Re: [AD] Direct Input driver not intercepting Alt+Tab

["Trent Gamblin" <trent@xxxxxxxxxx>]

On Sun, August 31, 2008 11:50 am, Chris Jones said:
> Hello,
>
> I'm not sure if this is a specific Vista issue or not, but in
> Allegro 4.2 it
> doesn't seem to properly intercept the Alt+Tab key in full-screen
> games. As
> a result, when you return to the game readkey() returns a continuous
> stream
> of 0x4000 keypresses which can really mess with the game.
>
> This seems to be because GetKeyboardState doesn't return VK_MENU as
> being
> pressed, which means that the KB_ALT_FLAG doesn't get set, so then
> when Tab
> is pressed it doesn't recognise it as being alt+tab.
>
> I've got around it by making this rather dirty hack to wkeybd.c,
> which looks
> if Alt then Tab are pressed in succession and ignores the keypress,
> but this
> obviously isn't ideal and will probably cause other problems. Any
> ideas on
> this?
>
> static void key_dinput_handle_scancode(unsigned char scancode, int
> pressed)
> {
>    HWND allegro_wnd = win_get_window();
>    static int ignore_three_finger_flag = FALSE;
> +   static BOOL just_pressed_alt = FALSE;
> +
> +   if (scancode == DIK_LMENU)
> +   {
> +     just_pressed_alt = TRUE;
> +   }
> +   else if (scancode != DIK_TAB)
> +   {
> +     just_pressed_alt = FALSE;
> +   }
>
>    /* ignore special Windows keys (alt+tab, alt+space,
> (ctrl|alt)+esc) */
>    if (((scancode == DIK_TAB) && (_key_shifts & KB_ALT_FLAG))
>        || ((scancode == DIK_SPACE) && (_key_shifts & KB_ALT_FLAG))
>        || ((scancode == DIK_ESCAPE) && (_key_shifts & (KB_CTRL_FLAG
> |
> KB_ALT_FLAG)))
> +       || ((scancode == DIK_TAB) && (just_pressed_alt)))
> +   {
> +     just_pressed_alt = FALSE;
>       return;
> +   }
>
> Cheers
> Chris

Could you provide a small test program and I will take a look? The
fix will probably go into 4.3/4.4 though, as I think we've moved all
development to that branch.

Trent :{)>