On Thu, Feb 27, 2020 at 12:17 PM Yoav Weiss <y...@yoav.ws> wrote: > > > On Wed, Feb 26, 2020 at 11:33 PM Ryosuke Niwa <rn...@webkit.org> wrote: > >> >> I don't think we should do that. For starters, Chrome's painting strategy >> while loading a web page is very different from that of Safari / WebKit. We >> would freeze the painting of the previous page at the moment a new >> navigation is committed, and we wouldn't update the painting until the >> destination page has a meaningful content in it. This is a very much >> different from Chrome's model where the moment a new navigation is >> committed, Chrome will show a blank page then start incrementally painting >> the page throughout the navigation. >> > Body background color is still painted before any contentful paint... Is this a bug? Also, a web page might not have content at all (e.g. a bunch of divs with bgcolors). Would webkit not render that web page at all?
> >> Second off, the point of specification is to allow multiple independent >> implementations. If we had to reverse-engineer what Chrome is doing and >> implement that, it defeats the point of having any standard at all. >> > > With my WebPerfWG hat on, I agree. Would be good to find a model that > works well for different implementations (even if not comparable between > different implementations), while providing points in time for developers > that can: a) provide a user meaningful visual metric and b) enable spotting > regressions. > Note taken. Though this is hypothetical - let's get to the point where the spec is lacking, and then we can decide how to go about it. What I propose is to go as far as possible with the spec, and when we reach an ambiguity tackle it on the spec front. > > Would WebKit folks be interested in helping exploration on that front? > I would be happy to help coordinate this (e.g. work on the details of pec differences and prod Ryosuke and folks for feedback about internals). > >> I don't think we don't should that because we don't have an equivalent of >> first-paint. >> > > FWIW, I don't think it's a huge problem if WebKit will report FP and FCP > as the same timestamp, as they are indeed the same point in time. > A simple test shows that safari does show the background color (body=bgcolor) when a timeout is set to render everything else (e.g. add text to the document). According to the spec, the first one should give first-paint and the second one would be first-contentful-paint.
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