drawcircle.java

if(e.getActionCommand()=="参数法画圆"){ p=11 } } //actionPerformed //实现接口Window

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class drawcircle extends Frame implements WindowListener,ActionListener,MouseListener
{
	MenuBar mb;
	Menu me;
	static Color col=Color.black,cc=Color.red;
	Choice c1,c2,c3;
	Label prompt1,prompt2,prompt3,lab;
    String input;
	static int x0=0,x1=0,y0=0,y1=0,width,height,p=11,q=0,x_0,x_1,y_0,y_1,x_2,y_2,a;
	int linestyle=0xffff,x00=0,x01=0,y00=0,y01=0;
	int point=1,flag=0,r=0;
    Dialog dialog;
	Dimension D1;
	Toolkit TK;
	boolean isXOR=false;//用于确定写模式，true为异或模式，false为写模式
	static Graphics g;
	Image buffer;
	int first=0;
	TextField txt;
	Button b;
	
   	public void display()

	{	//获取屏幕的宽度和高度
		TK=Toolkit.getDefaultToolkit();
		D1=TK.getScreenSize();
		//设置标题栏和窗口的大小		
		setTitle("等距参数法画圆");
		setSize(D1.width,D1.height);
		width=D1.width;
		height=D1.height;
		//为窗口添加事件监听器
		addWindowListener(this);
		addMouseListener(this);
		
		//菜单
	    mb=new MenuBar();
		setMenuBar(mb);
		//mf=new Menu("文件");
		me=new Menu("画圆");	    
	    me.add(new MenuItem("参数法画圆"));
	    me.addActionListener(this);
	    mb.add(me);
	    setVisible(true);
	    g=this.getGraphics();//画笔初始化
	    buffer=this.createImage(width,height);//创建缓冲区的大小
	    	    	   	    
	}//display
	
	
	//实现接口ActionListener的所有方法，用于处理发生在菜单上的事件            
     public void actionPerformed(ActionEvent e)
	 {
	 	isXOR=false; 	    
        
          if(e.getActionCommand()=="参数法画圆"){
          	p=11;
          	 
          		
          	}
     } //actionPerformed
	 
	 //实现接口WindowListener的所有方法，用于处理发生在窗口上的事件  
	  public void windowClosing(WindowEvent e)
	 {
	 	 System.exit(0);
	 }//windowClosing
	
    public void windowOpened(WindowEvent e){ }
    public void windowDeactivated(WindowEvent e){}
    public void windowClosed(WindowEvent e){}
    public void windowIconified(WindowEvent e){}
    public void windowDeiconified(WindowEvent e){}
    public void windowActivated(WindowEvent e){}
	

	
	//实现接口MouseListener的所有方法（5个），用于处理鼠标事件    
	public void mousePressed(MouseEvent e) 
	{
		x0=e.getX();
		y0=e.getY();
		x_0=x0;//起始点坐标
		y_0=y0;
		 	
	 }//mousePressed   
	 
	  
	 public void mouseReleased(MouseEvent e) 
	 {
	 	int m,n,r=0;
	 	
	 	isXOR=false;
	 	x1=e.getX();
	 	y1=e.getY();
	 	x_1=x1;//终止点坐标
		y_1=y1;
       
		x01=0;
		y01=0;
		x00=0;
		y00=0;
		flag=0;
		 
	 if(p==11)//画圆
	 {
	 	r=(int)(Math.sqrt(Math.abs(x1-x0)*Math.abs(x1-x0)+Math.abs(y1-y0)*Math.abs(y1-y0))+0.5);
	 //(new DrawLine()).DDALine(this.g,this.buffer,col,x0,y0,x1,y1,isXOR);
	 (new DrawLine()).circle(this.g,this.buffer,Color.red,x0,y0,r,isXOR);
	 }
            
     }//mouseReleased

     
    public void mouseClicked(MouseEvent e){ } 
    public void mouseEntered(MouseEvent e) { }
    public void mouseExited(MouseEvent e) { }
            
    
       		
    public void mouseMoved(MouseEvent e){ }
    
   
   //用于显示 
   public void paint(Graphics g)
	{
		
		if(first==0) //初始化缓冲区
    	{
    		buffer=this.createImage(width,height);
    		first=1;
    	}    
    	g.drawImage(buffer,0,0,this);
    	
	
   } 
   
/****main*/
    public static void main(String args[])
    {   
    	drawcircle f= new drawcircle();
    	f.display();
    	
    }
}
class DrawLine  
{  
    public void DDALine( Graphics g,Image buffer,Color c,int linestyle,int xu0,int yu0,int xu1,int yu1,boolean isXOR)                                                  //DDA算法
	{
		
			
		float increx,increy,x,y,length;
        int i;int n=0;
        int mark=0x8000;
                  
        if(Math.abs(xu1-xu0)>Math.abs(yu1-yu0))
           length=Math.abs(xu1-xu0);
        else length=Math.abs(yu1-yu0);
        increx=(xu1-xu0)/length;
        increy=(yu1-yu0)/length;
        x=xu0;
        y=yu0;
      
        /*在屏幕上画*/
        if(isXOR) g.setXORMode(c);
		else 
		{
		    g.setPaintMode();
			g.setColor(c);
			
		}
        for(i=1;i<=length;i++)
        {
        	n++;
        	if(n%16>1)  mark=0x8000>>(n%16-1);
        	if(n%16==1) mark=0x8000;
        	if(n%16==0) mark=0x0001;
        	if((linestyle & mark)!=0)
        	  if(length==Math.abs(xu1-xu0))
        
        	  
        	  
        	   
        	      g.fillOval((int)Math.round(x+0.5),(int)Math.round(y+0.5),1,1);
        	    
        	  else
        	   
        	     g.fillOval((int)Math.round(x+0.5),(int)Math.round(y+0.5),1,1);
        	     
        	  
        	x=x+increx;
        	y=y+increy;
        }
    }
    public void circle(Graphics g,Image buffer,Color c,int x0,int y0,int r,boolean isXOR){
    	int x,y,x_2,y_2;
    	float t=0;
    	g.setPaintMode();
    	g.setColor(c);
    	x=r;y=0;
    	g.fillOval(x0,y0,3,3);
    	g.fillOval(x+x0,y+y0,1,1);
    	while(t>=0&&t<=1){
   	    x_2=x;
   	    y_2=y;
   	    t=t+1.00f/100;
    	x=(int)Math.round(r*(1-t*t)/(1+t*t)+0.5);
    	y=(int)Math.round(r*(2*t)/(1+t*t)+0.5);
    	
    	 (new DrawLine()).DDALine(g,buffer,c,0xffff,x_2+x0,y_2+y0,x+x0,y+y0,isXOR);
    
    	 (new DrawLine()).DDALine(g,buffer,c,0xffff,-x_2+x0,y_2+y0,-x+x0,y+y0,isXOR);
    		
    	 (new DrawLine()).DDALine(g,buffer,c,0xffff,-x_2+x0,-y_2+y0,-x+x0,-y+y0,isXOR);
    	
    	 (new DrawLine()).DDALine(g,buffer,c,0xffff,x_2+x0,-y_2+y0,x+x0,-y+y0,isXOR); 
   	}//while                                                            
    	} 
  //将数字字符串转换为数字
	 public long ToData(String s)
	 {
	 	int k=s.length();
	 	long data=s.charAt(0)-48;//charAt:返回指定位置的字符
	 	for(int i=1;i<=k-1;i++)
	 	   {
	 	   	data=10*data+s.charAt(i)-48;
	 	   }
	 	return data;
	 }       
}