实现了打印和预览功能

QPrinter printer(QPrinter::HighResolution);
    QPrintDialog dialog(&printer,QApplication::activeWindow());
    if (dialog.exec()==QDialog::Accepted){
        QPainter p(&printer);
        foreach(pageScene, pageSceneVector){
            pageScene->render(&p, printer.paperRect(), sceneRect);
            if(pageScene != pageSceneVector.last())
                printer.newPage();
        }
    }

预览功能
主函数里添加

  QPrinter printer(QPrinter::HighResolution);
    //自定义纸张大小
    printer.setPageSize(QPrinter::A4);

    QPrintPreviewDialog preview(&printer, this);
     preview.setWindowTitle("打印预览");
   preview.setWindowFlags(Qt::Window);
   preview.setMinimumSize(1200,800);
    connect(&preview, SIGNAL(paintRequested(QPrinter*)),&rp, SLOT(printPreviewSlot(QPrinter*)));
    preview.exec ();

//  rp 为 实现打印预览功能的类引用
调用函数
void QTEWordExpress::printPreviewSlot(QPrinter *printer)
{
    
    QPainter p(printer);
    foreach(pageScene, pageSceneVector){
        pageScene->render(&p, printer->paperRect(), sceneRect);
        if(pageScene != pageSceneVector.last())
            printer->newPage();
   }
}