TreeViewerTransferDropListener.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.gef.ui.parts;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DropTargetEvent;

import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPartViewer;
import org.eclipse.gef.Request;
import org.eclipse.gef.RequestConstants;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.commands.CompoundCommand;
import org.eclipse.gef.commands.UnexecutableCommand;
import org.eclipse.gef.dnd.AbstractTransferDropTargetListener;
import org.eclipse.gef.requests.ChangeBoundsRequest;

class TreeViewerTransferDropListener
	extends AbstractTransferDropTargetListener
{

public TreeViewerTransferDropListener(EditPartViewer viewer) {
	super(viewer, TreeViewerTransfer.getInstance());
	setEnablementDeterminedByCommand(true);
}

protected Request createTargetRequest() {
	ChangeBoundsRequest request = new ChangeBoundsRequest(RequestConstants.REQ_MOVE);
	request.setEditParts((List)TreeViewerTransfer.getInstance().getObject());
	return request;
}

protected Command getCommand() {
	CompoundCommand command = new CompoundCommand();

	Iterator iter = ((List)TreeViewerTransfer.getInstance().getObject()).iterator();

	Request  request = getTargetRequest();
	request.setType(isMove() ? RequestConstants.REQ_MOVE : RequestConstants.REQ_ORPHAN);

	while (iter.hasNext()) {
		EditPart editPart = (EditPart)iter.next();
		command.add(editPart.getCommand(request));
	}

	//If reparenting, add all editparts to target editpart.
	if (!isMove()) {
		request.setType(RequestConstants.REQ_ADD);
		if (getTargetEditPart() == null)
			command.add(UnexecutableCommand.INSTANCE);
		else
			command.add(getTargetEditPart().getCommand(getTargetRequest()));
	}
	return command;
}

protected String getCommandName() {
	if (isMove())
		return RequestConstants.REQ_MOVE;
	return RequestConstants.REQ_ADD;
}

protected Collection getExclusionSet() {
	List selection = getViewer().getSelectedEditParts();
	List exclude = new ArrayList(selection);
	exclude.addAll(includeChildren(selection));
	return exclude;
}

protected void handleDragOver() {
	if (TreeViewerTransfer.getInstance().getViewer() != getViewer()) {
		getCurrentEvent().detail = DND.DROP_NONE;
		return;
	}
	getCurrentEvent().feedback = DND.FEEDBACK_SCROLL | DND.FEEDBACK_EXPAND;
	super.handleDragOver();
}

protected EditPart getSourceEditPart() {
	List selection = (List)TreeViewerTransfer.getInstance().getObject();
	if (selection == null
	  || selection.isEmpty()
	  || !(selection.get(0) instanceof EditPart))
		return null;
	return (EditPart)selection.get(0);
}

protected List includeChildren(List list) {
	List result = new ArrayList();
	for (int i = 0; i < list.size(); i++) {
		List children = ((EditPart)list.get(i)).getChildren();
		result.addAll(children);
		result.addAll(includeChildren(children));
	}
	return result;
}

public boolean isEnabled(DropTargetEvent event) {
	if (event.detail != DND.DROP_MOVE)
		return false;
	return super.isEnabled(event);
}

protected boolean isMove() {
	EditPart source = getSourceEditPart();
	List selection = (List)TreeViewerTransfer.getInstance().getObject();
	for (int i = 0; i < selection.size(); i++) {
		EditPart ep = (EditPart)selection.get(i);
		if (ep.getParent() != source.getParent())
			return false;
	}
	return source.getParent() == getTargetEditPart();
}

protected void updateTargetRequest() {
	ChangeBoundsRequest request = (ChangeBoundsRequest)getTargetRequest();
	request.setLocation(getDropLocation());
	request.setType(getCommandName());
}

}