feat: add floating edge

src/gui/network/NetworkGraphicsView.h

@@ -1,20 +1,27 @@
 #pragma once
+#include <qgraphicsitem.h>
 #include <qwidget.h>
 #include <QGraphicsView>
 #include <QGraphicsScene>
 
+class Network;
+
 class NetworkGraphicsView
 : public QGraphicsView
 {
 public:
-    NetworkGraphicsView(QWidget *parent = nullptr, QGraphicsScene* scene = nullptr);
+    NetworkGraphicsView(QWidget *parent = nullptr, Network* network=nullptr, QGraphicsScene* scene = nullptr);
 private:
     QPointF panStartPos;
     void initUI();
+    QGraphicsScene* scene_;
+    Network* network_;
 
 protected:
     void mouseMoveEvent(QMouseEvent *mouseEvent) override;
     void mousePressEvent(QMouseEvent *event) override;
+    void leftMousePress(QMouseEvent *event);
+    QGraphicsItem* getItemAtClick(QMouseEvent *event);
     void wheelEvent(QWheelEvent *event) override;
     // void mouseReleaseEvent(QMouseEvent *event) override;