Point in a CubicCurve2D - Not in the boundary of the shape

Question

Hello, I have a problem, because I wanna know, when a point is in the CubicCurve2D line (not inside the boundary of the shape), but I just find on the API when the point is inside the boundary of the shape... Some idea??
Thanks,
Javi.

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
public class WalkTheLine extends JPanel
    CubicCurve2D curve;
    Point2D.Double[] points;
    Point2D.Double hit;
    public WalkTheLine()
        double x1 = 100;
        double y1 = 90;
        double ctrlx1 = 100;
        double ctrly1 = 270;
        double ctrlx2 = 300;
        double ctrly2 = 90;
        double x2 = 300;
        double y2 = 270;
        points = new Point2D.Double[4];
        points[0] = new Point2D.Double(x1, y1);
        points[1] = new Point2D.Double(ctrlx1, ctrly1);
        points[2] = new Point2D.Double(ctrlx2, ctrly2);
        points[3] = new Point2D.Double(x2, y2);
        curve = new CubicCurve2D.Double();
        curve.setCurve(points, 0);
        hit = new Point2D.Double();
    protected void paintComponent(Graphics g)
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.blue);
        g2.draw(curve);
        g2.setPaint(Color.red);
        for(Point2D.Double p : points)
            g2.fill(new Ellipse2D.Double(p.x-2, p.y-2, 4, 4));
        g2.setPaint(Color.green.darker());
        g2.fill(new Ellipse2D.Double(hit.x-2, hit.y-2, 4, 4));
    public void setPoint(int index, double x, double y)
        points[index].setLocation(x, y);
        curve.setCurve(points, 0);
        repaint();
    public void setHit(Point p)
        hit.setLocation(p);
        repaint();
    public static void main(String[] args)
        WalkTheLine walkTheLine = new WalkTheLine();
        PointMover mover = new PointMover(walkTheLine);
        walkTheLine.addMouseListener(mover);
        walkTheLine.addMouseMotionListener(mover);
        JFrame f = new JFrame(walkTheLine.getClass().getName());
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(walkTheLine);
        f.add(mover.getControlPanel(), "South");
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
class PointMover extends MouseInputAdapter
    WalkTheLine walkTheLine;
    int selectedIndex;
    Point2D.Double offset;
    boolean dragging;
    int methodFlag;
    final int MIN_DISTANCE = 5;
    final int ITERATOR   = 0;
    final int PARAMETRIC = 1;
    public PointMover(WalkTheLine wtl)
        walkTheLine = wtl;
        offset = new Point2D.Double();
        dragging = false;
        methodFlag = ITERATOR;
    private boolean isOnCurve(Point p)
        switch(methodFlag)
            case ITERATOR:   return withIterator(p);
            case PARAMETRIC: return withParametric(p);
            default: return false;
    private boolean withIterator(Point p)
        // flatness ~ number of segments for initial curve:
        //     0.001 ~ 463;  0.01 ~ 199;  0.1 ~ 57
        PathIterator pit = walkTheLine.curve.getPathIterator(null, 0.001);
        double[] coords = new double[6];
        Point2D.Double next = new Point2D.Double();
        double minDist = 1.75;
        while(!pit.isDone())
            int type = pit.currentSegment(coords);
            switch(type)
                case PathIterator.SEG_MOVETO:
                case PathIterator.SEG_LINETO:
                    next.x = coords[0];
                    next.y = coords[1];
                    break;
                case PathIterator.SEG_QUADTO:  break;
                case PathIterator.SEG_CUBICTO: break;
                case PathIterator.SEG_CLOSE:   break;
                default:
                    System.out.println("unexpected type: " + type);
            if(next.distance(p) < minDist)
                return true;
            pit.next();
       return false;
     *  from: PathIterator.SEG_CUBETO
     *  P(t) = B(3,0)*CP + B(3,1)*P1 + B(3,2)*P2 + B(3,3)*P3
     *  0 <= t <= 1
     *  B(n,m) = mth coefficient of nth degree Bernstein polynomial
     *         = C(n,m) * t^(m) * (1 - t)^(n-m)
     *  C(n,m) = Combinations of n things, taken m at a time
     *         = n! / (m! * (n-m)!)
    private boolean withParametric(Point p)
        Point2D.Double[] points = walkTheLine.points;
        int w = walkTheLine.getWidth();
        double minDist = 1.75;
        Point2D.Double next = new Point2D.Double();
        for(int j = 0; j <= w; j++)
            double t = (double)j/w;
            next.x = B(3,0,t)*points[0].x + B(3,1,t)*points[1].x +
                     B(3,2,t)*points[2].x + B(3,3,t)*points[3].x;
            next.y = B(3,0,t)*points[0].y + B(3,1,t)*points[1].y +
                     B(3,2,t)*points[2].y + B(3,3,t)*points[3].y;
            if(next.distance(p) < minDist)
                return true;
        return false;
    private double B(int n, int m, double t)
        int c = factorial(n) / (factorial(m) * factorial(n-m));
        return c * Math.pow(t,m) * Math.pow(1.0 - t, n-m);
    private int factorial(int n)
        return n > 1 ? n*factorial(n-1) : n == 0 ? 1 : n;
    public void mouseMoved(MouseEvent e)
        Point p = e.getPoint();
        Point2D.Double hit = walkTheLine.hit;
        if(isOnCurve(p))
            walkTheLine.setHit(p);
    public void mousePressed(MouseEvent e)
        Point p = e.getPoint();
        Point2D.Double[] points = walkTheLine.points;
        for(int j = 0; j < points.length; j++)
            if(points[j].distance(p) < MIN_DISTANCE)
                selectedIndex = j;
                offset.x = p.x - points[j].x;
                offset.y = p.y - points[j].y;
                dragging = true;
                break;
    public void mouseReleased(MouseEvent e)
        dragging = false;
    public void mouseDragged(MouseEvent e)
        if(dragging)
            double x = e.getX() - offset.x;
            double y = e.getY() - offset.y;
            walkTheLine.setPoint(selectedIndex, x, y);
    protected JPanel getControlPanel()
        String[] ids = { "iterator", "parametric" };
        JPanel panel = new JPanel();
        ButtonGroup group = new ButtonGroup();
        ActionListener l = new ActionListener()
            public void actionPerformed(ActionEvent e)
                JRadioButton rb = (JRadioButton)e.getSource();
                String ac = rb.getActionCommand();
                if(ac.equals("iterator"))
                    methodFlag = ITERATOR;
                if(ac.equals("parametric"))
                    methodFlag = PARAMETRIC;
        for(int j = 0; j < ids.length; j++)
            JRadioButton rb = new JRadioButton(ids[j], j==0);
            rb.setActionCommand(ids[j]);
            rb.addActionListener(l);
            group.add(rb);
            panel.add(rb);
        return panel;
}