private void handleExportToPNG() {
FileChooser fileChooser = new FileChooser();
fileChooser.setTitle("Export to PNG");
fileChooser.setSelectedExtensionFilter(new FileChooser.ExtensionFilter(
"Portable Network Graphics (PNG)", "png"));
File file = fileChooser.showSaveDialog(this.getScene().getWindow());
if (file != null) {
try {
ExportUtils.writeAsPNG(this.chart, (int) getWidth(),
(int) getHeight(), file);
} catch (IOException ex) {