diagramlayouteditpolicy.java

GEF初学者可以用来对照的小例子

/*
 * Created on 2005-1-24
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
package com.example.policies;

import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.Request;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.editpolicies.XYLayoutEditPolicy;
import org.eclipse.gef.requests.CreateRequest;

import com.example.commands.CreateNodeCommand;
import com.example.commands.MoveNodeCommand;
import com.example.model.Diagram;
import com.example.model.Node;
import com.example.parts.NodePart;

/**
 * @author zhanghao
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
public class DiagramLayoutEditPolicy extends XYLayoutEditPolicy {

    protected Command createAddCommand(EditPart child, Object constraint) {
        return null;
    }

    protected Command createChangeConstraintCommand(EditPart child, Object constraint) {
        if (!(child instanceof NodePart))
            return null;
        if (!(constraint instanceof Rectangle))
            return null;

        MoveNodeCommand cmd = new MoveNodeCommand();
        cmd.setNode((Node) child.getModel());
        cmd.setLocation(((Rectangle) constraint).getLocation());
        return cmd;

    }

    protected Command getCreateCommand(CreateRequest request) {
        if (request.getNewObject() instanceof Node) {
            CreateNodeCommand cmd = new CreateNodeCommand();
            cmd.setDiagram((Diagram) getHost().getModel());
            cmd.setNode((Node) request.getNewObject());
            Rectangle constraint = (Rectangle) getConstraintFor(request);
            cmd.setLocation(constraint.getLocation());
            return cmd;
        }
        return null;
    }

    protected Command getDeleteDependantCommand(Request request) {
        return null;
    }
}