navigator view draw viewport rect

navigatorview.h

@@ -3,14 +3,24 @@
 
 #include <QGraphicsView>
 
+class GraphicsView;
 class NavigatorView : public QGraphicsView
 {
     Q_OBJECT
 public:
     NavigatorView(QWidget *parent = nullptr);
 
+    void setMainView(GraphicsView *mainView);
+
+public slots:
+    void updateMainViewportRegion();
+
 private:
     void wheelEvent(QWheelEvent *event) override;
+    void paintEvent(QPaintEvent *event) override;
+
+    QPolygon m_viewportRegion;
+    QGraphicsView *m_mainView = nullptr;
 };
 
 #endif // NAVIGATORVIEW_H