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/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, Tobias Christiansen <tobyase@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/CharacterTypes.h>
#include <AK/StringBuilder.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/Layout/BlockContainer.h>
#include <LibWeb/Layout/InlineFormattingContext.h>
#include <LibWeb/Layout/TextNode.h>
#include <LibWeb/Painting/TextPaintable.h>
namespace Web::Layout {
TextNode::TextNode(DOM::Document& document, DOM::Text& text)
: Node(document, &text)
{
set_inline(true);
}
TextNode::~TextNode()
{
}
static bool is_all_whitespace(StringView string)
{
for (size_t i = 0; i < string.length(); ++i) {
if (!is_ascii_space(string[i]))
return false;
}
return true;
}
// NOTE: This collapes whitespace into a single ASCII space if collapse is true. If previous_is_empty_or_ends_in_whitespace, it also strips leading whitespace.
void TextNode::compute_text_for_rendering(bool collapse, bool previous_is_empty_or_ends_in_whitespace)
{
auto& data = dom_node().data();
if (!collapse || data.is_empty()) {
m_text_for_rendering = data;
return;
}
// NOTE: A couple fast returns to avoid unnecessarily allocating a StringBuilder.
if (data.length() == 1) {
if (is_ascii_space(data[0])) {
if (previous_is_empty_or_ends_in_whitespace)
m_text_for_rendering = String::empty();
else {
static String s_single_space_string = " ";
m_text_for_rendering = s_single_space_string;
}
} else {
m_text_for_rendering = data;
}
return;
}
bool contains_space = false;
for (auto& c : data) {
if (is_ascii_space(c)) {
contains_space = true;
break;
}
}
if (!contains_space) {
m_text_for_rendering = data;
return;
}
StringBuilder builder(data.length());
size_t index = 0;
auto skip_over_whitespace = [&index, &data] {
while (index < data.length() && is_ascii_space(data[index]))
++index;
};
if (previous_is_empty_or_ends_in_whitespace)
skip_over_whitespace();
while (index < data.length()) {
if (is_ascii_space(data[index])) {
builder.append(' ');
++index;
skip_over_whitespace();
} else {
builder.append(data[index]);
++index;
}
}
m_text_for_rendering = builder.to_string();
}
TextNode::ChunkIterator::ChunkIterator(StringView text, LayoutMode layout_mode, bool wrap_lines, bool respect_linebreaks)
: m_layout_mode(layout_mode)
, m_wrap_lines(wrap_lines)
, m_respect_linebreaks(respect_linebreaks)
, m_utf8_view(text)
, m_iterator(m_utf8_view.begin())
{
m_last_was_space = !text.is_empty() && is_ascii_space(*m_utf8_view.begin());
}
Optional<TextNode::Chunk> TextNode::ChunkIterator::next()
{
if (m_iterator == m_utf8_view.end())
return {};
auto start_of_chunk = m_iterator;
while (m_iterator != m_utf8_view.end()) {
++m_iterator;
if (m_last_was_newline) {
// NOTE: This expression looks out for the case where we have
// multiple newlines in a row. Because every output next()
// that's a newline newline must be prepared for in advance by
// the previous next() call, we need to check whether the next
// character is a newline here as well. Otherwise, the newline
// becomes part of the next expression and causes rendering
// issues.
m_last_was_newline = m_iterator != m_utf8_view.end() && *m_iterator == '\n';
if (auto result = try_commit_chunk(start_of_chunk, m_iterator, true); result.has_value())
return result.release_value();
}
// NOTE: The checks after this need to look at the current iterator
// position, which depends on not being at the end.
if (m_iterator == m_utf8_view.end())
break;
// NOTE: When we're supposed to stop on linebreaks, we're actually
// supposed to output two chunks: "content" and "\n". Since we
// can't output two chunks at once, we store this information as a
// flag to output the newline immediately at the earliest
// opportunity.
if (m_respect_linebreaks && *m_iterator == '\n') {
m_last_was_newline = true;
if (auto result = try_commit_chunk(start_of_chunk, m_iterator, false); result.has_value()) {
return result.release_value();
}
}
if (m_wrap_lines || m_layout_mode == LayoutMode::AllPossibleLineBreaks) {
bool is_space = is_ascii_space(*m_iterator);
if (is_space != m_last_was_space) {
m_last_was_space = is_space;
if (auto result = try_commit_chunk(start_of_chunk, m_iterator, false); result.has_value()) {
return result.release_value();
}
}
}
}
if (start_of_chunk != m_utf8_view.end()) {
// Try to output whatever's left at the end of the text node.
if (auto result = try_commit_chunk(start_of_chunk, m_utf8_view.end(), false, true); result.has_value())
return result.release_value();
}
return {};
}
Optional<TextNode::Chunk> TextNode::ChunkIterator::try_commit_chunk(Utf8View::Iterator const& start, Utf8View::Iterator const& end, bool has_breaking_newline, bool must_commit) const
{
if (m_layout_mode == LayoutMode::OnlyRequiredLineBreaks && !must_commit)
return {};
auto byte_offset = m_utf8_view.byte_offset_of(start);
auto byte_length = m_utf8_view.byte_offset_of(end) - byte_offset;
if (byte_length > 0) {
auto chunk_view = m_utf8_view.substring_view(byte_offset, byte_length);
return Chunk {
.view = chunk_view,
.start = byte_offset,
.length = byte_length,
.has_breaking_newline = has_breaking_newline,
.is_all_whitespace = is_all_whitespace(chunk_view.as_string()),
};
}
return {};
}
RefPtr<Painting::Paintable> TextNode::create_paintable() const
{
return Painting::TextPaintable::create(*this);
}
}
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