Java 使JLabel背景在具有背景的帧中透明
我的JFrame上有一个JLabel和一个带有图片背景的JFrame。问题是虽然我的JLabel是不透明的,但它仍然有一个令人讨厌的灰色背景。Java 使JLabel背景在具有背景的帧中透明,java,swing,graphics,transparency,jlabel,Java,Swing,Graphics,Transparency,Jlabel,我的JFrame上有一个JLabel和一个带有图片背景的JFrame。问题是虽然我的JLabel是不透明的,但它仍然有一个令人讨厌的灰色背景。 这是我的密码: import java.awt.Graphics; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import java.awt.Image; import javax.swing.JFrame; import javax.swing.JLabel;
这是我的密码:
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
public class MainFrame extends JFrame {
private JTextField username;
private JPasswordField password;
private JLabel passwordLbl;
private JLabel usernameLbl;
private GridBagConstraints gc;
public MainFrame() {
username = new JTextField(10);
password = new JPasswordField(10);
passwordLbl = new JLabel("Password: ");
usernameLbl = new JLabel("Username: ");
usernameLbl.setOpaque(true);
passwordLbl.setOpaque(true);
setLayout(new GridBagLayout());
gc = new GridBagConstraints();
gc.weightx = 1;
gc.weighty = 1;
gc.gridx = 1;
gc.gridy = 0;
add(username, gc);
gc.gridx = 1;
gc.gridy = 1;
add(password, gc);
gc.gridx = 0;
gc.gridy = 0;
add(usernameLbl, gc);
gc.gridx = 0;
gc.gridy = 1;
add(passwordLbl, gc);
setSize(400, 600);
setLocation(400, 50);
setUndecorated(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
@Override
public void paint(Graphics arg0) {
Image img = getToolkit().getImage("pics/blue_and_red.jpg");
arg0.drawImage(img, 0, 0, getWidth(), getHeight(), this);
username.repaint();
password.repaint();
usernameLbl.setOpaque(true);
usernameLbl.repaint();
passwordLbl.repaint();
}
}
提前感谢。您的绘画方法完全错误是您出现问题的原因。不要在画图中画标签,但要在画图中调用
super.paint(g)
更好的是,不要使用JFrame的paint方法,而是使用JPanel的paintComponent方法并在那里调用super的方法
i、 e
public class MainPanel extends JPanel {
private JTextField username;
private JPasswordField password;
private JLabel passwordLbl;
private JLabel usernameLbl;
private GridBagConstraints gc;
private Image img;
public MainPanel() {
img = getToolkit().getImage("pics/blue_and_red.jpg");
username = new JTextField(10);
password = new JPasswordField(10);
passwordLbl = new JLabel("Password: ");
usernameLbl = new JLabel("Username: ");
// usernameLbl.setOpaque(true);
// passwordLbl.setOpaque(true);
setLayout(new GridBagLayout());
gc = new GridBagConstraints();
gc.weightx = 1;
gc.weighty = 1;
gc.gridx = 1;
gc.gridy = 0;
add(username, gc);
gc.gridx = 1;
gc.gridy = 1;
add(password, gc);
gc.gridx = 0;
gc.gridy = 0;
add(usernameLbl, gc);
gc.gridx = 0;
gc.gridy = 1;
add(passwordLbl, gc);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, getWidth(), getHeight(), this);
}
// username.repaint();
// password.repaint();
// usernameLbl.setOpaque(true);
// usernameLbl.repaint();
// passwordLbl.repaint();
}
private static void createAndShowGui() {
// create JFrame
JFrame frame = new JFrame("BUI");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// add our MainPanel to the JFrame
frame.getContentPane().add(new MainPanel());
frame.pack(); // pack it
frame.setLocationByPlatform(true);
frame.setVisible(true); // show it
}
public static void main(String[] args) {
// this is for starting our Swing app on the event thread
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
最重要的是,请阅读标准的Swing教程,因为这里已经对其进行了很好的解释。嗯。。。。让它不不透明。认真地或者更好的是,甚至不要将不透明设置为false,因为非不透明是默认值。默认情况下,它不起作用,它是非不透明的。因为你的绘制方法都有问题。不要在绘画时加载图片,而是在构建课程时加载一次。并且不要从一个内部调用repaintpainting@HovercraftFullOfEels令人沮丧的是,人们没有准备好倾听智者的建议;)不幸的是,它是一个JFrame,没有paintComponent。我试过使用super.paint(g)它不起作用。@Iman:正如我所说的,不要在JFrame中画画,这是一件非常危险的事情。绘制在JFrame中显示的JPanel。这在Swing绘画教程中都有解释。@Iman:它的工作原理是向JFrame添加一个JPanel,并在paintComponent的末尾使用一个repaint()重写JPanel的paintComponent方法@气垫船:非常感谢;)