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Combined BMP RLE decoders
This commit is contained in:
Andrew Murray
parent
78430b9549
commit
6c8234bef3
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@ -211,10 +211,8 @@ class BmpImageFile(ImageFile.ImageFile):
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elif file_info["compression"] == self.RAW:
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if file_info["bits"] == 32 and header == 22: # 32-bit .cur offset
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raw_mode, self.mode = "BGRA", "RGBA"
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elif file_info["compression"] == self.RLE8:
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decoder_name = "bmp_rle8"
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elif file_info["compression"] == self.RLE4:
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decoder_name = "bmp_rle4"
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elif file_info["compression"] in (self.RLE8, self.RLE4):
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decoder_name = "bmp_rle"
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else:
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raise OSError(f"Unsupported BMP compression ({file_info['compression']})")
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@ -252,16 +250,18 @@ class BmpImageFile(ImageFile.ImageFile):
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# ---------------------------- Finally set the tile data for the plugin
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self.info["compression"] = file_info["compression"]
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args = [raw_mode]
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if decoder_name == "bmp_rle":
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args.append(file_info["compression"] == self.RLE4)
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else:
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args.append(((file_info["width"] * file_info["bits"] + 31) >> 3) & (~3))
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args.append(file_info["direction"])
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self.tile = [
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(
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decoder_name,
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(0, 0, file_info["width"], file_info["height"]),
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offset or self.fp.tell(),
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(
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raw_mode,
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((file_info["width"] * file_info["bits"] + 31) >> 3) & (~3),
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file_info["direction"],
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),
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tuple(args),
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)
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]
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@ -278,10 +278,11 @@ class BmpImageFile(ImageFile.ImageFile):
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self._bitmap(offset=offset)
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class BmpRle8Decoder(ImageFile.PyDecoder):
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class BmpRleDecoder(ImageFile.PyDecoder):
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_pulls_fd = True
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def decode(self, buffer):
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rle4 = self.args[1]
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data = bytearray()
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x = 0
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while len(data) < self.state.xsize * self.state.ysize:
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@ -295,9 +296,19 @@ class BmpRle8Decoder(ImageFile.PyDecoder):
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if x + num_pixels > self.state.xsize:
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# Too much data for row
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num_pixels = max(0, self.state.xsize - x)
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data += byte * num_pixels
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if rle4:
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first_pixel = o8(byte[0] >> 4)
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second_pixel = o8(byte[0] & 0x0F)
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for index in range(num_pixels):
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if index % 2 == 0:
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data += first_pixel
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else:
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data += second_pixel
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else:
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data += byte * num_pixels
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x += num_pixels
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else:
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# absolute mode
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if byte[0] == 0:
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# end of line
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while len(data) % self.state.xsize != 0:
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@ -315,73 +326,18 @@ class BmpRle8Decoder(ImageFile.PyDecoder):
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data += b"\x00" * (right + up * self.state.xsize)
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x = len(data) % self.state.xsize
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else:
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# absolute mode
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bytes_read = self.fd.read(byte[0])
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data += bytes_read
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if len(bytes_read) < byte[0]:
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break
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x += byte[0]
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# align to 16-bit word boundary
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if self.fd.tell() % 2 != 0:
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self.fd.seek(1, os.SEEK_CUR)
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rawmode = "L" if self.mode == "L" else "P"
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self.set_as_raw(bytes(data), (rawmode, 0, self.args[-1]))
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return -1, 0
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class BmpRle4Decoder(ImageFile.PyDecoder):
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_pulls_fd = True
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def decode(self, buffer):
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data = bytearray()
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x = 0
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while len(data) < self.state.xsize * self.state.ysize:
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pixels = self.fd.read(1)
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byte = self.fd.read(1)
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if not pixels or not byte:
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break
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num_pixels = pixels[0]
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if num_pixels:
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# encoded mode
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if x + num_pixels > self.state.xsize:
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# Too much data for row
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num_pixels = max(0, self.state.xsize - x)
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first_pixel = o8(byte[0] >> 4)
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second_pixel = o8(byte[0] & 0x0F)
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for index in range(num_pixels):
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if index % 2 == 0:
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data += first_pixel
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if rle4:
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# 2 pixels per byte
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byte_count = byte[0] // 2
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bytes_read = self.fd.read(byte_count)
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for byte_read in bytes_read:
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data += o8(byte_read >> 4)
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data += o8(byte_read & 0x0F)
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else:
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data += second_pixel
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x += num_pixels
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else:
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if byte[0] == 0:
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# end of line
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while len(data) % self.state.xsize != 0:
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data += b"\x00"
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x = 0
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elif byte[0] == 1:
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# end of bitmap
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break
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elif byte[0] == 2:
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# delta
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bytes_read = self.fd.read(2)
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if len(bytes_read) < 2:
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break
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right, up = self.fd.read(2)
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data += b"\x00" * (right + up * self.state.xsize)
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x = len(data) % self.state.xsize
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else:
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# absolute mode (2 pixels per byte)
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total_bytes_to_read = byte[0] // 2
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bytes_read = self.fd.read(total_bytes_to_read)
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for byte_read in bytes_read:
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first_pixel = o8(byte_read >> 4)
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data += first_pixel
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second_pixel = o8(byte_read & 0x0F)
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data += second_pixel
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if len(bytes_read) < total_bytes_to_read:
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byte_count = byte[0]
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bytes_read = self.fd.read(byte_count)
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data += bytes_read
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if len(bytes_read) < byte_count:
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break
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x += byte[0]
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@ -498,8 +454,7 @@ Image.register_extension(BmpImageFile.format, ".bmp")
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Image.register_mime(BmpImageFile.format, "image/bmp")
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Image.register_decoder("bmp_rle8", BmpRle8Decoder)
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Image.register_decoder("bmp_rle4", BmpRle4Decoder)
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Image.register_decoder("bmp_rle", BmpRleDecoder)
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Image.register_open(DibImageFile.format, DibImageFile, _dib_accept)
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Image.register_save(DibImageFile.format, _dib_save)
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