动画透明背景的Linux的JFrame

问题描述：

我想创建一个帧（或JFrame的）一个完全透明的背景，并将它显示一个透明的动画。我设法得到它在Windows 7 X64的工作，但在同一code不上我的Linux（Lubuntu 15.04的x64）上运行。

I want to create a fully transparent background for a Frame (or JFrame) and have it show a transparent animation. I managed to get it working in Windows 7 x64 but the same code does not run on my Linux (Lubuntu x64 15.04).

在code以下显示了我想要实现 - 只需复制和放大器;粘贴。我只是想小矩形在屏幕上移动不留痕迹。

The code below shows what I'm trying to achieve--just copy & paste it. I just want the little rectangle to move across the screen without leaving a trail.

static int  a   = 0;

public static void main(String[] args) {
    JFrame f = new JFrame();
    f.setUndecorated(true);
    f.setBackground(new Color(0, 0, 0, 0));
    f.setVisible(true);
    f.setSize(512, 512);
    f.add(new JPanel() {
        @Override
        public void paintComponent(Graphics gr) {
            Graphics2D g = (Graphics2D)gr;
            g.setBackground(new Color(0, 0, 0, 0));
            g.clearRect(0, 0, 512, 512);
            g.drawRect(a, a++, 2, 2);
        }
    });

    while(true) {
        try {
            Thread.sleep(30);
        } catch(InterruptedException e) {
            e.printStackTrace();
        }
        f.repaint();
    }
}

我想什么来实现（如在Windows中所示）和我所得到的与Lubuntu 15.04：

What I want to achieve (as shown in Windows) and what I get with Lubuntu 15.04:

＆NBSP;＆NBSP;＆NBSP;＆NBSP;＆NBSP;＆NBSP;＆NBSP;＆NBSP;

我只是想看看小方举动，就像在Windows 7上显示什么的 - 我不希望看到一个线索

I just want to see the little square move just like what's shown on Windows 7--I don't want to see a trail.

请不要给我甲骨文的透明度和窗口文档的链接 - 从来就超过了所有三次

Please don't give me the link of Oracle's transparency and window documentation--I've gone over it all thrice.

我已经试过：

的Graphics2D的'那么copyArea（）透明空间。（这曾经工作，据我所知，但不再做）

玻璃面板

的AlphaComposite

setPaint（）

请请你只测试出你的想法/ code第一。很多的这应该工作的东西，我已经尝试过，不似乎...所有帮助是极大的AP preciated。

Please please just test out your thoughts/code first. A lot of the "this should work" stuff I have already tried and does not seem to... All help is greatly appreciated.

答

有关参考，这里有一个最小的完整的例子，适合跨平台测试。需要注意的是

For reference, here's a minimal complete example, suitable for cross-platform testing. Note that

在某些平台上，例如Ubuntu的，一个的完全的透明背景不被视为不透明;一个小的，非零的字母的值是一个典型的解决方法。

On some platforms, e.g. Ubuntu, a completely transparent background is not seen as opaque; a small, non-zero alpha value is a typical work-around.

Swing GUI的对象应当建立和操纵的只有的上的事件调度线程。

Swing GUI objects should be constructed and manipulated only on the event dispatch thread.

使用 java.swing。定时器 ，运行事件调度线程上，踱步动画。

Use java.swing.Timer, which runs on the event dispatch thread, to pace the animation.

不要使用集preferredSize（）当你真正的意思是覆盖的 的get preferredSize（） 。

Don't use setPreferredSize() when you really mean to override getPreferredSize().

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;

/**
 * @see http://stackoverflow.com/a/31328464/230513
 */
public class TransparentAnimation {

    private static final Color tranparentBlack = new Color(0, 0, 0, 1);

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setUndecorated(true);
        f.setBackground(tranparentBlack);
        f.add(new JPanel() {
            int x, y;
            Timer t = new Timer(10, (ActionEvent e) -> {
                x = (x + 1) % getWidth();
                y = (y + 1) % getHeight();
                repaint();
            });

            {
                setBackground(tranparentBlack);
                t.start();
            }

            @Override
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.drawRect(0, 0, getWidth() - 1, getHeight() - 1);
                g.fillOval(x, y, 16, 16);
            }

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(320, 240);
            }
        });
        f.add(new JLabel(System.getProperty("os.name") + "; v"
            + System.getProperty("os.version")), BorderLayout.SOUTH);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new TransparentAnimation()::display);
    }
}

动画透明背景的Linux的JFrame

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