osx man page for get_desktop_resolution

get_desktop_resolution(3alleg4) 				  Allegro manual				   get_desktop_resolution(3alleg4)

NAME
       get_desktop_resolution - Finds out the desktop resolution. Allegro game programming library.

SYNOPSIS
       #include <allegro.h>

       int get_desktop_resolution(int *width, int *height);

DESCRIPTION
       Finds out the currently selected desktop resolution. You can use this information to avoid creating windows bigger than the current resolu-
       tion.  This is especially important for some windowed drivers which are unable to create windows bigger than the desktop. Each parameter is
       a pointer to an integer where one dimension of the screen will be stored.

       Under  some  OSes,  switching  to a full screen graphics mode may automatically change the desktop resolution. You have, therefore, to call
       this function before setting any graphics mode in order to retrieve the real desktop resolution. Example:

	  int width, height;

	  allegro_init();
	  ...
	  if (get_desktop_resolution(&width, &height) == 0) {
	     /* Got the resolution correctly */
	  }

RETURN VALUE
       Returns zero on success, or a negative number if this information is not available or does not apply, in which case the	values	stored	in
       the variables you provided for `width' and `height' are undefined.

SEE ALSO
       desktop_color_depth(3alleg4), set_gfx_mode(3alleg4)

Allegro 							   version 4.4.2				   get_desktop_resolution(3alleg4)