f25203f245
This is rather subtle and points to our architecture around definite sizes not being exactly right, but... At some points during flexbox layout, the spec tells us that the sizes of certain flex items are considered definite from this point on. We implement this by marking each item's associated UsedValues as "has-definite-width/height". However, this breaks code that tries to resolve computed "auto" sizes by taking the corresponding size from the containing block. The end result was that the 1st sizing pass in flexbox would find the right size for an "auto" sized item, but the 2nd pass would override the correct size with the containing block's content size in that axis instead. To work around the issue, FFC now remembers when it "definitizes" an item, and future attempts to resolve an "auto" computed size for that value will bypass the computed-auto-is-resolved-against-containing-block step of the algorithm. It's not perfect, and we'll need to think more about how to really represent these intermediate states relating to box sizes being definite..
199 lines
8.5 KiB
C++
199 lines
8.5 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <LibWeb/Layout/Box.h>
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#include <LibWeb/Layout/FormattingContext.h>
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namespace Web::Layout {
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class FlexFormattingContext final : public FormattingContext {
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public:
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FlexFormattingContext(LayoutState&, Box const& flex_container, FormattingContext* parent);
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~FlexFormattingContext();
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virtual bool inhibits_floating() const override { return true; }
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virtual void run(Box const&, LayoutMode) override;
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Box const& flex_container() const { return context_box(); }
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private:
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SizeConstraint flex_container_main_constraint() const;
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SizeConstraint flex_container_cross_constraint() const;
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void dump_items() const;
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struct DirectionAgnosticMargins {
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float main_before { 0 };
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float main_after { 0 };
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float cross_before { 0 };
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float cross_after { 0 };
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bool main_before_is_auto { false };
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bool main_after_is_auto { false };
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bool cross_before_is_auto { false };
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bool cross_after_is_auto { false };
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};
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struct FlexItem {
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Box& box;
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CSS::FlexBasisData used_flex_basis {};
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bool used_flex_basis_is_definite { false };
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float flex_base_size { 0 };
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float hypothetical_main_size { 0 };
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float hypothetical_cross_size { 0 };
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float hypothetical_cross_size_with_margins() { return hypothetical_cross_size + margins.cross_before + margins.cross_after + borders.cross_after + borders.cross_before + padding.cross_after + padding.cross_before; }
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float target_main_size { 0 };
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bool frozen { false };
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Optional<float> flex_factor {};
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float scaled_flex_shrink_factor { 0 };
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float desired_flex_fraction { 0 };
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float main_size { 0 };
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float cross_size { 0 };
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float main_offset { 0 };
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float cross_offset { 0 };
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DirectionAgnosticMargins margins {};
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DirectionAgnosticMargins borders {};
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DirectionAgnosticMargins padding {};
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bool is_min_violation { false };
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bool is_max_violation { false };
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bool has_assigned_definite_main_size { false };
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bool has_assigned_definite_cross_size { false };
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float add_main_margin_box_sizes(float content_size) const
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{
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return content_size + margins.main_before + margins.main_after + borders.main_before + borders.main_after + padding.main_before + padding.main_after;
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}
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float add_cross_margin_box_sizes(float content_size) const
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{
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return content_size + margins.cross_before + margins.cross_after + borders.cross_before + borders.cross_after + padding.cross_before + padding.cross_after;
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}
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};
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struct FlexLine {
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Vector<FlexItem*> items;
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float cross_size { 0 };
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float remaining_free_space { 0 };
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float chosen_flex_fraction { 0 };
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};
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bool has_definite_main_size(Box const&) const;
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bool has_definite_cross_size(Box const&) const;
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float specified_main_size(Box const&) const;
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float specified_cross_size(Box const&) const;
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float resolved_definite_main_size(FlexItem const&) const;
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float resolved_definite_cross_size(FlexItem const&) const;
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bool has_main_min_size(Box const&) const;
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bool has_cross_min_size(Box const&) const;
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float specified_main_max_size(Box const&) const;
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float specified_cross_max_size(Box const&) const;
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float calculated_main_size(Box const&) const;
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bool is_cross_auto(Box const&) const;
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float specified_main_size_of_child_box(Box const& child_box) const;
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float specified_main_min_size(Box const&) const;
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float specified_cross_min_size(Box const&) const;
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bool has_main_max_size(Box const&) const;
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bool has_cross_max_size(Box const&) const;
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float sum_of_margin_padding_border_in_main_axis(Box const&) const;
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float automatic_minimum_size(FlexItem const&) const;
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float content_based_minimum_size(FlexItem const&) const;
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Optional<float> specified_size_suggestion(FlexItem const&) const;
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Optional<float> transferred_size_suggestion(FlexItem const&) const;
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float content_size_suggestion(FlexItem const&) const;
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CSS::LengthPercentage const& computed_main_size(Box const&) const;
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CSS::LengthPercentage const& computed_main_min_size(Box const&) const;
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CSS::LengthPercentage const& computed_main_max_size(Box const&) const;
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CSS::LengthPercentage const& computed_cross_size(Box const&) const;
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CSS::LengthPercentage const& computed_cross_min_size(Box const&) const;
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CSS::LengthPercentage const& computed_cross_max_size(Box const&) const;
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float get_pixel_width(Box const& box, Optional<CSS::LengthPercentage> const& length_percentage) const;
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float get_pixel_height(Box const& box, Optional<CSS::LengthPercentage> const& length_percentage) const;
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bool flex_item_is_stretched(FlexItem const&) const;
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void set_main_size(Box const&, float size);
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void set_cross_size(Box const&, float size);
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void set_has_definite_main_size(Box const&, bool);
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void set_has_definite_cross_size(Box const&, bool);
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void set_offset(Box const&, float main_offset, float cross_offset);
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void set_main_axis_first_margin(FlexItem&, float margin);
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void set_main_axis_second_margin(FlexItem&, float margin);
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void copy_dimensions_from_flex_items_to_boxes();
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void generate_anonymous_flex_items();
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void determine_available_main_and_cross_space(bool& main_is_constrained, bool& cross_is_constrained, float& main_min_size, float& main_max_size, float& cross_min_size, float& cross_max_size);
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float calculate_indefinite_main_size(FlexItem const&);
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void determine_flex_base_size_and_hypothetical_main_size(FlexItem&);
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void determine_main_size_of_flex_container(bool main_is_constrained, float main_min_size, float main_max_size);
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void collect_flex_items_into_flex_lines();
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void resolve_flexible_lengths();
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void determine_hypothetical_cross_size_of_item(FlexItem&, bool resolve_percentage_min_max_sizes);
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void calculate_cross_size_of_each_flex_line(float cross_min_size, float cross_max_size);
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CSS::AlignItems alignment_for_item(FlexItem const&) const;
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void determine_used_cross_size_of_each_flex_item();
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void distribute_any_remaining_free_space();
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void align_all_flex_items_along_the_cross_axis();
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void determine_flex_container_used_cross_size(float cross_min_size, float cross_max_size);
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void align_all_flex_lines();
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bool is_row_layout() const { return m_flex_direction == CSS::FlexDirection::Row || m_flex_direction == CSS::FlexDirection::RowReverse; }
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bool is_single_line() const { return flex_container().computed_values().flex_wrap() == CSS::FlexWrap::Nowrap; }
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bool is_direction_reverse() const { return m_flex_direction == CSS::FlexDirection::ColumnReverse || m_flex_direction == CSS::FlexDirection::RowReverse; }
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void populate_specified_margins(FlexItem&, CSS::FlexDirection) const;
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void determine_intrinsic_size_of_flex_container(LayoutMode);
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[[nodiscard]] float calculate_intrinsic_main_size_of_flex_container(LayoutMode);
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[[nodiscard]] float calculate_intrinsic_cross_size_of_flex_container(LayoutMode);
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[[nodiscard]] float calculate_cross_min_content_contribution(FlexItem const&, bool resolve_percentage_min_max_sizes) const;
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[[nodiscard]] float calculate_cross_max_content_contribution(FlexItem const&, bool resolve_percentage_min_max_sizes) const;
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[[nodiscard]] float calculate_main_min_content_contribution(FlexItem const&) const;
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[[nodiscard]] float calculate_main_max_content_contribution(FlexItem const&) const;
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[[nodiscard]] float calculate_min_content_main_size(FlexItem const&) const;
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[[nodiscard]] float calculate_max_content_main_size(FlexItem const&) const;
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[[nodiscard]] float calculate_min_content_cross_size(FlexItem const&) const;
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[[nodiscard]] float calculate_max_content_cross_size(FlexItem const&) const;
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[[nodiscard]] float calculate_fit_content_main_size(FlexItem const&) const;
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[[nodiscard]] float calculate_fit_content_cross_size(FlexItem const&) const;
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virtual void parent_context_did_dimension_child_root_box() override;
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CSS::FlexBasisData used_flex_basis_for_item(FlexItem const&) const;
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LayoutState::UsedValues& m_flex_container_state;
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Vector<FlexLine> m_flex_lines;
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Vector<FlexItem> m_flex_items;
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CSS::FlexDirection m_flex_direction {};
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struct AvailableSpace {
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Optional<float> main;
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Optional<float> cross;
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};
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Optional<AvailableSpace> m_available_space;
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};
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}
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