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LibWeb: Pass current target box to BFC::run()

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The BFC "context box" is now the outer box of the block formatting
context. Previously the context box was always the current target box,
which made it hard to reason about who was really the containing block
of whom in various places.

Note that IFC still has the containing block as its context box, this
change only affects BFC. However, to clarify the situation in IFC,
I've added a containing_block() getter than returns the context_box().
This commit is contained in:
Andreas Kling 2020-12-06 19:48:02 +01:00
parent b638e74b68
commit 59de4adb60
14 changed files with 138 additions and 156 deletions
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165
Libraries/LibWeb/Layout/BlockFormattingContext.cpp
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@ -51,34 +51,30 @@ bool BlockFormattingContext::is_initial() const
return context_box().is_initial_containing_block();
}
void BlockFormattingContext::run(LayoutMode layout_mode)
void BlockFormattingContext::run(Box& box, LayoutMode layout_mode)
{
if (is_initial()) {
layout_initial_containing_block(layout_mode);
return;
}
// FIXME: BFC currently computes the width+height of the context box.
// FIXME: BFC currently computes the width+height of the target box.
// This is necessary to be able to place absolutely positioned descendants.
// The same work is also done by the parent BFC for each of its blocks..
if (layout_mode == LayoutMode::Default)
compute_width(context_box());
compute_width(box);
layout_floating_children();
layout_floating_children(box);
if (context_box().children_are_inline()) {
layout_inline_children(layout_mode);
if (box.children_are_inline()) {
layout_inline_children(box, layout_mode);
} else {
layout_block_level_children(layout_mode);
layout_block_level_children(box, layout_mode);
}
if (layout_mode == LayoutMode::Default)
compute_height(context_box());
// No need to layout absolute positioned boxes during shrink-to-fit layouts.
if (layout_mode == LayoutMode::Default)
layout_absolutely_positioned_descendants();
compute_height(box);
}
void BlockFormattingContext::compute_width(Box& box)
@ -411,7 +407,7 @@ void BlockFormattingContext::compute_height(Box& box)
}
auto& style = box.style();
auto& containing_block = context_box();
auto& containing_block = *box.containing_block();
CSS::Length specified_height;
@ -438,80 +434,83 @@ void BlockFormattingContext::compute_height(Box& box)
}
}
void BlockFormattingContext::layout_inline_children(LayoutMode layout_mode)
void BlockFormattingContext::layout_inline_children(Box& box, LayoutMode layout_mode)
{
InlineFormattingContext context(context_box(), this);
context.run(layout_mode);
InlineFormattingContext context(box, this);
context.run(box, layout_mode);
}
void BlockFormattingContext::layout_block_level_children(LayoutMode layout_mode)
void BlockFormattingContext::layout_block_level_children(Box& box, LayoutMode layout_mode)
{
float content_height = 0;
float content_width = 0;
context_box().for_each_in_subtree_of_type<Box>([&](auto& box) {
if (box.is_absolutely_positioned() || box.is_floating() || box.containing_block() != &context_box())
box.for_each_child_of_type<Box>([&](auto& child_box) {
if (child_box.is_absolutely_positioned()) {
layout_absolutely_positioned_child(child_box);
return IterationDecision::Continue;
}
if (child_box.is_floating())
return IterationDecision::Continue;
compute_width(box);
layout_inside(box, layout_mode);
compute_height(box);
compute_width(child_box);
layout_inside(child_box, layout_mode);
compute_height(child_box);
if (box.is_replaced())
place_block_level_replaced_element_in_normal_flow(box);
else if (box.is_block())
place_block_level_non_replaced_element_in_normal_flow(box);
if (child_box.is_replaced())
place_block_level_replaced_element_in_normal_flow(child_box, box);
else if (child_box.is_block())
place_block_level_non_replaced_element_in_normal_flow(child_box, box);
else
dbgln("FIXME: Layout::BlockBox::layout_contained_boxes doesn't know how to place a {}", box.class_name());
dbgln("FIXME: BlockFormattingContext::layout_block_level_children() doesn't know how to place a {}", child_box.class_name());
// FIXME: This should be factored differently. It's uncool that we mutate the tree *during* layout!
// Instead, we should generate the marker box during the tree build.
if (is<ListItemBox>(box))
downcast<ListItemBox>(box).layout_marker();
if (is<ListItemBox>(child_box))
downcast<ListItemBox>(child_box).layout_marker();
content_height = max(content_height, box.effective_offset().y() + box.height() + box.box_model().margin_box(box).bottom);
content_width = max(content_width, downcast<Box>(box).width());
content_height = max(content_height, child_box.effective_offset().y() + child_box.height() + child_box.box_model().margin_box(child_box).bottom);
content_width = max(content_width, downcast<Box>(child_box).width());
return IterationDecision::Continue;
});
if (layout_mode != LayoutMode::Default) {
if (context_box().style().width().is_undefined() || context_box().style().width().is_auto())
context_box().set_width(content_width);
if (box.style().width().is_undefined() || box.style().width().is_auto())
box.set_width(content_width);
}
// FIXME: It's not right to always shrink-wrap the context box to the content here.
context_box().set_height(content_height);
// FIXME: It's not right to always shrink-wrap the box to the content here.
box.set_height(content_height);
}
void BlockFormattingContext::place_block_level_replaced_element_in_normal_flow(Box& box)
void BlockFormattingContext::place_block_level_replaced_element_in_normal_flow(Box& child_box, Box& containing_block)
{
auto& containing_block = context_box();
ASSERT(!containing_block.is_absolutely_positioned());
auto& replaced_element_box_model = box.box_model();
auto& replaced_element_box_model = child_box.box_model();
replaced_element_box_model.margin.top = box.style().margin().top.resolved_or_zero(context_box(), containing_block.width());
replaced_element_box_model.margin.bottom = box.style().margin().bottom.resolved_or_zero(context_box(), containing_block.width());
replaced_element_box_model.border.top = CSS::Length::make_px(box.style().border_top().width);
replaced_element_box_model.border.bottom = CSS::Length::make_px(box.style().border_bottom().width);
replaced_element_box_model.padding.top = box.style().padding().top.resolved_or_zero(context_box(), containing_block.width());
replaced_element_box_model.padding.bottom = box.style().padding().bottom.resolved_or_zero(context_box(), containing_block.width());
replaced_element_box_model.margin.top = child_box.style().margin().top.resolved_or_zero(containing_block, containing_block.width());
replaced_element_box_model.margin.bottom = child_box.style().margin().bottom.resolved_or_zero(containing_block, containing_block.width());
replaced_element_box_model.border.top = CSS::Length::make_px(child_box.style().border_top().width);
replaced_element_box_model.border.bottom = CSS::Length::make_px(child_box.style().border_bottom().width);
replaced_element_box_model.padding.top = child_box.style().padding().top.resolved_or_zero(containing_block, containing_block.width());
replaced_element_box_model.padding.bottom = child_box.style().padding().bottom.resolved_or_zero(containing_block, containing_block.width());
float x = replaced_element_box_model.margin.left.to_px(box)
+ replaced_element_box_model.border.left.to_px(box)
+ replaced_element_box_model.padding.left.to_px(box)
+ replaced_element_box_model.offset.left.to_px(box);
float x = replaced_element_box_model.margin.left.to_px(child_box)
+ replaced_element_box_model.border.left.to_px(child_box)
+ replaced_element_box_model.padding.left.to_px(child_box)
+ replaced_element_box_model.offset.left.to_px(child_box);
float y = replaced_element_box_model.margin_box(box).top + context_box().box_model().offset.top.to_px(box);
float y = replaced_element_box_model.margin_box(child_box).top + containing_block.box_model().offset.top.to_px(child_box);
box.set_offset(x, y);
child_box.set_offset(x, y);
}
void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_flow(Box& box)
void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_flow(Box& child_box, Box& containing_block)
{
auto zero_value = CSS::Length::make_px(0);
auto& containing_block = context_box();
auto& box_model = box.box_model();
auto& style = box.style();
auto& box_model = child_box.box_model();
auto& style = child_box.style();
box_model.margin.top = style.margin().top.resolved(zero_value, containing_block, containing_block.width());
box_model.margin.bottom = style.margin().bottom.resolved(zero_value, containing_block, containing_block.width());
@ -520,22 +519,22 @@ void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_fl
box_model.padding.top = style.padding().top.resolved(zero_value, containing_block, containing_block.width());
box_model.padding.bottom = style.padding().bottom.resolved(zero_value, containing_block, containing_block.width());
float x = box_model.margin.left.to_px(box)
+ box_model.border.left.to_px(box)
+ box_model.padding.left.to_px(box)
+ box_model.offset.left.to_px(box);
float x = box_model.margin.left.to_px(child_box)
+ box_model.border.left.to_px(child_box)
+ box_model.padding.left.to_px(child_box)
+ box_model.offset.left.to_px(child_box);
if (containing_block.style().text_align() == CSS::TextAlign::VendorSpecificCenter) {
x = (containing_block.width() / 2) - box.width() / 2;
x = (containing_block.width() / 2) - child_box.width() / 2;
}
float y = box_model.margin_box(box).top
+ box_model.offset.top.to_px(box);
float y = box_model.margin_box(child_box).top
+ box_model.offset.top.to_px(child_box);
// NOTE: Empty (0-height) preceding siblings have their margins collapsed with *their* preceding sibling, etc.
float collapsed_bottom_margin_of_preceding_siblings = 0;
auto* relevant_sibling = box.previous_sibling_of_type<Layout::BlockBox>();
auto* relevant_sibling = child_box.previous_sibling_of_type<Layout::BlockBox>();
while (relevant_sibling != nullptr) {
if (!relevant_sibling->is_absolutely_positioned() && !relevant_sibling->is_floating()) {
collapsed_bottom_margin_of_preceding_siblings = max(collapsed_bottom_margin_of_preceding_siblings, relevant_sibling->box_model().margin.bottom.to_px(*relevant_sibling));
@ -551,7 +550,7 @@ void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_fl
+ relevant_sibling->box_model().border_box(*relevant_sibling).bottom;
// Collapse top margin with bottom margin of preceding siblings if needed
float my_margin_top = box_model.margin.top.to_px(box);
float my_margin_top = box_model.margin.top.to_px(child_box);
if (my_margin_top < 0 || collapsed_bottom_margin_of_preceding_siblings < 0) {
// Negative margins present.
@ -565,7 +564,7 @@ void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_fl
}
}
if (box.style().clear() == CSS::Clear::Left || box.style().clear() == CSS::Clear::Both) {
if (child_box.style().clear() == CSS::Clear::Left || child_box.style().clear() == CSS::Clear::Both) {
if (!m_left_floating_boxes.is_empty()) {
float clearance_y = 0;
for (auto* floating_box : m_left_floating_boxes) {
@ -576,7 +575,7 @@ void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_fl
}
}
if (box.style().clear() == CSS::Clear::Right || box.style().clear() == CSS::Clear::Both) {
if (child_box.style().clear() == CSS::Clear::Right || child_box.style().clear() == CSS::Clear::Both) {
if (!m_right_floating_boxes.is_empty()) {
float clearance_y = 0;
for (auto* floating_box : m_right_floating_boxes) {
@ -587,7 +586,7 @@ void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_fl
}
}
box.set_offset(x, y);
child_box.set_offset(x, y);
}
void BlockFormattingContext::layout_initial_containing_block(LayoutMode layout_mode)
@ -599,9 +598,9 @@ void BlockFormattingContext::layout_initial_containing_block(LayoutMode layout_m
icb.set_width(viewport_rect.width());
layout_floating_children();
layout_floating_children(context_box());
layout_block_level_children(layout_mode);
layout_block_level_children(context_box(), layout_mode);
ASSERT(!icb.children_are_inline());
@ -613,10 +612,6 @@ void BlockFormattingContext::layout_initial_containing_block(LayoutMode layout_m
});
icb.set_height(lowest_bottom);
// No need to layout absolute positioned boxes during shrink-to-fit layouts.
if (layout_mode == LayoutMode::Default)
layout_absolutely_positioned_descendants();
// FIXME: This is a total hack. Make sure any GUI::Widgets are moved into place after layout.
// We should stop embedding GUI::Widgets entirely, since that won't work out-of-process.
icb.for_each_in_subtree_of_type<Layout::WidgetBox>([&](auto& widget) {
@ -625,26 +620,16 @@ void BlockFormattingContext::layout_initial_containing_block(LayoutMode layout_m
});
}
void BlockFormattingContext::layout_absolutely_positioned_descendants()
void BlockFormattingContext::layout_floating_children(Box& box)
{
context_box().for_each_in_subtree_of_type<Box>([&](auto& box) {
if (box.is_absolutely_positioned() && box.containing_block() == &context_box()) {
layout_absolutely_positioned_descendant(box);
}
box.for_each_child_of_type<Box>([&](auto& child_box) {
if (child_box.is_floating())
layout_floating_child(child_box, box);
return IterationDecision::Continue;
});
}
void BlockFormattingContext::layout_floating_children()
{
context_box().for_each_child_of_type<Box>([&](auto& box) {
if (box.is_floating())
layout_floating_child(box);
return IterationDecision::Continue;
});
}
void BlockFormattingContext::layout_floating_child(Box& box)
void BlockFormattingContext::layout_floating_child(Box& box, Box& containing_block)
{
ASSERT(box.is_floating());
@ -653,7 +638,7 @@ void BlockFormattingContext::layout_floating_child(Box& box)
compute_height(box);
// First we place the box normally (to get the right y coordinate.)
place_block_level_non_replaced_element_in_normal_flow(box);
place_block_level_non_replaced_element_in_normal_flow(box, containing_block);
// Then we float it to the left or right.
@ -671,7 +656,7 @@ void BlockFormattingContext::layout_floating_child(Box& box)
auto& previous_floating_box = *m_right_floating_boxes.last();
x = previous_floating_box.effective_offset().x() - box.width();
} else {
x = context_box().width() - box.width();
x = containing_block.width() - box.width();
}
m_right_floating_boxes.append(&box);
}
@ -679,7 +664,7 @@ void BlockFormattingContext::layout_floating_child(Box& box)
box.set_offset(x, y);
}
void BlockFormattingContext::layout_absolutely_positioned_descendant(Box& box)
void BlockFormattingContext::layout_absolutely_positioned_child(Box& box)
{
auto& containing_block = context_box();
auto& box_model = box.box_model();