Bug 193467 URL hyperlink can't work in chart viewer
chart/org.eclipse.birt.chart.viewer/src/org/eclipse/birt/chart/viewer/internal/util/ChartImageManager.java
{
	/**
	 * Flag indicating that if initialize the context.
	 */
	protected static boolean isInitContext = false;
	private static final String IMAGE_FOLDER = "imageTemp"; 
	private static final String IMAGE_NAME_PREFIX = "ChartImage"; 
	/**
	 * Image folder to put the image files
	 */
	public static String imageFolder = null;
	private static List sessionIds = new ArrayList( );
	private static int imageIndex = 0;
	private String sessionId = null;
	private Chart cm = null;
	private String sExtension = null;
	private IDataRowExpressionEvaluator evaluator = null;
	private IStyleProcessor styleProc = null;
	private RunTimeContext rtc = null;
	private IExternalContext externalContext = null;
	private IDeviceRenderer idr = null;
	private String imageMap = null;
	private File imageFile;
	private int dpi = 72;
	public ChartImageManager( String sessionId, Chart chartModel,
			String outputFormat, IDataRowExpressionEvaluator evaluator,