how to get the real width and hight of the web pages what have loaded?

[nicker player]

//m_WidgetBrowser means the widget of the webengineview
connect(m_WidgetBrowser->page(), &QWebEnginePage::loadFinished, [this](bool ok) {
            if (ok) {
                m_WidgetBrowser->page()->runJavaScript("document.body.scrollWidth", [this](const QVariant &widthResult) {
                    int pageWidth = widthResult.toInt();
                    int viewWidth = m_WidgetBrowser->width();
                    double zoomFactorWidth = static_cast<double>(viewWidth) / static_cast<double>(pageWidth);
                    m_WidgetBrowser->page()->runJavaScript("document.body.scrollHeight;", [this,pageWidth](const QVariant &heightResult) {
                        int pageHeight = heightResult.toInt();
                        int viewHeight = this->m_WidgetBrowser->height();
                        emit onSignalResize(pageWidth,pageHeight);
                        //the signal is to reszie the widget of the webegine m_WidgetBrowser->resize(pageWidth,pageHeight);

                    });
                });
            }
        });
    }

I tested the code above.but on some platforms it worked.some dosent.
Is there any way to get the real width and height of the pages which loadfinished?

[nicker player]

and if I set the source file whit the setHtml() function.
it is hard to get the real height and width if the source was made by the txt.