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layout_2020: Paint hoisted positioned fragments in tree order

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Instead of painting hoisted position fragments in the order to which
they are hoisted, paint them in tree order and properly incorporate them
into the stacking context.

We do this by creating a placeholder fragment in the original tree position
of hoisted fragments. The ghost fragment contains an atomic id which
links back to the hoisted fragment in the containing block.

While building the stacking context, we keep track of containing blocks
and their children. When encountering a placeholder fragment we look at
the containing block's hoisted children in order to properly paint the
hoisted fragment.

One notable design modification in this change is that hoisted fragments
no longer need an AnonymousFragment as their parent. Instead they are
now direct children of the fragment that establishes their containing block.
This commit is contained in:
Martin Robinson 2020-03-02 08:43:43 +01:00
parent e3c91f7c49
commit c3b1c92ac1
41 changed files with 382 additions and 159 deletions
Download patch file Download diff file Expand all files Collapse all files

21
components/layout_2020/flow/inline.rs
View file

@ -6,8 +6,10 @@ use crate::context::LayoutContext;
use crate::flow::float::FloatBox;
use crate::flow::FlowLayout;
use crate::formatting_contexts::IndependentFormattingContext;
use crate::fragments::CollapsedBlockMargins;
use crate::fragments::{AnonymousFragment, BoxFragment, DebugId, Fragment, TextFragment};
use crate::fragments::{
AbsoluteOrFixedPositionedFragment, AnonymousFragment, BoxFragment, CollapsedBlockMargins,
DebugId, Fragment, TextFragment,
};
use crate::geom::flow_relative::{Rect, Sides, Vec2};
use crate::positioned::{relative_adjustement, AbsolutelyPositionedBox, PositioningContext};
use crate::sizing::ContentSizes;
@ -254,8 +256,14 @@ impl InlineFormattingContext {
panic!("display:none does not generate an abspos box")
},
};
ifc.positioning_context
.push(box_.to_hoisted(initial_start_corner, tree_rank));
let hoisted_fragment = box_.to_hoisted(initial_start_corner, tree_rank);
let hoisted_fragment_id = hoisted_fragment.fragment_id;
ifc.positioning_context.push(hoisted_fragment);
ifc.lines
.fragments
.push(Fragment::AbsoluteOrFixedPositioned(
AbsoluteOrFixedPositionedFragment(hoisted_fragment_id),
));
},
InlineLevelBox::OutOfFlowFloatBox(_box_) => {
// TODO
@ -333,7 +341,7 @@ impl Lines {
};
if move_by > Length::zero() {
for fragment in &mut line_contents {
fragment.position_mut().inline += move_by;
fragment.offset_inline(&move_by);
}
}
let start_corner = Vec2 {
@ -426,6 +434,7 @@ impl<'box_tree> PartialInlineBoxFragment<'box_tree> {
self.border.clone(),
self.margin.clone(),
CollapsedBlockMargins::zero(),
None, // hoisted_fragment_id
);
let last_fragment = self.last_box_tree_fragment && !at_line_break;
if last_fragment {
@ -488,6 +497,7 @@ fn layout_atomic<'box_tree>(
border,
margin,
CollapsedBlockMargins::zero(),
None, // hoisted_fragment_id
)
},
Err(non_replaced) => {
@ -563,6 +573,7 @@ fn layout_atomic<'box_tree>(
border,
margin,
CollapsedBlockMargins::zero(),
None, // hoisted_fragment_id
)
},
};

21
components/layout_2020/flow/mod.rs
View file

@ -8,7 +8,7 @@ use crate::context::LayoutContext;
use crate::flow::float::{FloatBox, FloatContext};
use crate::flow::inline::InlineFormattingContext;
use crate::formatting_contexts::{IndependentFormattingContext, IndependentLayout, NonReplacedIFC};
use crate::fragments::{AnonymousFragment, BoxFragment};
use crate::fragments::{AbsoluteOrFixedPositionedFragment, AnonymousFragment, BoxFragment};
use crate::fragments::{CollapsedBlockMargins, CollapsedMargin, Fragment};
use crate::geom::flow_relative::{Rect, Sides, Vec2};
use crate::positioned::{AbsolutelyPositionedBox, PositioningContext};
@ -176,14 +176,7 @@ fn layout_block_level_children<'a>(
placement_state.current_margin.solve() + fragment_block_size;
placement_state.current_margin = fragment_block_margins.end;
},
Fragment::Anonymous(fragment) => {
// FIXME(nox): Margin collapsing for hypothetical boxes of
// abspos elements is probably wrong.
assert!(fragment.children.is_empty());
assert_eq!(fragment.rect.size.block, Length::zero());
fragment.rect.start_corner.block +=
placement_state.current_block_direction_position;
},
Fragment::Anonymous(_) | Fragment::AbsoluteOrFixedPositioned(_) => {},
_ => unreachable!(),
}
}
@ -321,9 +314,11 @@ impl BlockLevelBox {
))
},
BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(box_) => {
positioning_context.push(box_.to_hoisted(Vec2::zero(), tree_rank));
Fragment::Anonymous(AnonymousFragment::no_op(
containing_block.style.writing_mode,
let hoisted_fragment = box_.to_hoisted(Vec2::zero(), tree_rank);
let hoisted_fragment_id = hoisted_fragment.fragment_id.clone();
positioning_context.push(hoisted_fragment);
Fragment::AbsoluteOrFixedPositioned(AbsoluteOrFixedPositionedFragment(
hoisted_fragment_id,
))
},
BlockLevelBox::OutOfFlowFloatBox(_box_) => {
@ -505,6 +500,7 @@ fn layout_in_flow_non_replaced_block_level<'a>(
border,
margin,
block_margins_collapsed_with_children,
None, // hoisted_fragment_id
)
}
@ -556,6 +552,7 @@ fn layout_in_flow_replaced_block_level<'a>(
border,
margin,
block_margins_collapsed_with_children,
None, // hoisted_fragment_id
)
}

33
components/layout_2020/flow/root.rs
View file

@ -3,7 +3,10 @@
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use crate::context::LayoutContext;
use crate::display_list::stacking_context::StackingContext;
use crate::display_list::stacking_context::{
ContainingBlock, ContainingBlockInfo, StackingContext, StackingContextBuildMode,
StackingContextBuilder,
};
use crate::dom_traversal::{Contents, NodeExt};
use crate::flow::construct::ContainsFloats;
use crate::flow::float::FloatBox;
@ -186,12 +189,26 @@ impl BoxTreeRoot {
impl FragmentTreeRoot {
pub fn build_display_list(&self, builder: &mut crate::display_list::DisplayListBuilder) {
let mut stacking_context = StackingContext::create_root();
for fragment in &self.children {
fragment.build_stacking_context_tree(
builder,
&self.initial_containing_block,
&mut stacking_context,
);
{
let mut stacking_context_builder = StackingContextBuilder::new(&mut builder.wr);
let containing_block_info = ContainingBlockInfo {
rect: self.initial_containing_block,
nearest_containing_block: None,
containing_block_for_all_descendants: ContainingBlock::new(
&self.initial_containing_block,
stacking_context_builder.current_space_and_clip,
&self.children,
),
};
for fragment in &self.children {
fragment.build_stacking_context_tree(
&mut stacking_context_builder,
&containing_block_info,
&mut stacking_context,
StackingContextBuildMode::SkipHoisted,
);
}
}
stacking_context.sort();
@ -268,6 +285,7 @@ impl FragmentTreeRoot {
Fragment::Box(fragment) if fragment.tag == requested_node => fragment
.border_rect()
.to_physical(fragment.style.writing_mode, &containing_block),
Fragment::AbsoluteOrFixedPositioned(_) => PhysicalRect::zero(),
Fragment::Text(fragment) if fragment.tag == requested_node => fragment
.rect
.to_physical(fragment.parent_style.writing_mode, &containing_block),
@ -301,6 +319,7 @@ impl FragmentTreeRoot {
Fragment::Box(fragment) if fragment.tag == requested_node => {
(&fragment.style, fragment.padding_rect())
},
Fragment::AbsoluteOrFixedPositioned(_) |
Fragment::Box(_) |
Fragment::Text(_) |
Fragment::Image(_) |