如何使JSlider背景透明?或如何在JLayeredPane中正确叠加JComponent? [英] How do I make a JSlider background transparent? or How do I properly overlay JComponents in JLayeredPane?

问题描述

我正在尝试在JProgressBar顶部叠加JSlider.我正在使用JLayeredPane来容纳这两个组件.我将JProgressBar添加到JLayeredPane，然后添加JSlider.到目前为止，我已经尝试通过将opaque设置为false并覆盖paintComponent方法来使JSlider透明.我最后要说的是，当背景保持不透明时，滑块手柄是唯一变得透明的部分.我可能没有正确使用JLayeredPane，但我使用JLabels进行的测试似乎有效.如何使JSlider的背景透明?

I am trying to overlay a JSlider on top of a JProgressBar. I am using a JLayeredPane to hold the two components. I am adding the JProgressBar to the JLayeredPane and then adding the JSlider. So far, I have attempted to make the JSlider transparent by setting opaque to false and overriding the paintComponent method. What I end up with is that the slider handle is the only part that becomes transparent while the background stays opaque. It is possible that I am not using the JLayeredPane correctly, but my tests with JLabels seemed to work. How do I get the background of the JSlider to be transparent?

JSlider slider = new JSlider()
{

    @Override
    public void paintComponent(java.awt.Graphics g)
    {
        java.awt.Graphics2D g2 = (java.awt.Graphics2D) g;
        g2.setComposite(AlphaComposite.getInstance(
                AlphaComposite.SRC_OVER, (float) 0.5));

        super.paintComponent(g2);
    }

};

谢谢大家的帮助.通过您的示例，我发现我的问题与我使用的JLayeredPane有关.我认识到可以使JSlider背景透明，但是，我仍然无法获得下面各层上的组件来显示.这是我的示例:

Thank you all for your help. Through your examples, I have discovered that my issue is with the JLayeredPane that I am using. I recognize that the JSlider background can be made transparent, however, I still cannot get the components on layers beneath to show through. This is my example:

public class SliderTest extends JFrame
{

private JPanel contentPane;

/**
 * Launch the application.
 */
public static void main(String[] args)
{
    EventQueue.invokeLater(new Runnable()
    {
        public void run()
        {
            try
            {
                SliderTest frame = new SliderTest();
                frame.setVisible(true);
            } catch (Exception e)
            {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public SliderTest()
{
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setLayout(new BorderLayout(0, 0));
    setContentPane(contentPane);

    JPanel panel = new JPanel();
    contentPane.add(panel, BorderLayout.CENTER);
    panel.setLayout(new BorderLayout(0, 0));

    JLayeredPane layeredPane = new JLayeredPane();

    panel.add(layeredPane, BorderLayout.CENTER);
    layeredPane.setLayout(new BorderLayout(0, 0));

    JProgressBar progressBar = new JProgressBar();
    progressBar.setValue(50);
    layeredPane.add(progressBar);
    layeredPane.setLayer(progressBar, 0);

    JSlider slider = new JSlider()
    {
        @Override
        protected void paintComponent(Graphics g)
        {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setColor(getBackground());
            g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
            g2d.fillRect(0, 0, getWidth(), getHeight());
            g2d.dispose();

            super.paintComponent(g);
        }

    };
    layeredPane.setLayer(slider, 1);
    slider.setOpaque(false);

    // layeredPane.setLayer(slider, 1);
    layeredPane.add(slider, BorderLayout.CENTER);

}

}

推荐答案

这将取决于您要实现的目标.默认情况下，JSlider是透明的.

This will depend upon what it is you want to achieve. By default JSlider is transparent.

这里重要的是不透明属性必须为false，否则重新绘制管理器将不会在组件后面绘制...

What's important here is that the opaque property MUST be false, otherwise the repaint manager will not paint behind the components...

• 顶部滑块，透明背景(蓝色)，不透明控件
• 中间滑块，透明背景(绿色)，透明控件

• 底部滑块，正常JSlider

公共类TestSlider {

public class TestSlider {

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

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

            JFrame frame = new JFrame("Test");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setLayout(new BorderLayout());
            frame.add(new TestPane());
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
        }

    });
}

public class TestPane extends JPanel {

    public TestPane() {
        setBackground(Color.RED);

        setLayout(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        gbc.fill = GridBagConstraints.HORIZONTAL;

        add(new TransparentBackgroundSlider(), gbc);
        add(new TransparentSlider(), gbc);
        add(new JSlider(), gbc);

    }

}

public class TransparentBackgroundSlider extends JSlider {

    public TransparentBackgroundSlider() {
        // Important, we taking over the filling of the
        // component...
        setOpaque(false);
        setBackground(Color.BLUE);
    }

    @Override
    protected void paintComponent(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setColor(getBackground());
        g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
        g2d.fillRect(0, 0, getWidth(), getHeight());
        g2d.dispose();

        super.paintComponent(g);
    }

}

public class TransparentSlider extends JSlider {

    public TransparentSlider() {
        // Important, we taking over the filling of the
        // component...
        setOpaque(false);
        setBackground(Color.GREEN);
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
        super.paint(g2d);
        g2d.dispose();
    }

    @Override
    protected void paintComponent(Graphics g) {
        // We need this because we've taken over the painting of the component
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setColor(getBackground());
        g2d.fillRect(0, 0, getWidth(), getHeight());
        g2d.dispose();

        super.paintComponent(g);
    }

}

}

更新图层示例

public class TestSlider {

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

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

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }

        });
    }

    public class TestPane extends JLayeredPane {

        private JProgressBar pb;
        private JSlider slider;

        public TestPane() {

            pb = new JProgressBar();
            slider = new JSlider();

            add(pb, new Integer(0));
            add(slider, new Integer(1));

        }

        @Override
        public Dimension getPreferredSize() {
            Dimension size = pb.getPreferredSize();
            size.height *= 4;
            size.width = Math.max(size.width, slider.getPreferredSize().width);
            return size;
        }

        @Override
        public void doLayout() {
            super.doLayout();

            int width = getWidth();
            int height = getHeight();

            Dimension size = pb.getPreferredSize();

            int x = 10;
            int y = (getHeight() - size.height) / 2;

            pb.setLocation(x, y);
            size.width = getWidth() - 21;
            pb.setSize(size);

            size = slider.getPreferredSize();
            x = (getWidth() - size.width) / 2;
            y = (getHeight() - size.height) / 2;
            slider.setBounds(x, y, size.width, size.height);

        }

    }

}

这篇关于如何使JSlider背景透明?或如何在JLayeredPane中正确叠加JComponent?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！