[webkit-changes] [WebKit/WebKit] 1c78a5: [IFC] List bullets are aligned differently within ...

[Alan Baradlay]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 1c78a5cfb74b76035c0d2836a18e36ce2ed4db8c
      https://github.com/WebKit/WebKit/commit/1c78a5cfb74b76035c0d2836a18e36ce2ed4db8c
  Author: Alan Baradlay <zalan at apple.com>
  Date:   2023-06-23 (Fri, 23 Jun 2023)

  Changed paths:
    A LayoutTests/fast/inline/list-marker-inside-flex-expected.html
    A LayoutTests/fast/inline/list-marker-inside-flex.html
    M Source/WebCore/layout/integration/inline/LayoutIntegrationLineLayout.cpp

  Log Message:
  -----------
  [IFC] List bullets are aligned differently within a list when the list item has a flex container
https://bugs.webkit.org/show_bug.cgi?id=258414
<rdar://111066602>

Reviewed by Antti Koivisto.

Let's account for the box logical left position when computing the adjustment for outside list markers inside flex/grid.

In many cases outside list marker renderers end up inside descendant blocks ("closest" to the inline content on line) while their
horizontal position should ignore such "embedding".
Essentially they are supposed to show up at the same horizontal position regardless of how many generated/non-generated blocks
there are between the (tree) position of the RenderListMarker and the associated RenderListItem.
e.g.
  <li>
    <div style="display: flex;">
      <div style="width: 100px; height: 100px;"></div>
      <div id=inline_content>this is where the list marker gets inserted</div>
    </div>
  </li>
While the list marker is visually placed at the left side of <li>, it is placed under <div id=inline_content>.

offsetFromParentListItem is supposed to resolve this by climbing up the ancestor chain and accumulating
padding and border on the (logical) left between the RenderListMarker and RenderListItem. With flex/grid layout there
could be some additional offset between those renderers (other flex/grid items).
This patch fixes such cases by taking logical left into account for such content (sadly we can't have a uniform approach to this since
(in the render tree) block content does not get its final position until after this code runs. Moreover stale logicalLeft (leftover from previous
layout could lead to misplaced list markers. Legacy line layout addresses this by computing this offset (and moving the list marker!) _after_
layout at overflow computation time (see RenderListMarker::addOverflowFromListMarker)
In full LFC this will be fixed by inserting the marker box where it belongs).

* LayoutTests/fast/inline/list-marker-inside-flex-expected.html: Added.
* LayoutTests/fast/inline/list-marker-inside-flex.html: Added.
* Source/WebCore/layout/integration/inline/LayoutIntegrationLineLayout.cpp:
(WebCore::LayoutIntegration::LineLayout::updateListMarkerDimensions):

Canonical link: https://commits.webkit.org/265464@main