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/*
* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/QuickSort.h>
#include <AK/StringBuilder.h>
#include <LibGfx/Painter.h>
#include <LibWeb/Layout/Box.h>
#include <LibWeb/Layout/InitialContainingBlock.h>
#include <LibWeb/Layout/ReplacedBox.h>
#include <LibWeb/Painting/PaintableBox.h>
#include <LibWeb/Painting/StackingContext.h>
namespace Web::Painting {
static void paint_node(Layout::Node const& layout_node, PaintContext& context, PaintPhase phase)
{
if (auto const* paintable = layout_node.paintable())
paintable->paint(context, phase);
}
StackingContext::StackingContext(Layout::Box& box, StackingContext* parent)
: m_box(box)
, m_parent(parent)
{
VERIFY(m_parent != this);
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::paint_descendants(PaintContext& context, Layout::Node& box, StackingContextPaintPhase phase) const
{
if (phase == StackingContextPaintPhase::Foreground) {
if (auto* paintable = box.paintable())
paintable->before_children_paint(context, PaintPhase::Foreground);
}
box.for_each_child([&](auto& child) {
if (child.establishes_stacking_context())
return;
bool child_is_inline_or_replaced = child.is_inline() || is<Layout::ReplacedBox>(child);
switch (phase) {
case StackingContextPaintPhase::BackgroundAndBorders:
if (!child_is_inline_or_replaced && !child.is_floating() && !child.is_positioned()) {
paint_node(child, context, PaintPhase::Background);
paint_node(child, context, PaintPhase::Border);
paint_descendants(context, child, phase);
}
break;
case StackingContextPaintPhase::Floats:
if (!child.is_positioned()) {
if (child.is_floating()) {
paint_node(child, context, PaintPhase::Background);
paint_node(child, context, PaintPhase::Border);
paint_descendants(context, child, StackingContextPaintPhase::BackgroundAndBorders);
}
paint_descendants(context, child, phase);
}
break;
case StackingContextPaintPhase::BackgroundAndBordersForInlineLevelAndReplaced:
if (!child.is_positioned()) {
if (child_is_inline_or_replaced) {
paint_node(child, context, PaintPhase::Background);
paint_node(child, context, PaintPhase::Border);
paint_descendants(context, child, StackingContextPaintPhase::BackgroundAndBorders);
}
paint_descendants(context, child, phase);
}
break;
case StackingContextPaintPhase::Foreground:
if (!child.is_positioned()) {
paint_node(child, context, PaintPhase::Foreground);
paint_descendants(context, child, phase);
}
break;
case StackingContextPaintPhase::FocusAndOverlay:
if (context.has_focus()) {
paint_node(child, context, PaintPhase::FocusOutline);
}
paint_node(child, context, PaintPhase::Overlay);
paint_descendants(context, child, phase);
break;
}
});
if (phase == StackingContextPaintPhase::Foreground) {
if (auto* paintable = box.paintable())
paintable->after_children_paint(context, PaintPhase::Foreground);
}
}
void StackingContext::paint_internal(PaintContext& context) const
{
// 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)
paint_node(m_box, context, PaintPhase::Background);
paint_node(m_box, context, PaintPhase::Border);
// Draw positioned descendants with negative z-indices (step 3)
for (auto* child : m_children) {
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::BackgroundAndBordersForInlineLevelAndReplaced);
paint_node(m_box, context, PaintPhase::Foreground);
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);
}
paint_node(m_box, context, PaintPhase::FocusOutline);
paint_node(m_box, context, PaintPhase::Overlay);
paint_descendants(context, m_box, StackingContextPaintPhase::FocusAndOverlay);
}
void StackingContext::paint(PaintContext& context) const
{
Gfx::PainterStateSaver saver(context.painter());
if (m_box.is_fixed_position()) {
context.painter().translate(context.scroll_offset());
}
auto opacity = m_box.computed_values().opacity();
if (opacity == 0.0f)
return;
if (opacity < 1.0f) {
auto bitmap_or_error = Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, context.painter().target()->size());
if (bitmap_or_error.is_error())
return;
auto bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
Gfx::Painter painter(bitmap);
PaintContext paint_context(painter, context.palette(), context.scroll_offset());
paint_internal(paint_context);
context.painter().blit(Gfx::IntPoint(m_box.paint_box()->absolute_position()), bitmap, Gfx::IntRect(m_box.paint_box()->absolute_rect()), opacity);
} else {
paint_internal(context);
}
}
HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestType type) const
{
// NOTE: Hit testing basically happens in reverse painting order.
// https://www.w3.org/TR/CSS22/visuren.html#z-index
// 7. the child stacking contexts with positive stack levels (least positive first).
for (ssize_t i = m_children.size() - 1; i >= 0; --i) {
auto const& child = *m_children[i];
if (child.m_box.computed_values().z_index().value_or(0) < 0)
break;
auto result = child.hit_test(position, type);
if (result.paintable)
return result;
}
HitTestResult result;
// 6. the child stacking contexts with stack level 0 and the positioned descendants with stack level 0.
m_box.for_each_in_subtree_of_type<Layout::Box>([&](Layout::Box const& box) {
if (box.is_positioned() && !box.paint_box()->stacking_context()) {
result = box.paint_box()->hit_test(position, type);
if (result.paintable)
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
if (result.paintable)
return result;
// 5. the in-flow, inline-level, non-positioned descendants, including inline tables and inline blocks.
if (m_box.children_are_inline() && is<Layout::BlockContainer>(m_box)) {
auto result = m_box.paint_box()->hit_test(position, type);
if (result.paintable)
return result;
}
// 4. the non-positioned floats.
m_box.for_each_in_subtree_of_type<Layout::Box>([&](Layout::Box const& box) {
if (box.is_floating()) {
result = box.paint_box()->hit_test(position, type);
if (result.paintable)
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
// 3. the in-flow, non-inline-level, non-positioned descendants.
if (!m_box.children_are_inline()) {
m_box.for_each_in_subtree_of_type<Layout::Box>([&](Layout::Box const& box) {
if (!box.is_absolutely_positioned() && !box.is_floating()) {
result = box.paint_box()->hit_test(position, type);
if (result.paintable)
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
if (result.paintable)
return result;
}
// 2. the child stacking contexts with negative stack levels (most negative first).
for (ssize_t i = m_children.size() - 1; i >= 0; --i) {
auto const& child = *m_children[i];
if (child.m_box.computed_values().z_index().value_or(0) < 0)
break;
auto result = child.hit_test(position, type);
if (result.paintable)
return result;
}
// 1. the background and borders of the element forming the stacking context.
if (m_box.paint_box()->absolute_border_box_rect().contains(position.to_type<float>())) {
return HitTestResult {
.paintable = m_box.paintable(),
};
}
return {};
}
void StackingContext::dump(int indent) const
{
StringBuilder builder;
for (int i = 0; i < indent; ++i)
builder.append(' ');
builder.appendff("SC for {} {} [children: {}] (z-index: ", m_box.debug_description(), m_box.paint_box()->absolute_rect(), m_children.size());
if (m_box.computed_values().z_index().has_value())
builder.appendff("{}", m_box.computed_values().z_index().value());
else
builder.append("auto");
builder.append(')');
dbgln("{}", builder.string_view());
for (auto& child : m_children)
child->dump(indent + 1);
}
}
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