[cairo-path-fixed] Exponentially enlarge cairo_path_buf_t.

Allocate subsequent path bufs twice as large as the previous buf,
whilst still embedding a small initial buf into cairo_path_fixed_t
that handles the most frequent usage.

1 files changed, 13 insertions, 7 deletions

diff --git a/src/cairo-path-fixed-private.h b/src/cairo-path-fixed-private.h
index 6e1300abe..f506c3449 100644
--- a/src/cairo-path-fixed-private.h
+++ b/src/cairo-path-fixed-private.h
@@ -46,18 +46,24 @@ enum cairo_path_op {
 typedef char cairo_path_op_t;
 
 /* make cairo_path_fixed fit a 512 bytes.  about 50 items */
-#define CAIRO_PATH_BUF_SIZE ((512 - 12 * sizeof (void*)) \
-			   / (sizeof (cairo_point_t) + sizeof (cairo_path_op_t)))
+#define CAIRO_PATH_BUF_SIZE ((512 - 4 * sizeof (void*) - sizeof (cairo_path_buf_t)) \
+			   / (2 * sizeof (cairo_point_t) + sizeof (cairo_path_op_t)))
 
 typedef struct _cairo_path_buf {
     struct _cairo_path_buf *next, *prev;
+    int buf_size;
     int num_ops;
     int num_points;
 
-    cairo_path_op_t op[CAIRO_PATH_BUF_SIZE];
-    cairo_point_t points[CAIRO_PATH_BUF_SIZE];
-
+    cairo_path_op_t *op;
+    cairo_point_t *points;
 } cairo_path_buf_t;
+typedef struct _cairo_path_buf_fixed {
+    cairo_path_buf_t base;
+
+    cairo_path_op_t op[CAIRO_PATH_BUF_SIZE];
+    cairo_point_t points[2 * CAIRO_PATH_BUF_SIZE];
+} cairo_path_buf_fixed_t;
 
 struct _cairo_path_fixed {
     cairo_point_t last_move_point;
@@ -65,8 +71,8 @@ struct _cairo_path_fixed {
     unsigned int has_current_point	: 1;
     unsigned int has_curve_to		: 1;
 
-    cairo_path_buf_t *buf_tail;
-    cairo_path_buf_t  buf_head[1];
+    cairo_path_buf_t       *buf_tail;
+    cairo_path_buf_fixed_t  buf_head;
 };
 
 #endif /* CAIRO_PATH_FIXED_PRIVATE_H */