feat: optional explicit charCodes map in svgToOtf (+ deterministic output) - #64
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AndrewDongminYoo wants to merge 4 commits into
Open
feat: optional explicit charCodes map in svgToOtf (+ deterministic output)#64AndrewDongminYoo wants to merge 4 commits into
AndrewDongminYoo wants to merge 4 commits into
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Route the name table's copyright year through MockableDateTime (head already used it) and export the MockableDateTime hook so consumers can pin created/ modified/copyright dates to a fixed instant for reproducible builds.
Address code-review findings on the charCodes feature: - Sort glyphs by assigned codepoint before building the cmap; the format 4/12 segment generator assumes ascending order, so a non-ascending charCodes map previously produced an invalid font. - Reject codepoints outside BMP 0x21..0xFFFE: the format-4 subtable is BMP-only and setUint16 silently truncates >0xFFFF, and 0x20/0xFFFF are the reserved space glyph and cmap terminator. - Reject duplicate codepoints (overlapping cmap segments). - Register charcodes_test in test_all so CI actually runs it. - Normalize cascade formatting in touched encode paths.
The BMP range check accepted UTF-16 surrogates (0xD800..0xDFFF), which are reserved and never valid Unicode scalar values; writing one into the cmap yields a font consumers cannot look up. Exclude the surrogate block explicitly and cover it with a regression test.
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What
Adds an optional
charCodesparameter tosvgToOtfso callers can assign an explicit codepoint to each glyph by name, instead of relying on the implicit sequential assignment. When omitted, behaviour is unchanged.This enables downstream tools to keep a glyph's codepoint stable across regenerations (e.g. an append-only icon set that must not remap existing icons on every build).
Commits
charCodesmap insvgToOtf— the parameter, plus deterministic glyph sorting by codepoint so the emitted cmap order is stable.MockableDateTimeso thehead(created/modified) andname(copyright year) tables can be pinned. Without this the engine stamps the wall clock into the font, so two builds of identical input produce different bytes — which breaks byte-level drift checks and reproducible builds.charCodesagainst invalid cmap generation — validates each explicit codepoint is inside the BMP (0x21..0xFFFE). The cmap format-4 subtable is BMP-only; a value above0xFFFFis silently truncated by the 16-bit encoder (setUint16(0xF1234) == 0x1234), producing a malformed cmap. Rejects duplicates and glyphs missing from the map too.0xD800..0xDFFF) sits inside the BMP range but is never a valid Unicode scalar value, so it is excluded explicitly.Tests
New
test/charcodes_test.dart(registered intest_all.dart) covers: explicit assignment, codepoint sorting, missing-glyph rejection, duplicate rejection, non-BMP rejection, and surrogate rejection. Fulldart testsuite passes; the touched files aredart analyze-clean (the repo's pre-existingexample/analyzer warnings are unchanged by this PR).Provenance & scope
Extracted from a downstream fork built for a Flutter icon-font generator. The general engine capabilities (explicit codepoints, deterministic output, cmap safety) are what I'm proposing here. An icon-font-specific policy layer — restricting explicit codepoints to the Private Use Area to match the OS/2
ulUnicodeRangecoverage that tool advertises — is intentionally kept downstream, since a general engine user may legitimately want other BMP blocks. Happy to split these commits into separate PRs or adjust scope however you prefer.