示例网站：http://jstopo.top
drawPieText(ctx, w, h){
	if( Array.isArray( this.pieData ) ){
		this.pieData.forEach((obj,indx,ar)=>{
		ctx.beginPath();ctx.setTextAlign("left");
		ctx.setFillStyle(this.deepShadowColors[indx]);
		const metrics = ctx.measureText("● "+obj.text+" "+(obj.part*100).toFixed(1)/1+"%").width,
		len = (h - ar.length*23)/2;
		ctx.fillText("● "+obj.text+" "+(obj.part*100).toFixed(1)/1+"%", w-20-metrics, 10+indx*23+len);
		})
	}
},