tree 927d82815c81c332f32ebe71afa172e926acbd50
parent 7d187abfafc8910e2cecc76df38abe12e90b4b48
author Ting-Yu Lin <tlin@mozilla.com> 1596849765 +0000
committer moz-wptsync-bot <wptsync@mozilla.com> 1596895284 +0100

Part 4 - Reflow lines with pushed floats under constrained available block-size or in paginated context.

When a clearance frame is discovered in a BFC
subtree (`ReflowInput::WillReflowAgainForClearance()` is true), all the
block descendants of the BFC return from `ReflowBlockFrame` immediately
without placing their children or requesting continuation for their
children, etc., because the BFC is going to reflow the subtree a
second time.

When this happens, any block descendant whose lines contain pushed
floats should be marked dirty and reflowed again so that they can go
through all the split floats logic and set their nsReflowStatus to
incomplete/overflow-incomplete correctly. (We may develop a smarter way
in bug 851629 to make the performance better.)

The condition `aState.mPresContext->IsPaginated()` is added to prevent
1406291-1.html from failing. In 1406291-1.html, the table containing the
float in its subtree is being pushed to the second page due to force
break, and the float is in PushedFloatsList of its parent block. When we
reflow the block again (in the second page), it is reflowed under the
measuring stage of the table layout with unconstrained available
block-size. nsBlockFrame::DrainSelfPushedFloats() deliberately doesn't
drain pushed floats if their placehoder are in the same block, and
expect the floats to be reflowed again. Before this patch, the line can
be marked dirty via HasPushedFloats(), but in this patch,
HasPushedFloats() is moved into the nested if-else, so we need
`aState.mPresContext->IsPaginated()` to let the block know that it's in
a paginated context, and needs to reflow any line that contains pushed
floats.

Differential Revision: https://phabricator.services.mozilla.com/D85480

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1559961
gecko-commit: db613effb20bfd4e703c164d2f464cc22b97e2a8
gecko-integration-branch: autoland
gecko-reviewers: dholbert