Fontforge Python script to decompose nested references into unnested ones

decomposeNestedRefs.py

#!/usr/bin/env fontforge

import fontforge, psMat

def decomposeNestedRefs(font):
	"""Decomposes nested references into simple unnested ones within a font.
	
	Nested references are known to cause problems in certain environments.
	This function recursively decomposes such references into single-level ones."""
	while True:
		nestedRefsFound = False
		for glyph in font.glyphs():
			decomposedRef = []
			decomposedLayers = []
			for ref in glyph.references:
				(srcglyph, matrix, _) = ref
				if len(font[srcglyph].references) > 0:
					fontforge.logWarning("Glyph " + glyph.glyphname + " has a nested reference to " + srcglyph)
					for srcref in font[srcglyph].references:
						decomposedRef += [(srcref[0], psMat.compose(srcref[1], matrix), False)]
						for layer in range(0, font[srcglyph].layer_cnt):
							glyph.layers[layer] += font[srcglyph].layers[layer].dup().transform(matrix)
					nestedRefsFound = True
				else:
					decomposedRef += [ref]
			glyph.references = tuple(decomposedRef)
		if not nestedRefsFound:
			break