/// <summary>
/// Called during view fixup to ask the parent whether a shape should be created for the given child element.
/// </summary>
/// <remarks>
/// Always return true, since we assume there is only one diagram per model file for DSL scenarios.
/// </remarks>
protected override bool ShouldAddShapeForElement(ModelElement element)
{
ModelElement parent = null;
// for attributes and enum values, the we should add the shape if its parent is on the diagram
if (element is ModelAttribute modelAttribute)
{
parent = modelAttribute.ModelClass;
}
if (element is ModelEnumValue enumValue)
{
parent = enumValue.Enum;
}
bool result =
ForceAddShape || // we've made the decision somewhere else that this shape should be added
IsDroppingExternal || // we're dropping a file from Solution Explorer or File Explorer
base.ShouldAddShapeForElement(element) || // the built-in rules say to do this
DisplayedElements.Contains(element) || // the serialized diagram has this element present (other rules should prevent duplication)
(parent != null && DisplayedElements.Contains(parent)) || // the element's parent is on this diagram
(element is ElementLink link && link.LinkedElements.All(linkedElement => DisplayedElements.Contains(linkedElement))); // adding a link and both of the linkk's end nodes are in this diagram
return(result);
}
private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.Action == NotifyCollectionChangedAction.Add)
{
DisplayedElements.AddRange(e.NewItems.OfType <DisplayedCell>());
}
if (e.Action == NotifyCollectionChangedAction.Remove)
{
foreach (DisplayedCell element in e.OldItems)
{
DisplayedElements.Remove(element);
}
}
if (e.Action == NotifyCollectionChangedAction.Reset)
{
DisplayedElements.Clear();
}
}