[AL] Is it a Problem with GDI?

[Sherjeel A. <she...@ya...>]

Hi
 
Allegro is not just only a game programming library but also an excellent graphics library. I've Allegro 4.2.2 built with VS2005 SP1. I've WinXP SP3 on a Pentium4 2.26Ghz. However I'm facing an issue running the Allegro applications in GDI mode. A small program (much more rarely) exhibiting the behavior is as following. It is also strange that more lengthy code produces more chances of crash.
 
#include <allegro.h>
#include <winalleg.h> // For including <window.h>
 
volatile bool bCloseBttnPressed = false;
void close_button_handler(void) { bCloseBttnPressed = true; }
 
int main(void)
{
 int i;
 int my_key;
 
 BITMAP *pBmpMiceSprite;
 BITMAP *pBmpChar[2];
 
 allegro_init();
 
 install_timer();
 install_keyboard();
 install_mouse();
 
 set_gdi_color_format();
 set_color_depth(desktop_color_depth());
 set_gfx_mode(GFX_GDI, 750, 500, 0, 0);
 
 set_display_switch_mode(SWITCH_BACKGROUND); // Don't pause when in background
 //set_display_switch_mode(SWITCH_BACKAMNESIA);
 
 set_window_title("My Allegro Application");
 
 set_close_button_callback(close_button_handler);
 
 show_mouse(screen);
 
 pBmpMiceSprite = create_bitmap(32,32);
 rectfill(pBmpMiceSprite,0,0,31,31,bitmap_mask_color(pBmpMiceSprite));
 for(i = 1; i < 15; i += 3) circle(pBmpMiceSprite,15,15,i,makecol(255,0,0));
 
 pBmpChar[0] = create_bitmap(750,500);
 rectfill(pBmpChar[0],0,0,749,499,makecol(0,255,0));
 
 pBmpChar[1] = create_bitmap(750,500);
 rectfill(pBmpChar[1],0,0,749,499,makecol(0,0,255));
 
 set_mouse_sprite(pBmpMiceSprite);
 
 i = 0;
 my_key = NULL;
 while( (my_key != 27) && (bCloseBttnPressed == false))
 {
  scare_mouse();
  
  acquire_screen();
  blit(pBmpChar[i],screen,0,0,0,0,750,500);
  release_screen();
 
  unscare_mouse();
 
  rest(1); // Play nice with OS Scheduler
  
  i = (i+1) % 2;
  if(keypressed()) my_key = (readkey() & 0xFF); // Interested in only ASCII
 }
 
 set_mouse_sprite(NULL); // Change back allegro's arrow pointer
 
 destroy_bitmap(pBmpMiceSprite);
 destroy_bitmap(pBmpChar[0]);
 destroy_bitmap(pBmpChar[1]);
 
 return 0;
}
END_OF_MAIN()

The application sometimes (though very rare) hangs when it exits or when I switch to some other application. I've tried to debug the situation. Many many times it is deep inside windows own system files like ntdll.dll but sometimes I catch it in the following:
 
When exiting application:
wwnd.c (Allegro Source) - line number 470,
result = MsgWaitForMultipleObjects(_win_input_events, _win_input_event_id, FALSE, INFINITE, QS_ALLINPUT);
 
When switching application and also sometimes when exiting:
thread.c (C Runtime Library) - line number 293,
( (void(__CLRCALL_OR_CDECL *)(void *))(((_ptiddata)ptd)->_initaddr) ) ( ((_ptiddata)ptd)->_initarg );
 
I've brought the application on other systems but with varying frequency the problem persists there too. I was thinking there might be something wrong by me building the allegro but the problem persists even with the pre-built allegro libraries downloaded from the Allegro Website. I've also tried versions 4.2.0 and 4.3.10 but found no difference. As I've already stated that it appears very rare but I want to avoid this situation to write quality software. What are your recommendations? Please share.