[designspace/varLib] Hack to read avar2 mapping and build avar2 table

This just uses list of list of dictionaries. Should use proper objects.

#3049

https://github.com/harfbuzz/boring-expansion-spec/blob/main/avar2-in-designspace.md

Lib/fontTools/designspaceLib/__init__.py

@@ -2005,6 +2005,24 @@ def readAxes(self):
             self.documentObject.axes.append(axisObject)
             self.axisDefaults[axisObject.name] = axisObject.default
 
+        mappingElement = self.root.find(".axes/mapping")
+        self.documentObject.mapping = []
+        if mappingElement is not None:
+            for regionElement in mappingElement.findall("region"):
+                inputElement = regionElement.find("input")
+                outputElement = regionElement.find("output")
+                inputLoc = {}
+                outputLoc = {}
+                for dimElement in inputElement.findall(".dimension"):
+                    tag = dimElement.attrib["tag"]
+                    value = float(dimElement.attrib["xvalue"])
+                    inputLoc[tag] = value
+                for dimElement in outputElement.findall(".dimension"):
+                    tag = dimElement.attrib["tag"]
+                    value = float(dimElement.attrib["xvalue"])
+                    outputLoc[tag] = value
+                self.documentObject.mapping.append([inputLoc, outputLoc])
+
     def readAxisLabel(self, element: ET.Element):
         xml_attrs = {
             "userminimum",
@@ -2547,6 +2565,9 @@ def __init__(self, readerClass=None, writerClass=None):
 
         self.axes: List[Union[AxisDescriptor, DiscreteAxisDescriptor]] = []
         """List of this document's axes."""
+
+        self.mapping = []
+
         self.locationLabels: List[LocationLabelDescriptor] = []
         """List of this document's STAT format 4 labels.
 

Lib/fontTools/designspaceLib/split.py

@@ -345,6 +345,7 @@ def maybeExpandDesignLocation(object):
             )
 
     subDoc.lib = doc.lib
+    subDoc.mapping = doc.mapping  # TODO
 
     return subDoc
 

Lib/fontTools/varLib/__init__.py

@@ -21,6 +21,7 @@
 from typing import List
 from fontTools.misc.vector import Vector
 from fontTools.misc.roundTools import noRound, otRound
+from fontTools.misc.fixedTools import floatToFixed as fl2fi
 from fontTools.misc.textTools import Tag, tostr
 from fontTools.ttLib import TTFont, newTable
 from fontTools.ttLib.tables._f_v_a_r import Axis, NamedInstance
@@ -130,7 +131,7 @@ def _add_fvar(font, axes, instances: List[InstanceDescriptor]):
     return fvar
 
 
-def _add_avar(font, axes):
+def _add_avar(font, axes, mapping, axisTags):
     """
     Add 'avar' table to font.
 
@@ -145,6 +146,7 @@ def _add_avar(font, axes):
     avar = newTable("avar")
 
     interesting = False
+    vals_triples = {}
     for axis in axes.values():
         # Currently, some rasterizers require that the default value maps
         # (-1 to -1, 0 to 0, and 1 to 1) be present for all the segment
@@ -154,6 +156,11 @@ def _add_avar(font, axes):
         # https://github.com/fonttools/fonttools/issues/1011
         # TODO(anthrotype) revert this (and 19c4b37) when issue is fixed
         curve = avar.segments[axis.tag] = {-1.0: -1.0, 0.0: 0.0, 1.0: 1.0}
+
+        keys_triple = (axis.minimum, axis.default, axis.maximum)
+        vals_triple = tuple(axis.map_forward(v) for v in keys_triple)
+        vals_triples[axis.tag] = vals_triple
+
         if not axis.map:
             continue
 
@@ -191,9 +198,6 @@ def _add_avar(font, axes):
                 f"Axis '{axis.name}': mapping output values must be in ascending order."
             )
 
-        keys_triple = (axis.minimum, axis.default, axis.maximum)
-        vals_triple = tuple(axis.map_forward(v) for v in keys_triple)
-
         keys = [models.normalizeValue(v, keys_triple) for v in keys]
         vals = [models.normalizeValue(v, vals_triple) for v in vals]
 
@@ -208,6 +212,44 @@ def _add_avar(font, axes):
         assert +1.0 not in curve or curve[+1.0] == +1.0
         # curve.update({-1.0: -1.0, 0.0: 0.0, 1.0: 1.0})
 
+    if mapping:
+        interesting = True
+
+        derived = [
+            {
+                tag: models.normalizeValue(v, vals_triples[tag])
+                for tag, v in inputLoc.items()
+            }
+            for inputLoc, outputLoc in mapping
+        ]
+        source = [
+            {
+                tag: models.normalizeValue(v, vals_triples[tag])
+                for tag, v in outputLoc.items()
+            }
+            for inputLoc, outputLoc in mapping
+        ]
+
+        model = models.VariationModel(derived, axisTags)
+        builder = varStore.OnlineVarStoreBuilder(axisTags)
+        builder.setModel(model)
+        varIdxes = {
+            t: builder.storeMasters([fl2fi(m.get(t, 0), 14) for m in source])[1]
+            for t in axisTags
+        }
+        store = builder.finish()
+        optimized = store.optimize()
+        varIdxes = {axis: optimized[value] for axis, value in varIdxes.items()}
+
+        varIdxMap = ot.DeltaSetIndexMap()
+        varIdxMap.Format = 1
+        varIdxMap.mapping = [varIdxes[t] for t in axisTags]
+
+        avar.majorVersion = 2
+        avar.table = ot.avar()
+        avar.table.VarIdxMap = varIdxMap
+        avar.table.VarStore = store
+
     assert "avar" not in font
     if not interesting:
         log.info("No need for avar")
@@ -349,7 +391,6 @@ def _remove_TTHinting(font):
 
 
 def _merge_TTHinting(font, masterModel, master_ttfs):
-
     log.info("Merging TT hinting")
     assert "cvar" not in font
 
@@ -452,7 +493,6 @@ def _add_VVAR(font, masterModel, master_ttfs, axisTags):
 
 
 def _add_VHVAR(font, masterModel, master_ttfs, axisTags, tableFields):
-
     tableTag = tableFields.tableTag
     assert tableTag not in font
     log.info("Generating " + tableTag)
@@ -508,7 +548,6 @@ def _get_advance_metrics(
     advMetricses,
     vOrigMetricses=None,
 ):
-
     vhAdvanceDeltasAndSupports = {}
     vOrigDeltasAndSupports = {}
     for glyph in glyphOrder:
@@ -598,7 +637,6 @@ def _get_advance_metrics(
 
 
 def _add_MVAR(font, masterModel, master_ttfs, axisTags):
-
     log.info("Generating MVAR")
 
     store_builder = varStore.OnlineVarStoreBuilder(axisTags)
@@ -677,7 +715,6 @@ def _add_MVAR(font, masterModel, master_ttfs, axisTags):
 
 
 def _add_BASE(font, masterModel, master_ttfs, axisTags):
-
     log.info("Generating BASE")
 
     merger = VariationMerger(masterModel, axisTags, font)
@@ -693,7 +730,6 @@ def _add_BASE(font, masterModel, master_ttfs, axisTags):
 
 
 def _merge_OTL(font, model, master_fonts, axisTags):
-
     log.info("Merging OpenType Layout tables")
     merger = VariationMerger(model, axisTags, font)
 
@@ -734,7 +770,6 @@ def normalize(name, value):
 
     conditional_subs = []
     for rule in rules:
-
         region = []
         for conditions in rule.conditionSets:
             space = {}
@@ -763,6 +798,7 @@ def normalize(name, value):
     "_DesignSpaceData",
     [
         "axes",
+        "mapping",
         "internal_axis_supports",
         "base_idx",
         "normalized_master_locs",
@@ -856,6 +892,9 @@ def load_designspace(designspace):
         axes[axis_name] = axis
     log.info("Axes:\n%s", pformat([axis.asdict() for axis in axes.values()]))
 
+    mapping = ds.mapping
+    log.info("Mapping:\n%s", pformat(mapping))
+
     # Check all master and instance locations are valid and fill in defaults
     for obj in masters + instances:
         obj_name = obj.name or obj.styleName or ""
@@ -915,6 +954,7 @@ def load_designspace(designspace):
 
     return _DesignSpaceData(
         axes,
+        mapping,
         internal_axis_supports,
         base_idx,
         normalized_master_locs,
@@ -1065,8 +1105,6 @@ def build(
     fvar = _add_fvar(vf, ds.axes, ds.instances)
     if "STAT" not in exclude:
         _add_stat(vf)
-    if "avar" not in exclude:
-        _add_avar(vf, ds.axes)
 
     # Map from axis names to axis tags...
     normalized_master_locs = [
@@ -1080,6 +1118,8 @@ def build(
     assert 0 == model.mapping[ds.base_idx]
 
     log.info("Building variations tables")
+    if "avar" not in exclude:
+        _add_avar(vf, ds.axes, ds.mapping, axisTags)
     if "BASE" not in exclude and "BASE" in vf:
         _add_BASE(vf, model, master_fonts, axisTags)
     if "MVAR" not in exclude: