拖动和调整未装饰的 JFrame 大小

您可以查看Rob Camick先生的ConspartmentResizer类。非常简单明了，使用起来很简单。

只需实例化并使用如下内容注册帧：ComponentResizer

JFrame frame = new JFrame();
ComponentResizer cr = new ComponentResizer();
cr.registerComponent(frame);
cr.setSnapSize(new Dimension(10, 10));
cr.setMaximumSize(new Dimension(...));
cr.setMinimumSize(new Dimension(...));

下面是使用该类的完整示例

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

public class UndecoratedExample {

    private JFrame frame = new JFrame();

    class MainPanel extends JPanel {

        public MainPanel() {
            setBackground(Color.gray);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(400, 400);
        }
    }

    class BorderPanel extends JPanel {

        private JLabel label;
        int pX, pY;

        public BorderPanel() {
            label = new JLabel(" X ");
            label.setOpaque(true);
            label.setBackground(Color.RED);
            label.setForeground(Color.WHITE);

            setBackground(Color.black);
            setLayout(new FlowLayout(FlowLayout.RIGHT));

            add(label);

            label.addMouseListener(new MouseAdapter() {
                public void mouseReleased(MouseEvent e) {
                    System.exit(0);
                }
            });
            addMouseListener(new MouseAdapter() {
                public void mousePressed(MouseEvent me) {
                    // Get x,y and store them
                    pX = me.getX();
                    pY = me.getY();

                }

                 public void mouseDragged(MouseEvent me) {

                    frame.setLocation(frame.getLocation().x + me.getX() - pX,
                            frame.getLocation().y + me.getY() - pY);
                }
            });

            addMouseMotionListener(new MouseMotionAdapter() {
                public void mouseDragged(MouseEvent me) {

                    frame.setLocation(frame.getLocation().x + me.getX() - pX,
                            frame.getLocation().y + me.getY() - pY);
                }
            });
        }
    }

    class OutsidePanel extends JPanel {

        public OutsidePanel() {
            setLayout(new BorderLayout());
            add(new MainPanel(), BorderLayout.CENTER);
            add(new BorderPanel(), BorderLayout.PAGE_START);
            setBorder(new LineBorder(Color.BLACK, 5));
        }
    }

    private void createAnsShowGui() {
        ComponentResizer cr = new ComponentResizer();
        cr.setMinimumSize(new Dimension(300, 300));
        cr.setMaximumSize(new Dimension(800, 600));
        cr.registerComponent(frame);
        cr.setSnapSize(new Dimension(10, 10));
        frame.setUndecorated(true);
        frame.add(new OutsidePanel());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new UndecoratedExample().createAnsShowGui();
            }
        });
    }
}

我最近为此构建了自己的原型。也许你会发现这很有用。

它使用2个不同的组件，一个在另一个之上。与 Rob Camick 的 ComponentResizer 不同，这是受其启发的，设置为 JFrame 中组件的鼠标侦听器将正常工作。您不会让 JFrame 捕获所有鼠标事件，因此将侦听器附加到 JFrame 中的组件变得毫无用处。它仅在必须显示双向箭头的时间和位置捕获鼠标事件。

关键是顶部组件中的此方法：

@Override
public boolean contains(int x, int y) {
    return x < insets.left || y < insets.top
            || getHeight() - y < insets.bottom
            || getWidth() - x < insets.right;
}

代码如下：

import java.awt.Component;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;

public class BackgroundComponentDragger implements MouseMotionListener {

    private Component controlledComponent;

    /*
     * Point where cursor was last clicked.
     */
    private Point originPoint;

    public BackgroundComponentDragger(Component component) {
        this.controlledComponent = component;
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        Point currentFramePosition = controlledComponent.getLocation();
        Point newFramePosition = new Point(currentFramePosition.x + e.getX()
                - originPoint.x, currentFramePosition.y + e.getY() - originPoint.y);
        controlledComponent.setLocation(newFramePosition);
    }

    @Override
    public void mouseMoved(MouseEvent e) {
        originPoint = e.getPoint();
    }
}



import java.awt.Component;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.util.HashMap;
import java.util.Map;

public class ComponentBorderDragger implements MouseMotionListener {

    private Component controlledComponent;

    private byte direction;
    protected static final byte NORTH = 1;
    protected static final byte WEST = 2;
    protected static final byte SOUTH = 4;
    protected static final byte EAST = 8;

    private Cursor sourceCursor;

    private static Map<Byte, Integer> cursors = new HashMap<Byte, Integer>();
    {
        cursors.put((byte) 1, Cursor.N_RESIZE_CURSOR);
        cursors.put((byte) 2, Cursor.W_RESIZE_CURSOR);
        cursors.put((byte) 4, Cursor.S_RESIZE_CURSOR);
        cursors.put((byte) 8, Cursor.E_RESIZE_CURSOR);
        cursors.put((byte) 3, Cursor.NW_RESIZE_CURSOR);
        cursors.put((byte) 9, Cursor.NE_RESIZE_CURSOR);
        cursors.put((byte) 6, Cursor.SW_RESIZE_CURSOR);
        cursors.put((byte) 12, Cursor.SE_RESIZE_CURSOR);
    }

    private Insets dragInsets;
    private Dimension minSize;

    private Point basePoint;

    public ComponentBorderDragger(Component controlledComponent, Insets dragInsets,
            Dimension minSize) {
        super();
        this.controlledComponent = controlledComponent;
        this.dragInsets = dragInsets;
        this.minSize = minSize;
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        if (direction == 0) {
            return;
        }

        Point newPoint = e.getPoint();
        int x, y, width, height, newBasePointX, newBasePointY;
        x = controlledComponent.getX();
        y = controlledComponent.getY();
        width = controlledComponent.getWidth();
        height = controlledComponent.getHeight();
        newBasePointX = newPoint.x;
        newBasePointY = newPoint.y;

        if ((direction & EAST) == EAST) {
            int newWidth;
            newWidth = Math.max(minSize.width, width + newPoint.x
                    - basePoint.x);
            width = newWidth;
        }
        if ((direction & SOUTH) == SOUTH) {
            int novoAlto;
            novoAlto = Math.max(minSize.height, height + newPoint.y
                    - basePoint.y);
            height = novoAlto;
        }
        if ((direction & WEST) == WEST) {
            int newWidth, newX;
            newWidth = Math.max(minSize.width, width - newPoint.x
                    + basePoint.x);
            newX = Math.min(x + width - minSize.width, x + newPoint.x
                    - basePoint.x);

            // Changing coordenates of new base point to refer to the new component position
            newBasePointX -= newX - x;
            x = newX;
            width = newWidth;
        }
        if ((direction & NORTH) == NORTH) {
            int newHeigth, newY;
            newHeigth = Math.max(minSize.height, height - newPoint.y
                    + basePoint.y);
            newY = Math.min(y + height - minSize.height, y + newPoint.y
                    - basePoint.y);
            // Changing coordenates of new base point to refer to the new component position
            newBasePointY -= newY - y;
            y = newY;
            height = newHeigth;
        }
        controlledComponent.setBounds(x, y, width, height);
        basePoint = new Point(newBasePointX, newBasePointY);
    }

    @Override
    public void mouseMoved(MouseEvent e) {
        Component originator = e.getComponent();
        if (direction == 0) {
            sourceCursor = originator.getCursor();
        }
        calculateDirection(e.getPoint(), e.getComponent().getSize());
        setCursor(e.getComponent());
        basePoint = e.getPoint();
    }

    private void setCursor(Component component) {
        if (direction == 0) {
            component.setCursor(sourceCursor);
        } else {
            int cursorType = cursors.get(direction);
            Cursor cursor = Cursor.getPredefinedCursor(cursorType);
            component.setCursor(cursor);
        }
    }

    private void calculateDirection(Point point, Dimension componentSize) {
        direction = 0;
        if (point.x < dragInsets.left) {
            direction |= WEST;
        }
        if (point.y < dragInsets.top) {
            direction |= NORTH;
        }
        if (point.x > componentSize.width - dragInsets.right) {
            direction |= EAST;
        }
        if (point.y > componentSize.height - dragInsets.bottom) {
            direction |= SOUTH;
        }
    }
}


import java.awt.Insets;

import javax.swing.JComponent;

public class FrameComponent extends JComponent {

    private static final long serialVersionUID = 3383070502274306213L;

    private Insets insets;

    @Override
    public boolean contains(int x, int y) {
        return x < insets.left || y < insets.top || getHeight() - y < insets.bottom || getWidth() - x < insets.right;
    }

    public FrameComponent(Insets insets) {
        this.insets = insets;
    }
}


import java.awt.Dimension;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;

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

public class GUI {

    private JFrame compoundFrame;
    private JPanel backgroundPanel;

    Dimension gUISize = new Dimension(400, 400);

    public GUI() {
        buildResizeableFrame();
    }

    public void activate() {
        compoundFrame.setVisible(true);
    }

    private void buildResizeableFrame() {
        compoundFrame = new JFrame();
        FrameComponent frame = new FrameComponent(new Insets(5, 5, 5, 5));
        backgroundPanel = new JPanel();
        compoundFrame.setLayout(null);
        compoundFrame.add(frame);
        compoundFrame.add(backgroundPanel);
        setFrameSizeController(frame, backgroundPanel);
        setFrameController(frame);
        setBackgroundPanelController(backgroundPanel);
        Dimension dimPant = Toolkit.getDefaultToolkit().getScreenSize();
        compoundFrame.setBounds(dimPant.width / 4, dimPant.height / 4, dimPant.width / 2, dimPant.height / 2);
        compoundFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        compoundFrame.setUndecorated(true);
    }

    private void setFrameSizeController(FrameComponent frame, JPanel panel) {
        compoundFrame.addComponentListener(new ComponentAdapter() {
            @Override
            public void componentResized(ComponentEvent e) {
                Dimension sizeIn = ((JFrame) e.getComponent()).getContentPane().getSize();
                frame.setSize(sizeIn);
                panel.setSize(sizeIn);
            }
        });
    }

    private void setFrameController(FrameComponent frame) {
        ComponentBorderDragger controller = new ComponentBorderDragger(compoundFrame,
                new Insets(5, 5, 5, 5), new Dimension(10, 10));
        frame.addMouseMotionListener(controller);
    }

    private void setBackgroundPanelController(JPanel panel) {
        panel.addMouseMotionListener(new BackgroundComponentDragger(compoundFrame));
    }

    public static void main(String[] args) {
        new GUI().activate();
    }
}

注意：此代码设置一个空布局管理器和一个容器侦听器，以便在需要时调整内部组件的大小。不鼓励这种做法。应将此逻辑移动到自定义布局管理器。