aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/python/fonttools/fontTools/varLib/instancer/featureVars.py
blob: d9370d9d653aa847a0ada1fae2c3869b66fa27af (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
from fontTools.ttLib.tables import otTables as ot
from copy import deepcopy
import logging


log = logging.getLogger("fontTools.varLib.instancer")


def _featureVariationRecordIsUnique(rec, seen):
    conditionSet = []
    conditionSets = (
        rec.ConditionSet.ConditionTable if rec.ConditionSet is not None else []
    )
    for cond in conditionSets:
        if cond.Format != 1:
            # can't tell whether this is duplicate, assume is unique
            return True
        conditionSet.append(
            (cond.AxisIndex, cond.FilterRangeMinValue, cond.FilterRangeMaxValue)
        )
    # besides the set of conditions, we also include the FeatureTableSubstitution
    # version to identify unique FeatureVariationRecords, even though only one
    # version is currently defined. It's theoretically possible that multiple
    # records with same conditions but different substitution table version be
    # present in the same font for backward compatibility.
    recordKey = frozenset([rec.FeatureTableSubstitution.Version] + conditionSet)
    if recordKey in seen:
        return False
    else:
        seen.add(recordKey)  # side effect
        return True


def _limitFeatureVariationConditionRange(condition, axisLimit):
    minValue = condition.FilterRangeMinValue
    maxValue = condition.FilterRangeMaxValue

    if (
        minValue > maxValue
        or minValue > axisLimit.maximum
        or maxValue < axisLimit.minimum
    ):
        # condition invalid or out of range
        return

    return tuple(
        axisLimit.renormalizeValue(v, extrapolate=False) for v in (minValue, maxValue)
    )


def _instantiateFeatureVariationRecord(
    record, recIdx, axisLimits, fvarAxes, axisIndexMap
):
    applies = True
    shouldKeep = False
    newConditions = []
    from fontTools.varLib.instancer import NormalizedAxisTripleAndDistances

    default_triple = NormalizedAxisTripleAndDistances(-1, 0, +1)
    if record.ConditionSet is None:
        record.ConditionSet = ot.ConditionSet()
        record.ConditionSet.ConditionTable = []
        record.ConditionSet.ConditionCount = 0
    for i, condition in enumerate(record.ConditionSet.ConditionTable):
        if condition.Format == 1:
            axisIdx = condition.AxisIndex
            axisTag = fvarAxes[axisIdx].axisTag

            minValue = condition.FilterRangeMinValue
            maxValue = condition.FilterRangeMaxValue
            triple = axisLimits.get(axisTag, default_triple)

            if not (minValue <= triple.default <= maxValue):
                applies = False

            # if condition not met, remove entire record
            if triple.minimum > maxValue or triple.maximum < minValue:
                newConditions = None
                break

            if axisTag in axisIndexMap:
                # remap axis index
                condition.AxisIndex = axisIndexMap[axisTag]

                # remap condition limits
                newRange = _limitFeatureVariationConditionRange(condition, triple)
                if newRange:
                    # keep condition with updated limits
                    minimum, maximum = newRange
                    condition.FilterRangeMinValue = minimum
                    condition.FilterRangeMaxValue = maximum
                    shouldKeep = True
                    if minimum != -1 or maximum != +1:
                        newConditions.append(condition)
                else:
                    # condition out of range, remove entire record
                    newConditions = None
                    break

        else:
            log.warning(
                "Condition table {0} of FeatureVariationRecord {1} has "
                "unsupported format ({2}); ignored".format(i, recIdx, condition.Format)
            )
            applies = False
            newConditions.append(condition)

    if newConditions is not None and shouldKeep:
        record.ConditionSet.ConditionTable = newConditions
        if not newConditions:
            record.ConditionSet = None
        shouldKeep = True
    else:
        shouldKeep = False

    # Does this *always* apply?
    universal = shouldKeep and not newConditions

    return applies, shouldKeep, universal


def _instantiateFeatureVariations(table, fvarAxes, axisLimits):
    pinnedAxes = set(axisLimits.pinnedLocation())
    axisOrder = [axis.axisTag for axis in fvarAxes if axis.axisTag not in pinnedAxes]
    axisIndexMap = {axisTag: axisOrder.index(axisTag) for axisTag in axisOrder}

    featureVariationApplied = False
    uniqueRecords = set()
    newRecords = []
    defaultsSubsts = None

    for i, record in enumerate(table.FeatureVariations.FeatureVariationRecord):
        applies, shouldKeep, universal = _instantiateFeatureVariationRecord(
            record, i, axisLimits, fvarAxes, axisIndexMap
        )

        if shouldKeep and _featureVariationRecordIsUnique(record, uniqueRecords):
            newRecords.append(record)

        if applies and not featureVariationApplied:
            assert record.FeatureTableSubstitution.Version == 0x00010000
            defaultsSubsts = deepcopy(record.FeatureTableSubstitution)
            for default, rec in zip(
                defaultsSubsts.SubstitutionRecord,
                record.FeatureTableSubstitution.SubstitutionRecord,
            ):
                default.Feature = deepcopy(
                    table.FeatureList.FeatureRecord[rec.FeatureIndex].Feature
                )
                table.FeatureList.FeatureRecord[rec.FeatureIndex].Feature = deepcopy(
                    rec.Feature
                )
            # Set variations only once
            featureVariationApplied = True

        # Further records don't have a chance to apply after a universal record
        if universal:
            break

    # Insert a catch-all record to reinstate the old features if necessary
    if featureVariationApplied and newRecords and not universal:
        defaultRecord = ot.FeatureVariationRecord()
        defaultRecord.ConditionSet = ot.ConditionSet()
        defaultRecord.ConditionSet.ConditionTable = []
        defaultRecord.ConditionSet.ConditionCount = 0
        defaultRecord.FeatureTableSubstitution = defaultsSubsts

        newRecords.append(defaultRecord)

    if newRecords:
        table.FeatureVariations.FeatureVariationRecord = newRecords
        table.FeatureVariations.FeatureVariationCount = len(newRecords)
    else:
        del table.FeatureVariations
        # downgrade table version if there are no FeatureVariations left
        table.Version = 0x00010000


def instantiateFeatureVariations(varfont, axisLimits):
    for tableTag in ("GPOS", "GSUB"):
        if tableTag not in varfont or not getattr(
            varfont[tableTag].table, "FeatureVariations", None
        ):
            continue
        log.info("Instantiating FeatureVariations of %s table", tableTag)
        _instantiateFeatureVariations(
            varfont[tableTag].table, varfont["fvar"].axes, axisLimits
        )
        # remove unreferenced lookups
        varfont[tableTag].prune_lookups()