def text(self, x, y, txt=''):
        "Output a string"
        txt = self.normalize_text(txt)
        if (self.unifontsubset):
            txt2 = self._escape(UTF8ToUTF16BE(txt, False))
            for uni in UTF8StringToArray(txt):
                self.current_font['subset'].append(uni)
        else:
            txt2 = self._escape(txt)
        s=sprintf('BT %.2f %.2f Td (%s) Tj ET',x*self.k,(self.h-y)*self.k, txt2)
        if(self.underline and txt!=''):
            s+=' '+self._dounderline(x,y,txt)
        if(self.color_flag):
            s='q '+self.text_color+' '+s+' Q'
        self._out(s)
Output a string