[stroke] Handle degenerate stroke extents

If the stroke is degenerate, i.e. the path consists only of a single
move-to and no edges, then the stroke may be visible due to end-capping
(as opposed to fills which are empty). So we also need to pad out the
extents around the current point for the degenerate case.

1 files changed, 13 insertions, 18 deletions

diff --git a/src/cairo-path-bounds.c b/src/cairo-path-bounds.c
index 1a3cdf06b..d3bc449a9 100644
--- a/src/cairo-path-bounds.c
+++ b/src/cairo-path-bounds.c
@@ -52,13 +52,6 @@ _cairo_path_bounder_init (cairo_path_bounder_t *bounder)
 }
 
 static void
-_cairo_path_bounder_fini (cairo_path_bounder_t *bounder)
-{
-    bounder->has_initial_point = FALSE;
-    bounder->has_point = FALSE;
-}
-
-static void
 _cairo_path_bounder_add_point (cairo_path_bounder_t *bounder,
 			       const cairo_point_t *point)
 {
@@ -79,7 +72,6 @@ _cairo_path_bounder_add_point (cairo_path_bounder_t *bounder,
 	bounder->extents.p1.y = point->y;
 	bounder->extents.p2.x = point->x;
 	bounder->extents.p2.y = point->y;
-
 	bounder->has_point = TRUE;
     }
 }
@@ -195,8 +187,6 @@ _cairo_path_fixed_approximate_clip_extents (const cairo_path_fixed_t *path,
 	extents->x = extents->y = 0;
 	extents->width = extents->height = 0;
     }
-
-    _cairo_path_bounder_fini (&bounder);
 }
 
 /* A slightly better approximation than above - we actually decompose the
@@ -225,8 +215,6 @@ _cairo_path_fixed_approximate_fill_extents (const cairo_path_fixed_t *path,
 	extents->x = extents->y = 0;
 	extents->width = extents->height = 0;
     }
-
-    _cairo_path_bounder_fini (&bounder);
 }
 
 void
@@ -253,8 +241,6 @@ _cairo_path_fixed_fill_extents (const cairo_path_fixed_t	*path,
 	extents->x = extents->y = 0;
 	extents->width = extents->height = 0;
     }
-
-    _cairo_path_bounder_fini (&bounder);
 }
 
 /* Adjusts the fill extents (above) by the device-space pen.  */
@@ -288,12 +274,23 @@ _cairo_path_fixed_approximate_stroke_extents (const cairo_path_fixed_t *path,
 	bounder.extents.p2.y += _cairo_fixed_from_double (dy);
 
 	_cairo_box_round_to_rectangle (&bounder.extents, extents);
+    } else if (bounder.has_initial_point) {
+	double dx, dy;
+
+	/* accommodate capping of degenerate paths */
+
+	_cairo_stroke_style_max_distance_from_path (style, ctm, &dx, &dy);
+
+	bounder.extents.p1.x = bounder.current_point.x - _cairo_fixed_from_double (dx);
+	bounder.extents.p2.x = bounder.current_point.x + _cairo_fixed_from_double (dx);
+	bounder.extents.p1.y = bounder.current_point.y - _cairo_fixed_from_double (dy);
+	bounder.extents.p2.y = bounder.current_point.y + _cairo_fixed_from_double (dy);
+
+	_cairo_box_round_to_rectangle (&bounder.extents, extents);
     } else {
 	extents->x = extents->y = 0;
 	extents->width = extents->height = 0;
     }
-
-    _cairo_path_bounder_fini (&bounder);
 }
 
 cairo_status_t
@@ -354,6 +351,4 @@ _cairo_path_fixed_bounds (const cairo_path_fixed_t *path,
 	*x2 = 0.0;
 	*y2 = 0.0;
     }
-
-    _cairo_path_bounder_fini (&bounder);
 }