On Thu, Feb 27, 2020 at 11:47 AM Noam Rosenthal <n...@webkit.org> wrote:
> > > 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). > That sounds great, thank you! :) > > >> >>> 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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