Jpeg2KImagePlugin.py 文件源码

def _open(self):
        sig = self.fp.read(4)
        if sig == b'\xff\x4f\xff\x51':
            self.codec = "j2k"
            self.size, self.mode = _parse_codestream(self.fp)
        else:
            sig = sig + self.fp.read(8)

            if sig == b'\x00\x00\x00\x0cjP  \x0d\x0a\x87\x0a':
                self.codec = "jp2"
                self.size, self.mode = _parse_jp2_header(self.fp)
            else:
                raise SyntaxError('not a JPEG 2000 file')

        if self.size is None or self.mode is None:
            raise SyntaxError('unable to determine size/mode')

        self.reduce = 0
        self.layers = 0

        fd = -1
        length = -1

        try:
            fd = self.fp.fileno()
            length = os.fstat(fd).st_size
        except:
            fd = -1
            try:
                pos = self.fp.tell()
                self.fp.seek(0, 2)
                length = self.fp.tell()
                self.fp.seek(pos, 0)
            except:
                length = -1

        self.tile = [('jpeg2k', (0, 0) + self.size, 0,
                      (self.codec, self.reduce, self.layers, fd, length))]