Can I adjust the sensitivity of mouse scroll input in SDL?

Question

Ryan McCombe · Accepted Answer

Yes, you can adjust the sensitivity of mouse scroll input in SDL. This can be done by applying a scaling factor to the scroll amount reported by SDL events.

Adjusting the sensitivity allows you to control how much a scroll wheel movement affects your application. Here's an example:

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    "Scroll Sensitivity 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 scrollPosition = 0.0f;
17  float sensitivity = 2.0f; 
18
19  while (running) {
20    while (SDL_PollEvent(&event)) {
21      if (event.type == SDL_MOUSEWHEEL) {
22        scrollPosition += (
23          event.wheel.y * sensitivity); 
24        std::cout << "Scroll position: "
25          << scrollPosition << '\n';
26      }
27      if (event.type == SDL_QUIT) {
28        running = false;
29      }
30    }
31  }
32
33  SDL_DestroyWindow(window);
34  SDL_Quit();
35  return 0;
36}

1Scroll position: 2.0
2Scroll position: 4.0

We define a sensitivity factor that multiplies the scroll amount. Higher values of sensitivity result in larger changes for the same scroll input, making the scrolling more responsive.

Within the event loop, we adjust the scroll position by multiplying the scroll amount (event.wheel.y) by the sensitivity factor. This modifies the scroll input based on the defined sensitivity.

You can allow users to customize the sensitivity factor by providing a settings menu or configuration file where they can adjust the value. This enhances the user experience by allowing personalized control over the scroll sensitivity.

Here's a more advanced example where the sensitivity factor can be adjusted dynamically:

1#include <SDL.h>
2
3#include <iostream>
4
5void HandleScrollInput(
6  SDL_MouseWheelEvent& wheel,
7  float& scrollPosition,
8  float sensitivity
9) {
10  scrollPosition += wheel.y * sensitivity;
11  std::cout << "Scroll position: "
12    << scrollPosition << '\n';  
13}
14
15int main(int argc, char* argv[]) {
16  SDL_Init(SDL_INIT_VIDEO);
17  SDL_Window* window = SDL_CreateWindow(
18    "Scroll Sensitivity Example",
19    SDL_WINDOWPOS_UNDEFINED,
20    SDL_WINDOWPOS_UNDEFINED,
21    800, 600, SDL_WINDOW_SHOWN
22  );
23
24  SDL_Event event;
25  bool running = true;
26  float scrollPosition = 0.0f;
27  float sensitivity = 2.0f;
28
29  while (running) {
30    while (SDL_PollEvent(&event)) {
31      if (event.type == SDL_MOUSEWHEEL) {
32        HandleScrollInput(
33          event.wheel, scrollPosition, sensitivity);
34      }
35      if (event.type == SDL_KEYDOWN) {
36        if (event.key.keysym.sym == SDLK_UP) {
37          sensitivity += 0.1f;  
38          std::cout << "Sensitivity increased to: "
39            << sensitivity << '\n';
40        } else if (event.key.keysym.sym == SDLK_DOWN) {
41          sensitivity -= 0.1f;  
42          std::cout << "Sensitivity decreased to: "
43            << sensitivity << '\n';
44        }
45      }
46      if (event.type == SDL_QUIT) {
47        running = false;
48      }
49    }
50  }
51
52  SDL_DestroyWindow(window);
53  SDL_Quit();
54  return 0;
55}

1Scroll position: 2.0
2Scroll position: 4.0
3Sensitivity increased to: 2.1
4Sensitivity decreased to: 2.0

By following these steps, you can adjust the sensitivity of mouse scroll input in SDL, providing a more responsive and customizable scrolling experience for users.

Handling Mouse Scrolling

Adjust Scroll Sensitivity in SDL

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