[HighGUI] Updated mouse wheel delta to reside within the 'flags' variable. Updated C++ API.

modules/highgui/src/window.cpp

@@ -216,6 +216,11 @@ void cv::setMouseCallback( const String& windowName, MouseCallback onMouse, void
     cvSetMouseCallback(windowName.c_str(), onMouse, param);
 }
 
+int cv::getMouseWheelDelta( int flags )
+{
+    return CV_GET_WHEEL_DELTA(flags);
+}
+
 int cv::startWindowThread()
 {
     return cvStartWindowThread();

modules/highgui/src/window_w32.cpp

@@ -1392,7 +1392,7 @@ MainWindowProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
 
           // Set the wheel delta of mouse wheel to be in the upper word of 'event'
           int delta = GET_WHEEL_DELTA_WPARAM(wParam);
-          event |= (delta << 16);
+          flags |= (delta << 16);
 
           POINT pt;
           {