gstate: Speed up stroked path extents

We can skip the intermediate evaluation of the trapezoids for
determining the extents of a stroked path by using the relatively new
functions for computing the contours of the stroke. Then we can simply
use the bbox of the points within the contours to retrieve the path
extents - which is already provided by the polygon holding the contours
of the stroke. This provides a faster result with less numerical
inaccuracy due to fewer stages required in the computation

References: https://bugs.freedesktop.org/show_bug.cgi?id=62375
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 12 insertions, 12 deletions

diff --git a/src/cairo-gstate.c b/src/cairo-gstate.c
index 6319471ac..b8caa63f1 100644
--- a/src/cairo-gstate.c
+++ b/src/cairo-gstate.c
@@ -1462,19 +1462,19 @@ _cairo_gstate_stroke_extents (cairo_gstate_t	 *gstate,
     }
 
     if (status == CAIRO_INT_STATUS_UNSUPPORTED) {
-	cairo_traps_t traps;
-
-	_cairo_traps_init (&traps);
-	status = _cairo_path_fixed_stroke_polygon_to_traps (path,
-							    &gstate->stroke_style,
-							    &gstate->ctm,
-							    &gstate->ctm_inverse,
-							    gstate->tolerance,
-							    &traps);
-	empty = traps.num_traps == 0;
+	cairo_polygon_t polygon;
+
+	_cairo_polygon_init (&polygon, NULL, 0);
+	status = _cairo_path_fixed_stroke_to_polygon (path,
+						      &gstate->stroke_style,
+						      &gstate->ctm,
+						      &gstate->ctm_inverse,
+						      gstate->tolerance,
+						      &polygon);
+	empty = polygon.num_edges == 0;
 	if (! empty)
-	    _cairo_traps_extents (&traps, &extents);
-	_cairo_traps_fini (&traps);
+	    extents = polygon.extents;
+	_cairo_polygon_fini (&polygon);
     }
     if (! empty) {
 	_cairo_gstate_extents_to_user_rectangle (gstate, &extents,