Qt WebEngineView render empty image

Question

I am using qt 5.6.2. I would like to take a screenshot on a web page. Here is the code I am using:

#include <QtWidgets/QApplication>
#include <QtWebEngineWidgets/QWebEngineView>

int main(int argc, char *argv[]){
    int left, top, width, height;
    left = 0;
    top = 0;
    width = 600;
    height = 800;

    QApplication a(argc, argv);
    QWebEngineView* w = new QWebEngineView();
    QImage image(height, width, QImage::Format_RGB32);
    QRegion rg(left, top, width, height);
    QPainter painter(&image);
    w->page()->load(QUrl("https://www.yahoo.com"));
    w->show();
    w->page()->view()->render(&painter, QPoint(), rg);
    painter.end();
    image.save("test.png", "PNG", 80);

    return a.exec();
}

I run the program, a window shows up, I can see the content of yahoo. I then save the result to test.png but that is a white picture. Is it I cannot save the result to image or I cannot save the result from image to file test.pngand how to fix it?

Answer 1

You need to wait for the page to finish loading.

QWebEngineView* w = new QWebEngineView();
w->page()->load(QUrl("https://www.yahoo.com"));
w->show();


QObject::connect(w, &QWebEngineView::loadFinished,
                 [w](bool bOk)
{
    int left, top, width, height;
    left = 0;
    top = 0;
    width = 600;
    height = 800;

    QImage image(height, width, QImage::Format_RGB32);
    QRegion rg(left, top, width, height);
    QPainter painter(&image);
    w->page()->view()->render(&painter, QPoint(), rg);
    painter.end();
    image.save("test.png", "PNG", 80);
});