[webkit-dev] Lazy loading

Rob Buis rbuis at igalia.com
Mon Oct 28 11:39:59 PDT 2019


I made a lazy image loading prototype earlier this year 
(https://bugs.webkit.org/show_bug.cgi?id=196698) and have been splitting 
it up into reviewable patches. The main implementation part landed 
recently so I am wondering about the next steps.

One thing left to do for sure is cleaning up/adding tests. For one there 
are tests in http/tests/lazyload which can just be WPT tests, so I'll 
work in this area for sure. As usual, while adding new tests bugs may 
show up and more patches will be needed.

Another possible task is implementing metadata fetch, but it makes the 
code more complex and chromium has backtracked from it.

Changing the behavior of loading=auto to make lazy loading the default 
seems risky and should possibly only be done when lazy image loading is 
deemed stable enough.

Yet another possible task is making lazy loading work for CSS 
backgrounds, this is implemented in the prototype but I don't think 
there are many tests for it.

A related task is implementing lazy loading for iframe's, I took a quick 
look and this looks like similar work to lazy image loading, but should 
be much easier to implement now the building blocks are there.

Finally there is the task of setting threshold viewport distance values 
for triggering deferred loads. I only have access to iOS simulator, so I 
wonder if that is something Apple could help with?

I do not have a strong preference among these tasks. Thoughts?


P.S: I intend to attend the WebKit Contributors meeting, so feel free to 
chat with me there about lazy loading.

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