.data1;
20          int newHeight = event.window.data2;
21          button.Resize(newWidth / 2,   
22                        newHeight / 2); 
23          std::cout << "Window resized to "
24              << newWidth << "x"
25              << newHeight << "\n";
26        }
27      }
28    }
29
30    // Rendering code...
31    button.Render(surface);
32    SDL_UpdateWindowSurface(window);
33  }
34
35  // SDL cleanup code...
36  return 0;
37}

This approach allows you to create UI components that can adapt to window size changes. The ResizableComponent base class provides a common interface for resizing, which you can override in derived classes to implement specific resizing behavior.

When the window is resized, the SDL_WINDOWEVENT_RESIZED event is triggered, allowing you to update your UI components accordingly. In this example, we're resizing the button to half the new window dimensions, but you could implement more complex logic based on your specific UI layout needs.

Remember to handle edge cases, such as minimum sizes for components, to ensure your UI remains usable even with extreme window sizes. You might also want to implement a layout system that automatically adjusts component positions based on the new sizes.