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ladybird/Userland/Libraries/LibWeb/Layout/FormattingContext.h
Aliaksandr Kalenik 863416e3ac LibWeb: Make FC of containing block responsible for abspos layout 
Before this change, a formatting context was responsible for layout of
absolutely positioned boxes whose FC root box was their parent (either
directly or indirectly). This only worked correctly when the containing
block of the absolutely positioned child did not escape the FC root.
This is because the width and height of an absolutely positioned box are
resolved based on the size of its containing block, so we needed to
ensure that the containing block's layout was completed before laying
out an absolutely positioned box.

With this change, the layout of absolutely positioned boxes is delayed
until the FC responsible for the containing block's layout is complete.
This has affected the way we calculate the static position. It is no
longer possible to ask the FC for a box's static position, as this FC's
state might be gone by the time the layout for absolutely positioned
elements occurs. Instead, the "static position rectangle" (a concept
from the spec) is saved in the layout state, along with information on
how to align the box within this rectangle when its width and height are
resolved.
2024-09-12 07:36:32 +02:00

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/*
* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/OwnPtr.h>
#include <LibWeb/Forward.h>
#include <LibWeb/Layout/AvailableSpace.h>
#include <LibWeb/Layout/LayoutState.h>
namespace Web::Layout {
// NOTE: We use a custom clamping function here instead of AK::clamp(), since the AK version
// will VERIFY(max >= min) and CSS explicitly allows that (see css-values-4.)
template<typename T>
[[nodiscard]] constexpr T css_clamp(T const& value, T const& min, T const& max)
{
return ::max(min, ::min(value, max));
}
class FormattingContext {
public:
virtual ~FormattingContext();
enum class Type {
Block,
Inline,
Flex,
Grid,
Table,
SVG,
InternalReplaced, // Internal hack formatting context for replaced elements. FIXME: Get rid of this.
InternalDummy, // Internal hack formatting context for unimplemented things. FIXME: Get rid of this.
};
virtual void run(AvailableSpace const&) = 0;
// This function returns the automatic content height of the context's root box.
virtual CSSPixels automatic_content_width() const = 0;
// This function returns the automatic content height of the context's root box.
virtual CSSPixels automatic_content_height() const = 0;
Box const& context_box() const { return m_context_box; }
FormattingContext* parent() { return m_parent; }
FormattingContext const* parent() const { return m_parent; }
Type type() const { return m_type; }
bool is_block_formatting_context() const { return type() == Type::Block; }
virtual bool inhibits_floating() const { return false; }
[[nodiscard]] static Optional<Type> formatting_context_type_created_by_box(Box const&);
static bool creates_block_formatting_context(Box const&);
CSSPixels compute_table_box_width_inside_table_wrapper(Box const&, AvailableSpace const&);
CSSPixels compute_table_box_height_inside_table_wrapper(Box const&, AvailableSpace const&);
CSSPixels compute_width_for_replaced_element(Box const&, AvailableSpace const&) const;
CSSPixels compute_height_for_replaced_element(Box const&, AvailableSpace const&) const;
OwnPtr<FormattingContext> create_independent_formatting_context_if_needed(LayoutState&, LayoutMode, Box const& child_box);
virtual void parent_context_did_dimension_child_root_box() { }
CSSPixels calculate_min_content_width(Layout::Box const&) const;
CSSPixels calculate_max_content_width(Layout::Box const&) const;
CSSPixels calculate_min_content_height(Layout::Box const&, CSSPixels width) const;
CSSPixels calculate_max_content_height(Layout::Box const&, CSSPixels width) const;
CSSPixels calculate_fit_content_height(Layout::Box const&, AvailableSpace const&) const;
CSSPixels calculate_fit_content_width(Layout::Box const&, AvailableSpace const&) const;
CSSPixels calculate_inner_width(Layout::Box const&, AvailableSize const&, CSS::Size const& width) const;
CSSPixels calculate_inner_height(Layout::Box const&, AvailableSize const&, CSS::Size const& height) const;
virtual CSSPixels greatest_child_width(Box const&) const;
[[nodiscard]] CSSPixelRect absolute_content_rect(Box const&) const;
[[nodiscard]] CSSPixelRect absolute_content_rect(LayoutState::UsedValues const&) const;
[[nodiscard]] CSSPixelRect margin_box_rect(Box const&) const;
[[nodiscard]] CSSPixelRect margin_box_rect_in_ancestor_coordinate_space(Box const&, Box const& ancestor_box) const;
[[nodiscard]] CSSPixelRect margin_box_rect(LayoutState::UsedValues const&) const;
[[nodiscard]] CSSPixelRect margin_box_rect_in_ancestor_coordinate_space(LayoutState::UsedValues const&, Box const& ancestor_box) const;
[[nodiscard]] CSSPixelRect border_box_rect(Box const&) const;
[[nodiscard]] CSSPixelRect border_box_rect(LayoutState::UsedValues const&) const;
[[nodiscard]] CSSPixelRect border_box_rect_in_ancestor_coordinate_space(Box const&, Box const& ancestor_box) const;
[[nodiscard]] CSSPixelRect border_box_rect_in_ancestor_coordinate_space(LayoutState::UsedValues const&, Box const& ancestor_box) const;
[[nodiscard]] CSSPixelRect content_box_rect(Box const&) const;
[[nodiscard]] CSSPixelRect content_box_rect(LayoutState::UsedValues const&) const;
[[nodiscard]] CSSPixelRect content_box_rect_in_ancestor_coordinate_space(Box const&, Box const& ancestor_box) const;
[[nodiscard]] CSSPixelRect content_box_rect_in_ancestor_coordinate_space(LayoutState::UsedValues const&, Box const& ancestor_box) const;
[[nodiscard]] CSSPixels box_baseline(Box const&) const;
[[nodiscard]] CSSPixelRect content_box_rect_in_static_position_ancestor_coordinate_space(Box const&, Box const& ancestor_box) const;
[[nodiscard]] CSSPixels containing_block_width_for(NodeWithStyleAndBoxModelMetrics const&) const;
[[nodiscard]] CSSPixels containing_block_height_for(NodeWithStyleAndBoxModelMetrics const&) const;
[[nodiscard]] AvailableSize containing_block_width_as_available_size(NodeWithStyleAndBoxModelMetrics const&) const;
[[nodiscard]] AvailableSize containing_block_height_as_available_size(NodeWithStyleAndBoxModelMetrics const&) const;
[[nodiscard]] CSSPixels calculate_stretch_fit_width(Box const&, AvailableSize const&) const;
[[nodiscard]] CSSPixels calculate_stretch_fit_height(Box const&, AvailableSize const&) const;
virtual StaticPositionRect calculate_static_position_rect(Box const&) const;
bool can_skip_is_anonymous_text_run(Box&);
void compute_inset(NodeWithStyleAndBoxModelMetrics const&);
protected:
FormattingContext(Type, LayoutMode, LayoutState&, Box const&, FormattingContext* parent = nullptr);
static bool should_treat_width_as_auto(Box const&, AvailableSpace const&);
static bool should_treat_height_as_auto(Box const&, AvailableSpace const&);
[[nodiscard]] bool should_treat_max_width_as_none(Box const&, AvailableSize const&) const;
[[nodiscard]] bool should_treat_max_height_as_none(Box const&, AvailableSize const&) const;
OwnPtr<FormattingContext> layout_inside(Box const&, LayoutMode, AvailableSpace const&);
struct SpaceUsedByFloats {
CSSPixels left { 0 };
CSSPixels right { 0 };
};
struct SpaceUsedAndContainingMarginForFloats {
// Width for left / right floats, including their own margins.
CSSPixels left_used_space;
CSSPixels right_used_space;
// Left / right total margins from the outermost containing block to the floating element.
// Each block in the containing chain adds its own margin and we store the total here.
CSSPixels left_total_containing_margin;
CSSPixels right_total_containing_margin;
JS::GCPtr<Box const> matching_left_float_box;
};
struct ShrinkToFitResult {
CSSPixels preferred_width { 0 };
CSSPixels preferred_minimum_width { 0 };
};
CSSPixels tentative_width_for_replaced_element(Box const&, CSS::Size const& computed_width, AvailableSpace const&) const;
CSSPixels tentative_height_for_replaced_element(Box const&, CSS::Size const& computed_height, AvailableSpace const&) const;
CSSPixels compute_auto_height_for_block_formatting_context_root(Box const&) const;
[[nodiscard]] CSSPixelSize solve_replaced_size_constraint(CSSPixels input_width, CSSPixels input_height, Box const&, AvailableSpace const&) const;
ShrinkToFitResult calculate_shrink_to_fit_widths(Box const&);
void layout_absolutely_positioned_element(Box const&, AvailableSpace const&);
void compute_width_for_absolutely_positioned_element(Box const&, AvailableSpace const&);
void compute_width_for_absolutely_positioned_non_replaced_element(Box const&, AvailableSpace const&);
void compute_width_for_absolutely_positioned_replaced_element(Box const&, AvailableSpace const&);
enum class BeforeOrAfterInsideLayout {
Before,
After,
};
void compute_height_for_absolutely_positioned_element(Box const&, AvailableSpace const&, BeforeOrAfterInsideLayout);
void compute_height_for_absolutely_positioned_non_replaced_element(Box const&, AvailableSpace const&, BeforeOrAfterInsideLayout);
void compute_height_for_absolutely_positioned_replaced_element(Box const&, AvailableSpace const&, BeforeOrAfterInsideLayout);
[[nodiscard]] Optional<CSSPixels> compute_auto_height_for_absolutely_positioned_element(Box const&, AvailableSpace const&, BeforeOrAfterInsideLayout) const;
[[nodiscard]] Box const* box_child_to_derive_baseline_from(Box const&) const;
Type m_type {};
LayoutMode m_layout_mode;
FormattingContext* m_parent { nullptr };
JS::NonnullGCPtr<Box const> m_context_box;
LayoutState& m_state;
};
bool box_is_sized_as_replaced_element(Box const&);
}
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