Make `for_maybe_position_relative` take care of relative adjustment.

components/layout_2020/flow/inline.rs

@@ -9,10 +9,10 @@ use crate::formatting_contexts::IndependentFormattingContext;
 use crate::fragments::CollapsedBlockMargins;
 use crate::fragments::{AnonymousFragment, BoxFragment, Fragment, TextFragment};
 use crate::geom::flow_relative::{Rect, Sides, Vec2};
-use crate::positioned::{AbsolutelyPositionedBox, PositioningContext};
+use crate::positioned::{relative_adjustement, AbsolutelyPositionedBox, PositioningContext};
 use crate::sizing::ContentSizes;
 use crate::style_ext::{ComputedValuesExt, Display, DisplayGeneratingBox, DisplayOutside};
-use crate::{relative_adjustement, ContainingBlock};
+use crate::ContainingBlock;
 use app_units::Au;
 use gfx::text::text_run::GlyphRun;
 use servo_arc::Arc;
@@ -367,11 +367,9 @@ impl InlineBox {
             block: padding.block_start + border.block_start + margin.block_start,
             inline: ifc.inline_position - ifc.current_nesting_level.inline_start,
         };
-        start_corner += &relative_adjustement(
-            &style,
-            ifc.containing_block.inline_size,
-            ifc.containing_block.block_size,
-        );
+        if style.clone_position().is_relative() {
+            start_corner += &relative_adjustement(&style, ifc.containing_block)
+        }
         PartialInlineBoxFragment {
             style,
             start_corner,
@@ -457,11 +455,9 @@ fn layout_atomic<'box_tree>(
         block: pbm.block_start,
         inline: ifc.inline_position - ifc.current_nesting_level.inline_start,
     };
-    start_corner += &relative_adjustement(
-        &atomic.style,
-        ifc.containing_block.inline_size,
-        ifc.containing_block.block_size,
-    );
+    if atomic.style.clone_position().is_relative() {
+        start_corner += &relative_adjustement(&atomic.style, ifc.containing_block)
+    }
 
     let fragment = match atomic.as_replaced() {
         Ok(replaced) => {

components/layout_2020/flow/mod.rs

@@ -14,7 +14,7 @@ use crate::geom::flow_relative::{Rect, Sides, Vec2};
 use crate::positioned::{AbsolutelyPositionedBox, PositioningContext};
 use crate::replaced::ReplacedContent;
 use crate::style_ext::ComputedValuesExt;
-use crate::{relative_adjustement, ContainingBlock};
+use crate::ContainingBlock;
 use rayon::iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator};
 use rayon_croissant::ParallelIteratorExt;
 use servo_arc::Arc;
@@ -271,6 +271,7 @@ impl BlockLevelBox {
             BlockLevelBox::SameFormattingContextBlock { style, contents } => {
                 Fragment::Box(positioning_context.for_maybe_position_relative(
                     layout_context,
+                    containing_block,
                     style,
                     |positioning_context| {
                         layout_in_flow_non_replaced_block_level(
@@ -288,6 +289,7 @@ impl BlockLevelBox {
             BlockLevelBox::Independent(contents) => {
                 Fragment::Box(positioning_context.for_maybe_position_relative(
                     layout_context,
+                    containing_block,
                     &contents.style,
                     |positioning_context| match contents.as_replaced() {
                         Ok(replaced) => layout_in_flow_replaced_block_level(
@@ -470,14 +472,13 @@ fn layout_in_flow_non_replaced_block_level<'a>(
             content_block_size = independent_layout.content_block_size;
         },
     };
-    let relative_adjustement = relative_adjustement(style, inline_size, block_size);
     let block_size = block_size.auto_is(|| {
         content_block_size.clamp_between_extremums(min_box_size.block, max_box_size.block)
     });
     let content_rect = Rect {
         start_corner: Vec2 {
-            block: pb.block_start + relative_adjustement.block,
-            inline: pb.inline_start + relative_adjustement.inline + margin.inline_start,
+            block: pb.block_start,
+            inline: pb.inline_start,
         },
         size: Vec2 {
             block: block_size,
@@ -525,15 +526,10 @@ fn layout_in_flow_replaced_block_level<'a>(
         block_end: computed_margin.block_end.auto_is(Length::zero),
     };
     let fragments = replaced.make_fragments(style, size.clone());
-    let relative_adjustement = relative_adjustement(
-        style,
-        size.inline,
-        LengthOrAuto::LengthPercentage(size.block),
-    );
     let content_rect = Rect {
         start_corner: Vec2 {
-            block: pb.block_start + relative_adjustement.block,
-            inline: pb.inline_start + relative_adjustement.inline + margin.inline_start,
+            block: pb.block_start,
+            inline: pb.inline_start + margin.inline_start,
         },
         size,
     };

components/layout_2020/lib.rs

@@ -27,11 +27,8 @@ pub mod wrapper;
 pub use flow::{BoxTreeRoot, FragmentTreeRoot};
 
 use crate::geom::flow_relative::Vec2;
-use crate::style_ext::ComputedValuesExt;
-use style::computed_values::position::T as Position;
 use style::properties::ComputedValues;
 use style::values::computed::{Length, LengthOrAuto};
-use style::Zero;
 
 struct ContainingBlock<'a> {
     inline_size: Length,
@@ -53,30 +50,3 @@ impl<'a> From<&'_ DefiniteContainingBlock<'a>> for ContainingBlock<'a> {
         }
     }
 }
-
-/// https://drafts.csswg.org/css2/visuren.html#relative-positioning
-fn relative_adjustement(
-    style: &ComputedValues,
-    inline_size: Length,
-    block_size: LengthOrAuto,
-) -> Vec2<Length> {
-    if style.get_box().position != Position::Relative {
-        return Vec2::zero();
-    }
-    fn adjust(start: LengthOrAuto, end: LengthOrAuto) -> Length {
-        match (start, end) {
-            (LengthOrAuto::Auto, LengthOrAuto::Auto) => Length::zero(),
-            (LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(end)) => -end,
-            (LengthOrAuto::LengthPercentage(start), _) => start,
-        }
-    }
-    let block_size = block_size.auto_is(Length::zero);
-    let box_offsets = style.box_offsets().map_inline_and_block_axes(
-        |v| v.percentage_relative_to(inline_size),
-        |v| v.percentage_relative_to(block_size),
-    );
-    Vec2 {
-        inline: adjust(box_offsets.inline_start, box_offsets.inline_end),
-        block: adjust(box_offsets.block_start, box_offsets.block_end),
-    }
-}

components/layout_2020/positioned.rs

@@ -150,11 +150,17 @@ impl<'box_tree> PositioningContext<'box_tree> {
     pub(crate) fn for_maybe_position_relative(
         &mut self,
         layout_context: &LayoutContext,
+        containing_block: &ContainingBlock,
         style: &ComputedValues,
         f: impl FnOnce(&mut Self) -> BoxFragment,
     ) -> BoxFragment {
         if style.clone_position() == Position::Relative {
-            Self::for_positioned(layout_context, &mut self.for_initial_containing_block, f)
+            let mut fragment =
+                // Establing a containing block for absolutely positioned descendants
+                Self::for_positioned(layout_context, &mut self.for_initial_containing_block, f);
+
+            fragment.content_rect.start_corner += &relative_adjustement(style, containing_block);
+            fragment
         } else {
             f(self)
         }
@@ -610,3 +616,27 @@ fn vec_append_owned<T>(a: &mut Vec<T>, mut b: Vec<T>) {
         a.append(&mut b)
     }
 }
+
+/// https://drafts.csswg.org/css2/visuren.html#relative-positioning
+pub(crate) fn relative_adjustement(
+    style: &ComputedValues,
+    containing_block: &ContainingBlock,
+) -> Vec2<Length> {
+    let cbis = containing_block.inline_size;
+    let cbbs = containing_block.block_size.auto_is(Length::zero);
+    let box_offsets = style.box_offsets().map_inline_and_block_axes(
+        |v| v.percentage_relative_to(cbis),
+        |v| v.percentage_relative_to(cbbs),
+    );
+    fn adjust(start: LengthOrAuto, end: LengthOrAuto) -> Length {
+        match (start, end) {
+            (LengthOrAuto::Auto, LengthOrAuto::Auto) => Length::zero(),
+            (LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(end)) => -end,
+            (LengthOrAuto::LengthPercentage(start), _) => start,
+        }
+    }
+    Vec2 {
+        inline: adjust(box_offsets.inline_start, box_offsets.inline_end),
+        block: adjust(box_offsets.block_start, box_offsets.block_end),
+    }
+}

components/style/properties/longhands/box.mako.rs

@@ -55,6 +55,9 @@ impl computed_value::T {
     pub fn is_absolutely_positioned(self) -> bool {
         matches!(self, Self::Absolute | Self::Fixed)
     }
+    pub fn is_relative(self) -> bool {
+        self == Self::Relative
+    }
 }
 </%helpers:single_keyword>