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import logging
def shaper_inputs(self):
"""Returns a list of potential glyphs to determine whether to test if this
rule applies at a given point."""
return [self.bases.keys(), self.marks.keys()]
def find_base_backwards(self, buf, ix):
"""Looks backwards in a buffer from index ``ix`` to find the nearest base."""
start_ix = ix
ix = ix - 1
while ix >= 0:
if buf[ix].glyph in self.bases.keys():
# Check for unhelpful stuff in between
my_category = buf[ix].category[0]
for i in range(ix + 1, start_ix):
if buf[i].category[0] == my_category or buf[i].category[0] == "unknown":
# Oops, we skipped over another %s to get here
return None
return ix
ix = ix - 1
return None
def would_apply_at_position(self, buf, ix, namedclasses={}):
"""Tests to see if this rule would apply at position ``ix`` of the buffer."""
from fontFeatures.shaperLib.Rule import _expand_slot
logging.getLogger("fontFeatures.shaperLib").debug(
"Testing if rule would apply at position %i" % (ix)
)
if namedclasses:
marks = _expand_slot(self.marks.keys(), namedclasses)
bases = _expand_slot(self.bases.keys(), namedclasses)
else:
marks = self.marks.keys()
bases = self.bases.keys()
if self.is_cursive:
if ix == 0:
logging.getLogger("fontFeatures.shaperLib").debug(
" * No, it has no adjacent glyph"
)
return False
# We will sort it out later
# logging.getLogger("fontFeatures.shaperLib").debug(" * Yes, %s/%s is a pair" % (buf[ix].glyph, buf[ix-1].glyph))
return True
# Mark to base is a bit different, as multiple marks can attach to a base
# so we search backwards for the preceding base glyph
# XXX mark to mark
if buf[ix].glyph not in marks:
logging.getLogger("fontFeatures.shaperLib").debug(
" * No, %s is not in our mark list" % (buf[ix].glyph)
)
return False
base_ix = find_base_backwards(self, buf, ix)
if base_ix is None:
logging.getLogger("fontFeatures.shaperLib").debug(
" * No, I couldn't find a base glyph"
)
return False
if buf[base_ix].glyph not in bases:
logging.getLogger("fontFeatures.shaperLib").debug(
" * No, %s is not in our base list" % buf[base_ix].glyph
)
return False
logging.getLogger("fontFeatures.shaperLib").debug(
" * Yes, attaching mark %s/%i to %s/%i"
% (buf[ix].glyph, ix, buf[base_ix].glyph, base_ix)
)
return True
def _do_apply_cursive(self, buf, ix):
this_record = buf[ix]
prev_record = buf[ix - 1]
mark = prev_record.glyph
base = this_record.glyph
if mark not in self.marks or base not in self.bases:
return
exit_x, exit_y = self.marks.get(mark, (0, 0))
entry_x, entry_y = self.bases.get(base, (0, 0))
i = ix - 1
j = ix
if buf.direction == "LTR":
buf[i].position.xAdvance = exit_x + (buf[i].position.xPlacement or 0)
d = entry_x + (buf[j].position.xPlacement or 0)
buf[j].position.xAdvance = (buf[j].position.xAdvance or 0) - d
buf[j].position.xPlacement = (buf[j].position.xPlacement or 0) - d
elif buf.direction == "RTL":
d = exit_x + (buf[i].position.xPlacement or 0)
logging.getLogger("fontFeatures.shaperLib").debug(
"Adjusting advance of %s by %i" % (buf[i].glyph, -d)
)
buf[i].position.xAdvance = (buf[i].position.xAdvance or 0) - d
buf[i].position.xPlacement = (buf[i].position.xPlacement or 0) - d
buf[j].position.xAdvance = entry_x + (buf[j].position.xPlacement or 0)
child = i
parent = j
x_offset = entry_x - exit_x
y_offset = entry_y - exit_y
if not (self.flags & 1):
parent, child = child, parent
x_offset = -x_offset
y_offset = -y_offset
buf[child].position.yPlacement = y_offset
this_record.attach_type = "cursive"
this_record.attach_chain = parent - child
def _do_apply(self, buf, ix, namedclasses={}):
if self.is_cursive:
return _do_apply_cursive(self, buf, ix)
base_ix = find_base_backwards(self, buf, ix)
mark = buf[ix].glyph
base = buf[base_ix].glyph
xpos = self.bases[base][0] - self.marks[mark][0]
ypos = self.bases[base][1] - self.marks[mark][1]
buf[ix].position.xPlacement = xpos
buf[ix].position.yPlacement = ypos
buf[ix].attach_type = "mark"
buf[ix].attach_chain = base_ix - ix
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