pdfFontEncoding

Resolution of a simple font's /Encoding entry — ISO 32000-2 §9.6.5.

Module pdfFontEncoding | Source packages/front/office/pdf/src/font/encoding.js | Deps pdfErrors | Worker-safe yes

Builds a 256-entry table of glyph names (or null for unmapped slots) from a PDF /Encoding entry. Three accepted shapes:

• absent → StandardEncoding.
• name: /WinAnsiEncoding, /MacRomanEncoding, /MacExpertEncoding, /StandardEncoding, /SymbolEncoding, /ZapfDingbatsEncoding.
• dict: { BaseEncoding?: name, Differences?: array } — overlays slots on top of the base table.

The module is pure: it does not know the named tables themselves. The caller passes lookupNamed (typically @awacloud/fonts/encodings#lookupEncoding).

Resolve

const enc = runtime.resolve('pdfFontEncoding');
// Returns: { resolveEncoding }

API

Differences format (§9.6.5.4)

Array interleaving ints (starting slot) and names (consecutive glyphs):

[ 1 /a /b /c   65 /A /B ]
  └─ slot 1=a, 2=b, 3=c
                  └─ slot 65=A, 66=B

Examples

Named encoding

const enc = runtime.resolve('pdfFontEncoding');
const table = enc.resolveEncoding(
    { type: 'name', value: 'WinAnsiEncoding' },
    lookupNamed
);
table[0x41];   // 'A'
table[0x80];   // 'Euro' (WinAnsi)

Encoding with Differences

const entry = obj.dict({
    BaseEncoding: obj.name('WinAnsiEncoding'),
    Differences: obj.array([
        obj.int(1), obj.name('exclamdown'), obj.name('cent')
    ])
});
const table = enc.resolveEncoding(entry, lookupNamed);
table[1];  // 'exclamdown'
table[2];  // 'cent'

Absent encoding → Standard

const table = enc.resolveEncoding(null, lookupNamed);
// → StandardEncoding

Errors

See also

• pdfFont — carries the encoding field.
• pdfType3 — accepts the same format.
• pdfText — extractText consumes the mapping.