added a script to convert COLRv1 to SVGs

Useful for debugging and testing.

tools/colr2svg.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+"""Convert COLRv1 font to a set of SVG files, one per base color glyph."""
+import os
+import sys
+
+# extend PYTHONPATH to include ../tests dir where colr_to_svg module is located
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.dirname(__file__)), "tests"))
+
+from colr_to_svg import colr_to_svg
+from fontTools.ttLib import TTFont
+from picosvg.geometric_types import Rect
+from lxml import etree
+
+
+VIEW_BOX_SIZE = 128
+
+try:
+    fontfile, destdir = sys.argv[1:]
+except ValueError:
+    sys.exit("usage: ./colr2svg.py FONTFILE SVG_OUTPUT_DIR")
+
+font = TTFont(fontfile)
+viewbox = Rect(0, 0, VIEW_BOX_SIZE, VIEW_BOX_SIZE)
+
+os.makedirs(destdir, exist_ok=True)
+
+for glyph_name, svg in colr_to_svg(viewbox, font).items():
+    output_file = os.path.join(destdir, f"{glyph_name}.svg")
+    with open(output_file, "wb") as f:
+        f.write(etree.tostring(svg.svg_root, pretty_print=True))
+    print(f"{output_file}")