Changeset 276634 in webkit

Timestamp:

Apr 27, 2021 3:15:02 AM (15 months ago)

Author:

svillar@igalia.com

Message:

[css-flexbox] percent children don't resolve against the flex basis on a fully inflexible item with fixed flex-basis
​https://bugs.webkit.org/show_bug.cgi?id=210478

Reviewed by Darin Adler.

Source/WebCore:

Flexbox spec defines some additional cases where sizes could be considered definite despite they are
actually indefinite. One of those cases is whenever we have a fully inflexible item with a definite
flex-basis. In that case we should allow desdendants of flex item to resolve against the post-flexing
size of the flex item which is basically the value of the definite flex-basis. Note that in the majority
of cases those percentages are resolved before flexing the item and not recomputed after that.

• rendering/RenderFlexibleBox.cpp:

(WebCore::RenderFlexibleBox::useChildOverridingMainSizeForPercentageResolution): let descendants of
fully inflexible flex items with definite flex-basis to resolve against the post-flexing size. Also added
some documentation because that part of the code is far from obvious for the casual reader.

LayoutTests:

• TestExpectations: Unskipped a couple of tests that are passing now.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/TestExpectations (modified) (1 diff)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderFlexibleBox.cpp (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2021-04-21  Sergio Villar Senin  <svillar@igalia.com>
+
+        [css-flexbox] percent children don't resolve against the flex basis on a fully inflexible item with fixed flex-basis
+        https://bugs.webkit.org/show_bug.cgi?id=210478
+
+        Reviewed by Darin Adler.
+
+        * TestExpectations: Unskipped a couple of tests that are passing now.
+
 2021-04-27  Rob Buis  <rbuis@igalia.com>
 

trunk/LayoutTests/TestExpectations

@@ -3910 +3910 @@
 webkit.org/b/210093 imported/w3c/web-platform-tests/css/css-flexbox/select-element-zero-height-002.html [ ImageOnlyFailure ]
 webkit.org/b/210144 imported/w3c/web-platform-tests/css/css-flexbox/anonymous-flex-item-005.html [ ImageOnlyFailure ]
-webkit.org/b/210478 imported/w3c/web-platform-tests/css/css-flexbox/percentage-heights-006.html [ ImageOnlyFailure ]
 webkit.org/b/212046 imported/w3c/web-platform-tests/css/css-flexbox/overflow-area-001.html [ ImageOnlyFailure ]
 webkit.org/b/212046 imported/w3c/web-platform-tests/css/css-flexbox/overflow-area-002.html [ ImageOnlyFailure ]
 webkit.org/b/212046 imported/w3c/web-platform-tests/css/css-flexbox/overflow-auto-005.html [ ImageOnlyFailure ]
-webkit.org/b/212046 imported/w3c/web-platform-tests/css/css-flexbox/percentage-heights-007.html [ ImageOnlyFailure ]
 webkit.org/b/212046 imported/w3c/web-platform-tests/css/css-flexbox/percentage-heights-014.html [ ImageOnlyFailure ]
 webkit.org/b/212046 imported/w3c/web-platform-tests/css/css-flexbox/scrollbars-auto.html [ ImageOnlyFailure ]

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2021-04-21  Sergio Villar Senin  <svillar@igalia.com>
+
+        [css-flexbox] percent children don't resolve against the flex basis on a fully inflexible item with fixed flex-basis
+        https://bugs.webkit.org/show_bug.cgi?id=210478
+
+        Reviewed by Darin Adler.
+
+        Flexbox spec defines some additional cases where sizes could be considered definite despite they are
+        actually indefinite. One of those cases is whenever we have a fully inflexible item with a definite
+        flex-basis. In that case we should allow desdendants of flex item to resolve against the post-flexing
+        size of the flex item which is basically the value of the definite flex-basis. Note that in the majority
+        of cases those percentages are resolved before flexing the item and not recomputed after that.
+
+        * rendering/RenderFlexibleBox.cpp:
+        (WebCore::RenderFlexibleBox::useChildOverridingMainSizeForPercentageResolution): let descendants of
+        fully inflexible flex items with definite flex-basis to resolve against the post-flexing size. Also added
+        some documentation because that part of the code is far from obvious for the casual reader.
+
 2021-04-27  Youenn Fablet  <youenn@apple.com>
 

trunk/Source/WebCore/rendering/RenderFlexibleBox.cpp

@@ -1242 +1242 @@
 }
 
+// This method is only called whenever a descendant of a flex item wants to resolve a percentage in its
+// block axis (logical height). The key here is that percentages should be generally resolved before the
+// flex item is flexed, meaning that they shouldn't be recomputed once the flex item has been flexed. There
+// are some exceptions though that are implemented here, like the case of fully inflexible items with
+// definite flex-basis, or whenever the flex container has a definite main size. See
+// https://drafts.csswg.org/css-flexbox/#definite-sizes for additional details.
 bool RenderFlexibleBox::useChildOverridingMainSizeForPercentageResolution(const RenderBox& child)
 {
     ASSERT(!mainAxisIsChildInlineAxis(child));
+
+    // The main size of a fully inflexible item with a definite flex basis is, by definition, definite.
+    if (child.style().flexGrow() == 0.0 && child.style().flexShrink() == 0.0 && childMainSizeIsDefinite(child, flexBasisForChild(child)))
+        return child.hasOverridingLogicalHeight();
+
     // This function implements section 9.8. Definite and Indefinite Sizes, case 2) of the flexbox spec.
     // If the flex container has a definite main size the flex item post-flexing main size is also treated
     // as definite. We make up a percentage to check whether we have a definite size.
-    auto updateDescendants = m_inLayout ? UpdatePercentageHeightDescendants::Yes : UpdatePercentageHeightDescendants::No;
-    if (!canComputePercentageFlexBasis(child, Length(0, LengthType::Percent), updateDescendants))
+    if (!canComputePercentageFlexBasis(child, Length(0, LengthType::Percent), UpdatePercentageHeightDescendants::Yes))
         return false;