= Customize properties =

[wiki:gmf:gmf <back]

This section is about customizing properties on the basis of an example.

What I want: My element A has a property of type B. B is something like a file so it has a property "path" of type String. I want a file chooser to choose the file. The path of the file should be stored in the path property of the property B of element A.

What to do:

  * Write a class like the following. This is the file chooser itself.
{{{
public class FileChooserCellEditor extends DialogCellEditor {

   private Composite parent;
	
   public FileChooserCellEditor(Composite parent) {
	super(parent);
	this.parent = parent;
   }

   protected Object openDialogBox(Control cellEditorWindow) {
	FileDialog dialog = new FileDialog(parent.getShell(), SWT.OPEN);
	return dialog.open();
   }
}

}}}

  * Write a property descriptor for all your properties:
{{{
public class ExhibitionPropertyDescriptor extends
		EMFCompositeSourcePropertyDescriptor {

   IItemPropertyDescriptor itemPropertyDescriptor;
	
   public ExhibitionPropertyDescriptor(Object object,
		IItemPropertyDescriptor itemPropertyDescriptor, String category) {
	super(object, itemPropertyDescriptor, category);
	this.itemPropertyDescriptor = itemPropertyDescriptor;
   }

   /* here you can instanciate whatever you want to be 
      opened when the user clicks on the button in the property field
   */
   protected CellEditor doCreateEditor(Composite composite) {
	if (itemPropertyDescriptor instanceof ImagePropertyDescriptor) {
	   return new FileChooserCellEditor(composite);
	}
	return super.doCreateEditor(composite);
   }
}
}}}

  * Change your XXXPropertySection in the package "sheet" as follows:
{{{
/**
 * @generated NOT
 */
public IPropertySource getPropertySource(Object object) {
   if (object instanceof IPropertySource) {
	return (IPropertySource) object;
   }
   AdapterFactory af = getAdapterFactory(object);
   if (af != null) {
	IItemPropertySource ips = (IItemPropertySource) af.adapt(object,
				IItemPropertySource.class);
	if (ips != null) {
	   return new EMFCompositePropertySource(object, ips,
					null) {
		protected IPropertyDescriptor newPropertyDescriptor(
			IItemPropertyDescriptor itemPropertyDescriptor) {
			return new ExhibitionPropertyDescriptor(object,
				itemPropertyDescriptor, getCategory());
		}
	   };
	}
   }
   if (object instanceof IAdaptable) {
	return (IPropertySource) ((IAdaptable) object)
		.getAdapter(IPropertySource.class);
	}
   return null;
}
}}}

  * Write a new ItemPropertyDescriptor for B:
{{{

public class ImagePropertyDescriptor extends ItemPropertyDescriptor {
	
	EStructuralFeature feature;
	
	public ImagePropertyDescriptor(AdapterFactory adapterFactory,
			ResourceLocator resourceLocator, String displayName,
			String description, EStructuralFeature feature, boolean isSettable,
			boolean multiLine, boolean sortChoices, Object staticImage,
			String category, String[] filterFlags) {
		super(adapterFactory, resourceLocator, displayName, description, feature,
				isSettable, multiLine, sortChoices, staticImage, category, filterFlags);
		this.feature = feature;
	}

        // here you decide what data of B is displayed in property view for A
	@Override
	protected Object getValue(EObject object, EStructuralFeature feature) {
		Object propertyObject = object.eGet(feature);
		if (propertyObject == null) return "";
		if (propertyObject instanceof Image)
		{
			String path = ((Image) propertyObject).getImagePath();
			return path;
		}
		return super.getValue(object, feature);
	}

        // this is how to handle the input from the file chooser
	@Override
	public void setPropertyValue(Object object, Object value) {
		if (object instanceof EObject)
		{
			EObject eobject = (EObject) object;
			Image backgroundImage = ExhibitionFactory.eINSTANCE.createImage();
			backgroundImage.setImagePath(value.toString());
			eobject.eSet(feature, backgroundImage);
			return;
		}
		super.setPropertyValue(object, value);
	}
	
	
}
}}}

  * the last thing is that you add the new property descriptor in you AItemProvider Class:
{{{
/**
 * This returns the property descriptors for the adapted class.
 * <!-- begin-user-doc -->
 * <!-- end-user-doc -->
 * @generated NOT
 */
@Override
public List<IItemPropertyDescriptor> getPropertyDescriptors(Object object) {
	if (itemPropertyDescriptors == null) {
		super.getPropertyDescriptors(object);

		addTitlePropertyDescriptor(object);
		addDescriptionPropertyDescriptor(object);
                // --------------- this is new -----------
		addBackgroundImageDescriptor(object);
                // ---------------------------------------
	}
	return itemPropertyDescriptors;
}
}}} 
[[BR]]
and this is the new method:
{{{
protected void addBackgroundImageDescriptor(Object object)
{
   IItemPropertyDescriptor imagePropertyDescriptor =
	new ImagePropertyDescriptor(((ComposeableAdapterFactory)adapterFactory).getRootAdapterFactory(),
	   getResourceLocator(),
	   getString("_UI_Scene_backgroundImage_feature"),
	   getString("_UI_PropertyDescriptor_description", "_UI_Scene_backgroundImage_feature", "_UI_Scene_type"),
	   ExhibitionPackage.Literals.SCENE__BACKGROUND_IMAGE,
	   true,
	   false,
	   false,
	   ItemPropertyDescriptor.GENERIC_VALUE_IMAGE,
	   null,
  	   null);
   itemPropertyDescriptors.add(imagePropertyDescriptor);
}
}}}