j_draw.java

一个十分好的java基础学习的课件

// ////////////////////////////////////////////////////////
// 
// J_Draw.java
// 

// ////////////////////////////////////////////////////////

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


public class J_Draw extends JPanel
{
    private Vector m_vectorSet= new Vector( );

    public J_Draw( )
    {
        addMouseListener( new MouseAdapter( )
            {
                public void mousePressed(MouseEvent e)
                {
                    Vector v= new Vector( );
                    Point p= new Point(e.getX( ), e.getY( ));
                    m_vectorSet.add(v);
                    v.add(p);
                } // End of method: mousePressed
            } // End of the anonymous inner class, which implements MouseAdapter
        ); // End of invoking addMouseAdapter

        addMouseMotionListener( new MouseMotionAdapter( )
            {
                public void mouseDragged(MouseEvent e) 
                {
                    Point p= new Point(e.getX( ), e.getY( ));
                    int n= m_vectorSet.size( )-1;
                    Vector v= (Vector)m_vectorSet.get(n);
                    v.add(p);
                    repaint( );
                } // End of method: mouseDragged
            } // End of the anonymous inner class, which implements MouseMotionAdapter
        ); // End of invoking addMouseMotionAdapter

    } // End of constructor: J_Draw

    public void paintComponent(Graphics g)
    {
        super.paintComponent( g );
        Vector v;
        Point s, t;
        int i, j, m;
        int n= m_vectorSet.size( );
        for (i= 0; i< n; i++)
        {
            v= (Vector)m_vectorSet.get(i);
            m= v.size( )-1;
            for (j= 0; j< m; j++)
            {
                s= (Point)v.get(j);
                t= (Point)v.get(j+1);
                g.drawLine(s.x, s.y, t.x, t.y);
            } // End of inner loop: for
        } // End of outer loop: for
    } // End of method: paint

    public Dimension getPreferredSize( )
    {
        return new Dimension( 250, 120 );
    } // End of method: getPreferredSize

} // End of class: J_Draw