29、Qt使用上下文菜单（右键菜单）-编程知识

说明：使用四种方式实现鼠标右击界面，显示出菜单，菜单上有两个动作，选择两个动作，分别打印“111”和“222”。

界面样式如下：

一、方法1：重写鼠标事件mousePressEvent

.h中的代码如下：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();protected:void mousePressEvent(QMouseEvent *event);private:void createContextMenu();private slots:void onDebug1();void onDebug2();private:Ui::MainWindow *ui;QMenu *m_menu;
};
#endif // MAINWINDOW_H

.cpp中的代码如下：

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QDebug>
#include <QContextMenuEvent>
#include <QMouseEvent>MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);createContextMenu();
}MainWindow::~MainWindow()
{delete ui;
}/** 重写鼠标事件
* @brief MainWindow::mousePressEvent
* @param event
*/
void MainWindow::mousePressEvent(QMouseEvent *event)
{if(event->button() == Qt::RightButton) //鼠标右键单击{m_menu->exec(QCursor::pos()); //显示菜单}
}/** 初始化菜单
* @brief MainWindow::createContextMenu
*/
void MainWindow::createContextMenu()
{m_menu = new QMenu(this);QAction *action1 = new QAction;action1->setText("打印1");connect(action1, &QAction::triggered, this, &MainWindow::onDebug1);m_menu->addAction(action1);m_menu->addSeparator(); //分隔符QAction *action2 = new QAction;action2->setText("打印2");connect(action2, &QAction::triggered, this, &MainWindow::onDebug2);m_menu->addAction(action2);
}/** 打印1对应的槽函数
* @brief MainWindow::onDebug1
*/
void MainWindow::onDebug1()
{qDebug() << "111";
}/** 打印2对应的槽函数
* @brief MainWindow::onDebug2
*/
void MainWindow::onDebug2()
{qDebug() << "222";
}

二、方法2：setContextMenuPolicy(Qt::DefaultContextMenu)

setContextMenuPolicy()的参数设置为Qt::DefaultContextMenu，右击界面会触发contextMenuEvent()事件。

.h中的代码如下：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();protected:void contextMenuEvent(QContextMenuEvent *event);private:void createContextMenu();private slots:void onDebug1();void onDebug2();private:Ui::MainWindow *ui;QMenu *m_menu;
};
#endif // MAINWINDOW_H

.cpp中的代码如下：

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QDebug>
#include <QContextMenuEvent>
#include <QMouseEvent>MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);createContextMenu();this->setContextMenuPolicy(Qt::DefaultContextMenu);
}MainWindow::~MainWindow()
{delete ui;
}/** 上下文菜单事件
* @brief MainWindow::contextMenuEvent
* @param event
*/
void MainWindow::contextMenuEvent(QContextMenuEvent *event)
{Q_UNUSED(event);m_menu->exec(QCursor::pos()); //显示菜单
}/** 初始化菜单
* @brief MainWindow::createContextMenu
*/
void MainWindow::createContextMenu()
{m_menu = new QMenu(this);QAction *action1 = new QAction;action1->setText("打印1");connect(action1, &QAction::triggered, this, &MainWindow::onDebug1);m_menu->addAction(action1);m_menu->addSeparator(); //分隔符QAction *action2 = new QAction;action2->setText("打印2");connect(action2, &QAction::triggered, this, &MainWindow::onDebug2);m_menu->addAction(action2);
}/** 打印1对应的槽函数
* @brief MainWindow::onDebug1
*/
void MainWindow::onDebug1()
{qDebug() << "111";
}/** 打印1对应的槽函数
* @brief MainWindow::onDebug2
*/
void MainWindow::onDebug2()
{qDebug() << "222";
}

三、方法3：setContextMenuPolicy(Qt::CustomContextMenu);

setContextMenuPolicy()的参数设置为Qt::CustomContextMenu，右击界面会发射on_XXX_customContextMenuRequested(const QPoint &pos)信号。

.h中的代码如下：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private:void createContextMenu();private slots:void onDebug1();void onDebug2();void on_MainWindow_customContextMenuRequested(const QPoint &pos);private:Ui::MainWindow *ui;QMenu *m_menu;
};
#endif // MAINWINDOW_H

.cpp中的代码如下：

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QDebug>
#include <QContextMenuEvent>
#include <QMouseEvent>MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);createContextMenu();this->setContextMenuPolicy(Qt::CustomContextMenu);
}MainWindow::~MainWindow()
{delete ui;
}/** 初始化菜单
* @brief MainWindow::createContextMenu
*/
void MainWindow::createContextMenu()
{m_menu = new QMenu(this);QAction *action1 = new QAction;action1->setText("打印1");connect(action1, &QAction::triggered, this, &MainWindow::onDebug1);m_menu->addAction(action1);m_menu->addSeparator(); //分隔符QAction *action2 = new QAction;action2->setText("打印2");connect(action2, &QAction::triggered, this, &MainWindow::onDebug2);m_menu->addAction(action2);
}/** 打印1对应的槽函数
* @brief MainWindow::onDebug1
*/
void MainWindow::onDebug1()
{qDebug() << "111";
}/** 打印1对应的槽函数
* @brief MainWindow::onDebug2
*/
void MainWindow::onDebug2()
{qDebug() << "222";
}/** on_类名_customContextMenuRequested
* @brief MainWindow::on_MainWindow_customContextMenuRequested
* @param pos
*/
void MainWindow::on_MainWindow_customContextMenuRequested(const QPoint &pos)
{QPoint gloPos = this->mapToGlobal(pos);m_menu->exec(gloPos);
}

四、方法4：setContextMenuPolicy(Qt::ActionsContextMenu);

setContextMenuPolicy()的参数设置为Qt::ActionsContextMenu，右击界面会将其 QWidget::actions() 显示为上下文菜单。

.h中的代码如下：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private:void createContextMenu();private slots:void onDebug1();void onDebug2();private:Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

.cpp中的代码如下：

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QDebug>
#include <QContextMenuEvent>
#include <QMouseEvent>MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);createContextMenu();this->setContextMenuPolicy(Qt::ActionsContextMenu);
}MainWindow::~MainWindow()
{delete ui;
}/** 初始化菜单
* @brief MainWindow::createContextMenu
*/
void MainWindow::createContextMenu()
{QAction *action1 = new QAction;action1->setText("打印1");connect(action1, &QAction::triggered, this, &MainWindow::onDebug1);this->addAction(action1);//this->addSeparator(); //分隔符QAction *action2 = new QAction;action2->setText("打印2");connect(action2, &QAction::triggered, this, &MainWindow::onDebug2);this->addAction(action2);
}/** 打印1对应的槽函数
* @brief MainWindow::onDebug1
*/
void MainWindow::onDebug1()
{qDebug() << "111";
}/** 打印1对应的槽函数
* @brief MainWindow::onDebug2
*/
void MainWindow::onDebug2()
{qDebug() << "222";
}