图片过大，怎样设置分页打印 [复制链接]

    QPrinter printer(QPrinter::ScreenResolution);

    QPrintDialog *printDialog = new QPrintDialog(&printer, this);

    if (printDialog->exec() == QDialog::Accepted)
     {
         QPainter painter(&printer);painter.setClipping(true);
         QRect rect = painter.viewport();
         QSize size = QPixmap::grabWidget(scrollAreaWidgetContents,scrollAreaWidgetContents->rect()).toImage().size();
         scrollAreaWidgetContents->size().scale(rect.size(), Qt::KeepAspectRatio);
         painter.setViewport(rect.x()-(size.width()-740)/2, rect.y(), size.width(), size.height());
         painter.setWindow(QPixmap::grabWidget(scrollAreaWidgetContents,scrollAreaWidgetContents->rect()).toImage().rect());
         painter.drawImage(0, 0, QPixmap::grabWidget(scrollAreaWidgetContents,scrollAreaWidgetContents->rect()).toImage());
     }

我画出的图片太高，打印只打印一页，显示一部分而已，我要怎么做，让它自动分页呢？
还有怎样把它改成打印预览的模式显示出来再打印呢？
英文不太好，找了很旧帮助也没找到方法，希望高手指点！

先计算某一页最多能打印的图片高度，然后将图片分页

问题是代码要怎么写？