def glyphs_modified(font_before, font_after):
"""For glyphs which are shared between the two fonts, return glyphs
who's surface areas differ and the diff is greater than a
predetermined threshold"""
bad_glyphs = []
glyphs_before = font_before.getGlyphSet()
glyphs_after = font_after.getGlyphSet()
glyphs_shared = set(glyphs_before.keys()) & set(glyphs_after.keys())
upm_before = font_before['head'].unitsPerEm
upm_after = font_after['head'].unitsPerEm
pen_before = AreaPen(glyphs_before)
pen_after = AreaPen(glyphs_after)
for glyph in glyphs_shared:
glyphs_before[glyph].draw(pen_before)
glyphs_after[glyph].draw(pen_after)
area_before = pen_before.value
pen_before.value = 0
area_after = pen_after.value
pen_after.value = 0
area_norm_before = (area_before / upm_before) * upm_after
area_norm_after = (area_after / upm_after) * upm_before
if area_norm_before != area_norm_after:
if abs(area_norm_before - area_norm_after) > GLYPH_AREA_THRESHOLD:
bad_glyphs.append(glyph)
glyphs_encoded = font_before['cmap'].getcmap(3, 1).cmap
return [i for i in glyphs_encoded.items() if i[1] in bad_glyphs]
def glyphs_surface_area(font):
"""Calculate the surface area of a glyph's ink"""
glyphs = {}
glyph_set = font.getGlyphSet()
area_pen = AreaPen(glyph_set)
for glyph in glyph_set.keys():
glyph_set[glyph].draw(area_pen)
area = area_pen.value
area_pen.value = 0
glyphs[glyph] = area
return glyphs