def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("b", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
python类_safe_read()的实例源码
def chunk_tRNS(self, pos, length):
# transparency
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
if _simple_palette.match(s):
i = s.find(b"\0")
if i >= 0:
self.im_info["transparency"] = i
elif _null_palette.match(s):
self.im_info["transparency"] = 0
else:
self.im_info["transparency"] = s
elif self.im_mode == "L":
self.im_info["transparency"] = i16(s)
elif self.im_mode == "RGB":
self.im_info["transparency"] = i16(s), i16(s[2:]), i16(s[4:])
return s
def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("B", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
def verify(self, endchunk=b"IEND"):
# Simple approach; just calculate checksum for all remaining
# blocks. Must be called directly after open.
cids = []
while True:
try:
cid, pos, length = self.read()
except struct.error:
raise IOError("truncated PNG file")
if cid == endchunk:
break
self.crc(cid, ImageFile._safe_read(self.fp, length))
cids.append(cid)
return cids
def chunk_tRNS(self, pos, length):
# transparency
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
if _simple_palette.match(s):
# tRNS contains only one full-transparent entry,
# other entries are full opaque
i = s.find(b"\0")
if i >= 0:
self.im_info["transparency"] = i
else:
# otherwise, we have a byte string with one alpha value
# for each palette entry
self.im_info["transparency"] = s
elif self.im_mode == "L":
self.im_info["transparency"] = i16(s)
elif self.im_mode == "RGB":
self.im_info["transparency"] = i16(s), i16(s[2:]), i16(s[4:])
return s
def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("b", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
def chunk_tRNS(self, pos, length):
# transparency
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
if _simple_palette.match(s):
i = s.find(b"\0")
if i >= 0:
self.im_info["transparency"] = i
elif _null_palette.match(s):
self.im_info["transparency"] = 0
else:
self.im_info["transparency"] = s
elif self.im_mode == "L":
self.im_info["transparency"] = i16(s)
elif self.im_mode == "RGB":
self.im_info["transparency"] = i16(s), i16(s[2:]), i16(s[4:])
return s
def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("B", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
def verify(self, endchunk=b"IEND"):
# Simple approach; just calculate checksum for all remaining
# blocks. Must be called directly after open.
cids = []
while True:
try:
cid, pos, length = self.read()
except struct.error:
raise IOError("truncated PNG file")
if cid == endchunk:
break
self.crc(cid, ImageFile._safe_read(self.fp, length))
cids.append(cid)
return cids
def chunk_tRNS(self, pos, length):
# transparency
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
if _simple_palette.match(s):
# tRNS contains only one full-transparent entry,
# other entries are full opaque
i = s.find(b"\0")
if i >= 0:
self.im_info["transparency"] = i
else:
# otherwise, we have a byte string with one alpha value
# for each palette entry
self.im_info["transparency"] = s
elif self.im_mode == "L":
self.im_info["transparency"] = i16(s)
elif self.im_mode == "RGB":
self.im_info["transparency"] = i16(s), i16(s[2:]), i16(s[4:])
return s
def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("B", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
def verify(self, endchunk=b"IEND"):
# Simple approach; just calculate checksum for all remaining
# blocks. Must be called directly after open.
cids = []
while True:
try:
cid, pos, length = self.read()
except struct.error:
raise IOError("truncated PNG file")
if cid == endchunk:
break
self.crc(cid, ImageFile._safe_read(self.fp, length))
cids.append(cid)
return cids
def chunk_tRNS(self, pos, length):
# transparency
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
if _simple_palette.match(s):
# tRNS contains only one full-transparent entry,
# other entries are full opaque
i = s.find(b"\0")
if i >= 0:
self.im_info["transparency"] = i
else:
# otherwise, we have a byte string with one alpha value
# for each palette entry
self.im_info["transparency"] = s
elif self.im_mode == "L":
self.im_info["transparency"] = i16(s)
elif self.im_mode == "RGB":
self.im_info["transparency"] = i16(s), i16(s[2:]), i16(s[4:])
return s
def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("B", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
def verify(self, endchunk=b"IEND"):
# Simple approach; just calculate checksum for all remaining
# blocks. Must be called directly after open.
cids = []
while True:
try:
cid, pos, length = self.read()
except struct.error:
raise IOError("truncated PNG file")
if cid == endchunk:
break
self.crc(cid, ImageFile._safe_read(self.fp, length))
cids.append(cid)
return cids
def chunk_tRNS(self, pos, length):
# transparency
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
if _simple_palette.match(s):
# tRNS contains only one full-transparent entry,
# other entries are full opaque
i = s.find(b"\0")
if i >= 0:
self.im_info["transparency"] = i
else:
# otherwise, we have a byte string with one alpha value
# for each palette entry
self.im_info["transparency"] = s
elif self.im_mode == "L":
self.im_info["transparency"] = i16(s)
elif self.im_mode == "RGB":
self.im_info["transparency"] = i16(s), i16(s[2:]), i16(s[4:])
return s
def chunk_tEXt(self, pos, length):
# text
s = ImageFile._safe_read(self.fp, length)
try:
k, v = s.split(b"\0", 1)
except ValueError:
# fallback for broken tEXt tags
k = s
v = b""
if k:
if bytes is not str:
k = k.decode('latin-1', 'strict')
v = v.decode('latin-1', 'replace')
self.im_info[k] = self.im_text[k] = v
self.check_text_memory(len(v))
return s
def DQT(self, marker):
#
# Define quantization table. Support baseline 8-bit tables
# only. Note that there might be more than one table in
# each marker.
# FIXME: The quantization tables can be used to estimate the
# compression quality.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
while len(s):
if len(s) < 65:
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("B", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!
# raise SyntaxError, "bad quantization table element size"
#
# JPEG marker table
def verify(self, endchunk=b"IEND"):
# Simple approach; just calculate checksum for all remaining
# blocks. Must be called directly after open.
cids = []
while True:
try:
cid, pos, length = self.read()
except struct.error:
raise IOError("truncated PNG file")
if cid == endchunk:
break
self.crc(cid, ImageFile._safe_read(self.fp, length))
cids.append(cid)
return cids
def chunk_tRNS(self, pos, length):
# transparency
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
if _simple_palette.match(s):
# tRNS contains only one full-transparent entry,
# other entries are full opaque
i = s.find(b"\0")
if i >= 0:
self.im_info["transparency"] = i
else:
# otherwise, we have a byte string with one alpha value
# for each palette entry
self.im_info["transparency"] = s
elif self.im_mode == "L":
self.im_info["transparency"] = i16(s)
elif self.im_mode == "RGB":
self.im_info["transparency"] = i16(s), i16(s[2:]), i16(s[4:])
return s
def Skip(self, marker):
n = i16(self.fp.read(2))-2
ImageFile._safe_read(self.fp, n)
def COM(self, marker):
#
# Comment marker. Store these in the APP dictionary.
n = i16(self.fp.read(2))-2
s = ImageFile._safe_read(self.fp, n)
self.app["COM"] = s # compatibility
self.applist.append(("COM", s))
def verify(self, endchunk=b"IEND"):
# Simple approach; just calculate checksum for all remaining
# blocks. Must be called directly after open.
cids = []
while True:
cid, pos, length = self.read()
if cid == endchunk:
break
self.crc(cid, ImageFile._safe_read(self.fp, length))
cids.append(cid)
return cids
def chunk_IHDR(self, pos, length):
# image header
s = ImageFile._safe_read(self.fp, length)
self.im_size = i32(s), i32(s[4:])
try:
self.im_mode, self.im_rawmode = _MODES[(i8(s[8]), i8(s[9]))]
except:
pass
if i8(s[12]):
self.im_info["interlace"] = 1
if i8(s[11]):
raise SyntaxError("unknown filter category")
return s
def chunk_PLTE(self, pos, length):
# palette
s = ImageFile._safe_read(self.fp, length)
if self.im_mode == "P":
self.im_palette = "RGB", s
return s
def chunk_gAMA(self, pos, length):
# gamma setting
s = ImageFile._safe_read(self.fp, length)
self.im_info["gamma"] = i32(s) / 100000.0
return s
def chunk_pHYs(self, pos, length):
# pixels per unit
s = ImageFile._safe_read(self.fp, length)
px, py = i32(s), i32(s[4:])
unit = i8(s[8])
if unit == 1: # meter
dpi = int(px * 0.0254 + 0.5), int(py * 0.0254 + 0.5)
self.im_info["dpi"] = dpi
elif unit == 0:
self.im_info["aspect"] = px, py
return s
def chunk_zTXt(self, pos, length):
# compressed text
s = ImageFile._safe_read(self.fp, length)
try:
k, v = s.split(b"\0", 1)
except ValueError:
k = s
v = b""
if v:
comp_method = i8(v[0])
else:
comp_method = 0
if comp_method != 0:
raise SyntaxError("Unknown compression method %s in zTXt chunk" %
comp_method)
try:
v = _safe_zlib_decompress(v[1:])
except zlib.error:
v = b""
if k:
if bytes is not str:
k = k.decode('latin-1', 'strict')
v = v.decode('latin-1', 'replace')
self.im_info[k] = self.im_text[k] = v
self.check_text_memory(len(v))
return s
def chunk_iTXt(self, pos, length):
# international text
r = s = ImageFile._safe_read(self.fp, length)
try:
k, r = r.split(b"\0", 1)
except ValueError:
return s
if len(r) < 2:
return s
cf, cm, r = i8(r[0]), i8(r[1]), r[2:]
try:
lang, tk, v = r.split(b"\0", 2)
except ValueError:
return s
if cf != 0:
if cm == 0:
try:
v = _safe_zlib_decompress(v)
except zlib.error:
return s
else:
return s
if bytes is not str:
try:
k = k.decode("latin-1", "strict")
lang = lang.decode("utf-8", "strict")
tk = tk.decode("utf-8", "strict")
v = v.decode("utf-8", "strict")
except UnicodeError:
return s
self.im_info[k] = self.im_text[k] = iTXt(v, lang, tk)
self.check_text_memory(len(v))
return s
# --------------------------------------------------------------------
# PNG reader
def Skip(self, marker):
n = i16(self.fp.read(2))-2
ImageFile._safe_read(self.fp, n)
