1528257 - [meta] Faster animations in WebRender and display list format

Status: RESOLVED INVALID

(Core :: Graphics: WebRender, enhancement, P3)

Description

[Nicolas Silva [:nical]]

Animations that cause us to rebuild the display list tend to use a Lot of CPU as we have to re-build the display list, the scene, the frame and then render. We also do all of this work when the thing that changed is off-screen.

By "animations" I'll only refer to the ones that don't affect the structure of the display list. For the remaining animations we could chose to discuss the ones that are simple drawing parameters such as colors and the ones that affect positions/sizes separately if need be.

Ideally we would be able to avoid:

• when the animation is visible: display list building and scene building
• when the animation is no visible: everything between display list building and rendering.

Without going that far a good initial target could be to avoid the rather high cost of scene building for common types of animations.

There have been a number of discussions about various approaches to improve in this area but I haven't come across any of it in written form.

I remember two approaches being mentioned at the last allhands:

• (A) Add more animated properties to webrender and other ways to skip scene building.
• (B) Make scene building much cheaper one way or another. For example through incremental display list updates or some other means. I also vaguely remember mentions of changing the format of the display list altogether, taking advantage of some of gecko's data structures that resemble what webrender re-constructs internally. I don't know if/how it would interact.

It'd be great to get general idea of the direction we want to go towards to avoid wasted work.

Comment 1

[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.
:jbonisteel, maybe it's time to close this bug?

Comment 2

[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.
:jimm, maybe it's time to close this bug?