QPrinter causes SIGPIPE error

PhTe

I have a Qml application with Qt 5.4.1 and try to convert a HTML page to a PDF file.
When i start my app and call the function to convert shortly after the startup it works all fine.
But when i wait a few minutes after startup (My app does nothing else in this time, just showing the Qml ui) and then call the function, the QPrinter constructor causes a SIGPIPE - Broken Pipe error.

Does anyone knows why? And how to prevent this?

bool PdfExport::exportFile(const char *path) {

    QWebPage page;
    page.mainFrame()->setContent(exportString().c_str());
    printf("create printer\n");
    fflush(stdout);
    QPrinter *printer = new QPrinter(QPrinter::HighResolution); // Causes SIGPIPE error!!

    printf("set printer properties\n");
    fflush(stdout);
    printer->setPageMargins(5, 5, 5, 5, QPrinter::Millimeter);
    printer->setCreator(QString(this->creator.c_str()));
    printer->setDocName(QString(this->docName.c_str()));
    printer->setPageSize(QPrinter::A4);
    printer->setPrintRange(QPrinter::AllPages);

    printf("set output path\n");
    fflush(stdout);
    printer->setOutputFileName(path);

    printf("print\n");
    fflush(stdout);
    page.mainFrame()->print(printer);

    printf("delete printer\n");
    fflush(stdout);

    delete printer;

    printf("finish\n");
    fflush(stdout);

    return true;
}

I have already added

void handler(int s) {
    printf("Caught SIGPIPE %d\n", s);
    fflush(stdout);
}

int main(int argc, char *argv[]) {

    signal(SIGPIPE, handler);

    struct sigaction sa;
    sa.sa_handler = handler;
    sa.sa_flags = 0;
    if (sigaction(SIGPIPE, &sa, 0) == -1) {
      printf("Could not set SIGPIPE handler\n");
    }
    ....

in my main function. but the handler is never called...

jsulm

Why do you create QPrinter on the heap?

One note: you are using printf() C function for debugging. With Qt you can use:

qDebug() << "SOME TEXT";

Or at least std::cout, at the end you are writing C++ code :-)

PhTe

I know i could use qDebug oder cout.

It should not make any difference if i create QPrinter on the heap or as a member variable of my class, does it?

jsulm

It should not make a difference.
You could debug into QPrinter constructor to see where exactly the problem is.

PhTe

I will try to debug in QPrinter, but therefore i have to compile QT in debug mode. It will take a while..