/usr/lib/python2.7/dist-packages/PIL/BlpImagePlugin.py is in python-pil 5.1.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Blizzard Mipmap Format (.blp)
Jerome Leclanche <jerome@leclan.ch>
The contents of this file are hereby released in the public domain (CC0)
Full text of the CC0 license:
https://creativecommons.org/publicdomain/zero/1.0/
BLP1 files, used mostly in Warcraft III, are not fully supported.
All types of BLP2 files used in World of Warcraft are supported.
The BLP file structure consists of a header, up to 16 mipmaps of the
texture
Texture sizes must be powers of two, though the two dimensions do
not have to be equal; 512x256 is valid, but 512x200 is not.
The first mipmap (mipmap #0) is the full size image; each subsequent
mipmap halves both dimensions. The final mipmap should be 1x1.
BLP files come in many different flavours:
* JPEG-compressed (type == 0) - only supported for BLP1.
* RAW images (type == 1, encoding == 1). Each mipmap is stored as an
array of 8-bit values, one per pixel, left to right, top to bottom.
Each value is an index to the palette.
* DXT-compressed (type == 1, encoding == 2):
- DXT1 compression is used if alpha_encoding == 0.
- An additional alpha bit is used if alpha_depth == 1.
- DXT3 compression is used if alpha_encoding == 1.
- DXT5 compression is used if alpha_encoding == 7.
"""
import struct
from io import BytesIO
from . import Image, ImageFile
BLP_FORMAT_JPEG = 0
BLP_ENCODING_UNCOMPRESSED = 1
BLP_ENCODING_DXT = 2
BLP_ENCODING_UNCOMPRESSED_RAW_BGRA = 3
BLP_ALPHA_ENCODING_DXT1 = 0
BLP_ALPHA_ENCODING_DXT3 = 1
BLP_ALPHA_ENCODING_DXT5 = 7
def unpack_565(i):
return (
((i >> 11) & 0x1f) << 3,
((i >> 5) & 0x3f) << 2,
(i & 0x1f) << 3
)
def decode_dxt1(data, alpha=False):
"""
input: one "row" of data (i.e. will produce 4*width pixels)
"""
blocks = len(data) // 8 # number of blocks in row
ret = (bytearray(), bytearray(), bytearray(), bytearray())
for block in range(blocks):
# Decode next 8-byte block.
idx = block * 8
color0, color1, bits = struct.unpack("<HHI", data[idx:idx + 8])
r0, g0, b0 = unpack_565(color0)
r1, g1, b1 = unpack_565(color1)
# Decode this block into 4x4 pixels
# Accumulate the results onto our 4 row accumulators
for j in range(4):
for i in range(4):
# get next control op and generate a pixel
control = bits & 3
bits = bits >> 2
a = 0xFF
if control == 0:
r, g, b = r0, g0, b0
elif control == 1:
r, g, b = r1, g1, b1
elif control == 2:
if color0 > color1:
r = (2 * r0 + r1) // 3
g = (2 * g0 + g1) // 3
b = (2 * b0 + b1) // 3
else:
r = (r0 + r1) // 2
g = (g0 + g1) // 2
b = (b0 + b1) // 2
elif control == 3:
if color0 > color1:
r = (2 * r1 + r0) // 3
g = (2 * g1 + g0) // 3
b = (2 * b1 + b0) // 3
else:
r, g, b, a = 0, 0, 0, 0
if alpha:
ret[j].extend([r, g, b, a])
else:
ret[j].extend([r, g, b])
return ret
def decode_dxt3(data):
"""
input: one "row" of data (i.e. will produce 4*width pixels)
"""
blocks = len(data) // 16 # number of blocks in row
ret = (bytearray(), bytearray(), bytearray(), bytearray())
for block in range(blocks):
idx = block * 16
block = data[idx:idx + 16]
# Decode next 16-byte block.
bits = struct.unpack("<8B", block[:8])
color0, color1 = struct.unpack("<HH", block[8:12])
code, = struct.unpack("<I", block[12:])
r0, g0, b0 = unpack_565(color0)
r1, g1, b1 = unpack_565(color1)
for j in range(4):
high = False # Do we want the higher bits?
for i in range(4):
alphacode_index = (4 * j + i) // 2
a = bits[alphacode_index]
if high:
high = False
a >>= 4
else:
high = True
a &= 0xf
a *= 17 # We get a value between 0 and 15
color_code = (code >> 2 * (4 * j + i)) & 0x03
if color_code == 0:
r, g, b = r0, g0, b0
elif color_code == 1:
r, g, b = r1, g1, b1
elif color_code == 2:
r = (2 * r0 + r1) // 3
g = (2 * g0 + g1) // 3
b = (2 * b0 + b1) // 3
elif color_code == 3:
r = (2 * r1 + r0) // 3
g = (2 * g1 + g0) // 3
b = (2 * b1 + b0) // 3
ret[j].extend([r, g, b, a])
return ret
def decode_dxt5(data):
"""
input: one "row" of data (i.e. will produce 4 * width pixels)
"""
blocks = len(data) // 16 # number of blocks in row
ret = (bytearray(), bytearray(), bytearray(), bytearray())
for block in range(blocks):
idx = block * 16
block = data[idx:idx + 16]
# Decode next 16-byte block.
a0, a1 = struct.unpack("<BB", block[:2])
bits = struct.unpack("<6B", block[2:8])
alphacode1 = (
bits[2] | (bits[3] << 8) | (bits[4] << 16) | (bits[5] << 24)
)
alphacode2 = bits[0] | (bits[1] << 8)
color0, color1 = struct.unpack("<HH", block[8:12])
code, = struct.unpack("<I", block[12:])
r0, g0, b0 = unpack_565(color0)
r1, g1, b1 = unpack_565(color1)
for j in range(4):
for i in range(4):
# get next control op and generate a pixel
alphacode_index = 3 * (4 * j + i)
if alphacode_index <= 12:
alphacode = (alphacode2 >> alphacode_index) & 0x07
elif alphacode_index == 15:
alphacode = (alphacode2 >> 15) | ((alphacode1 << 1) & 0x06)
else: # alphacode_index >= 18 and alphacode_index <= 45
alphacode = (alphacode1 >> (alphacode_index - 16)) & 0x07
if alphacode == 0:
a = a0
elif alphacode == 1:
a = a1
elif a0 > a1:
a = ((8 - alphacode) * a0 + (alphacode - 1) * a1) // 7
elif alphacode == 6:
a = 0
elif alphacode == 7:
a = 255
else:
a = ((6 - alphacode) * a0 + (alphacode - 1) * a1) // 5
color_code = (code >> 2 * (4 * j + i)) & 0x03
if color_code == 0:
r, g, b = r0, g0, b0
elif color_code == 1:
r, g, b = r1, g1, b1
elif color_code == 2:
r = (2 * r0 + r1) // 3
g = (2 * g0 + g1) // 3
b = (2 * b0 + b1) // 3
elif color_code == 3:
r = (2 * r1 + r0) // 3
g = (2 * g1 + g0) // 3
b = (2 * b1 + b0) // 3
ret[j].extend([r, g, b, a])
return ret
class BLPFormatError(NotImplementedError):
pass
class BlpImageFile(ImageFile.ImageFile):
"""
Blizzard Mipmap Format
"""
format = "BLP"
format_description = "Blizzard Mipmap Format"
def _open(self):
self.magic = self.fp.read(4)
self._read_blp_header()
if self.magic == b"BLP1":
decoder = "BLP1"
self.mode = "RGB"
elif self.magic == b"BLP2":
decoder = "BLP2"
self.mode = "RGBA" if self._blp_alpha_depth else "RGB"
else:
raise BLPFormatError("Bad BLP magic %r" % (self.magic))
self.tile = [
(decoder, (0, 0) + self.size, 0, (self.mode, 0, 1))
]
def _read_blp_header(self):
self._blp_compression, = struct.unpack("<i", self.fp.read(4))
self._blp_encoding, = struct.unpack("<b", self.fp.read(1))
self._blp_alpha_depth, = struct.unpack("<b", self.fp.read(1))
self._blp_alpha_encoding, = struct.unpack("<b", self.fp.read(1))
self._blp_mips, = struct.unpack("<b", self.fp.read(1))
self.size = struct.unpack("<II", self.fp.read(8))
if self.magic == b"BLP1":
# Only present for BLP1
self._blp_encoding, = struct.unpack("<i", self.fp.read(4))
self._blp_subtype, = struct.unpack("<i", self.fp.read(4))
self._blp_offsets = struct.unpack("<16I", self.fp.read(16 * 4))
self._blp_lengths = struct.unpack("<16I", self.fp.read(16 * 4))
class _BLPBaseDecoder(ImageFile.PyDecoder):
_pulls_fd = True
def decode(self, buffer):
try:
self.fd.seek(0)
self.magic = self.fd.read(4)
self._read_blp_header()
self._load()
except struct.error:
raise IOError("Truncated Blp file")
return 0, 0
def _read_palette(self):
ret = []
for i in range(256):
try:
b, g, r, a = struct.unpack("<4B", self.fd.read(4))
except struct.error:
break
ret.append((b, g, r, a))
return ret
def _read_blp_header(self):
self._blp_compression, = struct.unpack("<i", self.fd.read(4))
self._blp_encoding, = struct.unpack("<b", self.fd.read(1))
self._blp_alpha_depth, = struct.unpack("<b", self.fd.read(1))
self._blp_alpha_encoding, = struct.unpack("<b", self.fd.read(1))
self._blp_mips, = struct.unpack("<b", self.fd.read(1))
self.size = struct.unpack("<II", self.fd.read(8))
if self.magic == b"BLP1":
# Only present for BLP1
self._blp_encoding, = struct.unpack("<i", self.fd.read(4))
self._blp_subtype, = struct.unpack("<i", self.fd.read(4))
self._blp_offsets = struct.unpack("<16I", self.fd.read(16 * 4))
self._blp_lengths = struct.unpack("<16I", self.fd.read(16 * 4))
class BLP1Decoder(_BLPBaseDecoder):
def _load(self):
if self._blp_compression == BLP_FORMAT_JPEG:
self._decode_jpeg_stream()
elif self._blp_compression == 1:
if self._blp_encoding in (4, 5):
data = bytearray()
palette = self._read_palette()
_data = BytesIO(self.fd.read(self._blp_lengths[0]))
while True:
try:
offset, = struct.unpack("<B", _data.read(1))
except struct.error:
break
b, g, r, a = palette[offset]
data.extend([r, g, b])
self.set_as_raw(bytes(data))
else:
raise BLPFormatError(
"Unsupported BLP encoding %r" % (self._blp_encoding)
)
else:
raise BLPFormatError(
"Unsupported BLP compression %r" % (self._blp_encoding)
)
def _decode_jpeg_stream(self):
from PIL.JpegImagePlugin import JpegImageFile
jpeg_header_size, = struct.unpack("<I", self.fd.read(4))
jpeg_header = self.fd.read(jpeg_header_size)
self.fd.read(self._blp_offsets[0] - self.fd.tell()) # What IS this?
data = self.fd.read(self._blp_lengths[0])
data = jpeg_header + data
data = BytesIO(data)
image = JpegImageFile(data)
self.tile = image.tile # :/
self.fd = image.fp
self.mode = image.mode
class BLP2Decoder(_BLPBaseDecoder):
def _load(self):
palette = self._read_palette()
data = bytearray()
self.fd.seek(self._blp_offsets[0])
if self._blp_compression == 1:
# Uncompressed or DirectX compression
if self._blp_encoding == BLP_ENCODING_UNCOMPRESSED:
_data = BytesIO(self.fd.read(self._blp_lengths[0]))
while True:
try:
offset, = struct.unpack("<B", _data.read(1))
except struct.error:
break
b, g, r, a = palette[offset]
data.extend((r, g, b))
elif self._blp_encoding == BLP_ENCODING_DXT:
if self._blp_alpha_encoding == BLP_ALPHA_ENCODING_DXT1:
linesize = (self.size[0] + 3) // 4 * 8
for yb in range((self.size[1] + 3) // 4):
for d in decode_dxt1(
self.fd.read(linesize),
alpha=bool(self._blp_alpha_depth)
):
data += d
elif self._blp_alpha_encoding == BLP_ALPHA_ENCODING_DXT3:
linesize = (self.size[0] + 3) // 4 * 16
for yb in range((self.size[1] + 3) // 4):
for d in decode_dxt3(self.fd.read(linesize)):
data += d
elif self._blp_alpha_encoding == BLP_ALPHA_ENCODING_DXT5:
linesize = (self.size[0] + 3) // 4 * 16
for yb in range((self.size[1] + 3) // 4):
for d in decode_dxt5(self.fd.read(linesize)):
data += d
else:
raise BLPFormatError("Unsupported alpha encoding %r" % (
self._blp_alpha_encoding
))
else:
raise BLPFormatError(
"Unknown BLP encoding %r" % (self._blp_encoding)
)
else:
raise BLPFormatError(
"Unknown BLP compression %r" % (self._blp_compression)
)
self.set_as_raw(bytes(data))
Image.register_open(
BlpImageFile.format, BlpImageFile, lambda p: p[:4] in (b"BLP1", b"BLP2")
)
Image.register_extension(BlpImageFile.format, ".blp")
Image.register_decoder("BLP1", BLP1Decoder)
Image.register_decoder("BLP2", BLP2Decoder)
|