stl_utils.py 文件源码

def _is_ascii_file(data):
    """
    This function returns True if the data represents an ASCII file.

    Please note that a False value does not necessary means that the data
    represents a binary file. It can be a (very *RARE* in real life, but
    can easily be forged) ascii file.
    """
    # Skip header...
    data.seek(BINARY_HEADER)
    size = struct.unpack('<I', data.read(4))[0]
    # Use seek() method to get size of the file.
    data.seek(0, os.SEEK_END)
    file_size = data.tell()
    # Reset to the start of the file.
    data.seek(0)

    if size == 0:  # Odds to get that result from an ASCII file are null...
        print("WARNING! Reported size (facet number) is 0, assuming invalid binary STL file.")
        return False  # Assume binary in this case.

    return (file_size != BINARY_HEADER + 4 + BINARY_STRIDE * size)