PolylineDecoration.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.draw2d;

import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.PointList;
import org.eclipse.draw2d.geometry.Transform;

/**
 * A decorative Figure intended to be placed on a {@link Polyline}. It has the default 
 * shape of right-pointing triangle.
 */
public class PolylineDecoration
	extends Polyline
	implements RotatableDecoration
{

/** A triangle template */
public static final PointList TRIANGLE_TIP = new PointList();

static {
	TRIANGLE_TIP.addPoint(-1, 1);
	TRIANGLE_TIP.addPoint(0, 0);
	TRIANGLE_TIP.addPoint(-1, -1);
}

private Point location = new Point();
private PointList template = TRIANGLE_TIP;
private Transform transform = new Transform();

/**
 * Constructs a PolylineDecoration. Defaults the PolylineDecoration to fill its region 
 * with black.
 * 
 * @since 2.0 
 */
public PolylineDecoration() {
	setBackgroundColor(ColorConstants.black);
	setScale(7, 3);
}

/**
 * @see Polyline#getPoints()
 */
public PointList getPoints() {
	if (points == null) {
		points = new PointList();
		for (int i = 0; i < template.size(); i++)
			points.addPoint(transform.getTransformed(template.getPoint(i)));
	}
	return points;
}

/**
 * @see IFigure#setLocation(Point)
 */
public void setLocation(Point p) {
	points = null;
	bounds = null;
	location.setLocation(p);
	transform.setTranslation(p.x, p.y);
}

/**
 * Sets the PolylineDecoration's point template. This template is an outline of the 
 * PolylineDecoration's region. (The default value is TRIANGLE_TIP which is a triangle 
 * whose tip is pointing to the right).
 * 
 * @param pl the template
 * @since 2.0
 */
public void setTemplate(PointList pl) {
	erase();
	template = pl;
	points = null;
	bounds = null;
	repaint();
}

/**
 * Sets the amount of scaling to be done along X and Y axes on the PolylineDecoration's 
 * template.
 *
 * @param x the x scale
 * @param y the y scale
 * @since 2.0
 */
public void setScale(double x, double y) {
	points = null;
	bounds = null;
	transform.setScale(x, y);
}

/**
 * @see RotatableDecoration#setReferencePoint(Point)
 */
public void setReferencePoint(Point ref) {
	Point pt = Point.SINGLETON;
	pt.setLocation(ref);
	pt.negate().translate(location);
	setRotation(Math.atan2(pt.y, pt.x));
}

/**
 * Sets the angle by which rotation is to be done on the PolylineDecoration.
 * 
 * @param angle the angle of rotation
 * @since 2.0
 */
public void setRotation(double angle) {
	points = null;
	bounds = null;
	transform.setRotation(angle);
}

}