处理SDL和C ++中的关键事件

Question

I'm in the process of migrating a program from GLUT to SDL. In my current program pressing the a key results in a different response then pressing the A key. This was pretty straightforward to do in GLUT as it the keyboard function callback passed in the ASCII value of the key that was pressed.

void keyPressedFn(unsigned char key, int x, int y){
    switch(key){
    case 'a':
    // do work for a
    break;
    case 'A':
    // do work for A
    break;
    }
}

I'm struggling to replicate similar functionality in SDL as pressing the a key produces the same response regardless of if SHIFT or CAPS LOCK are pressed as well.

Is there a simple way of replicating the above function in SDL?

Edit : In the example above I only show how to handle one key, in practice however, I am going to have a list of about 15 keys that I want to respond to differently if the shift key is pressed as well.

Answer 1

Check the keyboard modifiers that are present when you get a keydown event. For example:

while(SDL_PollEvent(&event))
{
  switch(event.type)
  {
  case SDL_KEYDOWN:
    if(event.key.keysym.sym == SDLK_a)
    {
      if(event.key.keysym.mod & KMOD_SHIFT)
      {
        // Handle 'A'
      }
      else
      {
        // Handle 'a'
      }
    }
    break;

  ...

  }
}

Answer 2

SDL_keysym has mod field, which contains state of modifier keys at the time the event has been emitted. Bit-AND it with KMOD_SHIFT to check whether Shift has been active. See SDL wiki .

Answer 3

Why not just do this?

void keyPressedFn(unsigned char key, int x, int y){
    switch(key){
    case 'a':
    case 'A':
    // do work for A or a
    break;
    }
}

Do you have some other concerns that you cannot do as what I have suggested? If not I think this is as simple as it can get.