diff options
Diffstat (limited to 'components/layout_2020/flow/mod.rs')
| -rw-r--r-- | components/layout_2020/flow/mod.rs | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/components/layout_2020/flow/mod.rs b/components/layout_2020/flow/mod.rs index 7f76abd9db8..e881ed61347 100644 --- a/components/layout_2020/flow/mod.rs +++ b/components/layout_2020/flow/mod.rs @@ -67,8 +67,6 @@ impl BlockLevelBox { collected_margin: &mut CollapsedMargin, containing_block: &ContainingBlock, ) -> bool { - // TODO(mrobinson,Loirooriol): Cache margins here so that we don't constantly - // have to keep looking forward when dealing with sequences of floats. let style = match self { BlockLevelBox::SameFormattingContextBlock { ref style, .. } => &style, BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(_) | @@ -399,6 +397,7 @@ fn layout_block_level_children_in_parallel( &mut child_positioning_context, containing_block, /* sequential_layout_state = */ None, + /* collapsible_with_parent_start_margin = */ None, ); (fragment, child_positioning_context) }) @@ -448,6 +447,9 @@ fn layout_block_level_children_sequentially( &mut child_positioning_context, containing_block, Some(&mut *sequential_layout_state), + Some(CollapsibleWithParentStartMargin( + placement_state.next_in_flow_margin_collapses_with_parent_start_margin, + )), ); placement_state.place_fragment(&mut fragment, Some(sequential_layout_state)); @@ -474,6 +476,7 @@ impl BlockLevelBox { positioning_context: &mut PositioningContext, containing_block: &ContainingBlock, sequential_layout_state: Option<&mut SequentialLayoutState>, + collapsible_with_parent_start_margin: Option<CollapsibleWithParentStartMargin>, ) -> Fragment { match self { BlockLevelBox::SameFormattingContextBlock { @@ -493,6 +496,7 @@ impl BlockLevelBox { style, NonReplacedContents::SameFormattingContextBlock(contents), sequential_layout_state, + collapsible_with_parent_start_margin, ) }, )), @@ -529,6 +533,7 @@ impl BlockLevelBox { non_replaced, ), sequential_layout_state, + collapsible_with_parent_start_margin, ) }, )) @@ -591,6 +596,7 @@ fn layout_in_flow_non_replaced_block_level( style: &Arc<ComputedValues>, block_level_kind: NonReplacedContents, mut sequential_layout_state: Option<&mut SequentialLayoutState>, + collapsible_with_parent_start_margin: Option<CollapsibleWithParentStartMargin>, ) -> BoxFragment { let pbm = style.padding_border_margin(containing_block); let box_size = style.content_box_size(containing_block, &pbm); @@ -671,13 +677,27 @@ fn layout_in_flow_non_replaced_block_level( None => parent_containing_block_position_info = None, Some(ref mut sequential_layout_state) => { let mut block_start_margin = CollapsedMargin::new(margin.block_start); - if start_margin_can_collapse_with_children { + + // The block start margin may collapse with content margins, + // compute the resulting one in order to place floats correctly. + // Only need to do this if the element isn't also collapsing with its parent, + // otherwise we should have already included the margin in an ancestor. + // Note this lookahead stops when finding a descendant whose `clear` isn't `none` + // (since clearance prevents collapsing margins with the parent). + // But then we have to decide whether to actually add clearance or not, + // so look forward again regardless of `collapsible_with_parent_start_margin`. + // TODO: This isn't completely right: if we don't add actual clearance, + // the margin should have been included in the parent (or some ancestor). + // The lookahead should stop for actual clearance, not just for `clear`. + let collapsible_with_parent_start_margin = collapsible_with_parent_start_margin.expect( + "We should know whether we are collapsing the block start margin with the parent \ + when laying out sequentially", + ).0 && style.get_box().clear == Clear::None; + if !collapsible_with_parent_start_margin && start_margin_can_collapse_with_children { if let NonReplacedContents::SameFormattingContextBlock( BlockContainer::BlockLevelBoxes(child_boxes), ) = block_level_kind { - // The block start margin may collapse with content margins, - // compute the resulting one in order to place floats correctly. BlockLevelBox::find_block_margin_collapsing_with_parent_from_slice( child_boxes, &mut block_start_margin, |