From ea6dbcf627e9a440590d0d35ff16ca7ae60d5719 Mon Sep 17 00:00:00 2001 From: eunhhu Date: Mon, 28 Sep 2026 16:13:58 +0100 Subject: Kern with class subtables too (kern formats 2 and 3) The kern table's class subtables, OpenType's and Apple's, as HarfBuzz reads them (hb-aat-layout-kerx-table.hh, hb-ot-kern-table.hh): format 2's class tables give byte offsets into a kerning array, format 3's byte classes index a value list. Both go through the same pass as pairs (marks skipped, the kerning split between the pair). Format 2 filters the glyphs by the class tables' digests, as HarfBuzz's accelerator does, so a digest's false positive reads class 0 there too; what a subtable reads must lie within it, the last one's within the table. The build checks the subtables as HarfBuzz's sanitizer does, and still refuses state machines (format 1) and cross-stream kerning. text/test-kern.py makes fonts with format 2 and 3 subtables in every order, with the edge cases that reading has (value 1, glyphs outside a table, offsets below the array or odd, values past a subtable's or the table's end, classes and indexes past their counts): 24 fonts, 96 plans, the same as HarfBuzz. make check runs it where fontTools is. HarfBuzz's suite: 5017 of 5199 the same. --- Makefile | 2 ++ 1 file changed, 2 insertions(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 707dbbc..94b7ac7 100644 --- a/Makefile +++ b/Makefile @@ -90,6 +90,8 @@ check: $(BUILD)/vega $(BUILD)/vega-symbols $(BUILD)/vega-surface.so $(BUILD)/tes if [ -f $(SHAPED_FONT) ]; then $(BUILD)/vega-symbols build --font $(SHAPED_FONT) --codes $(SHAPED_CODES) \ --shape Latn,Grek,Cyrl,Hebr,Arab,Zyyy --runs 5000 -o $(BUILD)/shaped.vsym && \ $(BUILD)/test-layout $(BUILD)/shaped.vsym; else echo "no $(SHAPED_FONT): shaping tests skipped"; fi + if [ -f $(SHAPED_FONT) ] && python3 -c 'import fontTools' 2>/dev/null; then \ + python3 text/test-kern.py $(BUILD)/vega-symbols $(SHAPED_FONT); else echo "no fontTools: kern class tests skipped"; fi $(MAKE) -C $(AUP) build/aup $(MAKE) -C $(PURE) build/pure-serve python3 tests/check.py --vega $(BUILD)/vega --symbols $(BUILD)/vega-symbols --aup $(AUP)/build/aup --serve $(PURE)/build/pure-serve -- cgit v1.2.3