Qt导出PDF文件：使用QPdfWriter绘制PDF和使用QPrintPreviewDialog为绘制的PDF文件提供预览之后输出PDF

一、使用QPdfWriter绘制PDF

void MainWindow::exportPdf()
{
    //一、选择保存pdf文件路径
    QString sPath = QFileDialog::getSaveFileName(this, tr("另存为"), "/", tr("Text Files (*.pdf)"));
    if(sPath.isEmpty())
    {
        return;
    }
    qDebug() << sPath;

    //二、创建pdf文件
    QFile pdfFile(sPath);
    pdfFile.open(QIODevice::WriteOnly);

    //三、创建生成pdf类，作为绘图设备
    QPdfWriter *pPdfWriter = new QPdfWriter(&pdfFile);
    pPdfWriter->setResolution(300);
    pPdfWriter->setPageSize(QPagedPaintDevice::A4);
    pPdfWriter->setPageMargins(QMarginsF(30, 30, 30, 30));

    //四、开始绘制PDF
    paintPdf(pPdfWriter);

    delete pPdfWriter;
    pdfFile.close();

    //通过其它PDF阅读器来打开刚刚绘制的PDF
    QDesktopServices::openUrl(QUrl::fromLocalFile(sPath));
}

二、使用QPrintPreviewDialog预览绘制的PDF然后输出

在生成的打印预览界面点击打印按钮，就会弹出导出PDF窗口，选择要PDF文件要保存的路径，然后保存即可。

如下图所示：

（1）创建QPrintPreviewDialog对象

　　 QPrintPreviewDialog *m_pPrintPreviewDlg = new QPrintPreviewDialog()；

（2）将paintRequested()信号连接到槽

    connect(m_pPrintPreviewDlg, &QPrintPreviewDialog::paintRequested, this, &MainWindow::slot_previewPdf);

（3）设置默认打印机的一些参数，最重要的是设置打印机输出格式为PDF

    m_pPrintPreviewDlg->printer()->setResolution(300);
    m_pPrintPreviewDlg->printer()->setOrientation(QPrinter::Portrait);
    //设置打印机输出格式为PDF格式
    m_pPrintPreviewDlg->printer()->setOutputFormat(QPrinter::PdfFormat);
    m_pPrintPreviewDlg->printer()->setPaperSize(QPagedPaintDevice::A4);
    m_pPrintPreviewDlg->printer()->setPageMargins(QMarginsF(30, 30, 30, 30));

（4）槽函数

void MainWindow::slot_previewPdf(QPrinter *printer)
{
    paintPdf(printer);
}

（5）绘制PDF函数

void MainWindow::paintPdf(QPagedPaintDevice *device)
{
    QPainter *pPainter = new QPainter(device);
    qDebug() << pPainter->viewport();
    int nPdfWidth = pPainter->viewport().width();
    int nPdfHeight = pPainter->viewport().height();

    //绘制标题
    int y = 10;
    pPainter->setFont(QFont("宋体", 18, 36));
    pPainter->drawText(QRect(0, y, nPdfWidth, 100), Qt::AlignCenter, tr("实验操作记录报告"));

    //绘制报告相关信息
    y += 200;
    pPainter->setFont(QFont("宋体", 12, 20));
    int nLineSpace = 100;
    int nLineHeight = 60;
    pPainter->drawText(QRect(100, y, nPdfWidth, nLineHeight), Qt::AlignLeft, QString("实验编号：%1").arg("19990926001"));
    y += nLineSpace;
    pPainter->drawText(QRect(100, y, nPdfWidth, nLineHeight), Qt::AlignLeft, QString("操作仪器：%1").arg("TMachine9568"));
    y += nLineSpace;
    pPainter->drawText(QRect(100, y, nPdfWidth, nLineHeight), Qt::AlignLeft, QString("操作用户：%1").arg("Dr.Miss"));
    y += nLineSpace;
    pPainter->drawText(QRect(100, y, nPdfWidth, nLineHeight), Qt::AlignLeft, QString("开始时间：%1").arg("1999-09-26 17:50"));
    y += nLineSpace;
    pPainter->drawText(QRect(100, y, nPdfWidth, nLineHeight), Qt::AlignLeft, QString("结束时间：%1").arg("1999-09-26 22:30"));

    //绘制每个操作记录的各项标题 （标题宽的比例为 序号：操作时间：操作说明：试管和试剂信息 = 2：5：5：10）
    y += 150;
    pPainter->setFont(QFont("宋体", 14, 28));
    int nUnitW = nPdfWidth / (2 + 5 + 5+ 10);

    int nNoWidth = nUnitW * 2;

    int nTimeX = nNoWidth;
    int nTimeWidth = nUnitW * 5;

    int nExplainX = nTimeX + nTimeWidth;
    int nExplainWidth = nUnitW * 5;

    int nRgInfoX = nExplainX + nExplainWidth;
    int nRgInfoW = nUnitW * 10;

    nLineHeight = 80;
    pPainter->drawText(QRect(0, y, nNoWidth, nLineHeight), Qt::AlignCenter, "序号");
    pPainter->drawText(QRect(nTimeX, y, nTimeWidth, nLineHeight), Qt::AlignCenter, "操作时间");
    pPainter->drawText(QRect(nExplainX, y, nExplainWidth, nLineHeight), Qt::AlignCenter, "操作说明");
    pPainter->drawText(QRect(nRgInfoX, y, nRgInfoW, nLineHeight), Qt::AlignCenter, "试管和试剂信息");

    //绘制一条分隔线
    y += 100;
    pPainter->setPen(QPen(QBrush(QColor(144, 166,188)), 8));
    pPainter->drawLine(QLineF(0, y, nPdfWidth, y));

    //绘制染色操作记录,假设此刻有25条记录需要绘制
    for(int i = 0; i < 25; ++i)
    {
        //判断是否应该另起一页(320:根据计算,绘制每条记录大概需要320点）
        if(y + 320 >= nPdfHeight)
        {
            device->newPage();
            y = 10;
        }

        y += 50;
        pPainter->setFont(QFont("宋体", 12, 20));
        pPainter->setPen(QPen(QBrush(QColor(0, 0, 0)), 1));

        nLineSpace = 80;
        nLineHeight = 50;

        pPainter->drawText(QRect(0, y, nNoWidth, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft, QString("%1").arg(i + 1));
        pPainter->drawText(QRect(nTimeX, y, nTimeWidth, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft, "1999-09-26 18:27");
        pPainter->drawText(QRect(nExplainX, y, nExplainWidth, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft, "需加试剂DC9混合");

        //试管和试剂信息的每行需列出2项信息 宽度比例为7:3
        nUnitW = nRgInfoW / (7 + 3);

        int nLeftX = nRgInfoX;
        int nLeftW = nUnitW * 6;

        int nRightX = nLeftX + nLeftW;
        int nRightW = nUnitW * 4;

        pPainter->drawText(QRect(nLeftX, y, nLeftW, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft,
                           QString("试管ID: %1").arg("15bb00226fa"));
        pPainter->drawText(QRect(nRightX, y, nRightW, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft,
                           QString("试管位置号: %1").arg(18));

        y += nLineSpace;
        pPainter->drawText(QRect(nLeftX, y, nLeftW, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft,
                           QString("添加试剂1: %1").arg("AC856"));
        pPainter->drawText(QRect(nRightX, y, nRightW, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft,
                           QString("添加量：%1 μL").arg(150));

        y += nLineSpace;
        pPainter->drawText(QRect(nLeftX, y, nLeftW, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft,
                           QString("添加试剂2: %1").arg("SFH51"));
        pPainter->drawText(QRect(nRightX, y, nRightW, nLineHeight), Qt::AlignVCenter | Qt::AlignLeft,
                           QString("添加量：%1 μL").arg(80));

        y += 70;
        pPainter->setPen(QPen(QBrush(QColor(166, 188, 222)), 3));
        pPainter->drawLine(QLineF(0, y, nPdfWidth, y));
    }

    delete pPainter;
}

 参考：https://www.cnblogs.com/lifexy/p/12620647.html