shortestdistanceconnector.java

开源（Open Source）项目JHotDraw的文档和源程序

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

package CH.ifa.draw.figures;

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

/**
 * A ShortestDistance locates connection points by
 * finding the shortest distance between the start and
 * end of the connection.
 * It doesn't connect to the ares defined by Figure.connectionInsets()
 * @see Figure#connectionInsets
 * @see Connector
 */
public class ShortestDistanceConnector extends AbstractConnector {

    /*
     * Serialization support.
     */
    private static final long serialVersionUID = -2273446020593433887L;

    public ShortestDistanceConnector() { // only used for Storable implementation
        super();
    }

    public ShortestDistanceConnector(Figure owner) {
        super(owner);
    }

    public Point findStart(ConnectionFigure connection) {
        return findPoint(connection, true);
    }

    public Point findEnd(ConnectionFigure connection) {
        return findPoint(connection, false);
    }

    protected Point findPoint(ConnectionFigure connection, boolean getStart) {
        Figure startFigure = connection.start().owner();
        Figure endFigure = connection.end().owner();

        Rectangle r1 = startFigure.displayBox();
        Rectangle r2 = endFigure.displayBox();

        Insets i1 = startFigure.connectionInsets();
        Insets i2 = endFigure.connectionInsets();

        Point p1, p2;
        Point start = null, end = null, s = null, e = null;
        long len2 = Long.MAX_VALUE, l2;
        int x1, x2, y1, y2; // connection points
        int xmin, xmax, ymin, ymax;

        // X-dimension
        // constrain width connection insets
        int r1x, r1width, r2x, r2width, r1y, r1height, r2y, r2height;
        r1x = r1.x + i1.left;
        r1width = r1.width - i1.left - i1.right-1;
        r2x = r2.x + i2.left;
        r2width = r2.width - i2.left - i2.right-1;

        // find x connection point
        if (r1x + r1width < r2x) {
            x1 = r1x + r1width;
            x2 = r2x;
        } else if (r1x > r2x + r2width) {
            x1 = r1x;
            x2 = r2x + r2width;
        } else {
            xmax = Math.max(r1x, r2x);
            xmin = Math.min(r1x+r1width, r2x+r2width);
            x1 = x2 = (xmax + xmin) /2;
        }

        // Y-Dimension
        // constrain with connection insets
        r1y = r1.y + i1.top;
        r1height = r1.height - i1.top - i1.bottom-1;
        r2y = r2.y + i2.top;
        r2height = r2.height - i2.top - i2.bottom-1;

        // y connection point
        if (r1y + r1height < r2y) {
            y1 = r1y + r1height;
            y2 = r2y;
        } else if (r1y > r2y + r2height) {
            y1 = r1y;
            y2 = r2y + r2height;
        } else {
            ymax = Math.max(r1y, r2y);
            ymin = Math.min(r1y+r1height, r2y+r2height);
            y1 = y2 = (ymax + ymin) /2;
        }
        // find shortest connection
        for (int i = 0; i < 4; i++) {
            switch(i) {
            case 0:
                // EAST-WEST
                p1 = Geom.east(r1);
                p2 = Geom.west(r2);
                s = new Point(p1.x, y1);
                e = new Point(p2.x, y2);
                break;
            case 1:
                // WEST-EAST
                p1 = Geom.west(r1);
                p2 = Geom.east(r2);
                s = new Point(p1.x, y1);
                e = new Point(p2.x, y2);
                break;
            case 2:
                // NORTH-SOUTH
                p1 = Geom.north(r1);
                p2 = Geom.south(r2);
                s = new Point(x1, p1.y);
                e = new Point(x2, p2.y);
                break;
            case 3:
                // SOUTH-NORTH
                p1 = Geom.south(r1);
                p2 = Geom.north(r2);
                s = new Point(x1, p1.y);
                e = new Point(x2, p2.y);
                break;
            }
            l2 = Geom.length2(s.x, s.y, e.x, e.y);
            if (l2 < len2) {
                start = s;
                end = e;
                len2 = l2;
            }
        }
        if (getStart)
            return start;
        return end;
    }

}