1242821 - "Scroll of Lorem Ipsum" demo scrolls poorly

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect, P3)

Description

[Matt Woodrow (:mattwoodrow)]

See URL field for testcase.

This scrolls really smoothly on chrome, but is quite delayed on firefox (with APZ).

The demo is using separate copies of the content for each segment in the ends, and updates the positions of all the copies during an rAF callback to match the scroll position of the primary content.

Comment 1

[Botond Ballo [:botond]]

Attachment: Layer tree

Nice layer tree :)

Matt, does this layer tree look reasonable to you? If not, we should probably address any Layout issues that give rise to this layer tree first.

Comment 2

[Matt Woodrow (:mattwoodrow)]

It's reasonable in the sense that it's what the page is asking for.

The page makes two DOM clones of the scrolled content for each 'segment' of the curled ends. By default there are 20 segments ('num' in the page source).

Comment 3

[Kartikaya Gupta (email:[e-mail])]

Not really sure what to do about this one. I guess if we can make painting fast enough it would improve the behavior. I got a profile at https://cleopatra.io/#report=d3e2877c45b1eb0e0f1674ac4095a0baae2dd21a but nothing jumps out at me.

Comment 4

[Markus Stange [:mstange]]

This is a testcase where empty transactions for transform changes should actually help. But unfortunately we're not hitting that path. And the painting in the profile indicates that the transforms are not prerendered.

Comment 5

[Gregory Pappas [:gregp]]

This demo seems to perform well now. Should this bug be closed?

Comment 6

[Botond Ballo [:botond]]

Yes, let's close this. My guess is this was fixed by WebRender.