Area - get coordinates

Question

I have an area and would like to get the coordinates directly from this area. The path within this area is closed.
This should work with the interface "PathIterator" from java.awt.geom; I never worked with this interface and don't come to a solution.
Do you have a snippet of code or a tutorial showing how to do this?
Thanks!

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
import javax.swing.event.*;
public class IntersectionRx extends JPanel {
    Ellipse2D e = new Ellipse2D.Double(140, 140, 100, 75);
    Line2D.Double[] lines = getLines(null, 25);
    Line2D.Double line = new Line2D.Double(100, 60, 200, 60);
    Point2D.Double[] intxnPoints = new Point2D.Double[0];
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.red);
        g2.draw(e);
        g2.setPaint(Color.blue);
        for(int j = 0; j < lines.length; j++)
            g2.draw(lines[j]);
        g2.setPaint(Color.green.darker());
        g2.draw(line);
        g2.setPaint(Color.magenta);
        for(int j = 0; j < intxnPoints.length; j++) {
            Point2D.Double p = intxnPoints[j];
            g2.fill(new Ellipse2D.Double(p.x-1.5, p.y-1.5, 4, 4));
    public void setLine(int dx, int dy) {
        double x1 = line.x1 + dx;
        double y1 = line.y1 + dy;
        double x2 = line.x2 + dx;
        double y2 = line.y2 + dy;
        line.setLine(x1, y1, x2, y2);
        checkForLineIntersection();
        repaint();
    private void checkForLineIntersection() {
        List<Point2D.Double> list = new ArrayList<Point2D.Double>();
        for(int j = 0; j < lines.length; j++) {
            if(line.intersectsLine(lines[j])) {
                list.add(getIntersection(line, lines[j]));
        intxnPoints = list.toArray(new Point2D.Double[list.size()]);
    private Point2D.Double getIntersection(Line2D.Double line1, Line2D.Double line2) {
        double x1 = line1.x1;    double y1 = line1.y1;
        double x2 = line1.x2;    double y2 = line1.y2;
        double x3 = line2.x1;    double y3 = line2.y1;
        double x4 = line2.x2;    double y4 = line2.y2;
        double dividend = (x4 - x3)*(y1 - y3) - (y4 - y3)*(x1 - x3);
        double divisor  = (y4 - y3)*(x2 - x1) - (x4 - x3)*(y2 - y1);
        double ua = dividend / divisor;
        Point2D.Double p = new Point2D.Double();
        p.x = x1 + ua * (x2 - x1);
        p.y = y1 + ua * (y2 - y1);
        //System.out.printf("p = [%5.1f, %5.1f]%n", p.x, p.y);
        return p;
    private Line2D.Double[] getLines(AffineTransform at, double flatness) {
        List<Line2D.Double> list = new ArrayList<Line2D.Double>();
        PathIterator pit = e.getPathIterator(at, flatness);
        double[] coords = new double[6];
        double lastX = 0, lastY = 0;
        int count = 0;
        while(!pit.isDone()) {
            int type = pit.currentSegment(coords);
            switch(type) {
                case PathIterator.SEG_MOVETO:
                    lastX = coords[0];
                    lastY = coords[1];
                    break;
                case PathIterator.SEG_LINETO:
                    list.add(new Line2D.Double(lastX, lastY, coords[0], coords[1]));
                    System.out.printf("lines[%d] = [%5.1f, %5.1f, %5.1f, %5.1f]%n",
                                       count++, lastX, lastY, coords[0], coords[1]);
                    lastX = coords[0];
                    lastY = coords[1];
            pit.next();
        return list.toArray(new Line2D.Double[list.size()]);
    public static void main(String[] args) {
        IntersectionRx test = new IntersectionRx();
        LineTransporter controller = new LineTransporter(test);
        test.addMouseListener(controller);
        test.addMouseMotionListener(controller);
        JFrame f = new JFrame("drag green line");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(test);
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
class LineTransporter extends MouseInputAdapter {
    IntersectionRx component;
    final int S = 6;
    Rectangle feeler = new Rectangle(S,S);
    Point start;
    boolean dragging = false;
    Cursor cursor = Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR);
    public LineTransporter(IntersectionRx ir) {
        component = ir;
    public void mousePressed(MouseEvent e) {
        if(component.getCursor() == cursor) {
            start = e.getPoint();
            dragging = true;
    public void mouseReleased(MouseEvent e) {
        dragging = false;
    public void mouseDragged(MouseEvent e) {
        if(dragging) {
            Point end = e.getPoint();
            int dx = end.x - start.x;
            int dy = end.y - start.y;
            start = end;
            component.setLine(dx, dy);
    public void mouseMoved(MouseEvent e) {
        feeler.setLocation(e.getX()-S/2, e.getY()-S/2);
        boolean hovering = false;
        Line2D.Double line = component.line;
        if(line.intersects(feeler)) {
            hovering = true;
            if(component.getCursor() == Cursor.getDefaultCursor())
                component.setCursor(cursor);
        if(!hovering && component.getCursor() == cursor)
            component.setCursor(Cursor.getDefaultCursor());
}