Question

我已经完成了几项检查并完成了如何使单个面板透明化的研究，以便下面的图像显示但JTabbedPane上的面板不成功。我在setOpaque(false)的两个面板上都有setBackground(new Color(0,0,0,20))和JTabbedPane，并且在JTabbedPane本身也是如此。但是，我仍然无法在选项卡式窗格的背面显示图像。我还缺少什么？

tabbePane.java

package tabbedpanetransparencypractice;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.*;

public class tabbedPane extends JTabbedPane{

JPanel tab1panel = new JPanel();
JPanel tab2panel = new JPanel();

public tabbedPane(){
    this.setPreferredSize(new Dimension(400,400));
    this.setBackground(new Color(0,0,0,20));
    this.setOpaque(false);
    tab1panel.setBackground(new Color(0,0,0,20));
    tab2panel.setBackground(new Color(0,0,0,20));
    tab1panel.setOpaque(false);
    tab2panel.setOpaque(false);
    this.addTab("Tab 1", tab1panel);
    this.addTab("Tab 2", tab2panel);
}
}

topPanel.java

package tabbedpanetransparencypractice;
import javax.swing.*;
import java.awt.*;

public class topPanel extends JPanel{
Image myBG = new ImageIcon(getClass().getClassLoader().getResource("Assets/loginBg.jpg")).getImage();
    @Override
    public void paintComponent(Graphics g){
        g.drawImage(myBG,0,0,getWidth(),getHeight(),this);
    }

public topPanel(){
    addTabbedPane();
}

public void addTabbedPane(){
    tabbedPane tabbedpane = new tabbedPane();
    this.add(tabbedpane);
}

}

frame.java

package tabbedpanetransparencypractice;
import java.awt.Dimension;
import javax.swing.*;

public class frame extends JFrame{

topPanel myPanel = new topPanel();

public frame(){
    this.setPreferredSize(new Dimension(600,600));
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setVisible(true);
    this.pack();
    this.setLocationRelativeTo(null);

    addComponents();

}

final void addComponents(){

    this.setContentPane(myPanel);
}
}

main.java

package tabbedpanetransparencypractice;

public class main {

public static void main(String[] args) {
    frame myFrame = new frame();
}
}

这是我得到的输出（我希望tab1和tab2透明以显示下面的bg图像）

我很感激任何帮助。谢谢。

Answer 1

首先，Swing不知道如何处理其背景颜色是基于alpha但是不透明的组件。 Swing只知道如何处理完全不透明和完全透明的组件。

使用基于alpha的颜色会产生奇怪且随机的绘画人工制品。简单的答案是，您不应该将基于alpha的颜色应用于组件的背景（唯一的例外是JFrame - 感谢Sun：P）

主要解决方案是假的。

即，使组件透明（setOpaque(false)）并以降低的alpha级别绘制背景。然后，您可以使用基于alpha的颜色（因为该组件不再依赖于颜色，因为它是透明的），但我倾向于使用AlphaComposite，因为它通常更容易控制和操作。

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class Test {

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

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

                BackgroundPane bp = new BackgroundPane();
                bp.setLayout(new BorderLayout());
                bp.setBorder(new EmptyBorder(20, 20, 20, 20));

                SeeThroughTabbedPane tp = new SeeThroughTabbedPane();
                tp.setAlpha(0.5f);
                tp.addTab("Tab 1", new TestPane("I be see through"));
                tp.addTab("Tab 2", new TestPane("But you can't see me"));

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setContentPane(bp);
                frame.add(tp);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane(String text) {
            setOpaque(false);
            setLayout(new GridBagLayout());
            JLabel label = new JLabel(text);
            label.setForeground(Color.WHITE);
            add(label);
        }

    }

    public class BackgroundPane extends JPanel {

        private BufferedImage bg;

        public BackgroundPane() {
            try {
                bg = ImageIO.read(new File("/Volumes/Disk02/Dropbox/MegaTokyo/megatokyo_omnibus_1_3_cover_by_fredrin-d4oupef 50%.jpg"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return bg == null ? new Dimension(200, 200) : new Dimension(bg.getWidth(), bg.getHeight());
        }

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

    }

    public class SeeThroughTabbedPane extends JTabbedPane {

        private float alpha;

        public SeeThroughTabbedPane() {
            setOpaque(false);
            setAlpha(1f);
        }

        public void setAlpha(float value) {
            if (alpha != value) {
                float old = alpha;
                this.alpha = value;
                firePropertyChange("alpha", old, alpha);
                repaint();
            }
        }

        public float getAlpha() {
            return alpha;
        }

        @Override
        protected void paintComponent(Graphics g) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setColor(getBackground());
            g2d.setComposite(AlphaComposite.SrcOver.derive(getAlpha()));
            g2d.fillRect(0, 0, getWidth(), getHeight());
            g2d.dispose();
            super.paintComponent(g);
        }

    }

}

请记住，您添加到仍然不透明的JTabbedPane的任何内容都将保持不变，而不是在TestPane的构造函数中，我将面板的不透明状态设置为false

您可能还想查看Painting in AWT and Swing和Performing Custom Painting

Answer 2

您可以使用UIManager.put("TabbedPane.contentAreaColor", new Color(255, 255, 0, 100));

screenshot

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

public class TransparentTabbedPaneTest {
  public JComponent makeUI() {
    Color bgc = new Color(110, 110, 0, 100);
    Color fgc = new Color(255, 255, 0, 100);

    UIManager.put("TabbedPane.shadow",                fgc);
    UIManager.put("TabbedPane.darkShadow",            fgc);
    UIManager.put("TabbedPane.light",                 fgc);
    UIManager.put("TabbedPane.highlight",             fgc);
    UIManager.put("TabbedPane.tabAreaBackground",     fgc);
    UIManager.put("TabbedPane.unselectedBackground",  fgc);
    UIManager.put("TabbedPane.background",            bgc);
    UIManager.put("TabbedPane.foreground",            Color.WHITE);
    UIManager.put("TabbedPane.focus",                 fgc);
    UIManager.put("TabbedPane.contentAreaColor",      fgc);
    UIManager.put("TabbedPane.selected",              fgc);
    UIManager.put("TabbedPane.selectHighlight",       fgc);
    UIManager.put("TabbedPane.borderHightlightColor", fgc);

    JTabbedPane tabs = new JTabbedPane();

    JPanel tab1panel = new JPanel();
    tab1panel.setBackground(new Color(0, 220, 220, 50));

    JPanel tab2panel = new JPanel();
    tab2panel.setBackground(new Color(220, 0, 0, 50));

    JPanel tab3panel = new JPanel();
    tab3panel.setBackground(new Color(0, 0, 220, 50));

    JCheckBox cb = new JCheckBox("setOpaque(false)");
    cb.setOpaque(false);
    tab3panel.add(cb);
    tab3panel.add(new JCheckBox("setOpaque(true)"));

    tabs.addTab("Tab 1", tab1panel);
    tabs.addTab("Tab 2", tab2panel);
    tabs.addTab("Tab 3", new AlphaContainer(tab3panel));

    JPanel p = new JPanel(new BorderLayout()) {
      private Image myBG = new ImageIcon(getClass().getResource("test.png")).getImage();
      @Override public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(myBG, 0, 0, getWidth(), getHeight(), this);
      }
    };
    p.add(tabs);
    p.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
    return p;
  }
  public static void main(String... args) {
    EventQueue.invokeLater(() -> {
      JFrame f = new JFrame();
      f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      f.getContentPane().add(new TransparentTabbedPaneTest().makeUI());
      f.setSize(320, 240);
      f.setLocationRelativeTo(null);
      f.setVisible(true);
    });
  }
}

//https://tips4java.wordpress.com/2009/05/31/backgrounds-with-transparency/
class AlphaContainer extends JComponent {
  private JComponent component;
  public AlphaContainer(JComponent component) {
    this.component = component;
    setLayout( new BorderLayout() );
    setOpaque( false );
    component.setOpaque( false );
    add( component );
  }
  /**
   *  Paint the background using the background Color of the
   *  contained component
   */
  @Override
  public void paintComponent(Graphics g) {
    g.setColor( component.getBackground() );
    g.fillRect(0, 0, getWidth(), getHeight());
  }
}

JTabbedPane及其标签透明度无法发挥作用

2 个答案: