Pick the first or last baseline as appropriate

The old logic was always picking the last baseline, but this should only happen for inline-blocks. Since replaced elements and flex containers aren't currently setting their baselines, this is only an improvement for inline-tables.
servo · Mar 22, 2024 · 16ef6ff · 16ef6ff
1 parent 82813a6
commit 16ef6ff
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Showing 4 changed files with 61 additions and 4 deletions.
diff --git a/components/layout_2020/flow/inline.rs b/components/layout_2020/flow/inline.rs
@@ -101,7 +101,9 @@ use crate::cell::ArcRefCell;
 use crate::context::LayoutContext;
 use crate::flow::float::{FloatBox, SequentialLayoutState};
 use crate::flow::FlowLayout;
-use crate::formatting_contexts::{Baselines, IndependentFormattingContext};
+use crate::formatting_contexts::{
+    Baselines, IndependentFormattingContext, NonReplacedFormattingContextContents,
+};
 use crate::fragment_tree::{
     BaseFragmentInfo, BoxFragment, CollapsedBlockMargins, CollapsedMargin, Fragment, FragmentFlags,
     PositioningFragment,
@@ -2114,9 +2116,8 @@ impl IndependentFormattingContext {
         }
 
         let size = &pbm_sums.sum().into() + &fragment.content_rect.size;
-        let baseline_offset = fragment
-            .baselines
-            .last
+        let baseline_offset = self
+            .pick_baseline(&fragment.baselines)
             .map(|baseline| pbm_sums.block_start + baseline)
             .unwrap_or(size.block.into());
 
@@ -2139,6 +2140,18 @@ impl IndependentFormattingContext {
         ifc.have_deferred_soft_wrap_opportunity = true;
     }
 
+    /// Picks either the first or the last baseline, depending on `baseline-source`.
+    /// <https://drafts.csswg.org/css-inline/#baseline-source>
+    fn pick_baseline(&self, baselines: &Baselines) -> Option<Au> {
+        // TODO: Currently this only supports the initial `baseline-source: auto`.
+        if let Self::NonReplaced(non_replaced) = self {
+            if let NonReplacedFormattingContextContents::Flow(_) = non_replaced.contents {
+                return baselines.last;
+            }
+        }
+        baselines.first
+    }
+
     fn get_block_sizes_and_baseline_offset(
         &self,
         ifc: &InlineFormattingContextState,

diff --git a/tests/wpt/meta-legacy-layout/css/CSS2/tables/table-vertical-align-baseline-009.xht.ini b/tests/wpt/meta-legacy-layout/css/CSS2/tables/table-vertical-align-baseline-009.xht.ini
@@ -0,0 +1,2 @@
+[table-vertical-align-baseline-009.xht]
+  expected: FAIL
diff --git a/tests/wpt/meta/MANIFEST.json b/tests/wpt/meta/MANIFEST.json
@@ -106880,6 +106880,19 @@
         {}
        ]
       ],
+      "table-vertical-align-baseline-009.xht": [
+       "4620848ddc19661b5ddfaa34cefc9c9eee266dcb",
+       [
+        null,
+        [
+         [
+          "/css/CSS2/reference/ref-filled-green-100px-square.xht",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
       "table-visual-layout-017.xht": [
        "25067cb68385a520a10a31949d742b520c7e9cd6",
        [

diff --git a/tests/wpt/tests/css/CSS2/tables/table-vertical-align-baseline-009.xht b/tests/wpt/tests/css/CSS2/tables/table-vertical-align-baseline-009.xht
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml">
+ <head>
+  <title>CSS Test: Test for baseline alignment of table cells</title>
+  <link rel="author" title="Oriol Brufau" href="obrufau@igalia.com" />
+  <link rel="help" href="https://github.com/servo/servo/issues/31651" />
+  <link rel="help" href="https://drafts.csswg.org/css2/#height-layout" />
+  <link rel="match" href="../reference/ref-filled-green-100px-square.xht" />
+  <meta name="assert" content="The baseline of the table should be aligned with the baseline of the cell in the first row." />
+  <link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
+  <style><![CDATA[
+    span {
+      font: 50px/1 Ahem;
+      color: green;
+    }
+  ]]></style>
+ </head>
+ <body>
+  <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+  <div style="float: left; position: relative; font-size: 0; background: red">
+    <span style="position: absolute; left: 0; bottom: 0">X</span>
+    <span>X</span>
+    <span style="display: inline-table">
+      <span style="display: table-row">X</span>
+      <span style="display: table-row">X</span>
+    </span>
+  </div>
+ </body>
+</html>