1377269 - [meta] Draw highlighters on platform

Status: RESOLVED WONTFIX

(DevTools :: Inspector, enhancement, P3)

Description

[Matteo Ferretti [:zer0] [:matteo]]

This meta is for the investigation and implementation about how to draw the highlighters on platform code instead of the current approach that uses the Anonymous Content API.

Comment 1

[Matt Woodrow (:mattwoodrow)]

We had a chat about this this week.

It sounds like the big problems are that devtools need to recompute a lot of complex state that is already known to layout, and that devtools overlays don't respond to APZ.

The discussed solution was to add a DOM API that lets devtools request specific (hardcoded) overlays for given elements, and then platform can emit display items to draw the required overlay during normal display list building. This would let the overlay items pick up the same async scrolling metadata as the rest of the content for that element.

They generally want the overlays to be on top of all web content, so we'd probably want to temporarily store an generated items somewhere (on the builder somewhere?) and then append them to the top of the final display list.

They also want to override any clips set by content so that overlays can cover the whole page, but we need to make sure we don't escape the content area and into the UI (for non-e10s). Not entirely sure how that could work, but it seems feasible.

What do you think Markus?

Comment 2

[Patrick Brosset <:pbro>]

Clearing the needinfo on this old technical refactoring idea.
I would like to keep the bug open still. We still have a lot of complex code around positioning highlighters, and a lot of bugs. But the investment to change this is large and I don't think we want to attempt this now.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The meta keyword is there, the bug doesn't depend on other bugs and there is no activity for 12 months.
:rcaliman, maybe it's time to close this bug?

Comment 4

[Razvan Caliman [:rcaliman]]

We won't be investing in this approach in the near term. Makes sense to close this bug now and reopen it later if required.