diff options
| -rw-r--r-- | src/cairo-tor-scan-converter.c | 36 |
1 files changed, 14 insertions, 22 deletions
diff --git a/src/cairo-tor-scan-converter.c b/src/cairo-tor-scan-converter.c index 0b7a9174..d9c9ce89 100644 --- a/src/cairo-tor-scan-converter.c +++ b/src/cairo-tor-scan-converter.c @@ -1150,27 +1150,28 @@ active_list_init(struct active_list *active) static struct edge * merge_sorted_edges (struct edge *head_a, struct edge *head_b) { - struct edge *head, **next; + struct edge *head, **next, *prev; int32_t x; - if (head_a == NULL) - return head_b; - + prev = head_a->prev; next = &head; if (head_a->x.quo <= head_b->x.quo) { head = head_a; } else { head = head_b; + head_b->prev = prev; goto start_with_b; } do { x = head_b->x.quo; while (head_a != NULL && head_a->x.quo <= x) { + prev = head_a; next = &head_a->next; head_a = head_a->next; } + head_b->prev = prev; *next = head_b; if (head_a == NULL) return head; @@ -1178,10 +1179,12 @@ merge_sorted_edges (struct edge *head_a, struct edge *head_b) start_with_b: x = head_a->x.quo; while (head_b != NULL && head_b->x.quo <= x) { + prev = head_b; next = &head_b->next; head_b = head_b->next; } + head_a->prev = prev; *next = head_a; if (head_b == NULL) return head; @@ -1206,8 +1209,8 @@ start_with_b: * (we start with a small sorted list and keep merging other lists of the same size to it). */ static struct edge * -sort_edges (struct edge *list, - unsigned int level, +sort_edges (struct edge *list, + unsigned int level, struct edge **head_out) { struct edge *head_other, *remaining; @@ -1215,36 +1218,28 @@ sort_edges (struct edge *list, head_other = list->next; - /* Single element list -> return */ if (head_other == NULL) { *head_out = list; return NULL; } - /* Unroll the first iteration of the following loop (halves the number of calls to merge_sorted_edges): - * - Initialize remaining to be the list containing the elements after the second in the input list. - * - Initialize *head_out to be the sorted list containing the first two element. - */ remaining = head_other->next; if (list->x.quo <= head_other->x.quo) { *head_out = list; - /* list->next = head_other; */ /* The input list is already like this. */ head_other->next = NULL; } else { *head_out = head_other; + head_other->prev = list->prev; head_other->next = list; + list->prev = head_other; list->next = NULL; } for (i = 0; i < level && remaining; i++) { - /* Extract a sorted list of the same size as *head_out - * (2^(i+1) elements) from the list of remaining elements. */ remaining = sort_edges (remaining, i, &head_other); *head_out = merge_sorted_edges (*head_out, head_other); } - /* *head_out now contains (at most) 2^(level+1) elements. */ - return remaining; } @@ -1307,13 +1302,7 @@ inline static void active_list_merge_edges_from_bucket(struct active_list *active, struct edge *edges) { - struct edge *edge, *prev; - active->head.next = merge_unsorted_edges (active->head.next, edges); - - /* update links within sort? */ - for (edge = &active->head, prev = NULL; edge; prev = edge, edge = edge->next) - edge->prev = prev; } inline static void @@ -1327,7 +1316,10 @@ polygon_fill_buckets (struct active_list *active, while (edge) { struct edge *next = edge->next; int suby = edge->ytop - y; + if (buckets[suby]) + buckets[suby]->prev = edge; edge->next = buckets[suby]; + edge->prev = NULL; buckets[suby] = edge; if (edge->height_left < min_height) min_height = edge->height_left; |