pdfcraft_fonts::helvetica_width was a fifteen-line guess by character class,
and seven crates generated appearance streams through it: annot, edit, forms,
ocr, redact, sign and xfa. Times was Helvetica x 0.9, bold was x 1.05, Courier
a flat 0.6. Against the published metrics a Times capital A is 722, so that
estimate said 600 -- a 17% error on a letter, compounding across a line.
Std14 carries the real advance widths for all fourteen faces, indexed by
character code: WinAnsiEncoding for the twelve text fonts, which is what we
write into the appearance streams we generate, and their own built-in
encodings for Symbol and ZapfDingbats. The tables are generated by joining the
published encodings with the per-glyph widths.
helvetica_width now delegates, so every call site gained exact Helvetica with
no change. The three places that faked another face by scaling it -- Family
in edit::added, the paragraph measure in edit::text, and the redaction overlay
fonts -- now select the right face instead. So does Metrics::width in
fonts::pdf, which measures existing document text when a font carries no
/Widths; that path feeds redaction's glyph removal, where a wrong width means
cutting the wrong glyphs.
Tests spot-check the table against values typed in from the specification by
hand, so it is verified against the spec rather than against whatever produced
it; plus Courier being fixed pitch everywhere, full printable-ASCII and Latin-1
coverage, Symbol and ZapfDingbats not being WinAnsi, /BaseFont aliases and
subset prefixes resolving, and hostile text staying finite.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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