How to export the data label template with a Angular Pie Charts in the PNG format?

Description

This article shows how to export the datalabel template with Angular Pie Charts in the PNG format.

Solution

The data label template in the Angular Pie Charts cannot be exported to an image because it is intended to render any items in the charts component, such as text, images, or custom HTML elements. Since the chart is an SVG-based component, the data label template can be rendered as a foreignObject element at the application level.

You can create a foreignObject element for each data label template and add it to the chart component’s SVG element. Then, to allow image and PDF export, you can draw this SVG element in an HTML canvas element. Using the HTML image element, this canvas element can be transformed into an image. This image element is now converted to a PNG or JPEG image for export, or it can be inserted into a PDF document using Syncfusion’s ej2-pdf-export library.

Code Snippet

I hope you enjoyed learning

In the following code, the above process is carried out in the exportPie method

public exportPie() {
       var label = [];
       var labels;
       var padding;
       var width;
       var height;
       var svg = document.getElementById("container_svg");
       var clone = svg.cloneNode(true);
       var series = document.getElementById("container_SeriesCollection");
       for (var k = 0; k < series.childElementCount; k++) {
           label = document.getElementById("container").querySelectorAll('[id= ' + 'container_Series_' + k + '_DataLabelCollections');
           if (label.length >= 1) {
               for (var j = 0; j < label[0].children.length; j++) {
                   labels = label[0].children[j];
                   var foreign = document.createElementNS("http://www.w3.org/2000/svg", "foreignObject");
                   foreign.setAttribute("width", labels.getBoundingClientRect().width);
                   foreign.setAttribute("height", (labels.getBoundingClientRect().height));
                   padding = labels.getBoundingClientRect().height;
                   if (series.childElementCount > 1) {
                       foreign.setAttribute("x", parseFloat(labels.style.left).toString());
                   } else {
                       foreign.setAttribute("x", (parseFloat(labels.style.left) - padding).toString());
                   }
                   foreign.setAttribute("y", labels.style.top);
                   var style = labels.children[0].getAttribute("style");
                   foreign.setAttribute('style', style);
                   foreign.innerHTML = labels.innerHTML;
                   width = parseFloat(svg.getAttribute("width"));
                   height = parseFloat(svg.getAttribute("height"));
                   clone.setAttribute("width", width.toString());
                   clone.setAttribute("width", width.toString());
                   clone.setAttribute("height", height.toString());
                   clone.appendChild(foreign);
               }
           }            
       }
       var svgData = new XMLSerializer().serializeToString(clone);
       var canvas = document.createElement("canvas");
       document.body.appendChild(canvas);
       var svgSize = clone.getBoundingClientRect();
       canvas.width = parseFloat(clone.getAttribute("width"));
       canvas.height = parseFloat(clone.getAttribute("height"));
       canvas.style.backgroundColor = "white";
       var ctx = canvas.getContext("2d");
       var image = new Image();
       image.setAttribute("src", "data:image/svg+xml;base64," + btoa(svgData));
       image.onload = function () {
           ctx.drawImage(image, 0, 0);
           var imagedata  = canvas.toDataURL("image/png");
           var anchor = document.createElement("a");
           anchor.download = "Chart.png";
           anchor.href = imagedata;
           document.body.appendChild(anchor);
           anchor.click();
           canvas.remove();
       };
   };

The following image illustrates the output of the above code.

View Sample in Stackblitz

Conclusion

I hope you enjoyed learning how to export the data label template with an Angular Pie Chart in the PNG format

You can refer to our Angular Charts feature tour page to learn about its other features and documentation, and how to quickly get started for configuration specifications. You can also explore our Angular Charts example to understand how to create and visualize data.

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