// TCubicCurve.java

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.Vector;

public class TCubicCurve extends JFrame {
    DrawingCanvas canvas;
    JLabel label, coords;

    public TCubicCurve() {
        // 1. Assign a name and get the content pane
        super("TCubicCurve"); 
        Container container = getContentPane();

        // 2. Create a display panel 
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(1,2));

        // 3. Add the display labels
        label = new JLabel("Mouse Location (x, y):  ", JLabel.RIGHT);
        panel.add(label);
        panel.add(label);

        coords = new JLabel("");
        panel.add(coords);

        // 4. Add the panel to the container
        container.add(panel, BorderLayout.SOUTH);

        // 5. Add the drawing canvas
        canvas = new DrawingCanvas();
        container.add(canvas);

        // 6. Add the window closing listener and display the
        // frame with proper size
        addWindowListener(new WindowEventHandler());
        pack();
        show();
    }

    // 7. Definition of window listener class
    class WindowEventHandler extends WindowAdapter {
        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    }

    // 8. The main method...
    public static void main(String arg[]) {
        new TCubicCurve();
    }

    // 9. Definition of Drawing Canvas
    class DrawingCanvas extends Canvas {
        // Coordinates to draw a straight line, quadratic curve,
        // and a cubic curve
        float x1,y1,
              xc1cur,yc1cur, xc1new, yc1new,
              xc2cur,yc2cur, xc2new, yc2new,
              x4cur,y4cur, x4new, y4new;

        // Some useful flags
        int pressNo = 0;
        int dragFlag1 = -1;
        int dragFlag2 = -1;
        boolean clearFlag = false;

        // For creating a dashed stroke
        float dashes[] = {5f, 5f};
        BasicStroke stroke;

        // 10. Constructor
        public DrawingCanvas() {
            setBackground(Color.white);
            addMouseListener(new MyMouseListener());
            addMouseMotionListener(new MyMouseMotionListener());
            setSize(400, 400);
            stroke = new BasicStroke(1f, BasicStroke.CAP_BUTT,
                            BasicStroke.JOIN_BEVEL,
                            10f, dashes, 0f);
        }

        // 11. The overriding update() method
        public void update(Graphics g) {
            paint(g);
        }

        // 12. The overriding paint method
        public void paint(Graphics g) {
            // Set up the graphics context
            Graphics2D g2D = (Graphics2D) g;

            // 13. Interactively draw the straight line
            if (pressNo == 1) {
                g2D.setXORMode(getBackground());
                g2D.setColor(Color.black);
                g2D.setStroke(stroke);

                // Erase the currently existing line
                g2D.draw(new Line2D.Float(x1, y1, x4cur, y4cur));
                // Draw the new line
                g2D.draw(new Line2D.Float(x1, y1, x4new, y4new));

                // Update the currently existing coordinate values
                x4cur = x4new;
                y4cur = y4new;
            }

            // 14. Interactively draw the quadratic curve
            else if (pressNo == 2) {
                g2D.setXORMode(getBackground());
                g2D.setColor(Color.black);
                g2D.setStroke(stroke);

                if (dragFlag1 != -1) {
                // Erase the previously existing quadratic curve
                g2D.draw(
                    new QuadCurve2D.Float(x1,y1, xc1cur,yc1cur, x4new,y4new));
                }
                dragFlag1++;  // Reset the drag-flag

                // Draw the new quadratic curve
                g2D.draw(
                    new QuadCurve2D.Float(x1,y1, xc1new,yc1new, x4new,y4new));

                // Update the coordinate values
                xc1cur = xc1new;
                yc1cur = yc1new;
            }

            // 15. Interactively draw the cubic curve
            else if (pressNo == 3) {
                g2D.setXORMode(getBackground());
                g2D.setColor(Color.black);

                if (dragFlag2 != -1) {
                // Erase the currently existing curve
                g2D.draw(
                    new CubicCurve2D.Float(x1,y1, xc1new,yc1new, xc2cur,yc2cur, x4new,y4new));
                }
                dragFlag2++;   // Reset the drag flag

                // Draw the new curve
                g2D.draw(
                    new CubicCurve2D.Float(x1,y1, xc1new,yc1new, xc2new,yc2new, x4new,y4new));

                // Update the current coordinate values
                xc2cur = xc2new;
                yc2cur = yc2new;
            }

            // 16. Clear the guiding straight and quadratic lines
            if (clearFlag) {
                g2D.setXORMode(getBackground());
                g2D.setColor(Color.black);
                g2D.setStroke(stroke);

                g2D.draw(new Line2D.Float(x1, y1, x4new, y4new));
                g2D.draw(
                    new QuadCurve2D.Float(x1,y1, xc1new,yc1new, x4new,y4new));

                // Reset the flag
                clearFlag = false;
            }
        }   

        // 17. Definition of the mouse listener
        class MyMouseListener extends MouseAdapter {
            // 18. When a mouse button is pressed...
            public void mousePressed(MouseEvent e) {
                if (pressNo == 0) { // Note: This is the first press
                    pressNo++;

                    // Update the starting and current coordinates
                    x1 = x4cur = e.getX();
                    y1 = y4cur = e.getY();
                }
                else if (pressNo == 1) { // Note: This is the second press
                    pressNo++;

                    // Update the current control coordinates-1
                    xc1cur = e.getX();
                    yc1cur = e.getY();
                }
                else if (pressNo == 2) { // Note: This is the third press
                    pressNo++;

                    // Update the current control coordinates-2
                    xc2cur = e.getX();
                    yc2cur = e.getY();
                }
            }

            // 19. When the mouse is released...
            public void mouseReleased(MouseEvent e) {
                if (pressNo == 1) {
                   x4new = e.getX();
                   y4new = e.getY();
                   canvas.repaint();
                }   
                else if (pressNo == 2) {
                   xc1new = e.getX();
                   yc1new = e.getY();
                   canvas.repaint();
                }
                else if (pressNo == 3) {
                   xc2new = e.getX();
                   yc2new = e.getY();
                   canvas.repaint();

                   // Reset the flags after the drawing a curve
                   pressNo = 0;
                   dragFlag1 = -1;
                   dragFlag2 = -1;
                   clearFlag = true;
                }
            }
        }

        // 20. Definition of mouse motion listener
        class MyMouseMotionListener extends MouseMotionAdapter {
            // 21. When the mouse is dragged...
            public void mouseDragged(MouseEvent e) {
                if (pressNo == 1) {
                    // Update for the new values of coordinates of the
                    // ending point of a straight line.
                    x4new = e.getX();
                    y4new = e.getY();

                    // Display the location coordinates of the mouse
                    String string = "(" + Integer.toString(e.getX())
                                  + ", " + Integer.toString(e.getY())
                                  + ")";
                    coords.setText(string);

                    // Call the repaint() on canvas
                    canvas.repaint();
                }       
                else if (pressNo == 2) {
                    // Update for the control point-1 of the quadratic
                    // curve. This curve uses the starting and ending points
                    // as those of the straight line.
                    xc1new = e.getX();
                    yc1new = e.getY();

                    // Display the location coordinates of the mouse
                    String string = "(" + Integer.toString(e.getX())
                                  + ", " + Integer.toString(e.getY())
                                  + ")";
                    coords.setText(string);

                    // Call the repaint() on canvas
                    canvas.repaint();
                }
                else if (pressNo == 3) {
                    // Update for the control point-2 of the cubic curve;
                    // The starting and ending points, and the control
                    // point-2 are the same as that of the quadratic curve.
                    xc2new = e.getX();
                    yc2new = e.getY();

                    // Display the location coordinates of the mouse
                    String string = "(" + Integer.toString(e.getX())
                                  + ", " + Integer.toString(e.getY())
                                  + ")";
                    coords.setText(string);

                    // Call the repaint() on canvas
                    canvas.repaint();
                }
            }

            // 22. When the mouse is moved...
            public void mouseMoved(MouseEvent e) {
                // Display the coordinates of the mouse pointer
                String string = "(" + Integer.toString(e.getX()) 
                              + ", " + Integer.toString(e.getY())
                              + ")";
                coords.setText(string);
            }
        }
    }
}