[AD] Key repeats and handling screen re-opens

[Colin Ward <lists@xxxxxxxxxx>]

Hi all.

I just fixed a bug in the Amiga port of Allegro where certain games that had
an option to switch dynamically between full screen and windowed mode at
runtime were getting themselves into a loop.  It turned out to be a
keyboard handling problem.  Basically the following code (in certain games)
was to blame:

void handle_keypresses()
{
   if (key[...]{
   {
      // Change screen mode
   }
}

So let's say that handle_keypresses() is called from the game's main menu
loop (which is a busy loop). This is not nice but it's how most games seem
to work.  :-(

What happens is that in my keyboard driver, I get a signal that a key has
been pressed and set key[...] to 1.  The signal is associated with an open
screeen or window.  So now key[...] = 1 and this triggers the code above,
which changes the screen mode.  The change of screen mode usually consists
of shutting the current screen and re-opening it as a window, or vice
versa.  Now because Amiga input handling (and that of most operating
systems) is handled by receiving events from a particular screen or window
source in the OS, if the user releases the key during the screen or window
change, the key up event is never received, key[...] remains 1 and when
handle_keypresses() is called again it thinks the key is still pressed and
closes and re-opens the screen or window again!

I had to put a hack in the Amiga's screen/window handling code so that when
a screen or window was closed, it set all keys to 0.  ie.

for (index = KEY_A; index < __allegro_KEY_MAX; ++index)
{
   key[index] = 0;
}

The questions are:

1) Is the code above the correct way of resetting all keys?
2) Is there a better way of handling this situation?

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