Hyphenation on soft hyphens is broken

[wojtekmaj]

Describe the bug

Text with unicode shy characters doesn't seem to be properly split, regardless whether custom hyphenation callback has been provided or not.

Furthermore, when custom hyphenator (splitting the text on shy) is provided, the text appears to be cut - and the number of characters cut from the text corresponds to the number of soft hyphens found in the text:

Font.registerHyphenationCallback(word => word.split('\u00ad'));

When hyphenation is disabled by providing an "empty" hyphenation callback, the text is rendered in one line with shy characters visible, which should not be the case:

Font.registerHyphenationCallback(word => [word])

After investigation I've noticed that the number of characters from the hyphenation callback must match the input length exactly in order for the text not to be cut. This, however, just like not providing custom hyphenation callback, causes double hyphens:

Font.registerHyphenationCallback(
  (word) => {
    const parts = [];
    let part = '';
    for (let i = 0; i < word.length; i++) {
      const char = word[i];
      if (char === '\u00ad') {
        parts.push(part + char);
        part = '';
      } else {
        part += char;
      }
    }
    if (part) {
      parts.push(part);
    }
    return parts;
  }
);

To Reproduce

const shy = '\u00ad';

const Test = () => (
  <Document>
    <Page style={styles.body}>
      <Text style={styles.text}>{`Potentieel broeikas${shy}gas${shy}emissie${shy}rapport`}</Text>
    </Page>
  </Document>
);

const styles = StyleSheet.create({
  body: { padding: 20 },
  text: {
    width: 100,
    border: '1px solid red',
  },
});

Font.registerHyphenationCallback(
  (word) => console.log(word, '=>', word.split('\u00ad')) || word.split('\u00ad'),
);

ReactPDF.render(<Test />);

https://v4.react-pdf.org/repl?code=3187b0760ce02e004101604f18178607200e815c00cb810c0137406e00a1cd1258015014da546002804a5403e57c98600780088860d802dbd30513af3e020028100e6f4e1444006de8a00ded13630074008c41144017c65cb9fc1800f58fab6ee746a3d47567400379203ca4012de9e834618c009c41e88201ac08200048f4902c951252112de8c482202042b2d32208001cca4122a07c2df801e81da564f81b1455ac05eb854424a464d828a9c098dc21980195d4b427e142a10d8123e8083c5875654dcc00b8607460cb888882c09576009970602c0069643d1d76366c01dc8288a1e1760119f0ee6d4c91223d122bb7437ccaf63808034ef1832c48ff6b9dc2c834a000c5c00b65929f21e488002510653998156417000184081a0d31808c0388b1642c17954881c14371a810187d10c1a1012959ec9b860b9e8315b2818608195615016160f084121b038001f0d4c1a544597ca828ae57e188e8361dcd1e400128ad805079209d186659818191161d918b07aa70d1400000

Expected behavior

Screenshots

Split hyphenation:

No hyphenation:

Fancy hyphenation:

Desktop (please complete the following information):

• OS: macOS
• Browser: Chrome
• React-pdf version: 4.1.6