Solve Rect overflow issues.

Fow now, it is possible to define valid rectangle for which some
functions overflow (e.g. br(), ares() ...).
This patch fixes the intersection operator so that it works with
any rectangle.

modules/core/test/test_misc.cpp

@@ -784,4 +784,36 @@ TEST(Core_Check, testSize_1)
 }
 
 
+template <typename T> class Rect_Test : public testing::Test {};
+
+TYPED_TEST_CASE_P(Rect_Test);
+
+// Reimplement C++11 std::numeric_limits<>::lowest.
+template<typename T> T cv_numeric_limits_lowest();
+template<> int cv_numeric_limits_lowest<int>() { return INT_MIN; }
+template<> float cv_numeric_limits_lowest<float>() { return -FLT_MAX; }
+template<> double cv_numeric_limits_lowest<double>() { return -DBL_MAX; }
+
+TYPED_TEST_P(Rect_Test, Overflows) {
+  typedef Rect_<TypeParam> R;
+  TypeParam num_max = std::numeric_limits<TypeParam>::max();
+  TypeParam num_lowest = cv_numeric_limits_lowest<TypeParam>();
+  EXPECT_EQ(R(0, 0, 10, 10), R(0, 0, 10, 10) & R(0, 0, 10, 10));
+  EXPECT_EQ(R(5, 6, 4, 3), R(0, 0, 10, 10) & R(5, 6, 4, 3));
+  EXPECT_EQ(R(5, 6, 3, 2), R(0, 0, 8, 8) & R(5, 6, 4, 3));
+  // Test with overflowing dimenions.
+  EXPECT_EQ(R(5, 0, 5, 10), R(0, 0, 10, 10) & R(5, 0, num_max, num_max));
+  // Test with overflowing dimensions for floats/doubles.
+  EXPECT_EQ(R(num_max, 0, num_max / 4, 10), R(num_max, 0, num_max / 2, 10) & R(num_max, 0, num_max / 4, 10));
+  // Test with overflowing coordinates.
+  EXPECT_EQ(R(), R(20, 0, 10, 10) & R(num_lowest, 0, 10, 10));
+  EXPECT_EQ(R(), R(20, 0, 10, 10) & R(0, num_lowest, 10, 10));
+  EXPECT_EQ(R(), R(num_lowest, 0, 10, 10) & R(0, num_lowest, 10, 10));
+}
+REGISTER_TYPED_TEST_CASE_P(Rect_Test, Overflows);
+
+typedef ::testing::Types<int, float, double> RectTypes;
+INSTANTIATE_TYPED_TEST_CASE_P(Negative_Test, Rect_Test, RectTypes);
+
+
 }} // namespace