Add translate anchors filter

Lib/ufo2ft/filters/__init__.py

@@ -11,6 +11,7 @@
 from .decomposeTransformedComponents import DecomposeTransformedComponentsFilter
 from .explodeColorLayerGlyphs import ExplodeColorLayerGlyphsFilter
 from .flattenComponents import FlattenComponentsFilter
+from .optimizeAnchors import OptimizeAnchorsFilter
 from .propagateAnchors import PropagateAnchorsFilter
 from .removeOverlaps import RemoveOverlapsFilter
 from .sortContours import SortContoursFilter
@@ -23,6 +24,7 @@
     "DecomposeTransformedComponentsFilter",
     "ExplodeColorLayerGlyphsFilter",
     "FlattenComponentsFilter",
+    "OptimizeAnchorsFilter",
     "PropagateAnchorsFilter",
     "RemoveOverlapsFilter",
     "SortContoursFilter",

Lib/ufo2ft/filters/optimizeAnchors.py

@@ -0,0 +1,35 @@
+from ufo2ft.filters.transformations import TransformationsFilter
+from fontTools.misc.transform import Identity, Transform
+import logging
+
+log = logging.getLogger(__name__)
+
+
+class OptimizeAnchorsFilter(TransformationsFilter):
+    def set_context(self, font, glyphSet):
+        # Skip over transformations filter to base filter
+        return super(TransformationsFilter, self).set_context(font, glyphSet)
+
+    def filter(self, glyph):
+        if len(glyph.anchors) == 0 or any(
+            not (a.name.startswith("_")) for a in glyph.anchors
+        ):
+            # We're a base!
+            return False
+
+        # More sanity checks: skip over spacing marks
+        if glyph.width != 0:
+            return False
+        # Also skip over marks which are deliberately positioned over the
+        # previous glyphs
+        if glyph.getBounds().xMax < 0:
+            return False
+
+        # We are a mark glyph with (at least) one attachment point.
+        theanchor = glyph.anchors[0]
+        self.context.matrix = Identity.translate(-theanchor.x, -theanchor.y)
+        log.warn(
+            "Transforming glyph %s to zero anchor %s: %s"
+            % (glyph.name, theanchor.name, self.context.matrix)
+        )
+        return super().filter(glyph)