PIL.IptcImagePlugin 源代码

#
# The Python Imaging Library.
# $Id$
#
# IPTC/NAA file handling
#
# history:
# 1995-10-01 fl   Created
# 1998-03-09 fl   Cleaned up and added to PIL
# 2002-06-18 fl   Added getiptcinfo helper
#
# Copyright (c) Secret Labs AB 1997-2002.
# Copyright (c) Fredrik Lundh 1995.
#
# See the README file for information on usage and redistribution.
#
import os
import tempfile

from . import Image, ImageFile
from ._binary import i8
from ._binary import i16be as i16
from ._binary import i32be as i32
from ._binary import o8

COMPRESSION = {1: "raw", 5: "jpeg"}

PAD = o8(0) * 4


#
# Helpers


[文档]def i(c):
    return i32((PAD + c)[-4:])


[文档]def dump(c):
    for i in c:
        print("%02x" % i8(i), end=" ")
    print()


##
# Image plugin for IPTC/NAA datastreams.  To read IPTC/NAA fields
# from TIFF and JPEG files, use the <b>getiptcinfo</b> function.


[文档]class IptcImageFile(ImageFile.ImageFile):

    format = "IPTC"
    format_description = "IPTC/NAA"

[文档]    def getint(self, key):
        return i(self.info[key])

[文档]    def field(self):
        #
        # get a IPTC field header
        s = self.fp.read(5)
        if not len(s):
            return None, 0

        tag = s[1], s[2]

        # syntax
        if s[0] != 0x1C or tag[0] < 1 or tag[0] > 9:
            raise SyntaxError("invalid IPTC/NAA file")

        # field size
        size = s[3]
        if size > 132:
            raise OSError("illegal field length in IPTC/NAA file")
        elif size == 128:
            size = 0
        elif size > 128:
            size = i(self.fp.read(size - 128))
        else:
            size = i16(s, 3)

        return tag, size

    def _open(self):

        # load descriptive fields
        while True:
            offset = self.fp.tell()
            tag, size = self.field()
            if not tag or tag == (8, 10):
                break
            if size:
                tagdata = self.fp.read(size)
            else:
                tagdata = None
            if tag in self.info:
                if isinstance(self.info[tag], list):
                    self.info[tag].append(tagdata)
                else:
                    self.info[tag] = [self.info[tag], tagdata]
            else:
                self.info[tag] = tagdata

        # mode
        layers = i8(self.info[(3, 60)][0])
        component = i8(self.info[(3, 60)][1])
        if (3, 65) in self.info:
            id = i8(self.info[(3, 65)][0]) - 1
        else:
            id = 0
        if layers == 1 and not component:
            self.mode = "L"
        elif layers == 3 and component:
            self.mode = "RGB"[id]
        elif layers == 4 and component:
            self.mode = "CMYK"[id]

        # size
        self._size = self.getint((3, 20)), self.getint((3, 30))

        # compression
        try:
            compression = COMPRESSION[self.getint((3, 120))]
        except KeyError as e:
            raise OSError("Unknown IPTC image compression") from e

        # tile
        if tag == (8, 10):
            self.tile = [
                ("iptc", (compression, offset), (0, 0, self.size[0], self.size[1]))
            ]

[文档]    def load(self):

        if len(self.tile) != 1 or self.tile[0][0] != "iptc":
            return ImageFile.ImageFile.load(self)

        type, tile, box = self.tile[0]

        encoding, offset = tile

        self.fp.seek(offset)

        # Copy image data to temporary file
        o_fd, outfile = tempfile.mkstemp(text=False)
        o = os.fdopen(o_fd)
        if encoding == "raw":
            # To simplify access to the extracted file,
            # prepend a PPM header
            o.write("P5\n%d %d\n255\n" % self.size)
        while True:
            type, size = self.field()
            if type != (8, 10):
                break
            while size > 0:
                s = self.fp.read(min(size, 8192))
                if not s:
                    break
                o.write(s)
                size -= len(s)
        o.close()

        try:
            with Image.open(outfile) as _im:
                _im.load()
                self.im = _im.im
        finally:
            try:
                os.unlink(outfile)
            except OSError:
                pass


Image.register_open(IptcImageFile.format, IptcImageFile)

Image.register_extension(IptcImageFile.format, ".iim")


[文档]def getiptcinfo(im):
    """
    Get IPTC information from TIFF, JPEG, or IPTC file.

    :param im: An image containing IPTC data.
    :returns: A dictionary containing IPTC information, or None if
        no IPTC information block was found.
    """
    import io

    from . import JpegImagePlugin, TiffImagePlugin

    data = None

    if isinstance(im, IptcImageFile):
        # return info dictionary right away
        return im.info

    elif isinstance(im, JpegImagePlugin.JpegImageFile):
        # extract the IPTC/NAA resource
        photoshop = im.info.get("photoshop")
        if photoshop:
            data = photoshop.get(0x0404)

    elif isinstance(im, TiffImagePlugin.TiffImageFile):
        # get raw data from the IPTC/NAA tag (PhotoShop tags the data
        # as 4-byte integers, so we cannot use the get method...)
        try:
            data = im.tag.tagdata[TiffImagePlugin.IPTC_NAA_CHUNK]
        except (AttributeError, KeyError):
            pass

    if data is None:
        return None  # no properties

    # create an IptcImagePlugin object without initializing it
    class FakeImage:
        pass

    im = FakeImage()
    im.__class__ = IptcImageFile

    # parse the IPTC information chunk
    im.info = {}
    im.fp = io.BytesIO(data)

    try:
        im._open()
    except (IndexError, KeyError):
        pass  # expected failure

    return im.info