[提问]关于打印预览 [复制链接]

    QPrinter printer(QPrinter::ScreenResolution);
    QPainter painter(&printer);
    QPrintPreviewDialog *dlg = new QPrintPreviewDialog(&printer);
    painter.drawLine(0 , 0 , 400 , 400);
    dlg->exec();
为什么我打印预览里面什么东西都没有？
    QPrinter printer(QPrinter::ScreenResolution);
    printer.setOutputFileName("hello");
    printer.setOutputFormat(QPrinter::PdfFormat);
    QPainter painter(&printer);
    painter.drawLine(0 , 0 , 400 , 400);
这样打印出来是没有问题的
请高手帮忙解决 小弟这里先谢了

连接QPrintPreviewDialog的信号 paintRequested

connect(&preview,SIGNAL(paintRequested(QPrinter *)),this,SLOT(printView(QPrinter *)));

void printView(QPrinter *){

qtableView->render(printer);
}