1960755 - Incorrect position of the box when using scrollbar-gutter on the root

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[Boris Chiou [:boris]]

Attachment: testcase

When I was checking this test, snapshot-containing-block-static.html, I noticed the target element has some weird behavior after we do scrolling.

If we don't call scrollTo() before startViewTransition(), everything looks normal. However, if we scroll a little bit, and then start the view transition, the rendering result of target element looks incorrect. It seems like we use the incorrect rect to take the snapshot of it, or maybe other issues?

Steps to reproduce:

1. Run the testcase

The expected result:
we should see a 100x100 green rectangle.

The actual result:
I saw a 100x50 (or 100x45, the height looks like less than 50px) green rectangle.

Comment 1

[Boris Chiou [:boris]]

Attachment: Firefox Nightly

Comment 2

[Boris Chiou [:boris]]

Attachment: Google Chrome (the expected result I think)

Comment 3

[Boris Chiou [:boris]]

Change to [viewtransition:m2] because this is still reproducible.

I will close this once other bugs fix this as well.

Comment 4

[Boris Chiou [:boris]]

The testcase I uploaded is not reproducible.

However, I think we could change this bug title for this test failure:
snapshot-containing-block-includes-scrollbar-gutter.html

For more specifically, the rendering result looks like the position of this box is not correct. Perhaps it is due to the scrollbar-gutter (i.e. the user wants to reserve space for the scrollbar).

Comment 5

[Boris Chiou [:boris]]

The interesting thing is, the rendering result is correct if I simply run it with mach run.

Comment 6

[Emilio Cobos Álvarez [:emilio]]

That's because wpt forces non-overlay scrollbars

Comment 7

[Boris Chiou [:boris]]

(In reply to Emilio Cobos Álvarez (:emilio) from comment #6)

That's because wpt forces non-overlay scrollbars

Right. I have to change my mac system setup to show the scrollbar always (i.e. non-overlay scrollbar I guess) to reproduce this test failure.

Comment 8

[Boris Chiou [:boris]]

So looks like this is a regression of my previous patch of snapshot containing block. It should include the scrollbar gutter.

Comment 9

[Boris Chiou [:boris]]

Attachment: Bug 1960755 - Tweak the rect of snapshot containing block to include scrollbar-gutter.

Setting the ua style with inset:0 may not be enough because the spec
expects us to include any scrollbar-gutters. So we dynamically set the
inset based on its scrollbar-gutter values.

Comment 10

[Boris Chiou [:boris]]

Attachment: Bug 1960755 - Specialize the reflow input and the containing block for snapshot containing block.

Per spec, snapshot containing block should include scrollbar-gutter, so
we shouldn't adjust its position and size by the scrollbar sizes.
However, for the rest of children of viewport frame still need this
adjustment, so we move all the calculation into
nsAbsoluteContainingBlock::Reflow(), and choose the proper ReflowInput
and containing block for different frames.

Comment 11

[Boris Chiou [:boris]]

Attachment: Bug 1960755 - Replace pointer with reference in ViewportFrame::AdjustReflowInputAsContainingBlock().

This function may be used outside ViewportFrame, and we expect its
parameter, ReflowInput, is non-null always, so use reference to avoid
any accidents.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/98ffe096b826
https://hg.mozilla.org/integration/autoland/rev/83d337396839
Replace pointer with reference in ViewportFrame::AdjustReflowInputAsContainingBlock(). r=TYLin
https://github.com/mozilla-firefox/firefox/commit/32d77c48fe71
https://hg.mozilla.org/integration/autoland/rev/625d9e32d01d
Specialize the reflow input and the containing block for snapshot containing block. r=layout-reviewers,view-transitions-reviewers,emilio,firefox-style-system-reviewers
https://github.com/mozilla-firefox/firefox/commit/59ad26a1eb3e
https://hg.mozilla.org/integration/autoland/rev/5d31a5f72a2e
apply code formatting via Lando

Comment 13

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/83d337396839
https://hg.mozilla.org/mozilla-central/rev/625d9e32d01d
https://hg.mozilla.org/mozilla-central/rev/5d31a5f72a2e