Java Swing:用鼠标单击JPanel来绕圈 [英] Java Swing: Making a growing circle by mouse click on JPanel

问题描述

我是Java的初学者，这次我想通过查找代码示例并对其进行编辑(例如，从本网站进行编辑)来学习更多信息.我有一个JFrame，每次单击它(或更精确地说是JPanel)时，都会绘制一个圆圈，该圆圈将像水波纹一样向外扩展/扩展.每个圆都以一定的半径开始，并且在达到更大的半径时将被移除或重新绘制(我从10到200中选择了半径"r").我为此有两个程序，它们几乎可以工作，但是缺少一些东西.如果我是正确的话，我可能也知道他们的问题是什么，但我不知道如何解决它们:

I'm a beginner in Java and this time I'm trying to learn more by finding code examples and editing them, for example from this website. I have a JFrame and each time it (or more precise the JPanel in it) is clicked on, a circle is drawn which will grow/expand outwards like a water ripple. Each circle starts with a certain radius and will be removed or redrawn when reaching a bigger radius (I chose radius "r" from 10 to 200). I have two programs for this which almost work but are missing something. If I'm correct, I might also know what their problems are but I can't figure out how to solve them:

一个生成的圆形，但是无论它们何时生成，它们都具有相同的大小，因为我找不到如何将半径分配给单个圆形.该代码改编自此处:

One generates growing circles but all of them have the same size, no matter when they're generated, since I can't find out how to assign the radius to a single circle. The code is adapted from here:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;

public class Ripples extends JPanel implements ActionListener{

    public int r = 10;
    private ArrayList<Point> p;
    
    public Ripples() {
        p = new ArrayList<>();
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                p.add(new Point(e.getX(), e.getY()));
            }
        });
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setColor(Color.CYAN);
        for (Point pt : p) {
            g2.drawOval(pt.x-r, pt.y-r, 2*r, 2*r);
        }
    }
    
        
    @Override
    public void actionPerformed(ActionEvent evt) {
        if(r<200){
            r++;
        } else {
            r = 10;
        }
        repaint();
    }
    
    public static void Gui() {
        JFrame f = new JFrame();
        Ripples p = new Ripples();
        p.setBackground(Color.WHITE);
        f.setContentPane(p);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setSize(500,300);
        f.setVisible(true);
        Timer t = new Timer(20,p);
        t.start();
    }

    public static void main(String[] args) {
        Gui();
    }

}

另一个程序(我忘记了我从哪里得到的)有不同半径的圆，具体取决于它们生成的时间，但是圆是闪烁的"，因为据我所知，它们都是在同时，因为代码未像上面的代码那样包含用于分别存储和更新每个圆的数组:

The other program(I've forgotten where I got it from) has circles with different radii depending on when they were generated, however the circles "flicker", because -as far as I understand- they are all processed at the same time, because the code doesn't include an Array to store and update each circle individually like the one above does:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;

public class Ripples extends JPanel { 
    int x,y;
    int r = 10;
    
    public Ripples(int x, int y) {
        this.x = x;
        this.y = y; 
        Timer t = new Timer(20, new ActionListener() { 
            @Override
            public void actionPerformed(ActionEvent e) { 
                if (r<200) { 
                    r++;
                } else {
                    r=10;
                }
                revalidate();
                repaint();
            }
        }); 
        t.start(); 
    }

    @Override
    public void paintComponent(Graphics g) { 
        super.paintComponent(g);
        g.setColor(Color.CYAN);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.drawOval(x-r,y-r,2*r,2*r);
    }
    
    public static void Gui() {
        JFrame f = new JFrame("Water Ripples");
        JPanel p0 = new JPanel();
        p0.setBackground(Color.WHITE);
        f.add(p0);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setBounds(100,100,600,500);
        f.setVisible(true);
        f.addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) { 
                Ripples rG = new Ripples(e.getX(), e.getY());
                rG.setBackground(Color.WHITE);
                f.add(rG); 
            }
         });
    }

    public static void main(String[] args) {
        Gui();
    }
    
}

那么我该如何解决这个问题，以便使圈子彼此独立发展?我更希望为上层代码提供解决方案/改进/提示，因为我认为其结构要比第二层更好.另外，我很抱歉没有将代码拆分为更多的类，并且可能不遵循命名约定.感谢您的帮助，非常感谢！

So how can I solve this so that I get the circles growing independent from each other? I'd prefer a solution/improvement/hint for the upper code because I think its structured better than the second one. Also, I apologize for not splitting the code into more classes and for possibly not sticking to naming conventions. I appreciate your help, thank you very much!

推荐答案

我在您的涟漪图代码中添加了 Circle 类.这样， ActionListener 可以独立对待每个圆.

I added a Circle class to your Ripples code. This allows the ActionListener to treat each circle independently.

我通过调用 SwingUtilities invokeLater 方法启动了GUI.此方法确保在事件调度线程上创建并执行Swing组件..

I started the GUI with a call to the SwingUtilities invokeLater method. This method ensures that the Swing components are created and executed on the Event Dispatch Thread.

这是代码.

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class Ripples extends JPanel implements ActionListener {

    private List<Circle> circles;

    public Ripples() {
        circles = new ArrayList<>();
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent event) {
                circles.add(new Circle(event.getPoint()));
            }
        });
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setColor(Color.CYAN);
        g2.setStroke(new BasicStroke(3f));
        
        for (Circle circle : circles) {
            Point p = circle.getCenter();
            int radius = circle.getRadius();
            g2.drawOval(p.x - radius, p.y - radius,
                    2 * radius, 2 * radius);
        }
    }

    @Override
    public void actionPerformed(ActionEvent evt) {
        for (Circle circle : circles) {
            circle.incrementRadius();
        }
        repaint();
    }

    public static void createGUI() {
        JFrame f = new JFrame("Ripples");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Ripples p = new Ripples();
        p.setBackground(Color.WHITE);
        p.setPreferredSize(new Dimension(500, 500));
        f.setContentPane(p);

        f.pack();
        f.setLocationByPlatform(true);
        f.setVisible(true);

        Timer t = new Timer(20, p);
        t.start();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                createGUI();
            }
        });
    }

    public class Circle {

        private int radius;

        private final Point center;

        public Circle(Point center) {
            this.center = center;
            this.radius = 10;
        }

        public void incrementRadius() {
            radius += 1;
            radius = (radius > 200) ? 10 : radius;
        }

        public int getRadius() {
            return radius;
        }

        public Point getCenter() {
            return center;
        }

    }

}

编辑后添加:

我重新制作了 Ripples 类代码以分离问题.我创建了一个 DrawingPanel 类来保存绘图面板，一个 RipplesListener 类来保存 MouseAdapter 代码，一个 Animation 用于保存运行圆形动画的 Runnable 的类，用于保存 Circle 的 List 的 RipplesModel 类实例，最后是 Circle 类.

I reworked the Ripples class code to separate the concerns. I created a DrawingPanel class to hold the drawing panel, a RipplesListener class to hold the MouseAdapter code, an Animation class to hold the Runnable that runs the animation of the circles, a RipplesModel class to hold the List of Circle instances, and finally, the Circle class.

本来可以为动画使用Swing Timer ，但是我对创建和运行自己的动画线程更为熟悉.

I could have used a Swing Timer for the animation, but I'm more familiar with creating and running my own animation thread.

是的，此代码比原始示例更复杂.此处使用的编码样式可用于更大，更复杂的Swing GUI开发.

Yes, this code is more complicated than the original example. The coding style used here can be carried into larger, more complex Swing GUI development.

这是修改后的代码.我希望这是一个更好的例子.

Here's the revised code. I hope it's a better example.

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Ripples implements Runnable {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Ripples());
    }

    private Animation animation;

    private DrawingPanel drawingPanel;

    private RipplesModel model;

    public Ripples() {
        model = new RipplesModel();
    }

    @Override
    public void run() {
        JFrame frame = new JFrame("Ripples");
        frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent event) {
                stopAnimation();
                frame.dispose();
                System.exit(0);
            }
        });

        drawingPanel = new DrawingPanel(model);
        frame.add(drawingPanel, BorderLayout.CENTER);

        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);

        animation = new Animation(this, model);
        new Thread(animation).start();
    }

    public void repaint() {
        drawingPanel.repaint();
    }

    private void stopAnimation() {
        if (animation != null) {
            animation.setRunning(false);
        }
    }

    public class DrawingPanel extends JPanel {

        private static final long serialVersionUID = 1L;

        private RipplesModel model;

        public DrawingPanel(RipplesModel model) {
            this.model = model;
            setBackground(Color.WHITE);
            setPreferredSize(new Dimension(500, 500));
            addMouseListener(new RipplesListener(model));
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);

            Graphics2D g2 = (Graphics2D) g;
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON);
            g2.setStroke(new BasicStroke(3f));

            List<Circle> circles = model.getCircles();
            for (Circle circle : circles) {
                Point p = circle.getCenter();
                int radius = circle.getRadius();
                g2.setColor(circle.getColor());
                g2.drawOval(p.x - radius, p.y - radius,
                        2 * radius, 2 * radius);
            }
        }

    }

    public class RipplesListener extends MouseAdapter {

        private RipplesModel model;

        public RipplesListener(RipplesModel model) {
            this.model = model;
        }

        @Override
        public void mousePressed(MouseEvent event) {
            model.addCircle(new Circle(event.getPoint(),
                    createColor()));
        }

        private Color createColor() {
            Random random = new Random();
            int r = random.nextInt(255);
            int g = random.nextInt(255);
            int b = random.nextInt(255);
            return new Color(r, g, b);
        }
    }

    public class Animation implements Runnable {

        private volatile boolean running;

        private Ripples frame;

        private RipplesModel model;

        public Animation(Ripples frame, RipplesModel model) {
            this.frame = frame;
            this.model = model;
            this.running = true;
        }

        @Override
        public void run() {
            while (running) {
                sleep(20L);
                incrementRadius();
            }
        }

        private void incrementRadius() {
            List<Circle> circles = model.getCircles();
            for (Circle circle : circles) {
                circle.incrementRadius();
            }
            repaint();
        }

        private void sleep(long delay) {
            try {
                Thread.sleep(delay);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        private void repaint() {
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    frame.repaint();
                }
            });
        }

        public synchronized void setRunning(boolean running) {
            this.running = running;
        }

    }

    public class RipplesModel {

        private List<Circle> circles;

        public RipplesModel() {
            this.circles = new ArrayList<>();
        }

        public void addCircle(Circle circle) {
            this.circles.add(circle);
        }

        public List<Circle> getCircles() {
            return circles;
        }

    }

    public class Circle {

        private int radius;

        private final Color color;

        private final Point center;

        public Circle(Point center, Color color) {
            this.center = center;
            this.color = color;
            this.radius = 10;
        }

        public void incrementRadius() {
            radius = (++radius > 200) ? 10 : radius;
        }

        public Color getColor() {
            return color;
        }

        public int getRadius() {
            return radius;
        }

        public Point getCenter() {
            return center;
        }

    }

}

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