轉載 ： https://blog.csdn.net/linux_ever/article/details/50120617

QMainWindow有選單欄，工具欄，狀態列；

可以將QWidget作為QMainWindow的中間部位的一個部件；

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLabel>
#include "myview.h"//在mainwindow上再新增一個視窗
#include <QSystemTrayIcon>//托盤

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    void paintEvent(QPaintEvent *);
    void mousePressEvent(QMouseEvent *);
    bool event(QEvent *);
    QLabel * _label;
    MyView * _view;//把要顯示的東西都放在這個視窗部件裡面；mainWindow起到封裝的作用
    QMenu * _menu;//用於右鍵彈出選單
    QSystemTrayIcon * _icon;//托盤圖示
    void slotActivated(QSystemTrayIcon::ActivationReason);
signals:
    
public slots:
    void slotOpen();
    void slotSave();
};

#endif // MAINWINDOW_H
 

mainwindow.cpp

#include "mainwindow.h"
#include <QApplication>
#include <QMenu>//選單類
#include <QMenuBar>//選單欄
#include <QAction>//選單項,是一個可以觸發的東西
#include <QFileDialog>
#include <QDebug>
#include <QToolBar>
#include <QStatusBar>
#include <QPainter>
#include <QPixmap>
#include <QMouseEvent>
#include <QCursor>//滑鼠當前的位置
#include <QIcon>
#include <QEvent>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    /*新增選單*/
    QMenuBar * pMenuBar = menuBar();
    QMenu *menu = pMenuBar->addMenu("File");
    _menu = menu;

    QAction *openAction = menu->addAction("&Open", this, SLOT(slotOpen()), QKeySequence::Open);
    QAction *saveAction = menu->addAction("&Save", this, SLOT(slotSave()), QKeySequence::Save);
    menu->addSeparator();
    QAction *closeAction = menu->addAction("&Exit", this, SLOT(close()), QKeySequence::Close);

    /*新增工具欄*/
    QToolBar *toolBar = this->addToolBar("MyToolBar");//新增一個工具欄
    toolBar->addAction(openAction);
    toolBar->addAction(saveAction);
    toolBar->addAction(closeAction);

    /*新增狀態列*/
    QStatusBar *pstatusBar = this->statusBar();
    pstatusBar->addWidget(_label = new QLabel("OK"));
    _label->setText("<font color = red>Processing...</font>");

    /*mainwindow中別的控制元件佔用了之後，剩下的區域都是CentralWidget的*/
    _view = new MyView;
    this->setCentralWidget(_view);

    /*托盤*/
    _icon = new QSystemTrayIcon;
    _icon->setIcon(QIcon("../1.png"));
    _icon->setToolTip("This is my tray test");
    _icon->show();//顯示該托盤圖示
    _icon->setContextMenu(menu);
    connect(_icon, SIGNAL(activated(QSystemTrayIcon::ActivationReason)), this, SLOT(slotActivated(QSystemTrayIcon::ActivationReason)));
}

//這個函式的功能也沒有實現
void MainWindow::slotActivated(QSystemTrayIcon::ActivationReason reason)
{
    if (reason == QSystemTrayIcon::Trigger){
        if (this->isHidden()) this->show();
        else this->isHidden();
    }
}

//這個函式的功能沒有實現
bool MainWindow::event(QEvent *event)
{
    if(event->type() == QEvent::Close){
        return false;
    }
    return QMainWindow::event(event);
}

void MainWindow::paintEvent(QPaintEvent *)
{
    QPainter p(this);
    p.drawPixmap(QPointF(0, 0),QPixmap("../1.png"));
}

void MainWindow::mousePressEvent(QMouseEvent *ev)
{
    if(ev->button() == Qt::RightButton)
        _menu->exec(QCursor::pos());
}

void MainWindow::slotSave()
{
    QFileDialog::getSaveFileName();

}

void MainWindow::slotOpen()
{
    QString strFile = QFileDialog::getOpenFileName();
    qDebug() << strFile;
}


int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    MainWindow w;
    w.setGeometry(300, 130, 700, 500);
    w.show();

    app.exec();
}
 

myview.h

#ifndef MYVIEW_H
#define MYVIEW_H

#include <QWidget>

class MyView : public QWidget
{
    Q_OBJECT
public:
    explicit MyView(QWidget *parent = 0);
    void paintEvent(QPaintEvent *);
signals:
    
public slots:
    
};

#endif // MYVIEW_H

myview.cpp

#include "myview.h"
#include <QPainter>

MyView::MyView(QWidget *parent) :
    QWidget(parent)
{
}


void MyView::paintEvent(QPaintEvent *)
{
    QPainter p(this);
    p.fillRect(rect(), Qt::red);
}