fix(pdf): codepoint-aware symbol fallback; footnote cells keep fallback (#72) - #74
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June 20, 2026 12:38
…ck (#72) Two cases still emitted '?' despite the #52 Unicode fallback: (A) Non-BMP characters rendered as '??'. NeedsFallback/FontForChar/SplitFontRuns, the glyph encoder (EncodeTextAsGlyphIds/TrackCodePoints), and the WinAnsi escaper (EscapePdfString) all iterated UTF-16 code units, so a surrogate pair was treated as two characters — each half missing in every font, yielding two '?'. They now iterate Unicode codepoints: a non-BMP codepoint routes to the fallback font when covered, otherwise collapses to a single missing-glyph indicator — never '??'. (B) A footnote in a table cell disabled symbol fallback for the rest of the cell. #69's segment-based cell path (RenderCellSegments) wrapped and wrote segments directly, skipping ExpandSegmentsForFallback, so '=>'/'✓' next to a footnote regressed to base-font '?'. RenderCellSegments now runs the same fallback expansion as the body-text path. Body paragraphs were unaffected (they already go through WriteWrappedSegments). Adds PdfSymbolFallbackTests covering the single-missing-glyph behaviour for a non-BMP char, symbol fallback in footnote-bearing cells (arrow + check mark), and a plain-paragraph regression guard.
…ol-fallback # Conflicts: # CHANGELOG.md
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Fixes #72.
Problem
Two cases still emitted
?despite the #52 Unicode fallback (both render correctly in the Avalonia preview, so they're PDF-renderer-specific):??.🛇(U+1F6C7) came out as two question marks — the UTF-16 surrogate pair was iterated as two code units, each half missing in every font.⇒/✓that renders via the fallback font in a plain cell regressed to?when the same cell also had afootnote:[…]. Cross-references did not trigger it; footnotes did.Root cause & fix
(A)
NeedsFallback/FontForChar/SplitFontRuns, the glyph encoder (EncodeTextAsGlyphIds/TrackCodePoints), and the WinAnsi escaper (EscapePdfString) all iteratedchar(UTF-16 code units). They now iterate Unicode codepoints via a sharedEnumerateCodePointshelper, so a non-BMP character is one unit: it routes to the fallback font when covered, otherwise collapses to a single missing-glyph indicator — never??.(B) #69's segment-based cell path (
RenderCellSegments) wrapped and wrote segments directly, skippingExpandSegmentsForFallback— the step the body-text path (WriteWrappedSegments) runs. It now runs the same fallback expansion, so a footnote no longer disables fallback for sibling runs. (Confirmed body paragraphs were never affected.)Before → after (literal base-font text from the repro)
Prohibited ?? sign→Prohibited ? sign? K [1]→K [1](the⇒now uses the embedded fallback font)Tests
Adds
PdfSymbolFallbackTests: the single-missing-glyph behaviour for a non-BMP char (never??), symbol fallback inside footnote-bearing cells (arrow + check mark), and a plain-paragraph regression guard for the #52 behaviour. Full Release suite green (0 failures, +4 tests); the 480 PDF/conformance/parity/font tests still pass.Related: #52 (prior glyph/fallback fix), #69 (the table-cell segment path that regressed B).