__init__.py 文件源码

def _height_and_width(self):
        """Return a tuple of (terminal height, terminal width).

        Start by trying TIOCGWINSZ (Terminal I/O-Control: Get Window Size),
        falling back to environment variables (LINES, COLUMNS), and returning
        (None, None) if those are unavailable or invalid.

        """
        # tigetnum('lines') and tigetnum('cols') update only if we call
        # setupterm() again.
        for descriptor in self._init_descriptor, sys.__stdout__:
            try:
                return struct.unpack(
                        'hhhh', ioctl(descriptor, TIOCGWINSZ, '\000' * 8))[0:2]
            except IOError:
                # when the output stream or init descriptor is not a tty, such
                # as when when stdout is piped to another program, fe. tee(1),
                # these ioctls will raise IOError
                pass
        try:
            return int(environ.get('LINES')), int(environ.get('COLUMNS'))
        except TypeError:
            return None, None