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/model/attribute/AttributeFactory.java
Location createLocation( );
	/**
	 * Returns a new object of class '<em>Location3 D</em>'.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @return a new object of class '<em>Location3 D</em>'.
	 * @generated
	 */
	Location3D createLocation3D( );
	/**
	 * Returns a new object of class '<em>Marker</em>'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return a new object of class '<em>Marker</em>'.
	 * @generated
	 */
	Marker createMarker( );
	/**
	 * Returns a new object of class '<em>Number Format Specifier</em>'. <!-- begin-user-doc --> <!-- end-user-doc
	 * -->
	 * 
	 * @return a new object of class '<em>Number Format Specifier</em>'.
	 * @generated
	 */
	NumberFormatSpecifier createNumberFormatSpecifier( );
	/**
	 * Returns a new object of class '<em>Palette</em>'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return a new object of class '<em>Palette</em>'.
	 * @generated
	 */