QT::打印事件

void doPrint();
void doPrintPreview();
void printPreview(QPrinter *printer);
void createPdf();

ui->setupUi(this);
QAction *action_print = new QAction(tr("打印"),this);
QAction *action_printPreview = new QAction(tr("打印预览"),this);
QAction *action_pdf = new QAction(tr("生成pdf"),this);
connect(action_print,SIGNAL(triggered()),this,SLOT(doPrint()));

connect(action_printPreview,SIGNAL(triggered()),this,SLOT(doPrintPreview()));
connect(action_pdf,SIGNAL(triggered()),this,SLOT(createPdf()));

ui->mainToolBar->addAction(action_print);
ui->mainToolBar->addAction(action_printPreview);
ui->mainToolBar->addAction(action_pdf);

void MainWindow::doPrint()
{
    // 创建打印机对象
    QPrinter printer;
    // 创建打印对话框
    QPrintDialog dlg(&printer, this);

    //如果编辑器中有选中区域，则打印选中区域
    if (ui->textEdit->textCursor().hasSelection())
        dlg.addEnabledOption(QAbstractPrintDialog::PrintSelection);

    // 如果在对话框中按下了打印按钮，则执行打印操作
    if (dlg.exec() == QDialog::Accepted) {
        ui->textEdit->print(&printer);
    }
}

打印预览
void MainWindow::doPrintPreview()
{
    QPrinter printer;
    // 创建打印预览对话框
    QPrintPreviewDialog preview(&printer, this);

    // 当要生成预览页面时，发射paintRequested()信号
    connect(&preview,SIGNAL(paintRequested(QPrinter*)),
                this,SLOT(printPreview(QPrinter*)));                  

    preview.exec();
}

void MainWindow::printPreview(QPrinter *printer)
{
    ui->textEdit->print(printer);
}

// 生成PDF文件
void MainWindow::createPdf()
{
    QString fileName = QFileDialog::getSaveFileName(this, tr("导出PDF文件"),QString(), "*.pdf");
    if (!fileName.isEmpty()) 
    {
        // 如果文件后缀为空，则默认使用.pdf
        if (QFileInfo(fileName).suffix().isEmpty())
            fileName.append(".pdf");

        QPrinter printer;
        // 指定输出格式为pdf
        printer.setOutputFormat(QPrinter::PdfFormat);
        printer.setOutputFileName(fileName);
        ui->textEdit->print(&printer);
    }
}