gfx_mode_select_filter man page

gfx_mode_select_filter — Even more extended version of the graphics mode selection dialog. Allegro game programming library.

Synopsis

#include <allegro.h>

int gfx_mode_select_filter(int *card, int *w, int *h, int *color_depth, int (*filter)(int, int, int, int));

Description

Even more extended version of the graphics mode selection dialog, which allows the programmer to customize the contents of the dialog and the user to select the color depth as well as the resolution and hardware driver. `filter' will be passed (card, w, h, color_depth) quadruplets and must return 0 to let the specified quadruplet be added to the list of displayed modes.

As with gfx_mode_select, the values stored at the addresses passed to the function will be used as suggestions for the initial selections in the dialog, defaulting to the first entry in each list if the values are not found. Initialize the data stored at the addresses passed to the function to the value of 0 or -1 if you want to ensure that the initial selection for each list will be the first entry.

If the dialog is OK'd, it stores the selections at the addresses passed to the function.

Example usage :

ret = gfx_mode_select_filter(&card, &w, &h, &color_depth, user_filter);
if (ret) {/* User okayed dialog or user_filter removed all modes */
   if (card == GFX_NONE) {
      // No modes available
      *card = 0;/* Make sure not to leave *card == GFX_NONE */
      return -1;
   }
   /* Handle changing to new mode here... */
   
} else {/* User cancelled dialog or there was an error (unlikely) */
   if (card == GFX_NONE) {
      /* Error, probably out of memory */
      *card = 0;/* Make sure not to leave *card == GFX_NONE */
      return -2;
   }
   /* Carry on in current graphics mode if that is acceptable */
}

Return Value

Returns zero if the user cancelled the dialog or an error occurred. In the case of an error then *card is assigned the value GFX_NONE. The functions return non-zero if the user made a selection OR if all the modes were filtered out. In the case that all of the modes were filtered out, then *card is assigned the value GFX_NONE. This means you should NOT initialize the *card to the value of GFX_NONE, as it could interfere with determining the proper return value.

See Also

gfx_mode_select(3), gfx_mode_select_ex(3), set_color_depth(3), set_gfx_mode(3), gui_fg_color(3)

Referenced By

get_gfx_mode_type(3), gfx_mode_select(3), gfx_mode_select_ex(3).

version 4.4.2 Allegro Allegro manual