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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 os
- import struct
- from enum import IntEnum
- from io import BytesIO
-
- from . import Image, ImageFile
- from ._deprecate import deprecate
-
-
- class Format(IntEnum):
- JPEG = 0
-
-
- class Encoding(IntEnum):
- UNCOMPRESSED = 1
- DXT = 2
- UNCOMPRESSED_RAW_BGRA = 3
-
-
- class AlphaEncoding(IntEnum):
- DXT1 = 0
- DXT3 = 1
- DXT5 = 7
-
-
- def __getattr__(name):
- for enum, prefix in {
- Format: "BLP_FORMAT_",
- Encoding: "BLP_ENCODING_",
- AlphaEncoding: "BLP_ALPHA_ENCODING_",
- }.items():
- if name.startswith(prefix):
- name = name[len(prefix) :]
- if name in enum.__members__:
- deprecate(f"{prefix}{name}", 10, f"{enum.__name__}.{name}")
- return enum[name]
- msg = f"module '{__name__}' has no attribute '{name}'"
- raise AttributeError(msg)
-
-
- 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_from("<HHI", data, idx)
-
- 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_from("<8B", block)
- color0, color1 = struct.unpack_from("<HH", block, 8)
-
- (code,) = struct.unpack_from("<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_from("<BB", block)
-
- bits = struct.unpack_from("<6B", block, 2)
- alphacode1 = bits[2] | (bits[3] << 8) | (bits[4] << 16) | (bits[5] << 24)
- alphacode2 = bits[0] | (bits[1] << 8)
-
- color0, color1 = struct.unpack_from("<HH", block, 8)
-
- (code,) = struct.unpack_from("<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
-
-
- def _accept(prefix):
- return prefix[:4] in (b"BLP1", b"BLP2")
-
-
- class BlpImageFile(ImageFile.ImageFile):
- """
- Blizzard Mipmap Format
- """
-
- format = "BLP"
- format_description = "Blizzard Mipmap Format"
-
- def _open(self):
- self.magic = self.fp.read(4)
-
- self.fp.seek(5, os.SEEK_CUR)
- (self._blp_alpha_depth,) = struct.unpack("<b", self.fp.read(1))
-
- self.fp.seek(2, os.SEEK_CUR)
- self._size = struct.unpack("<II", self.fp.read(8))
-
- if self.magic in (b"BLP1", b"BLP2"):
- decoder = self.magic.decode()
- else:
- msg = f"Bad BLP magic {repr(self.magic)}"
- raise BLPFormatError(msg)
-
- self.mode = "RGBA" if self._blp_alpha_depth else "RGB"
- self.tile = [(decoder, (0, 0) + self.size, 0, (self.mode, 0, 1))]
-
-
- class _BLPBaseDecoder(ImageFile.PyDecoder):
- _pulls_fd = True
-
- def decode(self, buffer):
- try:
- self._read_blp_header()
- self._load()
- except struct.error as e:
- msg = "Truncated BLP file"
- raise OSError(msg) from e
- return -1, 0
-
- def _read_blp_header(self):
- self.fd.seek(4)
- (self._blp_compression,) = struct.unpack("<i", self._safe_read(4))
-
- (self._blp_encoding,) = struct.unpack("<b", self._safe_read(1))
- (self._blp_alpha_depth,) = struct.unpack("<b", self._safe_read(1))
- (self._blp_alpha_encoding,) = struct.unpack("<b", self._safe_read(1))
- self.fd.seek(1, os.SEEK_CUR) # mips
-
- self.size = struct.unpack("<II", self._safe_read(8))
-
- if isinstance(self, BLP1Decoder):
- # Only present for BLP1
- (self._blp_encoding,) = struct.unpack("<i", self._safe_read(4))
- self.fd.seek(4, os.SEEK_CUR) # subtype
-
- self._blp_offsets = struct.unpack("<16I", self._safe_read(16 * 4))
- self._blp_lengths = struct.unpack("<16I", self._safe_read(16 * 4))
-
- def _safe_read(self, length):
- return ImageFile._safe_read(self.fd, length)
-
- def _read_palette(self):
- ret = []
- for i in range(256):
- try:
- b, g, r, a = struct.unpack("<4B", self._safe_read(4))
- except struct.error:
- break
- ret.append((b, g, r, a))
- return ret
-
- def _read_bgra(self, palette):
- data = bytearray()
- _data = BytesIO(self._safe_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]
- d = (r, g, b)
- if self._blp_alpha_depth:
- d += (a,)
- data.extend(d)
- return data
-
-
- class BLP1Decoder(_BLPBaseDecoder):
- def _load(self):
- if self._blp_compression == Format.JPEG:
- self._decode_jpeg_stream()
-
- elif self._blp_compression == 1:
- if self._blp_encoding in (4, 5):
- palette = self._read_palette()
- data = self._read_bgra(palette)
- self.set_as_raw(bytes(data))
- else:
- msg = f"Unsupported BLP encoding {repr(self._blp_encoding)}"
- raise BLPFormatError(msg)
- else:
- msg = f"Unsupported BLP compression {repr(self._blp_encoding)}"
- raise BLPFormatError(msg)
-
- def _decode_jpeg_stream(self):
- from .JpegImagePlugin import JpegImageFile
-
- (jpeg_header_size,) = struct.unpack("<I", self._safe_read(4))
- jpeg_header = self._safe_read(jpeg_header_size)
- self._safe_read(self._blp_offsets[0] - self.fd.tell()) # What IS this?
- data = self._safe_read(self._blp_lengths[0])
- data = jpeg_header + data
- data = BytesIO(data)
- image = JpegImageFile(data)
- Image._decompression_bomb_check(image.size)
- if image.mode == "CMYK":
- decoder_name, extents, offset, args = image.tile[0]
- image.tile = [(decoder_name, extents, offset, (args[0], "CMYK"))]
- r, g, b = image.convert("RGB").split()
- image = Image.merge("RGB", (b, g, r))
- self.set_as_raw(image.tobytes())
-
-
- class BLP2Decoder(_BLPBaseDecoder):
- def _load(self):
- palette = self._read_palette()
-
- self.fd.seek(self._blp_offsets[0])
-
- if self._blp_compression == 1:
- # Uncompressed or DirectX compression
-
- if self._blp_encoding == Encoding.UNCOMPRESSED:
- data = self._read_bgra(palette)
-
- elif self._blp_encoding == Encoding.DXT:
- data = bytearray()
- if self._blp_alpha_encoding == AlphaEncoding.DXT1:
- linesize = (self.size[0] + 3) // 4 * 8
- for yb in range((self.size[1] + 3) // 4):
- for d in decode_dxt1(
- self._safe_read(linesize), alpha=bool(self._blp_alpha_depth)
- ):
- data += d
-
- elif self._blp_alpha_encoding == AlphaEncoding.DXT3:
- linesize = (self.size[0] + 3) // 4 * 16
- for yb in range((self.size[1] + 3) // 4):
- for d in decode_dxt3(self._safe_read(linesize)):
- data += d
-
- elif self._blp_alpha_encoding == AlphaEncoding.DXT5:
- linesize = (self.size[0] + 3) // 4 * 16
- for yb in range((self.size[1] + 3) // 4):
- for d in decode_dxt5(self._safe_read(linesize)):
- data += d
- else:
- msg = f"Unsupported alpha encoding {repr(self._blp_alpha_encoding)}"
- raise BLPFormatError(msg)
- else:
- msg = f"Unknown BLP encoding {repr(self._blp_encoding)}"
- raise BLPFormatError(msg)
-
- else:
- msg = f"Unknown BLP compression {repr(self._blp_compression)}"
- raise BLPFormatError(msg)
-
- self.set_as_raw(bytes(data))
-
-
- class BLPEncoder(ImageFile.PyEncoder):
- _pushes_fd = True
-
- def _write_palette(self):
- data = b""
- palette = self.im.getpalette("RGBA", "RGBA")
- for i in range(256):
- r, g, b, a = palette[i * 4 : (i + 1) * 4]
- data += struct.pack("<4B", b, g, r, a)
- return data
-
- def encode(self, bufsize):
- palette_data = self._write_palette()
-
- offset = 20 + 16 * 4 * 2 + len(palette_data)
- data = struct.pack("<16I", offset, *((0,) * 15))
-
- w, h = self.im.size
- data += struct.pack("<16I", w * h, *((0,) * 15))
-
- data += palette_data
-
- for y in range(h):
- for x in range(w):
- data += struct.pack("<B", self.im.getpixel((x, y)))
-
- return len(data), 0, data
-
-
- def _save(im, fp, filename, save_all=False):
- if im.mode != "P":
- msg = "Unsupported BLP image mode"
- raise ValueError(msg)
-
- magic = b"BLP1" if im.encoderinfo.get("blp_version") == "BLP1" else b"BLP2"
- fp.write(magic)
-
- fp.write(struct.pack("<i", 1)) # Uncompressed or DirectX compression
- fp.write(struct.pack("<b", Encoding.UNCOMPRESSED))
- fp.write(struct.pack("<b", 1 if im.palette.mode == "RGBA" else 0))
- fp.write(struct.pack("<b", 0)) # alpha encoding
- fp.write(struct.pack("<b", 0)) # mips
- fp.write(struct.pack("<II", *im.size))
- if magic == b"BLP1":
- fp.write(struct.pack("<i", 5))
- fp.write(struct.pack("<i", 0))
-
- ImageFile._save(im, fp, [("BLP", (0, 0) + im.size, 0, im.mode)])
-
-
- Image.register_open(BlpImageFile.format, BlpImageFile, _accept)
- Image.register_extension(BlpImageFile.format, ".blp")
- Image.register_decoder("BLP1", BLP1Decoder)
- Image.register_decoder("BLP2", BLP2Decoder)
-
- Image.register_save(BlpImageFile.format, _save)
- Image.register_encoder("BLP", BLPEncoder)
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