Implement absolute positioning

Shrink-to-fit size is missing, absolute positioning in inline formatting contexts is missing. There are probably off-by-some-amount-of-pixels bugs lying around.
SimonSapin · Apr 3, 2019 · cea21bb · cea21bb
1 parent 6ddce73
commit cea21bb
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Showing 11 changed files with 537 additions and 32 deletions.
diff --git a/tests/reftests/abspos-ref.html b/tests/reftests/abspos-ref.html
@@ -0,0 +1,6 @@
+<!doctype html>
+<body style="margin:0px">
+<div style="background-color: green; padding-left: 70px; padding-top: 20px; width: 130px; height: 80px">
+    <div style="background-color: red; width: 50px; height: 30px"></div>
+</div>
+</body>
diff --git a/tests/reftests/abspos.html b/tests/reftests/abspos.html
@@ -0,0 +1,7 @@
+<!doctype html>
+<link rel=match href="abspos-ref.html">
+<body style="margin:0px">
+<div style="background-color: green; width: 200px; height: 100px">
+    <div style="background-color: red; position: absolute; top: 20px; left: 70px; width: 50px; height: 30px"></div>
+</div>
+</body>
diff --git a/victor/src/geom.rs b/victor/src/geom.rs
@@ -60,6 +60,7 @@ where
         }
     }
 }
+
 impl<T: Clone> physical::Vec2<T> {
     pub fn size_to_flow_relative(&self, mode: (WritingMode, Direction)) -> flow_relative::Vec2<T> {
         // https://drafts.csswg.org/css-writing-modes/#logical-to-physical
@@ -75,6 +76,20 @@ impl<T: Clone> physical::Vec2<T> {
     }
 }
 
+impl<T> Add<&'_ flow_relative::Vec2<T>> for &'_ flow_relative::Vec2<T>
+where
+    T: Add<Output = T> + Copy,
+{
+    type Output = flow_relative::Vec2<T>;
+
+    fn add(self, other: &'_ flow_relative::Vec2<T>) -> Self::Output {
+        flow_relative::Vec2 {
+            inline: self.inline + other.inline,
+            block: self.block + other.block,
+        }
+    }
+}
+
 impl<T: Clone> flow_relative::Vec2<T> {
     pub fn size_to_physical(&self, mode: (WritingMode, Direction)) -> physical::Vec2<T> {
         // https://drafts.csswg.org/css-writing-modes/#logical-to-physical

diff --git a/victor/src/layout/boxes/generation.rs b/victor/src/layout/boxes/generation.rs
@@ -2,7 +2,7 @@ use super::*;
 use crate::dom;
 use crate::fonts::BITSTREAM_VERA_SANS;
 use crate::layout::Take;
-use crate::style::values::{Display, DisplayInside, DisplayOutside};
+use crate::style::values::{Display, DisplayInside, DisplayOutside, Position};
 use crate::style::{style_for_element, StyleSet, StyleSetBuilder};
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 
@@ -38,6 +38,10 @@ enum IntermediateBlockLevelBox {
         style: Arc<ComputedValues>,
         contents: IntermediateBlockContainer,
     },
+    AbsolutelyPositionedBox {
+        style: Arc<ComputedValues>,
+        element: dom::NodeId,
+    },
 }
 
 /// A block container that may still have to be constructed.
@@ -216,16 +220,28 @@ impl<'a> BlockContainerBuilder<'a> {
             descendant,
             parent_style.map(|style| &**style),
         );
-        match descendant_style.box_.display {
-            Display::None => self.move_to_next_sibling(descendant),
-            Display::Other {
-                outside: DisplayOutside::Inline,
-                inside: DisplayInside::Flow,
-            } => self.handle_inline_level_element(descendant, descendant_style),
-            Display::Other {
-                outside: DisplayOutside::Block,
-                inside: DisplayInside::Flow,
-            } => self.handle_block_level_element(descendant, descendant_style),
+        match (
+            descendant_style.box_.display,
+            descendant_style.box_.position,
+        ) {
+            (Display::None, _) => self.move_to_next_sibling(descendant),
+            (_, Position::Absolute) => {
+                self.handle_absolutely_positioned_element(descendant, descendant_style)
+            }
+            (
+                Display::Other {
+                    outside: DisplayOutside::Inline,
+                    inside: DisplayInside::Flow,
+                },
+                _,
+            ) => self.handle_inline_level_element(descendant, descendant_style),
+            (
+                Display::Other {
+                    outside: DisplayOutside::Block,
+                    inside: DisplayInside::Flow,
+                },
+                _,
+            ) => self.handle_block_level_element(descendant, descendant_style),
         }
     }
 
@@ -318,6 +334,29 @@ impl<'a> BlockContainerBuilder<'a> {
         self.move_to_next_sibling(descendant)
     }
 
+    fn handle_absolutely_positioned_element(
+        &mut self,
+        descendant: dom::NodeId,
+        descendant_style: Arc<ComputedValues>,
+    ) -> Option<dom::NodeId> {
+        if self
+            .ongoing_inline_formatting_context
+            .inline_level_boxes
+            .is_empty()
+            && self.ongoing_inline_level_box_stack.is_empty()
+        {
+            self.block_level_boxes
+                .push(IntermediateBlockLevelBox::AbsolutelyPositionedBox {
+                    style: descendant_style,
+                    element: descendant,
+                })
+        } else {
+            // FIXME(nox): Handle absolutely-positioned elements in
+            // inline boxes.
+        }
+        self.move_to_next_sibling(descendant)
+    }
+
     fn move_to_next_sibling(&mut self, descendant: dom::NodeId) -> Option<dom::NodeId> {
         let mut descendant_node = &self.context.document[descendant];
         if let Some(next_sibling) = descendant_node.next_sibling {
@@ -411,6 +450,16 @@ impl IntermediateBlockLevelBox {
                     style,
                 }
             }
+            IntermediateBlockLevelBox::AbsolutelyPositionedBox { style, element } => {
+                BlockLevelBox::AbsolutelyPositionedBox {
+                    contents: BlockFormattingContext(BlockContainerBuilder::build(
+                        context,
+                        element,
+                        Some(&style),
+                    )),
+                    style: style,
+                }
+            }
         }
     }
 }

diff --git a/victor/src/layout/boxes/mod.rs b/victor/src/layout/boxes/mod.rs
@@ -31,6 +31,10 @@ pub(super) enum BlockLevelBox {
         style: Arc<ComputedValues>,
         contents: BlockContainer,
     },
+    AbsolutelyPositionedBox {
+        style: Arc<ComputedValues>,
+        contents: BlockFormattingContext,
+    },
     // Other {
     //     style: Arc<ComputedValues>,
     //     contents: FormattingContext,

diff --git a/victor/src/layout/fragments/mod.rs b/victor/src/layout/fragments/mod.rs
@@ -1,4 +1,4 @@
-use crate::geom::flow_relative::{Rect, Sides};
+use crate::geom::flow_relative::{Rect, Sides, Vec2};
 use crate::geom::Length;
 use crate::style::ComputedValues;
 use crate::text::ShapedSegment;
@@ -30,6 +30,30 @@ pub(crate) struct TextFragment {
 }
 
 impl BoxFragment {
+    pub fn zero_sized(style: Arc<ComputedValues>) -> Self {
+        let zero_vec = Vec2 {
+            inline: Length::zero(),
+            block: Length::zero(),
+        };
+        let zero_sides = Sides {
+            inline_start: Length::zero(),
+            inline_end: Length::zero(),
+            block_start: Length::zero(),
+            block_end: Length::zero(),
+        };
+        Self {
+            style,
+            children: vec![],
+            content_rect: Rect {
+                start_corner: zero_vec.clone(),
+                size: zero_vec,
+            },
+            padding: zero_sides.clone(),
+            border: zero_sides.clone(),
+            margin: zero_sides,
+        }
+    }
+
     pub fn border_rect(&self) -> Rect<Length> {
         self.content_rect
             .inflate(&self.padding)