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https://github.com/python-pillow/Pillow.git
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Merge pull request #818 from dolda2000/itxt
Added support for encoding and decoding iTXt chunks.
This commit is contained in:
Hugo
commit
328fd35dad
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@ -147,6 +147,17 @@ class ChunkStream:
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return cids
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# --------------------------------------------------------------------
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# Subclass of string to allow iTXt chunks to look like strings while
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# keeping their extra information
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class iTXt(str):
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@staticmethod
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def __new__(cls, text, lang, tkey):
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self = str.__new__(cls, text)
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self.lang = lang
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self.tkey = tkey
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return self
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# --------------------------------------------------------------------
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# PNG chunk container (for use with save(pnginfo=))
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@ -159,14 +170,36 @@ class PngInfo:
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def add(self, cid, data):
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self.chunks.append((cid, data))
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def add_itxt(self, key, value, lang="", tkey="", zip=False):
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if not isinstance(key, bytes):
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key = key.encode("latin-1", "strict")
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if not isinstance(value, bytes):
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value = value.encode("utf-8", "strict")
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if not isinstance(lang, bytes):
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lang = lang.encode("utf-8", "strict")
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if not isinstance(tkey, bytes):
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tkey = tkey.encode("utf-8", "strict")
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if zip:
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import zlib
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self.add(b"iTXt", key + b"\0\x01\0" + lang + b"\0" + tkey + b"\0" + zlib.compress(value))
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else:
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self.add(b"iTXt", key + b"\0\0\0" + lang + b"\0" + tkey + b"\0" + value)
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def add_text(self, key, value, zip=0):
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if isinstance(value, iTXt):
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return self.add_itxt(key, value, value.lang, value.tkey, bool(zip))
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# The tEXt chunk stores latin-1 text
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if not isinstance(value, bytes):
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try:
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value = value.encode('latin-1', 'strict')
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except UnicodeError:
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return self.add_itxt(key, value, zip=bool(zip))
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if not isinstance(key, bytes):
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key = key.encode('latin-1', 'strict')
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if not isinstance(value, bytes):
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value = value.encode('latin-1', 'replace')
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if zip:
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import zlib
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self.add(b"zTXt", key + b"\0\0" + zlib.compress(value))
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@ -329,6 +362,43 @@ class PngStream(ChunkStream):
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self.im_info[k] = self.im_text[k] = v
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return s
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def chunk_iTXt(self, pos, length):
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# international text
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r = s = ImageFile._safe_read(self.fp, length)
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try:
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k, r = r.split(b"\0", 1)
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except ValueError:
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return s
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if len(r) < 2:
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return s
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cf, cm, r = i8(r[0]), i8(r[1]), r[2:]
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try:
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lang, tk, v = r.split(b"\0", 2)
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except ValueError:
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return s
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if cf != 0:
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if cm == 0:
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import zlib
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try:
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v = zlib.decompress(v)
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except zlib.error:
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return s
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else:
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return s
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if bytes is not str:
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try:
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k = k.decode("latin-1", "strict")
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lang = lang.decode("utf-8", "strict")
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tk = tk.decode("utf-8", "strict")
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v = v.decode("utf-8", "strict")
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except UnicodeError:
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return s
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self.im_info[k] = self.im_text[k] = iTXt(v, lang, tk)
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return s
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# --------------------------------------------------------------------
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# PNG reader
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@ -129,6 +129,39 @@ class TestFilePng(PillowTestCase):
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HEAD + chunk(b'zTXt', b'spam\0\0' + zlib.compress(b'egg')) + TAIL)
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self.assertEqual(im.info, {'spam': 'egg'})
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def test_bad_itxt(self):
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im = load(HEAD + chunk(b'iTXt') + TAIL)
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self.assertEqual(im.info, {})
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im = load(HEAD + chunk(b'iTXt', b'spam') + TAIL)
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self.assertEqual(im.info, {})
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im = load(HEAD + chunk(b'iTXt', b'spam\0') + TAIL)
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self.assertEqual(im.info, {})
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im = load(HEAD + chunk(b'iTXt', b'spam\0\x02') + TAIL)
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self.assertEqual(im.info, {})
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im = load(HEAD + chunk(b'iTXt', b'spam\0\0\0foo\0') + TAIL)
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self.assertEqual(im.info, {})
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im = load(HEAD + chunk(b'iTXt', b'spam\0\0\0en\0Spam\0egg') + TAIL)
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self.assertEqual(im.info, {"spam": "egg"})
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self.assertEqual(im.info["spam"].lang, "en")
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self.assertEqual(im.info["spam"].tkey, "Spam")
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im = load(HEAD + chunk(b'iTXt', b'spam\0\1\0en\0Spam\0' + zlib.compress(b"egg")[:1]) + TAIL)
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self.assertEqual(im.info, {})
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im = load(HEAD + chunk(b'iTXt', b'spam\0\1\1en\0Spam\0' + zlib.compress(b"egg")) + TAIL)
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self.assertEqual(im.info, {})
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im = load(HEAD + chunk(b'iTXt', b'spam\0\1\0en\0Spam\0' + zlib.compress(b"egg")) + TAIL)
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self.assertEqual(im.info, {"spam": "egg"})
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self.assertEqual(im.info["spam"].lang, "en")
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self.assertEqual(im.info["spam"].tkey, "Spam")
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def test_interlace(self):
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file = "Tests/images/pil123p.png"
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@ -232,6 +265,50 @@ class TestFilePng(PillowTestCase):
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self.assertEqual(im.info, {'TXT': 'VALUE', 'ZIP': 'VALUE'})
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self.assertEqual(im.text, {'TXT': 'VALUE', 'ZIP': 'VALUE'})
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def test_roundtrip_itxt(self):
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# Check iTXt roundtripping
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im = Image.new("RGB", (32, 32))
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info = PngImagePlugin.PngInfo()
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info.add_itxt("spam", "Eggs", "en", "Spam")
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info.add_text("eggs", PngImagePlugin.iTXt("Spam", "en", "Eggs"), zip=True)
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im = roundtrip(im, pnginfo=info)
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self.assertEqual(im.info, {"spam": "Eggs", "eggs": "Spam"})
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self.assertEqual(im.text, {"spam": "Eggs", "eggs": "Spam"})
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self.assertEqual(im.text["spam"].lang, "en")
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self.assertEqual(im.text["spam"].tkey, "Spam")
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self.assertEqual(im.text["eggs"].lang, "en")
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self.assertEqual(im.text["eggs"].tkey, "Eggs")
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def test_nonunicode_text(self):
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# Check so that non-Unicode text is saved as a tEXt rather than iTXt
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im = Image.new("RGB", (32, 32))
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info = PngImagePlugin.PngInfo()
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info.add_text("Text", "Ascii")
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im = roundtrip(im, pnginfo=info)
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self.assertEqual(type(im.info["Text"]), str)
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def test_unicode_text(self):
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# Check preservation of non-ASCII characters on Python3
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# This cannot really be meaningfully tested on Python2,
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# since it didn't preserve charsets to begin with.
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def rt_text(value):
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im = Image.new("RGB", (32, 32))
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info = PngImagePlugin.PngInfo()
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info.add_text("Text", value)
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im = roundtrip(im, pnginfo=info)
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self.assertEqual(im.info, {"Text": value})
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if str is not bytes:
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rt_text(" Aa" + chr(0xa0) + chr(0xc4) + chr(0xff)) # Latin1
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rt_text(chr(0x400) + chr(0x472) + chr(0x4ff)) # Cyrillic
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rt_text(chr(0x4e00) + chr(0x66f0) + # CJK
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chr(0x9fba) + chr(0x3042) + chr(0xac00))
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rt_text("A" + chr(0xc4) + chr(0x472) + chr(0x3042)) # Combined
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def test_scary(self):
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# Check reading of evil PNG file. For information, see:
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# http://scary.beasts.org/security/CESA-2004-001.txt
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