[myanmar] Implement Zawgyi shaper

Enabled if script tag 'Qaag' is passed to HarfBuzz.  Disables mark
advance-zeroing and fallback mark-positioning.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1162

src/hb-ot-shape-complex-myanmar.cc

@@ -413,3 +413,25 @@ const hb_ot_complex_shaper_t _hb_ot_complex_shaper_myanmar_old =
   HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
   true, /* fallback_position */
 };
+
+
+/* Ugly Zawgyi encoding.
+ * Disable all auto processing.
+ * https://github.com/harfbuzz/harfbuzz/issues/1162 */
+const hb_ot_complex_shaper_t _hb_ot_complex_shaper_myanmar_zawgyi =
+{
+  nullptr, /* collect_features */
+  nullptr, /* override_features */
+  nullptr, /* data_create */
+  nullptr, /* data_destroy */
+  nullptr, /* preprocess_text */
+  nullptr, /* postprocess_glyphs */
+  HB_OT_SHAPE_NORMALIZATION_MODE_NONE,
+  nullptr, /* decompose */
+  nullptr, /* compose */
+  nullptr, /* setup_masks */
+  HB_TAG_NONE, /* gpos_tag */
+  nullptr, /* reorder_marks */
+  HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
+  false, /* fallback_position */
+};

src/hb-ot-shape-complex.hh

@@ -58,6 +58,7 @@ enum hb_ot_shape_zero_width_marks_type_t {
   HB_COMPLEX_SHAPER_IMPLEMENT (khmer) \
   HB_COMPLEX_SHAPER_IMPLEMENT (myanmar) \
   HB_COMPLEX_SHAPER_IMPLEMENT (myanmar_old) \
+  HB_COMPLEX_SHAPER_IMPLEMENT (myanmar_zawgyi) \
   HB_COMPLEX_SHAPER_IMPLEMENT (thai) \
   HB_COMPLEX_SHAPER_IMPLEMENT (use) \
   /* ^--- Add new shapers here */
@@ -374,6 +375,10 @@ hb_ot_shape_complex_categorize (const hb_ot_shape_planner_t *planner)
 	return &_hb_ot_complex_shaper_default;
       else
 	return &_hb_ot_complex_shaper_use;
+
+    /* https://github.com/harfbuzz/harfbuzz/issues/1162 */
+    case HB_SCRIPT_MYANMAR_ZAWGYI:
+      return &_hb_ot_complex_shaper_myanmar_zawgyi;
   }
 }
 

src/hb.hh

@@ -478,6 +478,14 @@ _hb_memalign(void **memptr, size_t alignment, size_t size)
 #endif
 
 
+/*
+ * For lack of a better place, put Zawgyi script hack here.
+ * https://github.com/harfbuzz/harfbuzz/issues/1162
+ */
+
+#define HB_SCRIPT_MYANMAR_ZAWGYI	((hb_script_t) HB_TAG ('Q','a','a','g'))
+
+
 /* Headers we include for everyone.  Keep sorted.  They express dependency amongst
  * themselves, but no other file should include them.*/
 #include "hb-atomic.hh"

test/shaping/data/in-house/Makefile.sources

@@ -37,6 +37,7 @@ TESTS = \
 	tests/mark-filtering-sets.tests \
 	tests/mongolian-variation-selector.tests \
 	tests/myanmar-syllable.tests \
+	tests/myanmar-zawgyi.tests \
 	tests/none-directional.tests \
 	tests/rand.tests \
 	tests/spaces.tests \

test/shaping/data/in-house/tests/myanmar-zawgyi.tests

@@ -0,0 +1 @@
+../fonts/ab14b4eb9d7a67e293f51d30d719add06c9d6e06.ttf:--script=Qaag:U+1000,U+103A,U+1004,U+1037,U+1039,U+1041:[Ka=0+2217|Ya-Semivowel=0+286|Nga=2+1247|Dot Below=2+0|Virama-Killer=2+0|One-Myanmar=5+1247]