EDIT

/*******************************************************************************

 * Copyright (c) 2003, 2010 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.internal.ui.rulers;

import java.util.Iterator;

import java.util.List;

import org.eclipse.draw2d.Figure;

import org.eclipse.draw2d.IFigure;

import org.eclipse.draw2d.geometry.Point;

import org.eclipse.draw2d.geometry.Rectangle;

import org.eclipse.gef.EditPart;

import org.eclipse.gef.GraphicalEditPart;

import org.eclipse.gef.Request;

import org.eclipse.gef.SharedCursors;

import org.eclipse.gef.commands.Command;

import org.eclipse.gef.commands.UnexecutableCommand;

import org.eclipse.gef.editparts.ZoomManager;

import org.eclipse.gef.editpolicies.GraphicalEditPolicy;

import org.eclipse.gef.requests.ChangeBoundsRequest;

/**

 * @author Pratik Shah

 */

public class DragGuidePolicy extends GraphicalEditPolicy {

	private List attachedEditParts = null;

	private IFigure dummyGuideFigure, dummyLineFigure;

	private boolean dragInProgress = false;

	protected IFigure createDummyLineFigure() {

		return new Figure();

	}

	protected GuideFigure createDummyGuideFigure() {

		return new GuidePlaceHolder(getGuideEditPart().isHorizontal());

	}

	/*

	 * Fix for Bug# 65885 If you undo guide creation while dragging that guide,

	 * it was leaving behind drag feedback. This was because by the time

	 * eraseSourceFeedback() was being called, the guide edit part had been

	 * deactivated (and hence eraseSourceFeedback is never called on this

	 * policy). So we make sure that this policy cleans up when it is

	 * deactivated.

	 */

	public void deactivate() {

		removeFeedback();

		super.deactivate();

	}

	private void eraseAttachedPartsFeedback(Request request) {

		if (attachedEditParts != null) {

			ChangeBoundsRequest req = new ChangeBoundsRequest(request.getType());

			req.setEditParts(attachedEditParts);

			Iterator i = attachedEditParts.iterator();

			while (i.hasNext())

				((EditPart) i.next()).eraseSourceFeedback(req);

			attachedEditParts = null;

		}

	}

	public void eraseSourceFeedback(Request request) {

		getGuideEditPart().updateLocationOfFigures(

				getGuideEditPart().getZoomedPosition());

		getHostFigure().setVisible(true);

		getGuideEditPart().getGuideLineFigure().setVisible(true);

		removeFeedback();

		getGuideEditPart().setCurrentCursor(null);

		dragInProgress = false;

		eraseAttachedPartsFeedback(request);

	}

	private List getAttachedEditParts() {

		if (attachedEditParts == null)

			attachedEditParts = getGuideEditPart().getRulerProvider()

					.getAttachedEditParts(

							getHost().getModel(),

							((RulerEditPart) getHost().getParent())

									.getDiagramViewer());

		return attachedEditParts;

	}

	public Command getCommand(Request request) {

		Command cmd;

		final ChangeBoundsRequest req = (ChangeBoundsRequest) request;

		if (isDeleteRequest(req)) {

			cmd = getGuideEditPart().getRulerProvider().getDeleteGuideCommand(

					getHost().getModel());

		} else {

			int pDelta;

			if (getGuideEditPart().isHorizontal()) {

				pDelta = req.getMoveDelta().y;

			} else {

				pDelta = req.getMoveDelta().x;

			}

			if (isMoveValid(getGuideEditPart().getZoomedPosition() + pDelta)) {

				ZoomManager zoomManager = getGuideEditPart().getZoomManager();

				if (zoomManager != null) {

					pDelta = (int) Math.round(pDelta / zoomManager.getZoom());

				}

				cmd = getGuideEditPart().getRulerProvider()

						.getMoveGuideCommand(getHost().getModel(), pDelta);

			} else {

				cmd = UnexecutableCommand.INSTANCE;

			}

		}

		return cmd;

	}

	protected IFigure getDummyGuideFigure() {

		if (dummyGuideFigure == null) {

			dummyGuideFigure = createDummyGuideFigure();

		}

		return dummyGuideFigure;

	}

	protected IFigure getDummyLineFigure() {

		if (dummyLineFigure == null) {

			dummyLineFigure = createDummyLineFigure();

		}

		return dummyLineFigure;

	}

	protected GuideEditPart getGuideEditPart() {

		return (GuideEditPart) getHost();

	}

	protected boolean isDeleteRequest(ChangeBoundsRequest req) {

		int pos, max, min;

		if (getGuideEditPart().isHorizontal()) {

			pos = req.getLocation().x;

			Rectangle zone = getHostFigure().getBounds().getExpanded(

					GuideEditPart.DELETE_THRESHOLD, 0);

			min = zone.x;

			max = min + zone.width;

		} else {

			pos = req.getLocation().y;

			Rectangle zone = getHostFigure().getBounds().getExpanded(0,

					GuideEditPart.DELETE_THRESHOLD);

			min = zone.y;

			max = min + zone.height;

		}

		return pos < min || pos > max;

	}

	protected boolean isMoveValid(int zoomedPosition) {

		boolean result = true;

		ZoomManager zoomManager = getGuideEditPart().getZoomManager();

		int position = zoomedPosition;

		if (zoomManager != null) {

			position = (int) Math.round(position / zoomManager.getZoom());

		}

		Iterator guides = getGuideEditPart().getRulerProvider().getGuides()

				.iterator();

		while (guides.hasNext()) {

			Object guide = guides.next();

			if (guide != getGuideEditPart().getModel()) {

				int guidePos = getGuideEditPart().getRulerProvider()

						.getGuidePosition(guide);

				if (Math.abs(guidePos - position) < GuideEditPart.MIN_DISTANCE_BW_GUIDES) {

					result = false;

					break;

				}

			}

		}

		return result;

	}

	private void removeFeedback() {

		if (getDummyGuideFigure().getParent() != null) {

			getDummyGuideFigure().getParent().remove(getDummyGuideFigure());

		}

		if (getDummyLineFigure().getParent() != null) {

			getDummyLineFigure().getParent().remove(getDummyLineFigure());

		}

	}

	private void showAttachedPartsFeedback(ChangeBoundsRequest request) {

		ChangeBoundsRequest req = new ChangeBoundsRequest(request.getType());

		req.setEditParts(getAttachedEditParts());

		if (getGuideEditPart().isHorizontal())

			req.setMoveDelta(new Point(0, request.getMoveDelta().y));

		else

			req.setMoveDelta(new Point(request.getMoveDelta().x, 0));

		Iterator i = getAttachedEditParts().iterator();

		while (i.hasNext())

			((EditPart) i.next()).showSourceFeedback(req);

	}

	public void showSourceFeedback(Request request) {

		if (!dragInProgress) {

			dragInProgress = true;

			// add the placeholder guide figure to the ruler

			getHostFigure().getParent().add(getDummyGuideFigure(), 0);

			((GraphicalEditPart) getHost().getParent()).setLayoutConstraint(

					getHost(), getDummyGuideFigure(), new Integer(

							getGuideEditPart().getZoomedPosition()));

			getDummyGuideFigure().setBounds(getHostFigure().getBounds());

			// add the invisible placeholder line figure to the primary viewer

			getGuideEditPart().getGuideLayer().add(getDummyLineFigure(), 0);

			getGuideEditPart().getGuideLayer().setConstraint(

					getDummyLineFigure(),

					new Boolean(getGuideEditPart().isHorizontal()));

			getDummyLineFigure().setBounds(

					getGuideEditPart().getGuideLineFigure().getBounds());

			// move the guide being dragged to the last index so that it's drawn

			// on

			// top of other guides

			List children = getHostFigure().getParent().getChildren();

			children.remove(getHostFigure());

			children.add(getHostFigure());

		}

		ChangeBoundsRequest req = (ChangeBoundsRequest) request;

		if (isDeleteRequest(req)) {

			getHostFigure().setVisible(false);

			getGuideEditPart().getGuideLineFigure().setVisible(false);

			getGuideEditPart().setCurrentCursor(SharedCursors.ARROW);

			eraseAttachedPartsFeedback(request);

		} else {

			int newPosition;

			if (getGuideEditPart().isHorizontal()) {

				newPosition = getGuideEditPart().getZoomedPosition()

						+ req.getMoveDelta().y;

			} else {

				newPosition = getGuideEditPart().getZoomedPosition()

						+ req.getMoveDelta().x;

			}

			getHostFigure().setVisible(true);

			getGuideEditPart().getGuideLineFigure().setVisible(true);

			if (isMoveValid(newPosition)) {

				getGuideEditPart().setCurrentCursor(null);

				getGuideEditPart().updateLocationOfFigures(newPosition);

				showAttachedPartsFeedback(req);

			} else {

				getGuideEditPart().setCurrentCursor(SharedCursors.NO);

				getGuideEditPart().updateLocationOfFigures(

						getGuideEditPart().getZoomedPosition());

				eraseAttachedPartsFeedback(request);

			}

		}

	}

	public boolean understandsRequest(Request req) {

		return req.getType().equals(REQ_MOVE);

	}

}