This application generates a test pdf file using QPrinter and QPainter. The call to QPainter::begin() opens a dialog used to enter the PDF file name and location:

Qt Code: 
  1. #include <iostream>
  2. #include <QApplication>
  3. #include <QPrinterInfo>
  4. #include <QPainter>
  5.  
  6. int main(int argc, char *argv[])
  7. {
  8.     QApplication app(argc, argv);
  9.  
  10.     foreach(QPrinterInfo printerInfo, QPrinterInfo::availablePrinters()) {
  11.         if (printerInfo.state() == QPrinter::PrinterState::Error)
  12.             continue;
  13.  
  14.         // Look for the virtual printer device that generates a pdf.
  15.         if (printerInfo.printerName() == "Microsoft Print to PDF")
  16.         {
  17.             QPrinter * qPrinter = new QPrinter(printerInfo, QPrinter::HighResolution);
  18.             QPainter * qPainter = new QPainter();
  19.  
  20.             // This statement pops up a file selection dialog.
  21.             // When it is cancelled, the application crashes ...
  22.             qPainter->begin(qPrinter);
  23.  
  24.             // ... and this statement is never reached.
  25.             std::cout << "Starting printing on the pdf file." << std::endl;
  26.  
  27.             // We print some text in the PDF file.
  28.             qPainter->drawText(100, 100, "Lorem ipsum dolor sit amet, consectetur adipiscing elit.");
  29.             qPrinter->newPage();
  30.             qPainter->drawText(100, 100, "Mauris ut urna eget dui eleifend placerat.");
  31.             qPrinter->newPage();
  32.  
  33.             // Close the printer and clean-up.
  34.             qPainter->end();
  35.             delete qPrinter;
  36.             delete qPainter;
  37.         }
  38.     }
  39.  
  40.     return 0;
  41. }
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It works correctly when a PDF file name is introduced in the dialog. However, by clicking on the Cancel button the application crashes during the call to QPainter::begin().

Is there a way to prevent this crash? Is the previous code correct, or is there something missing?

Thanks in advance and best regards.