刷新屏幕但不清除以前形状的问题

Question

我正在模拟sierpinski三角形的混沌游戏。

我试图画一个新的点，没有清除最后一个。随着GUI上创建sierpinski三角形图像的点数增加，绘制点的速度因for循环而减少。我想在没有for循环的情况下运行该程序，但每次重绘时，前一个点都会清除。

到目前为止，我有这个程序的工作版本，但我希望它更有效率。

这是我的整个程序的代码。

import javax.swing.*; //JFrame and JPanel 
import java.awt.*; //Color and Container 
import javax.swing.JOptionPane; 
import java.awt.event.*; 
import java.util.Scanner; 
import java.io.*; 
import java.util.Random; 
import java.util.ArrayList; 
import java.util.List; 

/** 
* Write a description of class ChaosGame here. 
* 
* @author (your name) 
* @version (a version number or a date) 
*/ 
public class ChaosGame 
{ 
    public static void main(String[] args) { 
     JFrame theGUI = new JFrame("Chaos Game"); 
     theGUI.setSize(800, 800); 
     theGUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     ColorPanel panel = new ColorPanel(Color.white); 
     Container pane = theGUI.getContentPane(); 
     pane.add(panel); 
     theGUI.setVisible(true); 
    } 
} 
class ColorPanel extends JPanel implements MouseMotionListener, MouseListener{ 
    private Random random = new Random(); 
    private Seed s; 
    private Red r; 
    private Blue b; 
    private Green gr; 
    private boolean followMouse = true; 
    javax.swing.Timer timer; 
    javax.swing.Timer arraytimer; 
    private int x, y; 
    private int newx, newy; 
    private int redx = 100; 
    private int redy = 660; 
    private int bluex = 700; 
    private int bluey = 660; 
    private int greenx = 400; 
    private int greeny = 140; 
    private int pointx, pointy; 
    private int seedx, seedy; 
    private int i; 
    private int dotcounter; 
    private Point[] p = new Point[10000]; 

    public ColorPanel(Color backcolor){ 
     setBackground(backcolor); 
     s = new Seed(400, 400, Color.YELLOW); 
     r = new Red(100, 660, Color.RED); 
     b = new Blue(700, 660, Color.BLUE); 
     gr = new Green(400, 140, Color.GREEN); 
     i = 0; 
     dotcounter = 0; 
     addMouseListener(this); 
     addMouseMotionListener(this); 
     this.setFocusable(true); 
     timer = new javax.swing.Timer(1, new MoveListener()); 
     arraytimer = new javax.swing.Timer(1, new ArrayTimer()); 
    } 

    public void paintComponent(Graphics g){ 
     //tells ball what to do when it hits the sides 
     super.paintComponent(g); 
     r.fill(g); 
     b.fill(g); 
     gr.fill(g); 
     s.fill(g); 
     Font font = new Font("Courier", Font.PLAIN, 30); 
     g.setFont(font); 

     if (followMouse == true){ 
      timer.start(); 
      s.moveto(x, y); 
      g.drawString("Seed" ,x + 10, y - 10); 
     } 
     else if (followMouse == false){ 
      timer.stop(); 
      arraytimer.start(); 
      s.moveto(seedx, seedy); 
      int n = random.nextInt(3) + 1; 
      newx = pointx; 
      newy = pointy; 
      //1 = red 
      //2 = green 
      //3 = blue 
      if(dotcounter <= 14){ 
       if (n == 1){ 
        pointx = (newx + redx)/2; 
        pointy = (newy + redy)/2; 
        p[dotcounter] = new Point(pointx, pointy, Color.WHITE); 
       } 
       else if (n == 2){ 
        pointx = (newx + greenx)/2; 
        pointy = (newy + greeny)/2; 
        p[dotcounter] = new Point(pointx, pointy, Color.WHITE); 
       } 
       else if (n == 3){ 
        pointx = (newx + bluex)/2; 
        pointy = (newy + bluey)/2; 
        p[dotcounter] = new Point(pointx, pointy, Color.WHITE); 
       } 
      } 
      else if (dotcounter >= 15 && dotcounter < 10000){ 
       if (n == 1){ 
        pointx = (newx + redx)/2; 
        pointy = (newy + redy)/2; 
        p[dotcounter] = new Point(pointx, pointy, Color.RED); 
       } 
       else if (n == 2){ 
        pointx = (newx + greenx)/2; 
        pointy = (newy + greeny)/2; 
        p[dotcounter] = new Point(pointx, pointy, Color.GREEN); 
       } 
       else if (n == 3){ 
        pointx = (newx + bluex)/2; 
        pointy = (newy + bluey)/2; 
        p[dotcounter] = new Point(pointx, pointy, Color.BLUE); 
       } 
      } 
      else{ 
       arraytimer.stop(); 
      } 
      for (i = 0; i < dotcounter; i++) 
      { 
       p[i].fill(g); 
      } 
     } 
     g.drawString(""+dotcounter, 600, 60); 
    } 

    @Override 
    public void mouseDragged(MouseEvent e) { 
     // TODO Auto-generated method stub 
    } 

    @Override 
    public void mouseMoved(MouseEvent e) { 
     x = e.getX(); 
     y = e.getY(); 
    } 

    @Override 
    public void mouseClicked(MouseEvent e) { 
     // TODO Auto-generated method stub 
    } 

    @Override 
    public void mouseEntered(MouseEvent e) { 
     // TODO Auto-generated method stub 
    } 

    @Override 
    public void mouseExited(MouseEvent e) { 
     // TODO Auto-generated method stub 
    } 

    @Override 
    public void mousePressed(MouseEvent e){ 
     if (followMouse == true){ 
      seedx = x; 
      seedy = y; 
      pointx = seedx; 
      pointy = seedy; 
      followMouse = false; 
     } 
     else{} 
    } 

    @Override 
    public void mouseReleased(MouseEvent e) { 
     // TODO Auto-generated method stub 
    } 

    private class MoveListener implements ActionListener{ 
     public void actionPerformed(ActionEvent e){ 
      repaint(); 
     } 
    } 
    private class ArrayTimer implements ActionListener{ 
     public void actionPerformed(ActionEvent e){ 
      dotcounter++; 
      repaint(); 
     } 
    } 
} 
class Seed{ 
    private int centerX, centerY, radius; 
    private Color color; 
    public Seed(int x, int y, Color thecolor){ 
     centerX = x; 
     centerY = y; 
     radius = 4; 
     color = thecolor; 
    } 

    public void fill(Graphics g){ 
     //fills circle 
     Color oldColor = g.getColor(); 
     g.setColor(color); 
     g.fillOval(centerX-radius, centerY-radius, radius*2, radius*2); 
     g.setColor(oldColor); 
    } 

    public void moveto(int xAmount, int yAmount){ 
     //Moves ball 
     centerX = xAmount; 
     centerY = yAmount; 
    } 
} 
class Red{ 
    private int centerX, centerY, radius; 
    private Color color; 
    public Red(int x, int y, Color thecolor){ 
     centerX = x; 
     centerY = y; 
     radius = 4; 
     color = thecolor; 
    } 

    public void fill(Graphics g){ 
     //fills circle 
     Color oldColor = g.getColor(); 
     g.setColor(color); 
     g.fillOval(centerX-radius, centerY-radius, radius*2, radius*2); 
     g.setColor(oldColor); 
    } 

    public void moveto(int xAmount, int yAmount){ 
     //Moves ball 
     centerX = xAmount; 
     centerY = yAmount; 
    } 
} 
class Blue{ 
    private int centerX, centerY, radius; 
    private Color color; 
    public Blue(int x, int y, Color thecolor){ 
     centerX = x; 
     centerY = y; 
     radius = 4; 
     color = thecolor; 
    } 

    public void fill(Graphics g){ 
     //fills circle 
     Color oldColor = g.getColor(); 
     g.setColor(color); 
     g.fillOval(centerX-radius, centerY-radius, radius*2, radius*2); 
     g.setColor(oldColor); 
    } 

    public void moveto(int xAmount, int yAmount){ 
     //Moves ball 
     centerX = xAmount; 
     centerY = yAmount; 
    } 
} 
class Green{ 
    private int centerX, centerY, radius; 
    private Color color; 
    public Green(int x, int y, Color thecolor){ 
     centerX = x; 
     centerY = y; 
     radius = 4; 
     color = thecolor; 
    } 

    public void fill(Graphics g){ 
     //fills circle 
     Color oldColor = g.getColor(); 
     g.setColor(color); 
     g.fillOval(centerX-radius, centerY-radius, radius*2, radius*2); 
     g.setColor(oldColor); 
    } 

    public void moveto(int xAmount, int yAmount){ 
     //Moves ball 
     centerX = xAmount; 
     centerY = yAmount; 
    } 
} 
class Point{ 
    private int centerX, centerY, radius; 
    private Color color; 
    public Point(int x, int y, Color thecolor){ 
     centerX = x; 
     centerY = y; 
     radius = 1; 
     color = thecolor; 
    } 

    public void fill(Graphics g){ 
     //fills circle 
     Color oldColor = g.getColor(); 
     g.setColor(color); 
     g.fillRect(centerX-radius, centerY-radius, radius, radius); 
     g.setColor(oldColor); 
    } 

    public void moveto(int xAmount, int yAmount){ 
     //Moves ball 
     centerX = xAmount; 
     centerY = yAmount; 
    } 
} 

Answer 1

退房Custom Painting Approaches两个常见的方式做到这一点：

1. 保留对象的列表，通过这个列表中的每个组件需要重新绘制的时间绘制和迭代
2. 绘制到一个BufferedImage，然后重新绘制图像。

听起来像第二种方法就是你需要的东西，如果你有第一种方法的性能问题。