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[SOLVED] QWebPage / QPrinter - can't load page

  • Hello every body,

    I am new in Qt and I need to do a program who export html page to PDF

    So, the main idea is use QWebPage for interpret html and export itself to pdf with QPrinter.

    I have two class webview who use QWebPage and Print who use QPrinter.

    In main.cpp I have connect LoadFinished to PrintPDF slot:

    @ Print *pdf = new Print(args);
    webview *nav = new webview();

    if(nav->load(args) == false) {
        qDebug() << "can't load page";
        return 0;
    //when the page page is ready, we will print it
    QObject::connect(nav->getFrame(), SIGNAL(loadFinished(bool)), nav, SLOT(printPDF(bool)));

    My webview.cpp class:

    @#include "webview.h"
        page = new QWebPage;
        printer = 0;
        delete page;
    bool webview::load(Arguments *args)
        QRegularExpression url("^(file|http)://");
        QRegularExpression fullPath("^/");
        QRegularExpressionMatch pathMatch = fullPath.match(args->getSource());
        QRegularExpressionMatch urlMatch = url.match(args->getSource());
        // see http://qt-project.org/doc/qt-4.8/qwebsettings.html#WebAttribute-enum for more informations
        page->settings()->setAttribute(QWebSettings::LocalStorageEnabled, true);
        page->settings()->setAttribute(QWebSettings::AutoLoadImages, true);
        page->settings()->setAttribute(QWebSettings::JavascriptEnabled, true);
        page->settings()->setAttribute(QWebSettings::PrintElementBackgrounds, true);
        page->settings()->setAttribute(QWebSettings::PluginsEnabled, true);
        if(pathMatch.hasMatch()) {
        } else {
            if (urlMatch.hasMatch()) {
            } else {
                fprintf(stderr, "%s\n", qPrintable(QApplication::translate("main", "Error: Invalide source file")));
                return false;
        return true;
    void webview::printPDF(bool ok)
        if(ok == true) {
            qDebug() << "okay";
        } else
            qDebug() << "non okay";
        if(printer != 0)


    This is what my console display:

    bq. non okay
    QPainter::begin: A paint device can only be painted by one painter at a time.

    I noticed with a Local Printer in the printPDF Method it works (but the page has been printed is a blank page)

    I have no idea where the error might be due. The whole project is here : http://paf.im/9zSsL

    The arguments are:

    @ ./htmltopdf http://qt-project.org destinationFolder@

    (destinationFolder is not yet implemented, you must directly modify the source code)

  • The problem was elsewhere :

    In my main.cpp I had this :

    @QObject::connect(nav->getFrame(), SIGNAL(loadFinished(bool)), nav, SLOT(printPDF(bool)));
    delete args;
    delete pdf;
    delete nav;

    return app.exec();@

    app.exec() is a kind of infinit loop who thaht handles Qt events and thus allows the program does not close. If I proceed to delete before calling this function,then I will have freshly deallocated pointers that will be used

    If I Do :

    @bool result = app.exec();

    delete args;
    delete pdf;
    delete nav;

    return result;@

    It's work fine !

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