var canvas = document.getElementById("face");var cxt = canvas.getContext('2d');var r = 100;   //半径var pointX = 0;  //圆心x坐标var pointY = 0; //圆心y坐标 // 绘制扇形填充 function pie (g,radius,startAngle,endAngle,color,x,y)  {     g.fillStyle = color;     g.beginPath();     g.arc(x,y,radius,startAngle,endAngle,true);     g.closePath();     g.fill(); } var q = 0; function redrawTaiji() {     // 保存状态     cxt.save();     // 清理图像     cxt.clearRect(0,0,canvas.width,canvas.height);     cxt.translate(100,100);     q += Math.PI / 6;     cxt.rotate(q);     cxt.beginPath();     // 绘制两个最大圆     pie(cxt,r,3/4*Math.PI*2,5/4*Math.PI*2,"#FF072A",pointX,pointY);     pie(cxt,r,1/4*Math.PI*2,3/4*Math.PI*2,"#195089",pointX,pointY);     // 绘制两个中圆     pie(cxt,r/2,0,Math.PI*2,"#FF072A",pointX,pointY+r/2);     pie(cxt,r/2,0,Math.PI*2,"#195089",pointX,pointY-r/2);     // 绘制两个最小圆     pie(cxt,r/4,0,Math.PI*2,"#FF072A",pointX,pointY-r/2);     pie(cxt,r/4,0,Math.PI*2,"#195089",pointX,pointY+r/2);     cxt.closePath();     // 恢复状态     cxt.restore(); } function initTaiji() {     redrawTaiji();     setInterval(redrawTaiji,500); } initTaiji();