Application crahes on QWebEnginePage printing attempt

abduunn

Hello everyone

I am trying to use the print method of QWebEnginePage with the following code. The application crashes and I can't see where the problem is:

    QPrinter printer;
    QPrintDialog *pDlg = new QPrintDialog(&printer, this);
    QWebEngineView *view = new QWebEngineView(this);
    view->setHtml("<h1>Hello</h1>", QUrl("about:blank"));

    if (pDlg->exec()) {
        view->page()->print(&printer, [=](bool) {});
    }

I tried to run it under debugging and it seems to crash on QWin32PrintEngine.
I also tried to use the printToPdf method and it exports a pdf file just fine.

The same method is used to print a QTextEdit widget contents using the same printer:

        QPrinter printer;
        QPrintDialog *pDlg = new QPrintDialog(&printer, this);
        QTextEdit *tedit = new QTextEdit("Hello");
        if (pDlg->exec()) {
            tedit->print(&printer);
        }

What am I doing wrong?
Thank you all in advance.

SGaist

Hi and welcome to devnet,

You are not checking that the call to page returns a valid pointer.

abduunn

@SGaist said in Application crahes on QWebEnginePage printing attempt:

checking that the call to page returns a valid pointer.

Thank you.

With the clue I had from this response, and with the help of demobrowser example which is bundled with Qt-5.6 I rewrote the code and could send the page to printer successfully.

the code after the modification:

        QWebEngineView *view = new QWebEngineView(this);
        view->setHtml("<h1>Hello</h1>", QUrl("about:blank"));
        printRequest(view->page());

the functions are defined as following


void MainWindow::slotHandlePagePrinted(bool result)
{
    Q_UNUSED(result);

    delete printer;
    printer = nullptr;
}

void MainWindow::printRequest(QWebEnginePage *page)
{
    if (printer)
        return;
    printer = new QPrinter();
    QScopedPointer<QPrintDialog> dialog(new QPrintDialog(printer, this));
    if (dialog->exec() != QDialog::Accepted) {
        slotHandlePagePrinted(true);
        return;
    }
    else {
        page->print(printer, [=](bool) {});
    }
}

and in the header file:

private slots:
    void slotHandlePagePrinted(bool result);

private:
    QPrinter *printer;
    void printRequest(QWebEnginePage *page);