147c3b3d97
Although DistinctNumeric, which is supposed to abstract the underlying type, was used to represent CSSPixels, we have a whole bunch of places in the layout code that assume CSSPixels::value() returns a floating-point type. This assumption makes it difficult to replace the underlying type in CSSPixels with a non-floating type. To make it easier to transition CSSPixels to fixed-point math, one step we can take is to prevent access to the underlying type using value() and instead use explicit conversions with the to_float(), to_double(), and to_int() methods.
406 lines
17 KiB
C++
406 lines
17 KiB
C++
/*
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* Copyright (c) 2022-2023, 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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#include <AK/Debug.h>
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#include <LibWeb/Layout/AvailableSpace.h>
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#include <LibWeb/Layout/BlockContainer.h>
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#include <LibWeb/Layout/LayoutState.h>
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#include <LibWeb/Layout/TextNode.h>
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namespace Web::Layout {
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LayoutState::LayoutState(LayoutState const* parent)
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: m_parent(parent)
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, m_root(find_root())
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{
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}
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LayoutState::~LayoutState()
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{
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}
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LayoutState::UsedValues& LayoutState::get_mutable(NodeWithStyleAndBoxModelMetrics const& box)
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{
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if (auto* used_values = used_values_per_layout_node.get(&box).value_or(nullptr))
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return *used_values;
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for (auto const* ancestor = m_parent; ancestor; ancestor = ancestor->m_parent) {
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if (auto* ancestor_used_values = ancestor->used_values_per_layout_node.get(&box).value_or(nullptr)) {
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auto cow_used_values = adopt_own(*new UsedValues(*ancestor_used_values));
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auto* cow_used_values_ptr = cow_used_values.ptr();
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used_values_per_layout_node.set(&box, move(cow_used_values));
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return *cow_used_values_ptr;
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}
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}
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auto const* containing_block_used_values = box.is_viewport() ? nullptr : &get(*box.containing_block());
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auto new_used_values = adopt_own(*new UsedValues);
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auto* new_used_values_ptr = new_used_values.ptr();
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new_used_values->set_node(const_cast<NodeWithStyleAndBoxModelMetrics&>(box), containing_block_used_values);
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used_values_per_layout_node.set(&box, move(new_used_values));
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return *new_used_values_ptr;
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}
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LayoutState::UsedValues const& LayoutState::get(NodeWithStyleAndBoxModelMetrics const& box) const
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{
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if (auto const* used_values = used_values_per_layout_node.get(&box).value_or(nullptr))
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return *used_values;
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for (auto const* ancestor = m_parent; ancestor; ancestor = ancestor->m_parent) {
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if (auto const* ancestor_used_values = ancestor->used_values_per_layout_node.get(&box).value_or(nullptr))
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return *ancestor_used_values;
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}
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auto const* containing_block_used_values = box.is_viewport() ? nullptr : &get(*box.containing_block());
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auto new_used_values = adopt_own(*new UsedValues);
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auto* new_used_values_ptr = new_used_values.ptr();
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new_used_values->set_node(const_cast<NodeWithStyleAndBoxModelMetrics&>(box), containing_block_used_values);
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const_cast<LayoutState*>(this)->used_values_per_layout_node.set(&box, move(new_used_values));
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return *new_used_values_ptr;
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}
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static void measure_scrollable_overflow(LayoutState const& state, Box const& box, CSSPixels& bottom_edge, CSSPixels& right_edge)
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{
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auto const* maybe_box_state = state.used_values_per_layout_node.get(&box).value_or(nullptr);
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if (!maybe_box_state)
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return;
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auto const& box_state = *maybe_box_state;
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auto scroll_container_border_box = CSSPixelRect {
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box_state.offset.translated(-box_state.border_box_left(), -box_state.border_box_top()),
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{ box_state.border_box_width(), box_state.border_box_height() }
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};
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bottom_edge = max(bottom_edge, scroll_container_border_box.bottom());
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right_edge = max(right_edge, scroll_container_border_box.right());
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if (box.children_are_inline()) {
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if (!box_state.line_boxes.is_empty()) {
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bottom_edge = max(bottom_edge, scroll_container_border_box.y() + box_state.line_boxes.last().bottom());
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for (auto& line_box : box_state.line_boxes) {
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if (line_box.fragments().is_empty())
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continue;
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right_edge = max(right_edge, scroll_container_border_box.x() + line_box.fragments().last().width());
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}
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}
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} else {
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// FIXME: Only check boxes for whom `box` is the containing block.
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box.for_each_child_of_type<Box>([&](Box const& child) {
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measure_scrollable_overflow(state, child, bottom_edge, right_edge);
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return IterationDecision::Continue;
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});
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}
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}
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void LayoutState::commit()
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{
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// Only the top-level LayoutState should ever be committed.
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VERIFY(!m_parent);
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HashTable<Layout::TextNode*> text_nodes;
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for (auto& it : used_values_per_layout_node) {
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auto& used_values = *it.value;
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auto& node = const_cast<NodeWithStyleAndBoxModelMetrics&>(used_values.node());
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// Transfer box model metrics.
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node.box_model().inset = { used_values.inset_top, used_values.inset_right, used_values.inset_bottom, used_values.inset_left };
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node.box_model().padding = { used_values.padding_top, used_values.padding_right, used_values.padding_bottom, used_values.padding_left };
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node.box_model().border = { used_values.border_top, used_values.border_right, used_values.border_bottom, used_values.border_left };
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node.box_model().margin = { used_values.margin_top, used_values.margin_right, used_values.margin_bottom, used_values.margin_left };
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node.set_paintable(node.create_paintable());
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// For boxes, transfer all the state needed for painting.
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if (is<Layout::Box>(node)) {
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auto& box = static_cast<Layout::Box const&>(node);
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auto& paintable_box = const_cast<Painting::PaintableBox&>(*box.paintable_box());
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paintable_box.set_offset(used_values.offset);
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paintable_box.set_content_size(used_values.content_width(), used_values.content_height());
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paintable_box.set_containing_line_box_fragment(used_values.containing_line_box_fragment);
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if (used_values.override_borders_data().has_value()) {
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paintable_box.set_override_borders_data(used_values.override_borders_data().value());
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}
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if (is<Layout::BlockContainer>(box)) {
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for (auto& line_box : used_values.line_boxes) {
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for (auto& fragment : line_box.fragments()) {
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if (fragment.layout_node().is_text_node())
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text_nodes.set(static_cast<Layout::TextNode*>(const_cast<Layout::Node*>(&fragment.layout_node())));
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}
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}
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static_cast<Painting::PaintableWithLines&>(paintable_box).set_line_boxes(move(used_values.line_boxes));
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}
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}
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}
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// Measure overflow in scroll containers.
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for (auto& it : used_values_per_layout_node) {
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auto& used_values = *it.value;
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if (!used_values.node().is_box())
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continue;
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auto const& box = static_cast<Layout::Box const&>(used_values.node());
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if (!box.is_scroll_container())
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continue;
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CSSPixels bottom_edge = 0;
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CSSPixels right_edge = 0;
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measure_scrollable_overflow(*this, box, bottom_edge, right_edge);
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auto padding_box = box.paintable_box()->absolute_padding_box_rect();
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if (bottom_edge > padding_box.height() || right_edge > padding_box.width()) {
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Painting::PaintableBox::OverflowData overflow_data;
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overflow_data.scrollable_overflow_rect = padding_box;
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overflow_data.scrollable_overflow_rect.set_size(right_edge, bottom_edge);
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const_cast<Painting::PaintableBox&>(*box.paintable_box()).set_overflow_data(overflow_data);
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}
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}
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for (auto* text_node : text_nodes)
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text_node->set_paintable(text_node->create_paintable());
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}
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void LayoutState::UsedValues::set_node(NodeWithStyleAndBoxModelMetrics& node, UsedValues const* containing_block_used_values)
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{
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m_node = &node;
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// NOTE: In the code below, we decide if `node` has definite width and/or height.
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// This attempts to cover all the *general* cases where CSS considers sizes to be definite.
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// If `node` has definite values for min/max-width or min/max-height and a definite
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// preferred size in the same axis, we clamp the preferred size here as well.
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//
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// There are additional cases where CSS considers values to be definite. We model all of
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// those by having our engine consider sizes to be definite *once they are assigned to
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// the UsedValues by calling set_content_width() or set_content_height().
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auto const& computed_values = node.computed_values();
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auto adjust_for_box_sizing = [&](CSSPixels unadjusted_pixels, CSS::Size const& computed_size, bool width) -> CSSPixels {
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// box-sizing: content-box and/or automatic size don't require any adjustment.
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if (computed_values.box_sizing() == CSS::BoxSizing::ContentBox || computed_size.is_auto())
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return unadjusted_pixels;
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// box-sizing: border-box requires us to subtract the relevant border and padding from the size.
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CSSPixels border_and_padding;
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if (width) {
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border_and_padding = CSSPixels(computed_values.border_left().width)
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+ computed_values.padding().left().to_px(*m_node, containing_block_used_values->content_width())
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+ CSSPixels(computed_values.border_right().width)
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+ computed_values.padding().right().to_px(*m_node, containing_block_used_values->content_width());
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} else {
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border_and_padding = CSSPixels(computed_values.border_top().width)
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+ computed_values.padding().top().to_px(*m_node, containing_block_used_values->content_width())
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+ CSSPixels(computed_values.border_bottom().width)
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+ computed_values.padding().bottom().to_px(*m_node, containing_block_used_values->content_width());
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}
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return unadjusted_pixels - border_and_padding;
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};
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auto is_definite_size = [&](CSS::Size const& size, CSSPixels& resolved_definite_size, bool width) {
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// A size that can be determined without performing layout; that is,
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// a <length>,
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// a measure of text (without consideration of line-wrapping),
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// a size of the initial containing block,
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// or a <percentage> or other formula (such as the “stretch-fit” sizing of non-replaced blocks [CSS2]) that is resolved solely against definite sizes.
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auto containing_block_has_definite_size = containing_block_used_values ? (width ? containing_block_used_values->has_definite_width() : containing_block_used_values->has_definite_height()) : false;
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if (size.is_auto()) {
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// NOTE: The width of a non-flex-item block is considered definite if it's auto and the containing block has definite width.
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if (width
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&& !node.is_floating()
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&& node.display().is_block_outside()
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&& node.parent()
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&& !node.parent()->is_floating()
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&& (node.parent()->display().is_flow_root_inside()
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|| node.parent()->display().is_flow_inside())) {
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if (containing_block_has_definite_size) {
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CSSPixels available_width = containing_block_used_values->content_width();
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resolved_definite_size = available_width
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- margin_left
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- margin_right
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- padding_left
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- padding_right
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- border_left
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- border_right;
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return true;
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}
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return false;
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}
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return false;
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}
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if (size.is_calculated()) {
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if (size.calculated().contains_percentage()) {
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if (!containing_block_has_definite_size)
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return false;
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auto containing_block_size_as_length = width
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? CSS::Length::make_px(containing_block_used_values->content_width())
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: CSS::Length::make_px(containing_block_used_values->content_height());
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resolved_definite_size = adjust_for_box_sizing(size.calculated().resolve_length_percentage(node, containing_block_size_as_length).value_or(CSS::Length::make_auto()).to_px(node), size, width);
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return true;
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}
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resolved_definite_size = adjust_for_box_sizing(size.calculated().resolve_length(node)->to_px(node), size, width);
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return true;
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}
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if (size.is_length()) {
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VERIFY(!size.is_auto()); // This should have been covered by the Size::is_auto() branch above.
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resolved_definite_size = adjust_for_box_sizing(size.length().to_px(node), size, width);
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return true;
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}
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if (size.is_percentage()) {
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if (containing_block_has_definite_size) {
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auto containing_block_size = width ? containing_block_used_values->content_width() : containing_block_used_values->content_height();
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resolved_definite_size = adjust_for_box_sizing(containing_block_size * static_cast<double>(size.percentage().as_fraction()), size, width);
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return true;
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}
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return false;
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}
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// FIXME: Determine if calc() value is definite.
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return false;
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};
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CSSPixels min_width = 0;
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bool has_definite_min_width = is_definite_size(computed_values.min_width(), min_width, true);
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CSSPixels max_width = 0;
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bool has_definite_max_width = is_definite_size(computed_values.max_width(), max_width, true);
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CSSPixels min_height = 0;
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bool has_definite_min_height = is_definite_size(computed_values.min_height(), min_height, false);
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CSSPixels max_height = 0;
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bool has_definite_max_height = is_definite_size(computed_values.max_height(), max_height, false);
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m_has_definite_width = is_definite_size(computed_values.width(), m_content_width, true);
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m_has_definite_height = is_definite_size(computed_values.height(), m_content_height, false);
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if (m_has_definite_width) {
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if (has_definite_min_width)
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m_content_width = max(min_width, m_content_width);
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if (has_definite_max_width)
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m_content_width = min(max_width, m_content_width);
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}
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if (m_has_definite_height) {
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if (has_definite_min_height)
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m_content_height = max(min_height, m_content_height);
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if (has_definite_max_height)
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m_content_height = min(max_height, m_content_height);
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}
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}
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void LayoutState::UsedValues::set_content_width(CSSPixels width)
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{
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VERIFY(isfinite(width.to_double()));
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if (width < 0) {
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// Negative widths are not allowed in CSS. We have a bug somewhere! Clamp to 0 to avoid doing too much damage.
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dbgln_if(LIBWEB_CSS_DEBUG, "FIXME: Layout calculated a negative width for {}: {}", m_node->debug_description(), width);
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width = 0;
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}
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m_content_width = width;
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m_has_definite_width = true;
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}
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void LayoutState::UsedValues::set_content_height(CSSPixels height)
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{
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VERIFY(isfinite(height.to_double()));
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if (height < 0) {
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// Negative heights are not allowed in CSS. We have a bug somewhere! Clamp to 0 to avoid doing too much damage.
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dbgln_if(LIBWEB_CSS_DEBUG, "FIXME: Layout calculated a negative height for {}: {}", m_node->debug_description(), height);
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height = 0;
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}
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m_content_height = height;
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m_has_definite_height = true;
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}
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void LayoutState::UsedValues::set_temporary_content_width(CSSPixels width)
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{
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m_content_width = width;
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}
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void LayoutState::UsedValues::set_temporary_content_height(CSSPixels height)
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{
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m_content_height = height;
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}
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AvailableSize LayoutState::UsedValues::available_width_inside() const
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{
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if (width_constraint == SizeConstraint::MinContent)
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return AvailableSize::make_min_content();
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if (width_constraint == SizeConstraint::MaxContent)
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return AvailableSize::make_max_content();
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if (has_definite_width())
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return AvailableSize::make_definite(m_content_width);
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return AvailableSize::make_indefinite();
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}
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AvailableSize LayoutState::UsedValues::available_height_inside() const
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{
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if (height_constraint == SizeConstraint::MinContent)
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return AvailableSize::make_min_content();
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if (height_constraint == SizeConstraint::MaxContent)
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return AvailableSize::make_max_content();
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if (has_definite_height())
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return AvailableSize::make_definite(m_content_height);
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return AvailableSize::make_indefinite();
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}
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AvailableSpace LayoutState::UsedValues::available_inner_space_or_constraints_from(AvailableSpace const& outer_space) const
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{
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auto inner_width = available_width_inside();
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auto inner_height = available_height_inside();
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if (inner_width.is_indefinite() && outer_space.width.is_intrinsic_sizing_constraint())
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inner_width = outer_space.width;
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if (inner_height.is_indefinite() && outer_space.height.is_intrinsic_sizing_constraint())
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inner_height = outer_space.height;
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return AvailableSpace(inner_width, inner_height);
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}
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void LayoutState::UsedValues::set_content_offset(CSSPixelPoint new_offset)
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{
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set_content_x(new_offset.x());
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set_content_y(new_offset.y());
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}
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void LayoutState::UsedValues::set_content_x(CSSPixels x)
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{
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offset.set_x(x);
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}
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void LayoutState::UsedValues::set_content_y(CSSPixels y)
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{
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offset.set_y(y);
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}
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void LayoutState::UsedValues::set_indefinite_content_width()
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{
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m_has_definite_width = false;
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}
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void LayoutState::UsedValues::set_indefinite_content_height()
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{
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m_has_definite_height = false;
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}
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void LayoutState::UsedValues::set_min_content_width()
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{
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width_constraint = SizeConstraint::MinContent;
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m_content_width = 0;
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m_has_definite_height = false;
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}
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void LayoutState::UsedValues::set_max_content_width()
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{
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width_constraint = SizeConstraint::MaxContent;
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m_content_width = INFINITY;
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m_has_definite_height = false;
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}
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}
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