Right-to-left text and hyphenation

Right-to-left text: Arabic and Hebrew

Arabic and Hebrew are laid out right to left and shaped like browsers do, with PdfPecker's own implementation of the Unicode Bidirectional Algorithm (UAX #9, passing all of Unicode's conformance tests) and of OpenType shaping (GSUB and GPOS, following HarfBuzz). Arabic letters join, lam-alef and other ligatures form, and harakat and Hebrew points are placed on their letters by the font's mark positioning. Mixed text (an English product name or a number inside an Arabic sentence) is put in the right order, and brackets are mirrored. Register a font that has the script, then set the direction with the dir attribute or CSS direction:

var options = new PdfOptions();
options.Fonts.AddFile("fonts/NotoNaskhArabic-Regular.ttf");
byte[] pdf = HtmlToPdf.Convert("""
    <html dir="rtl" lang="ar"><body style="font-family: 'Noto Naskh Arabic'">
      <h1>فاتورة رقم ٢٠٢٦/١٥</h1>
      <p>المبلغ الإجمالي: 1,250.00 DKK</p>
    </body></html>
    """, options);

In a right-to-left block, text aligns right (text-align: start), and table columns, flex rows, grid columns and list markers run from the right. dir="auto", <bdi> and <bdo> work as in browsers, and so do unicode-bidi, text-align: start/end and the logical margin and padding properties (margin-inline-start, padding-inline-end, ...). text-overflow: ellipsis and line-clamp cut right-to-left lines at their left end. SVG <text> is reordered and shaped too, with direction deciding which way a text chunk runs from its x. Copied or extracted text gives back the original characters in logical order. A font without OpenType Arabic features is shaped with the Unicode presentation forms instead.

Hyphenation

hyphens: auto hyphenates words with the TeX hyphenation patterns (Liang's algorithm) of the text's language: the nearest lang attribute, else PdfOptions.Language. As in Chrome, a word is hyphenated only where it does not fit on its line, and a hyphen (or the hyphenate-character) is shown at the break. Words shorter than five letters, words with digits or other non-letters inside, URLs and e-mail addresses, and capitalized English words are not hyphenated, and a word with ­ breaks only there. Patterns for English (US patterns for every en tag), Danish, German, Dutch and Norwegian (nb, nn, no) are built in and loaded on first use; others can be supplied as TeX pattern files, such as those of the hyph-utf8 project:

var options = new PdfOptions
{
    // Your own patterns for a language (they take precedence over the built-in ones).
    Hyphenation = new Dictionary<string, HyphenationPatterns>
    {
        ["sv"] = new HyphenationPatterns(File.ReadAllText("hyph-sv.tex"), leftMin: 2, rightMin: 2),
    },
};
byte[] pdf = HtmlToPdf.Convert("""
    <html lang="da"><body style="hyphens: auto; text-align: justify">
      <p>Arbejdsmarkedsbidraget betales af lønmodtageren.</p>
      <p lang="sv">Avstavning med egna mönster.</p>
    </body></html>
    """, options);