def __init__(self, font, decompositions):
self.font = font
self.decompositions = decompositions
self.missing_chars = Tally("Missing combinable characters", "char")
self.unknown_classes = Tally("Unknown combining classes")
class FontFiller(object):
"""
Utility class for filling out a font based on combining characters.
"""
def __init__(self, font, decompositions):
self.font = font
self.decompositions = decompositions
self.missing_chars = Tally("Missing combinable characters", "char")
self.unknown_classes = Tally("Unknown combining classes")
def add_glyph_to_font(self, char):
"""
Add the glyph representing char to the given font, if it can be built.
"""
if ord(char) in self.font:
# It's already there!
return True
if char not in self.decompositions:
# We don't know how to build it.
return False
components = self.decompositions[char]
for component_char, combining_class in components:
if combining_class not in SUPPORTED_COMBINING_CLASSES:
# We don't know how to combine this with other characters.
self.unknown_classes.record(combining_class)
return False
if not self.add_glyph_to_font(component_char):
# We don't know how to build one of the required components.
self.missing_chars.record(component_char)
return False
# Now we have all the components, let's put them together!
glyph = self.font.new_glyph_from_data("char%d" % ord(char),
codepoint=ord(char))
# Draw on the base char.
base_char = components[0][0]
base_combining_class = components[0][1]
assert (base_combining_class == CC_SPACING,
"base char should be a spacing char")
base_glyph = self.font[ord(base_char)]
glyph.merge_glyph(base_glyph, 0,0)
glyph.advance = base_glyph.advance
for component_char, combining_class in components[1:]:
other_glyph = self.font[ord(component_char)]
if combining_class == CC_SPACING:
# Draw other_glyph beside the current glyph
glyph.merge_glyph(other_glyph, glyph.advance,0)
glyph.advance += other_glyph.advance
elif combining_class == CC_A:
# Draw other_glyph centred above the current glyph
y_offset = 0
x_offset = 0
if "CAP_HEIGHT" in self.font and glyph.bbH > 0:
# We assume combining glyphs are drawn above the
# CAP_HEIGHT.
y_offset = glyph.get_ascent() - self.font["CAP_HEIGHT"]
if glyph.bbW > 0:
x_offset = int(
float(glyph.advance)/2
- float(other_glyph.advance)/2
)
glyph.merge_glyph(other_glyph, x_offset,y_offset)
elif combining_class in (CC_B, CC_B_ATTACHED):
# Draw other_glyph centred below the current glyph
y_offset = -glyph.get_descent()
x_offset = 0
if glyph.bbW > 0:
x_offset = int(
float(glyph.advance)/2
- float(other_glyph.advance)/2
)
glyph.merge_glyph(other_glyph, x_offset,y_offset)
else:
raise RuntimeError("Unsupported combining class %d" %
(combining_class,))
return True
def add_decomposable_glyphs_to_font(self):
"""
Adds all the glyphs that can be built to the given font.
"""
for char in self.decompositions:
self.add_glyph_to_font(char)