Created attachment 384772 [details] qq page loading transition When I visit qq.com, I see a flash of white before the actual content fills in. See the 3 second mark in the attached video, which I took on a recent trunk release build of Safari. This may be because we complete the page transition (which unfreezes the layer tree) on the first layout rather than the first visually-non-empty layout. There's a comment about this in WebFrameLoaderClient::dispatchDidReachLayoutMilestone: if (milestones & DidFirstLayout) { // ... #if PLATFORM(MAC) // FIXME: Do this on DidFirstVisuallyNonEmptyLayout when Mac Safari is able to handle it (<rdar://problem/17580021>) if (m_frame->isMainFrame() && !m_didCompletePageTransition && !webPage->corePage()->settings().suppressesIncrementalRendering()) { RELEASE_LOG(Layout, "%p - WebFrameLoaderClient::dispatchDidReachLayoutMilestone: dispatching didCompletePageTransition, page = %p", this, webPage); webPage->didCompletePageTransition(); m_didCompletePageTransition = true; } #endif
<rdar://problem/57609711>
I noticed that this happens when navigating to qq.com via the location field, but *not* when clicking a link to qq.com, or navigating there via JavaScript in a page. Perhaps the white flash is an artifact of WebView swapping (which Safari does for location field navigation and favorites, but not for in-page links)? I think other pages white-flash too, possibly for similar reasons.
This particular flash of white looks more like a Safari-specific issue in the way navbar loads are handled, which we are tracking in <rdar://problem/58936254>. There is another issue in WebKit that can cause certain websites (but not QQ) to flash white when an early layout occurs, which we're tracking in https://bugs.webkit.org/show_bug.cgi?id=207516. *** This bug has been marked as a duplicate of bug 207516 ***