code: function() {
          if (this.drawing) {
          this.ctx.beginPath();
          this.ctx.moveTo(this.lastPos.x, this.lastPos.y);
          this.ctx.lineTo(this.currentPos.x, this.currentPos.y);
          this.ctx.stroke();
          this.lastPos = this.currentPos;
        }
      }
docs: Render the signature to the canvas