[gtk/path-work-rebased: 1007/1045] path: Add gsk_path_builder_add_ellipse()

[Matthias Clasen <matthiasc src gnome org>]

commit e72ff9f84fb697630eece251ac57884ca5ce4d45
Author: Benjamin Otte <otte redhat com>
Date:   Fri Dec 25 21:31:06 2020 +0100

    path: Add gsk_path_builder_add_ellipse()

 gsk/gskpathbuilder.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 gsk/gskpathbuilder.h |  4 ++++
 2 files changed, 50 insertions(+)
---
diff --git a/gsk/gskpathbuilder.c b/gsk/gskpathbuilder.c
index 89d37894e7..7ea5ba8d7e 100644
--- a/gsk/gskpathbuilder.c
+++ b/gsk/gskpathbuilder.c
@@ -446,6 +446,52 @@ gsk_path_builder_add_circle (GskPathBuilder         *builder,
   gsk_path_builder_add_contour (builder, contour);
 }
 
+/**
+ * gsk_path_builder_add_ellipse:
+ * @builder: a `GskPathBuilder`
+ * @center: the center point of the ellipse
+ * @radius: the radius of the ellipse in x/y direction
+ *
+ * Adds an ellipse with the given @center and the @radius in
+ * x/y direction.
+ **/
+void
+gsk_path_builder_add_ellipse (GskPathBuilder         *builder,
+                              const graphene_point_t *center,
+                              const graphene_size_t  *radius)
+{
+  const float weight = sqrt(0.5f);
+  graphene_point_t pts[8];
+
+  g_return_if_fail (builder != NULL);
+  g_return_if_fail (center != NULL);
+  g_return_if_fail (radius != NULL);
+
+  pts[0] = GRAPHENE_POINT_INIT (center->x + radius->width / 2,
+                                center->y);
+  pts[1] = GRAPHENE_POINT_INIT (center->x + radius->width / 2,
+                                center->y + radius->height / 2);
+  pts[2] = GRAPHENE_POINT_INIT (center->x,
+                                center->y + radius->height / 2);
+  pts[3] = GRAPHENE_POINT_INIT (center->x - radius->width / 2,
+                                center->y + radius->height / 2);
+  pts[4] = GRAPHENE_POINT_INIT (center->x - radius->width / 2,
+                                center->y);
+  pts[5] = GRAPHENE_POINT_INIT (center->x - radius->width / 2,
+                                center->y - radius->height / 2);
+  pts[6] = GRAPHENE_POINT_INIT (center->x,
+                                center->y - radius->height / 2);
+  pts[7] = GRAPHENE_POINT_INIT (center->x + radius->width / 2,
+                                center->y - radius->height / 2);
+
+  gsk_path_builder_move_to (builder, pts[0].x, pts[0].y);
+  gsk_path_builder_conic_to (builder, pts[1].x, pts[1].y, pts[2].x, pts[2].y, weight);
+  gsk_path_builder_conic_to (builder, pts[3].x, pts[3].y, pts[4].x, pts[4].y, weight);
+  gsk_path_builder_conic_to (builder, pts[5].x, pts[5].y, pts[6].x, pts[6].y, weight);
+  gsk_path_builder_conic_to (builder, pts[7].x, pts[7].y, pts[0].x, pts[0].y, weight);
+  gsk_path_builder_close (builder);
+}
+
 /**
  * gsk_path_builder_move_to:
  * @builder: a `GskPathBuilder`
diff --git a/gsk/gskpathbuilder.h b/gsk/gskpathbuilder.h
index 15bf3c469c..a28d90100d 100644
--- a/gsk/gskpathbuilder.h
+++ b/gsk/gskpathbuilder.h
@@ -62,6 +62,10 @@ GDK_AVAILABLE_IN_ALL
 void                    gsk_path_builder_add_circle             (GskPathBuilder         *builder,
                                                                  const graphene_point_t *center,
                                                                  float                   radius);
+GDK_AVAILABLE_IN_ALL
+void                    gsk_path_builder_add_ellipse            (GskPathBuilder         *builder,
+                                                                 const graphene_point_t *center,
+                                                                 const graphene_size_t  *radius);
 /* next function implemented in gskpathmeasure.c */
 GDK_AVAILABLE_IN_ALL
 void                    gsk_path_builder_add_segment            (GskPathBuilder         *builder,