Add text watermark (canvas) for the site

Man of few words said, first on the map! !

//添加水印
      function addWaterMarker(str){
        var can = document.createElement('canvas');
        var body = document.body;
        body.appendChild(can);

        can.width=200;
        can.height=100;
        can.style.display='none';

        var cans = can.getContext('2d');
        cans.rotate(-20*Math.PI/180);
        cans.font = "16px Microsoft JhengHei";
        cans.fillStyle = "rgba(17, 17, 17, 0.40)";
        cans.textAlign = 'left';
        cans.textBaseline = 'Middle';
        cans.fillText(str,can.width/4,can.height/2);

        body.style.backgroundImage="url("+can.toDataURL("image/png")+")";

      }
      addWaterMarker ( 'Fengya Ting');