extent: add expansion operation

extent.cpp

@@ -66,6 +66,19 @@ extent<T>::area (void) const
     { return w * h; }
 
 
+//-----------------------------------------------------------------------------
+template <typename T>
+extent<T>
+extent<T>::expanded (util::vector<2,T> size) const
+{
+    return {
+        w + size.x,
+        h + size.y
+    };
+}
+
+
+
 //-----------------------------------------------------------------------------
 template <typename T>
 float

extent.hpp

@@ -20,6 +20,8 @@
 #ifndef __UTIL_EXTENT_HPP
 #define __UTIL_EXTENT_HPP
 
+#include "vector.hpp"
+
 #include <iostream>
 
 namespace util {
@@ -37,6 +39,8 @@ namespace util {
         T    area  (void) const;
         T diameter (void) const;
 
+        extent<T> expanded (util::vector<2,T>) const;
+
         float aspect (void) const;
 
         bool empty (void) const;