Merge pull request #1848 from googlefonts/cu2qu-filter

Add convert-to-quadratics filter + test

src/fontra/workflow/actions/glyph.py

@@ -5,8 +5,10 @@
 from dataclasses import dataclass, replace
 from typing import Any
 
+from fontTools.cu2qu.ufo import glyphs_to_quadratic
 from fontTools.misc.roundTools import otRound
 from fontTools.misc.transform import Transform
+from fontTools.pens.pointPen import SegmentToPointPen
 
 from ...core.classes import (
     Component,
@@ -17,7 +19,7 @@
     StaticGlyph,
     VariableGlyph,
 )
-from ...core.path import PackedPath
+from ...core.path import PackedPath, PackedPathPointPen
 from ...core.varutils import locationToTuple
 from .base import (
     BaseFilter,
@@ -533,3 +535,56 @@ async def processGlyph(self, glyph: VariableGlyph) -> VariableGlyph:
                 },
             )
         return glyph
+
+
+@dataclass(kw_only=True)
+class Cu2QuGlyphGlue:
+    path: PackedPath
+
+    def __post_init__(self):
+        self._pen = None
+
+    def clearContours(self):
+        pass
+
+    def drawPoints(self, pen):
+        self.path.drawPoints(pen)
+
+    def getPen(self):
+        self._pen = PackedPathPointPen()
+        return SegmentToPointPen(self._pen)
+
+    @property
+    def modifiedPath(self):
+        return self._pen.getPath() if self._pen is not None else self.path
+
+
+@registerFilterAction("convert-to-quadratics")
+@dataclass(kw_only=True)
+class ConvertToQuadratics(BaseFilter):
+    maximumError: float | None = None
+    reverseDirection: bool = False
+
+    async def processGlyph(self, glyph):
+        # TODO: we should split by discrete subspace so we can support discrete axes
+        layers = {
+            source.layerName: glyph.layers[source.layerName]
+            for source in getActiveSources(glyph.sources)
+        }
+        wrappedPaths = [
+            Cu2QuGlyphGlue(path=layer.glyph.path) for layer in layers.values()
+        ]
+        if glyphs_to_quadratic(
+            wrappedPaths,
+            max_err=self.maximumError,
+            reverse_direction=self.reverseDirection,
+        ):
+            newLayers = dict(glyph.layers)
+            for (layerName, layer), wrappedPath in zip(layers.items(), wrappedPaths):
+                newLayers[layerName] = replace(
+                    layer, glyph=replace(layer.glyph, path=wrappedPath.modifiedPath)
+                )
+
+            glyph = replace(glyph, layers=newLayers)
+
+        return glyph

test-py/data/workflow/output-convert-to-quadratics.fontra/font-data.json

@@ -0,0 +1,194 @@
+{
+"axes": {
+"axes": [
+{
+"name": "width",
+"label": "width",
+"tag": "wdth",
+"minValue": 0,
+"defaultValue": 0,
+"maxValue": 1000
+},
+{
+"name": "weight",
+"label": "weight",
+"tag": "wght",
+"minValue": 100,
+"defaultValue": 100,
+"maxValue": 900,
+"mapping": [
+[
+100,
+150
+],
+[
+900,
+850
+]
+]
+},
+{
+"name": "italic",
+"label": "italic",
+"tag": "ital",
+"values": [
+0,
+1
+],
+"defaultValue": 0
+}
+]
+},
+"sources": {
+"3aa9223b": {
+"name": "Support",
+"location": {
+"italic": 0,
+"weight": 595,
+"width": 0
+},
+"lineMetricsHorizontalLayout": {
+"ascender": {
+"value": 800,
+"zone": 16
+},
+"capHeight": {
+"value": 750,
+"zone": 16
+},
+"xHeight": {
+"value": 500,
+"zone": 16
+},
+"baseline": {
+"value": 0,
+"zone": -16
+},
+"descender": {
+"value": -250,
+"zone": -16
+}
+}
+},
+"5bea6334": {
+"name": "LightCondensed",
+"location": {
+"italic": 0,
+"weight": 150,
+"width": 0
+},
+"lineMetricsHorizontalLayout": {
+"ascender": {
+"value": 800,
+"zone": 16
+},
+"capHeight": {
+"value": 750,
+"zone": 16
+},
+"xHeight": {
+"value": 500,
+"zone": 16
+},
+"baseline": {
+"value": 0,
+"zone": -16
+},
+"descender": {
+"value": -250,
+"zone": -16
+}
+}
+},
+"5d4e7f1d": {
+"name": "BoldWide",
+"location": {
+"italic": 0,
+"weight": 850,
+"width": 1000
+},
+"lineMetricsHorizontalLayout": {
+"ascender": {
+"value": 800,
+"zone": 16
+},
+"capHeight": {
+"value": 750,
+"zone": 16
+},
+"xHeight": {
+"value": 500,
+"zone": 16
+},
+"baseline": {
+"value": 0,
+"zone": -16
+},
+"descender": {
+"value": -250,
+"zone": -16
+}
+}
+},
+"d7abd222": {
+"name": "LightWide",
+"location": {
+"italic": 0,
+"weight": 150,
+"width": 1000
+},
+"lineMetricsHorizontalLayout": {
+"ascender": {
+"value": 800,
+"zone": 16
+},
+"capHeight": {
+"value": 750,
+"zone": 16
+},
+"xHeight": {
+"value": 500,
+"zone": 16
+},
+"baseline": {
+"value": 0,
+"zone": -16
+},
+"descender": {
+"value": -250,
+"zone": -16
+}
+}
+},
+"f22d1bbd": {
+"name": "BoldCondensed",
+"location": {
+"italic": 0,
+"weight": 850,
+"width": 0
+},
+"lineMetricsHorizontalLayout": {
+"ascender": {
+"value": 800,
+"zone": 16
+},
+"capHeight": {
+"value": 750,
+"zone": 16
+},
+"xHeight": {
+"value": 500,
+"zone": 16
+},
+"baseline": {
+"value": 0,
+"zone": -16
+},
+"descender": {
+"value": -250,
+"zone": -16
+}
+}
+}
+}
+}

test-py/data/workflow/output-convert-to-quadratics.fontra/glyph-info.csv

@@ -0,0 +1,3 @@
+glyph name;code points
+A;U+0041,U+0061
+B;U+0042,U+0062