Standard fonts in pdf-lib cannot encode certain characters outside WinAnsi

[VladyslavLytvynenko22]

What were you trying to do?

While generating a PDF with pdf-lib, I encountered an issue when trying to render text that includes characters not supported by WinAnsi encoding. For example, letters such as Т (0x0422) cannot be encoded.

Steps to Reproduce:

Create a PDF using pdf-lib.

Add a text field or text content with characters outside WinAnsi (e.g., Т).

Save the PDF.

Expected Behavior:
The library should support rendering text with a broader character set (e.g., via embedding a font with extended Unicode support).

Actual Behavior:
Throws an error:

index.tsx:119 Error: WinAnsi cannot encode "Т" (0x0422)
at Encoding.encodeUnicodeCodePoint (Encoding.js:18:1)
at StandardFontEmbedder.encodeTextAsGlyphs (StandardFontEmbedder.ts:124:1)
at StandardFontEmbedder.encodeText (StandardFontEmbedder.ts:50:1)
at PDFFont.encodeText (PDFFont.ts:72:1)
at layoutSinglelineText (layout.ts:324:1)
at defaultTextFieldAppearanceProvider (appearances.ts:475:1)
at PDFTextField.updateWidgetAppearance (PDFTextField.ts:823:1)
at PDFTextField.updateAppearances (PDFTextField.ts:812:1)
at PDFTextField.defaultUpdateAppearances (PDFTextField.ts:783:1)
at PDFForm.updateFieldAppearances (PDFForm.ts:647:1)

Proposal:
Consider adding support for fonts that include extended Unicode characters (beyond WinAnsi), so text with a wider range of letters can be properly embedded and rendered.

How did you attempt to do it?

const pdfDoc = await PDFDocument.load(fileBytes);
const form = pdfDoc.getForm();
const field = form.getTextField("test");
field.setText("Тест");
await pdfDoc.save();

Error: WinAnsi cannot encode "Т" (0x0422)
at Encoding.encodeUnicodeCodePoint (Encoding.js:18:1)
at StandardFontEmbedder.encodeTextAsGlyphs (StandardFontEmbedder.ts:124:1)
at StandardFontEmbedder.encodeText (StandardFontEmbedder.ts:50:1)
at PDFFont.encodeText (PDFFont.ts:72:1)
...

What actually happened?

Workaround:
Using a custom font with fontkit works correctly:

pdfDoc.registerFontkit(fontkit);
const fontBytes = await getLiberationSansFont();
const customFont = await pdfDoc.embedFont(fontBytes);

const formField = form.getTextField("test");
formField.setText("Тест");
formField.updateAppearances(customFont);

What did you expect to happen?

Proposal:
Consider embedding at least one font with broader Unicode support by default (e.g., LiberationSans, NotoSans), or provide an easier mechanism to fall back from WinAnsi to a Unicode-capable font.

like
pdfDoc.embedFont(StandardFonts.LiberationSansUnicode);

How can we reproduce the issue?

const pdfDoc = await PDFDocument.load(fileBytes);
const form = pdfDoc.getForm();
const field = form.getTextField("test");
field.setText("Тест");
await pdfDoc.save();

Error: WinAnsi cannot encode "Т" (0x0422)
at Encoding.encodeUnicodeCodePoint (Encoding.js:18:1)
at StandardFontEmbedder.encodeTextAsGlyphs (StandardFontEmbedder.ts:124:1)
at StandardFontEmbedder.encodeText (StandardFontEmbedder.ts:50:1)
at PDFFont.encodeText (PDFFont.ts:72:1)
...

Version

1.17.1

What environment are you running pdf-lib in?

Other

Checklist

• My report includes a Short, Self Contained, Correct (Compilable) Example.
• I have attached all PDFs, images, and other files needed to run my SSCCE.

Additional Notes

No response