widget_accessor.hpp - minimize dependencies

modules/viz/include/opencv2/viz/widget_accessor.hpp

 #pragma once
 
-#include <opencv2/viz/widgets.hpp>
+#include <opencv2/core/cvdef.h>
 #include <vtkSmartPointer.h>
 #include <vtkLODActor.h>
 
 namespace temp_viz
 {
+    class Widget;
+
     //The class is only that depends on VTK in its interface.
-    //It is indended for those user who want to develop own widgets system using VTK library API.
+    //It is indended for those users who want to develop own widgets system using VTK library API.
     struct CV_EXPORTS WidgetAccessor
     {
-        static  vtkSmartPointer<vtkLODActor> getActor(const Widget &widget);
+        static vtkSmartPointer<vtkLODActor> getActor(const Widget &widget);
     };
 }

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

@@ -6,7 +6,7 @@
 namespace temp_viz
 {
     /////////////////////////////////////////////////////////////////////////////
-    /// brief The base class for all widgets
+    /// The base class for all widgets
     class CV_EXPORTS Widget
     {
     public:

modules/viz/src/types.cpp

 #include <opencv2/viz/types.hpp>
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////
-/// cv::Color
+/// cv::viz::Color
 
 temp_viz::Color::Color() : Scalar(0, 0, 0) {}
 temp_viz::Color::Color(double gray) : Scalar(gray, gray, gray) {}