public class FileEditPart extends AbstractGraphicalEditPart{
        
	public FileEditPart(File file){
		setModel(file);
	}
	
	@Override
	protected IFigure createFigure() {
		FileFigure figure = new FileFigure(((File)getModel()).getName(), null, null);
		
		return figure;
	}

	@Override
	public IFigure getContentPane() {
		return ((FileFigure)getFigure()).getContentPane();
	}

	@Override
	protected List<File> getModelChildren() {	
		if (getModel().isDirectory()){
			return Arrays.asList(getModel().listFiles());
		}
		return new ArrayList<File>();
	}

	public File getModel(){
		return (File)super.getModel();
	}


}

public class RootEditPart extends AbstractGraphicalEditPart {
        //root denotes the directory under which to show the file elements.
	public RootEditPart(String root){
		setModel(root);
	}

	@Override
	protected IFigure createFigure() {
		Figure figure = new FreeformLayer();
		figure.setBorder(new MarginBorder(3));
		figure.setLayoutManager(new FreeformLayout());
		
		return figure;
	}

	@Override
	protected List<File> getModelChildren() {
		List<File> children = Arrays.asList(new File(getModel()).listFiles());
		return children;
	}
	
	@Override
	public String getModel() {
		return (String) super.getModel();
	}
	
}

public class FileEditPartFactory implements EditPartFactory {

	@Override
	public EditPart createEditPart(EditPart context, Object model) {
		if (model instanceof File){
			return new FileEditPart((File)model);
		}else if (model instanceof String){
			return new RootEditPart((String)model);
		}
		return null;
	}

}

public class GEFView extends ViewPart {
	private Shell shell;
	private ScrollingGraphicalViewer viewer;

	@Override
	public void createPartControl(Composite parent) {
		viewer = new ScrollingGraphicalViewer();
		viewer.createControl(parent);
		viewer.getControl().setBackground(ColorConstants.white);
		viewer.setRootEditPart(new ScalableFreeformRootEditPart());		
		viewer.setEditPartFactory(new FileEditPartFactory());
		
		shell = parent.getShell();
		
		shell.getDisplay().asyncExec(new Runnable(){

			@Override
			public void run() {
				String file = new DirectoryDialog(shell).open();
				if (file != null){
					viewer.setContents(file);
				}
			}
		});
	}
	
	@Override
	public void setFocus() {
		
	}

}

getParent().setLayoutConstraint(this, figure, layout);