In this tutorial we will see how to add a label to a diagram edge.

The diagram editor will allow to add Objects linked to other Objects. Each link will have an identifier displayed through a dedicated label.

This tutorial has been built with :

• Eclipse 3.5.1
• Graphical Modeling Framework SDK 2.2.1
• Eclipse Modeling Framework 2.5.0

• Create a new GMF project named LinkedObjects
• Create a new java package named jfb.examples.gmf.linkedobjects
• Create theses java interfaces :
  • Our diagram contains objects :

package jfb.examples.gmf.linkedobjects;
 
import org.eclipse.emf.common.util.EList;
import org.eclipse.emf.ecore.EObject;
 
/**
 * @model
 */
public interface Diagram extends EObject {
 
	/**
	 * @model containment="true"
	 */
	public EList<Object> getObjects();
 
}

• Each object has a name an contains object links :

package jfb.examples.gmf.linkedobjects;
 
import org.eclipse.emf.common.util.EList;
import org.eclipse.emf.ecore.EObject;
 
/**
 * @model
 */
public interface Object extends EObject {
 
	/**
	 * @model
	 */
	public String getName();
 
	/**
	 * @model containment="true"
	 */
	public EList<Link> getLinks();
 
}

• Each link has an id and a reference to the target object :

package jfb.examples.gmf.linkedobjects;
 
import org.eclipse.emf.ecore.EObject;
 
/**
 * @model
 */
public interface Link extends EObject {
 
	/**
	 * @model
	 */
	public String getId();
 
	/**
	 * @model
	 */
	public Object getTargetObject();
 
}

• Create a new EMF Generator Model named linkedobjects.genmodel in the model folder (right click on the LinkedObjects project, select New, choose EMF Generator Model)
• Select Annotated Java and click next
• Select the package that you have just created above and click finish
• Optionnaly, you can generate a visual representation of the model by right clicking on the linkedobjects.ecore file that has been generated above and by selecting Initialize ecore_diagram diagram file
• You should get this :

• In the Dashboard view :
  • select the Domain Gen Model file (linkedobjects.genmodel)
  • select the Domain Model file (linkedobjects.ecore)
• Open the linkedobjects.genmodel file
• Right click on the root element of the diagram and select Generate Model Code
• Right click on the root element of the diagram and select Generate Edit Code
• Right click on the root element of the diagram and select Generate Editor Code

• Click on the derive label on the left of the Tooling Def Model rectangle of the Dashboard view
• Choose linkedobjects.gmftool as file name and click Next
• Select the Diagram class as Diagram Element and click Next
• In the Node column, check only Object
• In the Links column, check only Link
• You should have :

• Click on the derive label on the left of the Graphical Def Model rectangle of the Dashboard view
• Choose linkedobjects.gmfgraph as file name and click Next
• Select the Diagram class as Diagram Element and click Next
• In the Node column, check only Object
• In the Links column, check only Link
• In the Label column, check : Object.name and Link.id
• You should have :

• Click Finish

• Click on the combine label on the left of the Mapping Model rectangle of the Dashboard view
• Choose linkedobjects.gmfmap as file name and click Next
• Select the Diagram class as Diagram Element and click Next
• In the Select Diagram Palette wizard page, just click next
• In the Select Diagram Canvas wizard page, just click next
• In the Mapping wizard page you should have :

• Click Finish
• Open the linkedobjects.gmfmap file generated above
• Select the Node Mapping <Object/Object> and correct the Tool in the property view (select Creation Tool Object instead of Creation Tool Link)
• Select the Link Mapping <Link{Link.targetObject:Object}/Link> and :
  • correct the Tool in the property view (select Creation Tool Link instead of Creation Tool Object)
  • select the Diagram Label LinkId for the Diagram Label property in the properties view
• Save the file

• Click on the transform label above the Diagram Editor Gen model rectangle of the Dashboard view
• Click on the Generate diagram editor label in the Diagram Editor Gen model rectangle of the Dashboard view

At this point, when running the diagram editor, you should be able to get something like this :

If you want to change the position of your label, you may add an Alignment Facet under the Diagram Label LinkId of the linkedobjects.gmfgraph file and select BEGINNING, END or CENTER.

For example, with an END value, we get this (after having re-transformed the Mapping model into the Diagram Editor Gen Model and having re-generated the diagram editor :

You may also need to change the default offset of the diagram. In the example above, the labels are far from the edge. To correct it, add an Label Offset Facet under the Diagram Label LinkId of the linkedobjects.gmfgraph file and change the x and y values if required.

For example, by leaving x and y to 0, we get this result (do not forget to re-generate the Diagram Editor Gen Model and the diagram editor) :

I hope that this material will be helpful for you. If you want to support it, your help is welcome :