When enabled the output subset conforms to the requirements for a base font to be patched by IFTB patches. IFTB is a proposed incremental font transfer patch. This new flag is set as experimental. Currently, setting this flag causes the output subset to also use long offsets for outline data in loca/glyf, gvar, CFF, and CFF2.
This change is a version of 3ae2fe2084 rebased onto head w/ tests added.
ItemVariationStore is relying on the assumption that the inner_map is populated for all output glyphs, this is not true for subsetting operations with retain gids enabled. Fixes fuzzer timeout: https://oss-fuzz.com/testcase-detail/4575222591520768.
also increase the HB_GLYF_MAX_POINTS limit to 20000 cause the test file has a
.notdef glyph which is a composite glyph and has 10176 points after
get_points() call
This previously incorrectly collected lookups that could be reached via feature variations that are dropped and not activated by the current instance position.
Also updated the script that is used to generate tests.With fonttools,
we now do instancing first and then subsetting.
With different order of subsetting and instancing operations on the same
VF file, fonttools seems to generate 2 different font files with different
glyph set.
1. do subsetting and then instancing: this seems result in a larger glyph
set in the font file. Lookups are collected from both retained features
and all possible alternate featurevariations, this leads to a larger
glyph set after glyph closurei. And instancer doesn't redo glyph
closure, it does lookups pruning only.
2. do instancing and then subsetting: lookups are collected from
features that are replaced already and possible alternate feature
variations
we should not cache visited langsys cause 2 different Record<Langsys>
could have different Tag while pointing to the same Langsys, a langsys
is redundant in Record<Langsys> A does not mean it's redundant in Record
B. Same thing for visited_script.
Also adding the number of features in the LangSys's feature list to the
visited langsys count so it's more accurate.
Plus some improvement in langsys compare()
cur_intersected_glyphs gets modified during recursion leading to incorrect filtering of sub tables in some cases. So don't use cur_intersected_glyphs. Instead just add an additional entry onto the parent_active_glyphs () stack.
Additionaly expands NotoNastaliqUrdu tests to include coverage of the issue from #3397.
- When pos_glyphs is empty, use current full glyphs set as input for
subsequent recursive closure process
- Also increase max_lookup_visit_count to 35000 cause a real font file hit
previous limit 20000 and some lookups are dropped unexpectedly
Qunxin Liu
Garret Rieger