Bug 150347 Support binary stream as preview image.
See 144843. We need model to save binary strame as report preview image. Currently, preview image is an external image. Maybe need a type to distinguish preview image type.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/activity/NotificationEvent.java
/**
	 * Event is being sent to the listeners of the object itself.
	 */
	public static final int DIRECT = 0;
	/**
	 * Event is being sent to the descendents of the object. Descendents are
	 * those that extend the target, directly or indirectly.
	 */
	public static final int DESCENDENT = 1;
	/**
	 * Event is being sent to elements that use a style.
	 */
	public static final int STYLE_CLIENT = 2;
	/**
	 * Event is being sent to the contents of the target.
	 */
	public static final int CONTENTS = 3;
	/**
	 * Event is being sent to the elements that use an element.
	 */
	public static final int ELEMENT_CLIENT = 4;
	/**
	 * Event is being sent to the elements that use a structure defined in
	 * report design.
	 */
	public static final int STRUCTURE_CLIENT = 5;
	/**
	 * The design element that changed.
	 */