Bug 104986 Backgound image uses an absolute path
Currently Chart uses an absolute path to indicate a backgournd image, that may cause the design unusable on other environments. Expected the background image can be definded in multiple ways like in report designer. e.g. URI(absolute path), File(relative path), Embedded Image(Encoded Image Data).
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/render/AxesRenderer.java
}
			logger.log( ILogger.INFORMATION,
					Messages.getString( "info.elapsed.render.time", 
							new Object[]{
								new Long( lTimer )
							}, getRunTimeContext( ).getLocale( ) ) );
			htRenderers.remove( TIMER );
		}
	}
	private final int compare( DataElement de1, DataElement de2 )
			throws ChartException
	{
		if ( de1 == null && de2 == null )
			return IConstants.EQUAL;
		if ( de1 == null || de2 == null )
			return IConstants.SOME_NULL;
		final Class c1 = de1.getClass( );
		final Class c2 = de2.getClass( );
		if ( c1.equals( c2 ) )
		{
			if ( de1 instanceof NumberDataElement )
			{
				return Double.compare( ( (NumberDataElement) de1 ).getValue( ),
						( (NumberDataElement) de2 ).getValue( ) );
			}
			else if ( de1 instanceof DateTimeDataElement )
			{
				final long l1 = ( (DateTimeDataElement) de1 ).getValue( );
				final long l2 = ( (DateTimeDataElement) de1 ).getValue( );
				return ( l1 < l1 ? IConstants.LESS