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About GanttModel

JavaGantt uses class GanttModel as its model. It is an abstract class derived from eu.beesoft.gaia.swing.TreeTableModel. Here are the methods required to implementation:

• TimelineObject createObject (TimelineObject, int, UndoStep) - creates a new domain object and adds it as child to parent (you don't need to care about treetable nodes). Register all modified objects to undo before any change occurs.
• boolean deleteObject (TimelineObject, UndoStep) - removes given object from its parent on domain objects level (you don't need to care about treetable nodes). Register object, its parent and all modified objects to undo before any change occurs.
• boolean moveObject (TimelineObject, TimelineObject, int, UndoStep) - moves given object on domain objects level (you don't need to care about treetable nodes). Register all modified objects to undo before any change occurs.

The methods above are designed to manipulate with objects on the domain objects level. You don't need to work with treetable nodes.

Here is the implementation of these methods from our demo application:

	@Override
	public boolean moveObject (TimelineObject object,
	        TimelineObject newContainer, int newIndex, UndoStep undo) {
		Task task = (Task) object;
		Task supertask = (Task) newContainer;
		undo.registerObject (task);
		undo.registerObject (supertask);
		Task oldSupertask = task.getSupertask ();
		if (supertask != oldSupertask) {
			if (oldSupertask != null) {
				undo.registerObject (oldSupertask);
				oldSupertask.removeSubtask (task);
			}
			supertask.addSubtask (task);
		}
		supertask.shiftSubtask (task, newIndex);
		return true;
	}



	@Override
	public boolean deleteObject (TimelineObject what, UndoStep undo) {
		Task task = (Task) what;
		Task parent = task.getSupertask ();
		undo.registerObject (parent);
		undo.registerObject (task);
		parent.removeSubtask (task);
		return true;
	}



	@Override
	public TimelineObject createObject (TimelineObject parent, int index,
	        UndoStep undo) {
		undo.registerObject (parent);
		Task parentTask = (Task) parent;
		Task task = new Task ();
		String id = Gantt.getNextTaskId ();
		task.setTaskId (id);
		task.setName ("Task " + id);
		parentTask.addSubtask (task);
		parentTask.shiftSubtask (task, index);
		return task;
	}

There is an UndoStep object used as argument in these methods. It supports undo / redo operations. You can read more about it in the next chapter.