canvas(2)绘制路径，文本，坐标变换

var drawing = document.getElementById('drawing');if(drawing.getContext){//获取绘图的上下文var context  = drawing.getContext('2d');//开始路径context.beginPath();//绘制外圆context.arc(100,100,99,0,2*Math.PI,false);//绘制内圆context.moveTo(194,100);context.arc(100,100,94,0,2*Math.PI,false);//变化原点context.translate(100,100);//旋转指针
//    context.rotate(1);//绘制分针context.moveTo(0,0);context.lineTo(0,-85);//绘制时针context.moveTo(0,0);context.lineTo(-65,0);//绘制文本context.font = 'bold 16px Arial';context.textAlign = 'center';context.textBaseline = 'middle';context.fillText('12',0,-85);//描边路径context.stroke();}