/*
* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Dump.h>
#include <LibWeb/Layout/BlockFormattingContext.h>
#include <LibWeb/Layout/Box.h>
#include <LibWeb/Layout/FlexFormattingContext.h>
#include <LibWeb/Layout/FormattingContext.h>
#include <LibWeb/Layout/InlineFormattingContext.h>
#include <LibWeb/Layout/ReplacedBox.h>
#include <LibWeb/Layout/SVGFormattingContext.h>
#include <LibWeb/Layout/SVGSVGBox.h>
#include <LibWeb/Layout/TableBox.h>
#include <LibWeb/Layout/TableCellBox.h>
#include <LibWeb/Layout/TableFormattingContext.h>
namespace Web::Layout {
FormattingContext::FormattingContext(Type type, FormattingState& state, Box const& context_box, FormattingContext* parent)
: m_type(type)
, m_parent(parent)
, m_context_box(context_box)
, m_state(state)
{
}
FormattingContext::~FormattingContext() = default;
bool FormattingContext::creates_block_formatting_context(Box const& box)
{
if (box.is_root_element())
return true;
if (box.is_floating())
return true;
if (box.is_absolutely_positioned())
return true;
if (box.is_inline_block())
return true;
if (is<TableCellBox>(box))
return true;
CSS::Overflow overflow_x = box.computed_values().overflow_x();
if ((overflow_x != CSS::Overflow::Visible) && (overflow_x != CSS::Overflow::Clip))
return true;
CSS::Overflow overflow_y = box.computed_values().overflow_y();
if ((overflow_y != CSS::Overflow::Visible) && (overflow_y != CSS::Overflow::Clip))
return true;
auto display = box.computed_values().display();
if (display.is_flow_root_inside())
return true;
if (box.parent()) {
auto parent_display = box.parent()->computed_values().display();
if (parent_display.is_flex_inside()) {
// FIXME: Flex items (direct children of the element with display: flex or inline-flex) if they are neither flex nor grid nor table containers themselves.
if (!display.is_flex_inside())
return true;
}
}
// FIXME: table-caption
// FIXME: anonymous table cells
// FIXME: Elements with contain: layout, content, or paint.
// FIXME: grid
// FIXME: multicol
// FIXME: column-span: all
return false;
}
OwnPtr<FormattingContext> FormattingContext::create_independent_formatting_context_if_needed(FormattingState& state, Box const& child_box)
{
if (child_box.is_replaced_box() && !child_box.can_have_children()) {
// NOTE: This is a bit strange.
// Basically, we create a pretend formatting context for replaced elements that does nothing.
// This allows other formatting contexts to treat them like elements that actually need inside layout
// without having separate code to handle replaced elements.
// FIXME: Find a better abstraction for this.
struct ReplacedFormattingContext : public FormattingContext {
ReplacedFormattingContext(FormattingState& state, Box const& box)
: FormattingContext(Type::Block, state, box)
{
}
virtual void run(Box const&, LayoutMode) override { }
};
return make<ReplacedFormattingContext>(state, child_box);
}
if (!child_box.can_have_children())
return {};
auto child_display = child_box.computed_values().display();
if (is<SVGSVGBox>(child_box))
return make<SVGFormattingContext>(state, child_box, this);
if (child_display.is_flex_inside())
return make<FlexFormattingContext>(state, child_box, this);
if (creates_block_formatting_context(child_box))
return make<BlockFormattingContext>(state, verify_cast<BlockContainer>(child_box), this);
if (child_display.is_table_inside())
return make<TableFormattingContext>(state, verify_cast<TableBox>(child_box), this);
VERIFY(is_block_formatting_context());
if (child_box.children_are_inline())
return make<InlineFormattingContext>(state, verify_cast<BlockContainer>(child_box), static_cast<BlockFormattingContext&>(*this));
// The child box is a block container that doesn't create its own BFC.
// It will be formatted by this BFC.
if (!child_display.is_flow_inside()) {
dbgln("FIXME: Child box doesn't create BFC, but inside is also not flow! display={}", child_display.to_string());
// HACK: Instead of crashing, create a dummy formatting context that does nothing.
// FIXME: Remove this once it's no longer needed. It currently swallows problem with standalone
// table-related boxes that don't get fixed up by CSS anonymous table box generation.
struct DummyFormattingContext : public FormattingContext {
DummyFormattingContext(FormattingState& state, Box const& box)
: FormattingContext(Type::Block, state, box)
{
}
virtual void run(Box const&, LayoutMode) override { }
};
return make<DummyFormattingContext>(state, child_box);
}
VERIFY(child_box.is_block_container());
VERIFY(child_display.is_flow_inside());
return {};
}
OwnPtr<FormattingContext> FormattingContext::layout_inside(Box const& child_box, LayoutMode layout_mode)
{
if (!child_box.can_have_children())
return {};
auto independent_formatting_context = create_independent_formatting_context_if_needed(m_state, child_box);
if (independent_formatting_context)
independent_formatting_context->run(child_box, layout_mode);
else
run(child_box, layout_mode);
return independent_formatting_context;
}
float FormattingContext::greatest_child_width(Box const& box)
{
float max_width = 0;
if (box.children_are_inline()) {
for (auto& line_box : m_state.get(verify_cast<BlockContainer>(box)).line_boxes) {
max_width = max(max_width, line_box.width());
}
} else {
box.for_each_child_of_type<Box>([&](auto& child) {
max_width = max(max_width, m_state.get(child).border_box_width());
});
}
return max_width;
}
FormattingContext::ShrinkToFitResult FormattingContext::calculate_shrink_to_fit_widths(Box const& box)
{
auto [min_content, max_content] = calculate_intrinsic_sizes(box);
return {
.preferred_width = max_content.width(),
.preferred_minimum_width = min_content.width(),
};
}
static Gfx::FloatSize solve_replaced_size_constraint(FormattingState const& state, float w, float h, ReplacedBox const& box)
{
// 10.4 Minimum and maximum widths: 'min-width' and 'max-width'
auto const& containing_block = *box.containing_block();
auto const& containing_block_state = state.get(containing_block);
auto width_of_containing_block = CSS::Length::make_px(containing_block_state.content_width);
auto height_of_containing_block = CSS::Length::make_px(containing_block_state.content_height);
auto specified_min_width = box.computed_values().min_width().has_value() ? box.computed_values().min_width()->resolved(box, width_of_containing_block).to_px(box) : 0;
auto specified_max_width = box.computed_values().max_width().has_value() ? box.computed_values().max_width()->resolved(box, width_of_containing_block).to_px(box) : w;
auto specified_min_height = box.computed_values().min_height().has_value() ? box.computed_values().min_height()->resolved(box, height_of_containing_block).to_px(box) : 0;
auto specified_max_height = box.computed_values().max_height().has_value() ? box.computed_values().max_height()->resolved(box, height_of_containing_block).to_px(box) : h;
auto min_width = min(specified_min_width, specified_max_width);
auto max_width = max(specified_min_width, specified_max_width);
auto min_height = min(specified_min_height, specified_max_height);
auto max_height = max(specified_min_height, specified_max_height);
if (w > max_width)
return { w, max(max_width * h / w, min_height) };
if (w < min_width)
return { max_width, min(min_width * h / w, max_height) };
if (h > max_height)
return { max(max_height * w / h, min_width), max_height };
if (h < min_height)
return { min(min_height * w / h, max_width), min_height };
if ((w > max_width && h > max_height) && (max_width / w < max_height / h))
return { max_width, max(min_height, max_width * h / w) };
if ((w > max_width && h > max_height) && (max_width / w > max_height / h))
return { max(min_width, max_height * w / h), max_height };
if ((w < min_width && h < min_height) && (min_width / w < min_height / h))
return { min(max_width, min_height * w / h), min_height };
if ((w < min_width && h < min_height) && (min_width / w > min_height / h))
return { min_width, min(max_height, min_width * h / w) };
if (w < min_width && h > max_height)
return { min_width, max_height };
if (w > max_width && h < min_height)
return { max_width, min_height };
return { w, h };
}
float FormattingContext::compute_auto_height_for_block_level_element(FormattingState const& state, Box const& box)
{
if (creates_block_formatting_context(box))
return compute_auto_height_for_block_formatting_context_root(state, verify_cast<BlockContainer>(box));
auto const& box_state = state.get(box);
auto display = box.computed_values().display();
if (display.is_flex_inside())
return box_state.content_height;
// https://www.w3.org/TR/CSS22/visudet.html#normal-block
// 10.6.3 Block-level non-replaced elements in normal flow when 'overflow' computes to 'visible'
// The element's height is the distance from its top content edge to the first applicable of the following:
// 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
if (box.children_are_inline() && !box_state.line_boxes.is_empty())
return box_state.line_boxes.last().bottom();
// 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin does not collapse with the element's bottom margin
// FIXME: 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
if (!box.children_are_inline()) {
for (auto* child_box = box.last_child_of_type<Box>(); child_box; child_box = child_box->previous_sibling_of_type<Box>()) {
if (child_box->is_absolutely_positioned() || child_box->is_floating())
continue;
// FIXME: This is hack. If the last child is a list-item marker box, we ignore it for purposes of height calculation.
// Perhaps markers should not be considered in-flow(?) Perhaps they should always be the first child of the list-item
// box instead of the last child.
if (child_box->is_list_item_marker_box())
continue;
auto const& child_box_state = state.get(*child_box);
// Ignore anonymous block containers with no lines. These don't count as in-flow block boxes.
if (child_box->is_anonymous() && child_box->is_block_container() && child_box_state.line_boxes.is_empty())
continue;
// FIXME: Handle margin collapsing.
return max(0, child_box_state.offset.y() + child_box_state.content_height + child_box_state.margin_box_bottom());
}
}
// 4. zero, otherwise
return 0;
}
// https://www.w3.org/TR/CSS22/visudet.html#root-height
float FormattingContext::compute_auto_height_for_block_formatting_context_root(FormattingState const& state, BlockContainer const& root)
{
// 10.6.7 'Auto' heights for block formatting context roots
Optional<float> top;
Optional<float> bottom;
if (root.children_are_inline()) {
// If it only has inline-level children, the height is the distance between
// the top content edge and the bottom of the bottommost line box.
auto const& line_boxes = state.get(root).line_boxes;
top = 0;
if (!line_boxes.is_empty())
bottom = line_boxes.last().bottom();
} else {
// If it has block-level children, the height is the distance between
// the top margin-edge of the topmost block-level child box
// and the bottom margin-edge of the bottommost block-level child box.
root.for_each_child_of_type<Box>([&](Layout::Box& child_box) {
// Absolutely positioned children are ignored,
// and relatively positioned boxes are considered without their offset.
// Note that the child box may be an anonymous block box.
if (child_box.is_absolutely_positioned())
return IterationDecision::Continue;
// FIXME: This doesn't look right.
if ((root.computed_values().overflow_y() == CSS::Overflow::Visible) && child_box.is_floating())
return IterationDecision::Continue;
auto const& child_box_state = state.get(child_box);
float child_box_top = child_box_state.offset.y() - child_box_state.margin_box_top();
float child_box_bottom = child_box_state.offset.y() + child_box_state.content_height + child_box_state.margin_box_bottom();
if (!top.has_value() || child_box_top < top.value())
top = child_box_top;
if (!bottom.has_value() || child_box_bottom > bottom.value())
bottom = child_box_bottom;
return IterationDecision::Continue;
});
}
// In addition, if the element has any floating descendants
// whose bottom margin edge is below the element's bottom content edge,
// then the height is increased to include those edges.
root.for_each_child_of_type<Box>([&](Layout::Box& child_box) {
if (!child_box.is_floating())
return IterationDecision::Continue;
auto const& child_box_state = state.get(child_box);
float child_box_bottom = child_box_state.offset.y() + child_box_state.content_height + child_box_state.margin_box_bottom();
if (!bottom.has_value() || child_box_bottom > bottom.value())
bottom = child_box_bottom;
return IterationDecision::Continue;
});
return max(0, bottom.value_or(0) - top.value_or(0));
}
// 10.3.2 Inline, replaced elements, https://www.w3.org/TR/CSS22/visudet.html#inline-replaced-width
float FormattingContext::tentative_width_for_replaced_element(FormattingState const& state, ReplacedBox const& box, CSS::Length const& computed_width)
{
auto const& containing_block = *box.containing_block();
auto height_of_containing_block = CSS::Length::make_px(state.get(containing_block).content_height);
auto computed_height = box.computed_values().height().has_value() ? box.computed_values().height()->resolved(box, height_of_containing_block).resolved(box) : CSS::Length::make_auto();
float used_width = computed_width.to_px(box);
// If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width,
// then that intrinsic width is the used value of 'width'.
if (computed_height.is_auto() && computed_width.is_auto() && box.has_intrinsic_width())
return box.intrinsic_width().value();
// If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width,
// but does have an intrinsic height and intrinsic ratio;
// or if 'width' has a computed value of 'auto',
// 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value of 'width' is:
//
// (used height) * (intrinsic ratio)
if ((computed_height.is_auto() && computed_width.is_auto() && !box.has_intrinsic_width() && box.has_intrinsic_height() && box.has_intrinsic_aspect_ratio())
|| (computed_width.is_auto() && box.has_intrinsic_aspect_ratio())) {
return compute_height_for_replaced_element(state, box) * box.intrinsic_aspect_ratio().value();
}
// If 'height' and 'width' both have computed values of 'auto' and the element has an intrinsic ratio but no intrinsic height or width,
// then the used value of 'width' is undefined in CSS 2.2. However, it is suggested that, if the containing block's width does not itself
// depend on the replaced element's width, then the used value of 'width' is calculated from the constraint equation used for block-level,
// non-replaced elements in normal flow.
// Otherwise, if 'width' has a computed value of 'auto', and the element has an intrinsic width, then that intrinsic width is the used value of 'width'.
if (computed_width.is_auto() && box.has_intrinsic_width())
return box.intrinsic_width().value();
// Otherwise, if 'width' has a computed value of 'auto', but none of the conditions above are met, then the used value of 'width' becomes 300px.
// If 300px is too wide to fit the device, UAs should use the width of the largest rectangle that has a 2:1 ratio and fits the device instead.
if (computed_width.is_auto())
return 300;
return used_width;
}
void FormattingContext::compute_width_for_absolutely_positioned_element(Box const& box)
{
if (is<ReplacedBox>(box))
compute_width_for_absolutely_positioned_replaced_element(verify_cast<ReplacedBox>(box));
else
compute_width_for_absolutely_positioned_non_replaced_element(box);
}
void FormattingContext::compute_height_for_absolutely_positioned_element(Box const& box)
{
if (is<ReplacedBox>(box))
compute_height_for_absolutely_positioned_replaced_element(verify_cast<ReplacedBox>(box));
else
compute_height_for_absolutely_positioned_non_replaced_element(box);
}
float FormattingContext::compute_width_for_replaced_element(FormattingState const& state, ReplacedBox const& box)
{
// 10.3.4 Block-level, replaced elements in normal flow...
// 10.3.2 Inline, replaced elements
auto zero_value = CSS::Length::make_px(0);
auto const& containing_block = *box.containing_block();
auto width_of_containing_block = CSS::Length::make_px(state.get(containing_block).content_width);
auto margin_left = box.computed_values().margin().left.resolved(box, width_of_containing_block).resolved(box);
auto margin_right = box.computed_values().margin().right.resolved(box, width_of_containing_block).resolved(box);
// 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;
auto specified_width = box.computed_values().width().has_value() ? box.computed_values().width()->resolved(box, width_of_containing_block).resolved(box) : CSS::Length::make_auto();
// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
auto used_width = tentative_width_for_replaced_element(state, box, 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 = box.computed_values().max_width().has_value() ? box.computed_values().max_width()->resolved(box, width_of_containing_block).resolved(box) : CSS::Length::make_auto();
if (!specified_max_width.is_auto()) {
if (used_width > specified_max_width.to_px(box)) {
used_width = tentative_width_for_replaced_element(state, box, 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 = box.computed_values().min_width().has_value() ? box.computed_values().min_width()->resolved(box, width_of_containing_block).resolved(box) : CSS::Length::make_auto();
if (!specified_min_width.is_auto()) {
if (used_width < specified_min_width.to_px(box)) {
used_width = tentative_width_for_replaced_element(state, box, specified_min_width);
}
}
return used_width;
}
// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block' replaced elements in normal flow and floating replaced elements
// https://www.w3.org/TR/CSS22/visudet.html#inline-replaced-height
float FormattingContext::tentative_height_for_replaced_element(FormattingState const& state, ReplacedBox const& box, CSS::Length const& computed_height)
{
auto const& containing_block = *box.containing_block();
auto width_of_containing_block = CSS::Length::make_px(state.get(containing_block).content_width);
auto computed_width = box.computed_values().width().has_value() ? box.computed_values().width()->resolved(box, width_of_containing_block).resolved(box) : CSS::Length::make_auto();
// If 'height' and 'width' both have computed values of 'auto' and the element also has
// an intrinsic height, then that intrinsic height is the used value of 'height'.
if (computed_width.is_auto() && computed_height.is_auto() && box.has_intrinsic_height())
return box.intrinsic_height().value();
// Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic ratio then the used value of 'height' is:
//
// (used width) / (intrinsic ratio)
if (computed_height.is_auto() && box.has_intrinsic_aspect_ratio())
return compute_width_for_replaced_element(state, box) / box.intrinsic_aspect_ratio().value();
// Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic height, then that intrinsic height is the used value of 'height'.
if (computed_height.is_auto() && box.has_intrinsic_height())
return box.intrinsic_height().value();
// Otherwise, if 'height' has a computed value of 'auto', but none of the conditions above are met,
// then the used value of 'height' must be set to the height of the largest rectangle that has a 2:1 ratio, has a height not greater than 150px,
// and has a width not greater than the device width.
if (computed_height.is_auto())
return 150;
return computed_height.to_px(box);
}
float FormattingContext::compute_height_for_replaced_element(FormattingState const& state, ReplacedBox const& box)
{
// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow,
// 'inline-block' replaced elements in normal flow and floating replaced elements
auto const& containing_block = *box.containing_block();
auto const& containing_block_state = state.get(containing_block);
auto width_of_containing_block = CSS::Length::make_px(containing_block_state.content_width);
auto height_of_containing_block = CSS::Length::make_px(containing_block_state.content_height);
auto specified_width = box.computed_values().width().has_value() ? box.computed_values().width()->resolved(box, width_of_containing_block).resolved(box) : CSS::Length::make_auto();
auto specified_height = box.computed_values().height().has_value() ? box.computed_values().height()->resolved(box, height_of_containing_block).resolved(box) : CSS::Length::make_auto();
float used_height = tentative_height_for_replaced_element(state, box, specified_height);
if (specified_width.is_auto() && specified_height.is_auto() && box.has_intrinsic_aspect_ratio()) {
float w = tentative_width_for_replaced_element(state, box, specified_width);
float h = used_height;
used_height = solve_replaced_size_constraint(state, w, h, box).height();
}
return used_height;
}
void FormattingContext::compute_width_for_absolutely_positioned_non_replaced_element(Box const& box)
{
auto& containing_block_state = m_state.get(*box.containing_block());
auto& box_state = m_state.get_mutable(box);
auto width_of_containing_block = CSS::Length::make_px(containing_block_state.content_width);
auto& computed_values = box.computed_values();
auto zero_value = CSS::Length::make_px(0);
auto margin_left = CSS::Length::make_auto();
auto margin_right = CSS::Length::make_auto();
auto const border_left = computed_values.border_left().width;
auto const border_right = computed_values.border_right().width;
auto const padding_left = computed_values.padding().left.resolved(box, width_of_containing_block).to_px(box);
auto const padding_right = computed_values.padding().right.resolved(box, width_of_containing_block).to_px(box);
auto try_compute_width = [&](auto const& a_width) {
margin_left = computed_values.margin().left.resolved(box, width_of_containing_block).resolved(box);
margin_right = computed_values.margin().right.resolved(box, width_of_containing_block).resolved(box);
auto left = computed_values.inset().left.resolved(box, width_of_containing_block).resolved(box);
auto right = computed_values.inset().right.resolved(box, width_of_containing_block).resolved(box);
auto width = a_width;
auto solve_for_left = [&] {
return CSS::Length(containing_block_state.content_width - margin_left.to_px(box) - border_left - padding_left - width.to_px(box) - padding_right - border_right - margin_right.to_px(box) - right.to_px(box), CSS::Length::Type::Px);
};
auto solve_for_width = [&] {
return CSS::Length(containing_block_state.content_width - left.to_px(box) - margin_left.to_px(box) - border_left - padding_left - padding_right - border_right - margin_right.to_px(box) - right.to_px(box), CSS::Length::Type::Px);
};
auto solve_for_right = [&] {
return CSS::Length(containing_block_state.content_width - left.to_px(box) - margin_left.to_px(box) - border_left - padding_left - width.to_px(box) - padding_right - border_right - margin_right.to_px(box), CSS::Length::Type::Px);
};
// If all three of 'left', 'width', and 'right' are 'auto':
if (left.is_auto() && width.is_auto() && right.is_auto()) {
// First set any 'auto' values for 'margin-left' and 'margin-right' to 0.
if (margin_left.is_auto())
margin_left = CSS::Length::make_px(0);
if (margin_right.is_auto())
margin_right = CSS::Length::make_px(0);
// Then, if the 'direction' property of the element establishing the static-position containing block
// is 'ltr' set 'left' to the static position and apply rule number three below;
// otherwise, set 'right' to the static position and apply rule number one below.
// FIXME: This is very hackish.
left = CSS::Length::make_px(0);
goto Rule3;
}
if (!left.is_auto() && !width.is_auto() && !right.is_auto()) {
// FIXME: This should be solved in a more complicated way.
return width;
}
if (margin_left.is_auto())
margin_left = CSS::Length::make_px(0);
if (margin_right.is_auto())
margin_right = CSS::Length::make_px(0);
// 1. 'left' and 'width' are 'auto' and 'right' is not 'auto',
// then the width is shrink-to-fit. Then solve for 'left'
if (left.is_auto() && width.is_auto() && !right.is_auto()) {
auto result = calculate_shrink_to_fit_widths(box);
solve_for_left();
auto available_width = solve_for_width();
width = CSS::Length(min(max(result.preferred_minimum_width, available_width.to_px(box)), result.preferred_width), CSS::Length::Type::Px);
}
// 2. 'left' and 'right' are 'auto' and 'width' is not 'auto',
// then if the 'direction' property of the element establishing
// the static-position containing block is 'ltr' set 'left'
// to the static position, otherwise set 'right' to the static position.
// Then solve for 'left' (if 'direction is 'rtl') or 'right' (if 'direction' is 'ltr').
else if (left.is_auto() && right.is_auto() && !width.is_auto()) {
// FIXME: Check direction
// FIXME: Use the static-position containing block
left = zero_value;
right = solve_for_right();
}
// 3. 'width' and 'right' are 'auto' and 'left' is not 'auto',
// then the width is shrink-to-fit. Then solve for 'right'
else if (width.is_auto() && right.is_auto() && !left.is_auto()) {
Rule3:
auto result = calculate_shrink_to_fit_widths(box);
auto available_width = solve_for_width();
width = CSS::Length(min(max(result.preferred_minimum_width, available_width.to_px(box)), result.preferred_width), CSS::Length::Type::Px);
right = solve_for_right();
}
// 4. 'left' is 'auto', 'width' and 'right' are not 'auto', then solve for 'left'
else if (left.is_auto() && !width.is_auto() && !right.is_auto()) {
left = solve_for_left();
}
// 5. 'width' is 'auto', 'left' and 'right' are not 'auto', then solve for 'width'
else if (width.is_auto() && !left.is_auto() && !right.is_auto()) {
width = solve_for_width();
}
// 6. 'right' is 'auto', 'left' and 'width' are not 'auto', then solve for 'right'
else if (right.is_auto() && !left.is_auto() && !width.is_auto()) {
right = solve_for_right();
}
return width;
};
auto specified_width = computed_values.width().has_value() ? computed_values.width()->resolved(box, width_of_containing_block).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).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).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);
}
}
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 = border_left;
box_state.border_right = border_right;
box_state.padding_left = padding_left;
box_state.padding_right = padding_right;
}
void FormattingContext::compute_width_for_absolutely_positioned_replaced_element(ReplacedBox const& box)
{
// 10.3.8 Absolutely positioned, replaced elements
// The used value of 'width' is determined as for inline replaced elements.
// FIXME: This const_cast is gross.
const_cast<ReplacedBox&>(box).prepare_for_replaced_layout();
m_state.get_mutable(box).content_width = compute_width_for_replaced_element(m_state, box);
}
// https://www.w3.org/TR/CSS22/visudet.html#abs-non-replaced-height
void FormattingContext::compute_height_for_absolutely_positioned_non_replaced_element(Box const& box)
{
// 10.6.4 Absolutely positioned, non-replaced elements
// FIXME: The section below is partly on-spec, partly ad-hoc.
auto& computed_values = box.computed_values();
auto const& containing_block = *box.containing_block();
auto const& containing_block_state = m_state.get(containing_block);
auto& box_state = m_state.get_mutable(box);
auto width_of_containing_block = CSS::Length::make_px(containing_block_state.content_width);
auto height_of_containing_block = CSS::Length::make_px(containing_block_state.content_height);
CSS::Length specified_top = computed_values.inset().top.resolved(box, height_of_containing_block).resolved(box);
CSS::Length specified_bottom = computed_values.inset().bottom.resolved(box, height_of_containing_block).resolved(box);
CSS::Length specified_height = CSS::Length::make_auto();
if (computed_values.height().has_value() && computed_values.height()->is_percentage()
&& !(containing_block.computed_values().height().has_value() && containing_block.computed_values().height()->is_length() && containing_block.computed_values().height()->length().is_absolute())) {
// specified_height is already auto
} else {
specified_height = computed_values.height().has_value() ? computed_values.height()->resolved(box, height_of_containing_block).resolved(box) : CSS::Length::make_auto();
}
auto specified_max_height = computed_values.max_height().has_value() ? computed_values.max_height()->resolved(box, height_of_containing_block).resolved(box) : CSS::Length::make_auto();
auto specified_min_height = computed_values.min_height().has_value() ? computed_values.min_height()->resolved(box, height_of_containing_block).resolved(box) : CSS::Length::make_auto();
box_state.margin_top = computed_values.margin().top.resolved(box, width_of_containing_block).to_px(box);
box_state.margin_bottom = computed_values.margin().bottom.resolved(box, width_of_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).to_px(box);
box_state.padding_bottom = computed_values.padding().bottom.resolved(box, width_of_containing_block).to_px(box);
if (specified_height.is_auto() && specified_top.is_auto() && specified_bottom.is_auto()) {
specified_height = CSS::Length(compute_auto_height_for_block_level_element(m_state, box), CSS::Length::Type::Px);
}
else if (specified_height.is_auto() && !specified_top.is_auto() && specified_bottom.is_auto()) {
specified_height = CSS::Length(compute_auto_height_for_block_level_element(m_state, box), CSS::Length::Type::Px);
box_state.inset_bottom = containing_block_state.content_height - specified_height.to_px(box) - specified_top.to_px(box) - box_state.margin_top - box_state.padding_top - box_state.border_top - box_state.margin_bottom - box_state.padding_bottom - box_state.border_bottom;
}
else if (specified_height.is_auto() && !specified_top.is_auto() && !specified_bottom.is_auto()) {
specified_height = CSS::Length(containing_block_state.content_height - specified_top.to_px(box) - box_state.margin_top - box_state.padding_top - box_state.border_top - specified_bottom.to_px(box) - box_state.margin_bottom - box_state.padding_bottom - box_state.border_bottom, CSS::Length::Type::Px);
}
if (!specified_height.is_auto()) {
float used_height = specified_height.to_px(box);
if (!specified_max_height.is_auto())
used_height = min(used_height, specified_max_height.to_px(box));
if (!specified_min_height.is_auto())
used_height = max(used_height, specified_min_height.to_px(box));
box_state.content_height = used_height;
}
}
void FormattingContext::layout_absolutely_positioned_element(Box const& box)
{
auto const& containing_block_state = m_state.get(*box.containing_block());
auto width_of_containing_block = CSS::Length::make_px(containing_block_state.content_width);
auto height_of_containing_block = CSS::Length::make_px(containing_block_state.content_height);
auto& box_state = m_state.get_mutable(box);
auto specified_width = box.computed_values().width().has_value() ? box.computed_values().width()->resolved(box, width_of_containing_block).resolved(box) : CSS::Length::make_auto();
compute_width_for_absolutely_positioned_element(box);
auto independent_formatting_context = layout_inside(box, LayoutMode::Normal);
compute_height_for_absolutely_positioned_element(box);
box_state.margin_left = box.computed_values().margin().left.resolved(box, width_of_containing_block).to_px(box);
box_state.margin_top = box.computed_values().margin().top.resolved(box, height_of_containing_block).to_px(box);
box_state.margin_right = box.computed_values().margin().right.resolved(box, width_of_containing_block).to_px(box);
box_state.margin_bottom = box.computed_values().margin().bottom.resolved(box, height_of_containing_block).to_px(box);
box_state.border_left = box.computed_values().border_left().width;
box_state.border_right = box.computed_values().border_right().width;
box_state.border_top = box.computed_values().border_top().width;
box_state.border_bottom = box.computed_values().border_bottom().width;
box_state.inset_left = box.computed_values().inset().left.resolved(box, width_of_containing_block).to_px(box);
box_state.inset_top = box.computed_values().inset().top.resolved(box, height_of_containing_block).to_px(box);
box_state.inset_right = box.computed_values().inset().right.resolved(box, width_of_containing_block).to_px(box);
box_state.inset_bottom = box.computed_values().inset().bottom.resolved(box, height_of_containing_block).to_px(box);
auto is_auto = [](auto const& length_percentage) {
return length_percentage.is_length() && length_percentage.length().is_auto();
};
if (is_auto(box.computed_values().inset().left) && specified_width.is_auto() && is_auto(box.computed_values().inset().right)) {
if (is_auto(box.computed_values().margin().left))
box_state.margin_left = 0;
if (is_auto(box.computed_values().margin().right))
box_state.margin_right = 0;
}
Gfx::FloatPoint used_offset;
if (!is_auto(box.computed_values().inset().left)) {
float x_offset = box_state.inset_left
+ box_state.border_box_left();
used_offset.set_x(x_offset + box_state.margin_left);
} else if (!is_auto(box.computed_values().inset().right)) {
float x_offset = 0
- box_state.inset_right
- box_state.border_box_right();
used_offset.set_x(containing_block_state.content_width + x_offset - box_state.content_width - box_state.margin_right);
} else {
float x_offset = box_state.margin_box_left();
used_offset.set_x(x_offset);
}
if (!is_auto(box.computed_values().inset().top)) {
float y_offset = box_state.inset_top
+ box_state.border_box_top();
used_offset.set_y(y_offset + box_state.margin_top);
} else if (!is_auto(box.computed_values().inset().bottom)) {
float y_offset = 0
- box_state.inset_bottom
- box_state.border_box_bottom();
used_offset.set_y(containing_block_state.content_height + y_offset - box_state.content_height - box_state.margin_bottom);
} else {
float y_offset = box_state.margin_box_top();
used_offset.set_y(y_offset);
}
box_state.offset = used_offset;
if (independent_formatting_context)
independent_formatting_context->parent_context_did_dimension_child_root_box();
}
void FormattingContext::compute_height_for_absolutely_positioned_replaced_element(ReplacedBox const& box)
{
// 10.6.5 Absolutely positioned, replaced elements
// The used value of 'height' is determined as for inline replaced elements.
m_state.get_mutable(box).content_height = compute_height_for_replaced_element(m_state, box);
}
// https://www.w3.org/TR/css-position-3/#relpos-insets
void FormattingContext::compute_inset(Box const& box)
{
if (box.computed_values().position() != CSS::Position::Relative)
return;
auto resolve_two_opposing_insets = [&](CSS::LengthPercentage const& computed_start, CSS::LengthPercentage const& computed_end, float& used_start, float& used_end, float reference_for_percentage) {
auto resolved_first = computed_start.resolved(box, CSS::Length::make_px(reference_for_percentage)).resolved(box);
auto resolved_second = computed_end.resolved(box, CSS::Length::make_px(reference_for_percentage)).resolved(box);
if (resolved_first.is_auto() && resolved_second.is_auto()) {
// If opposing inset properties in an axis both compute to auto (their initial values),
// their used values are zero (i.e., the boxes stay in their original position in that axis).
used_start = 0;
used_end = 0;
} else if (resolved_first.is_auto() || resolved_second.is_auto()) {
// If only one is auto, its used value becomes the negation of the other, and the box is shifted by the specified amount.
if (resolved_first.is_auto()) {
used_end = resolved_second.to_px(box);
used_start = 0 - used_end;
} else {
used_start = resolved_first.to_px(box);
used_end = 0 - used_start;
}
} else {
// If neither is auto, the position is over-constrained; (with respect to the writing mode of its containing block)
// the computed end side value is ignored, and its used value becomes the negation of the start side.
used_start = resolved_first.to_px(box);
used_end = 0 - used_start;
}
};
auto& box_state = m_state.get_mutable(box);
auto const& computed_values = box.computed_values();
auto const& containing_block_state = m_state.get(*box.containing_block());
// FIXME: Respect the containing block's writing-mode.
resolve_two_opposing_insets(computed_values.inset().left, computed_values.inset().right, box_state.inset_left, box_state.inset_right, containing_block_state.content_width);
resolve_two_opposing_insets(computed_values.inset().top, computed_values.inset().bottom, box_state.inset_top, box_state.inset_bottom, containing_block_state.content_height);
}
FormattingState::IntrinsicSizes FormattingContext::calculate_intrinsic_sizes(Layout::Box const& box) const
{
// FIXME: This should handle replaced elements with "native" intrinsic size properly!
if (box.has_intrinsic_width() && box.has_intrinsic_height()) {
auto const& replaced_box = static_cast<ReplacedBox const&>(box);
Gfx::FloatSize size { replaced_box.intrinsic_width().value_or(0), replaced_box.intrinsic_height().value_or(0) };
return FormattingState::IntrinsicSizes {
.min_content_size = size,
.max_content_size = size,
};
}
auto& root_state = m_state.m_root;
// If we have cached intrinsic sizes for this box, use them.
auto it = root_state.intrinsic_sizes.find(&box);
if (it != root_state.intrinsic_sizes.end())
return it->value;
// Nothing cached, perform two throwaway layouts to determine the intrinsic sizes.
FormattingState::IntrinsicSizes cached_box_sizes;
auto const& containing_block = *box.containing_block();
{
FormattingState throwaway_state(&m_state);
auto& containing_block_state = throwaway_state.get_mutable(containing_block);
containing_block_state.content_width = INFINITY;
containing_block_state.content_height = INFINITY;
auto independent_formatting_context = const_cast<FormattingContext*>(this)->create_independent_formatting_context_if_needed(throwaway_state, box);
VERIFY(independent_formatting_context);
independent_formatting_context->run(box, LayoutMode::MaxContent);
if (independent_formatting_context->type() == FormattingContext::Type::Flex) {
auto const& box_state = throwaway_state.get(box);
cached_box_sizes.max_content_size = { box_state.content_width, box_state.content_height };
} else {
cached_box_sizes.max_content_size.set_width(independent_formatting_context->greatest_child_width(box));
cached_box_sizes.max_content_size.set_height(calculate_auto_height(throwaway_state, box));
}
}
{
FormattingState throwaway_state(&m_state);
auto& containing_block_state = throwaway_state.get_mutable(containing_block);
containing_block_state.content_width = 0;
containing_block_state.content_height = 0;
auto independent_formatting_context = const_cast<FormattingContext*>(this)->create_independent_formatting_context_if_needed(throwaway_state, box);
VERIFY(independent_formatting_context);
independent_formatting_context->run(box, LayoutMode::MinContent);
if (independent_formatting_context->type() == FormattingContext::Type::Flex) {
auto const& box_state = throwaway_state.get(box);
cached_box_sizes.min_content_size = { box_state.content_width, box_state.content_height };
} else {
cached_box_sizes.min_content_size.set_width(independent_formatting_context->greatest_child_width(box));
cached_box_sizes.min_content_size.set_height(calculate_auto_height(throwaway_state, box));
}
}
if (cached_box_sizes.min_content_size.width() > cached_box_sizes.max_content_size.width()) {
float tmp = cached_box_sizes.min_content_size.width();
cached_box_sizes.min_content_size.set_width(cached_box_sizes.max_content_size.width());
cached_box_sizes.max_content_size.set_width(tmp);
}
if (cached_box_sizes.min_content_size.height() > cached_box_sizes.max_content_size.height()) {
float tmp = cached_box_sizes.min_content_size.height();
cached_box_sizes.min_content_size.set_height(cached_box_sizes.max_content_size.height());
cached_box_sizes.max_content_size.set_height(tmp);
}
root_state.intrinsic_sizes.set(&box, cached_box_sizes);
return cached_box_sizes;
}
FormattingContext::MinAndMaxContentSize FormattingContext::calculate_min_and_max_content_width(Layout::Box const& box) const
{
auto const& sizes = calculate_intrinsic_sizes(box);
return { sizes.min_content_size.width(), sizes.max_content_size.width() };
}
FormattingContext::MinAndMaxContentSize FormattingContext::calculate_min_and_max_content_height(Layout::Box const& box) const
{
auto const& sizes = calculate_intrinsic_sizes(box);
return { sizes.min_content_size.height(), sizes.max_content_size.height() };
}
float FormattingContext::calculate_fit_content_size(float min_content_size, float max_content_size, Optional<float> available_space) const
{
// If the available space in a given axis is definite, equal to clamp(min-content size, stretch-fit size, max-content size)
// (i.e. max(min-content size, min(max-content size, stretch-fit size))).
if (available_space.has_value()) {
// FIXME: Compute the real stretch-fit size.
auto stretch_fit_size = *available_space;
auto s = max(min_content_size, min(max_content_size, stretch_fit_size));
return s;
}
// FIXME: When sizing under a min-content constraint, equal to the min-content size.
// Otherwise, equal to the max-content size in that axis.
return max_content_size;
}
float FormattingContext::calculate_fit_content_width(Layout::Box const& box, Optional<float> available_space) const
{
auto [min_content_size, max_content_size] = calculate_min_and_max_content_width(box);
return calculate_fit_content_size(min_content_size, max_content_size, available_space);
}
float FormattingContext::calculate_fit_content_height(Layout::Box const& box, Optional<float> available_space) const
{
auto [min_content_size, max_content_size] = calculate_min_and_max_content_height(box);
return calculate_fit_content_size(min_content_size, max_content_size, available_space);
}
float FormattingContext::calculate_auto_height(FormattingState const& state, Box const& box)
{
if (is<ReplacedBox>(box)) {
return compute_height_for_replaced_element(state, verify_cast<ReplacedBox>(box));
}
return compute_auto_height_for_block_level_element(state, box);
}
}