Bug 38921

In QWebFrame docs we have: (..) /*! \fn void QWebFrame::initialLayoutCompleted() This signal is emitted when the frame is laid out the first time. This is the first time you will see contents displayed on the frame. \note A frame can be laid out multiple times. */ (..) However FrameLoaderClient::dispatchDidFirstLayout (who emits initialLayoutCompleted) can be called more than once and even when there is no content in fact "drawn". One example of this is when ones changes the viewport size (QWebPage::setViewportSize) before any page load, as in following snippet: void tst_QGraphicsWebView::crashOnViewlessWebPages() { QGraphicsScene scene; QGraphicsView view(&scene); QGraphicsWebView* webView = new QGraphicsWebView; WebPage* page = new WebPage; webView->setPage(page); page->webView = webView; scene.addItem(webView); connect(page->mainFrame(), SIGNAL(initialLayoutCompleted()), page, SLOT(aborting())); view.setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding); view.resize(600, 480); webView->resize(view.geometry().size()); QCoreApplication::processEvents(); view.show(); page->mainFrame()->setHtml(QString("data:text/html,<h1>blah")); (...) } "initialLayoutCompleted" signal is emitted (and WebPage::aborting slot is called) even before page->mainFrame()->setHtml is executed because there is a webView->resize (which triggers qwebpage::setViewportSize and FrameView::layout()) In r39385 FrameLoaderClient::dispatchDidFirstVisuallyNonEmptyLayout was introduced, and I think it is the best place to emit initialLayoutCompleted signal. Its documentation says: "Add new FrameLoaderClient method to indicate the first visually non-empty layout based on an heuristic. Right now that heuristic is the first layout after an image, text or plugin has been added to the render tree, but I can imagine it becoming much smarter." and it matches more to qwebframe docs.