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
* @return the meta object for enum '<em>Action Type</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.ActionType
	 * @generated
	 */
	EEnum getActionType( );
	/**
	 * Returns the meta object for enum '{@link org.eclipse.birt.chart.model.attribute.Anchor <em>Anchor</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for enum '<em>Anchor</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.Anchor
	 * @generated
	 */
	EEnum getAnchor( );
	/**
	 * Returns the meta object for enum '{@link org.eclipse.birt.chart.model.attribute.AngleType <em>Angle Type</em>}'.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @return the meta object for enum '<em>Angle Type</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.AngleType
	 * @generated
	 */
	EEnum getAngleType( );
	/**
	 * Returns the meta object for enum '{@link org.eclipse.birt.chart.model.attribute.ChartType <em>Chart Type</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for enum '<em>Chart Type</em>'.
	 * @see org.eclipse.birt.chart.model.attribute.ChartType
	 * @generated
	 */
	EEnum getChartType( );