[AD] DirectX fullscreen alt-tab

[Peter Wang <novalazy@xxxxxxxxxx>]

Hi,

In the attached program:

AFAIK I'm following the guidelines for lost devices, but after
alt-tabbing a few times it often gets into a state where the screen is
no longer drawn.  The log file shows a lot of
"D3DERR_INVALIDCALL in reset" so I guess it wasn't reset properly.

The only slightly tricky thing is that I'm using al_put_pixel
draw to an offscreen video bitmap, i.e. region locking.

Alt-tabbing seemed to work reliably though when I used al_put_pixel
to draw to the backbuffer.

Tested in XP and Vista, 5.1 branch.

Peter

#include <allegro5/allegro.h>

int main(void)
{
   const int w = 800;
   const int h = 600;
   ALLEGRO_DISPLAY *dpy;
   ALLEGRO_BITMAP *bmp;
   ALLEGRO_TIMER *timer;
   ALLEGRO_EVENT_QUEUE *queue;
   ALLEGRO_EVENT ev;
   bool redraw;
   bool lost;

   if (!al_init())
      return 1;
   al_install_keyboard();

   al_set_new_display_flags(ALLEGRO_FULLSCREEN);
   dpy = al_create_display(w, h);
   if (!dpy)
      return 1;

   al_set_new_bitmap_flags(ALLEGRO_NO_PRESERVE_TEXTURE);
   bmp = al_create_bitmap(w, h);
   if (!bmp)
      return 1;

   timer = al_create_timer(1/60.0);

   queue = al_create_event_queue();
   al_register_event_source(queue, al_get_keyboard_event_source());
   al_register_event_source(queue, al_get_timer_event_source(timer));
   al_register_event_source(queue, al_get_display_event_source(dpy));

   al_start_timer(timer);
   redraw = false;
   lost = false;

   for (;;) {
      al_wait_for_event(queue, &ev);
      if (ev.type == ALLEGRO_EVENT_KEY_CHAR && ev.keyboard.unichar == 27) {
         break;
      }
      if (ev.type == ALLEGRO_EVENT_TIMER) {
         redraw = true;
      }
      if (ev.type == ALLEGRO_EVENT_DISPLAY_LOST) {
         lost = true;
      }
      if (ev.type == ALLEGRO_EVENT_DISPLAY_FOUND) {
         lost = false;
         redraw = true;
      }
      if (redraw && !lost && al_event_queue_is_empty(queue)) {
         al_set_target_bitmap(bmp);
         al_put_pixel(rand()%w, rand()%h, al_map_rgb(rand()%256, rand()%256, rand()%256));
         al_set_target_backbuffer(dpy);
         al_draw_bitmap(bmp, 0, 0, 0);
         al_flip_display();
         redraw = false;
      }
   }

   return 0;
}

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