要创建透明窗口，您需要将框架背景色的 Alpha设置为0。这可能是我一段 时间以来看到的最不直观的调用，就好像您对任何其他Swing组件执行此操作一样，您将完全 搞砸绘制过程。
您不想更改窗口的不透明度，因为它会影响 整个窗口，并且其内容均等。
例如…
JWindow frame = new JWindow();
frame.setBackground(new Color(0, 0, 0, 0));
frame.setBackground(new Color(0, 0, 0, 0)); 您不必使用JWindow，但这意味着我不需要 自己修饰它…
您还需要确保添加到窗口的任何内容都是 透明的（opaque = false），以便它不会“隐藏”其下面的 内容……
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.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;
public class LeafWindow {
public static void main(String[] args) {
new LeafWindow();
}
public LeafWindow() {
EventQueue.invokelater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | illegalaccessexception | UnsupportedLookAndFeelException ex) {
}
JWindow frame = new JWindow();
frame.setBackground(new Color(0, 0, 0, 0));
frame.setContentPane(new LeafPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setAlwaysOnTop(true);
}
});
}
public class LeafPane extends JPanel {
private BufferedImage leaf;
public LeafPane() {
setBorder(new CompoundBorder(
new LineBorder(Color.RED),
new EmptyBorder(0, 0, 250, 0)));
try {
leaf = ImageIO.read(getClass().getResource("/Leaf.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
setOpaque(false);
setLayout(new GridBagLayout());
JButton button = new JButton("Close");
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
add(button);
}
@Override
public Dimension getPreferredSize() {
return leaf == null ? new Dimension(200, 200) : new Dimension(leaf.getWidth(), leaf.getHeight());
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (leaf != null) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.drawImage(leaf, 0, 0, this);
g2d.dispose();
}
}
}
}
本示例故意为内容添加线边框，因为您可以看到原始的窗口边界。它还使用aEmptyBorder强制将其 JButton拖到图形上，但这只是一个示例……
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