echart 导出保存图片

var img = new Image();    img.src = myChart.getDataURL({    type:"png",    pixelRatio: 2,    backgroundColor: ‘#fff‘});

downloadWeibo(img,"微博平台-事件传播脉络",myChart.getWidth(),myChart.getHeight());

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var  downloadWeibo=function(img,name,width,height){    console.log(img)

img.onload=function(){        var canvas=document.createElement("canvas");        console.log($(img).width());        console.log($(img).height());        canvas.width=width*2;        canvas.height=height*2;        var ctx=canvas.getContext(‘2d‘);        ctx.drawImage(img,0,0);        canvas.toBlob(function(blob) {            saveAs(                blob                , name+".png"            );        }, "image/png");    }

}