def test_chunk_order(self):
im = Image.open("Tests/images/icc_profile.png")
test_file = self.tempfile("temp.png")
im.convert("P").save(test_file, dpi=(100, 100))
chunks = []
with open(test_file, "rb") as fp:
fp.read(8)
with PngImagePlugin.PngStream(fp) as png:
while True:
cid, pos, length = png.read()
chunks.append(cid)
try:
s = png.call(cid, pos, length)
except EOFError:
break
png.crc(cid, s)
# https://www.w3.org/TR/PNG/#5ChunkOrdering
# IHDR - shall be first
self.assertEqual(chunks.index(b"IHDR"), 0)
# PLTE - before first IDAT
self.assertLess(chunks.index(b"PLTE"), chunks.index(b"IDAT"))
# iCCP - before PLTE and IDAT
self.assertLess(chunks.index(b"iCCP"), chunks.index(b"PLTE"))
self.assertLess(chunks.index(b"iCCP"), chunks.index(b"IDAT"))
# tRNS - after PLTE, before IDAT
self.assertGreater(chunks.index(b"tRNS"), chunks.index(b"PLTE"))
self.assertLess(chunks.index(b"tRNS"), chunks.index(b"IDAT"))
# pHYs - before IDAT
self.assertLess(chunks.index(b"pHYs"), chunks.index(b"IDAT"))
def test_truncated_chunks(self, cid):
fp = BytesIO()
with PngImagePlugin.PngStream(fp) as png:
with pytest.raises(ValueError):
png.call(cid, 0, 0)
ImageFile.LOAD_TRUNCATED_IMAGES = True
png.call(cid, 0, 0)
ImageFile.LOAD_TRUNCATED_IMAGES = False
def get_chunks(self, filename):
chunks = []
with open(filename, "rb") as fp:
fp.read(8)
with PngImagePlugin.PngStream(fp) as png:
while True:
cid, pos, length = png.read()
chunks.append(cid)
try:
s = png.call(cid, pos, length)
except EOFError:
break
png.crc(cid, s)
return chunks
