problem with keyboard events (KEY_UP and KEY

problem with keyboard events (KEY_UP and KEY_LEFT)

zztop2000

Member #14,757

December 2012

Hi, (sorry for my English)
I'm new in this forum and i want to ask you about a strange behaviour.

I'm using Allegro 5.0.8 under Ubuntu 11.04 with Eclipse Indigo.

I made a simple graphic object moved by pressing the arrow keys.
When the keys are released, the object stops.
All the movements works perfectly, but when i move in a particular diagonal direction (upper-left / north-west), after the KEY_UP and KEY_LEFT are released, the object change the direction form upper-left to left, without stopping.

Here the code inside a loop:

#SelectExpand
 .
 .
 .
  4while (!terminated)
 {
  6
    al_wait_for_event(event_queue, &ev);
  8
    if (ev.type == ALLEGRO_EVENT_TIMER) {
      .
      <calculate the movement here>
      .
      redraw = true;
 14
    } 
    else if (ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE) 
    {
       terminated = true;
    }
    else if (ev.type == ALLEGRO_EVENT_KEY_DOWN)
    {
 22
      switch (ev.keyboard.keycode)
      {
      case ALLEGRO_KEY_UP:
        key[0] = true;
        break;
      case ALLEGRO_KEY_DOWN:
        key[1] = true;
        break;
      case ALLEGRO_KEY_LEFT:
        key[2] = true;
        break;
      case ALLEGRO_KEY_RIGHT:
        key[3] = true;
        break;
        }
    }
    else if (ev.type == ALLEGRO_EVENT_KEY_UP)
    {
 41
      switch (ev.keyboard.keycode)
      {
      case ALLEGRO_KEY_UP:
        key[0] = false;
        break;
      case ALLEGRO_KEY_DOWN:
        key[1] = false;
        break;
      case ALLEGRO_KEY_LEFT:
        key[2] = false;
        break;
      case ALLEGRO_KEY_RIGHT:
        key[3] = false;
        break;
      }
    }
    if(redraw && al_is_event_queue_empty(event_queue)) 
    {
       redraw = false;
       .
       .
       .
    }

The KEY_UP state is correctly updated to FALSE when i release the key but the KEY_LEFT continues to have the TRUE value.

Debugging the application i saw that the "ev.keyboard.keycode" take only the first code (84 - KEY_UP), ignoring the second keycode (82 - KEY_LEFT).
(The second keycode in this case is equal to zero).

In all the other case (upper-right, lower-left, lower-right) the "ev.keyboard.keycode" works correctly taking both the keycodes and setting them to FALSE (obviously, because is a simple int, the second keycode appears after the second call to the function "al_wait_for_event()").

Has anyone encountered this problem?

torhu

Member #2,727

September 2002

You could try ex_keyboard_events and see if the same thing happens there. It's even possible that this is a limitation of your keyboard, but hopefully it's just a bug in your code.

---
Smokin' Guns - spaghetti western FPS action

zztop2000

Member #14,757

December 2012

Thanks for the reply.

I tried with an external keyboard now and it works.

So, this is a hardware problem as you suggest.