Advanced Uses
Server-Side Rendering and Exporting
In addition to using charts in Vaadin UIs, you may also need to provide them as images or in downloadable documents. Vaadin Charts can be rendered on the server-side using a headless JavaScript execution environment, such as PhantomJS.
Vaadin Charts supports a HighCharts remote export service, but the SVG Generator based on PhantomJS is almost as easy to use and allows much more powerful uses.
Using a Remote Export Service
Vaadin Charts has a simple built-in export functionality that does the export in a remote export server. Vaadin Charts provides a default export service, but you can also configure your own.
You can enable the built-in export function by setting setExporting(true) in the chart configuration.
chart.getConfiguration().setExporting(true);To configure it further, you can provide a Exporting object with custom settings.
// Create the export configuration
Exporting exporting = new Exporting(true);
// Customize the file name of the download file
exporting.setFilename("mychartfile");
// Use the exporting configuration in the chart
chart.getConfiguration().setExporting(exporting);The functionality uses a HighCharts export service by default. To use your own, you need to set up one and then configure it in the exporting configuration as follows:
exporting.setUrl("https://my.own.server.com");Using the SVG Generator
The SVGGenerator in Vaadin Charts provides an advanced way to render the Chart into SVG format on the server-side. SVG is well supported by many applications, can be converted to virtually any other graphics format, and can be passed to PDF report generators.
The generator uses PhantomJS to render the chart on the server-side. You need to install it from phantomjs.org. After installation, PhantomJS should be in your system path. If not, you can set the phantom.exec system property for the JRE to point to the PhantomJS binary.
To generate the SVG image content as a string (it’s XML), simply call the generate() method in the SVGGenerator singleton and pass it the chart configuration.
String svg = SVGGenerator.getInstance()
.generate(chart.getConfiguration());You can then use the SVG image as you like, for example, for download from a StreamResource, or include it in a HTML, PDF, or other document. You can use SVG tools such as the Batik or iText libraries to generate documents. For a complete example, you can check out the Charts Export Demo from the Subversion repository at https://github.com/vaadin/charts/tree/master/chart-export-demo.