Why do SDL2 enumerations have high unexpected values?

Question

I came across difficulties in debugging a SDL2 program: when I printed the values of enumerations such as SDL_EventType or SDL_Keycode , the values displayed were incredibly high and different from each other. For example, the event type SDL_KEYDOWN corresponded to 768 - and there aren't 769 elements in the enumeration SDL_EventType !

I made a little test to see if this strange behaviour was due to my program, but the behaviour was still there:

#include <stdio.h>
#include "SDL.h"

int main(int argc, char *argv[])
{
  SDL_Init(SDL_INIT_VIDEO);
  SDL_Event event;
  SDL_Window *wind = SDL_CreateWindow("ee", 700, 100, 300, 300, 0);
  while (SDL_PollEvent == 1)
    SDL_PollEvent(&event);
  while (1)
  {
    SDL_PollEvent(&event);
    if (event.type == SDL_QUIT || event.key.keysym.sym == SDLK_ESCAPE)
      break;
    fprintf(stderr, "type = %d\n", event.type);
    event.type = 0;
    SDL_Delay(15);
  }
  printf("%d\n", SDL_GetTicks());
  SDL_Quit();
    return 0;
}

Printing SDLK_DOWN , SDL_MOUSEMOTION or such keywords outputs the same result than the previous program, which is coherent. But why are these values not coherent with the enumeration type?

Answer 1

If you look at SDL_events.h then you'll see something like:

/* Window events */
SDL_WINDOWEVENT    = 0x200, /**< Window state change */
SDL_SYSWMEVENT,             /**< System specific event */

/* Keyboard events */
SDL_KEYDOWN        = 0x300, /**< Key pressed */
SDL_KEYUP,                  /**< Key released */

So they are just defined with such spread values. The rationale behind this is to allow adding new values without breaking backwards compatibility while keeping certain enumerator values grouped.

Answer 2

You seem to be misusing events. In your case:

if (event.type == SDL_QUIT || event.key.keysym.sym == SDLK_ESCAPE)

However, event is basically a huge union and fields inside event.key are only valid when event.type is one of key-related events.

Maybe here lies your problem? To me that sounds like you misinterpreting what SDL_PollEvent returns.

EDIT: The person before me seems to be more on topic, however my point still stands. Admitedly, not exactly what you're asking about but you might still watch out for that.