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LibWeb: Make painting order more spec-compliant

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Now our painting order inside stacking contexts is closer to the
algorithm specified by CSS 2.1 (see section 9.9 and Appendix E)
This commit is contained in:
Egor Ananyin 2021-05-07 19:03:25 +03:00 • committed by Andreas Kling
parent 33af7075e7
commit d2b6148787
8 changed files with 89 additions and 43 deletions
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74
Userland/Libraries/LibWeb/Painting/StackingContext.cpp
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@ -22,24 +22,80 @@ StackingContext::StackingContext(Box& box, StackingContext* parent)
m_parent->m_children.append(this);
// FIXME: Don't sort on every append..
// FIXME: Apparently this also breaks tree order inside layers
quick_sort(m_parent->m_children, [](auto& a, auto& b) {
return a->m_box.computed_values().z_index().value_or(0) < b->m_box.computed_values().z_index().value_or(0);
});
}
}
void StackingContext::paint(PaintContext& context, PaintPhase phase)
void StackingContext::paint_descendants(PaintContext& context, Node& box, StackingContextPaintPhase phase)
{
if (!is<InitialContainingBlockBox>(m_box)) {
m_box.paint(context, phase);
} else {
// NOTE: InitialContainingBlockBox::paint() merely calls StackingContext::paint()
// so we call its base class instead.
downcast<InitialContainingBlockBox>(m_box).BlockBox::paint(context, phase);
}
box.for_each_child([&](auto& child) {
switch (phase) {
case StackingContextPaintPhase::BackgroundAndBorders:
if (!child.is_floating() && !child.is_positioned()) {
child.paint(context, PaintPhase::Background);
child.paint(context, PaintPhase::Border);
paint_descendants(context, child, phase);
}
break;
case StackingContextPaintPhase::Floats:
if (!child.is_positioned()) {
if (child.is_floating()) {
child.paint(context, PaintPhase::Background);
child.paint(context, PaintPhase::Border);
paint_descendants(context, child, StackingContextPaintPhase::BackgroundAndBorders);
}
paint_descendants(context, child, phase);
}
break;
case StackingContextPaintPhase::Foreground:
if (!child.is_positioned()) {
child.paint(context, PaintPhase::Foreground);
child.before_children_paint(context, PaintPhase::Foreground);
paint_descendants(context, child, phase);
child.after_children_paint(context, PaintPhase::Foreground);
}
break;
case StackingContextPaintPhase::FocusAndOverlay:
if (context.has_focus()) {
child.paint(context, PaintPhase::FocusOutline);
}
child.paint(context, PaintPhase::Overlay);
paint_descendants(context, child, phase);
break;
}
});
}
void StackingContext::paint(PaintContext& context)
{
// For a more elaborate description of the algorithm, see CSS 2.1 Appendix E
// Draw the background and borders for the context root (steps 1, 2)
m_box.paint(context, PaintPhase::Background);
m_box.paint(context, PaintPhase::Border);
// Draw positioned descendants with negative z-indices (step 3)
for (auto* child : m_children) {
child->paint(context, phase);
if (child->m_box.computed_values().z_index().has_value() && child->m_box.computed_values().z_index().value() < 0)
child->paint(context);
}
// Draw the background and borders for block-level children (step 4)
paint_descendants(context, m_box, StackingContextPaintPhase::BackgroundAndBorders);
// Draw the non-positioned floats (step 5)
paint_descendants(context, m_box, StackingContextPaintPhase::Floats);
// Draw inline content, replaced content, etc. (steps 6, 7)
paint_descendants(context, m_box, StackingContextPaintPhase::Foreground);
// Draw other positioned descendants (steps 8, 9)
for (auto* child : m_children) {
if (child->m_box.computed_values().z_index().has_value() && child->m_box.computed_values().z_index().value() < 0)
continue;
child->paint(context);
}
m_box.paint(context, PaintPhase::FocusOutline);
m_box.paint(context, PaintPhase::Overlay);
paint_descendants(context, m_box, StackingContextPaintPhase::FocusAndOverlay);
}
HitTestResult StackingContext::hit_test(const Gfx::IntPoint& position, HitTestType type) const