0ct0pu5/ladybird
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 2
ladybird/Userland/Libraries/LibWeb/Layout/BlockFormattingContext.cpp
Andreas Kling c9700e100e LibWeb: Start making our layout system "transactional" 
This patch adds a map of Layout::Node to FormattingState::NodeState.
Instead of updating layout nodes incrementally as layout progresses
through the formatting contexts, all updates are now written to the
corresponding NodeState instead.

At the end of layout, FormattingState::commit() is called, which
transfers all the values from the NodeState objects to the Node.

This will soon allow us to perform completely non-destructive layouts
which don't affect the tree.

Note that there are many imperfections here, and still many places
where we assign to the NodeState, but later read directly from the Node
instead. I'm just committing at this stage to make subsequent diffs
easier to understand.
2022-02-21 18:35:12 +01:00

666 lines
32 KiB
C++
Raw Blame History

/*
* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/CSS/Length.h>
#include <LibWeb/DOM/Node.h>
#include <LibWeb/HTML/BrowsingContext.h>
#include <LibWeb/Layout/BlockContainer.h>
#include <LibWeb/Layout/BlockFormattingContext.h>
#include <LibWeb/Layout/Box.h>
#include <LibWeb/Layout/InitialContainingBlock.h>
#include <LibWeb/Layout/InlineFormattingContext.h>
#include <LibWeb/Layout/ListItemBox.h>
#include <LibWeb/Layout/ListItemMarkerBox.h>
#include <LibWeb/Layout/ReplacedBox.h>
namespace Web::Layout {
BlockFormattingContext::BlockFormattingContext(FormattingState& state, BlockContainer const& root, FormattingContext* parent)
: FormattingContext(Type::Block, state, root, parent)
{
}
BlockFormattingContext::~BlockFormattingContext()
{
if (!m_was_notified_after_parent_dimensioned_my_root_box) {
// HACK: The parent formatting context never notified us after assigning dimensions to our root box.
// Pretend that it did anyway, to make sure absolutely positioned children get laid out.
// FIXME: Get rid of this hack once parent contexts behave properly.
parent_context_did_dimension_child_root_box();
}
}
bool BlockFormattingContext::is_initial() const
{
return is<InitialContainingBlock>(root());
}
void BlockFormattingContext::run(Box const&, LayoutMode layout_mode)
{
if (is_initial()) {
layout_initial_containing_block(layout_mode);
return;
}
if (root().children_are_inline())
layout_inline_children(root(), layout_mode);
else
layout_block_level_children(root(), layout_mode);
}
void BlockFormattingContext::parent_context_did_dimension_child_root_box()
{
m_was_notified_after_parent_dimensioned_my_root_box = true;
for (auto& box : m_absolutely_positioned_boxes)
layout_absolutely_positioned_element(box);
apply_transformations_to_children(root());
}
void BlockFormattingContext::apply_transformations_to_children(Box const& box)
{
box.for_each_child_of_type<Box>([&](auto& child_box) {
float transform_y_offset = 0.0f;
if (!child_box.computed_values().transformations().is_empty()) {
// FIXME: All transformations can be interpreted as successive 3D-matrix operations on the box, we don't do that yet.
// https://drafts.csswg.org/css-transforms/#serialization-of-the-computed-value
for (auto transformation : child_box.computed_values().transformations()) {
switch (transformation.function) {
case CSS::TransformFunction::TranslateY:
if (transformation.values.size() != 1)
continue;
transformation.values.first().visit(
[&](CSS::Length& value) {
transform_y_offset += value.to_px(child_box);
},
[&](float value) {
transform_y_offset += value;
},
[&](auto&) {
dbgln("FIXME: Implement unsupported transformation function value type!");
});
break;
default:
dbgln("FIXME: Implement missing transform function!");
}
}
}
auto& child_box_state = m_state.ensure(child_box);
auto untransformed_offset = child_box_state.offset;
child_box_state.offset = Gfx::FloatPoint { untransformed_offset.x(), untransformed_offset.y() + transform_y_offset };
});
}
void BlockFormattingContext::compute_width(Box const& box)
{
if (box.is_absolutely_positioned()) {
compute_width_for_absolutely_positioned_element(box);
return;
}
if (is<ReplacedBox>(box)) {
// FIXME: This should not be done *by* ReplacedBox
auto& replaced = verify_cast<ReplacedBox>(box);
// FIXME: This const_cast is gross.
const_cast<ReplacedBox&>(replaced).prepare_for_replaced_layout();
compute_width_for_block_level_replaced_element_in_normal_flow(replaced);
return;
}
if (box.is_floating()) {
compute_width_for_floating_box(box);
return;
}
auto const& computed_values = box.computed_values();
float width_of_containing_block = m_state.get(*box.containing_block()).content_width;
auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
auto zero_value = CSS::Length::make_px(0);
auto margin_left = CSS::Length::make_auto();
auto margin_right = CSS::Length::make_auto();
const auto padding_left = computed_values.padding().left.resolved(box, width_of_containing_block_as_length).resolved(box);
const auto padding_right = computed_values.padding().right.resolved(box, width_of_containing_block_as_length).resolved(box);
auto try_compute_width = [&](const auto& a_width) {
CSS::Length width = a_width;
margin_left = computed_values.margin().left.resolved(box, width_of_containing_block_as_length).resolved(box);
margin_right = computed_values.margin().right.resolved(box, width_of_containing_block_as_length).resolved(box);
float total_px = computed_values.border_left().width + computed_values.border_right().width;
for (auto& value : { margin_left, padding_left, width, padding_right, margin_right }) {
total_px += value.to_px(box);
}
if (!box.is_inline()) {
// 10.3.3 Block-level, non-replaced elements in normal flow
// If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
if (width.is_auto() && total_px > width_of_containing_block) {
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
}
// 10.3.3 cont'd.
auto underflow_px = width_of_containing_block - total_px;
if (width.is_auto()) {
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
if (underflow_px >= 0) {
width = CSS::Length(underflow_px, CSS::Length::Type::Px);
} else {
width = zero_value;
margin_right = CSS::Length(margin_right.to_px(box) + underflow_px, CSS::Length::Type::Px);
}
} else {
if (!margin_left.is_auto() && !margin_right.is_auto()) {
margin_right = CSS::Length(margin_right.to_px(box) + underflow_px, CSS::Length::Type::Px);
} else if (!margin_left.is_auto() && margin_right.is_auto()) {
margin_right = CSS::Length(underflow_px, CSS::Length::Type::Px);
} else if (margin_left.is_auto() && !margin_right.is_auto()) {
margin_left = CSS::Length(underflow_px, CSS::Length::Type::Px);
} else { // margin_left.is_auto() && margin_right.is_auto()
auto half_of_the_underflow = CSS::Length(underflow_px / 2, CSS::Length::Type::Px);
margin_left = half_of_the_underflow;
margin_right = half_of_the_underflow;
}
}
} else if (box.is_inline_block()) {
// 10.3.9 'Inline-block', non-replaced elements in normal flow
// A computed value of 'auto' for 'margin-left' or 'margin-right' becomes a used value of '0'.
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
// If 'width' is 'auto', the used value is the shrink-to-fit width as for floating elements.
if (width.is_auto()) {
// Find the available width: in this case, this is the width of the containing
// block minus the used values of 'margin-left', 'border-left-width', 'padding-left',
// 'padding-right', 'border-right-width', 'margin-right', and the widths of any relevant scroll bars.
float available_width = width_of_containing_block
- margin_left.to_px(box) - computed_values.border_left().width - padding_left.to_px(box)
- padding_right.to_px(box) - computed_values.border_right().width - margin_right.to_px(box);
auto result = calculate_shrink_to_fit_widths(box);
// Then the shrink-to-fit width is: min(max(preferred minimum width, available width), preferred width).
width = CSS::Length(min(max(result.preferred_minimum_width, available_width), result.preferred_width), CSS::Length::Type::Px);
}
}
return width;
};
auto specified_width = computed_values.width().has_value() ? computed_values.width()->resolved(box, width_of_containing_block_as_length).resolved(box) : CSS::Length::make_auto();
// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
auto used_width = try_compute_width(specified_width);
// 2. The tentative used width is greater than 'max-width', the rules above are applied again,
// but this time using the computed value of 'max-width' as the computed value for 'width'.
auto specified_max_width = computed_values.max_width().has_value() ? computed_values.max_width()->resolved(box, width_of_containing_block_as_length).resolved(box) : CSS::Length::make_auto();
if (!specified_max_width.is_auto()) {
if (used_width.to_px(box) > specified_max_width.to_px(box)) {
used_width = try_compute_width(specified_max_width);
}
}
// 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
// but this time using the value of 'min-width' as the computed value for 'width'.
auto specified_min_width = computed_values.min_width().has_value() ? computed_values.min_width()->resolved(box, width_of_containing_block_as_length).resolved(box) : CSS::Length::make_auto();
if (!specified_min_width.is_auto()) {
if (used_width.to_px(box) < specified_min_width.to_px(box)) {
used_width = try_compute_width(specified_min_width);
}
}
auto& box_state = m_state.ensure(box);
box_state.content_width = used_width.to_px(box);
box_state.margin_left = margin_left.to_px(box);
box_state.margin_right = margin_right.to_px(box);
box_state.border_left = computed_values.border_left().width;
box_state.border_right = computed_values.border_right().width;
box_state.padding_left = padding_left.to_px(box);
box_state.padding_right = padding_right.to_px(box);
}
void BlockFormattingContext::compute_width_for_floating_box(Box const& box)
{
// 10.3.5 Floating, non-replaced elements
auto& computed_values = box.computed_values();
auto& containing_block = *box.containing_block();
float width_of_containing_block = m_state.get(containing_block).content_width;
auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
auto zero_value = CSS::Length::make_px(0);
auto margin_left = computed_values.margin().left.resolved(box, width_of_containing_block_as_length).resolved(box);
auto margin_right = computed_values.margin().right.resolved(box, width_of_containing_block_as_length).resolved(box);
const auto padding_left = computed_values.padding().left.resolved(box, width_of_containing_block_as_length).resolved(box);
const auto padding_right = computed_values.padding().right.resolved(box, width_of_containing_block_as_length).resolved(box);
// If 'margin-left', or 'margin-right' are computed as 'auto', their used value is '0'.
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
auto width = computed_values.width().has_value() ? computed_values.width()->resolved(box, width_of_containing_block_as_length).resolved(box) : CSS::Length::make_auto();
// If 'width' is computed as 'auto', the used value is the "shrink-to-fit" width.
if (width.is_auto()) {
// Find the available width: in this case, this is the width of the containing
// block minus the used values of 'margin-left', 'border-left-width', 'padding-left',
// 'padding-right', 'border-right-width', 'margin-right', and the widths of any relevant scroll bars.
float available_width = width_of_containing_block
- margin_left.to_px(box) - computed_values.border_left().width - padding_left.to_px(box)
- padding_right.to_px(box) - computed_values.border_right().width - margin_right.to_px(box);
auto result = calculate_shrink_to_fit_widths(box);
// Then the shrink-to-fit width is: min(max(preferred minimum width, available width), preferred width).
width = CSS::Length(min(max(result.preferred_minimum_width, available_width), result.preferred_width), CSS::Length::Type::Px);
}
auto& box_state = m_state.ensure(box);
box_state.content_width = width.to_px(box);
box_state.margin_left = margin_left.to_px(box);
box_state.margin_right = margin_right.to_px(box);
box_state.border_left = computed_values.border_left().width;
box_state.border_right = computed_values.border_right().width;
box_state.padding_left = padding_left.to_px(box);
box_state.padding_right = padding_right.to_px(box);
}
void BlockFormattingContext::compute_width_for_block_level_replaced_element_in_normal_flow(ReplacedBox const& box)
{
m_state.ensure(box).content_width = compute_width_for_replaced_element(m_state, box);
}
float BlockFormattingContext::compute_theoretical_height(FormattingState const& state, Box const& box)
{
auto const& computed_values = box.computed_values();
auto const& containing_block = *box.containing_block();
auto const& containing_block_state = state.get(containing_block);
auto containing_block_height = CSS::Length::make_px(containing_block_state.content_height);
auto is_absolute = [](Optional<CSS::LengthPercentage> const& length_percentage) {
return length_percentage.has_value() && length_percentage->is_length() && length_percentage->length().is_absolute();
};
// Then work out what the height is, based on box type and CSS properties.
float height = 0;
if (is<ReplacedBox>(box)) {
height = compute_height_for_replaced_element(state, verify_cast<ReplacedBox>(box));
} else {
if (!box.computed_values().height().has_value()
|| (box.computed_values().height()->is_length() && box.computed_values().height()->length().is_auto())
|| (computed_values.height().has_value() && computed_values.height()->is_percentage() && !is_absolute(containing_block.computed_values().height()))) {
height = compute_auto_height_for_block_level_element(state, box, ConsiderFloats::No);
} else {
height = computed_values.height().has_value() ? computed_values.height()->resolved(box, containing_block_height).to_px(box) : 0;
}
}
auto specified_max_height = computed_values.max_height().has_value() ? computed_values.max_height()->resolved(box, containing_block_height).resolved(box) : CSS::Length::make_auto();
if (!specified_max_height.is_auto()
&& !(computed_values.max_height().has_value() && computed_values.max_height()->is_percentage() && !is_absolute(containing_block.computed_values().height())))
height = min(height, specified_max_height.to_px(box));
auto specified_min_height = computed_values.min_height().has_value() ? computed_values.min_height()->resolved(box, containing_block_height).resolved(box) : CSS::Length::make_auto();
if (!specified_min_height.is_auto()
&& !(computed_values.min_height().has_value() && computed_values.min_height()->is_percentage() && !is_absolute(containing_block.computed_values().height())))
height = max(height, specified_min_height.to_px(box));
return height;
}
void BlockFormattingContext::compute_height(Box const& box, FormattingState& state)
{
auto const& computed_values = box.computed_values();
auto const& containing_block = *box.containing_block();
auto width_of_containing_block_as_length = CSS::Length::make_px(state.get(containing_block).content_width);
// First, resolve the top/bottom parts of the surrounding box model.
auto& box_state = state.ensure(box);
// FIXME: While negative values are generally allowed for margins, for now just ignore those for height calculation
box_state.margin_top = max(computed_values.margin().top.resolved(box, width_of_containing_block_as_length).to_px(box), 0);
box_state.margin_bottom = max(computed_values.margin().bottom.resolved(box, width_of_containing_block_as_length).to_px(box), 0);
box_state.border_top = computed_values.border_top().width;
box_state.border_bottom = computed_values.border_bottom().width;
box_state.padding_top = computed_values.padding().top.resolved(box, width_of_containing_block_as_length).to_px(box);
box_state.padding_bottom = computed_values.padding().bottom.resolved(box, width_of_containing_block_as_length).to_px(box);
box_state.content_height = compute_theoretical_height(state, box);
}
void BlockFormattingContext::layout_inline_children(BlockContainer const& block_container, LayoutMode layout_mode)
{
VERIFY(block_container.children_are_inline());
InlineFormattingContext context(m_state, block_container, *this);
context.run(block_container, layout_mode);
}
void BlockFormattingContext::layout_block_level_children(BlockContainer const& block_container, LayoutMode layout_mode)
{
VERIFY(!block_container.children_are_inline());
float content_height = 0;
float content_width = 0;
block_container.for_each_child_of_type<Box>([&](Box& child_box) {
auto& box_state = m_state.ensure(child_box);
if (child_box.is_absolutely_positioned()) {
m_absolutely_positioned_boxes.append(child_box);
return IterationDecision::Continue;
}
// NOTE: ListItemMarkerBoxes are placed by their corresponding ListItemBox.
if (is<ListItemMarkerBox>(child_box))
return IterationDecision::Continue;
if (child_box.is_floating()) {
layout_floating_child(child_box, block_container);
return IterationDecision::Continue;
}
compute_width(child_box);
if (is<ReplacedBox>(child_box) || is<BlockContainer>(child_box))
place_block_level_element_in_normal_flow_vertically(child_box, block_container);
if (child_box.has_definite_height()) {
compute_height(child_box, m_state);
}
OwnPtr<FormattingContext> independent_formatting_context;
if (child_box.can_have_children()) {
independent_formatting_context = create_independent_formatting_context_if_needed(child_box);
if (independent_formatting_context)
independent_formatting_context->run(child_box, layout_mode);
else
layout_block_level_children(verify_cast<BlockContainer>(child_box), layout_mode);
}
compute_height(child_box, m_state);
compute_position(child_box);
if (is<ReplacedBox>(child_box) || is<BlockContainer>(child_box))
place_block_level_element_in_normal_flow_horizontally(child_box, block_container);
// 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>(child_box))
verify_cast<ListItemBox>(child_box).layout_marker();
content_height = max(content_height, box_state.offset.y() + box_state.content_height + box_state.margin_box_bottom());
content_width = max(content_width, box_state.content_width);
if (independent_formatting_context)
independent_formatting_context->parent_context_did_dimension_child_root_box();
return IterationDecision::Continue;
});
if (layout_mode != LayoutMode::Default) {
auto& width = block_container.computed_values().width();
if (!width.has_value() || (width->is_length() && width->length().is_auto())) {
auto& block_container_state = m_state.ensure(block_container);
block_container_state.content_width = content_width;
}
}
}
void BlockFormattingContext::compute_vertical_box_model_metrics(Box const& box, BlockContainer const& containing_block)
{
auto& box_state = m_state.ensure(box);
auto const& computed_values = box.computed_values();
auto width_of_containing_block = CSS::Length::make_px(m_state.get(containing_block).content_width);
box_state.margin_top = computed_values.margin().top.resolved(box, width_of_containing_block).resolved(containing_block).to_px(box);
box_state.margin_bottom = computed_values.margin().bottom.resolved(box, width_of_containing_block).resolved(containing_block).to_px(box);
box_state.border_top = computed_values.border_top().width;
box_state.border_bottom = computed_values.border_bottom().width;
box_state.padding_top = computed_values.padding().top.resolved(box, width_of_containing_block).resolved(containing_block).to_px(box);
box_state.padding_bottom = computed_values.padding().bottom.resolved(box, width_of_containing_block).resolved(containing_block).to_px(box);
}
void BlockFormattingContext::place_block_level_element_in_normal_flow_vertically(Box const& child_box, BlockContainer const& containing_block)
{
auto& box_state = m_state.ensure(child_box);
auto const& computed_values = child_box.computed_values();
compute_vertical_box_model_metrics(child_box, containing_block);
float y = box_state.margin_box_top()
+ box_state.offset_top;
// 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 = child_box.previous_sibling_of_type<Layout::BlockContainer>();
while (relevant_sibling != nullptr) {
if (!relevant_sibling->is_absolutely_positioned() && !relevant_sibling->is_floating()) {
auto const& relevant_sibling_state = m_state.get(*relevant_sibling);
collapsed_bottom_margin_of_preceding_siblings = max(collapsed_bottom_margin_of_preceding_siblings, relevant_sibling_state.margin_bottom);
if (relevant_sibling_state.border_box_height() > 0)
break;
}
relevant_sibling = relevant_sibling->previous_sibling();
}
if (relevant_sibling) {
auto const& relevant_sibling_state = m_state.get(*relevant_sibling);
y += relevant_sibling_state.offset.y()
+ relevant_sibling_state.content_height
+ relevant_sibling_state.border_box_bottom();
// Collapse top margin with bottom margin of preceding siblings if needed
float my_margin_top = box_state.margin_top;
if (my_margin_top < 0 || collapsed_bottom_margin_of_preceding_siblings < 0) {
// Negative margins present.
float largest_negative_margin = -min(my_margin_top, collapsed_bottom_margin_of_preceding_siblings);
float largest_positive_margin = (my_margin_top < 0 && collapsed_bottom_margin_of_preceding_siblings < 0) ? 0 : max(my_margin_top, collapsed_bottom_margin_of_preceding_siblings);
float final_margin = largest_positive_margin - largest_negative_margin;
y += final_margin - my_margin_top;
} else if (collapsed_bottom_margin_of_preceding_siblings > my_margin_top) {
// Sibling's margin is larger than mine, adjust so we use sibling's.
y += collapsed_bottom_margin_of_preceding_siblings - my_margin_top;
}
}
auto clear_floating_boxes = [&](FloatSideData& float_side) {
if (!float_side.boxes.is_empty()) {
float clearance_y = 0;
for (auto const& floating_box : float_side.boxes) {
auto const& floating_box_state = m_state.get(floating_box);
clearance_y = max(clearance_y, floating_box_state.offset.y() + floating_box_state.border_box_height());
}
y = max(y, clearance_y);
float_side.boxes.clear();
float_side.y_offset = 0;
}
};
// Flex-items don't float and also don't clear.
if ((computed_values.clear() == CSS::Clear::Left || computed_values.clear() == CSS::Clear::Both) && !child_box.is_flex_item())
clear_floating_boxes(m_left_floats);
if ((computed_values.clear() == CSS::Clear::Right || computed_values.clear() == CSS::Clear::Both) && !child_box.is_flex_item())
clear_floating_boxes(m_right_floats);
box_state.offset = Gfx::FloatPoint { box_state.offset.x(), y };
}
void BlockFormattingContext::place_block_level_element_in_normal_flow_horizontally(Box const& child_box, BlockContainer const& containing_block)
{
auto& box_state = m_state.ensure(child_box);
auto const& containing_block_state = m_state.get(containing_block);
float x = 0;
if (containing_block.computed_values().text_align() == CSS::TextAlign::LibwebCenter) {
x = (containing_block_state.content_width / 2) - box_state.content_width / 2;
} else {
x = box_state.margin_box_left() + box_state.offset_left;
}
box_state.offset = Gfx::FloatPoint { x, box_state.offset.y() };
}
void BlockFormattingContext::layout_initial_containing_block(LayoutMode layout_mode)
{
auto viewport_rect = root().browsing_context().viewport_rect();
auto& icb = verify_cast<Layout::InitialContainingBlock>(root());
VERIFY(!icb.children_are_inline());
layout_block_level_children(root(), layout_mode);
// Compute scrollable overflow.
float bottom_edge = 0;
float right_edge = 0;
icb.for_each_in_subtree_of_type<Box>([&](Box const& child) {
auto const& child_state = m_state.get(child);
auto child_rect = absolute_content_rect(child, m_state);
child_rect.inflate(child_state.border_box_top(), child_state.border_box_right(), child_state.border_box_bottom(), child_state.border_box_left());
bottom_edge = max(bottom_edge, child_rect.bottom());
right_edge = max(right_edge, child_rect.right());
return IterationDecision::Continue;
});
if (bottom_edge >= viewport_rect.height() || right_edge >= viewport_rect.width()) {
// FIXME: Move overflow data to FormattingState!
auto& overflow_data = const_cast<InitialContainingBlock&>(icb).ensure_overflow_data();
overflow_data.scrollable_overflow_rect = viewport_rect.to_type<float>();
// NOTE: The edges are *within* the rectangle, so we add 1 to get the width and height.
overflow_data.scrollable_overflow_rect.set_size(right_edge + 1, bottom_edge + 1);
} else {
// FIXME: Move overflow data to FormattingState!
const_cast<InitialContainingBlock&>(icb).clear_overflow_data();
}
}
void BlockFormattingContext::layout_floating_child(Box const& box, BlockContainer const& containing_block)
{
VERIFY(box.is_floating());
auto& box_state = m_state.ensure(box);
auto containing_block_content_width = m_state.get(containing_block).content_width;
compute_width(box);
(void)layout_inside(box, LayoutMode::Default);
compute_height(box, m_state);
// First we place the box normally (to get the right y coordinate.)
place_block_level_element_in_normal_flow_vertically(box, containing_block);
place_block_level_element_in_normal_flow_horizontally(box, containing_block);
auto float_box = [&](FloatSide side, FloatSideData& side_data) {
auto first_edge = [&](FormattingState::NodeState const& thing) { return side == FloatSide::Left ? thing.margin_left : thing.margin_right; };
auto second_edge = [&](FormattingState::NodeState const& thing) { return side == FloatSide::Right ? thing.margin_left : thing.margin_right; };
auto first_edge_of_margin_box = [&](FormattingState::NodeState const& thing) { return side == FloatSide::Left ? thing.margin_box_left() : thing.margin_box_right(); };
// Then we float it to the left or right.
float x = box_state.offset.x();
auto box_in_root_rect = margin_box_rect_in_ancestor_coordinate_space(box, root(), m_state);
float y_in_root = box_in_root_rect.y();
float y = box_state.offset.y();
if (side_data.boxes.is_empty()) {
// This is the first floating box on this side. Go all the way to the edge.
if (side == FloatSide::Left)
x = box_state.margin_box_left();
else
x = containing_block_content_width - box_state.margin_box_right() - box_state.content_width;
side_data.y_offset = 0;
} else {
auto& previous_box = side_data.boxes.last();
auto const& previous_box_state = m_state.get(previous_box);
auto previous_rect = margin_box_rect_in_ancestor_coordinate_space(previous_box, root(), m_state);
auto margin_collapsed_with_previous = max(
second_edge(previous_box_state),
first_edge(box_state));
float wanted_x = 0;
bool fits_on_line = false;
if (side == FloatSide::Left) {
auto previous_right_border_edge = previous_box_state.offset.x()
+ previous_box_state.content_width
+ previous_box_state.padding_right
+ previous_box_state.border_right
+ margin_collapsed_with_previous;
wanted_x = previous_right_border_edge + box_state.border_left + box_state.padding_left;
fits_on_line = (wanted_x + box_state.content_width + box_state.padding_right + box_state.border_right + box_state.margin_right) <= containing_block_content_width;
} else {
auto previous_left_border_edge = previous_box_state.offset.x()
- previous_box_state.content_width
- previous_box_state.padding_left
- previous_box_state.border_left
- margin_collapsed_with_previous;
wanted_x = previous_left_border_edge - box_state.border_right - box_state.padding_right - box_state.content_width;
fits_on_line = (wanted_x - box_state.padding_left - box_state.border_left - box_state.margin_left) >= 0;
}
if (fits_on_line) {
if (previous_rect.contains_vertically(y_in_root + side_data.y_offset)) {
// This box touches another already floating box. Stack after others.
x = wanted_x;
} else {
// This box does not touch another floating box, go all the way to the first edge.
x = first_edge_of_margin_box(box_state);
// Also, forget all previous boxes floated to this side while since they're no longer relevant.
side_data.boxes.clear();
}
} else {
// We ran out of horizontal space on this "float line", and need to break.
x = first_edge_of_margin_box(box_state);
float lowest_border_edge = 0;
for (auto const& box : side_data.boxes) {
auto const& box_state = m_state.get(box);
lowest_border_edge = max(lowest_border_edge, box_state.border_box_height());
}
side_data.y_offset += lowest_border_edge;
// Also, forget all previous boxes floated to this side while since they're no longer relevant.
side_data.boxes.clear();
}
}
y += side_data.y_offset;
side_data.boxes.append(box);
box_state.offset = Gfx::FloatPoint { x, y };
};
// Next, float to the left and/or right
if (box.computed_values().float_() == CSS::Float::Left) {
float_box(FloatSide::Left, m_left_floats);
} else if (box.computed_values().float_() == CSS::Float::Right) {
float_box(FloatSide::Right, m_right_floats);
}
}
}
Reference in a new issue View git blame Copy permalink