- Qt 6.12
- Qt WebEngine
- Qt WebEngine Widgets Examples
- WebEngine Widgets Html2Pdf Example
- Qt 6.12.0 Reference Documentation

# WebEngine Widgets Html2Pdf Example

Converts web pages to PDF documents using Qt WebEngine.

Html2Pdf demonstrates how to use Qt WebEngine to implement a command-line application for converting web pages into PDF documents.

#### Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, see Qt Creator: Tutorial: Build and run.

#### The Conversion Process

In order to convert a web page into a PDF document we need to:

1. Create a QWebEngineView.
2. Tell the QWebEngineView to begin loading the target URL and wait for it to finish.
3. Tell the QWebEngineView to begin converting the loaded page into a PDF file and again wait for it to finish.
4. Once the conversion is finished, exit the program.

This process is encapsulated in the Html2PdfConverter class:

     #include <QApplication>
     #include <QCommandLineParser>
     #include <QFile>
     #include <QTextStream>
     #include <QWebEngineView>

     #include <functional>
     #include <utility>

     class Html2PdfConverter : public QObject
     {
         Q_OBJECT
     public:
         explicit Html2PdfConverter(QString inputPath, QString outputPath);
         int run();

     private slots:
         void loadFinished(bool ok);
         void pdfPrintingFinished(const QString &filePath, bool success);

     private:
         QString m_inputPath;
         QString m_outputPath;
         QScopedPointer<QWebEngineView> m_view;
     };

In the constructor we create the QWebEngineView and connect to its QWebEngineView::loadFinished and QWebEngineView::pdfPrintingFinished signals:

     Html2PdfConverter::Html2PdfConverter(QString inputPath, QString outputPath)
         : m_inputPath(std::move(inputPath))
         , m_outputPath(std::move(outputPath))
         , m_view(new QWebEngineView)
     {
         connect(m_view.data(), &QWebEngineView::loadFinished,
                 this, &Html2PdfConverter::loadFinished);
         connect(m_view.data(), &QWebEngineView::pdfPrintingFinished,
                 this, &Html2PdfConverter::pdfPrintingFinished);
     }

The `run()` method will trigger the conversion process by asking QWebEnginePage to start loading the target URL. We then enter the main event loop:

     int Html2PdfConverter::run()
     {
         m_view->load(QUrl::fromUserInput(m_inputPath));
         return QApplication::exec();
     }

After the loading is finished we begin PDF generation. We ask the QWebEnginePage::printToPdf method to write the output directly to disk:

     void Html2PdfConverter::loadFinished(bool ok)
     {
         if (!ok) {
             QTextStream(stderr)
                 << tr("failed to load URL '%1'").arg(m_inputPath) << "\n";
             QCoreApplication::exit(1);
             return;
         }

         m_view->printToPdf(m_outputPath);
     }

Once we receive the signal that the PDF conversion has finished, all that remains is to report potential errors and exit the program:

     void Html2PdfConverter::pdfPrintingFinished(const QString &filePath, bool success)
     {
         if (!success) {
             QTextStream(stderr)
                 << tr("failed to print to output file '%1'").arg(filePath) << "\n";
             QCoreApplication::exit(1);
         } else {
             QCoreApplication::quit();
         }
     }

#### The Main Function

Our `main` function is responsible for setting up a QApplication and parsing command line arguments:

     int main(int argc, char *argv[])
     {
         QApplication app(argc, argv);
         QCoreApplication::setOrganizationName("QtExamples");
         QCoreApplication::setApplicationName("html2pdf");
         QCoreApplication::setApplicationVersion(QT_VERSION_STR);

         QCommandLineParser parser;
         parser.setApplicationDescription(
             QCoreApplication::translate("main", "Converts the web page INPUT into the PDF file OUTPUT."));
         parser.addHelpOption();
         parser.addVersionOption();
         parser.addPositionalArgument(
             QCoreApplication::translate("main", "INPUT"),
             QCoreApplication::translate("main", "Input URL for PDF conversion."));
         parser.addPositionalArgument(
             QCoreApplication::translate("main", "OUTPUT"),
             QCoreApplication::translate("main", "Output file name for PDF conversion."));

         parser.process(QCoreApplication::arguments());

         const QStringList requiredArguments = parser.positionalArguments();
         if (requiredArguments.size() != 2)
             parser.showHelp(1);

         Html2PdfConverter converter(requiredArguments.at(0), requiredArguments.at(1));
         return converter.run();
     }

Note that to use Qt WebEngine Widgets we need to create a QApplication and not a QCoreApplication, even though this is a command line application.

Example project @ code.qt.io