clutter/util: Add functions for managing cairo and clutter rects

Utility functions to easily convert from ClutterRect to cairo int rects and
vice-versa.

And add ability to offset a cairo rect.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/3

clutter/clutter/clutter-private.h

@@ -249,6 +249,14 @@ void  _clutter_util_fully_transform_vertices (const CoglMatrix    *modelview,
 void _clutter_util_rect_from_rectangle (const cairo_rectangle_int_t *src,
                                         ClutterRect                 *dest);
 
+void _clutter_util_rectangle_int_extents (const ClutterRect     *src,
+                                          cairo_rectangle_int_t *dest);
+
+void _clutter_util_rectangle_offset (const cairo_rectangle_int_t *src,
+                                     int                          x,
+                                     int                          y,
+                                     cairo_rectangle_int_t       *dest);
+
 void _clutter_util_rectangle_union (const cairo_rectangle_int_t *src1,
                                     const cairo_rectangle_int_t *src2,
                                     cairo_rectangle_int_t       *dest);

clutter/clutter/clutter-util.c

@@ -120,6 +120,32 @@ void _clutter_util_rect_from_rectangle (const cairo_rectangle_int_t *src,
   };
 }
 
+void _clutter_util_rectangle_int_extents (const  ClutterRect    *src,
+                                          cairo_rectangle_int_t *dest)
+{
+  ClutterRect tmp = *src;
+
+  clutter_rect_clamp_to_pixel (&tmp);
+
+  *dest = (cairo_rectangle_int_t) {
+    .x = tmp.origin.x,
+    .y = tmp.origin.y,
+    .width = tmp.size.width,
+    .height = tmp.size.height,
+  };
+}
+
+void _clutter_util_rectangle_offset (const cairo_rectangle_int_t *src,
+                                     int                          x,
+                                     int                          y,
+                                     cairo_rectangle_int_t       *dest)
+{
+  *dest = *src;
+
+  dest->x += x;
+  dest->y += y;
+}
+
 /*< private >
  * _clutter_util_rectangle_union:
  * @src1: first rectangle to union