197 lines
6.4 KiB
Python
197 lines
6.4 KiB
Python
import os
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import os.path
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import struct
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from io import BytesIO
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from typing import BinaryIO, Tuple
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from .jbig2 import JBIG2StreamReader, JBIG2StreamWriter
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from .layout import LTImage
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from .pdfcolor import LITERAL_DEVICE_CMYK
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from .pdfcolor import LITERAL_DEVICE_GRAY
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from .pdfcolor import LITERAL_DEVICE_RGB
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from .pdftypes import LITERALS_DCT_DECODE, LITERALS_JBIG2_DECODE, \
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LITERALS_JPX_DECODE
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def align32(x: int) -> int:
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return ((x+3)//4)*4
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class BMPWriter:
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def __init__(
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self,
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fp: BinaryIO,
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bits: int,
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width: int,
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height: int
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) -> None:
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self.fp = fp
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self.bits = bits
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self.width = width
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self.height = height
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if bits == 1:
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ncols = 2
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elif bits == 8:
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ncols = 256
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elif bits == 24:
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ncols = 0
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else:
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raise ValueError(bits)
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self.linesize = align32((self.width*self.bits+7)//8)
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self.datasize = self.linesize * self.height
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headersize = 14+40+ncols*4
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info = struct.pack('<IiiHHIIIIII', 40, self.width, self.height,
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1, self.bits, 0, self.datasize, 0, 0, ncols, 0)
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assert len(info) == 40, str(len(info))
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header = struct.pack('<ccIHHI', b'B', b'M',
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headersize+self.datasize, 0, 0, headersize)
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assert len(header) == 14, str(len(header))
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self.fp.write(header)
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self.fp.write(info)
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if ncols == 2:
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# B&W color table
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for i in (0, 255):
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self.fp.write(struct.pack('BBBx', i, i, i))
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elif ncols == 256:
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# grayscale color table
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for i in range(256):
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self.fp.write(struct.pack('BBBx', i, i, i))
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self.pos0 = self.fp.tell()
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self.pos1 = self.pos0 + self.datasize
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return
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def write_line(self, y: int, data: bytes) -> None:
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self.fp.seek(self.pos1 - (y+1)*self.linesize)
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self.fp.write(data)
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return
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class ImageWriter:
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"""Write image to a file
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Supports various image types: JPEG, JBIG2 and bitmaps
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"""
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def __init__(self, outdir: str) -> None:
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self.outdir = outdir
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if not os.path.exists(self.outdir):
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os.makedirs(self.outdir)
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return
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def export_image(self, image: LTImage) -> str:
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(width, height) = image.srcsize
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is_jbig2 = self.is_jbig2_image(image)
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ext = self._get_image_extension(image, width, height, is_jbig2)
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name, path = self._create_unique_image_name(self.outdir,
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image.name, ext)
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fp = open(path, 'wb')
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if ext == '.jpg':
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raw_data = image.stream.get_rawdata()
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assert raw_data is not None
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if LITERAL_DEVICE_CMYK in image.colorspace:
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from PIL import Image # type: ignore[import]
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from PIL import ImageChops
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ifp = BytesIO(raw_data)
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i = Image.open(ifp)
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i = ImageChops.invert(i)
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i = i.convert('RGB')
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i.save(fp, 'JPEG')
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else:
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fp.write(raw_data)
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elif ext == '.jp2':
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# if we just write the raw data, most image programs
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# that I have tried cannot open the file. However,
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# open and saving with PIL produces a file that
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# seems to be easily opened by other programs
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from PIL import Image
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raw_data = image.stream.get_rawdata()
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ifp = BytesIO(raw_data)
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i = Image.open(ifp)
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i.save(fp, 'JPEG2000')
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elif is_jbig2:
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input_stream = BytesIO()
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input_stream.write(image.stream.get_data())
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input_stream.seek(0)
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reader = JBIG2StreamReader(input_stream)
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segments = reader.get_segments()
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writer = JBIG2StreamWriter(fp)
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writer.write_file(segments)
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elif image.bits == 1:
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bmp = BMPWriter(fp, 1, width, height)
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data = image.stream.get_data()
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i = 0
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width = (width+7)//8
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for y in range(height):
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bmp.write_line(y, data[i:i+width])
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i += width
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elif image.bits == 8 and LITERAL_DEVICE_RGB in image.colorspace:
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bmp = BMPWriter(fp, 24, width, height)
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data = image.stream.get_data()
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i = 0
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width = width*3
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for y in range(height):
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bmp.write_line(y, data[i:i+width])
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i += width
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elif image.bits == 8 and LITERAL_DEVICE_GRAY in image.colorspace:
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bmp = BMPWriter(fp, 8, width, height)
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data = image.stream.get_data()
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i = 0
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for y in range(height):
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bmp.write_line(y, data[i:i+width])
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i += width
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else:
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fp.write(image.stream.get_data())
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fp.close()
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return name
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@staticmethod
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def is_jbig2_image(image: LTImage) -> bool:
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filters = image.stream.get_filters()
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is_jbig2 = False
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for filter_name, params in filters:
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if filter_name in LITERALS_JBIG2_DECODE:
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is_jbig2 = True
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break
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return is_jbig2
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@staticmethod
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def _get_image_extension(
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image: LTImage,
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width: int,
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height: int,
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is_jbig2: bool
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) -> str:
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filters = image.stream.get_filters()
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if len(filters) == 1 and filters[0][0] in LITERALS_DCT_DECODE:
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ext = '.jpg'
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elif len(filters) == 1 and filters[0][0] in LITERALS_JPX_DECODE:
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ext = '.jp2'
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elif is_jbig2:
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ext = '.jb2'
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elif (image.bits == 1 or
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image.bits == 8 and
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(LITERAL_DEVICE_RGB in image.colorspace or
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LITERAL_DEVICE_GRAY in image.colorspace)):
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ext = '.%dx%d.bmp' % (width, height)
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else:
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ext = '.%d.%dx%d.img' % (image.bits, width, height)
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return ext
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@staticmethod
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def _create_unique_image_name(
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dirname: str,
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image_name: str,
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ext: str
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) -> Tuple[str, str]:
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name = image_name + ext
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path = os.path.join(dirname, name)
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img_index = 0
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while os.path.exists(path):
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name = '%s.%d%s' % (image_name, img_index, ext)
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path = os.path.join(dirname, name)
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img_index += 1
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return name, path
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