我将 JTextArea 放在 JPanel 中。这个 JPanel 在背景上有一张图片，而 JTextArea 是半透明的（半透明红色）以显示背景。我不希望用户能够编辑或选择文本，我希望它充当 JLabel（但具有多行并且易于自动换行和调整屏幕大小）。
我尝试了所有这些选项：
text.setEditable(false);
text.setFocusable(false);
text.setEnabled(false);
text.setHighlighter(null);
但是当用户将鼠标拖到 JTextArea 上时，颜色仍然会发生一些变化。有谁知道发生了什么？
您不能简单地将组件的背景颜色设置为“透明”并期望 Swing 处理它。您需要将组件标记为透明 ( setOpaque(false))，然后 Swing 的重绘管理器才会知道它必须更新其下的组件。
这会导致您遇到如何绘制背景的问题（因为 Swing 只有完全不透明或完全透明的概念）。
为此，您需要提供自己的绘制例程（覆盖paintComponent、填充背景、更新组件）...这基本上就是Rob Camick 的解决方案正在做的事情，它只是为您提供了一个很好的包装组件...
JLabel下面是使用 HTML 和 a 包装的 using 文本的示例JTextArea，两者均已更新为支持“半透明”...
用一个JLabel
用一个JTextArea
现在，使用 Rob 的包装类实现起来会容易得多，但这让您了解出了什么问题以及您需要做些什么来修复它。
public class MultiLineLabel {
public static void main(String[] args) {
new MultiLineLabel();
}
public MultiLineLabel() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new BackgroundPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TransclucentLabel extends JLabel {
public TransclucentLabel(String text) {
super(text);
setVerticalAlignment(TOP);
}
@Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
Insets insets = getInsets();
int x = insets.left;
int y = insets.top;
int width = getWidth() - (insets.left + insets.right);
int height = getHeight() - (insets.top + insets.bottom);
g2d.setColor(new Color(255, 0, 0, 128));
g2d.fillRect(x, y, width, height);
super.paintComponent(g);
}
}
public class TransclucentTextArea extends JTextArea {
public TransclucentTextArea(String text) {
super(text);
setOpaque(false);
setLineWrap(true);
setWrapStyleWord(true);
}
@Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
Insets insets = getInsets();
int x = insets.left;
int y = insets.top;
int width = getWidth() - (insets.left + insets.right);
int height = getHeight() - (insets.top + insets.bottom);
g2d.setColor(new Color(255, 0, 0, 128));
g2d.fillRect(x, y, width, height);
super.paintComponent(g);
}
}
public class BackgroundPane extends JPanel {
private BufferedImage background;
public BackgroundPane() {
setLayout(new BorderLayout());
// addLabel();
addTextArea();
setBorder(new EmptyBorder(24, 24, 24, 24));
try {
background = ImageIO.read(new File("/path/to/your/image"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
protected void addTextArea() {
StringBuilder sb = new StringBuilder(128);
sb.append("I put a JTextArea in a JPanel. This JPanel has a picture on the background, and the JTextArea is translucent (translucid red) to show the background through. I don't want the user to be able to edit or select the text, I want it to act just as a JLabel (but with multiple lines and easy to word wrap and adjust to screen resize).\n\n");
sb.append("I tried all these options:\n\n");
sb.append("text.setEditable(false);\n");
sb.append("text.setFocusable(false);\n");
sb.append("text.setEnabled(false);\n");
sb.append("text.setHighlighter(null);\n\n");
sb.append("but still some change of color happens as the user drags the mouse over the JTextArea. Anyone knows what is going on?\n");
add(new TransclucentTextArea(sb.toString()));
}
protected void addLabel() {
StringBuilder sb = new StringBuilder(128);
sb.append("<html>");
sb.append("<p>I put a JTextArea in a JPanel. This JPanel has a picture on the background, and the JTextArea is translucent (translucid red) to show the background through. I don't want the user to be able to edit or select the text, I want it to act just as a JLabel (but with multiple lines and easy to word wrap and adjust to screen resize).</p><br>");
sb.append("<p>I tried all these options:</p><br>");
sb.append("<p>text.setEditable(false);<br>");
sb.append("text.setFocusable(false);<br>");
sb.append("text.setEnabled(false);<br>");
sb.append("text.setHighlighter(null);</p><br>");
sb.append("<p>but still some change of color happens as the user drags the mouse over the JTextArea. Anyone knows what is going on?</p>");
add(new TransclucentLabel(sb.toString()));
}
@Override
public Dimension getPreferredSize() {
return background == null ? super.getPreferredSize() : new Dimension(background.getWidth(), background.getHeight());
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
int x = (getWidth() - background.getWidth()) / 2;
int y = (getHeight() - background.getHeight()) / 2;
g.drawImage(background, x, y, this);
}
}
}
}