code/priinfo

#!/usr/bin/env python
# priinfo
# Info

import json
import sys

import png


def info_json_out(out, inp):
    """To the writable file `out` write a JSON record for
    each image found on the readable file `inp`.
    """
    while True:
        r = png.Reader(file=inp)
        try:
            w, h, rows, info = r.read()
        except EOFError:
            break
        # Force the entire PNG to be read, so we can read
        # the next one in the stream.
        list(rows)

        json.dump(info, sys.stdout, sort_keys=True, indent="  ")
        sys.stdout.write("\n")


def main(argv=None):
    import argparse
    import sys

    parser = argparse.ArgumentParser()
    parser.add_argument(
        "input", nargs="?", default="-", type=png.cli_open, metavar="PNG"
    )
    args = parser.parse_args()
    return info_json_out(sys.stdout, args.input)


if __name__ == "__main__":
    main()