关键代码

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QToolBar>
#include <QMessageBox>

class QMenuBar;
class QToolBar;
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    
    
    ui->setupUi(this);

    QAction* openAction = new QAction("连接",this);
    openAction->setShortcut(QKeySequence::Open);//动作的快捷键；比如：open快捷键 Ctrl+O（Qt的QKeySequence定义的）
    openAction->setStatusTip("打开文件");//添加状态栏的提示语句

    openAction->setIcon(QIcon(":/res/break-link.jpg"));//添加这句代码，添加图标

    auto file = menuBar()->addMenu("菜单栏");
    file->addAction(openAction);
    QToolBar* toolBar = addToolBar("工具栏");

    QWidget *spacer = new QWidget(this);
    spacer->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);
    toolBar->addWidget(spacer);

    // 此种方式为文字显示在图标下面，如图所示
    toolBar->setToolButtonStyle(Qt::ToolButtonTextUnderIcon);
    toolBar->setIconSize(QSize(40,50));
    toolBar->addAction(openAction);
    connect(openAction,SIGNAL(triggered()),this,SLOT(link()));


    QAction* svg = new QAction("首页",this);
    svg->setShortcut(QKeySequence::Back);
    svg->setStatusTip("首页");
    svg->setIcon(QIcon(QPixmap(":/res/icon-home page.svg")));//添加这句代码，添加图标
    toolBar->addAction(svg);
    toolBar->setMovable(false);
    connect(svg,SIGNAL(triggered()),this,SLOT(homePage()));


    pixmap = new QPixmap (":/res/bg.png");
}

void MainWindow::homePage() {
    
    
    QMessageBox::information(this,"提示","点击首页");
}
void MainWindow::link() {
    
    
    QMessageBox::information(this,"提示","点击连接");
}

void MainWindow::setBg() {
    
    
    qDebug()<<"重置窗口大小";
    QPalette palette;
    palette.setBrush(backgroundRole(), QBrush(*pixmap));
    setPalette(palette);
    palette.setBrush(QPalette::Window,QBrush(pixmap->scaled(this->size(), Qt::IgnoreAspectRatio,Qt::SmoothTransformation)));
    setPalette(palette);
}

void MainWindow::resizeEvent(QResizeEvent *event) {
    
    
    setBg();
}

MainWindow::~MainWindow()
{
    
    
    delete ui;
    delete pixmap;
}

效果

完整代码示例

https://download.csdn.net/download/qq_44575789/85394829