Table layout: Fix min-width distribution for spanning cells across mixed percent/auto columns

Ahmad-S792 · Ahmad Saleem · commit 273c6381a3c3 · 2026-01-07T07:14:58.000-08:00
https://bugs305120@main.webkit.org/show_bug.cgi?id=305042 rdar://167684748 Reviewed by Alan Baradlay. This patch undo some renering progressions from 305120@main where we shipped correct rendering but it broke distribution and caused tables to be wide in linked test case (in bugzilla - also converted to regression test case). i.e., table was ~770 pixel instead of 602 but with correct rendering. This patch will give us same rendering albeit incorrect as of shipping Safari, although it does not negate our 305120@main fully and we still progress a lot of test cases - which is right step to do. When a spanning cell covers columns with a mix of percentages, fixed widths, and auto widths, the distribution logic needs to account for fixed-width columns separately. The new code path for distributing min/max widths based on effective percentages should only apply when there are no fixed-width columns in the span. The fix adds a check for fixedWidth <= 0 to ensure the new distribution logic only runs when the span contains only percent and auto columns, allowing the existing else block to handle the mixed fixed+percent+auto case correctly. * Source/WebCore/rendering/AutoTableLayout.cpp: (WebCore::AutoTableLayout::calcEffectiveLogicalWidth): * LayoutTests/fast/table/table-colspan-mixed-percent-fixed-auto-expected.txt: Added. * LayoutTests/fast/table/table-colspan-mixed-percent-fixed-auto.html: Added. ^ So we don't regress it in future. It checks width (not rendering). Canonical link: https://commits.webkit.org/305215@main
diff --git a/LayoutTests/fast/table/table-colspan-mixed-percent-fixed-auto-expected.txt b/LayoutTests/fast/table/table-colspan-mixed-percent-fixed-auto-expected.txt
@@ -0,0 +1,10 @@
+P
+A
+F
+F
+A
+P
+Lorem
+
+PASS Table with mixed percent, fixed, and auto columns should respect width attribute
+
diff --git a/LayoutTests/fast/table/table-colspan-mixed-percent-fixed-auto.html b/LayoutTests/fast/table/table-colspan-mixed-percent-fixed-auto.html
@@ -0,0 +1,55 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title>Table layout with mixed percent, fixed, and auto columns with colspan</title>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+<style>
+table {
+    border: 1px solid black;
+    border-collapse: collapse;
+}
+td {
+    border: 1px solid black;
+    padding: 0;
+}
+</style>
+</head>
+<body>
+<table id="testTable" border width="600" cellspacing="0" cellpadding="0">
+    <tr>
+        <td width="50%">
+            <div style="width: 50px; background-color: violet;">P</div>
+        </td>
+        <td>
+            <div style="width: 50px; background-color: orange;">A</div>
+        </td>
+        <td width="50px">
+            <div style="background-color: green;">F</div>
+        </td>
+        <td width="50px">
+            <div style="background-color: green;">F</div>
+        </td>
+        <td>
+            <div style="width: 100px; background-color: orange;">A</div>
+        </td>
+        <td width="50%">
+            <div style="width: 50px; background-color: violet;">P</div>
+        </td>
+    </tr>
+    <tr>
+        <td width="100%" colspan="6">
+            <div style="width: 600px; background-color: lightblue;">Lorem</div>
+        </td>
+    </tr>
+</table>
+
+<script>
+test(function() {
+    var table = document.getElementById('testTable');
+    var tableWidth = table.offsetWidth;
+    assert_equals(tableWidth, 602, 'Table width should be 602px');
+}, 'Table with mixed percent, fixed, and auto columns should respect width attribute');
+</script>
+</body>
+</html>
diff --git a/Source/WebCore/rendering/AutoTableLayout.cpp b/Source/WebCore/rendering/AutoTableLayout.cpp
@@ -457,7 +457,7 @@ float AutoTableLayout::calcEffectiveLogicalWidth()
                 ASSERT(allocatedMinLogicalWidth < cellMinLogicalWidth || WTF::areEssentiallyEqual(allocatedMinLogicalWidth, cellMinLogicalWidth));
                 ASSERT(allocatedMaxLogicalWidth < cellMaxLogicalWidth || WTF::areEssentiallyEqual(allocatedMaxLogicalWidth, cellMaxLogicalWidth));
                 cellMaxLogicalWidth -= allocatedMaxLogicalWidth;
-            } else if (!allColsAreFixed && totalPercent > 0 && haveAuto) {
+            } else if (!allColsAreFixed && fixedWidth <= 0 && totalPercent > 0 && haveAuto) {
                 // By this point, the earlier code has converted auto columns to effectiveLogicalWidth percentages,
                 // so we can use the same percentage-based distribution as the allColsArePercent case.
 #if ASSERT_ENABLED

-Original file line number
+Diff line change
@@ @@ -0,0 +1,10 @@ @@
 +P
 +A
 +F
 +F
 +A
 +P
 +Lorem
++
 +PASS Table with mixed percent, fixed, and auto columns should respect width attribute
++