diff --git a/src/core/geometry_func.cpp b/src/core/geometry_func.cpp
index 162f2eae57..11722c0a4d 100644
--- a/src/core/geometry_func.cpp
+++ b/src/core/geometry_func.cpp
@@ -26,3 +26,17 @@ Dimension maxdim(const Dimension &d1, const Dimension &d2)
 	d.height = max(d1.height, d2.height);
 	return d;
 }
+
+/**
+ * Compute sum of both dimensions.
+ * @param d1 First dimension.
+ * @param d2 Second dimension.
+ * @return The sum of both dimensions.
+ */
+Dimension adddim(const Dimension &d1, const Dimension &d2)
+{
+	Dimension d;
+	d.width  = d1.width + d2.width;
+	d.height = d1.height + d2.height;
+	return d;
+}
diff --git a/src/core/geometry_func.hpp b/src/core/geometry_func.hpp
index cd136488ac..09d9d08b12 100644
--- a/src/core/geometry_func.hpp
+++ b/src/core/geometry_func.hpp
@@ -13,5 +13,6 @@
 #include "geometry_type.hpp"
 
 Dimension maxdim(const Dimension &d1, const Dimension &d2);
+Dimension adddim(const Dimension &d1, const Dimension &d2);
 
 #endif /* GEOMETRY_FUNC_HPP */