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ladybird/Userland/Libraries/LibWeb/Layout/BlockFormattingContext.cpp
Sam Atkins ce0de4b2b4 LibWeb: Allow LengthPercentage to hold a calculated value 
Most of the time, we cannot resolve a `calc()` expression until we go to
use it. Since any `<length-percentage>` can legally be a `calc
()`, let's store it in `LengthPercentage` rather than make every single
user care about this distinction.
2022-02-04 13:52:02 +01:00

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32 KiB
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/*
* Copyright (c) 2020-2021, 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(BlockContainer& root, FormattingContext* parent)
: FormattingContext(Type::Block, root, parent)
{
}
BlockFormattingContext::~BlockFormattingContext()
{
}
bool BlockFormattingContext::is_initial() const
{
return is<InitialContainingBlock>(root());
}
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 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(box);
if (box.children_are_inline()) {
layout_inline_children(verify_cast<BlockContainer>(box), layout_mode);
} else {
layout_block_level_children(verify_cast<BlockContainer>(box), layout_mode);
}
if (layout_mode == LayoutMode::Default) {
compute_height(box);
box.for_each_child_of_type<Box>([&](auto& child_box) {
if (child_box.is_absolutely_positioned()) {
layout_absolutely_positioned_element(child_box);
}
return IterationDecision::Continue;
});
}
apply_transformations_to_children(box);
}
void BlockFormattingContext::apply_transformations_to_children(Box& 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.resolved_or_zero(child_box).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 untransformed_offset = child_box.effective_offset();
child_box.set_offset(untransformed_offset.x(), untransformed_offset.y() + transform_y_offset);
});
}
void BlockFormattingContext::compute_width(Box& 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);
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& computed_values = box.computed_values();
float width_of_containing_block = box.containing_block()->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_or_zero(box);
const auto padding_right = computed_values.padding().right.resolved(box, width_of_containing_block_as_length).resolved_or_zero(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_or_zero(box);
margin_right = computed_values.margin().right.resolved(box, width_of_containing_block_as_length).resolved_or_zero(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().resolved(box, width_of_containing_block_as_length).resolved_or_auto(box);
// 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().resolved(box, width_of_containing_block_as_length).resolved_or_auto(box);
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().resolved(box, width_of_containing_block_as_length).resolved_or_auto(box);
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);
}
}
box.set_width(used_width.to_px(box));
box.box_model().margin.left = margin_left.to_px(box);
box.box_model().margin.right = margin_right.to_px(box);
box.box_model().border.left = computed_values.border_left().width;
box.box_model().border.right = computed_values.border_right().width;
box.box_model().padding.left = padding_left.to_px(box);
box.box_model().padding.right = padding_right.to_px(box);
}
void BlockFormattingContext::compute_width_for_floating_box(Box& box)
{
// 10.3.5 Floating, non-replaced elements
auto& computed_values = box.computed_values();
float width_of_containing_block = box.containing_block()->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_or_zero(box);
auto margin_right = computed_values.margin().right.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box);
const auto padding_left = computed_values.padding().left.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box);
const auto padding_right = computed_values.padding().right.resolved(box, width_of_containing_block_as_length).resolved_or_zero(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().resolved(box, width_of_containing_block_as_length).resolved_or_auto(box);
// 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);
}
float final_width = width.resolved_or_zero(box).to_px(box);
box.set_width(final_width);
box.box_model().margin.left = margin_left.to_px(box);
box.box_model().margin.right = margin_right.to_px(box);
box.box_model().border.left = computed_values.border_left().width;
box.box_model().border.right = computed_values.border_right().width;
box.box_model().padding.left = padding_left.to_px(box);
box.box_model().padding.right = padding_right.to_px(box);
}
void BlockFormattingContext::compute_width_for_block_level_replaced_element_in_normal_flow(ReplacedBox& box)
{
box.set_width(compute_width_for_replaced_element(box));
}
float BlockFormattingContext::compute_theoretical_height(Box const& box)
{
auto& computed_values = box.computed_values();
auto& containing_block = *box.containing_block();
auto containing_block_height = CSS::Length::make_px(containing_block.height());
auto is_absolute = [](CSS::LengthPercentage const& length_percentage) {
return 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(verify_cast<ReplacedBox>(box));
} else {
if ((box.computed_values().height().is_length() && box.computed_values().height().length().is_undefined_or_auto())
|| (computed_values.height().is_percentage() && !is_absolute(containing_block.computed_values().height()))) {
height = compute_auto_height_for_block_level_element(box, ConsiderFloats::No);
} else {
height = computed_values.height().resolved(box, containing_block_height).resolved_or_auto(box).to_px(box);
}
}
auto specified_max_height = computed_values.max_height().resolved(box, containing_block_height).resolved_or_auto(box);
if (!specified_max_height.is_auto()
&& !(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().resolved(box, containing_block_height).resolved_or_auto(box);
if (!specified_min_height.is_auto()
&& !(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& box)
{
auto& computed_values = box.computed_values();
auto& containing_block = *box.containing_block();
auto width_of_containing_block_as_length = CSS::Length::make_px(containing_block.width());
// First, resolve the top/bottom parts of the surrounding box model.
// FIXME: While negative values are generally allowed for margins, for now just ignore those for height calculation
box.box_model().margin.top = max(computed_values.margin().top.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box).to_px(box), 0);
box.box_model().margin.bottom = max(computed_values.margin().bottom.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box).to_px(box), 0);
box.box_model().border.top = computed_values.border_top().width;
box.box_model().border.bottom = computed_values.border_bottom().width;
box.box_model().padding.top = computed_values.padding().top.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box).to_px(box);
box.box_model().padding.bottom = computed_values.padding().bottom.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box).to_px(box);
auto height = compute_theoretical_height(box);
box.set_height(height);
}
void BlockFormattingContext::compute_position(Box& box)
{
// 9.4.3 Relative positioning
// Once a box has been laid out according to the normal flow or floated, it may be shifted relative to this position.
auto& box_model = box.box_model();
auto& computed_values = box.computed_values();
float width_of_containing_block = box.containing_block()->width();
auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
auto specified_left = computed_values.offset().left.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box);
auto specified_right = computed_values.offset().right.resolved(box, width_of_containing_block_as_length).resolved_or_zero(box);
if (specified_left.is_auto() && specified_right.is_auto()) {
// If both 'left' and 'right' are 'auto' (their initial values), the used values are '0' (i.e., the boxes stay in their original position).
box_model.offset.left = 0;
box_model.offset.right = 0;
} else if (specified_left.is_auto()) {
// If 'left' is 'auto', its used value is minus the value of 'right' (i.e., the boxes move to the left by the value of 'right').
box_model.offset.right = specified_right.to_px(box);
box_model.offset.left = 0 - box_model.offset.right;
} else if (specified_right.is_auto()) {
// If 'right' is specified as 'auto', its used value is minus the value of 'left'.
box_model.offset.left = specified_left.to_px(box);
box_model.offset.right = 0 - box_model.offset.left;
} else {
// If neither 'left' nor 'right' is 'auto', the position is over-constrained, and one of them has to be ignored.
// If the 'direction' property of the containing block is 'ltr', the value of 'left' wins and 'right' becomes -'left'.
// If 'direction' of the containing block is 'rtl', 'right' wins and 'left' is ignored.
// FIXME: Check direction (assuming 'ltr' for now).
box_model.offset.left = specified_left.to_px(box);
box_model.offset.right = 0 - box_model.offset.left;
}
}
void BlockFormattingContext::layout_inline_children(BlockContainer& block_container, LayoutMode layout_mode)
{
InlineFormattingContext context(block_container, *this);
context.run(block_container, layout_mode);
}
void BlockFormattingContext::layout_block_level_children(BlockContainer& block_container, LayoutMode layout_mode)
{
float content_height = 0;
float content_width = 0;
block_container.for_each_child_of_type<Box>([&](Box& child_box) {
if (child_box.is_absolutely_positioned())
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);
(void)layout_inside(child_box, layout_mode);
compute_height(child_box);
if (child_box.computed_values().position() == CSS::Position::Relative)
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, child_box.effective_offset().y() + child_box.height() + child_box.box_model().margin_box().bottom);
content_width = max(content_width, verify_cast<Box>(child_box).width());
return IterationDecision::Continue;
});
if (layout_mode != LayoutMode::Default) {
if (block_container.computed_values().width().is_length() && block_container.computed_values().width().length().is_undefined_or_auto())
block_container.set_width(content_width);
}
}
void BlockFormattingContext::compute_vertical_box_model_metrics(Box& child_box, BlockContainer const& containing_block)
{
auto& box_model = child_box.box_model();
auto const& computed_values = child_box.computed_values();
auto width_of_containing_block = CSS::Length::make_px(containing_block.width());
box_model.margin.top = computed_values.margin().top.resolved(child_box, width_of_containing_block).resolved_or_zero(containing_block).to_px(child_box);
box_model.margin.bottom = computed_values.margin().bottom.resolved(child_box, width_of_containing_block).resolved_or_zero(containing_block).to_px(child_box);
box_model.border.top = computed_values.border_top().width;
box_model.border.bottom = computed_values.border_bottom().width;
box_model.padding.top = computed_values.padding().top.resolved(child_box, width_of_containing_block).resolved_or_zero(containing_block).to_px(child_box);
box_model.padding.bottom = computed_values.padding().bottom.resolved(child_box, width_of_containing_block).resolved_or_zero(containing_block).to_px(child_box);
}
void BlockFormattingContext::place_block_level_element_in_normal_flow_vertically(Box& child_box, BlockContainer const& containing_block)
{
auto& box_model = child_box.box_model();
auto const& computed_values = child_box.computed_values();
compute_vertical_box_model_metrics(child_box, containing_block);
float y = box_model.margin_box().top
+ box_model.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()) {
collapsed_bottom_margin_of_preceding_siblings = max(collapsed_bottom_margin_of_preceding_siblings, relevant_sibling->box_model().margin.bottom);
if (relevant_sibling->border_box_height() > 0)
break;
}
relevant_sibling = relevant_sibling->previous_sibling();
}
if (relevant_sibling) {
y += relevant_sibling->effective_offset().y()
+ relevant_sibling->height()
+ relevant_sibling->box_model().border_box().bottom;
// Collapse top margin with bottom margin of preceding siblings if needed
float my_margin_top = box_model.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& floating_box : float_side.boxes) {
clearance_y = max(clearance_y, floating_box.effective_offset().y() + floating_box.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);
child_box.set_offset(child_box.effective_offset().x(), y);
}
void BlockFormattingContext::place_block_level_element_in_normal_flow_horizontally(Box& child_box, BlockContainer const& containing_block)
{
auto& box_model = child_box.box_model();
float x = 0;
if (containing_block.computed_values().text_align() == CSS::TextAlign::LibwebCenter) {
x = (containing_block.width() / 2) - child_box.width() / 2;
} else {
x = box_model.margin_box().left + box_model.offset.left;
}
child_box.set_offset(x, child_box.effective_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());
icb.build_stacking_context_tree();
icb.set_width(viewport_rect.width());
icb.set_height(viewport_rect.height());
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& child) {
auto child_rect = child.bordered_rect();
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()) {
auto& overflow_data = 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 {
icb.clear_overflow_data();
}
}
void BlockFormattingContext::layout_floating_child(Box& box, BlockContainer const& containing_block)
{
VERIFY(box.is_floating());
compute_width(box);
(void)layout_inside(box, LayoutMode::Default);
compute_height(box);
// 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 = [&](PixelBox const& thing) { return side == FloatSide::Left ? thing.left : thing.right; };
auto second_edge = [&](PixelBox const& thing) { return side == FloatSide::Right ? thing.left : thing.right; };
// Then we float it to the left or right.
float x = box.effective_offset().x();
auto box_in_root_rect = box.margin_box_rect_in_ancestor_coordinate_space(root());
float y_in_root = box_in_root_rect.y();
float y = box.effective_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.box_model().margin_box().left;
else
x = containing_block.width() - box.box_model().margin_box().right - box.width();
side_data.y_offset = 0;
} else {
auto& previous_box = side_data.boxes.last();
auto previous_rect = previous_box.margin_box_rect_in_ancestor_coordinate_space(root());
auto margin_collapsed_with_previous = max(
second_edge(previous_box.box_model().margin),
first_edge(box.box_model().margin));
float wanted_x = 0;
bool fits_on_line = false;
if (side == FloatSide::Left) {
auto previous_right_border_edge = previous_box.effective_offset().x()
+ previous_box.width()
+ previous_box.box_model().padding.right
+ previous_box.box_model().border.right
+ margin_collapsed_with_previous;
wanted_x = previous_right_border_edge + box.box_model().border.left + box.box_model().padding.left;
fits_on_line = (wanted_x + box.width() + box.box_model().padding.right + box.box_model().border.right + box.box_model().margin.right) <= containing_block.width();
} else {
auto previous_left_border_edge = previous_box.effective_offset().x()
- previous_box.width()
- previous_box.box_model().padding.left
- previous_box.box_model().border.left
- margin_collapsed_with_previous;
wanted_x = previous_left_border_edge - box.box_model().border.right - box.box_model().padding.right - box.width();
fits_on_line = (wanted_x - box.box_model().padding.left - box.box_model().border.left - box.box_model().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(box.box_model().margin_box());
// 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(box.box_model().margin_box());
float lowest_border_edge = 0;
for (auto const& box : side_data.boxes)
lowest_border_edge = max(lowest_border_edge, box.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.set_offset(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);
}
}
}
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