Customize properties

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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;
  }
  

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);
}