From b4589134c9d3a4ba20f0805d4aa93fa55ca3e99e Mon Sep 17 00:00:00 2001
From: Oriol Brufau <obrufau@igalia.com>
Date: Tue, 19 Aug 2025 07:09:17 -0700
Subject: [PATCH] layout: Fix mix-ups between physical and logical aspect
 ratios (#38778)

`ComputedValuesExt::preferred_aspect_ratio()` was getting the natural
aspect ratio expressed logically as inline over block, but then it was
mixing it with the value of the `aspect-ratio` CSS property, which is
expressed physically as width over height.

Therefore, this changes `ComputedValuesExt::preferred_aspect_ratio()` to
expect the physical natural ratio, and then it takes care to convert the
resulting ratio logically.

Testing: Unneeded. This has no effect in practice because we don't
support `writing-mode` yet.

Signed-off-by: Oriol Brufau <obrufau@igalia.com>
---
 components/layout/replaced.rs  | 18 +-----------------
 components/layout/style_ext.rs | 27 ++++++++++++++++++---------
 2 files changed, 19 insertions(+), 26 deletions(-)

diff --git a/components/layout/replaced.rs b/components/layout/replaced.rs
index 468b3d96c50..95c9928b77d 100644
--- a/components/layout/replaced.rs
+++ b/components/layout/replaced.rs
@@ -267,19 +267,6 @@ impl ReplacedContents {
         }
     }
 
-    fn inline_size_over_block_size_intrinsic_ratio(
-        &self,
-        style: &ComputedValues,
-    ) -> Option<CSSFloat> {
-        self.natural_size.ratio.map(|width_over_height| {
-            if style.writing_mode.is_vertical() {
-                1. / width_over_height
-            } else {
-                width_over_height
-            }
-        })
-    }
-
     #[inline]
     fn content_size(
         &self,
@@ -474,10 +461,7 @@ impl ReplacedContents {
         style: &ComputedValues,
         padding_border_sums: &LogicalVec2<Au>,
     ) -> Option<AspectRatio> {
-        style.preferred_aspect_ratio(
-            self.inline_size_over_block_size_intrinsic_ratio(style),
-            padding_border_sums,
-        )
+        style.preferred_aspect_ratio(self.natural_size.ratio, padding_border_sums)
     }
 
     /// The inline size that would result from combining the natural size
diff --git a/components/layout/style_ext.rs b/components/layout/style_ext.rs
index bc327600e69..ff539716be8 100644
--- a/components/layout/style_ext.rs
+++ b/components/layout/style_ext.rs
@@ -225,7 +225,7 @@ impl AspectRatio {
         }
     }
 
-    pub(crate) fn from_content_ratio(i_over_b: CSSFloat) -> Self {
+    pub(crate) fn from_logical_content_ratio(i_over_b: CSSFloat) -> Self {
         Self {
             box_sizing_adjustment: LogicalVec2::zero(),
             i_over_b,
@@ -891,6 +891,14 @@ impl ComputedValuesExt for ComputedValues {
             preferred_ratio = PreferredRatio::None;
         }
 
+        let to_logical_ratio = |physical_ratio| {
+            if self.writing_mode.is_horizontal() {
+                physical_ratio
+            } else {
+                1.0 / physical_ratio
+            }
+        };
+
         match (auto, preferred_ratio) {
             // The value `auto`. Either the ratio was not specified, or was
             // degenerate and set to PreferredRatio::None above.
@@ -899,19 +907,20 @@ impl ComputedValuesExt for ComputedValues {
             // ratio; otherwise the box has no preferred aspect ratio. Size
             // calculations involving the aspect ratio work with the content box
             // dimensions always."
-            (_, PreferredRatio::None) => natural_aspect_ratio.map(AspectRatio::from_content_ratio),
+            (_, PreferredRatio::None) => natural_aspect_ratio
+                .map(to_logical_ratio)
+                .map(AspectRatio::from_logical_content_ratio),
             // "If both auto and a <ratio> are specified together, the preferred
             // aspect ratio is the specified ratio of width / height unless it
             // is a replaced element with a natural aspect ratio, in which case
             // that aspect ratio is used instead. In all cases, size
             // calculations involving the aspect ratio work with the content box
             // dimensions always."
-            (true, PreferredRatio::Ratio(preferred_ratio)) => {
-                Some(AspectRatio::from_content_ratio(
-                    natural_aspect_ratio
-                        .unwrap_or_else(|| (preferred_ratio.0).0 / (preferred_ratio.1).0),
-                ))
-            },
+            (true, PreferredRatio::Ratio(preferred_ratio)) => Some({
+                let physical_ratio = natural_aspect_ratio
+                    .unwrap_or_else(|| (preferred_ratio.0).0 / (preferred_ratio.1).0);
+                AspectRatio::from_logical_content_ratio(to_logical_ratio(physical_ratio))
+            }),
 
             // "The box’s preferred aspect ratio is the specified ratio of width
             // / height. Size calculations involving the aspect ratio work with
@@ -924,7 +933,7 @@ impl ComputedValuesExt for ComputedValues {
                     BoxSizing::BorderBox => *padding_border_sums,
                 };
                 Some(AspectRatio {
-                    i_over_b: (preferred_ratio.0).0 / (preferred_ratio.1).0,
+                    i_over_b: to_logical_ratio((preferred_ratio.0).0 / (preferred_ratio.1).0),
                     box_sizing_adjustment,
                 })
             },