g.java

简易绘图程序

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

class MyPanel extends Panel implements ActionListener,ItemListener,MouseMotionListener,MouseListener
{
 int x1,y1;
 int x2,y2;
 int x,y;
 Vector lines = new Vector();
 Vector colors = new Vector();
 Vector width=new Vector( );
 Button button;
 JButton eraser;
 Choice choice1;
 Choice choice2;
 JToolBar bar;
 Color  newColor=new Color(0,0,0);
 int	linewidth;
 int	mode;
 boolean 	flag; 
 Label  label;
 

 MyPanel()
 {setLayout(null);
  button=new Button("选择颜色");
  button.setBackground(Color.red);
  button.setBounds(20,20,60,30);
  add(button);
  button.addActionListener(this);

  choice1=new Choice( );
  String index[]={"1","2","3","4","5","6","7","8","9","10"};
  for(int j=0;j<=9;j++)
      choice1.add(index[j]);
  choice1.setBounds(100,20,60,30);
  choice1.addItemListener(this);
  add(choice1);
  
  choice2=new Choice( );
  choice2.add("曲线");
  choice2.add("直线");
  choice2.setBounds(180,20,60,30);
  choice2.addItemListener(this);
  add(choice2);

  addMouseMotionListener(this);
  addMouseListener(this);

  flag=false;
  
  Icon 橡皮擦=new ImageIcon("b10.gif");
  eraser=new JButton(橡皮擦);
  eraser.addActionListener(this);
  bar=new JToolBar( );
  bar.add(eraser);
  bar.setBounds(650,20,120,90);
  bar.setRollover(true);
  add(bar);
  eraser.setToolTipText("橡皮擦");
  
  label=new Label("你点我啊！--->");
  label.setBounds(562,20,100,30);
  add(label);
  }

public void paint(Graphics g)
 {if(!flag)
   { Graphics2D g_2=(Graphics2D)g;
     int np = lines.size();
     for   (int i=0; i < np; i++) 
           {String s=(String)width.elementAt(i);
            int k=Integer.parseInt(s);
            BasicStroke bs=new BasicStroke(k,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);
            g_2.setStroke(bs);
            g.setColor((Color)colors.elementAt(i));
            Line2D line=(Line2D)lines.elementAt(i);
            g_2.draw(line);
            }//end of for
     /*if (mode==1) 
        {
	 if (x2 != -1)
            {
             BasicStroke bs=new BasicStroke(linewidth,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);
             g_2.setStroke(bs);
	     g.setColor(newColor);
             Line2D linee=new Line2D.Double(x1,y1,x2,y2);
             g_2.draw(linee);
	    }
	}*/

    }

 else
     {
      g.clearRect(x,y,10,10);
      repaint( );
      int np = lines.size();
      for (int i=0; i < np; i++)
          {Line2D line=(Line2D)lines.elementAt(i);
           if(line.intersects((double)x,(double)y, 10.0,10.0))
             {colors.remove(i);
              width.remove(i);
              lines.remove(i);
              } 
           }
                
      }
 }

public void update(Graphics g)
 { 
  paint(g);
 }

 public void mouseDragged(MouseEvent e) {
        e.consume();
        x=e.getX( );
        y=e.getY( );
        switch (mode) {
            case 1:
                x2 = e.getX();
                y2 = e.getY();
                break;
            case 0:
            default:
                if(!flag)
                {
                 colors.addElement(newColor);
                 String s=new String(""+linewidth);
                 width.addElement(s);
                 lines.addElement(new Line2D.Double(x1,y1,e.getX(),e.getY( )));
                 x1 = e.getX();
                 y1 = e.getY();
                 repaint( );
                 break;
                }
           }
        repaint();
    }


 public void mouseMoved(MouseEvent e){ }

 public void mousePressed(MouseEvent e) {
        e.consume();
        switch (mode) {
            case 1:
                   x1 = e.getX();
                   y1 = e.getY();
                   break;
          case 0:
          default:
             if(!flag)
               {
                x1 = e.getX();
                y1 = e.getY();
                break;
               }
        }
    }

 public void mouseReleased(MouseEvent e) {
        e.consume();
        switch (mode) {
           case 1:
             if(!flag)
               {
                colors.addElement(newColor);
                String s=new String(""+linewidth);
                width.addElement(s);
                lines.addElement(new Line2D.Double(x1,y1,e.getX(),e.getY( )));
                x2 = -1;
                break;
                }
           case 0:
            default:
                break;
        }
        repaint();
    }

 public void mouseEntered(MouseEvent e){}

 public void mouseExited(MouseEvent e){}

 public void mouseClicked(MouseEvent e){}

 public void actionPerformed(ActionEvent e)
 {if(e.getSource( )==button)
     newColor=JColorChooser.showDialog(this,"调色板",Color.black);
  if(e.getSource( )==eraser)
    {
     flag=!flag;
     if(flag==true)
        label.setText("再点击可继续绘图！");
     if(flag==false)
        label.setText("你点我啊！");
    }
 }
 public void itemStateChanged(ItemEvent e)
 {if(e.getSource( )==choice1)
    linewidth=choice1.getSelectedIndex( )+1;
  if(e.getSource( )==choice2)
     mode=choice2.getSelectedIndex( );
  }

}
class MyFrame extends Frame
{
 MyPanel panel;
 MyFrame(String s)
 {super(s);
  panel=new MyPanel( );
  add(panel);
  setBounds(0,0,800,500);
  setVisible(true);
  addWindowListener(new WindowAdapter( )
                    {public void windowClosing(WindowEvent e)
                       {
                        System.exit(0);
                        }
                     }
                    );
 }
}

public class g
{public static void main(String args[])
 {new MyFrame("简易绘图板");
 }
}