要制作透明窗口,您需要将框架背景颜色 alpha 设置为0
。这可能是我一段时间以来见过的最违反直觉的调用,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,因为它对整个窗口及其内容同样有效。
例如...
JWindow frame = new JWindow();
frame.setBackground(new Color(0, 0, 0, 0));
你不必使用JWindow
,但这意味着我不需要自己取消装饰......
您还需要确保添加到窗口的任何内容都是透明的(opaque = false),这样它就不会“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();
}
}
}
}
此示例特意向内容添加了线条边框,因为您可以看到原始窗口边界是什么。它还使用一个EmptyBorder
来强制JButton
到图形上,但这只是一个例子......