Merge pull request #3007 from jleclanche/feat/blp

Add support for BLP file format

CHANGES.rst

@@ -1198,7 +1198,7 @@ Changelog (Pillow)
 - Change function declaration to match Tcl_CmdProc type #1966
   [homm]
 
-- Integer overflow checks on all calls to *alloc #1781
+- Integer overflow checks on all calls to \*alloc #1781
   [wiredfool]
 
 - Change equals method on Image so it short circuits #1967

Tests/test_file_blp.py

@@ -0,0 +1,24 @@
+from PIL import Image
+
+from helper import PillowTestCase, unittest
+
+
+class TestFileBlp(PillowTestCase):
+    def test_load_blp2_raw(self):
+        im = Image.open("Tests/images/blp/blp2_raw.blp")
+        target = Image.open("Tests/images/blp/blp2_raw.png")
+        self.assert_image_equal(im, target)
+
+    def test_load_blp2_dxt1(self):
+        im = Image.open("Tests/images/blp/blp2_dxt1.blp")
+        target = Image.open("Tests/images/blp/blp2_dxt1.png")
+        self.assert_image_equal(im, target)
+
+    def test_load_blp2_dxt1a(self):
+        im = Image.open("Tests/images/blp/blp2_dxt1a.blp")
+        target = Image.open("Tests/images/blp/blp2_dxt1a.png")
+        self.assert_image_equal(im, target)
+
+
+if __name__ == "__main__":
+    unittest.main()

src/PIL/BlpImagePlugin.py

@@ -0,0 +1,435 @@
+"""
+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)

src/PIL/__init__.py

@@ -18,7 +18,8 @@ PILLOW_VERSION =  version.__version__
 
 __version__ = PILLOW_VERSION
 
-_plugins = ['BmpImagePlugin',
+_plugins = ['BlpImagePlugin',
+            'BmpImagePlugin',
             'BufrStubImagePlugin',
             'CurImagePlugin',
             'DcxImagePlugin',

tox.ini

@@ -11,4 +11,5 @@ commands =
     {envpython} setup.py clean
     {envpython} setup.py build_ext --inplace
     {envpython} selftest.py
-    {envpython} -m pytest -qq
+    {envpython} -m pytest -qq {posargs}
+deps = pytest