9c44634ca5
This is a big and messy change, and here's the gist: - AvaliableSpace is now 2x AvailableSize (width and height) - Layout algorithms are redesigned around the idea of available space - When doing layout across nested formatting contexts, the parent context tells the child context how much space is available for the child's root box in both axes. - "Available space" replaces "containing block width" in most places. - The width and height in a box's UsedValues are considered to be definite after they're assigned to. Marking something as having definite size is no longer a separate step, This probably introduces various regressions, but the big win here is that our layout system now works with available space, just like the specs are written. Fixing issues will be much easier going forward, since you don't need to do nearly as much conversion from "spec logic" to "LibWeb logic" as you previously did.
125 lines
4.3 KiB
C++
125 lines
4.3 KiB
C++
/*
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* Copyright (c) 2020-2022, 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 <AK/Vector.h>
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#include <LibWeb/Forward.h>
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#include <LibWeb/Layout/BlockContainer.h>
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#include <LibWeb/Layout/FormattingContext.h>
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namespace Web::Layout {
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class LineBuilder;
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// https://www.w3.org/TR/css-display/#block-formatting-context
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class BlockFormattingContext : public FormattingContext {
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public:
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explicit BlockFormattingContext(LayoutState&, BlockContainer const&, FormattingContext* parent);
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~BlockFormattingContext();
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virtual void run(Box const&, LayoutMode, AvailableSpace const&) override;
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virtual float automatic_content_height() const override;
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bool is_initial() const;
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auto const& left_side_floats() const { return m_left_floats; }
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auto const& right_side_floats() const { return m_right_floats; }
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void compute_width(Box const&, AvailableSpace const&, LayoutMode = LayoutMode::Normal);
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// https://www.w3.org/TR/css-display/#block-formatting-context-root
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BlockContainer const& root() const { return static_cast<BlockContainer const&>(context_box()); }
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virtual void parent_context_did_dimension_child_root_box() override;
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void compute_height(Box const&, AvailableSpace const&);
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void add_absolutely_positioned_box(Box const& box) { m_absolutely_positioned_boxes.append(box); }
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SpaceUsedByFloats space_used_by_floats(float y) const;
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virtual float greatest_child_width(Box const&) override;
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void layout_floating_box(Box const& child, BlockContainer const& containing_block, LayoutMode, AvailableSpace const&, LineBuilder* = nullptr);
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void layout_block_level_box(Box const&, BlockContainer const&, LayoutMode, float& bottom_of_lowest_margin_box, AvailableSpace const&);
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static bool should_treat_width_as_auto(Box const&, AvailableSpace const&);
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static bool should_treat_height_as_auto(Box const&, AvailableSpace const&);
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virtual bool can_determine_size_of_child() const override { return true; }
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virtual void determine_width_of_child(Box const&, AvailableSpace const&) override;
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virtual void determine_height_of_child(Box const&, AvailableSpace const&) override;
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private:
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virtual bool is_block_formatting_context() const final { return true; }
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void compute_width_for_floating_box(Box const&, AvailableSpace const&);
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void compute_width_for_block_level_replaced_element_in_normal_flow(ReplacedBox const&, AvailableSpace const&);
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void layout_initial_containing_block(LayoutMode, AvailableSpace const&);
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void layout_block_level_children(BlockContainer const&, LayoutMode, AvailableSpace const&);
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void layout_inline_children(BlockContainer const&, LayoutMode, AvailableSpace const&);
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static void resolve_vertical_box_model_metrics(Box const& box, AvailableSpace const&, LayoutState&);
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void place_block_level_element_in_normal_flow_horizontally(Box const& child_box, AvailableSpace const&);
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void place_block_level_element_in_normal_flow_vertically(Box const& child_box, AvailableSpace const&);
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void layout_list_item_marker(ListItemBox const&);
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enum class FloatSide {
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Left,
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Right,
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};
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struct FloatingBox {
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Box const& box;
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// Offset from left/right edge to the left content edge of `box`.
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float offset_from_edge { 0 };
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// Top margin edge of `box`.
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float top_margin_edge { 0 };
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// Bottom margin edge of `box`.
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float bottom_margin_edge { 0 };
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};
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struct FloatSideData {
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// Floating boxes currently accumulating on this side.
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Vector<FloatingBox&> current_boxes;
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// Combined width of boxes currently accumulating on this side.
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// This is the innermost margin of the innermost floating box.
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float current_width { 0 };
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// Highest value of `m_current_width` we've seen.
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float max_width { 0 };
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// All floating boxes encountered thus far within this BFC.
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Vector<NonnullOwnPtr<FloatingBox>> all_boxes;
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// Current Y offset from BFC root top.
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float y_offset { 0 };
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void clear()
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{
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current_boxes.clear();
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current_width = 0;
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}
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};
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FloatSideData m_left_floats;
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FloatSideData m_right_floats;
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Vector<Box const&> m_absolutely_positioned_boxes;
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bool m_was_notified_after_parent_dimensioned_my_root_box { false };
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};
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}
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