elbowhandle.java

开源（Open Source）项目JHotDraw的文档和源程序

/*
 * @(#)ElbowHandle.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 Handle to move an ElbowConnection left/right or up/down.
 */
public class ElbowHandle extends AbstractHandle {

    private int fSegment;
    private int fLastX, fLastY;      // previous mouse position

    public ElbowHandle(LineConnection owner, int segment) {
        super(owner);
        fSegment = segment;
    }

    public void invokeStart(int  x, int  y, DrawingView view) {
        fLastX = x;
        fLastY = y;
    }

    public void invokeStep (int x, int y, int anchorX, int anchorY, DrawingView view) {
        LineConnection line = ownerConnection();
        Point p1 = line.pointAt(fSegment);
        Point p2 = line.pointAt(fSegment+1);
        int ddx = x - fLastX;
        int ddy = y - fLastY;

        Point np1;
        Point np2;
        if (isVertical(p1, p2)) {
            int cx = constrainX(p1.x + ddx);
            np1 = new Point(cx, p1.y);
            np2 = new Point(cx, p2.y);
        } else {
            int cy = constrainY(p1.y + ddy);
            np1 = new Point(p1.x, cy);
            np2 = new Point(p2.x, cy);
        }
        line.setPointAt(np1, fSegment);
        line.setPointAt(np2, fSegment+1);
        fLastX = x;
        fLastY = y;
    }

    private boolean isVertical(Point p1, Point p2) {
        return p1.x == p2.x;
    }

    public Point locate() {
        LineConnection line = ownerConnection();
        int segment = Math.min(fSegment, line.pointCount()-2);
        Point p1 = line.pointAt(segment);
        Point p2 = line.pointAt(segment+1);
        return new Point((p1.x + p2.x)/2, (p1.y + p2.y)/2);
    }

    public void draw(Graphics g) {
        Rectangle r = displayBox();

        g.setColor(Color.yellow);
        g.fillOval(r.x, r.y, r.width, r.height);

        g.setColor(Color.black);
        g.drawOval(r.x, r.y, r.width, r.height);
    }

    private int constrainX(int x) {
        LineConnection line = ownerConnection();
        Figure startFigure = line.start().owner();
        Figure endFigure = line.end().owner();
        Rectangle start = startFigure.displayBox();
        Rectangle end = endFigure.displayBox();
        Insets i1 = startFigure.connectionInsets();
        Insets i2 = endFigure.connectionInsets();

        int r1x, r1width, r2x, r2width;
        r1x = start.x + i1.left;
        r1width = start.width - i1.left - i1.right-1;

        r2x = end.x + i2.left;
        r2width = end.width - i2.left - i2.right-1;

        if (fSegment == 0)
            x = Geom.range(r1x, r1x + r1width, x);
        if (fSegment == line.pointCount()-2)
            x = Geom.range(r2x, r2x + r2width, x);
        return x;
    }

    private int constrainY(int y) {
        LineConnection line = ownerConnection();
        Figure startFigure = line.start().owner();
        Figure endFigure = line.end().owner();
        Rectangle start = startFigure.displayBox();
        Rectangle end = endFigure.displayBox();
        Insets i1 = startFigure.connectionInsets();
        Insets i2 = endFigure.connectionInsets();

        int r1y, r1height, r2y, r2height;
        r1y = start.y + i1.top;
        r1height = start.height - i1.top - i1.bottom-1;
        r2y = end.y + i2.top;
        r2height = end.height - i2.top - i2.bottom-1;

        if (fSegment == 0)
            y = Geom.range(r1y, r1y + r1height, y);
        if (fSegment == line.pointCount()-2)
            y = Geom.range(r2y, r2y + r2height, y);
        return y;
    }

    private LineConnection ownerConnection() {
        return (LineConnection)owner();
    }

}