在Eclipse中确定滚动图形浏览器可见区域的大小

我正在尝试使用eclipsegef创建一个简单的应用程序,它在ScrollingGraphicalViewer中显示一个图表。在启动时,我希望图表在查看器中居中(想象一个星形布局,其中星形的中心位于视图的中心)。

以下是我认为相关的代码部分:

我的观点:

public class View extends ViewPart {
    public static final String ID = "GEFProofOfConcept.view";

...         

    public void createPartControl(Composite parent) {
        viewer.createControl(parent);

        viewer.setRootEditPart(rootEditPart);
        viewer.setEditPartFactory(editPartFactory);

        viewer.setContents(DummyModelCreator.generateModel());          
    }

编辑零件代码:

@Override
protected void refreshVisuals() {
    Project project = (Project) getModel();

    // This is where the actual drawing is done,
    // Simply a rectangle with text
    Rectangle bounds = new Rectangle(50, 50, 75, 50);
    getFigure().setBounds(bounds);
    Label label = new Label(project.getName());
    projectFont = new Font(null, "Arial", 6, SWT.NORMAL);
    label.setFont(projectFont);
    label.setTextAlignment(PositionConstants.CENTER);
    label.setBounds(bounds.crop(IFigure.NO_INSETS));

    getFigure().add(label);

    setLocation();
}

private void setLocation() {
    Project project = (Project) getModel();

    if (project.isRoot()) {
        // Place in centre of the layout
        Point centrePoint = new Point(0, 0); // This is where I need the center of the view
        getFigure().setLocation(centrePoint);
    } else {
        ...
    }       
}

以及上述编辑部分的父级:

public class ProjectDependencyModelEditPart extends AbstractGraphicalEditPart {

@Override
protected IFigure createFigure() {
    Figure f = new FreeformLayer();
    f.setLayoutManager(new XYLayout());

    return f;
}
...

这个问题的替代解决方案也很受欢迎,我当然是一个GEF(和Eclipse)新手。