bo-rectangular: Fix incorrect skipping of colinear eo edges

Fixes test/bug-bo-rectangular

After skipping edges, we need to bd careful to only terminate the box on
a closing edge.

1 files changed, 14 insertions, 17 deletions

diff --git a/src/cairo-bentley-ottmann-rectangular.c b/src/cairo-bentley-ottmann-rectangular.c
index 736762e0d..2cb01cb03 100644
--- a/src/cairo-bentley-ottmann-rectangular.c
+++ b/src/cairo-bentley-ottmann-rectangular.c
@@ -422,9 +422,6 @@ active_edges_to_traps (sweep_line_t	*sweep,
 
 		winding += right->dir;
 		if (winding == 0) {
-		    if (right->next == &sweep->tail)
-			break;
-
 		    /* skip co-linear edges */
 		    if (likely (right->x != right->next->x))
 			break;
@@ -440,30 +437,31 @@ active_edges_to_traps (sweep_line_t	*sweep,
 	    pos = right->next;
 	} while (pos != &sweep->tail);
     } else {
-	edge_t *left, *right;
 	do {
-	    left = pos;
-	    pos = left->next;
-	    do {
-		right = pos;
-		pos = pos->next;
+	    edge_t *right = pos->next;
+	    int count = 0;
 
-		if (right->right != NULL) {
+	    do {
+		/* End all subsumed traps */
+		if (unlikely (right->right != NULL)) {
 		    edge_end_box (sweep,
 				  right, top, do_traps, container);
 		}
 
-		if (pos == &sweep->tail)
-		    break;
+		if (++count & 1) {
+		    /* skip co-linear edges */
+		    if (likely (right->x != right->next->x))
+			break;
+		}
 
-		/* skip co-linear edges */
-		if (right->x != pos->x)
-		    break;
+		right = right->next;
 	    } while (TRUE);
 
 	    edge_start_or_continue_box (sweep,
-					left, right, top,
+					pos, right, top,
 					do_traps, container);
+
+	    pos = right->next;
 	} while (pos != &sweep->tail);
     }
 
@@ -717,7 +715,6 @@ _cairo_bentley_ottmann_tessellate_rectangular_traps (cairo_traps_t *traps,
 
     dump_traps (traps, "bo-rects-traps-out.txt");
 
-
     return status;
 }