ladybird/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
Andreas Kling 869b322a8f LibWeb: Assign hypothetical flex item main sizes as temporary main size
This colors a bit outside the lines of the specification, but the spec
doesn't offer a proper explanation for how descendants of a flex item
are supposed to have access to the flex item's main size for purposes
of percentage resolution.

The approach I came up with here was to take the hypothetical main size
of each flex item, and assign it as a temporary main size. This allows
percentage resolution in descendants to work against the pre-flexing
main size of items. This seems to match how other engines behave,
although it feels somewhat dirty. If/when we learn more about this,
we can come up with something nicer.
2022-10-15 14:01:54 +02:00

375 lines
16 KiB
C++

/*
* Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Layout/AvailableSpace.h>
#include <LibWeb/Layout/BlockContainer.h>
#include <LibWeb/Layout/LayoutState.h>
#include <LibWeb/Layout/TextNode.h>
namespace Web::Layout {
LayoutState::UsedValues& LayoutState::get_mutable(NodeWithStyleAndBoxModelMetrics const& box)
{
auto serial_id = box.serial_id();
if (used_values_per_layout_node[serial_id])
return *used_values_per_layout_node[serial_id];
for (auto const* ancestor = m_parent; ancestor; ancestor = ancestor->m_parent) {
if (ancestor->used_values_per_layout_node[serial_id]) {
auto cow_used_values = adopt_own(*new UsedValues(*ancestor->used_values_per_layout_node[serial_id]));
auto* cow_used_values_ptr = cow_used_values.ptr();
used_values_per_layout_node[serial_id] = move(cow_used_values);
return *cow_used_values_ptr;
}
}
auto const* containing_block_used_values = box.is_initial_containing_block_box() ? nullptr : &get(*box.containing_block());
used_values_per_layout_node[serial_id] = adopt_own(*new UsedValues);
used_values_per_layout_node[serial_id]->set_node(const_cast<NodeWithStyleAndBoxModelMetrics&>(box), containing_block_used_values);
return *used_values_per_layout_node[serial_id];
}
LayoutState::UsedValues const& LayoutState::get(NodeWithStyleAndBoxModelMetrics const& box) const
{
auto serial_id = box.serial_id();
if (used_values_per_layout_node[serial_id])
return *used_values_per_layout_node[serial_id];
for (auto* ancestor = m_parent; ancestor; ancestor = ancestor->m_parent) {
if (ancestor->used_values_per_layout_node[serial_id])
return *ancestor->used_values_per_layout_node[serial_id];
}
auto const* containing_block_used_values = box.is_initial_containing_block_box() ? nullptr : &get(*box.containing_block());
const_cast<LayoutState*>(this)->used_values_per_layout_node[serial_id] = adopt_own(*new UsedValues);
const_cast<LayoutState*>(this)->used_values_per_layout_node[serial_id]->set_node(const_cast<NodeWithStyleAndBoxModelMetrics&>(box), containing_block_used_values);
return *used_values_per_layout_node[serial_id];
}
void LayoutState::commit()
{
// Only the top-level LayoutState should ever be committed.
VERIFY(!m_parent);
HashTable<Layout::TextNode*> text_nodes;
for (auto& used_values_ptr : used_values_per_layout_node) {
if (!used_values_ptr)
continue;
auto& used_values = *used_values_ptr;
auto& node = const_cast<NodeWithStyleAndBoxModelMetrics&>(used_values.node());
// Transfer box model metrics.
node.box_model().inset = { used_values.inset_top, used_values.inset_right, used_values.inset_bottom, used_values.inset_left };
node.box_model().padding = { used_values.padding_top, used_values.padding_right, used_values.padding_bottom, used_values.padding_left };
node.box_model().border = { used_values.border_top, used_values.border_right, used_values.border_bottom, used_values.border_left };
node.box_model().margin = { used_values.margin_top, used_values.margin_right, used_values.margin_bottom, used_values.margin_left };
node.set_paintable(node.create_paintable());
// For boxes, transfer all the state needed for painting.
if (is<Layout::Box>(node)) {
auto& box = static_cast<Layout::Box const&>(node);
auto& paint_box = const_cast<Painting::PaintableBox&>(*box.paint_box());
paint_box.set_offset(used_values.offset);
paint_box.set_content_size(used_values.content_width(), used_values.content_height());
paint_box.set_overflow_data(move(used_values.overflow_data));
paint_box.set_containing_line_box_fragment(used_values.containing_line_box_fragment);
if (is<Layout::BlockContainer>(box)) {
for (auto& line_box : used_values.line_boxes) {
for (auto& fragment : line_box.fragments()) {
if (fragment.layout_node().is_text_node())
text_nodes.set(static_cast<Layout::TextNode*>(const_cast<Layout::Node*>(&fragment.layout_node())));
}
}
static_cast<Painting::PaintableWithLines&>(paint_box).set_line_boxes(move(used_values.line_boxes));
}
}
}
for (auto* text_node : text_nodes)
text_node->set_paintable(text_node->create_paintable());
}
Gfx::FloatRect margin_box_rect(Box const& box, LayoutState const& state)
{
auto const& box_state = state.get(box);
auto rect = Gfx::FloatRect { box_state.offset, { box_state.content_width(), box_state.content_height() } };
rect.set_x(rect.x() - box_state.margin_box_left());
rect.set_width(rect.width() + box_state.margin_box_left() + box_state.margin_box_right());
rect.set_y(rect.y() - box_state.margin_box_top());
rect.set_height(rect.height() + box_state.margin_box_top() + box_state.margin_box_bottom());
return rect;
}
Gfx::FloatRect border_box_rect(Box const& box, LayoutState const& state)
{
auto const& box_state = state.get(box);
auto rect = Gfx::FloatRect { box_state.offset, { box_state.content_width(), box_state.content_height() } };
rect.set_x(rect.x() - box_state.border_box_left());
rect.set_width(rect.width() + box_state.border_box_left() + box_state.border_box_right());
rect.set_y(rect.y() - box_state.border_box_top());
rect.set_height(rect.height() + box_state.border_box_top() + box_state.border_box_bottom());
return rect;
}
Gfx::FloatRect border_box_rect_in_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const& state)
{
auto rect = border_box_rect(box, state);
if (&box == &ancestor_box)
return rect;
for (auto const* current = box.containing_block(); current; current = current->containing_block()) {
if (current == &ancestor_box)
return rect;
auto const& current_state = state.get(static_cast<Box const&>(*current));
rect.translate_by(current_state.offset);
}
// If we get here, ancestor_box was not a containing block ancestor of `box`!
VERIFY_NOT_REACHED();
}
Gfx::FloatRect content_box_rect(Box const& box, LayoutState const& state)
{
auto const& box_state = state.get(box);
return Gfx::FloatRect { box_state.offset, { box_state.content_width(), box_state.content_height() } };
}
Gfx::FloatRect content_box_rect_in_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const& state)
{
auto rect = content_box_rect(box, state);
if (&box == &ancestor_box)
return rect;
for (auto const* current = box.containing_block(); current; current = current->containing_block()) {
if (current == &ancestor_box)
return rect;
auto const& current_state = state.get(static_cast<Box const&>(*current));
rect.translate_by(current_state.offset);
}
// If we get here, ancestor_box was not a containing block ancestor of `box`!
VERIFY_NOT_REACHED();
}
Gfx::FloatRect margin_box_rect_in_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const& state)
{
auto rect = margin_box_rect(box, state);
if (&box == &ancestor_box)
return rect;
for (auto const* current = box.containing_block(); current; current = current->containing_block()) {
if (current == &ancestor_box)
return rect;
auto const& current_state = state.get(static_cast<Box const&>(*current));
rect.translate_by(current_state.offset);
}
// If we get here, ancestor_box was not a containing block ancestor of `box`!
VERIFY_NOT_REACHED();
}
Gfx::FloatRect absolute_content_rect(Box const& box, LayoutState const& state)
{
auto const& box_state = state.get(box);
Gfx::FloatRect rect { box_state.offset, { box_state.content_width(), box_state.content_height() } };
for (auto* block = box.containing_block(); block; block = block->containing_block())
rect.translate_by(state.get(*block).offset);
return rect;
}
void LayoutState::UsedValues::set_node(NodeWithStyleAndBoxModelMetrics& node, UsedValues const* containing_block_used_values)
{
m_node = &node;
// NOTE: In the code below, we decide if `node` has definite width and/or height.
// This attempts to cover all the *general* cases where CSS considers sizes to be definite.
// If `node` has definite values for min/max-width or min/max-height and a definite
// preferred size in the same axis, we clamp the preferred size here as well.
//
// There are additional cases where CSS considers values to be definite. We model all of
// those by having our engine consider sizes to be definite *once they are assigned to
// the UsedValues by calling set_content_width() or set_content_height().
auto const& computed_values = node.computed_values();
auto is_definite_size = [&](CSS::Size const& size, float& resolved_definite_size, bool width) {
// A size that can be determined without performing layout; that is,
// a <length>,
// a measure of text (without consideration of line-wrapping),
// a size of the initial containing block,
// or a <percentage> or other formula (such as the “stretch-fit” sizing of non-replaced blocks [CSS2]) that is resolved solely against definite sizes.
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;
if (size.is_auto()) {
// NOTE: The width of a non-flex-item block is considered definite if it's auto and the containing block has definite width.
if (width
&& !node.is_floating()
&& node.display().is_block_outside()
&& node.parent()
&& !node.parent()->is_floating()
&& (node.parent()->display().is_flow_root_inside()
|| node.parent()->display().is_flow_inside())) {
if (containing_block_has_definite_size) {
float available_width = containing_block_used_values->content_width();
resolved_definite_size = available_width
- margin_left
- margin_right
- padding_left
- padding_right
- border_left
- border_right;
return true;
}
return false;
}
return false;
}
if (size.is_length() && size.length().is_calculated()) {
if (size.length().calculated_style_value()->contains_percentage()) {
if (!containing_block_has_definite_size)
return false;
auto& calc_value = *size.length().calculated_style_value();
auto containing_block_size_as_length = width
? CSS::Length::make_px(containing_block_used_values->content_width())
: CSS::Length::make_px(containing_block_used_values->content_height());
resolved_definite_size = calc_value.resolve_length_percentage(node, containing_block_size_as_length).value_or(CSS::Length::make_auto()).to_px(node);
return true;
}
resolved_definite_size = size.length().to_px(node);
return true;
}
if (size.is_length()) {
VERIFY(!size.is_auto()); // This should have been covered by the Size::is_auto() branch above.
VERIFY(!size.length().is_calculated()); // Covered above.
resolved_definite_size = size.length().to_px(node);
return true;
}
if (size.is_percentage()) {
if (containing_block_has_definite_size) {
auto containing_block_size = width ? containing_block_used_values->content_width() : containing_block_used_values->content_height();
resolved_definite_size = containing_block_size * size.percentage().as_fraction();
return true;
}
return false;
}
// FIXME: Determine if calc() value is definite.
return false;
};
float min_width = 0;
bool has_definite_min_width = is_definite_size(computed_values.min_width(), min_width, true);
float max_width = 0;
bool has_definite_max_width = is_definite_size(computed_values.max_width(), max_width, true);
float min_height = 0;
bool has_definite_min_height = is_definite_size(computed_values.min_height(), min_height, false);
float max_height = 0;
bool has_definite_max_height = is_definite_size(computed_values.max_height(), max_height, false);
m_has_definite_width = is_definite_size(computed_values.width(), m_content_width, true);
m_has_definite_height = is_definite_size(computed_values.height(), m_content_height, false);
if (m_has_definite_width) {
if (has_definite_min_width)
m_content_width = max(min_width, m_content_width);
if (has_definite_max_width)
m_content_width = min(max_width, m_content_width);
}
if (m_has_definite_height) {
if (has_definite_min_height)
m_content_height = max(min_height, m_content_height);
if (has_definite_max_height)
m_content_height = min(max_height, m_content_height);
}
}
void LayoutState::UsedValues::set_content_width(float width)
{
m_content_width = width;
m_has_definite_width = true;
}
void LayoutState::UsedValues::set_content_height(float height)
{
m_content_height = height;
m_has_definite_height = true;
}
void LayoutState::UsedValues::set_temporary_content_width(float width)
{
m_content_width = width;
}
void LayoutState::UsedValues::set_temporary_content_height(float height)
{
m_content_height = height;
}
float LayoutState::resolved_definite_width(Box const& box) const
{
return get(box).content_width();
}
float LayoutState::resolved_definite_height(Box const& box) const
{
return get(box).content_height();
}
AvailableSize LayoutState::UsedValues::available_width_inside() const
{
if (width_constraint == SizeConstraint::MinContent)
return AvailableSize::make_min_content();
if (width_constraint == SizeConstraint::MaxContent)
return AvailableSize::make_max_content();
if (has_definite_width())
return AvailableSize::make_definite(m_content_width);
return AvailableSize::make_indefinite();
}
AvailableSize LayoutState::UsedValues::available_height_inside() const
{
if (height_constraint == SizeConstraint::MinContent)
return AvailableSize::make_min_content();
if (height_constraint == SizeConstraint::MaxContent)
return AvailableSize::make_max_content();
if (has_definite_height())
return AvailableSize::make_definite(m_content_height);
return AvailableSize::make_indefinite();
}
AvailableSpace LayoutState::UsedValues::available_inner_space_or_constraints_from(AvailableSpace const& outer_space) const
{
auto inner_width = available_width_inside();
auto inner_height = available_height_inside();
if (inner_width.is_indefinite() && outer_space.width.is_intrinsic_sizing_constraint())
inner_width = outer_space.width;
if (inner_height.is_indefinite() && outer_space.height.is_intrinsic_sizing_constraint())
inner_height = outer_space.height;
return AvailableSpace(inner_width, inner_height);
}
void LayoutState::UsedValues::set_content_offset(Gfx::FloatPoint offset)
{
set_content_x(offset.x());
set_content_y(offset.y());
}
void LayoutState::UsedValues::set_content_x(float x)
{
offset.set_x(x);
}
void LayoutState::UsedValues::set_content_y(float y)
{
offset.set_y(y);
}
}