Java AWT：JFrame SetLocation 不应移出屏幕

Question

使用四个按钮，window 应在四个方向（北、南、东、西）移动，并且 window 不应离开屏幕。这在北部和西部很顺利，但不幸的是在其他方向却行不通。我猜错误是在 getEffectiveScreenArea 方法中，但我不确定。

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

public class MoveWindowGUI extends JFrame {
    private JButton moveUp, moveDown, moveLeft, moveRight;
    private int x, y;
    
    public MoveWindowGUI(String title) {
        super(title);
        this.initializeButtons();
        this.prepareWindow();
        this.addActionListener();
        pack();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
    
    private void initializeButtons() {
        this.moveUp = new JButton("U");
        this.moveDown = new JButton("D");
        this.moveLeft = new JButton("L");
        this.moveRight = new JButton("R");
    }
    
    private void prepareWindow() {
        setLayout(new BorderLayout(25, 25));
        this.addComponents();
        this.centerWindow();
        setSize(300, 300);
    }
    
    private void centerWindow() {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        Dimension windowSize = getSize();
        int centralWidth = (screenSize.width - windowSize.width) / 2;
        int centralHeight = (screenSize.height - windowSize.height) / 2;
        setLocation(centralWidth, centralHeight);
    }
    
    private void addComponents() {
        add(this.moveUp, BorderLayout.NORTH);
        add(this.moveDown, BorderLayout.SOUTH);
        add(this.moveLeft, BorderLayout.WEST);
        add(this.moveRight, BorderLayout.EAST);
    }
    
    private void addActionListener() {
        ActionListener listener = new WindowActionListener();
        moveUp.addActionListener(listener);
        moveDown.addActionListener(listener);
        moveLeft.addActionListener(listener);
        moveRight.addActionListener(listener);
    }
    
    class WindowActionListener implements ActionListener {  
        @Override
        public void actionPerformed(ActionEvent e) {
            String command = e.getActionCommand();
            if (command.equals("U")) {
                y -= 10;
            } else if (command.equals("D")) {
                y += 10;
            } else if (command.equals("L")) {
                x -= 10;
            } else if (command.equals("R")) {
                x += 10;
            }
            this.refreshWindow();
        }
        
        private void refreshWindow() {
            Point lastLocation = getLocation();
            Rectangle effectiveScreenArea = getEffectiveScreenArea();
            int newX = lastLocation.x + x;
            int newY = lastLocation.y + y;
            if (newX < effectiveScreenArea.x) {
                newX = effectiveScreenArea.x;
            } else if (newY < effectiveScreenArea.y) {
                newY = effectiveScreenArea.y;
            } else if (newX >= effectiveScreenArea.width) {
                newX = effectiveScreenArea.width;
            } else if (newY >= effectiveScreenArea.height) {
                newY = effectiveScreenArea.height;
            }
            setLocation(newX, newY);
            this.resetHeightAndWitdhLocally();
            pack();
        }
        
        public Rectangle getEffectiveScreenArea() {
            int minX = 0, minY = 0, maxX = 0, maxY = 0;
            GraphicsEnvironment environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
            int screenDevices = environment.getScreenDevices().length;
            for(GraphicsDevice device : environment.getScreenDevices()) {
                Rectangle bounds = device.getDefaultConfiguration().getBounds();
                minX = Math.min(minX, bounds.x);
                minY = Math.min(minY, bounds.y);
                maxX = Math.max(maxX, bounds.x + bounds.width);
                maxY = Math.max(maxY, bounds.y + bounds.height);
            }
            return new Rectangle(minX, minY, (maxX - minX) / screenDevices, (maxY - minY) / screenDevices);
        }
        
        /*
        private Rectangle getEffectiveScreenArea() {
            GraphicsConfiguration graphicsConfiguration = getGraphicsConfiguration();
            Rectangle bounds = graphicsConfiguration.getBounds();
            Insets screenInsets = Toolkit.getDefaultToolkit().getScreenInsets(graphicsConfiguration);
            Rectangle effectiveScreenArea = new Rectangle();
            effectiveScreenArea.x = bounds.x + screenInsets.left;
            effectiveScreenArea.y = bounds.y + screenInsets.top;
            effectiveScreenArea.height = bounds.height + screenInsets.top - screenInsets.bottom;
            effectiveScreenArea.width = bounds.width - screenInsets.left - screenInsets.right;
            return effectiveScreenArea;
        }
        */
        
        private void resetHeightAndWitdhLocally() {
            x = 0;
            y = 0;
        }
    }
}

Answer 1

我拿了你的代码并做了一些修改。这是我创建的 GUI。

我把 JButtons 放在了 JPanel 上。然后我将 JPanel 放在 JFrame 上。通常，最好将 Swing 组件放在 JPanel 上，而不是直接放在 JFrame.

上

我清理了 WindowActionListener class.

这是完整的可运行代码。我将 WindowActionListener class 设为内部 class 这样我就可以 post 将这段代码作为一个块。

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class MoveWindowGUI implements Runnable {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new MoveWindowGUI());
    }
    
    private JFrame frame;

    @Override
    public void run() {
        frame = new JFrame("Move Window GUI");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        frame.add(createMainPanel(), BorderLayout.CENTER);
        
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }
    
    private JPanel createMainPanel() {
        JPanel panel = new JPanel(new BorderLayout());
        panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));

        WindowActionListener listener = new WindowActionListener(this);

        JButton upButton = new JButton("Up");
        upButton.addActionListener(listener);
        panel.add(upButton, BorderLayout.NORTH);
        
        JButton downButton = new JButton("Down");
        downButton.addActionListener(listener);
        panel.add(downButton, BorderLayout.SOUTH);
        
        JButton leftButton = new JButton("Left");
        leftButton.addActionListener(listener);
        panel.add(leftButton, BorderLayout.WEST);
        
        JButton rightButton = new JButton("Right");
        rightButton.addActionListener(listener);
        panel.add(rightButton, BorderLayout.EAST);
        
        Dimension d = panel.getPreferredSize();
        d.width = 300;
        panel.setPreferredSize(d);

        return panel;
    }
    
    public JFrame getFrame() {
        return frame;
    }
    
    public class WindowActionListener implements ActionListener {
        
        private final MoveWindowGUI view;

        public WindowActionListener(MoveWindowGUI view) {
            this.view = view;
        }

        @Override
        public void actionPerformed(ActionEvent event) {
            String command = event.getActionCommand();
            int increment = 100;
            switch (command) {
            case "Up":
                refreshWindow(0, -increment);
                break;
            case "Down":
                refreshWindow(0, increment);
                break;
            case "Left":
                refreshWindow(-increment, 0);
                break;
            case "Right":
                refreshWindow(increment, 0);
                break;
            }
        }
        
        private void refreshWindow(int deltaX, int deltaY) {
            Rectangle frameArea = view.getFrame().getBounds();
            Rectangle screenArea = getEffectiveScreenArea();
            
            int x = frameArea.x;
            int y = frameArea.y;
            int minX = screenArea.x;
            int minY = screenArea.y;
            int maxX = screenArea.width - frameArea.width;
            int maxY = screenArea.height - frameArea.height;
            
            x += deltaX;
            y += deltaY;
            
            x = Math.max(minX, x);
            x = Math.min(maxX, x);
            
            y = Math.max(minY, y);
            y = Math.min(maxY, y);
            
            view.getFrame().setBounds(new Rectangle(x, y, frameArea.width, frameArea.height));
        }
        
        private Rectangle getEffectiveScreenArea() {
            int minX = 0, minY = 0, maxX = 0, maxY = 0;
            GraphicsEnvironment environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
            int screenDevices = environment.getScreenDevices().length;
            for (GraphicsDevice device : environment.getScreenDevices()) {
                Rectangle bounds = device.getDefaultConfiguration().getBounds();
                minX = Math.min(minX, bounds.x);
                minY = Math.min(minY, bounds.y);
                maxX = Math.max(maxX, bounds.x + bounds.width);
                maxY = Math.max(maxY, bounds.y + bounds.height);
            }
            return new Rectangle(minX, minY, (maxX - minX) / screenDevices, 
                    (maxY - minY) / screenDevices);
        }
        
    }

}

Java AWT：JFrame SetLocation 不应移出屏幕

Java AWT: JFrame SetLocation should not move outside the screen

java

awt