Bug 194549 Memory leak in chart device renderers
After memory analysis for Chart code, it indicates java.awt.Font objects are not garbage collected. Investigating the renderer code, Graphics2D objects in IDisplayServer and IDeviceRenderer are not disposed after chart rendering finished. Need to invoke IDeviceRenderer.dispose() after ChartReportItemPresentationImpl being finished, and dispose all required resources in that method, including IDisplayServer and anything else.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/device/IDisplayServer.java
*/
	Object getObserver( );
	/**
	 * An instance of a text metrics computation class capable of providing text
	 * metric information associated with a given Label to aid in typically
	 * computing the size of rendered text
	 * 
	 * @param la
	 *            The Label instance for which text metrics are being requested
	 * 
	 * @return Text metrics associated with the specified Label instance
	 */
	ITextMetrics getTextMetrics( Label la );
	/**
	 * Provides the locale to display server implementations as needed to
	 * retrieve localized resources for presentation.
	 * 
	 * @return locale
	 * @deprecated use {@link #getULocale()} instead.
	 */
	Locale getLocale( );
	/**
	 * Provides the locale to display server implementations as needed to
	 * retrieve localized resources for presentation.
	 * 
	 * @return ulocale
	 * @since 2.1
	 */
	ULocale getULocale( );
}