将 JFrame 拖至屏幕顶部可自动最大化，向下拖动可恢复正常大小

Question

我想寻求有关以下代码的帮助。

目标：

每当我将 JFrame 拖到屏幕顶部时，我应该能够将其放大到全屏。同样，如果 JFrame 处于全屏模式，每当我向下拖动它时，它应该返回到正常模式，具体取决于最小尺寸参数。

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class DraggableFrame extends JFrame {
    private int posX = 0, posY = 0;
    private boolean isDraggingDown = false;

    public DraggableFrame() {
        // Initialize the JFrame
        setUndecorated(true);
        setSize(800, 600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);

        // Add mouse listener for dragging
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                posX = e.getX();
                posY = e.getY();
                isDraggingDown = false;
            }
        });

        addMouseMotionListener(new MouseAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {
                int x = e.getXOnScreen() - posX;
                int y = e.getYOnScreen() - posY;

                // Handle dragging while in full screen
                if (getExtendedState() == JFrame.MAXIMIZED_BOTH) {
                    if (y > 0 && !isDraggingDown) {
                        isDraggingDown = true;
                        setExtendedState(JFrame.NORMAL);
                        setSize(800, 600); // Restore to initial size
                        setLocation(x, y);
                    } else if (y <= 0 && !isDraggingDown) {
                        // If the frame is dragged to the top while maximized, do nothing
                        return;
                    }
                } else {
                    setLocation(x, y);

                    // Check if dragged to the top
                    if (getY() <= 0) {
                        // Enlarge window to fullscreen without covering taskbar
                        GraphicsEnvironment env = GraphicsEnvironment.getLocalGraphicsEnvironment();
                        GraphicsDevice device = env.getDefaultScreenDevice();

                        Rectangle screenBounds = device.getDefaultConfiguration().getBounds();
                        Insets screenInsets = Toolkit.getDefaultToolkit().getScreenInsets(device.getDefaultConfiguration());

                        int taskbarHeight = screenInsets.bottom;

                        setBounds(screenBounds.x, screenBounds.y, screenBounds.width, screenBounds.height - taskbarHeight);
                    }
                }
            }
        });

        // Restore to normal size if dragged down while in fullscreen
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseReleased(MouseEvent e) {
                if (getY() == 0 && getExtendedState() == JFrame.MAXIMIZED_BOTH) {
                    setExtendedState(JFrame.NORMAL);
                    setSize(800, 600); // Restore to initial size
                    setLocationRelativeTo(null);
                }
            }
        });
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            DraggableFrame frame = new DraggableFrame();
            frame.setVisible(true);
        });
    }
}

我尝试应用一些在互联网上找到的代码，但似乎没有一个能按我的预期工作。

我想要的是以下内容：

每当我将 JFrame 拖到屏幕顶部时，我应该能够将其放大到全屏。同样，如果 JFrame 处于全屏模式，每当我向下拖动它时，它应该返回到正常模式，具体取决于最小尺寸参数。

Answer 1

问题是这样的情况：

            // Handle dragging while in full screen
            if (getExtendedState() == JFrame.MAXIMIZED_BOTH) {

您永远不会将帧扩展状态设置为

JFrame.MAXIMIZED_BOTH

，因此该条件永远不会成立，并且您永远不会到达将帧切换回正常状态的代码。

由于将框架设置为

JFrame.MAXIMIZED_BOTH

会遮挡任务栏（您似乎想避免这种情况），因此当框架最大化时，您需要另一个指示。

您可以通过向

maximized

添加布尔字段

DraggableFrame

并在必要时进行调整来实现此目的：

public class DraggableFrame extends JFrame {
    private boolean maximized = false;

    // ...
        addMouseMotionListener(new MouseAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {
                int x = e.getXOnScreen() - posX;
                int y = e.getYOnScreen() - posY;

                // Handle dragging while in full screen
                if (maximized) {
                    if (y > 0 && !isDraggingDown) {
                        isDraggingDown = true;
                        setExtendedState(JFrame.NORMAL);
                        setSize(800, 600); // Restore to initial size
                        setLocation(x, y);
                        maximized = false;
                    } else if (y <= 0 && !isDraggingDown) {
                        // If the frame is dragged to the top while maximized, do nothing
                        return;
                    }
                } else {
                    setLocation(x, y);

                    // Check if dragged to the top
                    if (getY() <= 0) {
                        // Enlarge window to fullscreen without covering taskbar
                        GraphicsEnvironment env = GraphicsEnvironment.getLocalGraphicsEnvironment();
                        GraphicsDevice device = env.getDefaultScreenDevice();

                        Rectangle screenBounds = device.getDefaultConfiguration().getBounds();
                        Insets screenInsets = Toolkit.getDefaultToolkit().getScreenInsets(device.getDefaultConfiguration());

                        int taskbarHeight = screenInsets.bottom;

                        setBounds(screenBounds.x, screenBounds.y, screenBounds.width, screenBounds.height - taskbarHeight);
                        maximized = true;
                    }
                }
            }
        });

        // Restore to normal size if dragged down while in fullscreen
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseReleased(MouseEvent e) {
                if (getY() == 0 && maximized) {
                    setExtendedState(JFrame.NORMAL);
                    setSize(800, 600); // Restore to initial size
                    setLocationRelativeTo(null);
                    maximized = false;
                }
            }
        });
    }
    // ...
}

更好的是要么不使用未装饰的框架（因为它们与操作系统的窗口管理器一起工作），要么（如果您需要未装饰的框架，因为您想制作全屏游戏）使窗口从一开始就全屏.