我有JFrame
JLabel label1
,但我不能让它显示图像。每当另一个类调用showScreenShot()
时,如何在标签中显示更新的缓冲图像?
我正在使用Eclipse WindowBuilder。
以下是代码:
public class TeacherDashBoard extends JFrame {
private JPanel contentPane;
private BufferedImage img;
private static TeacherDashBoard frame;
private static JLabel label1;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
frame = new TeacherDashBoard();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public void showScreenShot(byte[] bytes) throws IOException {
img = ImageIO.read(new ByteArrayInputStream(bytes));
label1.getGraphics().drawImage(img, 0, 0, label1.getWidth(), label1.getHeight(), null);
}
public TeacherDashBoard() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 424);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
label1 = new JLabel();
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
layout.setHorizontalGroup(layout.createParallelGroup(Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(29)
.addComponent(label1, GroupLayout.PREFERRED_SIZE, 210, GroupLayout.PREFERRED_SIZE)
.addContainerGap(591, Short.MAX_VALUE))
);
layout.setVerticalGroup(layout.createParallelGroup(Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(96)
.addComponent(label1, GroupLayout.PREFERRED_SIZE, 104, GroupLayout.PREFERRED_SIZE)
.addContainerGap(333, Short.MAX_VALUE))
);
getContentPane().setLayout(layout);
pack();
}
}
答案 0 :(得分:2)
这至少在两个不同的层面上是错误的:
label1.getGraphics().drawImage(img, 0, 0, label1.getWidth(), label1.getHeight(), null);
getGraphics()
。对组件的更改将是短暂的,因为Swing组件需要在告知时自行绘制。null
作为图像观察者。 AWT / Swing中的每个组件都实现ImageObserver
。改为使用:
label1.setIcon(new ImageIcon(img));