Flat Kerning Representation ↩
This example shows how to register a defcon.Kerning representation that outputs the flat kerning of a font. Considered that kerning depends on defcon.Groups too, the script registers a subscriber to make sure the representation cache is invalidated if a kerning group is edited.
from time import time
from defcon import Kerning, registerRepresentationFactory
from mojo.subscriber import Subscriber, registerCurrentFontSubscriber
FIRST_PREFIX = "public.kern1."
SECOND_PREFIX = "public.kern2."
class KerningGroupsWatcher(Subscriber):
debug = True
fontGroupsDidChangeDelay = 0
def fontGroupsDidChange(self, info):
info["font"].kerning.changed()
print("an edit to groups invalidates the kerning cache!")
def flatKerningFactory(kerning):
print("compute flat kerning!")
flatK = {}
font = kerning.font
for pair, correction in kerning.items():
first, second = pair
# both groups
if first.startswith(FIRST_PREFIX) and second.startswith(SECOND_PREFIX):
for firstGlyph in font.groups[first]:
for secondGlyph in font.groups[second]:
flatK[(firstGlyph, secondGlyph)] = correction
# first group, second glyph
elif first.startswith(FIRST_PREFIX):
for firstGlyph in font.groups[first]:
flatK[(firstGlyph, second)] = correction
# first glyph, second group
elif second.startswith(SECOND_PREFIX):
for secondGlyph in font.groups[second]:
flatK[(first, secondGlyph)] = correction
# first glyph, second glyph
else:
flatK[(first, second)] = correction
return flatK
if __name__ == "__main__":
registerCurrentFontSubscriber(KerningGroupsWatcher)
registerRepresentationFactory(Kerning, "flatKerningRepresentation", flatKerningFactory)
font = CurrentFont()
# first computation
start = time()
flatKerning = font.kerning.getRepresentation("flatKerningRepresentation")
end = time()
print(end - start)
print(len(flatKerning))
# retrieve the cache
start = time()
end = time()
print(end - start)
print(len(flatKerning))
# edit the groups
font.groups[f"{FIRST_PREFIX}.someGroup"] = ["A", "B", "C"]
# compute again
start = time()
flatKerning = font.kerning.getRepresentation("flatKerningRepresentation")
end = time()
print(end - start)
print(len(flatKerning))
# remove the pseudo group
del font.groups[f"{FIRST_PREFIX}.someGroup"]