39b7fbfeb9
The previous implementation used relative X offsets for both left and right-side floats. This made right-side floats super awkward, since we could only determine their X position once the width of the BFC root was known, and for BFC roots with automatic width, this was not even working at all most of the time. This patch changes the way we deal with floats so that BFC keeps track of the offset-from-edge for each float. The offset is the distance from the BFC root edge (left or right, depending on float direction) to the "innermost" margin edge of the floating box. Floating box are now laid out in two passes: while going through the normal flow layout, we put floats in their *static* position (i.e the position they would have occupied if they weren't floating) and then update the Y position value to the final one. The second pass occurs later on, when the BFC root has had its width assigned by the parent context. Once we know the root width, we can set the X position value of floating boxes. (Because the X position of right-side floats is relative to the right edge of the BFC root.)
116 lines
3.7 KiB
C++
116 lines
3.7 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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// 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(FormattingState&, BlockContainer const&, FormattingContext* parent);
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~BlockFormattingContext();
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virtual void run(Box const&, LayoutMode) 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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static float compute_theoretical_height(FormattingState const&, Box const&);
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void compute_width(Box const&, LayoutMode = LayoutMode::Default);
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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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static void compute_height(Box const&, FormattingState&);
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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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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&, LayoutMode);
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void compute_width_for_block_level_replaced_element_in_normal_flow(ReplacedBox const&);
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void layout_initial_containing_block(LayoutMode);
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void layout_block_level_children(BlockContainer const&, LayoutMode);
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void layout_inline_children(BlockContainer const&, LayoutMode);
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void compute_vertical_box_model_metrics(Box const& box, BlockContainer const& containing_block);
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void place_block_level_element_in_normal_flow_horizontally(Box const& child_box, BlockContainer const&);
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void place_block_level_element_in_normal_flow_vertically(Box const& child_box, BlockContainer const&);
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void layout_floating_box(Box const& child, BlockContainer const& containing_block, LayoutMode);
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void apply_transformations_to_children(Box 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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