"""
Blizzard Mipmap Format (.blp)
Jerome Leclanche
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.
"""
from __future__ import annotations
import abc
import os
import struct
from enum import IntEnum
from io import BytesIO
from typing import IO
from . import Image, ImageFile
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 unpack_565(i: int) -> tuple[int, int, int]:
return ((i >> 11) & 0x1F) << 3, ((i >> 5) & 0x3F) << 2, (i & 0x1F) << 3
def decode_dxt1(
data: bytes, alpha: bool = False
) -> tuple[bytearray, bytearray, bytearray, bytearray]:
"""
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_index in range(blocks):
# Decode next 8-byte block.
idx = block_index * 8
color0, color1, bits = struct.unpack_from("> 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: bytes) -> tuple[bytearray, bytearray, bytearray, bytearray]:
"""
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_index in range(blocks):
idx = block_index * 16
block = data[idx : idx + 16]
# Decode next 16-byte block.
bits = struct.unpack_from("<8B", block)
color0, color1 = struct.unpack_from(">= 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: bytes) -> tuple[bytearray, bytearray, bytearray, bytearray]:
"""
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_index in range(blocks):
idx = block_index * 16
block = data[idx : idx + 16]
# Decode next 16-byte block.
a0, a1 = struct.unpack_from("> 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: bytes) -> bool:
return prefix.startswith((b"BLP1", b"BLP2"))
class BlpImageFile(ImageFile.ImageFile):
"""
Blizzard Mipmap Format
"""
format = "BLP"
format_description = "Blizzard Mipmap Format"
def _open(self) -> None:
assert self.fp is not None
self.magic = self.fp.read(4)
if not _accept(self.magic):
msg = f"Bad BLP magic {repr(self.magic)}"
raise BLPFormatError(msg)
compression = struct.unpack(" tuple[int, int]:
try:
self._read_header()
self._load()
except struct.error as e:
msg = "Truncated BLP file"
raise OSError(msg) from e
return -1, 0
@abc.abstractmethod
def _load(self) -> None:
pass
def _read_header(self) -> None:
self._offsets = struct.unpack("<16I", self._safe_read(16 * 4))
self._lengths = struct.unpack("<16I", self._safe_read(16 * 4))
def _safe_read(self, length: int) -> bytes:
assert self.fd is not None
return ImageFile._safe_read(self.fd, length)
def _read_palette(self) -> list[tuple[int, int, int, int]]:
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: list[tuple[int, int, int, int]], alpha: bool
) -> bytearray:
data = bytearray()
_data = BytesIO(self._safe_read(self._lengths[0]))
while True:
try:
(offset,) = struct.unpack(" None:
self._compression, self._encoding, alpha = self.args
if self._compression == Format.JPEG:
self._decode_jpeg_stream()
elif self._compression == 1:
if self._encoding in (4, 5):
palette = self._read_palette()
data = self._read_bgra(palette, alpha)
self.set_as_raw(data)
else:
msg = f"Unsupported BLP encoding {repr(self._encoding)}"
raise BLPFormatError(msg)
else:
msg = f"Unsupported BLP compression {repr(self._encoding)}"
raise BLPFormatError(msg)
def _decode_jpeg_stream(self) -> None:
from .JpegImagePlugin import JpegImageFile
(jpeg_header_size,) = struct.unpack(" None:
self._compression, self._encoding, alpha, self._alpha_encoding = self.args
palette = self._read_palette()
assert self.fd is not None
self.fd.seek(self._offsets[0])
if self._compression == 1:
# Uncompressed or DirectX compression
if self._encoding == Encoding.UNCOMPRESSED:
data = self._read_bgra(palette, alpha)
elif self._encoding == Encoding.DXT:
data = bytearray()
if self._alpha_encoding == AlphaEncoding.DXT1:
linesize = (self.state.xsize + 3) // 4 * 8
for yb in range((self.state.ysize + 3) // 4):
for d in decode_dxt1(self._safe_read(linesize), alpha):
data += d
elif self._alpha_encoding == AlphaEncoding.DXT3:
linesize = (self.state.xsize + 3) // 4 * 16
for yb in range((self.state.ysize + 3) // 4):
for d in decode_dxt3(self._safe_read(linesize)):
data += d
elif self._alpha_encoding == AlphaEncoding.DXT5:
linesize = (self.state.xsize + 3) // 4 * 16
for yb in range((self.state.ysize + 3) // 4):
for d in decode_dxt5(self._safe_read(linesize)):
data += d
else:
msg = f"Unsupported alpha encoding {repr(self._alpha_encoding)}"
raise BLPFormatError(msg)
else:
msg = f"Unknown BLP encoding {repr(self._encoding)}"
raise BLPFormatError(msg)
else:
msg = f"Unknown BLP compression {repr(self._compression)}"
raise BLPFormatError(msg)
self.set_as_raw(data)
class BLPEncoder(ImageFile.PyEncoder):
_pushes_fd = True
def _write_palette(self) -> bytes:
data = b""
assert self.im is not None
palette = self.im.getpalette("RGBA", "RGBA")
for i in range(len(palette) // 4):
r, g, b, a = palette[i * 4 : (i + 1) * 4]
data += struct.pack("<4B", b, g, r, a)
while len(data) < 256 * 4:
data += b"\x00" * 4
return data
def encode(self, bufsize: int) -> tuple[int, int, bytes]:
palette_data = self._write_palette()
offset = 20 + 16 * 4 * 2 + len(palette_data)
data = struct.pack("<16I", offset, *((0,) * 15))
assert self.im is not None
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(" None:
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)
assert im.palette is not None
fp.write(struct.pack("