PngImagePlugin.py 文件源码

def add_text(self, key, value, zip=0):
        """Appends a text chunk.

        :param key: latin-1 encodable text key name
        :param value: value for this key, text or an
           :py:class:`PIL.PngImagePlugin.iTXt` instance
        :param zip: compression flag

        """
        if isinstance(value, iTXt):
            return self.add_itxt(key, value, value.lang, value.tkey, bool(zip))

        # The tEXt chunk stores latin-1 text
        if not isinstance(value, bytes):
            try:
                value = value.encode('latin-1', 'strict')
            except UnicodeError:
                return self.add_itxt(key, value, zip=bool(zip))

        if not isinstance(key, bytes):
            key = key.encode('latin-1', 'strict')

        if zip:
            self.add(b"zTXt", key + b"\0\0" + zlib.compress(value))
        else:
            self.add(b"tEXt", key + b"\0" + value)


# --------------------------------------------------------------------
# PNG image stream (IHDR/IEND)