PolyPointLocator.java

/* 
 * Copyright (c) 2006 Stiftung Deutsches Elektronen-Synchroton, 
 * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY.
 *
 * THIS SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "../AS IS" BASIS. 
 * WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE AND 
 * NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR 
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. SHOULD THE SOFTWARE PROVE DEFECTIVE 
 * IN ANY RESPECT, THE USER ASSUMES THE COST OF ANY NECESSARY SERVICING, REPAIR OR 
 * CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. 
 * NO USE OF ANY SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS DISCLAIMER.
 * DESY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, 
 * OR MODIFICATIONS.
 * THE FULL LICENSE SPECIFYING FOR THE SOFTWARE THE REDISTRIBUTION, MODIFICATION, 
 * USAGE AND OTHER RIGHTS AND OBLIGATIONS IS INCLUDED WITH THE DISTRIBUTION OF THIS 
 * PROJECT IN THE FILE LICENSE.HTML. IF THE LICENSE IS NOT INCLUDED YOU MAY FIND A COPY 
 * AT HTTP://WWW.DESY.DE/LEGAL/LICENSE.HTM
 */
package org.csstudio.sds.components.ui.internal.feedback;

import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.Locator;
import org.eclipse.draw2d.Polyline;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.PrecisionRectangle;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gef.handles.HandleBounds;

/**
 * 
 * Places a handle for a polygon or polyline point. The placement is determined by
 * indicating the polyline figure to which the placement is relative, and a value
 * indicating a point index.
 * 
 * @author Sven Wende
 */
public final class PolyPointLocator implements Locator {
	/**
	 * The reference figure.
	 */
	private Polyline _referenceFigure;

	/**
	 * Index of the point, the handle should be placed for.
	 */
	private int _pointIndex;

	/**
	 * Constructs a poly point handle locator.
	 * @param referenceFigure the reference figure ({@link Polyline} or subclasses of it)
	 * @param pointIndex the index of the polygon point for which a handle should be placed
	 */
	public PolyPointLocator(final Polyline referenceFigure, final int pointIndex) {
		assert referenceFigure != null;
		assert pointIndex>=0 : "pointIndex>=0"; //$NON-NLS-1$
		assert referenceFigure.getPoints().size()>pointIndex : "referenceFigure.getPoints().size()>pointIndex"; //$NON-NLS-1$
		_pointIndex = pointIndex;
		_referenceFigure = referenceFigure;
	}

	/**
	 * Returns the Reference Box in the Reference Figure's coordinate system.
	 * The returned Rectangle may be by reference, and should <b>not</b> be
	 * modified.
	 * 
	 * @return the reference box
	 * @since 2.0
	 */
	protected Rectangle getReferenceBox() {
		if (_referenceFigure instanceof HandleBounds) {
			return ((HandleBounds)_referenceFigure).getHandleBounds();
		}
		return _referenceFigure.getBounds();
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void relocate(final IFigure target) {
		Point p = _referenceFigure.getPoints().getPoint(_pointIndex);

		_referenceFigure.translateToAbsolute(p);
		target.translateToRelative(p);
		Rectangle relativeBounds = new PrecisionRectangle(getReferenceBox()
				.getResized(-1, -1));
		Dimension targetSize = target.getPreferredSize();

		relativeBounds.x = p.x - ((targetSize.width + 1) / 2);
		relativeBounds.y = p.y - ((targetSize.height + 1) / 2);

		relativeBounds.setSize(targetSize);
		target.setBounds(relativeBounds);

	}

}