lookingGlass: Draw a red border around target actor

src/shell-drawing.c

@@ -178,3 +178,38 @@ shell_draw_glow (ClutterCairoTexture *texture,
   cairo_pattern_destroy (gradient);
   cairo_destroy (cr);
 }
+
+static void
+hook_paint_red_border (ClutterActor  *actor,
+                       gpointer       user_data)
+{
+  CoglColor color;
+  ClutterGeometry geom;
+  float width = 2;
+  float x2;
+  float y2;
+
+  cogl_color_set_from_4ub (&color, 0xff, 0, 0, 0xc4);
+  cogl_set_source_color (&color);
+
+  clutter_actor_get_allocation_geometry (actor, &geom);
+  x2 = geom.x + geom.width;
+  y2 = geom.y + geom.height;
+
+  /** clockwise order **/
+  cogl_rectangle (geom.x, geom.y,
+                  x2, geom.y + width);
+  cogl_rectangle (x2 - width, geom.y + width,
+                  x2, y2);
+  cogl_rectangle (x2 - width, y2,
+                  geom.x, y2 - width);
+  cogl_rectangle (geom.x + width, y2 - width,
+                  geom.x, geom.y + width);
+}
+
+guint
+shell_add_hook_paint_red_border (ClutterActor *actor)
+{
+  return g_signal_connect_after (G_OBJECT (actor), "paint",
+                                 G_CALLBACK (hook_paint_red_border), NULL);
+}

src/shell-drawing.h

@@ -23,6 +23,8 @@ void shell_draw_glow (ClutterCairoTexture *texture,
                       double green,
                       double alpha);
 
+guint shell_add_hook_paint_red_border (ClutterActor *actor);
+
 G_END_DECLS
 
 #endif /* __SHELL_GLOBAL_H__ */