[Freeciv-Dev] Re: (PR#4718) topology cleanup for client autocenter code

["rwetmore@xxxxxxxxxxxx" <rwetmore@xxxxxxxxxxxx>]

Actually, the correct solution is probably even easier and certainly less
code change impact.

I can't actually fathom why you are so in love with this anti-pattern,
that you would do a whole_map_iterate with sqr test for something
that seldom requires more than a handful of iterations at most with an
appropriate iterator.

Cheers,
RossW
=====

     /* Just any known tile will do; search near the middle first. */
+   int x0, y0, xm = map.xsize/2, ym = map.ysize/2;
+   native_to_map_pos(&x0, &y0, xm, ym);
+   iterate_outward(x0, y0, xm + ym, x, y) {
-   iterate_outward(map.xsize / 2, map.ysize / 2,
-                   MAX(map.xsize / 2, map.ysize / 2), x, y) {
       if (tile_get_known(x, y) != TILE_UNKNOWN) {
        center_tile_mapcanvas(x, y);
        goto OUT;
     } iterate_outward_end;
     /* If we get here we didn't find a known tile.
        Refresh a random place to clear the intro gfx. */
     center_tile_mapcanvas(map.xsize / 2, map.ysize / 2);
   OUT:
     ;                          /* do nothing */


Jason Short wrote:
> The code for centering the mapview when the client first connects has 
> lots of fallbacks.
> 
> Currently the second-to-last fallback is to iterate outwards around the 
> center position on the map to find any known tile, and center on that.
> 
> The last fallback is just to center the mapview on the center tile of 
> the map.
> 
> The problem is (map.xsize/2, map.ysize/2) is not the center map position 
> of the map under gen-topologies: it is a native position.  And 
> iterate_outward can't take map.xsize/2, map.ysize/2 as its dimensions 
> since these are native, not map, dimensions.
> 
> The solution is pretty easy; just use native_to_map_pos to do the 
> conversion and whole_map_iterate instead of iterate_outwards.
> 
> An alternative is to have functions to return the dimensions of the map 
> in map coordinates.  But these functions generally have little use and 
> are best avoided IMO.
> 
> jason
> 
> 
> 
> ------------------------------------------------------------------------
> 
> Index: client/climisc.c
> ===================================================================
> RCS file: /home/freeciv/CVS/freeciv/client/climisc.c,v
> retrieving revision 1.119
> diff -u -r1.119 climisc.c
> --- client/climisc.c  2003/07/28 04:00:29     1.119
> +++ client/climisc.c  2003/07/29 17:08:09
> @@ -359,20 +359,28 @@
>      assert(punit != NULL);
>      center_tile_mapcanvas(punit->x, punit->y);
>    } else {
> -    /* Just any known tile will do; search near the middle first. */
> -    iterate_outward(map.xsize / 2, map.ysize / 2,
> -                 MAX(map.xsize / 2, map.ysize / 2), x, y) {
> +    int map_x, map_y, center_map_x, center_map_y, dist = -1;
> +
> +    /* Find the center position on the map. */
> +    native_to_map_pos(&map_x, &map_y, map.xsize / 2, map.ysize / 2);
> +    center_map_x = map_x;
> +    center_map_y = map_y;
> +
> +    /* Look for any known tile - preferably close to the map center.  The
> +     * default is the map center. */
> +    whole_map_iterate(x, y) {
>        if (tile_get_known(x, y) != TILE_UNKNOWN) {
> -     center_tile_mapcanvas(x, y);
> -     goto OUT;
> +     int mydist = sq_map_distance(x, y, center_map_x, center_map_y);
> +
> +     if (dist == -1 || mydist < dist) {
> +       dist = mydist;
> +       map_x = x;
> +       map_y = y;
> +     }
>        }
> -    }
> -    iterate_outward_end;
> -    /* If we get here we didn't find a known tile.
> -       Refresh a random place to clear the intro gfx. */
> -    center_tile_mapcanvas(map.xsize / 2, map.ysize / 2);
> -  OUT:
> -    ;                                /* do nothing */
> +    } whole_map_iterate_end;
> +
> +    center_tile_mapcanvas(map_x, map_y);
>    }
>  }
>