PngImagePlugin.py 文件源码

def getchunks(im, **params):
    """Return a list of PNG chunks representing this image."""

    class collector(object):
        data = []

        def write(self, data):
            pass

        def append(self, chunk):
            self.data.append(chunk)

    def append(fp, cid, *data):
        data = b"".join(data)
        hi, lo = Image.core.crc32(data, Image.core.crc32(cid))
        crc = o16(hi) + o16(lo)
        fp.append((cid, data, crc))

    fp = collector()

    try:
        im.encoderinfo = params
        _save(im, fp, None, append)
    finally:
        del im.encoderinfo

    return fp.data


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