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Pillow/PIL/DdsImagePlugin.py
Andrew Murray 677b958a7f Health fixes
2016-04-01 21:49:30 +11:00

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"""
A Pillow loader for .dds files (S3TC-compressed aka DXTC)
Jerome Leclanche <jerome@leclan.ch>
Documentation:
http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt
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/
"""
import struct
from io import BytesIO
from PIL import Image, ImageFile
# Magic ("DDS ")
DDS_MAGIC = 0x20534444
# DDS flags
DDSD_CAPS = 0x1
DDSD_HEIGHT = 0x2
DDSD_WIDTH = 0x4
DDSD_PITCH = 0x8
DDSD_PIXELFORMAT = 0x1000
DDSD_MIPMAPCOUNT = 0x20000
DDSD_LINEARSIZE = 0x80000
DDSD_DEPTH = 0x800000
# DDS caps
DDSCAPS_COMPLEX = 0x8
DDSCAPS_TEXTURE = 0x1000
DDSCAPS_MIPMAP = 0x400000
DDSCAPS2_CUBEMAP = 0x200
DDSCAPS2_CUBEMAP_POSITIVEX = 0x400
DDSCAPS2_CUBEMAP_NEGATIVEX = 0x800
DDSCAPS2_CUBEMAP_POSITIVEY = 0x1000
DDSCAPS2_CUBEMAP_NEGATIVEY = 0x2000
DDSCAPS2_CUBEMAP_POSITIVEZ = 0x4000
DDSCAPS2_CUBEMAP_NEGATIVEZ = 0x8000
DDSCAPS2_VOLUME = 0x200000
# Pixel Format
DDPF_ALPHAPIXELS = 0x1
DDPF_ALPHA = 0x2
DDPF_FOURCC = 0x4
DDPF_PALETTEINDEXED8 = 0x20
DDPF_RGB = 0x40
DDPF_LUMINANCE = 0x20000
# dds.h
DDS_FOURCC = DDPF_FOURCC
DDS_RGB = DDPF_RGB
DDS_RGBA = DDPF_RGB | DDPF_ALPHAPIXELS
DDS_LUMINANCE = DDPF_LUMINANCE
DDS_LUMINANCEA = DDPF_LUMINANCE | DDPF_ALPHAPIXELS
DDS_ALPHA = DDPF_ALPHA
DDS_PAL8 = DDPF_PALETTEINDEXED8
DDS_HEADER_FLAGS_TEXTURE = (DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH |
DDSD_PIXELFORMAT)
DDS_HEADER_FLAGS_MIPMAP = DDSD_MIPMAPCOUNT
DDS_HEADER_FLAGS_VOLUME = DDSD_DEPTH
DDS_HEADER_FLAGS_PITCH = DDSD_PITCH
DDS_HEADER_FLAGS_LINEARSIZE = DDSD_LINEARSIZE
DDS_HEIGHT = DDSD_HEIGHT
DDS_WIDTH = DDSD_WIDTH
DDS_SURFACE_FLAGS_TEXTURE = DDSCAPS_TEXTURE
DDS_SURFACE_FLAGS_MIPMAP = DDSCAPS_COMPLEX | DDSCAPS_MIPMAP
DDS_SURFACE_FLAGS_CUBEMAP = DDSCAPS_COMPLEX
DDS_CUBEMAP_POSITIVEX = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_POSITIVEX
DDS_CUBEMAP_NEGATIVEX = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_NEGATIVEX
DDS_CUBEMAP_POSITIVEY = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_POSITIVEY
DDS_CUBEMAP_NEGATIVEY = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_NEGATIVEY
DDS_CUBEMAP_POSITIVEZ = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_POSITIVEZ
DDS_CUBEMAP_NEGATIVEZ = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_NEGATIVEZ
# DXT1
DXT1_FOURCC = 0x31545844
# DXT3
DXT3_FOURCC = 0x33545844
# DXT5
DXT5_FOURCC = 0x35545844
def _decode565(bits):
a = ((bits >> 11) & 0x1f) << 3
b = ((bits >> 5) & 0x3f) << 2
c = (bits & 0x1f) << 3
return a, b, c
def _c2a(a, b):
return (2 * a + b) // 3
def _c2b(a, b):
return (a + b) // 2
def _c3(a, b):
return (2 * b + a) // 3
def _dxt1(data, width, height):
# TODO implement this function as pixel format in decode.c
ret = bytearray(4 * width * height)
for y in range(0, height, 4):
for x in range(0, width, 4):
color0, color1, bits = struct.unpack("<HHI", data.read(8))
r0, g0, b0 = _decode565(color0)
r1, g1, b1 = _decode565(color1)
# Decode this block into 4x4 pixels
for j in range(4):
for i in range(4):
# get next control op and generate a pixel
control = bits & 3
bits = bits >> 2
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, g, b = _c2a(r0, r1), _c2a(g0, g1), _c2a(b0, b1)
else:
r, g, b = _c2b(r0, r1), _c2b(g0, g1), _c2b(b0, b1)
elif control == 3:
if color0 > color1:
r, g, b = _c3(r0, r1), _c3(g0, g1), _c3(b0, b1)
else:
r, g, b = 0, 0, 0
idx = 4 * ((y + j) * width + (x + i))
ret[idx:idx+4] = struct.pack('4B', r, g, b, 255)
return bytes(ret)
def _dxtc_alpha(a0, a1, ac0, ac1, ai):
if ai <= 12:
ac = (ac0 >> ai) & 7
elif ai == 15:
ac = (ac0 >> 15) | ((ac1 << 1) & 6)
else:
ac = (ac1 >> (ai - 16)) & 7
if ac == 0:
alpha = a0
elif ac == 1:
alpha = a1
elif a0 > a1:
alpha = ((8 - ac) * a0 + (ac - 1) * a1) // 7
elif ac == 6:
alpha = 0
elif ac == 7:
alpha = 0xff
else:
alpha = ((6 - ac) * a0 + (ac - 1) * a1) // 5
return alpha
def _dxt5(data, width, height):
# TODO implement this function as pixel format in decode.c
ret = bytearray(4 * width * height)
for y in range(0, height, 4):
for x in range(0, width, 4):
a0, a1, ac0, ac1, c0, c1, code = struct.unpack("<2BHI2HI",
data.read(16))
r0, g0, b0 = _decode565(c0)
r1, g1, b1 = _decode565(c1)
for j in range(4):
for i in range(4):
ai = 3 * (4 * j + i)
alpha = _dxtc_alpha(a0, a1, ac0, ac1, ai)
cc = (code >> 2 * (4 * j + i)) & 3
if cc == 0:
r, g, b = r0, g0, b0
elif cc == 1:
r, g, b = r1, g1, b1
elif cc == 2:
r, g, b = _c2a(r0, r1), _c2a(g0, g1), _c2a(b0, b1)
elif cc == 3:
r, g, b = _c3(r0, r1), _c3(g0, g1), _c3(b0, b1)
idx = 4 * ((y + j) * width + (x + i))
ret[idx:idx+4] = struct.pack('4B', r, g, b, alpha)
return bytes(ret)
class DdsImageFile(ImageFile.ImageFile):
format = "DDS"
format_description = "DirectDraw Surface"
def _open(self):
magic, header_size = struct.unpack("<II", self.fp.read(8))
if header_size != 124:
raise IOError("Unsupported header size %r" % (header_size))
header_bytes = self.fp.read(header_size - 4)
if len(header_bytes) != 120:
raise IOError("Incomplete header: %s bytes" % len(header_bytes))
header = BytesIO(header_bytes)
flags, height, width = struct.unpack("<3I", header.read(12))
self.size = (width, height)
self.mode = "RGBA"
pitch, depth, mipmaps = struct.unpack("<3I", header.read(12))
reserved = struct.unpack("<11I", header.read(44))
# pixel format
pfsize, pfflags = struct.unpack("<2I", header.read(8))
fourcc = header.read(4)
bitcount, rmask, gmask, bmask, amask = struct.unpack("<5I",
header.read(20))
self.tile = [
("raw", (0, 0) + self.size, 0, (self.mode, 0, 1))
]
if fourcc == b"DXT1":
self.pixel_format = "DXT1"
codec = _dxt1
elif fourcc == b"DXT5":
self.pixel_format = "DXT5"
codec = _dxt5
else:
raise NotImplementedError("Unimplemented pixel format %r" %
(fourcc))
try:
decoded_data = codec(self.fp, self.width, self.height)
except struct.error:
raise IOError("Truncated DDS file")
finally:
self.fp.close()
self.fp = BytesIO(decoded_data)
def load_seek(self, pos):
pass
def _validate(prefix):
return prefix[:4] == b"DDS "
Image.register_open(DdsImageFile.format, DdsImageFile, _validate)
Image.register_extension(DdsImageFile.format, ".dds")
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