<marquee> stretches a table and causes layout issues

Ahmad-S792 · Ahmad Saleem · commit 6079da9e03f1 · 2026-01-22T21:27:43.000-08:00
https://bugs.webkit.org/show_bug.cgi?id=41562 rdar://problem/99826593 Reviewed by Alan Baradlay. This patch aligns WebKit with Gecko / Firefox and Blink / Chromium. The special case in RenderBlockFlow::computeIntrinsicLogicalWidths() that sets minLogicalWidth to 0 for horizontal marquees was incorrectly gated behind a childrenInline() check. This caused marquees containing block children (e.g., a <div>) to use their content's preferred width instead of being treated as having no minimum width. Horizontal marquees scroll their content and should not constrain their container's width, regardless of whether their children are inline or block elements. The autoWrap() check already ensures this code only runs for marquees (which set white-space: nowrap). This fixes tables with fixed widths being incorrectly expanded when they contain marquees with block children. While here, we also wrapped the logic into `resetMinimumWidthForMarqueeIfApplicable` lambda (thanks to Alan). Test: fast/table/marquee-block-child-table-width.html * Source/WebCore/rendering/RenderBlockFlow.cpp: (WebCore::RenderBlockFlow::computeIntrinsicLogicalWidths const): Remove the childrenInline() check from the horizontal marquee special case, and update the comment to reflect that this applies to all horizontal marquees and wrap the logic in lambda. Canonical link: https://commits.webkit.org/306059@main
diff --git a/LayoutTests/fast/table/marquee-block-child-table-width-expected.txt b/LayoutTests/fast/table/marquee-block-child-table-width-expected.txt
@@ -0,0 +1,4 @@
+Text that has to wrap at a width of 200px!!!!
+
+PASS Horizontal marquee with block children does not expand parent table width
+
diff --git a/LayoutTests/fast/table/marquee-block-child-table-width.html b/LayoutTests/fast/table/marquee-block-child-table-width.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Horizontal marquee with block children should not expand table width</title>
+    <script src="../../resources/testharness.js"></script>
+    <script src="../../resources/testharnessreport.js"></script>
+</head>
+<body>
+    <table id="test-table" width="200" style="background:red">
+      <tr>
+        <td>
+          <marquee><div>Text that has to wrap at a width of 200px!!!!</div></marquee>
+        </td>
+      </tr>
+    </table>
+    
+    <script>
+        test(function() {
+            var table = document.getElementById('test-table');
+            var computedWidth = parseFloat(window.getComputedStyle(table).width);
+            assert_equals(computedWidth, 200, 
+                "Table width should be 200px despite marquee containing wide block content");
+        }, "Horizontal marquee with block children does not expand parent table width");
+    </script>
+</body>
+</html>
diff --git a/Source/WebCore/rendering/RenderBlockFlow.cpp b/Source/WebCore/rendering/RenderBlockFlow.cpp
@@ -2,7 +2,7 @@
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
- * Copyright (C) 2003-2025 Apple Inc. All rights reserved.
+ * Copyright (C) 2003-2026 Apple Inc. All rights reserved.
  * Copyright (C) 2014-2016 Google Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
@@ -358,12 +358,16 @@ void RenderBlockFlow::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth,
     if (needAdjustIntrinsicLogicalWidthsForColumns)
         adjustIntrinsicLogicalWidthsForColumns(minLogicalWidth, maxLogicalWidth);
 
-    if (!style().autoWrap() && childrenInline()) {
-        // A horizontal marquee with inline children has no minimum width.
-        CheckedPtr scrollableArea = layer() ? layer()->scrollableArea() : nullptr;
-        if (scrollableArea && scrollableArea->marquee() && scrollableArea->marquee()->isHorizontal())
-            minLogicalWidth = 0;
-    }
+    auto resetMinimumWidthForMarqueeIfApplicable = [&] {
+        if (style().autoWrap() || !layer())
+            return;
+        CheckedPtr scrollableArea = layer()->scrollableArea();
+        if (!scrollableArea || !scrollableArea->marquee() || !scrollableArea->marquee()->isHorizontal())
+            return;
+        // A horizontal marquee has no minimum width.
+        minLogicalWidth = { };
+    };
+    resetMinimumWidthForMarqueeIfApplicable();
 
     if (auto* cell = dynamicDowncast<RenderTableCell>(*this)) {
         auto [ tableCellWidth, usedZoom ] = cell->styleOrColLogicalWidth();

-Original file line number
+Diff line change
@@ @@ -0,0 +1,4 @@ @@
 +Text that has to wrap at a width of 200px!!!!
++
 +PASS Horizontal marquee with block children does not expand parent table width
++