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LibWeb: Sort stacking context tree once, after fully building it

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Instead of calling quick_sort() every time a StackingContext child
is added to a parent, we now do a single pass of sorting work after the
full StackingContext tree has been built.

Before this change, the quick_sort() was ~13.5% of the profile while
hovering links on GitHub in the Browser. After the change, it's down to
~0.6%. Pretty good! :^)
This commit is contained in:
Andreas Kling 2022-03-13 16:19:54 +01:00
parent 0dfb9714fe
commit f5c2e87965
3 changed files with 18 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

2
Userland/Libraries/LibWeb/Layout/InitialContainingBlock.cpp
View file

@ -36,6 +36,8 @@ void InitialContainingBlock::build_stacking_context_tree()
const_cast<Painting::PaintableBox*>(box.paint_box())->set_stacking_context(make<Painting::StackingContext>(box, parent_context));
return IterationDecision::Continue;
});
const_cast<Painting::PaintableWithLines*>(paint_box())->stacking_context()->sort();
}
void InitialContainingBlock::paint_all_phases(PaintContext& context)

24
Userland/Libraries/LibWeb/Painting/StackingContext.cpp
View file

@ -26,18 +26,22 @@ StackingContext::StackingContext(Layout::Box& box, StackingContext* parent)
, m_parent(parent)
{
VERIFY(m_parent != this);
if (m_parent) {
if (m_parent)
m_parent->m_children.append(this);
}
// FIXME: Don't sort on every append..
quick_sort(m_parent->m_children, [](auto& a, auto& b) {
auto a_z_index = a->m_box.computed_values().z_index().value_or(0);
auto b_z_index = b->m_box.computed_values().z_index().value_or(0);
if (a_z_index == b_z_index)
return a->m_box.is_before(b->m_box);
return a_z_index < b_z_index;
});
}
void StackingContext::sort()
{
quick_sort(m_children, [](auto& a, auto& b) {
auto a_z_index = a->m_box.computed_values().z_index().value_or(0);
auto b_z_index = b->m_box.computed_values().z_index().value_or(0);
if (a_z_index == b_z_index)
return a->m_box.is_before(b->m_box);
return a_z_index < b_z_index;
});
for (auto* child : m_children)
child->sort();
}
void StackingContext::paint_descendants(PaintContext& context, Layout::Node& box, StackingContextPaintPhase phase) const

2
Userland/Libraries/LibWeb/Painting/StackingContext.h
View file

@ -33,6 +33,8 @@ public:
void dump(int indent = 0) const;
void sort();
private:
Layout::Box& m_box;
StackingContext* const m_parent { nullptr };