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[varLib.builder] Implement building 32bit VarStore

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The full optimizer in varLib.varStore still needs to be updated.
But this pretty much enables building 32bit VarStores, even if they
won't be fully optimal.

Part of https://github.com/fonttools/fonttools/issues/2279
This commit is contained in:
Behdad Esfahbod 2021-05-01 14:27:11 -06:00
parent 802e3636bc
commit e454e96238
1 changed files with 25 additions and 24 deletions
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49
Lib/fontTools/varLib/builder.py
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@ -26,39 +26,40 @@ def buildVarRegionList(supports, axisTags):
return self
def _reorderItem(lst, narrows, zeroes):
out = []
count = len(lst)
for i in range(count):
if i not in narrows:
out.append(lst[i])
for i in range(count):
if i in narrows and i not in zeroes:
out.append(lst[i])
return out
def _reorderItem(lst, mapping):
return [lst[i] for i in mapping]
def VarData_calculateNumShorts(self, optimize=False):
count = self.VarRegionCount
items = self.Item
narrows = set(range(count))
zeroes = set(range(count))
bit_lengths = [0] * count
for item in items:
wides = [i for i in narrows if not (-128 <= item[i] <= 127)]
narrows.difference_update(wides)
nonzeroes = [i for i in zeroes if item[i]]
zeroes.difference_update(nonzeroes)
if not narrows and not zeroes:
break
bl = [(i + (i < -1)).bit_length() for i in item]
bit_lengths = [max(*pair) for pair in zip(bl, bit_lengths)]
byte_lengths = [((b + 8) // 8) if b else 0 for b in bit_lengths]
# https://github.com/fonttools/fonttools/issues/2279
longWords = any(b > 2 for b in byte_lengths)
if optimize:
# Reorder columns such that all SHORT columns come before UINT8
self.VarRegionIndex = _reorderItem(self.VarRegionIndex, narrows, zeroes)
# Reorder columns such that wider columns come before narrower columns
mapping = []
mapping.extend(i for i,b in enumerate(byte_lengths) if b > 2)
mapping.extend(i for i,b in enumerate(byte_lengths) if b == 2)
mapping.extend(i for i,b in enumerate(byte_lengths) if b == 1)
byte_lengths = _reorderItem(byte_lengths, mapping)
self.VarRegionIndex = _reorderItem(self.VarRegionIndex, mapping)
self.VarRegionCount = len(self.VarRegionIndex)
for i in range(len(items)):
items[i] = _reorderItem(items[i], narrows, zeroes)
self.NumShorts = count - len(narrows)
items[i] = _reorderItem(items[i], mapping)
if longWords:
self.NumShorts = max((i for i,b in enumerate(byte_lengths) if b > 2), default=-1) + 1
self.NumShorts |= 0x8000
else:
wides = set(range(count)) - narrows
self.NumShorts = 1+max(wides) if wides else 0
self.NumShorts = max((i for i,b in enumerate(byte_lengths) if b > 1), default=-1) + 1
self.VarRegionCount = len(self.VarRegionIndex)
return self