QWebEnginePage: toHtml returns an empty string - c++

Question

I need to retrieve some html from a QWebEnginePage. I found in the documentation the method toHtml but it always returns an empty string. I tried toPlainText
and it works, but this is not what I need.
MyClass::MyClass(QObject *parent) : QObject(parent)
{
_wp = new QWebEnginePage();
_wp->settings()->setAttribute(QWebEngineSettings::AutoLoadImages, false);
_wp->settings()->setAttribute(QWebEngineSettings::JavascriptEnabled, true);
connect(_wp, SIGNAL(loadFinished(bool)), this, SLOT(wpLoadFinished(bool)));
}
void MyClass::start()
{
_wp->load(QUrl("http://google.com/"));
}
void MyClass::wpLoadFinished(bool s)
{
_wp->toHtml(
[] (const QString &result) {
qDebug()<<"html:";
qDebug()<<result;
}); // return empty string
/*_wp->toPlainText(
[] (const QString &result) {
qDebug()<<"txt:";
qDebug()<<result;
});*/ //works perfectly
}
What am I doing wrong?

Answer 1

I am getting my head around QWebEngine. It is very cool. I have got the following to work.
The lambada capture needs to be all that is "=", or "this" in the case of signal being emitted. You would also need "mutable" to modify the captured copies. toHtml() is however asynchronous so even if you capture the html it is unlikely it would be available directly after the call to toHtml() in SomeFunction. You can overcome this by using a signal and slot.
protected slots:
void handleHtml(QString sHtml);
signals:
void html(QString sHtml);
void MainWindow::SomeFunction()
{
connect(this, SIGNAL(html(QString)), this, SLOT(handleHtml(QString)));
view->page()->toHtml([this](const QString& result) mutable {emit html(result);});
}
void MainWindow::handleHtml(QString sHtml)
{
qDebug()<<"myhtml"<< sHtml;
}

Answer 2

I think that the problem is more a connection problem. Your code works fine on my appli :
connect(page, SIGNAL(loadFinished(bool)), this, SLOT(pageLoadFinished(bool)));
...
page->load(QUrl("http://google.com/"));
...loading time...
void MaClasse :: pageLoadFinished(bool s){
page->toHtml([this](const QString &result){
qDebug()<<"html:";
qDebug()<<result;
item->setHtml(result);});
}