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.device.extension/src/org/eclipse/birt/chart/device/swing/SwingRendererImpl.java
final Fill flBackground = validateMultipleFill( ore.getBackground( ) );
		if ( isFullTransparent( flBackground ) )
		{
			return;
		}
		final Bounds bo = ore.getBounds( );
		final Ellipse2D.Double e2d = new Ellipse2D.Double( bo.getLeft( ),
				bo.getTop( ),
				bo.getWidth( ),
				bo.getHeight( ) );
		if ( flBackground instanceof ColorDefinition )
		{
			final ColorDefinition cd = (ColorDefinition) flBackground;
			_g2d.setColor( (Color) _ids.getColor( cd ) );
			_g2d.fill( e2d );
		}
		else if ( flBackground instanceof Gradient )
		{
			final Gradient g = (Gradient) flBackground;
			final ColorDefinition cdStart = g.getStartColor( );
			final ColorDefinition cdEnd = g.getEndColor( );
			
			double dAngleInDegrees = g.getDirection( );
			final double dAngleInRadians = ( ( -dAngleInDegrees * Math.PI ) / 180.0 );
			if ( dAngleInDegrees < -90 || dAngleInDegrees > 90 )
			{
				throw new ChartException( ChartDeviceExtensionPlugin.ID,
						ChartException.RENDERING,
						"SwingRendererImpl.exception.gradient.angle",
						new Object[]{