Implement Zoom with Mouse Scroll

1#include <SDL.h>
2#include <iostream>
3
4int main(int argc, char* argv[]) {
5  SDL_Init(SDL_INIT_VIDEO);
6  SDL_Window* window = SDL_CreateWindow(
7    "Zoom Functionality Example",
8    SDL_WINDOWPOS_UNDEFINED,
9    SDL_WINDOWPOS_UNDEFINED,
10    800, 600,
11    SDL_WINDOW_SHOWN
12  );
13
14  SDL_Event event;
15  bool running = true;
16  float zoomLevel = 1.0f; 
17
18  while (running) {
19    while (SDL_PollEvent(&event)) {
20      if (event.type == SDL_MOUSEWHEEL) {
21        if (event.wheel.y > 0) {
22          zoomLevel += 0.1f; 
23        } else if (event.wheel.y < 0) {
24          zoomLevel -= 0.1f; 
25        }
26        std::cout << "Zoom level: "
27          << zoomLevel << '\n'; 
28      }
29      if (event.type == SDL_QUIT) {
30        running = false;
31      }
32    }
33  }
34
35  SDL_DestroyWindow(window);
36  SDL_Quit();
37  return 0;
38}

1#include <SDL.h>
2#include <iostream>
3
4void Render(
5  SDL_Renderer* renderer, float zoomLevel) {
6  SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
7  SDL_RenderClear(renderer);
8
9  SDL_SetRenderDrawColor(
10    renderer, 255, 255, 255, 255);
11  int width = static_cast<int>(50 * zoomLevel); 
12  int height = static_cast<int>(50 * zoomLevel); 
13  SDL_Rect rect = {375, 275, width, height};
14  SDL_RenderFillRect(renderer, &rect);
15
16  SDL_RenderPresent(renderer);
17}
18
19int main(int argc, char* argv[]) {
20  SDL_Init(SDL_INIT_VIDEO);
21  SDL_Window* window = SDL_CreateWindow(
22    "Zoom Functionality Example",
23    SDL_WINDOWPOS_UNDEFINED,
24    SDL_WINDOWPOS_UNDEFINED,
25    800, 600,
26    SDL_WINDOW_SHOWN
27  );
28  SDL_Renderer* renderer = SDL_CreateRenderer(
29    window, -1, 0);
30
31  SDL_Event event;
32  bool running = true;
33  float zoomLevel = 1.0f;
34
35  while (running) {
36    while (SDL_PollEvent(&event)) {
37      if (event.type == SDL_MOUSEWHEEL) {
38        if (event.wheel.y > 0) {
39          zoomLevel += 0.1f;
40        } else if (event.wheel.y < 0) {
41          zoomLevel -= 0.1f;
42        }
43        std::cout << "Zoom level: "
44          << zoomLevel << '\n';
45      }
46      if (event.type == SDL_QUIT) {
47        running = false;
48      }
49    }
50    Render(renderer, zoomLevel);
51  }
52
53  SDL_DestroyRenderer(renderer);
54  SDL_DestroyWindow(window);
55  SDL_Quit();
56  return 0;
57}