widget.h

#ifndef WIDGET_H

#define WIDGET_H

#include <QWidget>

#include <QMenu>

class Widget : public QWidget

{

Q_OBJECT

public:

　　Widget(QWidget *parent = nullptr);

　　~Widget();

private:

　　void contextMenuEvent(QContextMenuEvent *event) override;

　　void initMenu(void);

private:

　　QMenu *p_Menu;

};

#endif // WIDGET_H

widget.cpp

#include "widget.h"

#include <QMessageBox>

#include <QAction>

Widget::Widget(QWidget *parent): QWidget(parent)

{

　　this->setContextMenuPolicy(Qt::DefaultContextMenu);

　　initMenu();

}

Widget::~Widget()

{

}

void Widget::initMenu(void)

{

　　p_Menu = new QMenu(this);

　　QAction *act1 = new QAction("act1");

　　QAction *act2 = new QAction("act2");

　　QAction *act3 = new QAction("act3");

　　QAction *act4 = new QAction("act4");

　　p_Menu->addAction(act1);

　　p_Menu->addAction(act2);

　　p_Menu->addAction(act3);

　　p_Menu->addAction(act4);

　　connect(act1, &QAction::triggered, this, [=]{QMessageBox::information(this, "title", "ac1");});

　　connect(act2, &QAction::triggered, this, [=]{QMessageBox::information(this, "title", "ac2");});

　　connect(act3, &QAction::triggered, this, [=]{QMessageBox::information(this, "title", "ac3");});

　　connect(act4, &QAction::triggered, this, [=]{QMessageBox::information(this, "title", "ac4");});

}

void Widget::contextMenuEvent(QContextMenuEvent *event)

{

　　Q_UNUSED(event);

　　p_Menu->exec(QCursor::pos());

}