I am using Qt version 4.8.4 on Window 7. I don’t have conditions to test this issue on another platform such as Mac, Linux… and I use the following code to preview content

Qt Code: 
  1. void DemoClass::on_btnOK_clicked()
  2. {
  3.     QPrinter printer;
  4.     printer.setResolution(QPrinter::HighResolution);
  5.     printer.setPaperSize(QPrinter::A4);
  6.     printer.setOrientation(QPrinter::Portrait);
  7.     printer.setFullPage(true);
  8.  
  9.     QPrintPreviewDialog *printPreview = new QPrintPreviewDialog(&printer);
  10.     connect(printPreview, SIGNAL(paintRequested(QPrinter*)), this, SLOT(print(QPrinter*)));
  11.  
  12.     printPreview->setWindowTitle("Preview Dialog");
  13.     Qt::WindowFlags flags(Qt::WindowTitleHint);
  14.     printPreview->setWindowFlags(flags);
  15.     printPreview->exec();
  16. }
  17.  
  18. void DemoClass::print(QPrinter *printer)
  19. {
  20.     QPainter painter(printer);
  21.     painter.setRenderHints(QPainter::Antialiasing |
  22.                            QPainter::TextAntialiasing |
  23.                            QPainter::SmoothPixmapTransform, true);
  24.  
  25.     painter.drawText(100, 100, "Hello World! 123");
  26. }
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On pushing the OK button, this dialog appears:

09-09-2013 18-03-43.png

As you see, the page is blank. The page doesn’t contain any content. Then I click the page setup button on the preview dialog and this appears:

09-09-2013 18-04-23.png

…without changing anything, I click OK and then the preview becomes correct:

09-09-2013 18-05-18.png

I really don’t understand what the reason is. How can I show the content correctly without changing page setup?

Do you have any solutions?