Layout Manager for background images and text

问题

I'm trying to think of the best layout manager to achieve the picture below. I know absolute positioning is what I am used to, but I can't get the background image using this. GridBagLayout is excellent, but horrifically hard when ever I try I get a separate image for each grid.

Does anyone know an easy way out of this, or easy code to achieve the following?

回答1:

There are a number of ways you can achieve this.

The simplest might be to just use what's already available

...

If you don't need the background to be scaled at run-time (ie you can get away with a non-resizable window), simply using a JLabel as the primary container could make your life significantly easier.

public class LabelBackground {

    public static void main(String[] args) {
        new LabelBackground();
    }

    public LabelBackground() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new LoginPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class LoginPane extends JLabel {

        public LoginPane() {
            try {
                setIcon(new ImageIcon(ImageIO.read(getClass().getResource("/background.jpg"))));
            } catch (IOException ex) {
                ex.printStackTrace();
            }
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.anchor = GridBagConstraints.EAST;
            gbc.insets = new Insets(2, 2, 2, 2);
            gbc.gridx = 0;
            gbc.gridy = 0;

            JLabel nameLabel = new JLabel("Name: ");
            nameLabel.setForeground(Color.WHITE);
            JLabel passwordLabel = new JLabel("Password: ");
            passwordLabel.setForeground(Color.WHITE);

            add(nameLabel, gbc);
            gbc.gridy++;
            add(passwordLabel, gbc);

            gbc.anchor = GridBagConstraints.WEST;
            gbc.gridx++;
            gbc.gridy = 0;
            add(new JTextField(20), gbc);
            gbc.gridy++;
            add(new JTextField(20), gbc);

            gbc.gridy++;
            gbc.insets = new Insets(10, 2, 2, 2);
            gbc.anchor = GridBagConstraints.EAST;
            add(new JButton("Submit"), gbc);

        }

    }

}

Updated with example of left alignment

At the end of the constructor, add...

JPanel filler = new JPanel();
filler.setOpaque(false);
gbc.gridx++;
gbc.weightx = 1;
add(filler, gbc);

You might like to take a look at How to use GridBagLayout for more details

回答2:

There are several ways to do it. These are what I can think of at the moment:

Create a subclass of JComponent.
Override the paintComponent(Graphics g) method to paint the image that you want to display.
Set the content pane of the JFrame to be this subclass.

Some sample code:

class ImagePanel extends JComponent {
    private Image image;
    public ImagePanel(Image image) {
        this.image = image;
    }
    @Override
    protected void paintComponent(Graphics g) {
        g.drawImage(image, 0, 0, null);
    }
}

// elsewhere
BufferedImage myImage = ImageIO.read(...);
JFrame myJFrame = new JFrame("Image pane");
myJFrame.setContentPane(new ImagePanel(myImage));

Note that this code does not handle re-sizing the image to fit the JFrame, if that's what you wanted.

来源：https://stackoverflow.com/questions/14926425/layout-manager-for-background-images-and-text

标签

java

swing

layout

gridbaglayout

imageicon