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diacritics pos for glyphs sans explicit anchor tags

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minjaesong
2026-02-28 05:55:09 +09:00
parent 23e748cc88
commit 7c788eb9d8
2 changed files with 78 additions and 31 deletions
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OTFbuild/calligra_font_tests.odt
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OTFbuild/opentype_features.py
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@@ -1244,8 +1244,22 @@ def _generate_sundanese(glyphs, has):
def _generate_mark(glyphs, has):
"""
Generate GPOS mark-to-base positioning using diacritics anchors from tag column.
Marks are grouped by (writeOnTop, alignment) into separate mark classes
and lookups. Different alignments need different default base anchor
positions to match the Kotlin engine's fallback behaviour:
- ALIGN_CENTRE: base anchor at width/2
- ALIGN_RIGHT: base anchor at width
- ALIGN_LEFT/BEFORE: base anchor at 0 (mark sits at base origin)
"""
bases_with_anchors = {}
# Collect ALL non-mark glyphs as potential bases (excluding CJK
# ideographs and Braille which are unlikely to receive combining marks
# and would bloat the GPOS table).
_EXCLUDE_RANGES = (
range(0x3400, 0xA000), # CJK Unified Ideographs (Ext A + main)
range(0x2800, 0x2900), # Braille
)
all_bases = {}
marks = {}
for cp, g in glyphs.items():
@@ -1253,33 +1267,37 @@ def _generate_mark(glyphs, has):
continue
if g.props.write_on_top >= 0:
marks[cp] = g
elif any(a.x_used or a.y_used for a in g.props.diacritics_anchors):
bases_with_anchors[cp] = g
elif g.bitmap and g.props.width > 0:
if not any(cp in r for r in _EXCLUDE_RANGES):
all_bases[cp] = g
if not bases_with_anchors or not marks:
if not all_bases or not marks:
return ""
lines = []
# Group marks by writeOnTop type
mark_classes = {}
for cp, g in marks.items():
mark_type = g.props.write_on_top
if mark_type not in mark_classes:
mark_classes[mark_type] = []
mark_classes[mark_type].append((cp, g))
_align_suffix = {
SC.ALIGN_LEFT: 'l',
SC.ALIGN_RIGHT: 'r',
SC.ALIGN_CENTRE: 'c',
SC.ALIGN_BEFORE: 'b',
}
for mark_type, mark_list in sorted(mark_classes.items()):
class_name = f"@mark_type{mark_type}"
# Group marks by (writeOnTop, alignment) for separate mark classes.
mark_groups = {} # (mark_type, align) -> [(cp, g), ...]
for cp, g in marks.items():
key = (g.props.write_on_top, g.props.align_where)
mark_groups.setdefault(key, []).append((cp, g))
# Emit markClass definitions
for (mark_type, align), mark_list in sorted(mark_groups.items()):
suffix = _align_suffix.get(align, 'x')
class_name = f"@mark_t{mark_type}_{suffix}"
for cp, g in mark_list:
if g.props.align_where == SC.ALIGN_CENTRE:
if align == SC.ALIGN_CENTRE:
# Match Kotlin: anchorPoint - HALF_VAR_INIT centres the
# cell on the anchor. For U+0900-0902 the Kotlin engine
# uses (W_VAR_INIT + 1) / 2 instead (1 px nudge left).
# mark_x must match font_builder's total x_offset
# (alignment + nudge) so column `half` sits on the anchor.
# The Kotlin engine always uses W_VAR_INIT for alignment,
# even for EXTRAWIDE sheets.
bm_cols = SC.W_VAR_INIT
if 0x0900 <= cp <= 0x0902:
half = (SC.W_VAR_INIT + 1) // 2
@@ -1288,28 +1306,57 @@ def _generate_mark(glyphs, has):
x_offset = math.ceil((g.props.width - bm_cols) / 2) * SC.SCALE
x_offset -= g.props.nudge_x * SC.SCALE
mark_x = x_offset + half * SC.SCALE
elif align == SC.ALIGN_RIGHT:
# Match Kotlin: mark at base anchor - W_VAR_INIT.
# The contour x_offset already includes (width - W_VAR_INIT),
# so mark_x just needs the nudge_x component.
mark_x = g.props.nudge_x * SC.SCALE
else:
mark_x = ((g.props.width + 1) // 2) * SC.SCALE
# ALIGN_LEFT / ALIGN_BEFORE: mark sits at base origin.
mark_x = 0
mark_y = SC.ASCENT
lines.append(
f"markClass {glyph_name(cp)} <anchor {mark_x} {mark_y}> {class_name};"
)
# Define lookups at top level so they can be referenced from
# multiple script registrations in the mark feature.
# Generate one lookup per (mark_type, align) group.
lookup_names = []
for mark_type, mark_list in sorted(mark_classes.items()):
class_name = f"@mark_type{mark_type}"
lookup_name = f"mark_type{mark_type}"
for (mark_type, align), mark_list in sorted(mark_groups.items()):
suffix = _align_suffix.get(align, 'x')
class_name = f"@mark_t{mark_type}_{suffix}"
lookup_name = f"mark_t{mark_type}_{suffix}"
lines.append(f"lookup {lookup_name} {{")
for cp, g in sorted(bases_with_anchors.items()):
anchor = g.props.diacritics_anchors[mark_type] if mark_type < 6 else None
if anchor and (anchor.x_used or anchor.y_used):
# Match Kotlin: when x_used is false, default to width / 2
ax = (anchor.x if anchor.x_used else g.props.width // 2) * SC.SCALE
ay = (SC.ASCENT // SC.SCALE - anchor.y) * SC.SCALE
lines.append(f" pos base {glyph_name(cp)} <anchor {ax} {ay}> mark {class_name};")
for cp, g in sorted(all_bases.items()):
anchor = (g.props.diacritics_anchors[mark_type]
if mark_type < len(g.props.diacritics_anchors)
else None)
has_explicit = anchor and (anchor.x_used or anchor.y_used)
if align in (SC.ALIGN_LEFT, SC.ALIGN_BEFORE):
# Kotlin ignores base anchors for these alignments;
# the mark always sits at posX[base].
ax = 0
ay = SC.ASCENT
elif has_explicit:
ax = (anchor.x if anchor.x_used
else g.props.width // 2) * SC.SCALE
ay = ((SC.ASCENT // SC.SCALE - anchor.y) * SC.SCALE
if anchor.y_used else SC.ASCENT)
elif align == SC.ALIGN_CENTRE:
ax = (g.props.width // 2) * SC.SCALE
ay = SC.ASCENT
elif align == SC.ALIGN_RIGHT:
ax = g.props.width * SC.SCALE
ay = SC.ASCENT
else:
ax = 0
ay = SC.ASCENT
lines.append(
f" pos base {glyph_name(cp)}"
f" <anchor {ax} {ay}> mark {class_name};"
)
lines.append(f"}} {lookup_name};")
lines.append("")