factor out remove_overlaps routine, add typing annotations

Snippets/remove-overlaps.py

@@ -5,7 +5,9 @@
 
 
 import sys
-from fontTools.ttLib import TTFont
+from typing import Iterable, Optional, Mapping
+from fontTools.ttLib import ttFont
+from fontTools.ttLib.tables import _g_l_y_f
 from fontTools.pens.recordingPen import DecomposingRecordingPen
 from fontTools.pens.ttGlyphPen import TTGlyphPen
 
@@ -17,15 +19,19 @@ except ImportError:
         "`pip install skia-pathops` and then retry."
     )
 
+_TTGlyphMapping = Mapping[str, ttFont._TTGlyph]
 
-def skpath_from_simple_glyph(glyphName, glyphSet):
+
+def skpath_from_simple_glyph(glyphName: str, glyphSet: _TTGlyphMapping) -> pathops.Path:
     path = pathops.Path()
     pathPen = path.getPen()
     glyphSet[glyphName].draw(pathPen)
     return path
 
 
-def skpath_from_composite_glyph(glyphName, glyphSet):
+def skpath_from_composite_glyph(
+    glyphName: str, glyphSet: _TTGlyphMapping
+) -> pathops.Path:
     # record TTGlyph outlines without components
     dcPen = DecomposingRecordingPen(glyphSet)
     glyphSet[glyphName].draw(dcPen)
@@ -36,7 +42,7 @@ def skpath_from_composite_glyph(glyphName, glyphSet):
     return path
 
 
-def simple_glyph_from_skpath(path):
+def simple_glyph_from_skpath(path: pathops.Path) -> _g_l_y_f.Glyph:
     # Skia paths have no 'components', no need for glyphSet
     ttPen = TTGlyphPen(glyphSet=None)
     path.draw(ttPen)
@@ -47,39 +53,48 @@ def simple_glyph_from_skpath(path):
     return glyph
 
 
-def main():
-    if len(sys.argv) != 3:
-        print("usage: remove-overlaps.py fontfile.ttf outfile.ttf")
+def remove_overlaps(
+    font: ttFont.TTFont, glyphNames: Optional[Iterable[str]] = None
+) -> None:
+    if glyphNames is None:
+        glyphNames = font.getGlyphOrder()
+
+    glyfTable = font["glyf"]
+    hmtxTable = font["hmtx"]
+    glyphSet = font.getGlyphSet()
+
+    for glyphName in glyphNames:
+        if glyfTable[glyphName].isComposite():
+            path = skpath_from_composite_glyph(glyphName, glyphSet)
+        else:
+            path = skpath_from_simple_glyph(glyphName, glyphSet)
+
+        # duplicate path
+        path2 = pathops.Path(path)
+
+        # remove overlaps
+        path2.simplify()
+
+        # replace TTGlyph if simplified copy is different
+        if path2 != path:
+            glyfTable[glyphName] = glyph = simple_glyph_from_skpath(path2)
+            # also ensure hmtx LSB == glyph.xMin so glyph origin is at x=0
+            width, lsb = hmtxTable[glyphName]
+            if lsb != glyph.xMin:
+                hmtxTable[glyphName] = (width, glyph.xMin)
+
+
+def main() -> None:
+    if len(sys.argv) < 3:
+        print("usage: remove-overlaps.py fontfile.ttf outfile.ttf [GLYPHNAMES ...]")
         sys.exit(1)
 
     src = sys.argv[1]
     dst = sys.argv[2]
+    glyphNames = sys.argv[3:] or None
 
-    with TTFont(src) as f:
-        glyfTable = f["glyf"]
-        hmtxTable = f["hmtx"]
-        glyphSet = f.getGlyphSet()
-
-        for glyphName in glyphSet.keys():
-            if glyfTable[glyphName].isComposite():
-                path = skpath_from_composite_glyph(glyphName, glyphSet)
-            else:
-                path = skpath_from_simple_glyph(glyphName, glyphSet)
-
-            # duplicate path
-            path2 = pathops.Path(path)
-
-            # remove overlaps
-            path2.simplify()
-
-            # replace TTGlyph if simplified copy is different
-            if path2 != path:
-                glyfTable[glyphName] = glyph = simple_glyph_from_skpath(path2)
-                # also ensure hmtx LSB == glyph.xMin so glyph origin is at x=0
-                width, lsb = hmtxTable[glyphName]
-                if lsb != glyph.xMin:
-                    hmtxTable[glyphName] = (width, glyph.xMin)
-
+    with ttFont.TTFont(src) as f:
+        remove_overlaps(f, glyphNames)
         f.save(dst)