How can I handle multiple types of events in SDL2, such as keyboard and mouse events?

Question

Ryan McCombe · Accepted Answer

SDL2 provides an event system that allows you to handle various types of events, including keyboard and mouse events. Here's an example of how to handle multiple event types in an SDL2 application:

1#include <SDL.h>
2
3#include <iostream>
4
5int main(int argc, char* argv[]) {
6  SDL_Init(SDL_INIT_VIDEO);
7
8  SDL_Window* window{SDL_CreateWindow(
9    "Event Handling",
10    SDL_WINDOWPOS_UNDEFINED,
11    SDL_WINDOWPOS_UNDEFINED,
12    800, 600, SDL_WINDOW_SHOWN
13  )};
14
15  SDL_Event event;
16  bool quit = false;
17  while (!quit) {
18    while (SDL_PollEvent(&event)) {
19      switch (event.type) {
20        case SDL_QUIT:
21          quit = true;
22          break;
23        case SDL_KEYDOWN:
24          if (event.key.keysym.sym
25            == SDLK_ESCAPE) {
26            quit = true;
27          } else {
28            std::cout << "Key pressed: "
29              << SDL_GetKeyName(
30                event.key.keysym.sym) << '\n';
31          }
32          break;
33        case SDL_MOUSEBUTTONDOWN:
34          std::cout << "Mouse button pressed: "
35            << event.button.button << "\n";
36          break;
37        case SDL_MOUSEMOTION:
38          std::cout << "Mouse position: ("
39            << event.motion.x << ", "
40            << event.motion.y << ")\n";
41          break;
42      }
43    }
44  }
45
46  SDL_DestroyWindow(window);
47  SDL_Quit();
48
49  return 0;
50}

In this example, we use a switch statement inside the event loop to handle different event types. The event.type field determines the type of event that occurred.

For the SDL_QUIT event, we set the quit flag to true to exit the application.
For the SDL_KEYDOWN event, we check if the pressed key is the Escape key ( SDLK_ESCAPE) to quit the application. Otherwise, we print the name of the pressed key using SDL_GetKeyName.
For the SDL_MOUSEBUTTONDOWN event, we print the mouse button that was pressed using event.button.button.
For the SDL_MOUSEMOTION event, we print the current mouse position using event.motion.x and event.motion.y.

You can extend this event handling code to include additional event types and perform specific actions based on your application's requirements.

Remember to include the necessary headers and initialize SDL2 properly before handling events. Also, make sure to clean up resources, such as windows and renderers, before quitting the application.

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