Perform widget rendering, but do not print anything.

def _render_content(self, content, **settings):
        """
        Perform widget rendering, but do not print anything.
        """
        ocontent = content

        s = self._es_data(settings)
        content = self.fmt_data(content, **s)

        s = self._es_content(settings)
        content = self.fmt_content(content, **s)

        if settings[self.SETTING_TEXT_HIGHLIGHT]:
            s = self._es_text(settings, settings[self.SETTING_TEXT_HIGHLIGHT](ocontent))
        else:
            s = self._es_text(settings, settings[self.SETTING_TEXT_FORMATING])
        content = self.fmt_text(content, **s)

        s = self._es_margin(settings)
        content = self.fmt_margin(content, **s)

        return content