Math: added Geometry::Rectangle::translated().

The Rectangle class needs to be generalized, but this function was needed
for a long time.

src/Math/Geometry/Rectangle.h

@@ -132,6 +132,11 @@ template<class T> class Rectangle {
         /** @brief %Rectangle height */
         constexpr T height() const { return _topRight.y() - _bottomLeft.y(); }
 
+        /** @brief Translated rectangle */
+        Rectangle<T> translated(const Vector2<T>& vec) {
+            return {_bottomLeft + vec, _topRight + vec};
+        };
+
     private:
         Vector2<T> _bottomLeft;
         Vector2<T> _topRight;

src/Math/Geometry/Test/RectangleTest.cpp

@@ -44,6 +44,8 @@ class RectangleTest: public Corrade::TestSuite::Tester {
         void compare();
         void size();
 
+        void translated();
+
         void debug();
         void configuration();
 };
@@ -63,6 +65,8 @@ RectangleTest::RectangleTest() {
               &RectangleTest::compare,
               &RectangleTest::size,
 
+              &RectangleTest::translated,
+
               &RectangleTest::debug,
               &RectangleTest::configuration});
 }
@@ -144,6 +148,11 @@ void RectangleTest::size() {
     CORRADE_COMPARE(rect.height(), 7);
 }
 
+void RectangleTest::translated() {
+    CORRADE_COMPARE(Rectanglei({34, 23}, {47, 30}).translated({-17, 40}),
+                    Rectanglei({17, 63}, {30, 70}));
+}
+
 void RectangleTest::debug() {
     std::ostringstream o;
     Debug(&o) << Rectanglei({34, 23}, {47, 30});