API: Add gsk_path_stroke

Add the plumbing that will let us do special-case stroking
for rectangles, circles and other special contours.

There is no implementation yet.

gsk/gskcontour.c

@@ -90,6 +90,9 @@ struct _GskContourClass
                                                  const GskStroke        *stroke,
                                                  graphene_rect_t        *bounds);
   GskContour *          (* reverse)             (const GskContour       *contour);
+  void                  (* add_stroke)          (const GskContour       *contour,
+                                                 GskPathBuilder         *builder,
+                                                 GskStroke              *stroke);
 };
 
 static gsize
@@ -510,6 +513,13 @@ gsk_rect_contour_reverse (const GskContour *contour)
                                                     self->height));
 }
 
+static void
+gsk_rect_contour_add_stroke (const GskContour *contour,
+                             GskPathBuilder   *builder,
+                             GskStroke        *stroke)
+{
+}
+
 static const GskContourClass GSK_RECT_CONTOUR_CLASS =
 {
   sizeof (GskRectContour),
@@ -530,6 +540,7 @@ static const GskContourClass GSK_RECT_CONTOUR_CLASS =
   gsk_rect_contour_get_winding,
   gsk_rect_contour_get_stroke_bounds,
   gsk_rect_contour_reverse,
+  gsk_rect_contour_add_stroke,
 };
 
 GskContour *
@@ -936,6 +947,13 @@ gsk_circle_contour_reverse (const GskContour *contour)
                                  self->start_angle);
 }
 
+static void
+gsk_circle_contour_add_stroke (const GskContour *contour,
+                               GskPathBuilder   *builder,
+                               GskStroke        *stroke)
+{
+}
+
 static const GskContourClass GSK_CIRCLE_CONTOUR_CLASS =
 {
   sizeof (GskCircleContour),
@@ -956,6 +974,7 @@ static const GskContourClass GSK_CIRCLE_CONTOUR_CLASS =
   gsk_circle_contour_get_winding,
   gsk_circle_contour_get_stroke_bounds,
   gsk_circle_contour_reverse,
+  gsk_circle_contour_add_stroke,
 };
 
 GskContour *
@@ -1793,6 +1812,13 @@ gsk_standard_contour_reverse (const GskContour *contour)
   return res;
 }
 
+static void
+gsk_standard_contour_add_stroke (const GskContour *contour,
+                                 GskPathBuilder   *builder,
+                                 GskStroke        *stroke)
+{
+}
+
 static const GskContourClass GSK_STANDARD_CONTOUR_CLASS =
 {
   sizeof (GskStandardContour),
@@ -1813,6 +1839,7 @@ static const GskContourClass GSK_STANDARD_CONTOUR_CLASS =
   gsk_standard_contour_get_winding,
   gsk_standard_contour_get_stroke_bounds,
   gsk_standard_contour_reverse,
+  gsk_standard_contour_add_stroke,
 };
 
 /* You must ensure the contour has enough size allocated,
@@ -1992,6 +2019,14 @@ gsk_contour_get_stroke_bounds (const GskContour *self,
   return self->klass->get_stroke_bounds (self, stroke, bounds);
 }
 
+void
+gsk_contour_add_stroke (const GskContour *self,
+                        GskPathBuilder   *builder,
+                        GskStroke        *stroke)
+{
+  self->klass->add_stroke (self, builder, stroke);
+}
+
 void
 gsk_contour_copy (GskContour       *dest,
                   const GskContour *src)

gsk/gskcontourprivate.h

@@ -100,6 +100,12 @@ void                    gsk_contour_add_segment                 (const GskContou
 gboolean                gsk_contour_get_stroke_bounds           (const GskContour       *self,
                                                                  const GskStroke        *stroke,
                                                                  graphene_rect_t        *bounds);
+void                    gsk_contour_add_stroke                  (const GskContour       *contour,
+                                                                 GskPathBuilder         *builder,
+                                                                 GskStroke              *stroke);
+void                    gsk_contour_default_add_stroke          (const GskContour       *contour,
+                                                                 GskPathBuilder         *builder,
+                                                                 GskStroke              *stroke);
 
 G_END_DECLS
 

gsk/gskpath.c

@@ -1369,3 +1369,28 @@ gsk_path_transform (GskPath      *self,
 
   return gsk_path_builder_free_to_path (data.builder);
 }
+
+/**
+ * gsk_path_stroke:
+ * @self: a `GskPath`
+ * @stroke: stroke parameters
+ *
+ * Create a new path that follows the outline of the area
+ * that would be affected by stroking along @self with
+ * the given stroke parameters.
+ *
+ * Returns: a new `GskPath`
+ */
+GskPath *
+gsk_path_stroke (GskPath   *self,
+                 GskStroke *stroke)
+{
+  GskPathBuilder *builder;
+
+  builder = gsk_path_builder_new ();
+
+  for (int i = 0; i < self->n_contours; i++)
+    gsk_contour_add_stroke (gsk_path_get_contour (self, i), builder, stroke);
+
+  return gsk_path_builder_free_to_path (builder);
+}

gsk/gskpath.h

@@ -117,6 +117,10 @@ GDK_AVAILABLE_IN_ALL
 GskPath *               gsk_path_transform                      (GskPath                *self,
                                                                  GskTransform           *transform);
 
+GDK_AVAILABLE_IN_ALL
+GskPath *               gsk_path_stroke                         (GskPath                *self,
+                                                                 GskStroke              *stroke);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GskPath, gsk_path_unref)
 
 G_END_DECLS