[webkit-changes] [WebKit/WebKit] 7ca5a9: [IFC] Stop placing previously suspended floats on ...

[Alan Baradlay]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 7ca5a9d0bf70542a737d9bb926910cf8e654b556
      https://github.com/WebKit/WebKit/commit/7ca5a9d0bf70542a737d9bb926910cf8e654b556
  Author: Alan Baradlay <zalan at apple.com>
  Date:   2023-09-05 (Tue, 05 Sep 2023)

  Changed paths:
    M Source/WebCore/layout/formattingContexts/inline/InlineLineBuilder.cpp
    M Source/WebCore/layout/formattingContexts/inline/InlineLineBuilder.h

  Log Message:
  -----------
  [IFC] Stop placing previously suspended floats on over-constrained line
https://bugs.webkit.org/show_bug.cgi?id=261078

Reviewed by Antti Koivisto.

1. When a float over-constrains a line (i.e. shrink it to zero horizontal available space) we suspend float layout but continue with laying out inline content until line breaking.
2. Any additional float we find until line breaking gets added to a suspended list (see InlineLineBuilder::m_suspendedFloats).
3. This suspended list of floats is input to next line building. We start processing such floats before looking at inline content.
(this is trunk behavior)

In case of multiple floats in the suspended list, we may get into a situation when we can't place all of these floats on the current line (over-constraining)
Currently we continue placing over-constraining floats according to normal float layout (in practice it means we start placing floats "under" the current line box).

This patch changes this behavior by
1. letting only the first suspended float over-constrain the line and if we don't have any available space left
2. suspend float layout (again)
3. move over to the next line

In addition to keep line state consistent, this patch also helps to keep margin-trim logic simple (see InlineLineBuilder::m_lineIsConstrainedByFloat).

* Source/WebCore/layout/formattingContexts/inline/InlineLineBuilder.cpp:
(WebCore::Layout::LineBuilder::placeInlineAndFloatContent):
(WebCore::Layout::LineBuilder::shouldTryToPlaceFloatBox const):
* Source/WebCore/layout/formattingContexts/inline/InlineLineBuilder.h:

Canonical link: https://commits.webkit.org/267631@main