Center a DSL shape on diagram screen

Question

First, sorry my english.

I'm developing a DSL. In the main window I have two panels: a list of shapes and the diagram itself. I would like, when clicking on an item in the list, to center its shape on the screen (diagram panel).

I don't want to move the shape to the center of the diagram. I want to scroll the diagram to center the shape.

Another way to explain: When a validation error occurs (Error List window on bottom), and when clicking on the error, it centers the invalid shape on the screen, right? That's what I want.

Start point:

private void symbolsListBox_SelectedIndexChanged(object sender, EventArgs e)
{
    var listBox = sender as ListBox;
    var symbol = listBox.SelectedItem as Symbol;
    var compartment = PresentationViewsSubject.GetPresentation(symbol)
        .FirstOrDefault() as SymbolCompartmentShape;
    var diagram = docView.CurrentDiagram;

    //Next step, center the shape
    //How? God please help me!!!
}

Image example is always better!! So...

HERE, AN EXAMPLE IMAGE OF THAT I WANT

HERE, AN EXAMPLE IMAGE OF THE EXPECTED RESULT

Answer 1

What you can do is locate the shape in the diagram and select it. The diagram will automatically make it visible if necessary.

Here's the code I use for that. Note that this starts from the ModelElement (not the shape).

valueListAssociation.LocateInDiagram();

Now the extension methods:

public static bool LocateInDiagram(this ModelElement element)
{
    // Validation

    SmartGuard.NotNull(() => element, element);

    // Get the diagram view

    DiagramView diagramView = element.GetActiveDiagramView();
    if (diagramView != null)
    {
        // Select it

        return diagramView.SelectModelElement(element);
    }

    // Default result

    return false;
}

public static DiagramView GetActiveDiagramView(this ModelElement element)
{
    // Validation

    SmartGuard.NotNull(() => element, element);

    // Get the shape that corresponds to this model element

    ShapeElement shapeElement = element.GetShapeElement();
    if (shapeElement != null)
    {
        // Result

        return shapeElement.GetActiveDiagramView();
    }

    // Default result

    return null;
}

public static ShapeElement GetShapeElement(this ModelElement element)
{
    // Validation

    SmartGuard.NotNull(() => element, element);

    // Get the first shape
    // If the model element is in a compartment the result will be null

    ShapeElement shape = element.GetFirstShapeElement();
    if (shape == null)
    {
        // If the element is in a compartment, try to get the parent model element to select that

        ModelElement parentElement = element.GetCompartmentElementFirstParentElement();
        if (parentElement != null)
        {
            shape = parentElement.GetFirstShapeElement();
        }
    }

    // Result

    return shape;
}

private static ShapeElement GetFirstShapeElement(this ModelElement element)
{
    // Presentation elements

    LinkedElementCollection<PresentationElement> presentations = PresentationViewsSubject.GetPresentation(element);
    foreach (PresentationElement presentation in presentations)
    {
        ShapeElement shapeElement = presentation as ShapeElement;
        if (shapeElement != null)
        {
            return shapeElement;
        }
    }

    // Default result

    return null;
}

private static ModelElement GetCompartmentElementFirstParentElement(this ModelElement modelElement)
{
    // Get the domain class associated with model element.

    DomainClassInfo domainClass = modelElement.GetDomainClass();
    if (domainClass != null)
    {
        // A element is only considered to be in a compartment if it participates in only 1 embedding relationship
        // This might be wrong for some models

        if (domainClass.AllEmbeddedByDomainRoles.Count == 1)
        {
            DomainRoleInfo roleInfo = domainClass.AllEmbeddedByDomainRoles[0];
            if (roleInfo != null)
            {
                // Get a collection of all the links to this model element
                // Since this is in a compartment there should be at least one
                // There can be only one.

                ReadOnlyCollection<ElementLink> links = roleInfo.GetElementLinks(modelElement);
                if (links.Count == 1)
                {
                    // Get the model element participating in the link that isn't the current one
                    // That will be the parent
                    // Probably there is a better way to achieve the same result

                    foreach (ModelElement linkedElement in links[0].LinkedElements)
                    {
                        if (!modelElement.Equals(linkedElement))
                        {
                            return linkedElement;
                        }
                    }
                }
            }
        }
    }

    // Default result

    return null;
}

public static DiagramView GetActiveDiagramView(this ShapeElement shape)
{
    // Validation

    SmartGuard.NotNull(() => shape, shape);

    // Result

    if (shape.Diagram != null)
    {
        return shape.Diagram.ActiveDiagramView;
    }

    // Default result

    return null;
}

public static bool SelectModelElement(this DiagramView diagramView, ModelElement modelElement, bool ensureVisible)
{
    // Validation

    SmartGuard.NotNull(() => diagramView, diagramView);
    SmartGuard.NotNull(() => modelElement, modelElement);

    // Get the shape element that corresponds to the model element

    ShapeElement shapeElement = modelElement.GetPresentation<ShapeElement>();
    if (shapeElement != null)
    {
        // Make sure the shape element is visible (because connectors can be hidden)

        if (!shapeElement.IsVisible)
        {
            shapeElement.Show();
        }

        // Create a diagram item for this shape element and select it

        diagramView.SelectDiagramItem(new DiagramItem(shapeElement), ensureVisible);
        return true;
    }

    // If the model element does not have a shape, try to cast it IModelElementCompartmented

    IModelElementCompartmented compartmentedModelElement = modelElement as IModelElementCompartmented;
    if (compartmentedModelElement != null)
    {
        // Get the parent

        IModelElementWithCompartments parentModelElement = compartmentedModelElement.ParentModelElement;
        if (parentModelElement != null)
        {
            // Get the compartment that stores the model element

            ElementListCompartment compartment = parentModelElement.GetCompartment(compartmentedModelElement.CompartmentName);
            if (compartment == null)
            {
                throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, Properties.Resources.RES_Error_CannotFindCompartment, compartmentedModelElement.CompartmentName));
            }

            // Expand the compartment?

            if (!compartment.IsExpanded)
            {
                using (Transaction trans = modelElement.Store.TransactionManager.BeginTransaction("IsExpanded"))
                {
                    compartment.IsExpanded = true;
                    trans.Commit();
                }
            }

            // Find the model element in the compartment

            int index = compartment.Items.IndexOf(modelElement);
            if (index >= 0)
            {
                // Create a diagram item and select it

                diagramView.SelectDiagramItem(new DiagramItem(compartment, compartment.ListField, new ListItemSubField(index)), ensureVisible);

                // Result OK

                return true;
            }
        }
    }

    // Default result

    return false;
}

Notice that this last method has a "trick" to deal with shapes that have compartments (IModelElementCompartmented). You can omit this part if your shapes don't have compartments.