477 lines
15 KiB
Python
477 lines
15 KiB
Python
"""
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Blizzard Mipmap Format (.blp)
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Jerome Leclanche <jerome@leclan.ch>
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The contents of this file are hereby released in the public domain (CC0)
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Full text of the CC0 license:
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https://creativecommons.org/publicdomain/zero/1.0/
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BLP1 files, used mostly in Warcraft III, are not fully supported.
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All types of BLP2 files used in World of Warcraft are supported.
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The BLP file structure consists of a header, up to 16 mipmaps of the
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texture
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Texture sizes must be powers of two, though the two dimensions do
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not have to be equal; 512x256 is valid, but 512x200 is not.
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The first mipmap (mipmap #0) is the full size image; each subsequent
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mipmap halves both dimensions. The final mipmap should be 1x1.
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BLP files come in many different flavours:
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* JPEG-compressed (type == 0) - only supported for BLP1.
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* RAW images (type == 1, encoding == 1). Each mipmap is stored as an
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array of 8-bit values, one per pixel, left to right, top to bottom.
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Each value is an index to the palette.
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* DXT-compressed (type == 1, encoding == 2):
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- DXT1 compression is used if alpha_encoding == 0.
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- An additional alpha bit is used if alpha_depth == 1.
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- DXT3 compression is used if alpha_encoding == 1.
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- DXT5 compression is used if alpha_encoding == 7.
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"""
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from __future__ import annotations
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import os
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import struct
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from enum import IntEnum
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from io import BytesIO
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from . import Image, ImageFile
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class Format(IntEnum):
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JPEG = 0
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class Encoding(IntEnum):
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UNCOMPRESSED = 1
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DXT = 2
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UNCOMPRESSED_RAW_BGRA = 3
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class AlphaEncoding(IntEnum):
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DXT1 = 0
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DXT3 = 1
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DXT5 = 7
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def unpack_565(i):
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return ((i >> 11) & 0x1F) << 3, ((i >> 5) & 0x3F) << 2, (i & 0x1F) << 3
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def decode_dxt1(data, alpha=False):
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"""
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input: one "row" of data (i.e. will produce 4*width pixels)
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"""
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blocks = len(data) // 8 # number of blocks in row
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ret = (bytearray(), bytearray(), bytearray(), bytearray())
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for block in range(blocks):
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# Decode next 8-byte block.
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idx = block * 8
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color0, color1, bits = struct.unpack_from("<HHI", data, idx)
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r0, g0, b0 = unpack_565(color0)
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r1, g1, b1 = unpack_565(color1)
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# Decode this block into 4x4 pixels
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# Accumulate the results onto our 4 row accumulators
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for j in range(4):
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for i in range(4):
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# get next control op and generate a pixel
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control = bits & 3
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bits = bits >> 2
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a = 0xFF
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if control == 0:
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r, g, b = r0, g0, b0
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elif control == 1:
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r, g, b = r1, g1, b1
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elif control == 2:
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if color0 > color1:
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r = (2 * r0 + r1) // 3
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g = (2 * g0 + g1) // 3
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b = (2 * b0 + b1) // 3
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else:
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r = (r0 + r1) // 2
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g = (g0 + g1) // 2
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b = (b0 + b1) // 2
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elif control == 3:
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if color0 > color1:
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r = (2 * r1 + r0) // 3
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g = (2 * g1 + g0) // 3
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b = (2 * b1 + b0) // 3
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else:
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r, g, b, a = 0, 0, 0, 0
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if alpha:
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ret[j].extend([r, g, b, a])
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else:
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ret[j].extend([r, g, b])
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return ret
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def decode_dxt3(data):
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"""
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input: one "row" of data (i.e. will produce 4*width pixels)
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"""
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blocks = len(data) // 16 # number of blocks in row
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ret = (bytearray(), bytearray(), bytearray(), bytearray())
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for block in range(blocks):
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idx = block * 16
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block = data[idx : idx + 16]
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# Decode next 16-byte block.
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bits = struct.unpack_from("<8B", block)
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color0, color1 = struct.unpack_from("<HH", block, 8)
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(code,) = struct.unpack_from("<I", block, 12)
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r0, g0, b0 = unpack_565(color0)
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r1, g1, b1 = unpack_565(color1)
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for j in range(4):
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high = False # Do we want the higher bits?
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for i in range(4):
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alphacode_index = (4 * j + i) // 2
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a = bits[alphacode_index]
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if high:
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high = False
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a >>= 4
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else:
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high = True
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a &= 0xF
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a *= 17 # We get a value between 0 and 15
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color_code = (code >> 2 * (4 * j + i)) & 0x03
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if color_code == 0:
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r, g, b = r0, g0, b0
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elif color_code == 1:
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r, g, b = r1, g1, b1
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elif color_code == 2:
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r = (2 * r0 + r1) // 3
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g = (2 * g0 + g1) // 3
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b = (2 * b0 + b1) // 3
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elif color_code == 3:
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r = (2 * r1 + r0) // 3
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g = (2 * g1 + g0) // 3
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b = (2 * b1 + b0) // 3
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ret[j].extend([r, g, b, a])
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return ret
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def decode_dxt5(data):
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"""
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input: one "row" of data (i.e. will produce 4 * width pixels)
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"""
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blocks = len(data) // 16 # number of blocks in row
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ret = (bytearray(), bytearray(), bytearray(), bytearray())
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for block in range(blocks):
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idx = block * 16
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block = data[idx : idx + 16]
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# Decode next 16-byte block.
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a0, a1 = struct.unpack_from("<BB", block)
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bits = struct.unpack_from("<6B", block, 2)
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alphacode1 = bits[2] | (bits[3] << 8) | (bits[4] << 16) | (bits[5] << 24)
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alphacode2 = bits[0] | (bits[1] << 8)
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color0, color1 = struct.unpack_from("<HH", block, 8)
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(code,) = struct.unpack_from("<I", block, 12)
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r0, g0, b0 = unpack_565(color0)
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r1, g1, b1 = unpack_565(color1)
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for j in range(4):
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for i in range(4):
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# get next control op and generate a pixel
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alphacode_index = 3 * (4 * j + i)
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if alphacode_index <= 12:
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alphacode = (alphacode2 >> alphacode_index) & 0x07
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elif alphacode_index == 15:
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alphacode = (alphacode2 >> 15) | ((alphacode1 << 1) & 0x06)
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else: # alphacode_index >= 18 and alphacode_index <= 45
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alphacode = (alphacode1 >> (alphacode_index - 16)) & 0x07
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if alphacode == 0:
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a = a0
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elif alphacode == 1:
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a = a1
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elif a0 > a1:
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a = ((8 - alphacode) * a0 + (alphacode - 1) * a1) // 7
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elif alphacode == 6:
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a = 0
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elif alphacode == 7:
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a = 255
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else:
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a = ((6 - alphacode) * a0 + (alphacode - 1) * a1) // 5
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color_code = (code >> 2 * (4 * j + i)) & 0x03
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if color_code == 0:
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r, g, b = r0, g0, b0
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elif color_code == 1:
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r, g, b = r1, g1, b1
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elif color_code == 2:
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r = (2 * r0 + r1) // 3
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g = (2 * g0 + g1) // 3
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b = (2 * b0 + b1) // 3
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elif color_code == 3:
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r = (2 * r1 + r0) // 3
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g = (2 * g1 + g0) // 3
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b = (2 * b1 + b0) // 3
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ret[j].extend([r, g, b, a])
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return ret
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class BLPFormatError(NotImplementedError):
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pass
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def _accept(prefix):
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return prefix[:4] in (b"BLP1", b"BLP2")
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class BlpImageFile(ImageFile.ImageFile):
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"""
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Blizzard Mipmap Format
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"""
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format = "BLP"
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format_description = "Blizzard Mipmap Format"
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def _open(self):
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self.magic = self.fp.read(4)
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self.fp.seek(5, os.SEEK_CUR)
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(self._blp_alpha_depth,) = struct.unpack("<b", self.fp.read(1))
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self.fp.seek(2, os.SEEK_CUR)
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self._size = struct.unpack("<II", self.fp.read(8))
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if self.magic in (b"BLP1", b"BLP2"):
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decoder = self.magic.decode()
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else:
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msg = f"Bad BLP magic {repr(self.magic)}"
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raise BLPFormatError(msg)
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self._mode = "RGBA" if self._blp_alpha_depth else "RGB"
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self.tile = [(decoder, (0, 0) + self.size, 0, (self.mode, 0, 1))]
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class _BLPBaseDecoder(ImageFile.PyDecoder):
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_pulls_fd = True
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def decode(self, buffer):
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try:
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self._read_blp_header()
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self._load()
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except struct.error as e:
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msg = "Truncated BLP file"
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raise OSError(msg) from e
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return -1, 0
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def _read_blp_header(self):
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self.fd.seek(4)
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(self._blp_compression,) = struct.unpack("<i", self._safe_read(4))
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(self._blp_encoding,) = struct.unpack("<b", self._safe_read(1))
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(self._blp_alpha_depth,) = struct.unpack("<b", self._safe_read(1))
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(self._blp_alpha_encoding,) = struct.unpack("<b", self._safe_read(1))
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self.fd.seek(1, os.SEEK_CUR) # mips
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self.size = struct.unpack("<II", self._safe_read(8))
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if isinstance(self, BLP1Decoder):
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# Only present for BLP1
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(self._blp_encoding,) = struct.unpack("<i", self._safe_read(4))
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self.fd.seek(4, os.SEEK_CUR) # subtype
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self._blp_offsets = struct.unpack("<16I", self._safe_read(16 * 4))
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self._blp_lengths = struct.unpack("<16I", self._safe_read(16 * 4))
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def _safe_read(self, length):
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return ImageFile._safe_read(self.fd, length)
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def _read_palette(self):
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ret = []
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for i in range(256):
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try:
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b, g, r, a = struct.unpack("<4B", self._safe_read(4))
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except struct.error:
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break
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ret.append((b, g, r, a))
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return ret
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def _read_bgra(self, palette):
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data = bytearray()
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_data = BytesIO(self._safe_read(self._blp_lengths[0]))
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while True:
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try:
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(offset,) = struct.unpack("<B", _data.read(1))
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except struct.error:
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break
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b, g, r, a = palette[offset]
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d = (r, g, b)
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if self._blp_alpha_depth:
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d += (a,)
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data.extend(d)
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return data
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class BLP1Decoder(_BLPBaseDecoder):
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def _load(self):
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if self._blp_compression == Format.JPEG:
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self._decode_jpeg_stream()
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elif self._blp_compression == 1:
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if self._blp_encoding in (4, 5):
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palette = self._read_palette()
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data = self._read_bgra(palette)
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self.set_as_raw(data)
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else:
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msg = f"Unsupported BLP encoding {repr(self._blp_encoding)}"
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raise BLPFormatError(msg)
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else:
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msg = f"Unsupported BLP compression {repr(self._blp_encoding)}"
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raise BLPFormatError(msg)
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def _decode_jpeg_stream(self):
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from .JpegImagePlugin import JpegImageFile
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(jpeg_header_size,) = struct.unpack("<I", self._safe_read(4))
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jpeg_header = self._safe_read(jpeg_header_size)
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self._safe_read(self._blp_offsets[0] - self.fd.tell()) # What IS this?
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data = self._safe_read(self._blp_lengths[0])
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data = jpeg_header + data
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data = BytesIO(data)
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image = JpegImageFile(data)
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Image._decompression_bomb_check(image.size)
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if image.mode == "CMYK":
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decoder_name, extents, offset, args = image.tile[0]
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image.tile = [(decoder_name, extents, offset, (args[0], "CMYK"))]
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r, g, b = image.convert("RGB").split()
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image = Image.merge("RGB", (b, g, r))
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self.set_as_raw(image.tobytes())
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class BLP2Decoder(_BLPBaseDecoder):
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def _load(self):
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palette = self._read_palette()
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self.fd.seek(self._blp_offsets[0])
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if self._blp_compression == 1:
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# Uncompressed or DirectX compression
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if self._blp_encoding == Encoding.UNCOMPRESSED:
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data = self._read_bgra(palette)
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elif self._blp_encoding == Encoding.DXT:
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data = bytearray()
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if self._blp_alpha_encoding == AlphaEncoding.DXT1:
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linesize = (self.size[0] + 3) // 4 * 8
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for yb in range((self.size[1] + 3) // 4):
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for d in decode_dxt1(
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self._safe_read(linesize), alpha=bool(self._blp_alpha_depth)
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):
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data += d
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elif self._blp_alpha_encoding == AlphaEncoding.DXT3:
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linesize = (self.size[0] + 3) // 4 * 16
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for yb in range((self.size[1] + 3) // 4):
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for d in decode_dxt3(self._safe_read(linesize)):
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data += d
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elif self._blp_alpha_encoding == AlphaEncoding.DXT5:
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linesize = (self.size[0] + 3) // 4 * 16
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for yb in range((self.size[1] + 3) // 4):
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for d in decode_dxt5(self._safe_read(linesize)):
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data += d
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else:
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msg = f"Unsupported alpha encoding {repr(self._blp_alpha_encoding)}"
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raise BLPFormatError(msg)
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else:
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msg = f"Unknown BLP encoding {repr(self._blp_encoding)}"
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raise BLPFormatError(msg)
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else:
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msg = f"Unknown BLP compression {repr(self._blp_compression)}"
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raise BLPFormatError(msg)
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self.set_as_raw(data)
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class BLPEncoder(ImageFile.PyEncoder):
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_pushes_fd = True
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def _write_palette(self):
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data = b""
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palette = self.im.getpalette("RGBA", "RGBA")
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for i in range(len(palette) // 4):
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r, g, b, a = palette[i * 4 : (i + 1) * 4]
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data += struct.pack("<4B", b, g, r, a)
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while len(data) < 256 * 4:
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data += b"\x00" * 4
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return data
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def encode(self, bufsize):
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palette_data = self._write_palette()
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offset = 20 + 16 * 4 * 2 + len(palette_data)
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data = struct.pack("<16I", offset, *((0,) * 15))
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w, h = self.im.size
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data += struct.pack("<16I", w * h, *((0,) * 15))
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data += palette_data
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for y in range(h):
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for x in range(w):
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data += struct.pack("<B", self.im.getpixel((x, y)))
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return len(data), 0, data
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def _save(im, fp, filename):
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if im.mode != "P":
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msg = "Unsupported BLP image mode"
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raise ValueError(msg)
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magic = b"BLP1" if im.encoderinfo.get("blp_version") == "BLP1" else b"BLP2"
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fp.write(magic)
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fp.write(struct.pack("<i", 1)) # Uncompressed or DirectX compression
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fp.write(struct.pack("<b", Encoding.UNCOMPRESSED))
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fp.write(struct.pack("<b", 1 if im.palette.mode == "RGBA" else 0))
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fp.write(struct.pack("<b", 0)) # alpha encoding
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fp.write(struct.pack("<b", 0)) # mips
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fp.write(struct.pack("<II", *im.size))
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if magic == b"BLP1":
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fp.write(struct.pack("<i", 5))
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fp.write(struct.pack("<i", 0))
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ImageFile._save(im, fp, [("BLP", (0, 0) + im.size, 0, im.mode)])
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Image.register_open(BlpImageFile.format, BlpImageFile, _accept)
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Image.register_extension(BlpImageFile.format, ".blp")
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Image.register_decoder("BLP1", BLP1Decoder)
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Image.register_decoder("BLP2", BLP2Decoder)
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Image.register_save(BlpImageFile.format, _save)
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Image.register_encoder("BLP", BLPEncoder)
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