在用paintComponent绘制的图形上显示JLabel

Question

I've a class extending JLabel . This JLabel has a particolar shape and I draw that in the method paintComponent . I want to show a text in the center of the jLabel but this text is not shown. Could anyone help me.

My simple HLabel class in the following:

private class Scudetto extends JLabel {

    private static final long serialVersionUID = 1L;

    public Scudetto(String line_point)
    {
        super(line_point, SwingUtilities.CENTER);
        this.setOpaque(true);
        this.setBackground(Color.BLACK);
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Dimension d = this.getSize();

        int[] x = { 0, d.width,      d.width, d.width / 2,             0 };
        int[] y = { 0,       0, d.height / 2,     d.height, d.height / 2 };

        g.setColor(Color.WHITE);
        g.fillPolygon(x, y, 5);

        g.setColor(Color.BLACK);

    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(10, 20);
    }

}

Answer 1

I want to show a text in the center of the jLabel but this text is not shown.

The super.paintComponent() will paint the text, but then your custom painting will paint the polygon over top of the text.

Don't override the JLabel. Instead you can create a PolygonIcon . Then you add the Icon and text to the JLabel.

You can have the text centered on the label by using:

JLabel label = new JLabel("your text");
label.setIcon( polygonIcon );
label.setHorizontalTextPosition(JLabel.CENTER);
label.setVerticalTextPosition(JLabel.CENTER);

Here is a simple example of creating a rectangular Icon:

import java.awt.*;
import javax.swing.*;

public class ColorIcon implements Icon
{
    private Color color;
    private int width;
    private int height;

    public ColorIcon(Color color, int width, int height)
    {
        this.color = color;
        this.width = width;
        this.height = height;
    }

    public int getIconWidth()
    {
        return width;
    }

    public int getIconHeight()
    {
        return height;
    }

    public void paintIcon(Component c, Graphics g, int x, int y)
    {
        g.setColor(color);
        g.fillRect(x, y, width, height);
    }

    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

    public static void createAndShowGUI()
    {
        JPanel panel = new JPanel( new GridLayout(2, 2) );

        for (int i = 0; i < 4; i++)
        {
            Icon icon = new ColorIcon(Color.RED, 50, 50);
            JLabel label = new JLabel( icon );
            label.setText("" + i);
            label.setHorizontalTextPosition(JLabel.CENTER);
            label.setVerticalTextPosition(JLabel.CENTER);
            panel.add(label);
        }

        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(panel);
        f.setSize(200, 200);
        f.setLocationRelativeTo( null );
        f.setVisible(true);
    }
}

I'll let you modify the code for a polygon.

You can also check out Playing With Shapes for some fun ways to create an Icon of different shapes.