drawtest.java

这是一个java程序

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.Vector;

public class DrawTest extends Applet{
    DrawPanel panel;
    DrawControls controls;

    public void init() {
		setLayout(new BorderLayout());
		panel = new DrawPanel();
		controls = new DrawControls(panel);
		add("Center", panel);
		add("North",controls);
	}

    public static void main(String args[]) {
		Frame f = new Frame("DrawTest");
		DrawTest drawTest = new DrawTest();
		drawTest.init();
		drawTest.start();	
		f.add("Center", drawTest);
		f.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e){
				System.exit(1);	
			}
		});
		f.setSize(400, 250);
		f.show();
    }
    public String getAppletInfo() {
        return "A simple drawing program.";
    }
}

class DrawPanel extends Panel implements MouseListener, MouseMotionListener {
    public static final int LINES = 0;
    public static final int POINTS = 1;
    public static final int RECTANGLES = 2;
    public static final int OVALS = 3;
    
    int mode = LINES;
    int x1,y1;
    int x2,y2;    
    Vector lines = new Vector();
    Vector rectangles = new Vector();
    Vector ovals = new Vector();   
    Vector Lcolors = new Vector();
    Vector Rcolors = new Vector();
    Vector Ocolors = new Vector(); 

    public DrawPanel() {
		setBackground(Color.white);
		addMouseMotionListener(this);
		addMouseListener(this);
    }

    public void setDrawMode(int mode) {
		switch (mode) {
		  case LINES:
		  case POINTS:
		  case RECTANGLES:
		  case OVALS:
		    this.mode = mode;
		    break;
		  default:
		    throw new IllegalArgumentException();
		}
    }

    public void mouseDragged(MouseEvent e) {
        e.consume();
        switch (mode) {
            case LINES:
		  	case RECTANGLES:
		  	case OVALS:            
                x2 = e.getX();
                y2 = e.getY();
                break;
            case POINTS:
            default:
                Lcolors.addElement(getForeground());
                lines.addElement(new Rectangle(x1, y1, e.getX(), e.getY()));
                x1 = e.getX();
                y1 = e.getY();
                break;
        }
        repaint();
    }

    public void mouseMoved(MouseEvent e) { }

    public void mousePressed(MouseEvent e) {
        e.consume();
        switch (mode) {
            case LINES:
            case RECTANGLES:
		  	case OVALS:
                x1 = e.getX();
                y1 = e.getY();
                x2 = -1;
                break;
            case POINTS:
            default:
                Lcolors.addElement(getForeground());
                lines.addElement(new Rectangle(e.getX(), e.getY(), -1, -1));
                x1 = e.getX();
                y1 = e.getY();
                repaint();
                break;
        }
    }

    public void mouseReleased(MouseEvent e) {
        e.consume();
        switch (mode) {
            case LINES:
                Lcolors.addElement(getForeground());
                lines.addElement(new Rectangle(x1, y1, e.getX(), e.getY()));
                x2 = -1;
                break;                
			case RECTANGLES:
                Rcolors.addElement(getForeground());
                rectangles.addElement(new Rectangle(x1, y1, e.getX(), e.getY()));
                x2 = -1;
                break;                			
		  	case OVALS:
                Ocolors.addElement(getForeground());
                ovals.addElement(new Rectangle(x1, y1, e.getX(), e.getY()));
                x2 = -1;
                break;                  
            case POINTS:
            default:
                break;
        }
        repaint();
    }

    public void mouseEntered(MouseEvent e) { }

    public void mouseExited(MouseEvent e) { }

    public void mouseClicked(MouseEvent e) { }

    public void paint(Graphics g) {
		int np = lines.size();	
		for (int i=0; i < np; i++) {
		    Rectangle p = (Rectangle)lines.elementAt(i);
		    g.setColor((Color)Lcolors.elementAt(i));
		    if (p.width != -1) {
				g.drawLine(p.x, p.y, p.width, p.height);
		    } else {
				g.drawLine(p.x, p.y, p.x, p.y);
		    }
		}
		
		np = rectangles.size();
		for (int i=0; i < np; i++) {
		    Rectangle p = (Rectangle)rectangles.elementAt(i);
		    g.setColor((Color)Rcolors.elementAt(i));
		    if (p.width != -1) {
				g.drawRect(p.x, p.y, p.width, p.height);
		    }
		}
		
		np = ovals.size();
		for (int i=0; i < np; i++) {
		    Rectangle p = (Rectangle)ovals.elementAt(i);
		    g.setColor((Color)Ocolors.elementAt(i));
		    if (p.width != -1) {
				g.drawOval(p.x, p.y, p.width, p.height);
		    }
		}				

		g.setColor(getForeground());		
		switch(mode){
			case LINES:
			    if (x2 != -1) {
		    	g.drawLine(x1, y1, x2, y2);
			    }
			    break;
			case RECTANGLES:
			    if (x2 != -1) {
		    	g.drawRect(x1, y1, x2, y2);
			    }			    
			    break;
			case OVALS:
			    if (x2 != -1) {
		    	g.drawOval(x1, y1, x2, y2);
			    }			    
			    break;			
		}
    }
}

class DrawControls extends Panel 
	implements ItemListener,MouseListener{
	DrawPanel target;
	
	public DrawControls(DrawPanel target) {
		this.target = target;
		setLayout(new FlowLayout());
		setBackground(Color.lightGray);
		target.setForeground(Color.red);	
		
		Panel pcolor = new Panel();
		pcolor.setLayout(new GridLayout(1,8));
		Label l;		
		pcolor.add(l = new Label());
		l.setBackground(Color.red);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.green);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.blue);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.yellow);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.pink);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.orange);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.cyan);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.magenta);
		l.addMouseListener(this);
		
		pcolor.add(l = new Label());
		l.setBackground(Color.gray);
		l.addMouseListener(this);				
		
		pcolor.add(l = new Label());
		l.setBackground(Color.black);
		l.addMouseListener(this);						
		
		add(pcolor);			

		Choice shapes = new Choice();
		shapes.addItemListener(this);
		shapes.addItem("Lines");
		shapes.addItem("Points");
		shapes.addItem("Rectangles");
		shapes.addItem("Ovals");
		shapes.setBackground(Color.lightGray);
		add(shapes);
    }

	public void itemStateChanged(ItemEvent e) {
		if (e.getSource() instanceof Choice) {
			String choice = (String) e.getItem();
			if (choice.equals("Lines")) {
				target.setDrawMode(DrawPanel.LINES);
			}else if (choice.equals("Points")) {
				target.setDrawMode(DrawPanel.POINTS);
			}else if (choice.equals("Rectangles")) {
				target.setDrawMode(DrawPanel.RECTANGLES);
			}else if (choice.equals("Ovals")) {
				target.setDrawMode(DrawPanel.OVALS);
			}
		}
	}
	
	public void mouseEntered(MouseEvent e) { }	
	public void mouseExited(MouseEvent e) {	}
	public void mouseMoved(MouseEvent e) { }
	public void mousePressed(MouseEvent e) { }
	public void mouseClicked(MouseEvent e) { 
		if (e.getSource() instanceof Label) {
			target.setForeground(((Component)e.getSource()).getBackground());
		}	
	}
	public void mouseReleased(MouseEvent e) { }		
}