[line-clamp] Fix bug with line-breaking ellipsis inserted in last line #51539
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With line-clamp, if the line that would have the ellipsis happens to be the last line in the line-clamp container, then it must not have the ellipsis. In the spec's terms, there cannot be a region break (or a clamp point) at the end of the container. The way this was implemented was by laying out first with the ellipsis, and then doing a relayout without ellipsizing if we detected that there were no lines after it. However, this was implemented when the ellipsis simply hid content from the line. With the line breaking ellipsis the spec requires, which we are implementing under the `CSSLineClampLineBreakingEllipsis` flag, the presence of the ellipsis can push content to the next line, which can make a line no longer the last line. The behavior that is almost certainly expected is that in such cases, the line would not have the ellipsis. To implement this, we detect whether an ellipsized line would be the last line of its IFC if it didn't have the ellipsis. We implement this in `InlineLayoutAlgorithm::DoesRemainderFitInLineWithoutEllipsis`, which tries to compute that based on item metrics, and it returns `nullopt` to indicate that this cannot be computed without `LineBreaker`. Then, the `LayoutResult::WouldBeLastLineIfNotForEllipsis` flag is set. In the block layout algorithm's `BlockLineClampData`, if we're clamping by a number of lines, and we've just laid out a line box with the `WouldBeLastLineIfNotForEllipsis`, then we set a flag that will make any further calls to `BlockLineClampData::UpdateAfterLayout` ignore any further lines for the purposes of decreasing the number of lines until clamp. This will mean that any remaining lines in the same IFC will not be counted when determining whether we should relayout without ellipsizing. Bug: 40336192 Change-Id: Ie28f65b02f1adcb5b7f55ac52e55d0103788ea56 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6361775 Commit-Queue: Andreu Botella <[email protected]> Reviewed-by: Koji Ishii <[email protected]> Cr-Commit-Position: refs/heads/main@{#1436702}
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With line-clamp, if the line that would have the ellipsis happens to
be the last line in the line-clamp container, then it must not have
the ellipsis. In the spec's terms, there cannot be a region break (or
a clamp point) at the end of the container. The way this was
implemented was by laying out first with the ellipsis, and then doing
a relayout without ellipsizing if we detected that there were no lines
after it.
However, this was implemented when the ellipsis simply hid content
from the line. With the line breaking ellipsis the spec requires,
which we are implementing under the
CSSLineClampLineBreakingEllipsisflag, the presence of the ellipsis can push content to the next line,
which can make a line no longer the last line.
The behavior that is almost certainly expected is that in such cases,
the line would not have the ellipsis. To implement this, we detect
whether an ellipsized line would be the last line of its IFC if it
didn't have the ellipsis. We implement this in
InlineLayoutAlgorithm::DoesRemainderFitInLineWithoutEllipsis, whichtries to compute that based on item metrics, and it returns
nulloptto indicate that this cannot be computed without
LineBreaker. Then,the
LayoutResult::WouldBeLastLineIfNotForEllipsisflag is set.In the block layout algorithm's
BlockLineClampData, if we'reclamping by a number of lines, and we've just laid out a line box with
the
WouldBeLastLineIfNotForEllipsis, then we set a flag that willmake any further calls to
BlockLineClampData::UpdateAfterLayoutignore any further lines for the purposes of decreasing the number of
lines until clamp. This will mean that any remaining lines in the same
IFC will not be counted when determining whether we should relayout
without ellipsizing.
Bug: 40336192
Change-Id: Ie28f65b02f1adcb5b7f55ac52e55d0103788ea56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6361775
Commit-Queue: Andreu Botella <[email protected]>
Reviewed-by: Koji Ishii <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1436702}