[news.eclipse.modeling.gmf] Re: EditPolicyProvider question

[Hallvard Trætteberg <hal@xxxxxxxxxxx>]

On Mon, 11 Sep 2006 15:23:20 -0400, "Cherie Revells (Mahoney)"
<cmahoney@xxxxxxxxxx> wrote:

>Hao Zhang,
>
>All you need to do, is write the provides() method as you would in any 
>other service, describing the type of editpart you provide for (or 
>element of the editpart).  Make sure you are specific here so as not to 
>have your editpolicy installed on non-applicable editparts.
>
>Then you just need to install your editpolicy on the editpart in the 	 
>createEditPolicies() method.
>
>e.g. editPart.installEditPolicy(THE_ROLE, new TheEditPolicy());
>
>I hope this helps.

I'll add some detail, here's code for a
PropertyHandlerEditPolicyProvider class, that installs a
PropertyHandlerEditPolicy for the
EditPolicyRoles.PROPERTY_HANDLER_ROLE role on edit parts of the types
GateEditPart and AbstractVariableEditPart.

public class PropertyHandlerEditPolicyProvider implements
		IEditPolicyProvider {

	public void createEditPolicies(EditPart editPart) {

editPart.installEditPolicy(EditPolicyRoles.PROPERTY_HANDLER_ROLE,
				new PropertyHandlerEditPolicy());
	}

	public boolean provides(IOperation operation) {
		if (operation instanceof CreateEditPoliciesOperation)
{
			EditPart editPart =
((CreateEditPoliciesOperation)operation).getEditPart();
			if (editPart instanceof GateEditPart ||
					editPart instanceof
AbstractVariableEditPart
					)
				return true;
		}
		return false;
	}

	public void addProviderChangeListener(IProviderChangeListener
listener) {
	}
	public void
removeProviderChangeListener(IProviderChangeListener listener) {
	}
}

Remember also to declare the PropertyHandlerEditPolicyProvider class
in plugin.xml, as follows:

      	<editPolicyProvider
class="no.hal.diamodl.diagram.custom.providers.PropertyHandlerEditPolicyProvider">
         	<Priority name="Lowest"/>
         	<object id="GateEditPart"
class="no.hal.diamodl.diagram.edit.parts.GateEditPart(no.hal.diamodl.gmf.diagram)"/>
         	<object id="VariableEditPart"
class="no.hal.diamodl.diagram.edit.abstractparts.AbstractVariableEditPart(no.hal.diamodl.gmf.diagram)"/>
         	<context
         		editparts="GateEditPart,VariableEditPart"
         	/>
        </editPolicyProvider>

Note how the object elements declares IDs for the EditPart classes
(the project/plugin name is within the parenthesis), and how the
context element refers to these IDs.

Hallvard

>
>- Cherie
>
>
>Hao Zhang wrote:
>> Hi,
>> Is there any editpolicyprovider snippet except the one in GMF Developer 
>> Guide, in which I couldn't find the source of 
>> TraceDiagramEditPolicyProvider. In fact, I found no implementation of 
>> IEditPolicyProvider except EditPolicyService, so I wonder how to 
>> implement the TraceDiagramEditPolicyProvider above.
>>