commit 77af2ba39e832dbcb39aba0b7eccb2f2dab4afc8
author Morten Stenshorne <mstensho@chromium.org> Thu Jan 05 09:24:02 2023
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> Thu Jan 05 09:36:39 2023
tree 6af83bc0a94f8371e2942722a19cd6f2afdb3137
parent f4b42e47acdd9eecaf6d269a9aa4f766b251a4c9

Better handling of OOFs inside clipped containers.

If we're inside a fragmentation context, and the containing block of an
out-of-flow positioned element is inside a container that clips block
direction overflow, keep track of the offset to the clipping container.

This is used by printing, as an attempt to prevent the OOF from ending
up in a fragmentainer that precedes the fragmentainer that contains the
clipping container. This helps pre-paint set the correct clip rectangle.
If the OOF ends up in an earlier fragmentainer, we would have no idea
what clip rectangle to use, since the clipping container isn't
represented there.

This eliminates the need for the is_fragmented_inside_clipped_container
flag, since the new approach provides the same information, and more.
Besides, we failed to update is_fragmented_inside_clipped_container in
nested OOF situations, so that the inner OOF wouldn't see any clipped
container established by the containing block (or an ancestor) of the
outer OOF. Rather than fixing the redundant flag, remove it.

Some of the printing tests look sillier than I'd like, but this is due
to the fact that when generating print output, content that should have
been hidden entirely by clipping still bleeds through.

This behavior change is limited to printing. It doesn't really make
sense to do the same for multicol, since columns are laid out in the
inline direction. The previous column isn't visually above the next
column, so it wouldn't look right. For printing the previous page is
just above the next page, visually, though. The new multicol tests in
this CL are there just to illustrate that we don't want this behavior
in multicol. They also pass without this CL.

Bug: 1400739
Change-Id: Ie05a9427dab454e7b1481bab1e05286f9c64d943
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4136240
Reviewed-by: Alison Maher <almaher@microsoft.com>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1089157}