amCharts 4 - 使用 .export() 在导出的图像中包含标题和水印

如何解决amCharts 4 - 使用 .export() 在导出的图像中包含标题和水印

如何使用 .export() 在导出的图像中包含图像标题和水印？

这个例子展示了一个带有 .export() 的函数

https://github.com/armink/CmBacktrace

// Create chart instance
var chart = am4core.create("chartdiv",am4charts.XYChart);

// Add data
chart.data = [{
  "category": "Research & Development","value": 3.5
},{
  "category": "Marketing","value": 6
},{
  "category": "distribution","value": 4.2
}];

// Create axes
let categoryAxis = chart.xAxes.push(new am4charts.CategoryAxis());
categoryAxis.datafields.category = "category";

let valueAxis = chart.yAxes.push(new am4charts.ValueAxis());

// Create series
var series = chart.series.push(new am4charts.ColumnSeries());
series.datafields.valueY = "value";
series.datafields.categoryX = "category";
series.name

// Custom export function
function exportPNG() {
  chart.exporting.title = "myTitle"; /* not working */
  chart.exporting.export("png");
}

var options = chart.exporting.getFormatOptions("png");
options.keepTainted = true;
chart.exporting.setFormatOptions("png",options);

我还需要一个水印（仅在导出的图像中）：

var watermark = chartPie.createChild(am4core.Label);
watermark.text = "Source: [bold]www.domain.com[/]";
watermark.align = "right";
watermark.fillOpacity = 0.5;
watermark.marginRight = 10;
watermark.marginBottom = 10;