private CancellationTokenSource _cancellationTokenSource;
private async void ExportAsync(PageReport report, IRenderingExtension renderingExtension, FileStreamProvider outputProvider, NameValueCollection settings)
{
	_cancellationTokenSource = new CancellationTokenSource();
	cancelButton.Text = "Cancel";
	await Task.Run(() =>
	{
		try
		{
			report.Document.Render(renderingExtension, outputProvider, settings, false, false, _cancellationTokenSource.Token);
		}
		catch (OperationCanceledException)
		{
		}
	});
	if (_cancellationTokenSource.IsCancellationRequested)
	MessageBox.Show("Export was cancelled", "Export", MessageBoxButtons.OK, MessageBoxIcon.Information);
	_cancellationTokenSource.Dispose();
}
private void cancelExport(object sender, EventArgs e)
{
	_cancellationTokenSource?.Cancel();
}