static nodelist_t*
reduce_edge_crossings(nodelist_t* list, Agraph_t* subg)
{
int i, crossings, origCrossings;
crossings = count_all_crossings(list, subg);
if(crossings == 0) return list;
for(i = 0; i < CROSS_ITER; i++) {
origCrossings = crossings;
list = reduce (list, subg, &crossings);
/* return if no crossings or no improvement */
if ((origCrossings == crossings) || (crossings == 0))
return list;
}
return list;
}
/* reduce:
* Attempt to reduce edge crossings by moving nodes.
* Original crossing count is in cnt; final count is returned there.
* list is the original list; return the best list found.
*/
static nodelist_t *reduce(nodelist_t * list, Agraph_t * subg, int *cnt)
{
Agnode_t *curnode;
Agedge_t *e;
Agnode_t *neighbor;
nodelist_t *listCopy;
int crossings, j, newCrossings;
crossings = *cnt;
for (curnode = agfstnode(subg); curnode;
curnode = agnxtnode(subg, curnode)) {
/* move curnode next to its neighbors */
for (e = agfstedge(subg, curnode); e;
e = agnxtedge(subg, e, curnode)) {
neighbor = e->tail;
if (neighbor == curnode)
neighbor = e->head;
for (j = 0; j < 2; j++) {
listCopy = cloneNodelist(list);
insertNodelist(list, curnode, neighbor, j);
newCrossings = count_all_crossings(list, subg);
if (newCrossings < crossings) {
crossings = newCrossings;
freeNodelist(listCopy);
if (crossings == 0) {
*cnt = 0;
return list;
}
} else {
freeNodelist(list);
list = listCopy;
}
}
}
}
*cnt = crossings;
return list;
}
