fixed operator- for Rect

modules/core/include/opencv2/core/types.hpp

@@ -1884,8 +1884,11 @@ Rect_<_Tp>& operator += ( Rect_<_Tp>& a, const Size_<_Tp>& b )
 template<typename _Tp> static inline
 Rect_<_Tp>& operator -= ( Rect_<_Tp>& a, const Size_<_Tp>& b )
 {
-    a.width -= b.width;
-    a.height -= b.height;
+    const _Tp width = a.width - b.width;
+    const _Tp height = a.height - b.height;
+    CV_DbgAssert(width >= 0 && height >= 0);
+    a.width = width;
+    a.height = height;
     return a;
 }
 
@@ -1950,6 +1953,15 @@ Rect_<_Tp> operator + (const Rect_<_Tp>& a, const Size_<_Tp>& b)
     return Rect_<_Tp>( a.x, a.y, a.width + b.width, a.height + b.height );
 }
 
+template<typename _Tp> static inline
+Rect_<_Tp> operator - (const Rect_<_Tp>& a, const Size_<_Tp>& b)
+{
+    const _Tp width = a.width - b.width;
+    const _Tp height = a.height - b.height;
+    CV_DbgAssert(width >= 0 && height >= 0);
+    return Rect_<_Tp>( a.x, a.y, width, height );
+}
+
 template<typename _Tp> static inline
 Rect_<_Tp> operator & (const Rect_<_Tp>& a, const Rect_<_Tp>& b)
 {

modules/core/test/test_operations.cpp

@@ -972,6 +972,13 @@ bool CV_OperationsTest::operations1()
         if (sz.width != 10 || sz.height != 20) throw test_excep();
         if (cvSize(sz).width != 10 || cvSize(sz).height != 20) throw test_excep();
 
+        Rect r1(0, 0, 10, 20);
+        Size sz1(5, 10);
+        r1 -= sz1;
+        if (r1.size().width != 5 || r1.size().height != 10) throw test_excep();
+        Rect r2 = r1 - sz1;
+        if (r2.size().width != 0 || r2.size().height != 0) throw test_excep();
+
         Vec<double, 5> v5d(1, 1, 1, 1, 1);
         Vec<double, 6> v6d(1, 1, 1, 1, 1, 1);
         Vec<double, 7> v7d(1, 1, 1, 1, 1, 1, 1);