使用www.gstatic.com/charts/loader.js时Wkhtmltopdf不绘制图表

Question

我一直试图以pdf格式输出图表，但由于某种原因，它无法使用图表呈现模板。 使用时。 但是对于一些解决方案，我已经看到他们使用 。但是我想要上层解决方案。

代码

<script type="text/javascript">

  // Load Charts and the corechart and barchart packages.
  function init(){
    //google.charts.load('current','1.0',{'packages':['corechart']});
    //google.charts.setOnLoadCallback(drawChart);
    window.onload = function () {
    google.charts.load('current','1.0',{'packages':['corechart']});
    setTimeout(function(){drawChart();}, 500);
    };
  }

  // Draw the pie chart and bar chart when Charts is loaded.


  function drawChart() {

    var data = new google.visualization.DataTable();
    data.addColumn('string', 'number');
    data.addColumn('number', 'Number of users');
    data.addRows([
      ['Admin', {{ count_4 }}],
      ['Farmers', {{ count_1 }}],
      ['Wholesalers', {{ count_2 }}],
      ['Retailers', {{ count_3 }}]
    ]);

    var piechart_options = {title:'Pie Chart: Showing number of users of the Marketing survey Assistant Web  Service',
                   width:400,
                   height:300};
    var piechart = new google.visualization.PieChart(document.getElementById('piechart_div'));
    piechart.draw(data, piechart_options);
  }
</script>