Improve distribution and width of furigana

crates/core/src/document/html/engine.rs

@@ -853,7 +853,9 @@ impl Engine {
  font.plan(" 0.", None, None)
  };
  let mut start_index = 0;
+ let mut ruby_start_index = 0;
  for (end_index, _is_hardbreak) in LineBreakIterator::new(text) {
+ let text_len = text[start_index..end_index].chars().count();
  for chunk in text[start_index..end_index].split_inclusive(char::is_whitespace) {
  if let Some((i, c)) = chunk.char_indices().next_back() {
  let j = i + if c.is_whitespace() { 0 } else { c.len_utf8() };
@@ -870,13 +872,16 @@ impl Engine {
  };
  plan.space_out(style.letter_spacing);
 
+ let ruby_chars = style.ruby.clone().map(|r| r.chars().count());
+ let ruby_chars_use = ruby_chars.map(|c| std::cmp::min(c.div_ceil(text_len), (c - ruby_start_index).div_ceil(text_len)));
+
  items.push(ParagraphItem::Box {
  width: plan.width,
  data: ParagraphElement::Text(TextElement {
  offset: local_offset,
  language: style.language.clone(),
  text: buf.to_string(),
- ruby: if start_index == 0 { style.ruby.clone() } else { None },
+ ruby: style.ruby.clone().map(|r| r.chars().skip(ruby_start_index).take(ruby_chars_use.unwrap()).collect()),
  plan,
  font_features: style.font_features.clone(),
  font_kind: style.font_kind,
@@ -889,6 +894,8 @@ impl Engine {
  uri: style.uri.clone(),
  }),
  });
+
+ ruby_start_index += ruby_chars_use.unwrap_or(0);
  }
  if c.is_whitespace() {
  if c == '\n' && parent_style.retain_whitespace {
@@ -1279,7 +1286,7 @@ impl Engine {
 
  for i in last_index..index {
  match items[i] {
- ParagraphItem::Box { ref data, width } => {
+ ParagraphItem::Box { ref data, mut width } => {
  match data {
  ParagraphElement::Text(element) => {
  let pt = pt!(position.x, position.y - element.vertical_align);
@@ -1317,6 +1324,9 @@ impl Engine {
  font.set_size(element.font_size / 2, self.dpi);
  font.plan(ruby.to_string(), None, style.font_features.as_deref())
  };
+ if width < ruby_plan.width {
+ width = ruby_plan.width;
+ }
  page.push(DrawCommand::ExtraText(TextCommand {
  offset: element.offset + root_data.start_offset,
  position: pt + pt!(0, -ascender),