AddRule Class
Domain-Specific Language Tools Reference
AddRule Class

Updated: November 2007

Represents a rule that is called when an object is added to the model.

Namespace:  Microsoft.VisualStudio.Modeling
Assembly:  Microsoft.VisualStudio.Modeling.Sdk (in Microsoft.VisualStudio.Modeling.Sdk.dll)

Visual Basic (Declaration)
Public MustInherit Class AddRule _
    Inherits Rule
Visual Basic (Usage)
Dim instance As AddRule
C#
public abstract class AddRule : Rule
Visual C++
public ref class AddRule abstract : public Rule
JScript
public abstract class AddRule extends Rule

When an object of a specific type is added to the model and you want to do something programmatically, you define a class derived from AddRule.

A RuleOnAttribute attribute placed on the class indicates what type of object the Rule works on and when the rule should fire.

The rule is called when the object of the specified type is added to the model, whether it is added in the UI or programmatically.

In the following example, A Rule is defined that derives from AddRule. This rule sets the position of a Shape when it is added to the diagram.

The RuleOn attribute indicates that the rule should fire when the top level transaction commits.

[RuleOn(typeof(ParentShapeContainsNestedChildShapes), FireTime = TimeToFire.TopLevelCommit)]
public class ShapeAddedToDiagramRule : AddRule
{
  private double offset = 0.25;
  private PointD location = new PointD(0.25, 0.25);

  public override void ElementAdded(ElementAddedEventArgs e)
  {
    Shape shape = null;
    ParentShapeContainsNestedChildShapes nestedLink = e.ModelElement as ParentShapeContainsNestedChildShapes;
    if (nestedLink != null)
    {
      shape = nestedLink.NestedChildShapes as Shape;
    }

    if (shape != null && shape.Diagram != null)
    {
      // Expand the shape and move it to its new position
      shape.IsExpanded = true;
      shape.Location = new PointD(location.X, location.Y + offset);

      // Adjust the height offset for the size of the shape
      // (I'm assuming that the DefaultContainerMargin
      // provides for a decent spacing between the shapes)
      offset += shape.Size.Height + shape.Diagram.DefaultContainerMargin.Height;
    }
  }
}
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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