java - 透明 JDesktopPane

Question

我想将 JDesktopPane 设置为透明，并允许我单击下面的内容(例如桌面图标等)。内部框架应保持不透明，并且能够像当前一样在屏幕周围重新定位。有什么想法吗？

    package test1;

    import java.awt.BorderLayout;
    import java.awt.Color;
    import javax.swing.JDesktopPane;
    import javax.swing.JFrame;
    import javax.swing.JInternalFrame;
    import javax.swing.JLabel;


    public class Test1 {

    public static void main(String[] args) {

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setUndecorated(true);


    JDesktopPane desktop = new JDesktopPane();
    JInternalFrame internalFrame = new JInternalFrame("Title", false, true, false, true);
    desktop.setBackground(Color.RED);  
    //desktop.setBackground(new Color(1.0f,1.0f,1.0f,0.0f));
    desktop.add(internalFrame);
    internalFrame.setBounds(25, 25, 200, 100);
    internalFrame.setVisible(true);
    frame.add(desktop, BorderLayout.CENTER);
    frame.setExtendedState(JFrame.MAXIMIZED_BOTH); 
    frame.setVisible(true);

    }

}

Answer 1

第 1 部分半透明 JInternalFrame

创建半透明组件比仅将背景颜色设置为基于 alpha 的值更复杂。

Swing 只知道如何绘制不透明或完全透明的组件，API 也经过了优化，如果它更新不透明组件，它不会更新组件后面的父级区域。使用基于 alpha 的颜色会产生各种令人讨厌的绘画伪影

相反，您需要“伪造”它。这涉及将组件设置为完全覆盖组件的 Paint 方法并使用 AlphaComposite 生成半透明效果(通常我会使用 PaintComponent > 方法，但您必须记住这不会影响子组件)

import java.awt.AlphaComposite;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Main {

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

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    try {
                        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                    } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                        ex.printStackTrace();
                    }

                    JDesktopPane dp = new BackgroundDesktopPane();

                    BufferedImage img = ImageIO.read(new File("C:\\Users\\shane\\Dropbox\\Ponies\\SmallPony.png"));

                    TransparentInternalFrame iframe = new TransparentInternalFrame("Banana", true, true, true, true);
                    iframe.setLocation(10, 10);
                    iframe.add(new JLabel(new ImageIcon(img)));
                    iframe.pack();
                    iframe.setVisible(true);

                    dp.add(iframe);


                    JFrame frame = new JFrame("Testing");
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.add(dp);
                    frame.pack();
                    frame.setLocationRelativeTo(null);
                    frame.setVisible(true);
                } catch (IOException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        });
    }

    public class TransparentInternalFrame extends JInternalFrame {

        public TransparentInternalFrame() {
            super();
        }

        public TransparentInternalFrame(String title) {
            super(title);
        }

        public TransparentInternalFrame(String title, boolean resizable) {
            super(title, resizable);
        }

        public TransparentInternalFrame(String title, boolean resizable, boolean closable) {
            super(title, resizable, closable);
        }

        public TransparentInternalFrame(String title, boolean resizable, boolean closable, boolean maximizable) {
            super(title, resizable, closable, maximizable);
        }

        public TransparentInternalFrame(String title, boolean resizable, boolean closable, boolean maximizable, boolean iconifiable) {
            super(title, resizable, closable, maximizable, iconifiable);
        }

        @Override
        public void paint(Graphics g) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setComposite(AlphaComposite.SrcOver.derive(0.25f));
            super.paint(g2d);
            g2d.dispose();
        }

    }

    public class BackgroundDesktopPane extends JDesktopPane {

        private BufferedImage background;

        public BackgroundDesktopPane() throws IOException {
            background = ImageIO.read(new File("C:\\Users\\shane\\Dropbox\\Ponies\\800px-Rainbow_Dash_flying_past_1_S2E16.png"));
        }

        @Override
        public Dimension getPreferredSize() {
            return background == null ? super.getPreferredSize() : new Dimension(background.getWidth(), background.getHeight()); 
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (background != null) {
                Graphics2D g2d = (Graphics2D) g.create();
                int x = (getWidth() - background.getWidth()) / 2;
                int y = (getHeight() - background.getHeight()) / 2;
                g2d.drawImage(background, x, y, this);
                g2d.dispose();
            }
        }



    }

}

第 2 部分点击...

提供单击组件的能力要困难得多，并且如果添加支持鼠标事件的组件，就会变得更加困难。以下将允许鼠标事件“穿过”组件(框架板除外)，但内部框架中响应鼠标事件的任何组件都会阻止其工作。

public class TransparentInternalFrame extends JInternalFrame {

    public TransparentInternalFrame() {
        super();
        setOpaque(false);
        init();
    }

    public TransparentInternalFrame(String title) {
        super(title);
        setOpaque(false);
        init();
    }

    public TransparentInternalFrame(String title, boolean resizable) {
        super(title, resizable);
        setOpaque(false);
        init();
    }

    public TransparentInternalFrame(String title, boolean resizable, boolean closable) {
        super(title, resizable, closable);
        setOpaque(false);
        init();
    }

    public TransparentInternalFrame(String title, boolean resizable, boolean closable, boolean maximizable) {
        super(title, resizable, closable, maximizable);
        setOpaque(false);
        init();
    }

    public TransparentInternalFrame(String title, boolean resizable, boolean closable, boolean maximizable, boolean iconifiable) {
        super(title, resizable, closable, maximizable, iconifiable);
        setOpaque(false);
        init();
    }

    protected void init() {
        MouseAdapter proxy = new MouseAdapter() {

            protected void dispatchEventToParent(MouseEvent e) {
                Container parent = getParent();
                if (parent != null) {
                    e = SwingUtilities.convertMouseEvent(e.getComponent(), e, parent);
                    parent.dispatchEvent(e);
                }
            }

            @Override
            public void mouseMoved(MouseEvent e) {
                dispatchEventToParent(e);
            }

            @Override
            public void mouseDragged(MouseEvent e) {
                dispatchEventToParent(e);
            }

            @Override
            public void mouseWheelMoved(MouseWheelEvent e) {
                dispatchEventToParent(e);
            }

            @Override
            public void mouseExited(MouseEvent e) {
                dispatchEventToParent(e);
            }

            @Override
            public void mouseEntered(MouseEvent e) {
                dispatchEventToParent(e);
            }

            @Override
            public void mouseReleased(MouseEvent e) {
                dispatchEventToParent(e);
            }

            @Override
            public void mousePressed(MouseEvent e) {
                dispatchEventToParent(e);
            }

            @Override
            public void mouseClicked(MouseEvent e) {
                dispatchEventToParent(e);
            }

        };

        addMouseListener(proxy);
        addMouseMotionListener(proxy);
        addMouseWheelListener(proxy);
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setComposite(AlphaComposite.SrcOver.derive(0.25f));
        super.paint(g2d);
        g2d.dispose();
    }

}

public class BackgroundDesktopPane extends JDesktopPane {

    private BufferedImage background;
    private List<Point> points;

    public BackgroundDesktopPane() throws IOException {
        points = new ArrayList<>(25);
        background = ImageIO.read(new File("C:\\Users\\shane\\Dropbox\\Ponies\\800px-Rainbow_Dash_flying_past_1_S2E16.png"));
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                points.add(e.getPoint());
                repaint();
            }

        });
    }

    @Override
    public Dimension getPreferredSize() {
        return background == null ? super.getPreferredSize() : new Dimension(background.getWidth(), background.getHeight());
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g.create();
        if (background != null) {
            int x = (getWidth() - background.getWidth()) / 2;
            int y = (getHeight() - background.getHeight()) / 2;
            g2d.drawImage(background, x, y, this);
        }

        g2d.setColor(Color.RED);
        for (Point p : points) {
            g2d.fillOval(p.x - 5, p.y - 5, 10, 10);
        }
        g2d.dispose();
    }

}