enhancement:maptool:slice big polygons into smaller parts

navit/maptool/itembin_slicer.c

@@ -791,8 +791,8 @@ void itembin_nicer_slicer(struct tile_info *info, struct item_bin *ib, FILE *ref
     long long * id;
     int is_relation=0;
 
-    /* for now only slice polygons. */
-    if (ib->type < type_area) {
+    /* for now only slice polygons and things > min. */
+    if (ib->type < type_area || min <= tile_len(buffer)) {
         tile_write_item_to_tile(info, ib, reference, buffer);
         return;
     }
@@ -829,8 +829,8 @@ void itembin_nicer_slicer(struct tile_info *info, struct item_bin *ib, FILE *ref
     sp.buffer = buffer;
     sp.number=0;
 
-    /* for all tiles in range...*/
-    while (strcmp(tilecode,tileend) != 0) {
+    /* for all tiles in range. Allow this to overflow if tile_len(buffer) == 0*/
+    do {
         struct rect bbox;
         /* get tile rectangle */
         tile_bbox(tilecode, &bbox, 0);
@@ -847,7 +847,7 @@ void itembin_nicer_slicer(struct tile_info *info, struct item_bin *ib, FILE *ref
         /* next tile */
         next_tile(tilecode);
         sp.number ++;
-    }
+    } while (strcmp(tilecode,tileend) != 0);
     itembin_slicerpolygon_free(&sp);
 }
 

navit/maptool/tile.c

@@ -334,22 +334,29 @@ void tile_write_item_to_tile(struct tile_info *info, struct item_bin *ib, FILE *
 }
 
 void tile_write_item_minmax(struct tile_info *info, struct item_bin *ib, FILE *reference, int min, int max) {
+    /*TODO: make slice_trigger and slice_target configurable by commandline parameter.
+     * bonus: find out why there is a 'min' parameter here
+     */
+    int slice_trigger = 4;
+    int slice_target = 7;
     struct rect r;
     char buffer[1024];
     bbox((struct coord *)(ib+1), ib->clen/2, &r);
     buffer[0]='\0';
     tile(&r, info->suffix, buffer, max, overlap, NULL);
-
-    /*TODO: make '4' and '7' configurable by commandline parameter.
-     * bonus: find out why there is a 'min' parameter here
-     */
-    if((ib->type >= type_area) && (ib->type != type_poly_water_tiled) && (tile_len(buffer) < 4)) {
+    if((ib->type >= type_area) && (ib->type != type_poly_water_tiled) && (tile_len(buffer) < slice_trigger)) {
         /* Get a new reference tile before slicing ommitting the overlap. This is required
          * as we want to slice without overlap and therefore we do not miss parts of the
          * item residing in the overlap area */
         buffer[0]='\0';
         tile(&r, info->suffix, buffer, max, 0, NULL);
-        itembin_nicer_slicer(info, ib, reference, buffer, 7);
+        /* it sometimes ahppens that objects falling into big tile using overlaps falls into way smaller
+         * one without overlaps. If this happens, there is no need to slice. Just put the item into the
+         * tile found without overlap. */
+        if(tile_len(buffer) < slice_trigger)
+            itembin_nicer_slicer(info, ib, reference, buffer, slice_target);
+        else
+            tile_write_item_to_tile(info, ib, reference, buffer);
     } else {
         tile_write_item_to_tile(info, ib, reference, buffer);
     }