我使用以下代码片段来创建聊天日志。
chatlog = new JEditorPane("text/html", "<html>") {
private static final long serialVersionUID = 1L;
protected void paintComponent(Graphics g) {
// set background green - but can draw image here too
g.setColor(new Color(0,0,0,0));
g.fillRect(0, 0, getWidth(), getHeight());
// uncomment the following to draw an image
Image img;
try {
img = ImageIO.read(new File("images/chatlog.png"));
g.drawImage(img, 0, 0, this);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
super.paintComponent(g);
}
};
chatlog.setFont(new Font("Segoe UI", Font.PLAIN, 14));
chatlog.setEditable(false);
chatlog.setOpaque(false);
chatScroll = new JScrollPane(chatlog);
chatScroll.setBounds(4, 454, 620, 100);
chatScroll.setOpaque(false);
chatScroll.setBackground(new Color(0,0,0,0));
chatScroll.setBorder(BorderFactory.createEmptyBorder());
chatScroll.setVisible(false);
如您所见，我在 JEditorPane 中使用背景图像。但是，如果我在聊天日志中写入大量内容，背景图像会随文本一起向上移动。
你能帮我吗？
最佳答案
在标准 HTML 中，我们将使用 background-attachment:scroll; CSS 属性来强制 BG 在用户滚动页面时向下滚动。黄点被放置在样式中作为背景，以显示 Swing 如何不实现该属性。
另一方面，宽短的黑色图像是由滚动 Pane 本身绘制的，因此出现在我们想要绘制它的任何地方。
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class BackgroundImageInHTML {
// the GUI as seen by the user (without frame)
private JPanel gui;
private final static String HTML = "<html>"
+ "<head>"
+ "<style type=text/css>"
+ "body {"
+ " background-image: /image/IHARa.png;"
+ " background-repeat:no-repeat;"
+ " background-position:left top;"
+ " background-attachment: scroll;"
+ " color: #BBBBBB;"
+ "}"
+ "</style>"
+ "</head>"
+ "<body>"
+ "<h1>Heading 1</h1>";
private final String PARAGRAPH = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean eu nulla urna. Donec sit amet risus nisl, a porta enim. Quisque luctus, ligula eu scelerisque gravida, tellus quam vestibulum urna, ut aliquet sapien purus sed erat. Pellentesque consequat vehicula magna, eu aliquam magna interdum porttitor. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Sed sollicitudin sapien non leo tempus lobortis. Morbi semper auctor ipsum, a semper quam elementum a. Aliquam eget sem metus.";
BackgroundImageInHTML() {
initializGui();
}
public void initializGui() {
gui = new JPanel(new BorderLayout());
gui.setBorder(new EmptyBorder(5, 5, 5, 5));
// TODO - not ideal
gui.setPreferredSize(new Dimension(400, 100));
StringBuilder sb = new StringBuilder();
sb.append(HTML);
for (int ii = 0; ii < 10; ii++) {
sb.append("<h2>Header 2</h2>");
sb.append(PARAGRAPH);
}
JEditorPane jep = new JEditorPane();
jep.setOpaque(false);
jep.setContentType("text/html");
jep.setText(sb.toString());
JScrollPane jsp = new JScrollPane(jep) {
BufferedImage bg = new BufferedImage(350,50,BufferedImage.TYPE_INT_RGB);
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(bg, 0, 0, this);
}
};
jsp.getViewport().setOpaque(false);
gui.add(jsp);
}
public JComponent getGui() {
return gui;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
@Override
public void run() {
BackgroundImageInHTML bih = new BackgroundImageInHTML();
JFrame f = new JFrame("Demo");
f.add(bih.getGui());
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See http://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.pack();
// should be done last, to avoid flickering, moving,
// resizing artifacts.
f.setVisible(true);
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency
SwingUtilities.invokeLater(r);
}
}
关于java - JScrollPane 中的 JEditorPane 具有修复背景图像，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21073826/