Render single box line.

def _render_line(self, line, settings):
        """
        Render single box line.
        """
        s = self._es(settings, self.SETTING_WIDTH, self.SETTING_FLAG_BORDER, self.SETTING_MARGIN, self.SETTING_MARGIN_LEFT, self.SETTING_MARGIN_RIGHT)
        width_content = self.calculate_width_widget_int(**s)

        s = self._es_content(settings)
        s[self.SETTING_WIDTH] = width_content
        line = self.fmt_content(line, **s)

        s = self._es_text(settings, settings[self.SETTING_TEXT_FORMATING])
        line = self.fmt_text(line, **s)

        s = self._es(settings, self.SETTING_BORDER_STYLE)
        bchar = self.bchar('v', 'm', **s)

        s = self._es_text(settings, settings[self.SETTING_BORDER_FORMATING])
        bchar = self.fmt_text(bchar, **s)

        line = '{}{}{}'.format(bchar, line, bchar)
        s = self._es_margin(settings)
        line = self.fmt_margin(line, **s)
        return line