Handle many unicode caracters with PDFBox

A better solution than waiting for a font or guessing a text's language is to have a multitude of fonts and selecting the correct font on a glyph-by-glyph base.

You already found the Google Noto Fonts which are a good base collection of fonts for this task.

Unfortunately, though, Google publishes the Noto CJK fonts only as OpenType fonts (.otf), not as TrueType fonts (.ttf), a policy that isn't likely to change, cf. the Noto fonts issue 249 and others. On the other hand PDFBox does not support OpenType fonts and isn't actively working on OpenType support either, cf. PDFBOX-2482.

Thus, one has to convert the OpenType font somehow to TrueType. I simply took the file shared by djmilch in his blog post FREE FONT NOTO SANS CJK IN TTF.

Font selection per character

So you essentially need a method which checks your text character by character and dissects it into chunks which can be drawn using the same font.

Unfortunately I don't see a better method to ask a PDFBox PDFont whether it knows a glyph for a given character than to actually try to encode the character and consider a IllegalArgumentException a "no".

I, therefore, implemented that functionality using the following helper class TextWithFont and method fontify:

class TextWithFont {
    final String text;
    final PDFont font;

    TextWithFont(String text, PDFont font) {
        this.text = text;
        this.font = font;
    }

    public void show(PDPageContentStream canvas, float fontSize) throws IOException {
        canvas.setFont(font, fontSize);
        canvas.showText(text);
    }
}

(AddTextWithDynamicFonts inner class)

List<TextWithFont> fontify(List<PDFont> fonts, String text) throws IOException {
    List<TextWithFont> result = new ArrayList<>();
    if (text.length() > 0) {
        PDFont currentFont = null;
        int start = 0;
        for (int i = 0; i < text.length(); ) {
            int codePoint = text.codePointAt(i);
            int codeChars = Character.charCount(codePoint);
            String codePointString = text.substring(i, i + codeChars);
            boolean canEncode = false;
            for (PDFont font : fonts) {
                try {
                    font.encode(codePointString);
                    canEncode = true;
                    if (font != currentFont) {
                        if (currentFont != null) {
                            result.add(new TextWithFont(text.substring(start, i), currentFont));
                        }
                        currentFont = font;
                        start = i;
                    }
                    break;
                } catch (Exception ioe) {
                    // font cannot encode codepoint
                }
            }
            if (!canEncode) {
                throw new IOException("Cannot encode '" + codePointString + "'.");
            }
            i += codeChars;
        }
        result.add(new TextWithFont(text.substring(start, text.length()), currentFont));
    }
    return result;
}

(AddTextWithDynamicFonts method)

Example use

Using the method and the class above like this

String latinText = "This is latin text";
String japaneseText = "これは日本語です";
String mixedText = "Tこhれiはs日 本i語sで すlatin text";

generatePdfFromStringImproved(latinText).writeTo(new FileOutputStream("Cccompany-Latin-Improved.pdf"));
generatePdfFromStringImproved(japaneseText).writeTo(new FileOutputStream("Cccompany-Japanese-Improved.pdf"));
generatePdfFromStringImproved(mixedText).writeTo(new FileOutputStream("Cccompany-Mixed-Improved.pdf"));

(AddTextWithDynamicFonts test testAddLikeCccompanyImproved)

ByteArrayOutputStream generatePdfFromStringImproved(String content) throws IOException {
    try (   PDDocument doc = new PDDocument();
            InputStream notoSansRegularResource = AddTextWithDynamicFonts.class.getResourceAsStream("NotoSans-Regular.ttf");
            InputStream notoSansCjkRegularResource = AddTextWithDynamicFonts.class.getResourceAsStream("NotoSansCJKtc-Regular.ttf")   ) {
        PDType0Font notoSansRegular = PDType0Font.load(doc, notoSansRegularResource);
        PDType0Font notoSansCjkRegular = PDType0Font.load(doc, notoSansCjkRegularResource);
        List<PDFont> fonts = Arrays.asList(notoSansRegular, notoSansCjkRegular);

        List<TextWithFont> fontifiedContent = fontify(fonts, content);

        PDPage page = new PDPage();
        doc.addPage(page);
        try (   PDPageContentStream contentStream = new PDPageContentStream(doc, page)) {
            contentStream.beginText();
            for (TextWithFont textWithFont : fontifiedContent) {
                textWithFont.show(contentStream, 12);
            }
            contentStream.endText();
        }
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        doc.save(os);
        return os;
    }
}

(AddTextWithDynamicFonts helper method)

I get

• for latinText = "This is latin text"

  

• for japaneseText = "これは日本語です"

  

• and for mixedText = "Tこhれiはs日 本i語sで すlatin text"

  

Some asides

• I retrieved the fonts as Java resources but you can use any kind of InputStream for them.

• The font selection mechanism above can quite easily be combined with the line breaking mechanism shown in this answer and the justification extension thereof in this answer