Pie图的myChart.getDataURL()不能得到Pie的图形内容

描述:当前是关于Echarts图表中的 饼图 示例。
 
            var option = {
            tooltip : {
				formatter: "{a} <br/>{c} {b}"
            },
            toolbox: {
				show: true,
				feature: {
					restore: {show: true},
					dataView: {},
					saveAsImage: {show: true}
				}
            },
            title: {
                text: '',
                subtext:''
            },
            tooltip: {},
            legend: {
                data:[
				
                ]
            },
            series: [
				{

					type: 'pie',

            		center: ['50%', '50%'],    // 默认全局居中
					radius: 125,
					label: {
						normal: {
							show: true,
							position: 'top',
							textStyle: {
								color: 'rgba(0, 0, 0, 1)'
							}
						}
					},
					labelLine: {
						normal: {
							lineStyle: {
								color: 'rgba(0, 0, 0, 1)'
							},
						}
					},
					data: [
						{value:9.31529748151342,name:'值1'},
						{value:71.1291779584463,name:'值2'}
					]
				}

			]
        };

/*
	postImage('e339c4dd-fd64-4e32-ba8c-a98ab607027f', 'DATA_ESTIMATE', 'VALUE_LOCAL', 'null');
    function postImage(sid, vault, imageSn, docSn) {  
		// 向后台发起请求保存图片到指定目录.
		$.ajax({
			type: 'POST',
			dataType: "json",
			url: "x3EChartSaveImageProcess.jsp?objectSid="+sid+"&vault="+vault+"&imageSn="+imageSn+"&docSn="+docSn,
			data: {"picInfo": myChart.getDataURL()},
			success: function() {
				alert('通过post请求传输数据成功!');
			}
		});
	}
*/

/*

*/