Library import 6 (#888)

1 files changed, 54 insertions, 0 deletions

diff --git a/contrib/python/fonttools/fontTools/ttLib/ttGlyphSet.py b/contrib/python/fonttools/fontTools/ttLib/ttGlyphSet.py
index 349cc2c73f..5d188d6a10 100644
--- a/contrib/python/fonttools/fontTools/ttLib/ttGlyphSet.py
+++ b/contrib/python/fonttools/fontTools/ttLib/ttGlyphSet.py
@@ -9,6 +9,11 @@ from fontTools.misc.fixedTools import otRound
 from fontTools.misc.loggingTools import deprecateFunction
 from fontTools.misc.transform import Transform
 from fontTools.pens.transformPen import TransformPen, TransformPointPen
+from fontTools.pens.recordingPen import (
+    DecomposingRecordingPen,
+    lerpRecordings,
+    replayRecording,
+)
 
 
 class _TTGlyphSet(Mapping):
@@ -321,3 +326,52 @@ def _setCoordinates(glyph, coord, glyfTable, *, recalcBounds=True):
         verticalAdvanceWidth,
         topSideBearing,
     )
+
+
+class LerpGlyphSet(Mapping):
+    """A glyphset that interpolates between two other glyphsets.
+
+    Factor is typically between 0 and 1. 0 means the first glyphset,
+    1 means the second glyphset, and 0.5 means the average of the
+    two glyphsets. Other values are possible, and can be useful to
+    extrapolate. Defaults to 0.5.
+    """
+
+    def __init__(self, glyphset1, glyphset2, factor=0.5):
+        self.glyphset1 = glyphset1
+        self.glyphset2 = glyphset2
+        self.factor = factor
+
+    def __getitem__(self, glyphname):
+        if glyphname in self.glyphset1 and glyphname in self.glyphset2:
+            return LerpGlyph(glyphname, self)
+        raise KeyError(glyphname)
+
+    def __contains__(self, glyphname):
+        return glyphname in self.glyphset1 and glyphname in self.glyphset2
+
+    def __iter__(self):
+        set1 = set(self.glyphset1)
+        set2 = set(self.glyphset2)
+        return iter(set1.intersection(set2))
+
+    def __len__(self):
+        set1 = set(self.glyphset1)
+        set2 = set(self.glyphset2)
+        return len(set1.intersection(set2))
+
+
+class LerpGlyph:
+    def __init__(self, glyphname, glyphset):
+        self.glyphset = glyphset
+        self.glyphname = glyphname
+
+    def draw(self, pen):
+        recording1 = DecomposingRecordingPen(self.glyphset.glyphset1)
+        self.glyphset.glyphset1[self.glyphname].draw(recording1)
+        recording2 = DecomposingRecordingPen(self.glyphset.glyphset2)
+        self.glyphset.glyphset2[self.glyphname].draw(recording2)
+
+        factor = self.glyphset.factor
+
+        replayRecording(lerpRecordings(recording1.value, recording2.value, factor), pen)