[Webkit-unassigned] [Bug 164180] [GTK] No way to safely use webkit_web_view_get_snapshot() as pages are not rendered when LOAD_FINISHED is called

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=164180

--- Comment #6 from Carlos Garcia Campos <cgarcia at igalia.com> ---
(In reply to comment #4)
> (In reply to comment #3)
> > (In reply to comment #2)
> > > (In reply to comment #1)
> > > > I don't think we should change the semantics of LOAD_FINISHED, we should
> > > > probably expose APILoaderClient::didReachLayoutMilestone, and the
> > > > applications could wait for DidFirstVisuallyNonEmptyLayout or
> > > > DidHitRelevantRepaintedObjectsAreaThreshold, I don't know the details of the
> > > > milestones.
> > > 
> > > Why you think we should not change when LOAD_FINISHED triggers?
> > > What is the use case of having a LOAD_FINISHED signal that doesn't trigger
> > > always when the page is fully rendered??
> > 
> > Because load finished is not about rendering but about networking, the page
> > finished loading, but not necessarily rendering. That's why there are other
> > callbacks more related to rendering like the ones I mentioned before.
> 
> I think that this is an internal implementation detail that don't
> necessarily has to be exposed in our API
> 
> Quoting our docs:
> 
> " WEBKIT_LOAD_FINISHED This state means that everything that was required to
> display the page has been loaded. "

Everything required to display doesn't mean it has displayed eferything, only that the resources are there, but you have to parse, layout, paint, etc.

> https://webkitgtk.org/reference/webkitgtk/stable/WebKitWebFrame.
> html#WebKitLoadStatus
> 
> And after reading that twice, I would expect that when LOAD_FINISHED
> triggers the page is always fully rendered.
> 
> Adding a new state is an option, but I think is a bad idea to do it, if we
> only add it for the sake of exposing the internal implementation.
> 
> So, what is the use case for an application to have both
> WEBKIT_LOAD_FINISHED and WEBKIT_LOAD_FINISHED_AND_RENDERED_COMPLETED ?

I don't think it's possible to know when a page has finished rendering, you can know if something has rendered, or if there was a layout, etc. But, if page has dynamic contents or animations. Load events has to do with the load, what happens in WebCore/loader, not with the layout or render. If we want to expose notifications about those I would not add new load events, but a different signal or whatever

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