Auto merge of #25207 - servo:replaced, r=nox

min/max-width/height, replaced elements

components/layout_2020/dom_traversal.rs

@@ -17,7 +17,6 @@ use std::sync::Arc;
 use style::dom::TNode;
 use style::properties::ComputedValues;
 use style::selector_parser::PseudoElement;
-use style::values::computed::Length;
 
 #[derive(Clone, Copy)]
 pub enum WhichPseudoElement {
@@ -299,7 +298,10 @@ impl Drop for BoxSlot<'_> {
 pub(crate) trait NodeExt<'dom>: 'dom + Copy + LayoutNode + Send + Sync {
     fn is_element(self) -> bool;
     fn as_text(self) -> Option<String>;
-    fn as_image(self) -> Option<(Option<Arc<NetImage>>, Vec2<Length>)>;
+
+    /// Returns the image if it’s loaded, and its size in image pixels
+    /// adjusted for `image_density`.
+    fn as_image(self) -> Option<(Option<Arc<NetImage>>, Vec2<f64>)>;
     fn first_child(self) -> Option<Self>;
     fn next_sibling(self) -> Option<Self>;
     fn parent_node(self) -> Option<Self>;
@@ -328,7 +330,7 @@ where
         }
     }
 
-    fn as_image(self) -> Option<(Option<Arc<NetImage>>, Vec2<Length>)> {
+    fn as_image(self) -> Option<(Option<Arc<NetImage>>, Vec2<f64>)> {
         let node = self.to_threadsafe();
         let (resource, metadata) = node.image_data()?;
         let (width, height) = resource
@@ -336,14 +338,14 @@ where
             .map(|image| (image.width, image.height))
             .or_else(|| metadata.map(|metadata| (metadata.width, metadata.height)))
             .unwrap_or((0, 0));
-        let (mut width, mut height) = (width as f32, height as f32);
+        let (mut width, mut height) = (width as f64, height as f64);
         if let Some(density) = node.image_density().filter(|density| *density != 1.) {
-            width = (width as f64 / density) as f32;
+            width = width / density;
-            height = (height as f64 / density) as f32;
+            height = height / density;
         }
         let size = Vec2 {
-            x: Length::new(width),
+            x: width,
-            y: Length::new(height),
+            y: height,
         };
         Some((resource, size))
     }

components/layout_2020/flow/construct.rs

@@ -393,7 +393,7 @@ where
                     style.clone(),
                     display_inside,
                     contents,
-                    ContentSizesRequest::inline_if(style.inline_size_is_auto()),
+                    ContentSizesRequest::inline_if(!style.inline_size_is_length()),
                 ),
             ))
         };
@@ -590,7 +590,7 @@ where
                     &style,
                     ContentSizesRequest::inline_if(
                         max_assign_in_flow_outer_content_sizes_to.is_some() &&
-                            style.inline_size_is_auto(),
+                            !style.inline_size_is_length(),
                     ),
                 );
                 if let Some(to) = max_assign_in_flow_outer_content_sizes_to {
@@ -607,7 +607,7 @@ where
             } => {
                 let content_sizes = ContentSizesRequest::inline_if(
                     max_assign_in_flow_outer_content_sizes_to.is_some() &&
-                        style.inline_size_is_auto(),
+                        !style.inline_size_is_length(),
                 );
                 let contents = IndependentFormattingContext::construct(
                     context,

components/layout_2020/flow/float.rs

@@ -33,7 +33,7 @@ impl FloatBox {
         display_inside: DisplayInside,
         contents: Contents<impl NodeExt<'dom>>,
     ) -> Self {
-        let content_sizes = ContentSizesRequest::inline_if(style.inline_size_is_auto());
+        let content_sizes = ContentSizesRequest::inline_if(!style.inline_size_is_length());
         Self {
             contents: IndependentFormattingContext::construct(
                 context,

components/layout_2020/flow/inline.rs

@@ -465,9 +465,7 @@ fn layout_atomic<'box_tree>(
 
     let fragment = match atomic.as_replaced() {
         Ok(replaced) => {
-            // FIXME: implement https://drafts.csswg.org/css2/visudet.html#inline-replaced-width
+            let size = replaced.used_size_as_if_inline_element(ifc.containing_block, &atomic.style);
-            // and https://drafts.csswg.org/css2/visudet.html#inline-replaced-height
-            let size = Vec2::zero();
             let fragments = replaced.make_fragments(&atomic.style, size.clone());
             let content_rect = Rect { start_corner, size };
             BoxFragment {
@@ -482,10 +480,29 @@ fn layout_atomic<'box_tree>(
         },
         Err(non_replaced) => {
             let box_size = atomic.style.box_size();
-            let inline_size = box_size.inline.percentage_relative_to(cbis).auto_is(|| {
+            let max_box_size = atomic
-                let available_size = cbis - pbm.inline_sum();
+                .style
-                atomic.content_sizes.shrink_to_fit(available_size)
+                .max_box_size()
-            });
+                .percentages_relative_to(ifc.containing_block);
+            let min_box_size = atomic
+                .style
+                .min_box_size()
+                .percentages_relative_to(ifc.containing_block)
+                .auto_is(Length::zero);
+
+            // https://drafts.csswg.org/css2/visudet.html#inlineblock-width
+            let tentative_inline_size =
+                box_size.inline.percentage_relative_to(cbis).auto_is(|| {
+                    let available_size = cbis - pbm.inline_sum();
+                    atomic.content_sizes.shrink_to_fit(available_size)
+                });
+
+            // https://drafts.csswg.org/css2/visudet.html#min-max-widths
+            // In this case “applying the rules above again” with a non-auto inline-size
+            // always results in that size.
+            let inline_size = tentative_inline_size
+                .clamp_between_extremums(min_box_size.inline, max_box_size.inline);
+
             let block_size = box_size
                 .block
                 .maybe_percentage_relative_to(ifc.containing_block.block_size.non_auto());
@@ -508,7 +525,16 @@ fn layout_atomic<'box_tree>(
                 dummy_tree_rank,
                 ifc.absolutely_positioned_fragments,
             );
-            let block_size = block_size.auto_is(|| independent_layout.content_block_size);
+
+            // https://drafts.csswg.org/css2/visudet.html#block-root-margin
+            let tentative_block_size = block_size.auto_is(|| independent_layout.content_block_size);
+
+            // https://drafts.csswg.org/css2/visudet.html#min-max-heights
+            // In this case “applying the rules above again” with a non-auto block-size
+            // always results in that size.
+            let block_size = tentative_block_size
+                .clamp_between_extremums(min_box_size.block, max_box_size.block);
+
             let content_rect = Rect {
                 start_corner,
                 size: Vec2 {

components/layout_2020/flow/mod.rs

@@ -21,8 +21,7 @@ use rayon_croissant::ParallelIteratorExt;
 use servo_arc::Arc;
 use style::computed_values::position::T as Position;
 use style::properties::ComputedValues;
-use style::values::computed::{Length, LengthOrAuto, LengthPercentage, LengthPercentageOrAuto};
+use style::values::computed::{Length, LengthOrAuto};
-use style::values::generics::length::MaxSize;
 use style::Zero;
 
 mod construct;
@@ -365,10 +364,14 @@ fn layout_in_flow_non_replaced_block_level<'a>(
     let pb = &padding + &border;
     let pb_inline_sum = pb.inline_sum();
 
-    let box_size = percent_resolved_box_size(style.box_size(), containing_block);
+    let box_size = style.box_size().percentages_relative_to(containing_block);
-    let max_box_size = percent_resolved_max_box_size(style.max_box_size(), containing_block);
+    let max_box_size = style
-    let min_box_size =
+        .max_box_size()
-        percent_resolved_box_size(style.min_box_size(), containing_block).auto_is(Length::zero);
+        .percentages_relative_to(containing_block);
+    let min_box_size = style
+        .min_box_size()
+        .percentages_relative_to(containing_block)
+        .auto_is(Length::zero);
 
     // https://drafts.csswg.org/css2/visudet.html#min-max-widths
     let solve_inline_margins = |inline_size| {
@@ -411,7 +414,7 @@ fn layout_in_flow_non_replaced_block_level<'a>(
     // https://drafts.csswg.org/css2/visudet.html#min-max-heights
     let mut block_size = box_size.block;
     if let LengthOrAuto::LengthPercentage(ref mut block_size) = block_size {
-        *block_size = clamp_between_extremums(*block_size, min_box_size.block, max_box_size.block);
+        *block_size = block_size.clamp_between_extremums(min_box_size.block, max_box_size.block);
     }
 
     let containing_block_for_children = ContainingBlock {
@@ -475,11 +478,9 @@ fn layout_in_flow_non_replaced_block_level<'a>(
                 .collapsed_through;
     let relative_adjustement = relative_adjustement(style, inline_size, block_size);
     let block_size = block_size.auto_is(|| {
-        clamp_between_extremums(
+        flow_layout
-            flow_layout.content_block_size,
+            .content_block_size
-            min_box_size.block,
+            .clamp_between_extremums(min_box_size.block, max_box_size.block)
-            max_box_size.block,
-        )
     });
     let content_rect = Rect {
         start_corner: Vec2 {
@@ -520,140 +521,20 @@ fn layout_in_flow_replaced_block_level<'a>(
     style: &Arc<ComputedValues>,
     replaced: &ReplacedContent,
 ) -> BoxFragment {
+    let size = replaced.used_size_as_if_inline_element(containing_block, style);
+
     let cbis = containing_block.inline_size;
     let padding = style.padding().percentages_relative_to(cbis);
     let border = style.border_width();
     let computed_margin = style.margin().percentages_relative_to(cbis);
     let pb = &padding + &border;
-    let mode = style.writing_mode;
-    // FIXME(nox): We shouldn't pretend we always have a fully known intrinsic size.
-    let intrinsic_size = replaced.intrinsic_size.size_to_flow_relative(mode);
-    // FIXME(nox): This can divide by zero.
-    let intrinsic_ratio = intrinsic_size.inline.px() / intrinsic_size.block.px();
-
-    let box_size = percent_resolved_box_size(style.box_size(), containing_block);
-    let min_box_size =
-        percent_resolved_box_size(style.min_box_size(), containing_block).auto_is(Length::zero);
-    let max_box_size = percent_resolved_max_box_size(style.max_box_size(), containing_block);
-
-    let clamp = |inline_size, block_size| {
-        (
-            clamp_between_extremums(inline_size, min_box_size.inline, max_box_size.inline),
-            clamp_between_extremums(block_size, min_box_size.block, max_box_size.block),
-        )
-    };
-    // https://drafts.csswg.org/css2/visudet.html#min-max-widths
-    // https://drafts.csswg.org/css2/visudet.html#min-max-heights
-    let (inline_size, block_size) = match (box_size.inline, box_size.block) {
-        (LengthOrAuto::LengthPercentage(inline), LengthOrAuto::LengthPercentage(block)) => {
-            clamp(inline, block)
-        },
-        (LengthOrAuto::LengthPercentage(inline), LengthOrAuto::Auto) => {
-            clamp(inline, inline / intrinsic_ratio)
-        },
-        (LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(block)) => {
-            clamp(block * intrinsic_ratio, block)
-        },
-        (LengthOrAuto::Auto, LengthOrAuto::Auto) => {
-            enum Violation {
-                None,
-                Below(Length),
-                Above(Length),
-            }
-            let violation = |size, min_size, mut max_size: Option<Length>| {
-                if let Some(max) = max_size.as_mut() {
-                    max.max_assign(min_size);
-                }
-                if size < min_size {
-                    return Violation::Below(min_size);
-                }
-                match max_size {
-                    Some(max_size) if size > max_size => Violation::Above(max_size),
-                    _ => Violation::None,
-                }
-            };
-            match (
-                violation(
-                    intrinsic_size.inline,
-                    min_box_size.inline,
-                    max_box_size.inline,
-                ),
-                violation(intrinsic_size.block, min_box_size.block, max_box_size.block),
-            ) {
-                // Row 1.
-                (Violation::None, Violation::None) => (intrinsic_size.inline, intrinsic_size.block),
-                // Row 2.
-                (Violation::Above(max_inline_size), Violation::None) => {
-                    let block_size = (max_inline_size / intrinsic_ratio).max(min_box_size.block);
-                    (max_inline_size, block_size)
-                },
-                // Row 3.
-                (Violation::Below(min_inline_size), Violation::None) => {
-                    let block_size =
-                        clamp_below_max(min_inline_size / intrinsic_ratio, max_box_size.block);
-                    (min_inline_size, block_size)
-                },
-                // Row 4.
-                (Violation::None, Violation::Above(max_block_size)) => {
-                    let inline_size = (max_block_size * intrinsic_ratio).max(min_box_size.inline);
-                    (inline_size, max_block_size)
-                },
-                // Row 5.
-                (Violation::None, Violation::Below(min_block_size)) => {
-                    let inline_size =
-                        clamp_below_max(min_block_size * intrinsic_ratio, max_box_size.inline);
-                    (inline_size, min_block_size)
-                },
-                // Rows 6-7.
-                (Violation::Above(max_inline_size), Violation::Above(max_block_size)) => {
-                    if max_inline_size.px() / intrinsic_size.inline.px() <=
-                        max_block_size.px() / intrinsic_size.block.px()
-                    {
-                        // Row 6.
-                        let block_size =
-                            (max_inline_size / intrinsic_ratio).max(min_box_size.block);
-                        (max_inline_size, block_size)
-                    } else {
-                        // Row 7.
-                        let inline_size =
-                            (max_block_size * intrinsic_ratio).max(min_box_size.inline);
-                        (inline_size, max_block_size)
-                    }
-                },
-                // Rows 8-9.
-                (Violation::Below(min_inline_size), Violation::Below(min_block_size)) => {
-                    if min_inline_size.px() / intrinsic_size.inline.px() <=
-                        min_block_size.px() / intrinsic_size.block.px()
-                    {
-                        // Row 8.
-                        let inline_size =
-                            clamp_below_max(min_block_size * intrinsic_ratio, max_box_size.inline);
-                        (inline_size, min_block_size)
-                    } else {
-                        // Row 9.
-                        let block_size =
-                            clamp_below_max(min_inline_size / intrinsic_ratio, max_box_size.block);
-                        (min_inline_size, block_size)
-                    }
-                },
-                // Row 10.
-                (Violation::Below(min_inline_size), Violation::Above(max_block_size)) => {
-                    (min_inline_size, max_block_size)
-                },
-                // Row 11.
-                (Violation::Above(max_inline_size), Violation::Below(min_block_size)) => {
-                    (max_inline_size, min_block_size)
-                },
-            }
-        },
-    };
 
     let (margin_inline_start, margin_inline_end) = solve_inline_margins_for_in_flow_block_level(
         containing_block,
         pb.inline_sum(),
         computed_margin.inline_start,
         computed_margin.inline_end,
-        inline_size,
+        size.inline,
     );
     let margin = Sides {
         inline_start: margin_inline_start,
@@ -661,15 +542,11 @@ fn layout_in_flow_replaced_block_level<'a>(
         block_start: computed_margin.block_start.auto_is(Length::zero),
         block_end: computed_margin.block_end.auto_is(Length::zero),
     };
-    let size = Vec2 {
-        block: block_size,
-        inline: inline_size,
-    };
     let fragments = replaced.make_fragments(style, size.clone());
     let relative_adjustement = relative_adjustement(
         style,
-        inline_size,
+        size.inline,
-        LengthOrAuto::LengthPercentage(block_size),
+        LengthOrAuto::LengthPercentage(size.block),
     );
     let content_rect = Rect {
         start_corner: Vec2 {
@@ -703,45 +580,3 @@ fn solve_inline_margins_for_in_flow_block_level(
         (LengthOrAuto::LengthPercentage(start), _) => (start, inline_margins - start),
     }
 }
-
-fn clamp_between_extremums(size: Length, min_size: Length, max_size: Option<Length>) -> Length {
-    clamp_below_max(size, max_size).max(min_size)
-}
-
-fn clamp_below_max(size: Length, max_size: Option<Length>) -> Length {
-    max_size.map_or(size, |max_size| size.min(max_size))
-}
-
-fn percent_resolved_box_size(
-    box_size: Vec2<LengthPercentageOrAuto>,
-    containing_block: &ContainingBlock,
-) -> Vec2<LengthOrAuto> {
-    Vec2 {
-        inline: box_size
-            .inline
-            .percentage_relative_to(containing_block.inline_size),
-        block: box_size
-            .block
-            .maybe_percentage_relative_to(containing_block.block_size.non_auto()),
-    }
-}
-
-fn percent_resolved_max_box_size(
-    max_box_size: Vec2<MaxSize<LengthPercentage>>,
-    containing_block: &ContainingBlock,
-) -> Vec2<Option<Length>> {
-    Vec2 {
-        inline: match max_box_size.inline {
-            MaxSize::LengthPercentage(max_inline_size) => {
-                Some(max_inline_size.percentage_relative_to(containing_block.inline_size))
-            },
-            MaxSize::None => None,
-        },
-        block: match max_box_size.block {
-            MaxSize::LengthPercentage(max_block_size) => {
-                max_block_size.maybe_percentage_relative_to(containing_block.block_size.non_auto())
-            },
-            MaxSize::None => None,
-        },
-    }
-}

components/layout_2020/flow/root.rs

@@ -16,12 +16,12 @@ use crate::positioned::AbsolutelyPositionedBox;
 use crate::replaced::ReplacedContent;
 use crate::sizing::ContentSizesRequest;
 use crate::style_ext::{Display, DisplayGeneratingBox, DisplayInside};
-use crate::{ContainingBlock, DefiniteContainingBlock};
+use crate::DefiniteContainingBlock;
 use rayon::iter::{IntoParallelRefIterator, ParallelExtend, ParallelIterator};
 use script_layout_interface::wrapper_traits::LayoutNode;
 use servo_arc::Arc;
 use style::properties::ComputedValues;
-use style::values::computed::{Length, LengthOrAuto};
+use style::values::computed::Length;
 use style::Zero;
 use style_traits::CSSPixel;
 
@@ -99,31 +99,25 @@ impl BoxTreeRoot {
         viewport: geom::Size<CSSPixel>,
     ) -> FragmentTreeRoot {
         let style = ComputedValues::initial_values();
-        let initial_containing_block_size = Vec2 {
+        let initial_containing_block = DefiniteContainingBlock {
-            inline: Length::new(viewport.width),
+            size: Vec2 {
-            block: Length::new(viewport.height),
+                inline: Length::new(viewport.width),
-        };
+                block: Length::new(viewport.height),
-
+            },
-        let initial_containing_block = ContainingBlock {
-            inline_size: initial_containing_block_size.inline,
-            block_size: LengthOrAuto::LengthPercentage(initial_containing_block_size.block),
             // FIXME: use the document’s mode:
             // https://drafts.csswg.org/css-writing-modes/#principal-flow
             style,
         };
+
         let dummy_tree_rank = 0;
         let mut absolutely_positioned_fragments = vec![];
         let mut independent_layout = self.0.layout(
             layout_context,
-            &initial_containing_block,
+            &(&initial_containing_block).into(),
             dummy_tree_rank,
             &mut absolutely_positioned_fragments,
         );
 
-        let initial_containing_block = DefiniteContainingBlock {
-            size: initial_containing_block_size,
-            style,
-        };
         independent_layout.fragments.par_extend(
             absolutely_positioned_fragments
                 .par_iter()

components/layout_2020/formatting_contexts.rs

@@ -29,6 +29,8 @@ pub(crate) struct IndependentFormattingContext {
 
 pub(crate) struct IndependentLayout {
     pub fragments: Vec<Fragment>,
+
+    /// https://drafts.csswg.org/css2/visudet.html#root-height
     pub content_block_size: Length,
 }
 
@@ -57,31 +59,30 @@ impl IndependentFormattingContext {
         contents: Contents<impl NodeExt<'dom>>,
         content_sizes: ContentSizesRequest,
     ) -> Self {
-        use self::IndependentFormattingContextContents as Contents;
+        match contents.try_into() {
-        let (contents, content_sizes) = match contents.try_into() {
             Ok(non_replaced) => match display_inside {
                 DisplayInside::Flow | DisplayInside::FlowRoot => {
-                    let (bfc, box_content_sizes) = BlockFormattingContext::construct(
+                    let (bfc, content_sizes) = BlockFormattingContext::construct(
                         context,
                         &style,
                         non_replaced,
                         content_sizes,
                     );
-                    (Contents::Flow(bfc), box_content_sizes)
+                    Self {
+                        style,
+                        content_sizes,
+                        contents: IndependentFormattingContextContents::Flow(bfc),
+                    }
                 },
             },
             Err(replaced) => {
-                // The `content_sizes` field is not used by layout code:
+                let content_sizes = content_sizes.compute(|| replaced.inline_content_sizes(&style));
-                (
+                Self {
-                    Contents::Replaced(replaced),
+                    style,
-                    BoxContentSizes::NoneWereRequested,
+                    content_sizes,
-                )
+                    contents: IndependentFormattingContextContents::Replaced(replaced),
+                }
             },
-        };
-        Self {
-            style,
-            contents,
-            content_sizes,
         }
     }
 

components/layout_2020/geom.rs

@@ -2,11 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use crate::ContainingBlock;
 use std::fmt;
 use std::ops::{Add, AddAssign, Sub};
 use style::logical_geometry::{BlockFlowDirection, InlineBaseDirection};
 use style::logical_geometry::{PhysicalCorner, WritingMode};
 use style::values::computed::{Length, LengthOrAuto, LengthPercentage, LengthPercentageOrAuto};
+use style::values::generics::length::MaxSize;
 use style::Zero;
 use style_traits::CSSPixel;
 
@@ -151,6 +153,39 @@ impl flow_relative::Vec2<LengthOrAuto> {
     }
 }
 
+impl flow_relative::Vec2<LengthPercentageOrAuto> {
+    pub fn percentages_relative_to(
+        &self,
+        containing_block: &ContainingBlock,
+    ) -> flow_relative::Vec2<LengthOrAuto> {
+        flow_relative::Vec2 {
+            inline: self
+                .inline
+                .percentage_relative_to(containing_block.inline_size),
+            block: self
+                .block
+                .maybe_percentage_relative_to(containing_block.block_size.non_auto()),
+        }
+    }
+}
+
+impl flow_relative::Vec2<MaxSize<LengthPercentage>> {
+    pub fn percentages_relative_to(
+        &self,
+        containing_block: &ContainingBlock,
+    ) -> flow_relative::Vec2<Option<Length>> {
+        flow_relative::Vec2 {
+            inline: self
+                .inline
+                .to_option()
+                .map(|lp| lp.percentage_relative_to(containing_block.inline_size)),
+            block: self.block.to_option().and_then(|olp| {
+                olp.maybe_percentage_relative_to(containing_block.block_size.non_auto())
+            }),
+        }
+    }
+}
+
 impl flow_relative::Rect<Length> {
     pub fn zero() -> Self {
         Self {

components/layout_2020/lib.rs

@@ -44,6 +44,16 @@ struct DefiniteContainingBlock<'a> {
     style: &'a ComputedValues,
 }
 
+impl<'a> From<&'_ DefiniteContainingBlock<'a>> for ContainingBlock<'a> {
+    fn from(definite: &DefiniteContainingBlock<'a>) -> Self {
+        ContainingBlock {
+            inline_size: definite.size.inline,
+            block_size: LengthOrAuto::LengthPercentage(definite.size.block),
+            style: definite.style,
+        }
+    }
+}
+
 /// https://drafts.csswg.org/css2/visuren.html#relative-positioning
 fn relative_adjustement(
     style: &ComputedValues,

components/layout_2020/positioned.rs

@@ -30,19 +30,24 @@ pub(crate) struct AbsolutelyPositionedFragment<'box_> {
     /// static positions when going up the tree.
     pub(crate) tree_rank: usize,
 
-    pub(crate) inline_start: AbsoluteBoxOffsets<LengthPercentage>,
+    box_offsets: Vec2<AbsoluteBoxOffsets>,
-    inline_size: LengthPercentageOrAuto,
-
-    pub(crate) block_start: AbsoluteBoxOffsets<LengthPercentage>,
-    block_size: LengthPercentageOrAuto,
 }
 
 #[derive(Clone, Copy, Debug)]
-pub(crate) enum AbsoluteBoxOffsets<NonStatic> {
+pub(crate) enum AbsoluteBoxOffsets {
-    StaticStart { start: Length },
+    StaticStart {
-    Start { start: NonStatic },
+        start: Length,
-    End { end: NonStatic },
+    },
-    Both { start: NonStatic, end: NonStatic },
+    Start {
+        start: LengthPercentage,
+    },
+    End {
+        end: LengthPercentage,
+    },
+    Both {
+        start: LengthPercentage,
+        end: LengthPercentage,
+    },
 }
 
 impl AbsolutelyPositionedBox {
@@ -55,7 +60,7 @@ impl AbsolutelyPositionedBox {
         // "Shrink-to-fit" in https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-width
         let content_sizes = ContentSizesRequest::inline_if(
             // If inline-size is non-auto, that value is used without shrink-to-fit
-            style.inline_size_is_auto() &&
+            !style.inline_size_is_length() &&
             // If it is, then the only case where shrink-to-fit is *not* used is
             // if both offsets are non-auto, leaving inline-size as the only variable
             // in the constraint equation.
@@ -77,18 +82,11 @@ impl AbsolutelyPositionedBox {
         initial_start_corner: Vec2<Length>,
         tree_rank: usize,
     ) -> AbsolutelyPositionedFragment {
-        let style = &self.contents.style;
-        let box_offsets = style.box_offsets();
-        let box_size = style.box_size();
-
-        let inline_size = box_size.inline;
-        let block_size = box_size.block;
-
         fn absolute_box_offsets(
             initial_static_start: Length,
             start: LengthPercentageOrAuto,
             end: LengthPercentageOrAuto,
-        ) -> AbsoluteBoxOffsets<LengthPercentage> {
+        ) -> AbsoluteBoxOffsets {
             match (start.non_auto(), end.non_auto()) {
                 (None, None) => AbsoluteBoxOffsets::StaticStart {
                     start: initial_static_start,
@@ -99,24 +97,22 @@ impl AbsolutelyPositionedBox {
             }
         }
 
-        let inline_start = absolute_box_offsets(
+        let box_offsets = self.contents.style.box_offsets();
-            initial_start_corner.inline,
-            box_offsets.inline_start,
-            box_offsets.inline_end,
-        );
-        let block_start = absolute_box_offsets(
-            initial_start_corner.block,
-            box_offsets.block_start,
-            box_offsets.block_end,
-        );
-
         AbsolutelyPositionedFragment {
             absolutely_positioned_box: self,
             tree_rank,
-            inline_start,
+            box_offsets: Vec2 {
-            inline_size,
+                inline: absolute_box_offsets(
-            block_start,
+                    initial_start_corner.inline,
-            block_size,
+                    box_offsets.inline_start,
+                    box_offsets.inline_end,
+                ),
+                block: absolute_box_offsets(
+                    initial_start_corner.block,
+                    box_offsets.block_start,
+                    box_offsets.block_end,
+                ),
+            },
         }
     }
 }
@@ -162,168 +158,90 @@ impl<'a> AbsolutelyPositionedFragment<'a> {
         let cbis = containing_block.size.inline;
         let cbbs = containing_block.size.block;
 
+        let size;
+        let replaced_used_size;
+        match self.absolutely_positioned_box.contents.as_replaced() {
+            Ok(replaced) => {
+                // https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
+                // https://drafts.csswg.org/css2/visudet.html#abs-replaced-height
+                let u = replaced.used_size_as_if_inline_element(&containing_block.into(), style);
+                size = Vec2 {
+                    inline: LengthOrAuto::LengthPercentage(u.inline),
+                    block: LengthOrAuto::LengthPercentage(u.block),
+                };
+                replaced_used_size = Some(u);
+            },
+            Err(_non_replaced) => {
+                let box_size = style.box_size();
+                size = Vec2 {
+                    inline: box_size.inline.percentage_relative_to(cbis),
+                    block: box_size.block.percentage_relative_to(cbbs),
+                };
+                replaced_used_size = None;
+            },
+        }
+
         let padding = style.padding().percentages_relative_to(cbis);
         let border = style.border_width();
         let computed_margin = style.margin().percentages_relative_to(cbis);
         let pb = &padding + &border;
 
-        enum Anchor {
+        let inline_axis = solve_axis(
-            Start(Length),
-            End(Length),
-        }
-
-        fn solve_axis(
-            containing_size: Length,
-            padding_border_sum: Length,
-            computed_margin_start: LengthOrAuto,
-            computed_margin_end: LengthOrAuto,
-            solve_margins: impl FnOnce(Length) -> (Length, Length),
-            box_offsets: AbsoluteBoxOffsets<LengthPercentage>,
-            size: LengthPercentageOrAuto,
-        ) -> (Anchor, LengthOrAuto, Length, Length) {
-            let size = size.percentage_relative_to(containing_size);
-            match box_offsets {
-                AbsoluteBoxOffsets::StaticStart { start } => (
-                    Anchor::Start(start),
-                    size,
-                    computed_margin_start.auto_is(Length::zero),
-                    computed_margin_end.auto_is(Length::zero),
-                ),
-                AbsoluteBoxOffsets::Start { start } => (
-                    Anchor::Start(start.percentage_relative_to(containing_size)),
-                    size,
-                    computed_margin_start.auto_is(Length::zero),
-                    computed_margin_end.auto_is(Length::zero),
-                ),
-                AbsoluteBoxOffsets::End { end } => (
-                    Anchor::End(end.percentage_relative_to(containing_size)),
-                    size,
-                    computed_margin_start.auto_is(Length::zero),
-                    computed_margin_end.auto_is(Length::zero),
-                ),
-                AbsoluteBoxOffsets::Both { start, end } => {
-                    let start = start.percentage_relative_to(containing_size);
-                    let end = end.percentage_relative_to(containing_size);
-
-                    let mut margin_start = computed_margin_start.auto_is(Length::zero);
-                    let mut margin_end = computed_margin_end.auto_is(Length::zero);
-
-                    let size = if let LengthOrAuto::LengthPercentage(size) = size {
-                        let margins = containing_size - start - end - padding_border_sum - size;
-                        match (computed_margin_start, computed_margin_end) {
-                            (LengthOrAuto::Auto, LengthOrAuto::Auto) => {
-                                let (s, e) = solve_margins(margins);
-                                margin_start = s;
-                                margin_end = e;
-                            },
-                            (LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(end)) => {
-                                margin_start = margins - end;
-                            },
-                            (LengthOrAuto::LengthPercentage(start), LengthOrAuto::Auto) => {
-                                margin_end = margins - start;
-                            },
-                            (
-                                LengthOrAuto::LengthPercentage(_),
-                                LengthOrAuto::LengthPercentage(_),
-                            ) => {},
-                        }
-                        size
-                    } else {
-                        // FIXME(nox): What happens if that is negative?
-                        containing_size -
-                            start -
-                            end -
-                            padding_border_sum -
-                            margin_start -
-                            margin_end
-                    };
-                    (
-                        Anchor::Start(start),
-                        LengthOrAuto::LengthPercentage(size),
-                        margin_start,
-                        margin_end,
-                    )
-                },
-            }
-        }
-
-        let (inline_anchor, inline_size, margin_inline_start, margin_inline_end) = solve_axis(
             cbis,
             pb.inline_sum(),
             computed_margin.inline_start,
             computed_margin.inline_end,
-            |margins| {
+            /* avoid_negative_margin_start */ true,
-                if margins.px() >= 0. {
+            self.box_offsets.inline,
-                    (margins / 2., margins / 2.)
+            size.inline,
-                } else {
-                    (Length::zero(), margins)
-                }
-            },
-            self.inline_start,
-            self.inline_size,
         );
 
-        let (block_anchor, block_size, margin_block_start, margin_block_end) = solve_axis(
+        let block_axis = solve_axis(
             cbis,
             pb.block_sum(),
             computed_margin.block_start,
             computed_margin.block_end,
-            |margins| (margins / 2., margins / 2.),
+            /* avoid_negative_margin_start */ false,
-            self.block_start,
+            self.box_offsets.block,
-            self.block_size,
+            size.block,
         );
 
         let margin = Sides {
-            inline_start: margin_inline_start,
+            inline_start: inline_axis.margin_start,
-            inline_end: margin_inline_end,
+            inline_end: inline_axis.margin_end,
-            block_start: margin_block_start,
+            block_start: block_axis.margin_start,
-            block_end: margin_block_end,
+            block_end: block_axis.margin_end,
         };
 
-        let inline_size = inline_size.auto_is(|| {
-            let available_size = match inline_anchor {
-                Anchor::Start(start) => cbis - start - pb.inline_sum() - margin.inline_sum(),
-                Anchor::End(end) => cbis - end - pb.inline_sum() - margin.inline_sum(),
-            };
-
-            if self
-                .absolutely_positioned_box
-                .contents
-                .as_replaced()
-                .is_ok()
-            {
-                // FIXME: implement https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
-                available_size
-            } else {
-                self.absolutely_positioned_box
-                    .contents
-                    .content_sizes
-                    .shrink_to_fit(available_size)
-            }
-        });
-
         let mut absolutely_positioned_fragments = Vec::new();
-        let mut independent_layout = match self.absolutely_positioned_box.contents.as_replaced() {
+        let (size, mut fragments) = match self.absolutely_positioned_box.contents.as_replaced() {
             Ok(replaced) => {
-                // FIXME: implement https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
+                // https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
-                // and https://drafts.csswg.org/css2/visudet.html#abs-replaced-height
+                // https://drafts.csswg.org/css2/visudet.html#abs-replaced-height
-                let block_size = block_size.auto_is(Length::zero);
+                let style = &self.absolutely_positioned_box.contents.style;
-                let fragments = replaced.make_fragments(
+                let size = replaced_used_size.unwrap();
-                    &self.absolutely_positioned_box.contents.style,
+                let fragments = replaced.make_fragments(style, size.clone());
-                    Vec2 {
+                (size, fragments)
-                        inline: inline_size,
-                        block: block_size,
-                    },
-                );
-                crate::formatting_contexts::IndependentLayout {
-                    fragments,
-                    content_block_size: block_size,
-                }
             },
             Err(non_replaced) => {
+                // https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-width
+                // https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-height
+                let inline_size = inline_axis.size.auto_is(|| {
+                    let available_size = match inline_axis.anchor {
+                        Anchor::Start(start) => {
+                            cbis - start - pb.inline_sum() - margin.inline_sum()
+                        },
+                        Anchor::End(end) => cbis - end - pb.inline_sum() - margin.inline_sum(),
+                    };
+                    self.absolutely_positioned_box
+                        .contents
+                        .content_sizes
+                        .shrink_to_fit(available_size)
+                });
+
                 let containing_block_for_children = ContainingBlock {
                     inline_size,
-                    block_size,
+                    block_size: block_axis.size,
                     style,
                 };
                 // https://drafts.csswg.org/css-writing-modes/#orthogonal-flows
@@ -333,24 +251,30 @@ impl<'a> AbsolutelyPositionedFragment<'a> {
                     "Mixed writing modes are not supported yet"
                 );
                 let dummy_tree_rank = 0;
-                non_replaced.layout(
+                let independent_layout = non_replaced.layout(
                     layout_context,
                     &containing_block_for_children,
                     dummy_tree_rank,
                     &mut absolutely_positioned_fragments,
-                )
+                );
+
+                let size = Vec2 {
+                    inline: inline_size,
+                    block: block_axis
+                        .size
+                        .auto_is(|| independent_layout.content_block_size),
+                };
+                (size, independent_layout.fragments)
             },
         };
 
-        let inline_start = match inline_anchor {
+        let inline_start = match inline_axis.anchor {
             Anchor::Start(start) => start + pb.inline_start + margin.inline_start,
-            Anchor::End(end) => cbbs - end - pb.inline_end - margin.inline_end - inline_size,
+            Anchor::End(end) => cbbs - end - pb.inline_end - margin.inline_end - size.inline,
         };
-
+        let block_start = match block_axis.anchor {
-        let block_size = block_size.auto_is(|| independent_layout.content_block_size);
-        let block_start = match block_anchor {
             Anchor::Start(start) => start + pb.block_start + margin.block_start,
-            Anchor::End(end) => cbbs - end - pb.block_end - margin.block_end - block_size,
+            Anchor::End(end) => cbbs - end - pb.block_end - margin.block_end - size.block,
         };
 
         let content_rect = Rect {
@@ -358,16 +282,13 @@ impl<'a> AbsolutelyPositionedFragment<'a> {
                 inline: inline_start,
                 block: block_start,
             },
-            size: Vec2 {
+            size,
-                inline: inline_size,
-                block: block_size,
-            },
         };
 
         AbsolutelyPositionedFragment::in_positioned_containing_block(
             layout_context,
             &absolutely_positioned_fragments,
-            &mut independent_layout.fragments,
+            &mut fragments,
             &content_rect.size,
             &padding,
             style,
@@ -375,7 +296,7 @@ impl<'a> AbsolutelyPositionedFragment<'a> {
 
         Fragment::Box(BoxFragment {
             style: style.clone(),
-            children: independent_layout.fragments,
+            children: fragments,
             content_rect,
             padding,
             border,
@@ -385,6 +306,110 @@ impl<'a> AbsolutelyPositionedFragment<'a> {
     }
 }
 
+enum Anchor {
+    Start(Length),
+    End(Length),
+}
+
+struct AxisResult {
+    anchor: Anchor,
+    size: LengthOrAuto,
+    margin_start: Length,
+    margin_end: Length,
+}
+
+/// This unifies some of the parts in common in:
+///
+/// * https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-width
+/// * https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-height
+///
+/// … and:
+///
+/// * https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
+/// * https://drafts.csswg.org/css2/visudet.html#abs-replaced-height
+///
+/// In the replaced case, `size` is never `Auto`.
+fn solve_axis(
+    containing_size: Length,
+    padding_border_sum: Length,
+    computed_margin_start: LengthOrAuto,
+    computed_margin_end: LengthOrAuto,
+    avoid_negative_margin_start: bool,
+    box_offsets: AbsoluteBoxOffsets,
+    size: LengthOrAuto,
+) -> AxisResult {
+    match box_offsets {
+        AbsoluteBoxOffsets::StaticStart { start } => AxisResult {
+            anchor: Anchor::Start(start),
+            size,
+            margin_start: computed_margin_start.auto_is(Length::zero),
+            margin_end: computed_margin_end.auto_is(Length::zero),
+        },
+        AbsoluteBoxOffsets::Start { start } => AxisResult {
+            anchor: Anchor::Start(start.percentage_relative_to(containing_size)),
+            size,
+            margin_start: computed_margin_start.auto_is(Length::zero),
+            margin_end: computed_margin_end.auto_is(Length::zero),
+        },
+        AbsoluteBoxOffsets::End { end } => AxisResult {
+            anchor: Anchor::End(end.percentage_relative_to(containing_size)),
+            size,
+            margin_start: computed_margin_start.auto_is(Length::zero),
+            margin_end: computed_margin_end.auto_is(Length::zero),
+        },
+        AbsoluteBoxOffsets::Both { start, end } => {
+            let start = start.percentage_relative_to(containing_size);
+            let end = end.percentage_relative_to(containing_size);
+
+            let margin_start;
+            let margin_end;
+            let used_size;
+            if let LengthOrAuto::LengthPercentage(s) = size {
+                used_size = s;
+                let margins = containing_size - start - end - padding_border_sum - s;
+                match (computed_margin_start, computed_margin_end) {
+                    (LengthOrAuto::Auto, LengthOrAuto::Auto) => {
+                        if avoid_negative_margin_start && margins < Length::zero() {
+                            margin_start = Length::zero();
+                            margin_end = margins;
+                        } else {
+                            margin_start = margins / 2.;
+                            margin_end = margins / 2.;
+                        }
+                    },
+                    (LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(end)) => {
+                        margin_start = margins - end;
+                        margin_end = end;
+                    },
+                    (LengthOrAuto::LengthPercentage(start), LengthOrAuto::Auto) => {
+                        margin_start = start;
+                        margin_end = margins - start;
+                    },
+                    (
+                        LengthOrAuto::LengthPercentage(start),
+                        LengthOrAuto::LengthPercentage(end),
+                    ) => {
+                        margin_start = start;
+                        margin_end = end;
+                    },
+                }
+            } else {
+                margin_start = computed_margin_start.auto_is(Length::zero);
+                margin_end = computed_margin_end.auto_is(Length::zero);
+                // FIXME(nox): What happens if that is negative?
+                used_size =
+                    containing_size - start - end - padding_border_sum - margin_start - margin_end
+            };
+            AxisResult {
+                anchor: Anchor::Start(start),
+                size: LengthOrAuto::LengthPercentage(used_size),
+                margin_start,
+                margin_end,
+            }
+        },
+    }
+}
+
 pub(crate) fn adjust_static_positions(
     absolutely_positioned_fragments: &mut [AbsolutelyPositionedFragment],
     child_fragments: &mut [Fragment],
@@ -399,11 +424,11 @@ pub(crate) fn adjust_static_positions(
 
         abspos_fragment.tree_rank = tree_rank_in_parent;
 
-        if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.inline_start {
+        if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.box_offsets.inline {
             *start += child_fragment_rect.start_corner.inline;
         }
 
-        if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.block_start {
+        if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.box_offsets.block {
             *start += child_fragment_rect.start_corner.block;
         }
     }

components/layout_2020/replaced.rs

@@ -4,17 +4,37 @@
 
 use crate::dom_traversal::NodeExt;
 use crate::fragments::{Fragment, ImageFragment};
-use crate::geom::{flow_relative, physical};
+use crate::geom::flow_relative::{Rect, Vec2};
+use crate::geom::physical;
+use crate::sizing::ContentSizes;
+use crate::style_ext::ComputedValuesExt;
+use crate::ContainingBlock;
 use net_traits::image::base::Image;
 use servo_arc::Arc as ServoArc;
 use std::sync::Arc;
 use style::properties::ComputedValues;
-use style::values::computed::Length;
+use style::values::computed::{Length, LengthOrAuto};
+use style::values::CSSFloat;
+use style::Zero;
 
 #[derive(Debug)]
 pub(crate) struct ReplacedContent {
     pub kind: ReplacedContentKind,
-    pub intrinsic_size: physical::Vec2<Length>,
+
+    /// * Raster images always have an instrinsic width and height, with 1 image pixel = 1px.
+    ///   The intrinsic ratio should be based on dividing those.
+    ///   See https://github.com/w3c/csswg-drafts/issues/4572 for the case where either is zero.
+    ///   PNG specifically disallows this but I (SimonSapin) am not sure about other formats.
+    ///
+    /// * Form controls have both intrinsic width and height **but no intrinsic ratio**.
+    ///   See https://github.com/w3c/csswg-drafts/issues/1044 and
+    ///   https://drafts.csswg.org/css-images/#intrinsic-dimensions “In general, […]”
+    ///
+    /// * For SVG, see https://svgwg.org/svg2-draft/coords.html#SizingSVGInCSS
+    ///   and again https://github.com/w3c/csswg-drafts/issues/4572.
+    intrinsic_width: Option<Length>,
+    intrinsic_height: Option<Length>,
+    intrinsic_ratio: Option<CSSFloat>,
 }
 
 #[derive(Debug)]
@@ -24,19 +44,65 @@ pub(crate) enum ReplacedContentKind {
 
 impl ReplacedContent {
     pub fn for_element<'dom>(element: impl NodeExt<'dom>) -> Option<Self> {
-        if let Some((image, intrinsic_size)) = element.as_image() {
+        if let Some((image, intrinsic_size_in_dots)) = element.as_image() {
+            // FIXME: should 'image-resolution' (when implemented) be used *instead* of
+            // `script::dom::htmlimageelement::ImageRequest::current_pixel_density`?
+
+            // https://drafts.csswg.org/css-images-4/#the-image-resolution
+            let dppx = 1.0;
+
+            let width = (intrinsic_size_in_dots.x as CSSFloat) / dppx;
+            let height = (intrinsic_size_in_dots.y as CSSFloat) / dppx;
             return Some(Self {
                 kind: ReplacedContentKind::Image(image),
-                intrinsic_size,
+                intrinsic_width: Some(Length::new(width)),
+                intrinsic_height: Some(Length::new(height)),
+                // FIXME https://github.com/w3c/csswg-drafts/issues/4572
+                intrinsic_ratio: Some(width / height),
             });
         }
         None
     }
 
+    fn flow_relative_intrinsic_size(&self, style: &ComputedValues) -> Vec2<Option<Length>> {
+        let intrinsic_size = physical::Vec2 {
+            x: self.intrinsic_width,
+            y: self.intrinsic_height,
+        };
+        intrinsic_size.size_to_flow_relative(style.writing_mode)
+    }
+
+    fn inline_size_over_block_size_intrinsic_ratio(
+        &self,
+        style: &ComputedValues,
+    ) -> Option<CSSFloat> {
+        self.intrinsic_ratio.map(|width_over_height| {
+            if style.writing_mode.is_vertical() {
+                1. / width_over_height
+            } else {
+                width_over_height
+            }
+        })
+    }
+
+    pub fn inline_content_sizes(&self, style: &ComputedValues) -> ContentSizes {
+        // FIXME: min/max-content of replaced elements is not defined in
+        // https://dbaron.org/css/intrinsic/
+        // This seems sensible?
+        let inline = self
+            .flow_relative_intrinsic_size(style)
+            .inline
+            .unwrap_or(Length::zero());
+        ContentSizes {
+            min_content: inline,
+            max_content: inline,
+        }
+    }
+
     pub fn make_fragments<'a>(
         &'a self,
         style: &ServoArc<ComputedValues>,
-        size: flow_relative::Vec2<Length>,
+        size: Vec2<Length>,
     ) -> Vec<Fragment> {
         match &self.kind {
             ReplacedContentKind::Image(image) => image
@@ -45,8 +111,8 @@ impl ReplacedContent {
                 .map(|image_key| {
                     Fragment::Image(ImageFragment {
                         style: style.clone(),
-                        rect: flow_relative::Rect {
+                        rect: Rect {
-                            start_corner: flow_relative::Vec2::zero(),
+                            start_corner: Vec2::zero(),
                             size,
                         },
                         image_key,
@@ -56,4 +122,214 @@ impl ReplacedContent {
                 .collect(),
         }
     }
+
+    /// https://drafts.csswg.org/css2/visudet.html#inline-replaced-width
+    /// https://drafts.csswg.org/css2/visudet.html#inline-replaced-height
+    ///
+    /// Also used in other cases, for example
+    /// https://drafts.csswg.org/css2/visudet.html#block-replaced-width
+    pub fn used_size_as_if_inline_element(
+        &self,
+        containing_block: &ContainingBlock,
+        style: &ComputedValues,
+    ) -> Vec2<Length> {
+        let mode = style.writing_mode;
+        let intrinsic_size = self.flow_relative_intrinsic_size(style);
+        let intrinsic_ratio = self.inline_size_over_block_size_intrinsic_ratio(style);
+
+        let box_size = style.box_size().percentages_relative_to(containing_block);
+        let min_box_size = style
+            .min_box_size()
+            .percentages_relative_to(containing_block)
+            .auto_is(Length::zero);
+        let max_box_size = style
+            .max_box_size()
+            .percentages_relative_to(containing_block);
+
+        let default_object_size = || {
+            // FIXME:
+            // “If 300px is too wide to fit the device, UAs should use the width of
+            //  the largest rectangle that has a 2:1 ratio and fits the device instead.”
+            // “height of the largest rectangle that has a 2:1 ratio, has a height not greater
+            //  than 150px, and has a width not greater than the device width.”
+            physical::Vec2 {
+                x: Length::new(300.),
+                y: Length::new(150.),
+            }
+            .size_to_flow_relative(mode)
+        };
+        let clamp = |inline_size: Length, block_size: Length| Vec2 {
+            inline: inline_size.clamp_between_extremums(min_box_size.inline, max_box_size.inline),
+            block: block_size.clamp_between_extremums(min_box_size.block, max_box_size.block),
+        };
+        // https://drafts.csswg.org/css2/visudet.html#min-max-widths
+        // https://drafts.csswg.org/css2/visudet.html#min-max-heights
+        match (box_size.inline, box_size.block) {
+            (LengthOrAuto::LengthPercentage(inline), LengthOrAuto::LengthPercentage(block)) => {
+                clamp(inline, block)
+            },
+            (LengthOrAuto::LengthPercentage(inline), LengthOrAuto::Auto) => {
+                let block = if let Some(i_over_b) = intrinsic_ratio {
+                    inline / i_over_b
+                } else if let Some(block) = intrinsic_size.block {
+                    block
+                } else {
+                    default_object_size().block
+                };
+                clamp(inline, block)
+            },
+            (LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(block)) => {
+                let inline = if let Some(i_over_b) = intrinsic_ratio {
+                    block * i_over_b
+                } else if let Some(inline) = intrinsic_size.inline {
+                    inline
+                } else {
+                    default_object_size().inline
+                };
+                clamp(inline, block)
+            },
+            (LengthOrAuto::Auto, LengthOrAuto::Auto) => {
+                let inline_size =
+                    match (intrinsic_size.inline, intrinsic_size.block, intrinsic_ratio) {
+                        (Some(inline), _, _) => inline,
+                        (None, Some(block), Some(i_over_b)) => {
+                            // “used height” in CSS 2 is always gonna be the intrinsic one,
+                            // since it is available.
+                            block * i_over_b
+                        },
+                        // FIXME
+                        //
+                        // “If 'height' and 'width' both have computed values of 'auto'
+                        // and the element has an intrinsic ratio but no intrinsic height or width,
+                        // […]”
+                        //
+                        // In this `match` expression this would be an additional arm here:
+                        //
+                        // ```
+                        // (Vec2 { inline: None, block: None }, Some(_)) => {…}
+                        // ```
+                        //
+                        // “[…] then the used value of 'width' is undefined in CSS 2.
+                        // However, it is suggested that, if the containing block's width
+                        // does not itself depend on the replaced element's width,
+                        // then the used value of 'width' is calculated from the constraint
+                        // equation used for block-level, non-replaced elements in normal flow.”
+                        _ => default_object_size().inline,
+                    };
+                let block_size = if let Some(block) = intrinsic_size.block {
+                    block
+                } else if let Some(i_over_b) = intrinsic_ratio {
+                    // “used width” in CSS 2 is what we just computed above
+                    inline_size / i_over_b
+                } else {
+                    default_object_size().block
+                };
+
+                let i_over_b = if let Some(i_over_b) = intrinsic_ratio {
+                    i_over_b
+                } else {
+                    return clamp(inline_size, block_size);
+                };
+
+                // https://drafts.csswg.org/css2/visudet.html#min-max-widths
+                // “However, for replaced elements with an intrinsic ratio and both
+                //  'width' and 'height' specified as 'auto', the algorithm is as follows”
+                enum Violation {
+                    None,
+                    Below(Length),
+                    Above(Length),
+                }
+                let violation = |size, min_size, mut max_size: Option<Length>| {
+                    if let Some(max) = max_size.as_mut() {
+                        max.max_assign(min_size);
+                    }
+                    if size < min_size {
+                        return Violation::Below(min_size);
+                    }
+                    match max_size {
+                        Some(max_size) if size > max_size => Violation::Above(max_size),
+                        _ => Violation::None,
+                    }
+                };
+                match (
+                    violation(inline_size, min_box_size.inline, max_box_size.inline),
+                    violation(block_size, min_box_size.block, max_box_size.block),
+                ) {
+                    // Row 1.
+                    (Violation::None, Violation::None) => Vec2 {
+                        inline: inline_size,
+                        block: block_size,
+                    },
+                    // Row 2.
+                    (Violation::Above(max_inline_size), Violation::None) => Vec2 {
+                        inline: max_inline_size,
+                        block: (max_inline_size / i_over_b).max(min_box_size.block),
+                    },
+                    // Row 3.
+                    (Violation::Below(min_inline_size), Violation::None) => Vec2 {
+                        inline: min_inline_size,
+                        block: (min_inline_size / i_over_b).clamp_below_max(max_box_size.block),
+                    },
+                    // Row 4.
+                    (Violation::None, Violation::Above(max_block_size)) => Vec2 {
+                        inline: (max_block_size * i_over_b).max(min_box_size.inline),
+                        block: max_block_size,
+                    },
+                    // Row 5.
+                    (Violation::None, Violation::Below(min_block_size)) => Vec2 {
+                        inline: (min_block_size * i_over_b).clamp_below_max(max_box_size.inline),
+                        block: min_block_size,
+                    },
+                    // Rows 6-7.
+                    (Violation::Above(max_inline_size), Violation::Above(max_block_size)) => {
+                        if max_inline_size.px() / inline_size.px() <=
+                            max_block_size.px() / block_size.px()
+                        {
+                            // Row 6.
+                            Vec2 {
+                                inline: max_inline_size,
+                                block: (max_inline_size / i_over_b).max(min_box_size.block),
+                            }
+                        } else {
+                            // Row 7.
+                            Vec2 {
+                                inline: (max_block_size * i_over_b).max(min_box_size.inline),
+                                block: max_block_size,
+                            }
+                        }
+                    },
+                    // Rows 8-9.
+                    (Violation::Below(min_inline_size), Violation::Below(min_block_size)) => {
+                        if min_inline_size.px() / inline_size.px() <=
+                            min_block_size.px() / block_size.px()
+                        {
+                            // Row 8.
+                            Vec2 {
+                                inline: (min_block_size * i_over_b)
+                                    .clamp_below_max(max_box_size.inline),
+                                block: min_block_size,
+                            }
+                        } else {
+                            // Row 9.
+                            Vec2 {
+                                inline: min_inline_size,
+                                block: (min_inline_size / i_over_b)
+                                    .clamp_below_max(max_box_size.block),
+                            }
+                        }
+                    },
+                    // Row 10.
+                    (Violation::Below(min_inline_size), Violation::Above(max_block_size)) => Vec2 {
+                        inline: min_inline_size,
+                        block: max_block_size,
+                    },
+                    // Row 11.
+                    (Violation::Above(max_inline_size), Violation::Below(min_block_size)) => Vec2 {
+                        inline: max_inline_size,
+                        block: min_block_size,
+                    },
+                }
+            },
+        }
+    }
 }

components/layout_2020/sizing.rs

@@ -107,17 +107,37 @@ impl BoxContentSizes {
         &self,
         style: &ComputedValues,
     ) -> (ContentSizes, Percentage) {
-        // FIXME: account for 'min-width', 'max-width', 'box-sizing'
+        // FIXME: account for 'box-sizing'
-
         let inline_size = style.box_size().inline;
+        let min_inline_size = style
+            .min_box_size()
+            .inline
+            .percentage_relative_to(Length::zero())
+            .auto_is(Length::zero);
+        let max_inline_size = style
+            .max_box_size()
+            .inline
+            .to_option()
+            .and_then(|lp| lp.as_length());
+        let clamp = |l: Length| l.clamp_between_extremums(min_inline_size, max_inline_size);
+
         // Percentages for 'width' are treated as 'auto'
         let inline_size = inline_size.map(|lp| lp.as_length());
         // The (inner) min/max-content are only used for 'auto'
         let mut outer = match inline_size.non_auto().flatten() {
-            None => self.expect_inline().clone(),
+            None => {
-            Some(length) => ContentSizes {
+                let inner = self.expect_inline().clone();
-                min_content: length,
+                ContentSizes {
-                max_content: length,
+                    min_content: clamp(inner.min_content),
+                    max_content: clamp(inner.max_content),
+                }
+            },
+            Some(length) => {
+                let length = clamp(length);
+                ContentSizes {
+                    min_content: length,
+                    max_content: length,
+                }
             },
         };
 

components/layout_2020/style_ext.rs

@@ -40,7 +40,7 @@ pub(crate) enum DisplayInside {
 }
 
 pub(crate) trait ComputedValuesExt {
-    fn inline_size_is_auto(&self) -> bool;
+    fn inline_size_is_length(&self) -> bool;
     fn inline_box_offsets_are_both_non_auto(&self) -> bool;
     fn box_offsets(&self) -> flow_relative::Sides<LengthPercentageOrAuto>;
     fn box_size(&self) -> flow_relative::Vec2<LengthPercentageOrAuto>;
@@ -52,14 +52,14 @@ pub(crate) trait ComputedValuesExt {
 }
 
 impl ComputedValuesExt for ComputedValues {
-    fn inline_size_is_auto(&self) -> bool {
+    fn inline_size_is_length(&self) -> bool {
         let position = self.get_position();
         let size = if self.writing_mode.is_horizontal() {
             position.width
         } else {
             position.height
         };
-        size == Size::Auto
+        matches!(size, Size::LengthPercentage(lp) if lp.0.as_length().is_some())
     }
 
     fn inline_box_offsets_are_both_non_auto(&self) -> bool {

components/style/values/computed/length.rs

@@ -657,14 +657,14 @@ impl CSSPixelLength {
 
     /// Return the containing pixel value.
     #[inline]
-    pub fn px(&self) -> CSSFloat {
+    pub fn px(self) -> CSSFloat {
         self.0
     }
 
     /// Return the length with app_unit i32 type.
     #[inline]
-    pub fn to_i32_au(&self) -> i32 {
+    pub fn to_i32_au(self) -> i32 {
-        Au::from(*self).0
+        Au::from(self).0
     }
 
     /// Return the absolute value of this length.
@@ -692,9 +692,29 @@ impl CSSPixelLength {
     }
 
     /// Sets `self` to the maximum between `self` and `other`.
+    #[inline]
     pub fn max_assign(&mut self, other: Self) {
         *self = self.max(other);
     }
+
+    /// Clamp the value to a lower bound and an optional upper bound.
+    ///
+    /// Can be used for example with `min-width` and `max-width`.
+    #[inline]
+    pub fn clamp_between_extremums(self, min_size: Self, max_size: Option<Self>) -> Self {
+        self.clamp_below_max(max_size).max(min_size)
+    }
+
+    /// Clamp the value to an optional upper bound.
+    ///
+    /// Can be used for example with `max-width`.
+    #[inline]
+    pub fn clamp_below_max(self, max_size: Option<Self>) -> Self {
+        match max_size {
+            None => self,
+            Some(max_size) => self.min(max_size),
+        }
+    }
 }
 
 impl Zero for CSSPixelLength {

components/style/values/generics/length.rs

@@ -207,6 +207,15 @@ impl<LengthPercentage> MaxSize<LengthPercentage> {
     pub fn none() -> Self {
         MaxSize::None
     }
+
+    /// Convert
+    #[cfg(not(feature = "gecko"))]
+    pub fn to_option(self) -> Option<LengthPercentage> {
+        match self {
+            Self::LengthPercentage(lp) => Some(lp),
+            Self::None => None,
+        }
+    }
 }
 
 /// A generic `<length>` | `<number>` value for the `-moz-tab-size` property.

tests/wpt/metadata-layout-2020/css/CSS2/box-display/containing-block-008.xht.ini

@@ -0,0 +1,2 @@
+[containing-block-008.xht]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/box-display/containing-block-009.xht.ini

@@ -0,0 +1,2 @@
+[containing-block-009.xht]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/box-display/containing-block-010.xht.ini

@@ -0,0 +1,2 @@
+[containing-block-010.xht]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/box-display/containing-block-027.xht.ini

@@ -0,0 +1,2 @@
+[containing-block-027.xht]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/box-display/containing-block-028.xht.ini

@@ -0,0 +1,2 @@
+[containing-block-028.xht]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/box-display/display-change-001.xht.ini

@@ -1,2 +0,0 @@
-[display-change-001.xht]
-  expected: FAIL