Printer problem

[K4ELO]

Running Qt under Windows and for some reason it can't find the printers (there are 7 including both network and usb printers).

Here's the relevant code:

QT += sql \
    printsupport \
    serialport \
    xml \
    network \
     widgets
 
 
from mainwindow.h
#include <QPrinter>
#include <QPrintDialog>
#include <QPrinterInfo>
 
from mainwindow.cpp
QList <QPrinterInfo> plist = QPrinterInfo::availablePrinters();
  qDebug() << "len = " << plist.length(); // len comes back zero
 
  QPrinter printer;
  printer.setPrinterName("DYMO LabelWriter 450");
  qDebug() << "printer valid? " << printer.isValid(); // comes back false

QT += sql \
    printsupport \
    serialport \
    xml \
    network \
     widgets


from mainwindow.h
#include <QPrinter>
#include <QPrintDialog>
#include <QPrinterInfo>

from mainwindow.cpp
QList <QPrinterInfo> plist = QPrinterInfo::availablePrinters();
  qDebug() << "len = " << plist.length(); // len comes back zero

  QPrinter printer;
  printer.setPrinterName("DYMO LabelWriter 450");
  qDebug() << "printer valid? " << printer.isValid(); // comes back false

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I have another application that uses the same code and it reports 7 printers and prints to the Dymo just fine.
Any idea what I am missing here?

[derrickbj]

What happens if you use a PrintDialog instead? Something like

QPrintDialog dialog(printer, this);
 if (dialog.exec() == QDialog::Rejected) {
        return;
    }

QPrintDialog dialog(printer, this);
 if (dialog.exec() == QDialog::Rejected) {
        return;
    }

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Does it show a list of printers attached to the computer?

[K4ELO]

QPrintDialog returns: QPrintDialog: Cannot be used on non-native printers
Because no printers are found.

[yagabey]

I also have the same problem. On my development machine(Win7 64 Bit, Qt 5.2 mingw) it works. But when i deploy the application to another computer i get the warning:

QPrintDialog: Cannot be used on non-native printers

I tried it with WinXP on virtualbox, again the problem exists. plugins\printsupport\windowsprintersupport.dll and platform\qwindows.dll exists in binary folder.

Any idea ?

[K4ELO]

Sorry Yagabey, no idea. Also running under Win 7/64. I have 2 applications. Both use the same code. It works on one but not the other. The one that does not work returns a list of zero printers from QList <QPrinterInfo> plist = QPrinterInfo::availablePrinters();
And print dialog gives me the same error message that you get.

[Ritchie]

Hi guys! I had the same problem and the reason was I put the wrong "windowsprintersupport.dll" in "plugins\printsupport\" dir. There were two different dll files in my Qt dir. You should take the right one.

[hazad]

QPrintDialog can't be used with pdfs on Windows because it is a native print dialog and has no knowledge of Qt's PDF printer.

[psb2519]

I have the same problem...
I changed the line
printer.setOutputFileName("Filename.pdf");
to
printer.setOutputFileName("Filename");
and the printdialog worked.
I made sure the print to file was not ticked...and whalla...(ozzie slang for great it worked)
a print of what I wanted worked.

Thanks for the Help to all