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Auto merge of #26447 - jdm:white-space-2020, r=nox
Layout 2020: Implement basic white-space: pre support With these changes `<pre>` and `<br>` preserve spaces and force line breaks appropriately. --- - [x] `./mach build -d` does not report any errors - [x] `./mach test-tidy` does not report any errors - [x] These changes fix #26440 - [x] There are tests for these changes
This commit is contained in:
commit
6a3c3a4e18
53 changed files with 128 additions and 135 deletions
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@ -20,6 +20,7 @@ use rayon_croissant::ParallelIteratorExt;
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use servo_arc::Arc;
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use std::borrow::Cow;
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use std::convert::{TryFrom, TryInto};
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use style::computed_values::white_space::T as WhiteSpace;
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use style::properties::longhands::list_style_position::computed_value::T as ListStylePosition;
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use style::properties::ComputedValues;
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use style::selector_parser::PseudoElement;
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@ -293,60 +294,96 @@ where
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}
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fn handle_text(&mut self, info: &NodeAndStyleInfo<Node>, input: Cow<'dom, str>) {
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let (leading_whitespace, mut input) = self.handle_leading_whitespace(&input);
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if leading_whitespace || !input.is_empty() {
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// This text node should be pushed either to the next ongoing
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// inline level box with the parent style of that inline level box
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// that will be ended, or directly to the ongoing inline formatting
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// context with the parent style of that builder.
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let inlines = self.current_inline_level_boxes();
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// Skip any leading whitespace as dictated by the node's style.
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let white_space = info.style.get_inherited_text().white_space;
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let (preserved_leading_whitespace, mut input) =
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self.handle_leading_whitespace(&input, white_space);
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let mut new_text_run_contents;
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let output;
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if !preserved_leading_whitespace && input.is_empty() {
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return;
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}
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{
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let mut last_box = inlines.last_mut().map(|last| last.borrow_mut());
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let last_text = last_box.as_mut().and_then(|last| match &mut **last {
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InlineLevelBox::TextRun(last) => Some(&mut last.text),
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_ => None,
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});
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// This text node should be pushed either to the next ongoing
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// inline level box with the parent style of that inline level box
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// that will be ended, or directly to the ongoing inline formatting
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// context with the parent style of that builder.
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let inlines = self.current_inline_level_boxes();
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if let Some(text) = last_text {
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// Append to the existing text run
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new_text_run_contents = None;
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output = text;
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} else {
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new_text_run_contents = Some(String::new());
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output = new_text_run_contents.as_mut().unwrap();
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}
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let mut new_text_run_contents;
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let output;
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if leading_whitespace {
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output.push(' ')
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}
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loop {
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if let Some(i) = input.bytes().position(|b| b.is_ascii_whitespace()) {
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{
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let mut last_box = inlines.last_mut().map(|last| last.borrow_mut());
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let last_text = last_box.as_mut().and_then(|last| match &mut **last {
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InlineLevelBox::TextRun(last) => Some(&mut last.text),
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_ => None,
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});
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if let Some(text) = last_text {
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// Append to the existing text run
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new_text_run_contents = None;
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output = text;
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} else {
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new_text_run_contents = Some(String::new());
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output = new_text_run_contents.as_mut().unwrap();
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}
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if preserved_leading_whitespace {
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output.push(' ')
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}
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match (
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white_space.preserve_spaces(),
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white_space.preserve_newlines(),
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) {
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// All whitespace is significant, so we don't need to transform
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// the input at all.
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(true, true) => {
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output.push_str(input);
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},
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// There are no cases in CSS where where need to preserve spaces
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// but not newlines.
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(true, false) => unreachable!(),
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// Spaces are not significant, but newlines might be. We need
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// to collapse non-significant whitespace as appropriate.
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(false, preserve_newlines) => loop {
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// If there are any spaces that need preserving, split the string
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// that precedes them, collapse them into a single whitespace,
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// then process the remainder of the string independently.
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if let Some(i) = input
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.bytes()
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.position(|b| b.is_ascii_whitespace() && (!preserve_newlines || b != b'\n'))
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{
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let (non_whitespace, rest) = input.split_at(i);
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output.push_str(non_whitespace);
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output.push(' ');
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if let Some(i) = rest.bytes().position(|b| !b.is_ascii_whitespace()) {
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// Find the first byte that is either significant whitespace or
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// non-whitespace to continue processing it.
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if let Some(i) = rest.bytes().position(|b| {
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!b.is_ascii_whitespace() || (preserve_newlines && b == b'\n')
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}) {
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input = &rest[i..];
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} else {
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break;
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}
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} else {
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// No whitespace found, so no transformation is required.
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output.push_str(input);
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break;
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}
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}
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},
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}
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}
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if let Some(text) = new_text_run_contents {
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inlines.push(ArcRefCell::new(InlineLevelBox::TextRun(TextRun {
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tag: Tag::from_node_and_style_info(info),
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parent_style: Arc::clone(&info.style),
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text,
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})))
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}
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if let Some(text) = new_text_run_contents {
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inlines.push(ArcRefCell::new(InlineLevelBox::TextRun(TextRun {
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tag: Tag::from_node_and_style_info(info),
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parent_style: Arc::clone(&info.style),
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text,
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})))
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}
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}
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}
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@ -359,10 +396,14 @@ where
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///
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/// * Whether this text run has preserved (non-collapsible) leading whitespace
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/// * The contents starting at the first non-whitespace character (or the empty string)
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fn handle_leading_whitespace<'text>(&mut self, text: &'text str) -> (bool, &'text str) {
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fn handle_leading_whitespace<'text>(
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&mut self,
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text: &'text str,
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white_space: WhiteSpace,
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) -> (bool, &'text str) {
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// FIXME: this is only an approximation of
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// https://drafts.csswg.org/css2/text.html#white-space-model
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if !text.starts_with(|c: char| c.is_ascii_whitespace()) {
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if !text.starts_with(|c: char| c.is_ascii_whitespace()) || white_space.preserve_spaces() {
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return (false, text);
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}
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@ -756,13 +756,21 @@ impl TextRun {
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let mut glyphs = vec![];
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let mut advance_width = Length::zero();
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let mut last_break_opportunity = None;
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let mut force_line_break = false;
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// Fit as many glyphs within a single line as possible.
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loop {
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let next = runs.next();
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// If there are no more text runs we still need to check if the last
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// run was a forced line break
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if next
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.as_ref()
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.map_or(true, |run| run.glyph_store.is_whitespace())
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{
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// If this run exceeds the bounds of the containing block, then
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// we need to attempt to break the line.
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if advance_width > ifc.containing_block.inline_size - ifc.inline_position {
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// Reset the text run iterator to the last whitespace if possible,
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// to attempt to re-layout the most recent glyphs on a new line.
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if let Some((len, width, iter)) = last_break_opportunity.take() {
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glyphs.truncate(len);
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advance_width = width;
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@ -774,10 +782,24 @@ impl TextRun {
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if let Some(run) = next {
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if run.glyph_store.is_whitespace() {
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last_break_opportunity = Some((glyphs.len(), advance_width, runs.clone()));
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// If this whitespace ends with a newline, we need to check if
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// it's meaningful within the current style. If so, we force
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// a line break immediately.
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let last_byte = self.text.as_bytes().get(run.range.end().to_usize() - 1);
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if last_byte == Some(&b'\n') &&
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self.parent_style
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.get_inherited_text()
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.white_space
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.preserve_newlines()
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{
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force_line_break = true;
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break;
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}
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}
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glyphs.push(run.glyph_store.clone());
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advance_width += Length::from(run.glyph_store.total_advance());
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} else {
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// No more runs, so we can end the line.
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break;
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}
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}
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@ -812,7 +834,8 @@ impl TextRun {
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glyphs,
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text_decoration_line: ifc.current_nesting_level.text_decoration_line,
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}));
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if runs.as_slice().is_empty() {
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// If this line is being broken because of a trailing newline, we can't ignore it.
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if runs.as_slice().is_empty() && !force_line_break {
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break;
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} else {
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// New line
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