QPrinter issues

MrShawn

Hey guys,

So I am having a strange issue where QPrinter works fine in one qt project and doesn't in the other. I am using Qt 5.10 ( I am tempted to say it is NOT the version but it could be).

I made a simple project which basically runs this chunk of code just fine.

    QPrinter myPrinter;
    if (myPrinter.isValid())
    {
        qDebug() << myPrinter.printerName();
        QTextDocument doc("Test page!\nAnother Line!");
        doc.print(&myPrinter);
    }
    qDebug() << QPrinterInfo::availablePrinterNames();

It prints a few lines to the default printer. Later I print out all available printers to check some things and look at what APrinterInfo has to offer. That is basically all it does it is a blank application project where i run this in main window constructor.

My other project essentially runs the same code but cannot seem to not find my printers and I am not sure why. The printer name is blank. The available printer list empty. No default printer exists either. I have the printsupport added to the .pro file in both projects, if I didn't simply adding the printer includes would not work. It is also the same machine so it should see the same printers.

I will be actively working to resolve this issue but if there are any pointers/ideas I would greatly appreciate it.

Thanks,
Shawn

SGaist

Hi,

Let's start by a maybe silly question: are you using the same kit to build both applications ?
Are you starting both from Qt Creator ?

MrShawn

Yes, and yes.

SGaist

Then I'd check for differences in the environment variables in the build and the run parts of the Project panel.

MrShawn

Everything looks to be the same beside the specific differences in the .pro files names

MrShawn

Do I need to free the printer resource? For example if I open a serial port that resource is in use to another program unless you close it first. I see no QPrinter.close() or something like that so I assume that is not case.

SGaist

Do you mean it happens if you run both application at the same time ?

What OS are you running ?

MrShawn

I run them at different times. What I mean is that I can open the serial resource in a test program (and fail to close it when the program ends) and any other call to open the serial resource will claim its in use until the resource is closed. I am wondering if this behaves in a similar manner.

I made the small one to test how to print things, then I basically added the code to my other project after I figured it out. In my test project it worked fine. Now in my other project it doesn't work. I can run the test one at any time and it works.

Windows 7 pro

SGaist

How are you handling the printing in your big project ? What is different than from your small project ?

MrShawn

Honestly the only difference is that I generate the string for the QTextDocument constructor, which should have no effect on setting up my QPrinter and seeing printers (to my knowledge).

MrShawn

The good news is I got it working!

@SGaist not sure if you have insight as to why but I did do clean, ran qmake, and build several times. In the end I changed the build directory to be totally fresh. When I did that and rebuilt into the new directory it worked just fine.

@SGaist Thanks a lot for helping, I appreciate it!