如何打印Qt对话框或窗口？

#include <QDialog>
#include <QPrinter>
#include <QPainter>

class MyDialog : public QDialog
{
    Q_OBJECT

public:
    MyDialog(QWidget *parent = nullptr);

private slots:
    void printDialog();

private:
    QPrinter *printer;
    QPainter *painter;
};

MyDialog::MyDialog(QWidget *parent)
    : QDialog(parent)
{
    // 初始化打印机和绘图对象
    printer = new QPrinter();
    painter = new QPainter();
}

void MyDialog::printDialog()
{
    // 设置打印机的打印范围为当前对话框
    printer->setOrientation(QPrinter::Portrait);
    printer->setPaperSize(QPrinter::A4);
    printer->setPageMargins(10, 10, 10, 10, QPrinter::Millimeter);

    // 开始打印
    painter->begin(printer);

    // 绘制对话框
    painter->drawWidget(this);

    // 结束打印
    painter->end();
}