QPrinter printer;

  QPrintDialog dialog(&printer, this);
  dialog.setWindowTitle(tr("Print Document"));
  if (dialog.exec() != QDialog::Accepted) {
    return;
  }


  QPainter painter;

  bool success = painter.begin(&printer);
  Q_ASSERT(success);

  double xscale = printer.pageRect().width()/double(ui->tableViewAnleitung->width());
  double yscale = printer.pageRect().height()/double(ui->tableViewAnleitung->height());
  double scale = qMin(xscale, yscale);
  painter.translate(printer.paperRect().x() + printer.pageRect().width()/2,
                    printer.paperRect().y() + printer.pageRect().height()/2);
  painter.scale(scale, scale);
  painter.translate(-width()/2, -height()/2);

  ui->tableViewAnleitung->render(&painter);
  painter.end()

QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::setRenderHint: Painter must be active to set rendering hints
QPainter::setWorldTransform: Painter not active
QWidget::render: Cannot render with an inactive painter

        // Create a pixmap device coordinate painter.
        QPainter pixmapPainter(&pixmap);
        pixmapPainter.setRenderHints(painter->renderHints());
        transform *= QTransform::fromTranslate(-deviceRect.x(), -deviceRect.y());
        pixmapPainter.setTransform(transform);