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/AttributePackage.java
* Returns the meta object for enum '{@link org.eclipse.birt.chart.model.attribute.LineDecorator <em>Line Decorator</em>}'.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @return the meta object for enum '<em>Line Decorator</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.LineDecorator
	 * @generated
	 */
	EEnum getLineDecorator( );
	/**
	 * Returns the meta object for enum '{@link org.eclipse.birt.chart.model.attribute.LineStyle <em>Line Style</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for enum '<em>Line Style</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.LineStyle
	 * @generated
	 */
	EEnum getLineStyle( );
	/**
	 * Returns the meta object for enum '{@link org.eclipse.birt.chart.model.attribute.MarkerType <em>Marker Type</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for enum '<em>Marker Type</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.MarkerType
	 * @generated
	 */
	EEnum getMarkerType( );
	/**
	 * Returns the meta object for enum '{@link org.eclipse.birt.chart.model.attribute.Orientation <em>Orientation</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for enum '<em>Orientation</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.Orientation
	 * @generated