代码void Index::on_pushButton_2_clicked(){ QList<QTableWidgetItem*> items = ui->tableWidget->selectedItems(); int count = items.count(); if(count!=0){ printer=new QPrinter(); QSettings settings("./saveFile/printsetting.ini",QSettings::IniFormat); settings.setIniCodec("UTF8"); settings.beginGroup("/systemCfg"); int value2 = settings.value("getModeSelect1").toInt(); settings.endGroup(); if(value2==0){ printer->setOrientation(QPrinter::Portrait); printer->setPageSize(QPrinter::A5); } pd = new QPrintPreviewDialog(printer); pd->setWindowFlags(windowFlags()&~Qt::WindowContextHelpButtonHint); if(value2==0||value2==1){ connect(pd,SIGNAL(paintRequested(QPrinter*)),this,SLOT(printPreview1(QPrinter*))); }else{ connect(pd,SIGNAL(paintRequested(QPrinter*)),this,SLOT(printPreview(QPrinter*))); } pd->resize(800,1050); pd->exec(); delete pd; delete printer; } }中怎么使用QPrintPreviewDialog类的静态函数setDefaultPrinter()保留打印预览的设置

在上述代码中，可以在 `printer` 对象创建后，调用 `QPrintPreviewDialog::setDefaultPrinter(printer)` 来设置默认打印机。这样，在打印预览的时候，会自动使用该打印机。

具体实现可以在 `printer` 对象创建之后，添加如下代码：

QPrintPreviewDialog::setDefaultPrinter(printer);

这样，打印预览对话框就会使用该打印机来进行预览和打印。同时，在程序退出时，可以在析构函数中调用 `QPrintPreviewDialog::resetDefaultPrinter()` 来重置默认打印机。

完整代码如下：

void Index::on_pushButton_2_clicked(){
    QList<QTableWidgetItem*> items = ui->tableWidget->selectedItems();
    int count = items.count();
    if(count!=0){
        printer=new QPrinter();
        QSettings settings("./saveFile/printsetting.ini",QSettings::IniFormat);
        settings.setIniCodec("UTF8");
        settings.beginGroup("/systemCfg");
        int value2 = settings.value("getModeSelect1").toInt();
        settings.endGroup();

        if(value2==0){
            printer->setOrientation(QPrinter::Portrait);
            printer->setPageSize(QPrinter::A5);
        }

        // 设置默认打印机
        QPrintPreviewDialog::setDefaultPrinter(printer);

        pd = new QPrintPreviewDialog(printer);
        pd->setWindowFlags(windowFlags()&~Qt::WindowContextHelpButtonHint);
        if(value2==0||value2==1){
            connect(pd,SIGNAL(paintRequested(QPrinter*)),this,SLOT(printPreview1(QPrinter*)));
        }else{
            connect(pd,SIGNAL(paintRequested(QPrinter*)),this,SLOT(printPreview(QPrinter*)));
        }
        pd->resize(800,1050);
        pd->exec();
        delete pd;
        delete printer;
    }
}

Index::~Index()
{
    // 重置默认打印机
    QPrintPreviewDialog::resetDefaultPrinter();
    delete ui;
}