I want help in the drawing of an arc which I want to draw by dragging a portion of a line sement. I Drew the line with this Line2D.Float. I selected two nodes with mouse click. Now I want to drag the line segment, with mouse, bounded by these two nodes to an arc.
I would be grateful for help.
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
public class ArcLines extends JPanel {
Point2D.Double[] points = new Point2D.Double[0];
GeneralPath path = new GeneralPath();
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(path);
g2.setPaint(Color.red);
for(int j = 0; j < points.length; j++)
g2.fill(new Ellipse2D.Double(points[j].x-2, points[j].y-2, 4, 4));
}
public void setPoint(Point2D.Double p, double x, double y) {
p.setLocation(x, y);
setPath();
repaint();
}
public void setNewPoint(Point p) {
addPoint(new Point2D.Double(p.x, p.y));
setPath();
repaint();
}
private void addPoint(Point2D.Double p) {
Point2D.Double[] temp = new Point2D.Double[points.length+1];
System.arraycopy(points, 0, temp, 0, points.length);
temp[points.length] = p;
points = temp;
}
private void setPath() {
path.reset();
path.moveTo((float)points[0].x, (float)points[0].y);
if(points.length == 2) {
path.lineTo((float)points[1].x, (float)points[1].y);
} else if(points.length == 3) {
Point2D.Double ctrl = getOnLineControlPoint();
float ctrlx = (float)ctrl.x;
float ctrly = (float)ctrl.y;
float x2 = (float)points[1].x;
float y2 = (float)points[1].y;
path.quadTo(ctrlx, ctrly, x2, y2);
}
}
private Point2D.Double getOnLineControlPoint() {
Point2D.Double p = new Point2D.Double();
p.x = 2 * points[2].x - (points[0].x + points[1].x)/2;
p.y = 2 * points[2].y - (points[0].y + points[1].y)/2;
return p;
}
public static void main(String[] args) {
ArcLines arcLines = new ArcLines();
PointMaster pm = new PointMaster(arcLines);
arcLines.addMouseListener(pm);
arcLines.addMouseMotionListener(pm);
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(arcLines);
f.setSize(400,400);
f.setLocation(200,200);
f.setVisible(true);
}
}
class PointMaster extends MouseInputAdapter {
ArcLines arcLines;
Point2D.Double selectedPoint;
Point2D.Double offset = new Point2D.Double();
boolean dragging = false;
double PROX_LOC = 3.0;
public PointMaster(ArcLines al) {
arcLines = al;
}
public void mousePressed(MouseEvent e) {
Point p = e.getPoint();
Point2D.Double[] points = arcLines.points;
// Set the end points.
if(points.length < 2) {
arcLines.setNewPoint(p);
return;
}
// With end points set, are we selecting an existing point?
for(int j = 0; j < points.length; j++) {
if(points[j].distance(p) <= PROX_LOC) {
selectedPoint = points[j];
offset.x = p.x - points[j].x;
offset.y = p.y - points[j].y;
dragging = true;
break;
}
}
// Or, are we adding the control point to the line?
if(!dragging && points.length < 3 && isOnPath(p))
arcLines.setNewPoint(p);
}
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;
arcLines.setPoint(selectedPoint, x, y);
}
}
private boolean isOnPath(Point p) {
if(arcLines.points.length == 2) {
double x1 = arcLines.points[0].x;
double y1 = arcLines.points[0].y;
double x2 = arcLines.points[1].x;
double y2 = arcLines.points[1].y;
if(Line2D.ptLineDist(x1, y1, x2, y2, p.x, p.y) <= PROX_LOC)
return true;
}
return false;
}
}