ladybird/Libraries/LibWeb/Layout/InlineLevelIterator.cpp

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/*
* Copyright (c) 2022, Andreas Kling <andreas@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/DOM/ShadowRoot.h>
#include <LibWeb/HTML/FormAssociatedElement.h>
#include <LibWeb/Layout/BreakNode.h>
#include <LibWeb/Layout/InlineFormattingContext.h>
#include <LibWeb/Layout/InlineLevelIterator.h>
#include <LibWeb/Layout/InlineNode.h>
#include <LibWeb/Layout/ListItemMarkerBox.h>
#include <LibWeb/Layout/ReplacedBox.h>
namespace Web::Layout {
InlineLevelIterator::InlineLevelIterator(Layout::InlineFormattingContext& inline_formatting_context, Layout::LayoutState& layout_state, Layout::BlockContainer const& containing_block, LayoutState::UsedValues const& containing_block_used_values, LayoutMode layout_mode)
: m_inline_formatting_context(inline_formatting_context)
, m_layout_state(layout_state)
, m_containing_block(containing_block)
, m_containing_block_used_values(containing_block_used_values)
, m_next_node(containing_block.first_child())
, m_layout_mode(layout_mode)
{
skip_to_next();
generate_all_items();
}
void InlineLevelIterator::generate_all_items()
{
for (;;) {
auto item = generate_next_item();
if (!item.has_value())
break;
// Track accumulated width for tab calculations.
// Reset on forced breaks since tabs measure from line start.
if (item->type == Item::Type::ForcedBreak) {
m_accumulated_width_for_tabs = 0;
} else {
m_accumulated_width_for_tabs += item->border_box_width();
}
m_items.append(item.release_value());
}
}
void InlineLevelIterator::enter_node_with_box_model_metrics(Layout::NodeWithStyleAndBoxModelMetrics const& node)
{
if (!m_extra_leading_metrics.has_value())
m_extra_leading_metrics = ExtraBoxMetrics {};
// FIXME: It's really weird that *this* is where we assign box model metrics for these layout nodes..
auto& used_values = m_layout_state.get_mutable(node);
auto const& computed_values = node.computed_values();
used_values.margin_top = computed_values.margin().top().to_px_or_zero(node, m_containing_block_used_values.content_width());
used_values.margin_bottom = computed_values.margin().bottom().to_px_or_zero(node, m_containing_block_used_values.content_width());
used_values.margin_left = computed_values.margin().left().to_px_or_zero(node, m_containing_block_used_values.content_width());
used_values.border_left = computed_values.border_left().width;
used_values.padding_left = computed_values.padding().left().to_px_or_zero(node, m_containing_block_used_values.content_width());
used_values.margin_right = computed_values.margin().right().to_px_or_zero(node, m_containing_block_used_values.content_width());
used_values.border_right = computed_values.border_right().width;
used_values.padding_right = computed_values.padding().right().to_px_or_zero(node, m_containing_block_used_values.content_width());
used_values.border_top = computed_values.border_top().width;
used_values.border_bottom = computed_values.border_bottom().width;
used_values.padding_bottom = computed_values.padding().bottom().to_px_or_zero(node, m_containing_block_used_values.content_width());
used_values.padding_top = computed_values.padding().top().to_px_or_zero(node, m_containing_block_used_values.content_width());
m_extra_leading_metrics->margin += used_values.margin_left;
m_extra_leading_metrics->border += used_values.border_left;
m_extra_leading_metrics->padding += used_values.padding_left;
// Now's our chance to resolve the inset properties for this node.
m_inline_formatting_context.compute_inset(node, m_inline_formatting_context.content_box_rect(m_containing_block_used_values).size());
m_box_model_node_stack.append(node);
}
void InlineLevelIterator::exit_node_with_box_model_metrics()
{
if (!m_extra_trailing_metrics.has_value())
m_extra_trailing_metrics = ExtraBoxMetrics {};
auto& node = m_box_model_node_stack.last();
auto& used_values = m_layout_state.get_mutable(node);
m_extra_trailing_metrics->margin += used_values.margin_right;
m_extra_trailing_metrics->border += used_values.border_right;
m_extra_trailing_metrics->padding += used_values.padding_right;
m_box_model_node_stack.take_last();
}
// This is similar to Layout::Node::next_in_pre_order() but will not descend into inline-block nodes.
Layout::Node const* InlineLevelIterator::next_inline_node_in_pre_order(Layout::Node const& current, Layout::Node const* stay_within)
{
if (current.first_child()
&& current.first_child()->display().is_inline_outside()
&& current.display().is_flow_inside()
&& !current.is_replaced_box()) {
if (!current.is_box() || !static_cast<Box const&>(current).is_out_of_flow(m_inline_formatting_context))
return current.first_child();
}
Layout::Node const* node = &current;
Layout::Node const* next = nullptr;
while (!(next = node->next_sibling())) {
node = node->parent();
// If node is the last node on the "box model node stack", pop it off.
if (!m_box_model_node_stack.is_empty()
&& m_box_model_node_stack.last() == node) {
exit_node_with_box_model_metrics();
}
if (!node || node == stay_within)
return nullptr;
}
// If node is the last node on the "box model node stack", pop it off.
if (!m_box_model_node_stack.is_empty()
&& m_box_model_node_stack.last() == node) {
exit_node_with_box_model_metrics();
}
return next;
}
void InlineLevelIterator::compute_next()
{
if (m_next_node == nullptr)
return;
do {
m_next_node = next_inline_node_in_pre_order(*m_next_node, m_containing_block);
if (m_next_node && m_next_node->is_svg_mask_box()) {
// NOTE: It is possible to encounter SVGMaskBox nodes while doing layout of formatting context established by <foreignObject> with a mask.
// We should skip and let SVGFormattingContext take care of them.
m_next_node = m_next_node->next_sibling();
}
} while (m_next_node && (!m_next_node->is_inline() && !m_next_node->is_out_of_flow(m_inline_formatting_context)));
}
void InlineLevelIterator::skip_to_next()
{
if (m_next_node
&& is<Layout::NodeWithStyleAndBoxModelMetrics>(*m_next_node)
&& m_next_node->display().is_flow_inside()
&& !m_next_node->is_out_of_flow(m_inline_formatting_context)
&& !m_next_node->is_replaced_box())
enter_node_with_box_model_metrics(static_cast<Layout::NodeWithStyleAndBoxModelMetrics const&>(*m_next_node));
m_current_node = m_next_node;
compute_next();
}
Optional<InlineLevelIterator::Item> InlineLevelIterator::next()
{
if (m_next_item_index >= m_items.size())
return {};
return m_items[m_next_item_index++];
}
CSSPixels InlineLevelIterator::next_non_whitespace_sequence_width()
{
CSSPixels next_width = 0;
for (size_t i = m_next_item_index; i < m_items.size(); ++i) {
auto const& next_item = m_items[i];
if (next_item.type == InlineLevelIterator::Item::Type::ForcedBreak)
break;
if (next_item.node->computed_values().text_wrap_mode() == CSS::TextWrapMode::Wrap) {
if (next_item.type != InlineLevelIterator::Item::Type::Text)
break;
if (next_item.is_collapsible_whitespace)
break;
auto const& next_text_node = as<Layout::TextNode>(*(next_item.node));
auto next_view = next_text_node.text_for_rendering().substring_view(next_item.offset_in_node, next_item.length_in_node);
if (next_view.is_ascii_whitespace())
break;
}
next_width += next_item.border_box_width();
}
return next_width;
}
Gfx::GlyphRun::TextType InlineLevelIterator::resolve_text_direction_from_context()
{
VERIFY(m_text_node_context.has_value());
// Search forward in the pre-generated chunks array to find the next chunk with known direction.
// Since chunks are pre-generated, this is just O(1) array access per iteration.
Optional<Gfx::GlyphRun::TextType> next_known_direction;
for (size_t i = m_text_node_context->next_chunk_index; i < m_text_node_context->chunks.size(); ++i) {
auto const& chunk = m_text_node_context->chunks[i];
if (chunk.text_type == Gfx::GlyphRun::TextType::Ltr || chunk.text_type == Gfx::GlyphRun::TextType::Rtl) {
next_known_direction = chunk.text_type;
break;
}
}
auto last_known_direction = m_text_node_context->last_known_direction;
if (last_known_direction.has_value() && next_known_direction.has_value() && *last_known_direction != *next_known_direction) {
switch (m_containing_block->computed_values().direction()) {
case CSS::Direction::Ltr:
return Gfx::GlyphRun::TextType::Ltr;
case CSS::Direction::Rtl:
return Gfx::GlyphRun::TextType::Rtl;
}
}
if (last_known_direction.has_value())
return *last_known_direction;
if (next_known_direction.has_value())
return *next_known_direction;
return Gfx::GlyphRun::TextType::ContextDependent;
}
Optional<InlineLevelIterator::Item> InlineLevelIterator::generate_next_item()
{
if (!m_current_node)
return {};
if (auto* text_node = as_if<Layout::TextNode>(*m_current_node)) {
if (!m_text_node_context.has_value())
enter_text_node(*text_node);
// Track chunk position locally
bool is_first_chunk = (m_text_node_context->next_chunk_index == 0);
// Get the next chunk from the pre-generated array
Optional<TextNode::Chunk> chunk_opt;
if (m_text_node_context->next_chunk_index < m_text_node_context->chunks.size()) {
chunk_opt = m_text_node_context->chunks[m_text_node_context->next_chunk_index++];
}
bool is_last_chunk = (m_text_node_context->next_chunk_index >= m_text_node_context->chunks.size());
auto is_empty_editable = false;
if (!chunk_opt.has_value()) {
auto const is_only_chunk = is_first_chunk && is_last_chunk;
if (is_only_chunk && text_node->text_for_rendering().is_empty()) {
if (auto const* shadow_root = as_if<DOM::ShadowRoot>(text_node->dom_node().root()))
if (auto const* form_associated_element = as_if<HTML::FormAssociatedTextControlElement>(shadow_root->host()))
is_empty_editable = form_associated_element->text_control_to_html_element().is_mutable();
is_empty_editable |= text_node->dom_node().parent() && text_node->dom_node().parent()->is_editing_host();
}
if (is_empty_editable) {
// Create an empty chunk for editable empty text fields
chunk_opt = TextNode::Chunk {
.view = {},
.font = text_node->computed_values().font_list().first(),
.is_all_whitespace = true,
.text_type = Gfx::GlyphRun::TextType::Common,
};
// Advance the index so the next call will move to the next node
m_text_node_context->next_chunk_index = 1;
} else {
m_text_node_context = {};
m_previous_chunk_can_break_after = false;
skip_to_next();
return generate_next_item();
}
}
auto& chunk = chunk_opt.value();
auto text_type = chunk.text_type;
if (text_type == Gfx::GlyphRun::TextType::Ltr || text_type == Gfx::GlyphRun::TextType::Rtl) {
m_text_node_context->last_known_direction = text_type;
}
auto do_respect_linebreak = m_text_node_context->should_respect_linebreaks;
if (do_respect_linebreak && chunk.has_breaking_newline) {
is_last_chunk = true;
if (chunk.is_all_whitespace)
text_type = Gfx::GlyphRun::TextType::EndPadding;
}
if (text_type == Gfx::GlyphRun::TextType::ContextDependent)
text_type = resolve_text_direction_from_context();
if (do_respect_linebreak && chunk.has_breaking_newline)
return Item { .type = Item::Type::ForcedBreak };
auto letter_spacing = text_node->computed_values().letter_spacing();
// FIXME: We should apply word spacing to all word-separator characters not just breaking tabs
auto word_spacing = text_node->computed_values().word_spacing();
auto x = 0.0f;
if (chunk.has_breaking_tab) {
// Use the accumulated width we've been tracking during pre-generation.
// This accounts for items that would appear before this tab on the same line.
CSSPixels accumulated_width = m_accumulated_width_for_tabs;
// https://drafts.csswg.org/css-text/#tab-size-property
auto tab_width = text_node->computed_values().tab_size().visit(
[&](CSS::Length const& length) -> CSSPixels {
return length.absolute_length_to_px();
},
[&](double tab_number) -> CSSPixels {
return CSSPixels::nearest_value_for(tab_number * (chunk.font->glyph_width(' ') + word_spacing.to_float() + letter_spacing.to_float()));
});
// https://drafts.csswg.org/css-text/#white-space-phase-2
// if fragments have added to the width, calculate the net distance to the next tab stop, otherwise the shift will just be the tab width
auto tab_stop_dist = accumulated_width > 0 ? (ceil((accumulated_width / tab_width)) * tab_width) - accumulated_width : tab_width;
auto ch_width = chunk.font->glyph_width('0');
// If this distance is less than 0.5ch, then the subsequent tab stop is used instead
if (tab_stop_dist < ch_width * 0.5)
tab_stop_dist += tab_width;
// account for consecutive tabs
auto num_of_tabs = 0;
for (auto code_point : chunk.view) {
if (code_point != '\t')
break;
num_of_tabs++;
}
tab_stop_dist = tab_stop_dist * num_of_tabs;
// remove tabs, we don't want to render them when we shape the text
chunk.view = chunk.view.substring_view(num_of_tabs);
x = tab_stop_dist.to_float();
}
auto glyph_run = Gfx::shape_text({ x, 0 }, letter_spacing.to_float(), chunk.view, chunk.font, text_type);
CSSPixels chunk_width = CSSPixels::nearest_value_for(glyph_run->width() + x);
// NOTE: We never consider `content: ""` to be collapsible whitespace.
bool is_generated_empty_string = is_empty_editable || (text_node->is_generated_for_pseudo_element() && chunk.length == 0);
auto collapse_whitespace = m_text_node_context->should_collapse_whitespace;
Item item {
.type = Item::Type::Text,
.node = text_node,
.glyph_run = move(glyph_run),
.offset_in_node = chunk.start,
.length_in_node = chunk.length,
.width = chunk_width,
.is_collapsible_whitespace = collapse_whitespace && chunk.is_all_whitespace && !is_generated_empty_string,
.can_break_before = m_previous_chunk_can_break_after,
};
m_previous_chunk_can_break_after = chunk.can_break_after;
add_extra_box_model_metrics_to_item(item, is_first_chunk, is_last_chunk);
return item;
}
if (m_current_node->is_absolutely_positioned()) {
auto const& node = *m_current_node;
skip_to_next();
return Item {
.type = Item::Type::AbsolutelyPositionedElement,
.node = &node,
};
}
if (m_current_node->is_floating()) {
auto const& node = *m_current_node;
skip_to_next();
return Item {
.type = Item::Type::FloatingElement,
.node = &node,
};
}
if (is<Layout::BreakNode>(*m_current_node)) {
auto const& node = *m_current_node;
skip_to_next();
return Item {
.type = Item::Type::ForcedBreak,
.node = &node,
};
}
if (is<Layout::ListItemMarkerBox>(*m_current_node)) {
skip_to_next();
return generate_next_item();
}
if (!is<Layout::Box>(*m_current_node)) {
skip_to_next();
return generate_next_item();
}
auto const& box = as<Layout::Box>(*m_current_node);
auto const& box_state = m_layout_state.get(box);
m_inline_formatting_context.dimension_box_on_line(box, m_layout_mode);
auto item = Item {
.type = Item::Type::Element,
.node = &box,
.offset_in_node = 0,
.length_in_node = 0,
.width = box_state.content_width(),
.padding_start = box_state.padding_left,
.padding_end = box_state.padding_right,
.border_start = box_state.border_left,
.border_end = box_state.border_right,
.margin_start = box_state.margin_left,
.margin_end = box_state.margin_right,
};
add_extra_box_model_metrics_to_item(item, true, true);
skip_to_next();
return item;
}
void InlineLevelIterator::enter_text_node(Layout::TextNode const& text_node)
{
auto white_space_collapse = text_node.computed_values().white_space_collapse();
auto text_wrap_mode = text_node.computed_values().text_wrap_mode();
// https://drafts.csswg.org/css-text-4/#collapse
bool do_wrap_lines = text_wrap_mode == CSS::TextWrapMode::Wrap;
bool do_respect_linebreaks = first_is_one_of(white_space_collapse, CSS::WhiteSpaceCollapse::Preserve, CSS::WhiteSpaceCollapse::PreserveBreaks, CSS::WhiteSpaceCollapse::BreakSpaces);
// Pre-generate all chunks for this text node upfront.
// This allows O(1) peek() and next() operations instead of lazy generation with O(n) queue operations.
TextNode::ChunkIterator chunk_iterator { text_node, do_wrap_lines, do_respect_linebreaks };
Vector<TextNode::Chunk> chunks;
while (true) {
auto chunk = chunk_iterator.next();
if (!chunk.has_value())
break;
chunks.append(chunk.release_value());
}
m_text_node_context = TextNodeContext {
.chunks = move(chunks),
.next_chunk_index = 0,
.should_collapse_whitespace = chunk_iterator.should_collapse_whitespace(),
.should_wrap_lines = do_wrap_lines,
.should_respect_linebreaks = do_respect_linebreaks,
};
}
void InlineLevelIterator::add_extra_box_model_metrics_to_item(Item& item, bool add_leading_metrics, bool add_trailing_metrics)
{
if (add_leading_metrics && m_extra_leading_metrics.has_value()) {
item.margin_start += m_extra_leading_metrics->margin;
item.border_start += m_extra_leading_metrics->border;
item.padding_start += m_extra_leading_metrics->padding;
m_extra_leading_metrics = {};
}
if (add_trailing_metrics && m_extra_trailing_metrics.has_value()) {
item.margin_end += m_extra_trailing_metrics->margin;
item.border_end += m_extra_trailing_metrics->border;
item.padding_end += m_extra_trailing_metrics->padding;
m_extra_trailing_metrics = {};
}
}
}