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
int LINE_STYLE = 54;
	/**
	 * The meta object id for the '{@link org.eclipse.birt.chart.model.attribute.MarkerType <em>Marker Type</em>}' enum.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @see org.eclipse.birt.chart.model.attribute.MarkerType
	 * @see org.eclipse.birt.chart.model.attribute.impl.AttributePackageImpl#getMarkerType()
	 * @generated
	 */
	int MARKER_TYPE = 55;
	/**
	 * The meta object id for the '{@link org.eclipse.birt.chart.model.attribute.Orientation <em>Orientation</em>}' enum.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @see org.eclipse.birt.chart.model.attribute.Orientation
	 * @see org.eclipse.birt.chart.model.attribute.impl.AttributePackageImpl#getOrientation()
	 * @generated
	 */
	int ORIENTATION = 56;
	/**
	 * The meta object id for the '{@link org.eclipse.birt.chart.model.attribute.Position <em>Position</em>}' enum.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @see org.eclipse.birt.chart.model.attribute.Position
	 * @see org.eclipse.birt.chart.model.attribute.impl.AttributePackageImpl#getPosition()
	 * @generated
	 */
	int POSITION = 57;
	/**
	 * The meta object id for the '{@link org.eclipse.birt.chart.model.attribute.RiserType <em>Riser Type</em>}' enum.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @see org.eclipse.birt.chart.model.attribute.RiserType
	 * @see org.eclipse.birt.chart.model.attribute.impl.AttributePackageImpl#getRiserType()