bundles/org.eclipse.draw2d/src/org/eclipse/draw2d/PolygonDecoration.java

/*******************************************************************************
 * Copyright (c) 2000, 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.draw2d;

import org.eclipse.swt.graphics.Color;

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

/**
 * A rotatable, polygon shaped decoration most commonly used for decorating the
 * ends of {@link org.eclipse.draw2d.Polyline polylines}.
 */
public class PolygonDecoration extends Polygon implements RotatableDecoration {

	/**
	 * Template for a triangle that points to the right when the rotation angle
	 * is 0
	 */
	public static final PointList TRIANGLE_TIP = new PointList();
	/**
	 * Template for a triangle that points to the left when the rotation angle
	 * is 0
	 */
	public static final PointList INVERTED_TRIANGLE_TIP = new PointList();

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

		INVERTED_TRIANGLE_TIP.addPoint(0, 1);
		INVERTED_TRIANGLE_TIP.addPoint(0, -1);
		INVERTED_TRIANGLE_TIP.addPoint(-1, 0);
	}

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

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

	/**
	 * @see org.eclipse.draw2d.IFigure#getBackgroundColor()
	 */
	public Color getLocalBackgroundColor() {
		if (super.getLocalBackgroundColor() == null)
			return getForegroundColor();
		return super.getLocalBackgroundColor();
	}

	/**
	 * Returns the points in the PolygonDecoration as a PointList.
	 * 
	 * @return the points in this PolygonDecoration
	 * @since 2.0
	 */
	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;
	}

	/**
	 * Sets the location of this PolygonDecoration.
	 * 
	 * @param p
	 *            the new location
	 */
	public void setLocation(Point p) {
		points = null;
		bounds = null;
		location.setLocation(p);
		transform.setTranslation(p.x, p.y);
	}

	/**
	 * Sets the PolygonDecorations point template to the passed PointList. This
	 * template is an outline of the PolygonDecoration's region. (The default
	 * value is TRIANGLE_TIP which is a triangle whose tip is pointing to the
	 * right).
	 * 
	 * @param pl
	 *            the PointList outline to use as the PolygonDecoration's region
	 * @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
	 * PolygonDecoration's template.
	 * 
	 * @param x
	 *            X scaling
	 * @param y
	 *            Y scaling
	 * @since 2.0
	 */
	public void setScale(double x, double y) {
		points = null;
		bounds = null;
		transform.setScale(x, y);
	}

	/**
	 * Sets the rotation of this decoration so that the decoration points toward
	 * the given reference point.
	 * 
	 * @param ref
	 *            the reference 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 PolygonDecoration.
	 * 
	 * @param angle
	 *            Angle of rotation
	 * @since 2.0
	 */
	public void setRotation(double angle) {
		points = null;
		bounds = null;
		transform.setRotation(angle);
	}

}