在java中绘制的椭圆形图形的大小不会增加

Question

我正在使用Ovals和Graphics对象用java编写一个简单的游戏。它被称为病毒，其作用是这样的：中间有一个椭圆形，外面有六个椭圆形。这些外部椭圆的大小应该会增加，直到点击为止，当它们消失时，玩家会得到10分。如果一个椭圆接触到了中心椭圆，那么中心椭圆的健康状况就会下降。当它达到零时，游戏结束。我遇到的问题是外部椭圆的大小不会增加。为什么会发生这种情况？

这是我的代码：

package virus;

import java.awt.*;
import java.util.Random;
import javax.swing.JPanel;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
public class VirusGamePanel extends JPanel implements MouseListener{
    private static final long serialVersionUID = 1L;//serialVersionUID field
    Random colour = new Random();//the outside ovals will always be a random colour
    private int sizeX = 1;//the x size of the outside ovals 
    private int sizeY = 1;//the y size of the outside ovals
    int score = 0;
    static String scorestring = "Score: ";
    Color rand = new Color(colour.nextInt(255),colour.nextInt(255),colour.nextInt(255));//generate the random colour
    public void paint(Graphics g)
    {
        super.paint(g);
        g.setColor(Color.magenta);
        g.drawString(scorestring+score,275,250);
        g.setColor(Color.orange);
        g.drawOval(200,150,200,200);
        g.setColor(rand);
        g.drawOval(270,50,50,50);
        g.drawOval(100,100,50,50);
        g.drawOval(450,100,50,50);
        g.drawOval(100,400,50,50);
        g.drawOval(450,400,50,50);
        g.drawOval(275,450,50,50);
        g.fillOval(270,50,sizeX,sizeY);//these six ovals are supposed to increase in size
        g.fillOval(100,100,sizeX,sizeY);
        g.fillOval(450,100,sizeX,sizeY);
        g.fillOval(100,400,sizeX,sizeY);
        g.fillOval(450,400,sizeX,sizeY);
        g.fillOval(275,450,sizeX,sizeY);
        inc();
    }
    public static void main(String[] args) {
      JPanel panel = new VirusGamePanel();
      JFrame frame = new JFrame("Virus");
      frame.setSize(700, 700);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(panel);
      frame.setVisible(true);
    }
    private void inc()//increase the size of the ovals
    {
        for(int i = 0; i<25000; i++)
        {
            sizeX++;
            sizeY++;
            repaint();
        }
    }

带线程的新代码：

package virus;

import java.awt.*;
import java.util.Random;
import javax.swing.JPanel;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
public class VirusGamePanel extends JPanel implements MouseListener,Runnable{
    private static final long serialVersionUID = 1L;
    Random colour = new Random();
    private int sizeX = 1;
    private int sizeY = 1;
    int score = 0;
    Thread thr = new Thread();
    static String scorestring = "Score: ";
    Color rand = new Color(colour.nextInt(255),colour.nextInt(255),colour.nextInt(255));
    public void paint(Graphics g)
    {
        super.paint(g);
        thr.start();
        g.setColor(Color.magenta);
        g.drawString(scorestring+score,275,250);
        g.setColor(Color.orange);
        g.drawOval(200,150,200,200);
        g.setColor(rand);
        g.fillOval(270,50,sizeX,sizeY);
        g.fillOval(100,100,sizeX,sizeY);
        g.fillOval(450,100,sizeX,sizeY);
        g.fillOval(100,400,sizeX,sizeY);
        g.fillOval(450,400,sizeX,sizeY);
        g.fillOval(275,450,sizeX,sizeY);
        inc();
    }
    public static void main(String[] args) {}
    private void inc()
    {
        thr.run();
    }
    public void run(){
        for(int i = 0; i<25000; i++)
        {
            sizeX++;
            sizeY++;
            repaint();
            try
            {
                Thread.sleep(10);
            }
            catch(InterruptedException e)
            {
                e.printStackTrace();
            }
        }
    }

Answer 1

这对我有效：

public class VirusGamePanel extends JPanel{
    private static final long serialVersionUID = 1L;//serialVersionUID field
    Random colour = new Random();//the outside ovals will always be a random colour
    private int sizeX = 0;//the x size of the outside ovals 
    private int sizeY = 0;//the y size of the outside ovals
    int score = 0;
    static String scorestring = "Score: ";
    Color rand = new Color(colour.nextInt(255), colour.nextInt(255), colour.nextInt(255)); //generate the random colour
    public void paint(Graphics g)
    {
        super.paint(g);
        g.setColor(Color.magenta);
        g.drawString(scorestring+score,275,250);
        g.setColor(Color.orange);
        g.drawOval(200, 150, 200, 200);
        g.setColor(rand);
        g.fillOval(270 - sizeX / 2, 50 - sizeY / 2, sizeX, sizeY);//these six ovals are supposed to increase in size
        g.fillOval(100 - sizeX / 2,100 - sizeY / 2, sizeX, sizeY);
        g.fillOval(450 - sizeX / 2,100 - sizeY / 2, sizeX, sizeY);
        g.fillOval(100 - sizeX / 2,400 - sizeY / 2, sizeX, sizeY);
        g.fillOval(450 - sizeX / 2,400 - sizeY / 2, sizeX, sizeY);
        g.fillOval(275 - sizeX / 2,450 - sizeY / 2, sizeX, sizeY);
        inc();
    }
    public static void main(String[] args) {
      JPanel panel = new VirusGamePanel();
      JFrame frame = new JFrame("Virus");
      frame.setSize(700, 700);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(panel);
      frame.setVisible(true);
    }
    private void inc()//increase the size of the ovals
    {
            sizeX++;
            sizeY++;
            repaint();
    }
}

只是固定了椭圆的中心点，并在inc方法中删除了环。如果要绘制椭圆边界，只需添加参数与fillOval命令相同的drawOval命令即可。

编辑：

如果您想减缓增长过程，只需在paint方法的inc()调用之前添加以下内容：

try {
    Thread.sleep(100);
} catch (InterruptedException e) {
    e.printStackTrace();
}

Answer 2

您的代码是递归的。在inc（）中，您调用了重新绘制，它调用了VirusGamePanel.paint（），它调用inc（。。。

每次对paint（）的调用都会重新调用paint（（）方法。因此，不要在inc（）中循环，而是执行以下操作：

private void inc()// increase the size of the ovals
{
  sizeX++;
  sizeY++;
  repaint();
}     

Answer 3

 for(int i = 0; i<25000; i++)
    {
        sizeX++;
        sizeY++;
        repaint();
    }

您的计算机无法像cpu增加sizeX和sizeY那样快速地重新绘制。添加一些以毫秒为单位的等待时间（尤其是如果你画了一个像800x600这样的大区域）

 for(int i = 0; i<25000; i++)
    {
        sizeX++;
        sizeY++;
        repaint();
        try{ sleep(100);} catch(InterruptedException e){}
    }

但是，从另一个线程执行此操作！所以，你的应用程序。不会冻结。

这是10 FPS。但你尝试了2G FPS。你好。

下面是一个线程的示例。

class TEN_FPS extends Thread
{
    public void run()
    {
        while(working)
        {
             //calculations here
             repaint();
             try{sleep(100);}catch(InterruptedException e){}
        }
     }
 }

然后在主要方法：

working=true;
TEN_FPS.start();

当你完成这个程序：

working=false;

将释放您的守护进程线程。