Index: trunk/src/polygon.c
===================================================================
--- trunk/src/polygon.c	(revision 16964)
+++ trunk/src/polygon.c	(revision 16965)
@@ -1301,6 +1301,23 @@
 	return pcb_poly_init_clip_prog(Data, layer, p, NULL, NULL);
 }
 
+pcb_cardinal_t pcb_poly_num_clears(pcb_data_t *data, pcb_layer_t *layer, pcb_poly_t *polygon)
+{
+	pcb_cardinal_t res;
+	void (*old_cb)(void *ctx);
+
+	if (layer->is_bound)
+		layer = layer->meta.bound.real;
+
+	old_cb = pcb_poly_clip_prog;
+	pcb_poly_clip_prog = NULL;
+
+	res = clearPoly(data, layer, polygon, NULL, NULL, 1);
+
+	pcb_poly_clip_prog = old_cb;
+	return res;
+}
+
 /* --------------------------------------------------------------------------
  * remove redundant polygon points. Any point that lies on the straight
  * line between the points on either side of it is redundant.
Index: trunk/src/polygon.h
===================================================================
--- trunk/src/polygon.h	(revision 16964)
+++ trunk/src/polygon.h	(revision 16965)
@@ -93,6 +93,11 @@
    giving the caller a chance to draw a progress bar */
 int pcb_poly_init_clip_prog(pcb_data_t *Data, pcb_layer_t *layer, pcb_poly_t *p, void (*cb)(void *ctx), void *ctx);
 
+/* Return the number of subtractions that have to be executed by a
+   pcb_poly_init_clip() on the given polygon */
+pcb_cardinal_t pcb_poly_num_clears(pcb_data_t *data, pcb_layer_t *layer, pcb_poly_t *polygon);
+
+
 pcb_bool pcb_poly_is_point_in_p(pcb_coord_t, pcb_coord_t, pcb_coord_t, pcb_poly_t *);
 pcb_bool pcb_poly_is_point_in_p_ignore_holes(pcb_coord_t, pcb_coord_t, pcb_poly_t *);
 pcb_bool_t pcb_is_point_in_convex_quad(pcb_vector_t p, pcb_vector_t *q);