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
* @generated
	 */
	int MARKER_TYPE_OBJECT = 89;
	/**
	 * The meta object id for the '<em>Orientation Object</em>' data type.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @see org.eclipse.birt.chart.model.attribute.Orientation
	 * @see org.eclipse.birt.chart.model.attribute.impl.AttributePackageImpl#getOrientationObject()
	 * @generated
	 */
	int ORIENTATION_OBJECT = 90;
	/**
	 * The meta object id for the '<em>Percentage</em>' data type. <!--
	 * begin-user-doc --> <!-- end-user-doc -->
	 * 
	 * @see org.eclipse.birt.chart.model.attribute.impl.AttributePackageImpl#getPercentage()
	 * @generated
	 */
	int PERCENTAGE = 91;
	/**
	 * The meta object id for the '<em>Percentage Object</em>' data type.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @see java.lang.Double
	 * @see org.eclipse.birt.chart.model.attribute.impl.AttributePackageImpl#getPercentageObject()
	 * @generated
	 */
	int PERCENTAGE_OBJECT = 92;
	/**
	 * The meta object id for the '<em>Position Object</em>' data type. <!--
	 * begin-user-doc --> <!-- end-user-doc -->