Mouse drag and drop to draw

[Java Tip]

Code:

import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Container;
import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.TitledBorder;

public class Ellipse extends JFrame {
  DrawingCanvas canvas;

  JLabel location;

  public Ellipse() {
    super();
    Container container = getContentPane();

    canvas = new DrawingCanvas();
    container.add(canvas);

    JPanel panel = new JPanel();
    panel.setLayout(new GridLayout(1, 2));
    panel.add(new JLabel("x,y: ", JLabel.RIGHT));
    location = new JLabel("");
    panel.add(location);

    container.add(panel, BorderLayout.SOUTH);

    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    setSize(600,300);
    setVisible(true);
  }

    public static void main(String arg[]) {
    new Ellipse();
  }

  class DrawingCanvas extends JPanel {
    double x, y, w, h;

    int x1, y1, x2, y2;

    Ellipse2D ellipse;

    Ellipse2D selectedShape;

    Rectangle2D boundingRec;

    Cursor curCursor;
    public DrawingCanvas() {
      x = 20;
      y = 20;
      w = 100;
      h = 75;
      setBackground(Color.white);
      addMouseListener(new MyMouseListener());
      addMouseMotionListener(new MyMouseMotionListener());
    }
    public void paint(Graphics g) {
      Graphics2D g2D = (Graphics2D) g;
      ellipse = new Ellipse2D.Double(x, y, w, h);
      g2D.draw(ellipse);
      if (boundingRec != null) {
        drawHighlightSquares(g2D, boundingRec);
      }
      if (curCursor != null)
        setCursor(curCursor);
    }
    public void drawHighlightSquares(Graphics2D g2D, Rectangle2D r) {
      double x = r.getX();
      double y = r.getY();
      double w = r.getWidth();
      double h = r.getHeight();
      g2D.setColor(Color.black);

      g2D.fill(new Rectangle.Double(x - 3.0, y - 3.0, 6.0, 6.0));
      g2D
          .fill(new Rectangle.Double(x + w * 0.5 - 3.0, y - 3.0, 6.0,
              6.0));
      g2D.fill(new Rectangle.Double(x + w - 3.0, y - 3.0, 6.0, 6.0));
      g2D
          .fill(new Rectangle.Double(x - 3.0, y + h * 0.5 - 3.0, 6.0,
              6.0));
      g2D.fill(new Rectangle.Double(x + w - 3.0, y + h * 0.5 - 3.0, 6.0,
          6.0));
      g2D.fill(new Rectangle.Double(x - 3.0, y + h - 3.0, 6.0, 6.0));
      g2D.fill(new Rectangle.Double(x + w * 0.5 - 3.0, y + h - 3.0, 6.0,
          6.0));
      g2D.fill(new Rectangle.Double(x + w - 3.0, y + h - 3.0, 6.0, 6.0));
    }

    class MyMouseListener extends MouseAdapter {
      public void mousePressed(MouseEvent e) {
        if (ellipse.contains(e.getX(), e.getY())) {
          selectedShape = ellipse;
          if (boundingRec != null)
            boundingRec = ellipse.getBounds2D();
          displayParameters(selectedShape);
        } else { 
          boundingRec = null;
          location.setText("");
        }
        canvas.repaint();
        x1 = e.getX();
        y1 = e.getY();
      }
      public void mouseReleased(MouseEvent e) {
        if (ellipse.contains(e.getX(), e.getY())) {
          boundingRec = ellipse.getBounds2D();
          selectedShape = ellipse;

          displayParameters(selectedShape);
        }

        canvas.repaint();
      }

      public void mouseClicked(MouseEvent e) {
        if (ellipse.contains(e.getX(), e.getY())) {
          selectedShape = ellipse;
          boundingRec = ellipse.getBounds2D();

          displayParameters(selectedShape);
        } else {
          if (boundingRec != null)
            boundingRec = null;
          location.setText("");
        }
        canvas.repaint();
      }
    }
    class MyMouseMotionListener extends MouseMotionAdapter {
      public void mouseDragged(MouseEvent e) {
        if (ellipse.contains(e.getX(), e.getY())) {
          boundingRec = null;
          selectedShape = ellipse;
          x2 = e.getX();
          y2 = e.getY();
          x = x + x2 - x1;
          y = y + y2 - y1;
          x1 = x2;
          y1 = y2;
        }
        if (selectedShape != null)
          displayParameters(selectedShape);
        canvas.repaint();
      }

      public void mouseMoved(MouseEvent e) {
        if (ellipse != null) { 
          if (ellipse.contains(e.getX(), e.getY())) {
            curCursor = Cursor
                .getPredefinedCursor(Cursor.HAND_CURSOR);
          } else {
            curCursor = Cursor.getDefaultCursor();
          }
        }
        canvas.repaint();
      }
    }

    public void displayParameters(Shape shape) {
      double x = selectedShape.getX();
      double y = selectedShape.getY();
      double w = selectedShape.getWidth();
      double h = selectedShape.getHeight();
      String locString = "(" + Double.toString(x) + ","
          + Double.toString(y) + ")";
      String sizeString = "(" + Double.toString(w) + ","
          + Double.toString(h) + ")";
      location.setText(locString);
    }
  }
}