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.device.extension/src/org/eclipse/birt/chart/device/swing/SwingRendererImpl.java
{
				throw new ChartException( ChartDeviceExtensionPlugin.ID,
						ChartException.RENDERING,
						muex );
			}
			final Shape shClip = _g2d.getClip( );
			Area ar1 = new Area( shClip );
			Area ar2 = new Area( r2d );
			ar2.intersect( ar1 );
			_g2d.setClip( ar2 );
			final Size szImage = _ids.getSize( img );
			int iXRepeat = (int) ( Math.ceil( r2d.width / szImage.getWidth( ) ) );
			int iYRepeat = (int) ( Math.ceil( r2d.height / szImage.getHeight( ) ) );
			ImageObserver io = (ImageObserver) _ids.getObserver( );
			for ( int i = 0; i < iXRepeat; i++ )
			{
				for ( int j = 0; j < iYRepeat; j++ )
				{
					_g2d.drawImage( img,
							(int) ( r2d.x + i * szImage.getWidth( ) ),
							(int) ( r2d.y + j * szImage.getHeight( ) ),
							io );
				}
			}
			
			_g2d.setClip( shClip ); 
		}
	}
	/**
	 * In SWING, polygons are defined with 'int' co-ordinates. There is no