reverted widget reference count in order to avoid memory leak

modules/viz/include/opencv2/viz/widgets.hpp

@@ -14,6 +14,9 @@ namespace cv
         {
         public:
             Widget();
+            Widget(const Widget& other);
+            Widget& operator=(const Widget& other);
+            ~Widget();
             
             static Widget fromPlyFile(const String &file_name);
             
@@ -25,6 +28,9 @@ namespace cv
             class Impl;
             Impl *impl_;
             friend struct WidgetAccessor;
+            
+            void create();
+            void release();
         };
 
         /////////////////////////////////////////////////////////////////////////////

modules/viz/src/widget.cpp

@@ -7,11 +7,52 @@ class cv::viz::Widget::Impl
 {
 public:
     vtkSmartPointer<vtkProp> prop;
+    int ref_counter;
     
     Impl() : prop(0) {}
 };
 
-cv::viz::Widget::Widget() : impl_( new Impl() ) { }
+cv::viz::Widget::Widget() : impl_(0) 
+{ 
+    create(); 
+}
+
+cv::viz::Widget::Widget(const Widget& other) : impl_(other.impl_) 
+{ 
+    if (impl_) CV_XADD(&impl_->ref_counter, 1);
+}
+
+cv::viz::Widget& cv::viz::Widget::operator=(const Widget& other)
+{
+    if (this != &other)
+    {
+        release();
+        impl_ = other.impl_;
+        if (impl_) CV_XADD(&impl_->ref_counter, 1);
+    }
+    return *this;
+}
+
+cv::viz::Widget::~Widget() 
+{ 
+    release();
+}
+
+void cv::viz::Widget::create()
+{
+    if (impl_) release();
+    impl_ = new Impl();
+    impl_->ref_counter = 1;
+}
+
+void cv::viz::Widget::release()
+{
+    if (impl_ && CV_XADD(&impl_->ref_counter, -1) == 1)
+    {
+        delete impl_;
+        impl_ = 0;
+    }
+}
 
 cv::viz::Widget cv::viz::Widget::fromPlyFile(const String &file_name)
 {