Source code for Drawing.java

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package simplermouseinteraction;

import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.geom.GeneralPath;
import java.util.LinkedList;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 * Simple drawing program.
 * 
 * @author pat
 */
public class Drawing extends JPanel implements MouseListener, MouseMotionListener {
    
    GeneralPath p=new GeneralPath();

    LinkedList<GeneralPath> old_paths= new LinkedList<GeneralPath>();
    
    
    public Drawing() {
        setBackground(Color.WHITE); // Make the background color white

        // Necessary for mouse interaction:
        addMouseListener(this);
        addMouseMotionListener(this);
    }

    ///// DRAWING
    /**
     * Draw the disks.
     */
    @Override
    public void paintComponent(Graphics gfx) {
        // This stuff is standard, and should be in any paintComponent method. 
        super.paintComponent(gfx);
        Graphics2D g = (Graphics2D) gfx;
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);

        g.setColor(Color.BLACK);
        g.drawString("Draw something by dragging the mouse!", 10, 20);
        
        g.setColor(Color.RED);
        g.setStroke(new BasicStroke(2));        
        for (GeneralPath old_path : old_paths ) {
            g.draw(old_path);
        }
        
        g.setColor(Color.GREEN);
        g.setStroke(new BasicStroke(2));
        g.draw(p);        
    }

    ///// MOUSE INTERACTION
    // Implementation of MouseListener
    @Override
    public void mouseClicked(MouseEvent me) {
    }

    @Override
    public void mouseEntered(MouseEvent me) {
    }

    @Override
    public void mouseExited(MouseEvent me) {
    }
    
    @Override
    public void mousePressed(MouseEvent me) {
        old_paths.add(p);
        p=new GeneralPath();
        p.moveTo(me.getX(), me.getY());
        repaint();
    }

    @Override
    public void mouseReleased(MouseEvent me) {
    }

    // Implementation of MouseMotionListener
    @Override
    public void mouseDragged(MouseEvent me) {
        p.lineTo(me.getX(), me.getY());
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent me) {        
    }

    public static void main(String[] args) {
        // Construct a new window:
        JFrame frame = new JFrame("Simple Interaction Demo");
        // Dimensions of the window in pixels:
        frame.setSize(640, 480);
        // Quit the program when the window is closed:
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // The window will contain only our panel:
        frame.add(new Drawing());
        // Make the window visible:
        frame.setVisible(true);
    }
}

Last modified on August 17, 2018.