How to print from QWebEngineView

Question

I am trying to print a report from within my application, which involves both text and tables. Since QTextDocument won\'t be sufficient, I\'ve decided to go with

Answer 1

In the first approach I think it fails because the HTML or url is not loaded yet and you want to print the text, so a possible solution is to use the loadFinished signal to start printing and use pdfPrintingFinished to know when the printing is finished.

#include 

class Widget : public QWidget
{
public:
    explicit Widget(QWidget *parent = nullptr):
        QWidget(parent), button(new QPushButton), progressbar(new QProgressBar), view(new QWebEngineView)
    {
        button->setText(tr("Press me"));
        button->setEnabled(false);

        connect(button, &QPushButton::clicked, this, &Widget::onClicked);
        connect(view, &QWebEngineView::loadFinished, this, &Widget::onLoadFinished);
        connect(view->page(), &QWebEnginePage::pdfPrintingFinished, this, &Widget::onPdfPrintingFinished);

        QString html = R"(
                       
                       
                       
                       
                       

                       
HTML Table

                       

                       

                       
Company
                       
Contact
                       
Country
                       
                       

                       
Alfreds Futterkiste
                       
Maria Anders
                       
Germany
                       
                       

                       
Centro comercial Moctezuma
                       
Francisco Chang
                       
Mexico
                       
                       

                       
Ernst Handel
                       
Roland Mendel
                       
Austria
                       
                       

                       
Island Trading
                       
Helen Bennett
                       
UK
                       
                       

                       
Laughing Bacchus Winecellars
                       
Yoshi Tannamuri
                       
Canada
                       
                       

                       
Magazzini Alimentari Riuniti
                       
Giovanni Rovelli
                       
Italy
                       
                       

                       
                       
                       )";

        view->setHtml(html);
        auto lay = new QVBoxLayout(this);
        lay->addWidget(button);
        lay->addWidget(progressbar);
        lay->addWidget(view);
        resize(640, 480);
    }
private:
    void onLoadFinished(bool ok){
        button->setEnabled(ok);
    }
    void onClicked(){
        progressbar->setRange(0, 0);
        QString fn = "/Users/s710/Downloads/test.pdf";
        view->page()->printToPdf(fn);
    }
    void onPdfPrintingFinished(const QString & filename, bool ok){
        qDebug() << filename << ok;
        progressbar->setRange(0, 1);
    }
private:
    QPushButton *button;
    QProgressBar *progressbar;
    QWebEngineView *view;
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}

In the case where you use QPrinter I think that the error is caused because QPrinter is a local variable that is eliminated when the function is finished executing but Qt tries to access that variable asynchronously but the object does not exist. The solution is to extend the scope of QPrinter.

#include 

class Widget : public QWidget
{
public:
    Widget(QWidget *parent = nullptr):
        QWidget(parent), button(new QPushButton), progressbar(new QProgressBar), view(new QWebEngineView)
    {
        button->setText(tr("Press me"));
        button->setEnabled(false);

        connect(button, &QPushButton::clicked, this, &Widget::onClicked);
        connect(view, &QWebEngineView::loadFinished, this, &Widget::onLoadFinished);

        printer.setResolution(QPrinter::PrinterResolution);
        printer.setOutputFormat(QPrinter::NativeFormat);
        printer.setPaperSize(QPrinter::A4);
        printer.setPageMargins(12, 16, 12, 20, QPrinter::Millimeter);
        QString html = R"(
                       
                       
                       
                       
                       

                       
HTML Table

                       

                       

                       
Company
                       
Contact
                       
Country
                       
                       

                       
Alfreds Futterkiste
                       
Maria Anders
                       
Germany
                       
                       

                       
Centro comercial Moctezuma
                       
Francisco Chang
                       
Mexico
                       
                       

                       
Ernst Handel
                       
Roland Mendel
                       
Austria
                       
                       

                       
Island Trading
                       
Helen Bennett
                       
UK
                       
                       

                       
Laughing Bacchus Winecellars
                       
Yoshi Tannamuri
                       
Canada
                       
                       

                       
Magazzini Alimentari Riuniti
                       
Giovanni Rovelli
                       
Italy
                       
                       

                       
                       
                       )";

        view->setHtml(html);

        auto lay = new QVBoxLayout(this);
        lay->addWidget(button);
        lay->addWidget(progressbar);
        lay->addWidget(view);
        resize(640, 480);
    }
private:
    void onLoadFinished(bool ok){
        button->setEnabled(ok);
    }
    void onClicked(){
        progressbar->setRange(0, 0);
        QString fn = "/Users/s710/Downloads/test.pdf";
        printer.setOutputFileName(fn);
        view->page()->print(&printer, [this](bool ok){
            qDebug() << ok;
            progressbar->setRange(0, 1);
        });
    }
private:
    QPushButton *button;
    QProgressBar *progressbar;
    QWebEngineView *view;
    QPrinter printer;
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}