polylineconnector.java

开源（Open Source）项目JHotDraw的文档和源程序

/*
 * @(#)PolyLineConnector.java 5.2
 *
 */

package CH.ifa.draw.figures;

import java.awt.*;
import java.io.IOException;
import CH.ifa.draw.framework.*;
import CH.ifa.draw.standard.*;
import CH.ifa.draw.util.*;

/**
 * PolyLineConnector finds connection points on a
 * PolyLineFigure.
 *
 * @see PolyLineFigure
 */
public class PolyLineConnector extends ChopBoxConnector {

    /*
     * Serialization support.
     */
    private static final long serialVersionUID = 6018435940519102865L;

    public PolyLineConnector() {
        super();
    }

    /**
     * Constructs a connector with the given owner figure.
     */
    public PolyLineConnector(Figure owner) {
        super(owner);
    }

    protected Point chop(Figure target, Point from) {
        PolyLineFigure p = (PolyLineFigure)owner();
        // *** based on PolygonFigure's heuristic
        Point ctr = p.center();
        int cx = -1;
        int cy = -1;
        long len = Long.MAX_VALUE;

        // Try for points along edge

        for (int i = 0; i < p.pointCount()-1; i++) {
            Point p1 = p.pointAt(i);
            Point p2 = p.pointAt(i+1);
            Point chop = Geom.intersect(p1.x,
                                 p1.y,
                                 p2.x,
                                 p2.y,
                                 from.x,
                                 from.y,
                                 ctr.x,
                                 ctr.y);
            if (chop != null) {
                long cl = Geom.length2(chop.x, chop.y, from.x, from.y);
                if (cl < len) {
                    len = cl;
                    cx = chop.x;
                    cy = chop.y;
                }
            }
        }
        // if none found, pick closest vertex
        //if (len ==  Long.MAX_VALUE) {
        { // try anyway
            for (int i = 0; i < p.pointCount(); i++) {
                Point pp = p.pointAt(i);
                long l = Geom.length2(pp.x, pp.y, from.x, from.y);
                if (l < len) {
                    len = l;
                    cx = pp.x;
                    cy = pp.y;
                }
            }
        }
        return new Point(cx, cy);
    }
}