Refactor the Cluster class to be top-level instead of nested the function
This commit is contained in:
Jany Belluz
parent
016aa4cccc
commit
527179619b
@ -1,5 +1,5 @@
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import logging
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import logging
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from collections import defaultdict
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from collections import defaultdict, namedtuple
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from functools import reduce
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from functools import reduce
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from itertools import chain
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from itertools import chain
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from math import log2
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from math import log2
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@ -156,6 +156,143 @@ def _classDef_bytes(
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return min(format1_bytes, format2_bytes)
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return min(format1_bytes, format2_bytes)
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ClusteringContext = namedtuple(
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"ClusteringContext",
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[
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"lines",
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"all_class1",
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"all_class1_data",
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"all_class2_data",
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"valueFormat1_bytes",
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"valueFormat2_bytes",
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],
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)
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class Cluster:
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# TODO(Python 3.7): Turn this into a dataclass
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# ctx: ClusteringContext
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# indices: int
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# Caches
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# TODO(Python 3.8): use functools.cached_property instead of the
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# manually cached properties, and remove the cache fields listed below.
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# _indices: Optional[List[int]] = None
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# _column_indices: Optional[List[int]] = None
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# _cost: Optional[int] = None
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__slots__ = "ctx", "indices_bitmask", "_indices", "_column_indices", "_cost"
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def __init__(self, ctx: ClusteringContext, indices_bitmask: int):
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self.ctx = ctx
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self.indices_bitmask = indices_bitmask
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self._indices = None
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self._column_indices = None
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self._cost = None
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@property
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def indices(self):
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if self._indices is None:
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self._indices = bit_indices(self.indices_bitmask)
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return self._indices
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@property
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def column_indices(self):
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if self._column_indices is None:
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# Indices of columns that have a 1 in at least 1 line
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# => binary OR all the lines
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bitmask = reduce(int.__or__, (self.ctx.lines[i] for i in self.indices))
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self._column_indices = bit_indices(bitmask)
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return self._column_indices
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@property
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def width(self):
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# Add 1 because Class2=0 cannot be used but needs to be encoded.
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return len(self.column_indices) + 1
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@property
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def cost(self):
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if self._cost is None:
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self._cost = (
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# 2 bytes to store the offset to this subtable in the Lookup table above
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2
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# Contents of the subtable
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# From: https://docs.microsoft.com/en-us/typography/opentype/spec/gpos#pair-adjustment-positioning-format-2-class-pair-adjustment
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# uint16 posFormat Format identifier: format = 2
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+ 2
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# Offset16 coverageOffset Offset to Coverage table, from beginning of PairPos subtable.
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+ 2
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+ self.coverage_bytes
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# uint16 valueFormat1 ValueRecord definition — for the first glyph of the pair (may be zero).
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+ 2
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# uint16 valueFormat2 ValueRecord definition — for the second glyph of the pair (may be zero).
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+ 2
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# Offset16 classDef1Offset Offset to ClassDef table, from beginning of PairPos subtable — for the first glyph of the pair.
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+ 2
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+ self.classDef1_bytes
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# Offset16 classDef2Offset Offset to ClassDef table, from beginning of PairPos subtable — for the second glyph of the pair.
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+ 2
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+ self.classDef2_bytes
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# uint16 class1Count Number of classes in classDef1 table — includes Class 0.
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+ 2
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# uint16 class2Count Number of classes in classDef2 table — includes Class 0.
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+ 2
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# Class1Record class1Records[class1Count] Array of Class1 records, ordered by classes in classDef1.
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+ (self.ctx.valueFormat1_bytes + self.ctx.valueFormat2_bytes)
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* len(self.indices)
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* self.width
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)
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return self._cost
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@property
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def coverage_bytes(self):
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format1_bytes = (
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# From https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#coverage-format-1
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# uint16 coverageFormat Format identifier — format = 1
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# uint16 glyphCount Number of glyphs in the glyph array
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4
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# uint16 glyphArray[glyphCount] Array of glyph IDs — in numerical order
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+ sum(len(self.ctx.all_class1[i]) for i in self.indices) * 2
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)
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ranges = sorted(
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chain.from_iterable(self.ctx.all_class1_data[i][0] for i in self.indices)
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)
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merged_range_count = 0
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last = None
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for (start, end) in ranges:
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if last is not None and start != last + 1:
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merged_range_count += 1
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last = end
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format2_bytes = (
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# From https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#coverage-format-2
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# uint16 coverageFormat Format identifier — format = 2
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# uint16 rangeCount Number of RangeRecords
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4
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# RangeRecord rangeRecords[rangeCount] Array of glyph ranges — ordered by startGlyphID.
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# uint16 startGlyphID First glyph ID in the range
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# uint16 endGlyphID Last glyph ID in the range
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# uint16 startCoverageIndex Coverage Index of first glyph ID in range
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+ merged_range_count * 6
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)
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return min(format1_bytes, format2_bytes)
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@property
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def classDef1_bytes(self):
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# We can skip encoding one of the Class1 definitions, and use
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# Class1=0 to represent it instead, because Class1 is gated by the
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# Coverage definition. Use Class1=0 for the highest byte savings.
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# Going through all options takes too long, pick the biggest class
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# = what happens in otlLib.builder.ClassDefBuilder.classes()
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biggest_index = max(self.indices, key=lambda i: len(self.ctx.all_class1[i]))
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return _classDef_bytes(
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self.ctx.all_class1_data, [i for i in self.indices if i != biggest_index]
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)
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@property
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def classDef2_bytes(self):
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# All Class2 need to be encoded because we can't use Class2=0
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return _classDef_bytes(self.ctx.all_class2_data, self.column_indices)
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def cluster_pairs_by_class2_coverage_custom_cost(
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def cluster_pairs_by_class2_coverage_custom_cost(
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font: TTFont,
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font: TTFont,
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pairs: Pairs,
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pairs: Pairs,
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@ -196,134 +333,14 @@ def cluster_pairs_by_class2_coverage_custom_cost(
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valueFormat1_bytes = bit_count(format1) * 2
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valueFormat1_bytes = bit_count(format1) * 2
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valueFormat2_bytes = bit_count(format2) * 2
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valueFormat2_bytes = bit_count(format2) * 2
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# Agglomerative clustering by hand, checking the cost gain of the new
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ctx = ClusteringContext(
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# cluster against the previously separate clusters
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lines,
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# Start with 1 cluster per line
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all_class1,
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# cluster = set of lines = new subtable
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all_class1_data,
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# The class is here so it has a closure over the data above (lines, etc.)
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all_class2_data,
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class Cluster:
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valueFormat1_bytes,
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# TODO(Python 3.7): Turn this into a dataclass
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valueFormat2_bytes,
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# indices: int
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)
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# Caches
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# TODO(Python 3.8): use functools.cached_property instead of the
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# manually cached properties, and remove the cache fields listed below.
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# _indices: Optional[List[int]] = None
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# _column_indices: Optional[List[int]] = None
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# _cost: Optional[int] = None
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__slots__ = "indices_bitmask", "_indices", "_column_indices", "_cost"
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def __init__(self, indices_bitmask: int):
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self.indices_bitmask = indices_bitmask
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self._indices = None
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self._column_indices = None
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self._cost = None
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@property
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def indices(self):
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if self._indices is None:
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self._indices = bit_indices(self.indices_bitmask)
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return self._indices
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@property
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def column_indices(self):
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if self._column_indices is None:
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# Indices of columns that have a 1 in at least 1 line
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# => binary OR all the lines
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bitmask = reduce(int.__or__, (lines[i] for i in self.indices))
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self._column_indices = bit_indices(bitmask)
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return self._column_indices
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@property
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def width(self):
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# Add 1 because Class2=0 cannot be used but needs to be encoded.
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return len(self.column_indices) + 1
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@property
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def cost(self):
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if self._cost is None:
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self._cost = (
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# 2 bytes to store the offset to this subtable in the Lookup table above
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2
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# Contents of the subtable
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# From: https://docs.microsoft.com/en-us/typography/opentype/spec/gpos#pair-adjustment-positioning-format-2-class-pair-adjustment
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# uint16 posFormat Format identifier: format = 2
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+ 2
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# Offset16 coverageOffset Offset to Coverage table, from beginning of PairPos subtable.
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+ 2
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+ self.coverage_bytes
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# uint16 valueFormat1 ValueRecord definition — for the first glyph of the pair (may be zero).
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+ 2
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# uint16 valueFormat2 ValueRecord definition — for the second glyph of the pair (may be zero).
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+ 2
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# Offset16 classDef1Offset Offset to ClassDef table, from beginning of PairPos subtable — for the first glyph of the pair.
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+ 2
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+ self.classDef1_bytes
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# Offset16 classDef2Offset Offset to ClassDef table, from beginning of PairPos subtable — for the second glyph of the pair.
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+ 2
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+ self.classDef2_bytes
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# uint16 class1Count Number of classes in classDef1 table — includes Class 0.
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+ 2
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# uint16 class2Count Number of classes in classDef2 table — includes Class 0.
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+ 2
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# Class1Record class1Records[class1Count] Array of Class1 records, ordered by classes in classDef1.
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+ (valueFormat1_bytes + valueFormat2_bytes)
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* len(self.indices)
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* self.width
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)
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return self._cost
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@property
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def coverage_bytes(self):
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format1_bytes = (
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# From https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#coverage-format-1
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# uint16 coverageFormat Format identifier — format = 1
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# uint16 glyphCount Number of glyphs in the glyph array
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4
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# uint16 glyphArray[glyphCount] Array of glyph IDs — in numerical order
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+ sum(len(all_class1[i]) for i in self.indices) * 2
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)
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ranges = sorted(
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chain.from_iterable(all_class1_data[i][0] for i in self.indices)
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)
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merged_range_count = 0
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last = None
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for (start, end) in ranges:
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if last is not None and start != last + 1:
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merged_range_count += 1
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last = end
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format2_bytes = (
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# From https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#coverage-format-2
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# uint16 coverageFormat Format identifier — format = 2
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# uint16 rangeCount Number of RangeRecords
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4
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# RangeRecord rangeRecords[rangeCount] Array of glyph ranges — ordered by startGlyphID.
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# uint16 startGlyphID First glyph ID in the range
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# uint16 endGlyphID Last glyph ID in the range
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# uint16 startCoverageIndex Coverage Index of first glyph ID in range
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+ merged_range_count * 6
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)
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return min(format1_bytes, format2_bytes)
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@property
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def classDef1_bytes(self):
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# We can skip encoding one of the Class1 definitions, and use
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# Class1=0 to represent it instead, because Class1 is gated by the
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# Coverage definition. Use Class1=0 for the highest byte savings.
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# Going through all options takes too long, pick the biggest class
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# = what happens in otlLib.builder.ClassDefBuilder.classes()
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biggest_index = max(self.indices, key=lambda i: len(all_class1[i]))
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return _classDef_bytes(
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all_class1_data, [i for i in self.indices if i != biggest_index]
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)
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@property
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def classDef2_bytes(self):
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# All Class2 need to be encoded because we can't use Class2=0
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return _classDef_bytes(all_class2_data, self.column_indices)
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def merge(self, other: "Cluster") -> "Cluster":
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return make_cluster(self.indices_bitmask | other.indices_bitmask)
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cluster_cache: Dict[int, Cluster] = {}
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cluster_cache: Dict[int, Cluster] = {}
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@ -331,10 +348,17 @@ def cluster_pairs_by_class2_coverage_custom_cost(
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cluster = cluster_cache.get(indices, None)
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cluster = cluster_cache.get(indices, None)
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if cluster is not None:
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if cluster is not None:
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return cluster
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return cluster
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cluster = Cluster(indices)
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cluster = Cluster(ctx, indices)
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cluster_cache[indices] = cluster
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cluster_cache[indices] = cluster
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return cluster
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return cluster
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def merge(cluster: Cluster, other: Cluster) -> Cluster:
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return make_cluster(cluster.indices_bitmask | other.indices_bitmask)
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# Agglomerative clustering by hand, checking the cost gain of the new
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# cluster against the previously separate clusters
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# Start with 1 cluster per line
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# cluster = set of lines = new subtable
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clusters = [make_cluster(1 << i) for i in range(len(lines))]
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clusters = [make_cluster(1 << i) for i in range(len(lines))]
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# Cost of 1 cluster with everything
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# Cost of 1 cluster with everything
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@ -349,7 +373,7 @@ def cluster_pairs_by_class2_coverage_custom_cost(
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best_merged = None
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best_merged = None
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for i, cluster in enumerate(clusters):
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for i, cluster in enumerate(clusters):
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for j, other in enumerate(clusters[i + 1 :]):
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for j, other in enumerate(clusters[i + 1 :]):
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merged = cluster.merge(other)
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merged = merge(cluster, other)
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cost_change = merged.cost - cluster.cost - other.cost
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cost_change = merged.cost - cluster.cost - other.cost
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if lowest_cost_change is None or cost_change < lowest_cost_change:
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if lowest_cost_change is None or cost_change < lowest_cost_change:
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lowest_cost_change = cost_change
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lowest_cost_change = cost_change
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