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layout: Switch display list building from bottom-up to top-down.

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This eliminates a lot of allocations and O(n^2) behavior.
This commit is contained in:
Patrick Walton 2016-03-02 15:41:50 -08:00
parent f4b95dd00b
commit d3d2dd05f2
5 changed files with 35 additions and 58 deletions
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33
components/layout/display_list_builder.rs
View file

@ -18,7 +18,7 @@ use context::LayoutContext;
use euclid::num::Zero;
use euclid::{Matrix4, Point2D, Point3D, Rect, SideOffsets2D, Size2D};
use flex::FlexFlow;
use flow::{self, BaseFlow, Flow, IS_ABSOLUTELY_POSITIONED};
use flow::{BaseFlow, Flow, IS_ABSOLUTELY_POSITIONED};
use flow_ref;
use fragment::{CoordinateSystem, Fragment, HAS_LAYER, ImageFragmentInfo, ScannedTextFragmentInfo};
use fragment::{SpecificFragmentInfo};
@ -86,21 +86,15 @@ impl<'a> DisplayListBuildState<'a> {
});
}
fn append_from(&mut self, other_list: &mut Option<Vec<DisplayListEntry>>) {
if let Some(mut other) = other_list.take() {
self.items.append(&mut other);
}
}
fn stacking_context_id(&self) -> StackingContextId {
self.stacking_context_id_stack.last().unwrap().clone()
}
fn push_stacking_context_id(&mut self, stacking_context_id: StackingContextId) {
pub fn push_stacking_context_id(&mut self, stacking_context_id: StackingContextId) {
self.stacking_context_id_stack.push(stacking_context_id);
}
fn pop_stacking_context_id(&mut self) {
pub fn pop_stacking_context_id(&mut self) {
self.stacking_context_id_stack.pop();
assert!(!self.stacking_context_id_stack.is_empty());
}
@ -1736,11 +1730,6 @@ impl BlockFlowDisplayListBuilding for BlockFlow {
clip,
&self.base.stacking_relative_position_of_display_port);
// Add children.
for kid in self.base.children.iter_mut() {
state.append_from(&mut flow::mut_base(kid).display_list_building_result);
}
self.base.build_display_items_for_debugging_tint(state, self.fragment.node);
}
}
@ -1805,22 +1794,6 @@ impl InlineFlowDisplayListBuilding for InlineFlow {
DisplayListSection::Content,
&self.base.clip,
&self.base.stacking_relative_position_of_display_port);
match fragment.specific {
SpecificFragmentInfo::InlineBlock(ref mut block_flow) => {
let block_flow = flow_ref::deref_mut(&mut block_flow.flow_ref);
state.append_from(&mut flow::mut_base(block_flow).display_list_building_result)
}
SpecificFragmentInfo::InlineAbsoluteHypothetical(ref mut block_flow) => {
let block_flow = flow_ref::deref_mut(&mut block_flow.flow_ref);
state.append_from(&mut flow::mut_base(block_flow).display_list_building_result)
}
SpecificFragmentInfo::InlineAbsolute(ref mut block_flow) => {
let block_flow = flow_ref::deref_mut(&mut block_flow.flow_ref);
state.append_from(&mut flow::mut_base(block_flow).display_list_building_result)
}
_ => {}
}
}
fn build_display_list_for_inline(&mut self, state: &mut DisplayListBuildState) {

8
components/layout/flow.rs
View file

@ -34,7 +34,7 @@ use floats::Floats;
use flow_list::{FlowList, FlowListIterator, MutFlowListIterator};
use flow_ref::{self, FlowRef, WeakFlowRef};
use fragment::{Fragment, FragmentBorderBoxIterator, Overflow, SpecificFragmentInfo};
use gfx::display_list::{ClippingRegion, DisplayListEntry, StackingContext, StackingContextId};
use gfx::display_list::{ClippingRegion, StackingContext, StackingContextId};
use gfx_traits::{LayerId, LayerType};
use incremental::{RECONSTRUCT_FLOW, REFLOW, REFLOW_OUT_OF_FLOW, REPAINT, RestyleDamage};
use inline::InlineFlow;
@ -957,9 +957,6 @@ pub struct BaseFlow {
/// per-stacking-context.
pub stacking_relative_position_of_display_port: Rect<Au>,
/// The results of display list building for this flow.
pub display_list_building_result: Option<Vec<DisplayListEntry>>,
/// The writing mode for this flow.
pub writing_mode: WritingMode,
@ -1129,7 +1126,6 @@ impl BaseFlow {
block_container_writing_mode: writing_mode,
block_container_explicit_block_size: None,
absolute_cb: ContainingBlockLink::new(),
display_list_building_result: None,
early_absolute_position_info: EarlyAbsolutePositionInfo::new(writing_mode),
late_absolute_position_info: LateAbsolutePositionInfo::new(),
clip: ClippingRegion::max(),
@ -1147,8 +1143,6 @@ impl BaseFlow {
children: children,
restyle_damage: self.restyle_damage | REPAINT | REFLOW_OUT_OF_FLOW | REFLOW,
parallel: FlowParallelInfo::new(),
display_list_building_result: None,
floats: self.floats.clone(),
abs_descendants: self.abs_descendants.clone(),
absolute_cb: self.absolute_cb.clone(),

7
components/layout/layout_thread.rs
View file

@ -875,6 +875,7 @@ impl LayoutThread {
false,
None);
let display_list_entries =
sequential::build_display_list_for_subtree(layout_root,
&mut root_stacking_context,
shared_layout_context);
@ -900,11 +901,9 @@ impl LayoutThread {
ScrollPolicy::Scrollable,
None,
root_background_color));
let display_list = DisplayList::new(
root_stacking_context,
&mut flow::mut_base(flow_ref::deref_mut(layout_root))
.display_list_building_result);
let display_list = DisplayList::new(root_stacking_context,
&mut Some(display_list_entries));
if opts::get().dump_display_list {
display_list.print();
}

13
components/layout/sequential.rs
View file

@ -6,13 +6,14 @@
use app_units::Au;
use context::{LayoutContext, SharedLayoutContext};
use display_list_builder::DisplayListBuildState;
use euclid::point::Point2D;
use flow::{PostorderFlowTraversal, PreorderFlowTraversal};
use flow::{self, Flow, ImmutableFlowUtils, InorderFlowTraversal, MutableFlowUtils};
use flow_ref::{self, FlowRef};
use fragment::FragmentBorderBoxIterator;
use generated_content::ResolveGeneratedContent;
use gfx::display_list::StackingContext;
use gfx::display_list::{DisplayListEntry, StackingContext};
use style::dom::TNode;
use style::traversal::DomTraversalContext;
use traversal::{AssignBSizesAndStoreOverflow, AssignISizes};
@ -77,13 +78,19 @@ pub fn traverse_flow_tree_preorder(root: &mut FlowRef,
pub fn build_display_list_for_subtree(root: &mut FlowRef,
root_stacking_context: &mut StackingContext,
shared_layout_context: &SharedLayoutContext) {
shared_layout_context: &SharedLayoutContext)
-> Vec<DisplayListEntry> {
let flow_root = flow_ref::deref_mut(root);
let layout_context = LayoutContext::new(shared_layout_context);
flow_root.traverse_preorder(&ComputeAbsolutePositions { layout_context: &layout_context });
flow_root.collect_stacking_contexts(root_stacking_context.id,
&mut root_stacking_context.children);
flow_root.traverse_postorder(&BuildDisplayList { layout_context: &layout_context });
let mut build_display_list = BuildDisplayList {
state: DisplayListBuildState::new(&layout_context,
flow::base(&**root).stacking_context_id),
};
build_display_list.traverse(&mut *flow_root);
build_display_list.state.items
}
pub fn iterate_through_flow_tree_fragment_border_boxes(root: &mut FlowRef,

24
components/layout/traversal.rs
View file

@ -215,23 +215,27 @@ impl<'a> PreorderFlowTraversal for ComputeAbsolutePositions<'a> {
}
}
#[derive(Copy, Clone)]
pub struct BuildDisplayList<'a> {
pub layout_context: &'a LayoutContext<'a>,
pub state: DisplayListBuildState<'a>,
}
impl<'a> PostorderFlowTraversal for BuildDisplayList<'a> {
impl<'a> BuildDisplayList<'a> {
#[inline]
fn process(&self, flow: &mut Flow) {
let mut state = DisplayListBuildState::new(
self.layout_context, flow::base(flow).stacking_context_id);
flow.build_display_list(&mut state);
flow::mut_base(flow).display_list_building_result = Some(state.items);
pub fn traverse(&mut self, flow: &mut Flow) {
if self.should_process() {
self.state.push_stacking_context_id(flow::base(flow).stacking_context_id);
flow.build_display_list(&mut self.state);
flow::mut_base(flow).restyle_damage.remove(REPAINT);
self.state.pop_stacking_context_id();
}
for kid in flow::child_iter(flow) {
self.traverse(kid);
}
}
#[inline]
fn should_process(&self, _: &mut Flow) -> bool {
self.layout_context.shared_context().goal == ReflowGoal::ForDisplay
fn should_process(&self) -> bool {
self.state.layout_context.shared_context().goal == ReflowGoal::ForDisplay
}
}