如何消除大尺寸的Java Swing标签中的间隙

Question

在我的应用程序中，我有一个字体大小超过200的标签。此标签包含较大的上下（不规则）间隙。如何将其删除？

这是我的代码：

package Core;

import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

public class LabelDemo extends JPanel {
    public LabelDemo() {
        super(new GridBagLayout()); 
        JLabel label2;
        GridBagConstraints c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 0;
        // Create the other labels.
        label2 = new JLabel("Text-Only Label");
        label2.setBorder(BorderFactory.createTitledBorder("aaaaaaaa"));
        label2.setFont(new Font("Verdana", Font.PLAIN, (int) 220));
        // label2.setBorder(new EmptyBorder(-50, 0, 0, 0));

        // Add the labels.
        add(label2, c);
    }

    /**
     * Create the GUI and show it. For thread safety, this method should be invoked from the event dispatch thread.
     */
    private static void createAndShowGUI() {
        // Create and set up the window.
        JFrame frame = new JFrame("LabelDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Add content to the window.
        frame.add(new LabelDemo());

        // Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        // Schedule a job for the event dispatch thread:
        // creating and showing this application's GUI.
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                // Turn off metal's use of bold fonts
                UIManager.put("swing.boldMetal", Boolean.FALSE);

                createAndShowGUI();
            }
        });
    }
}

有什么更好的方法可以消除这种差距吗？

Answer 1

JDigit may give you some
ideas:

• It override’s paintComponent() to down-sample a high-resolution BufferedImage and control the geometry.

• It uses setBorderPainted(false) to set the borderPainted property.

• It uses a FocusHandler for custom highlighting.

Addendum: As noted here, the
underlying problem is the font’s leading , defined in
FontMetrics
as being included in the font’s height. As suggested in a comment by
@Guillaume Polet, you can render the text wherever you want in your own
JComponent. TextLayout, discussed here can be used to calculate
the bounds, as shown below.

Pros:

• Absolute control over placement.

• Geometry of TexteLayout bounds based on FontMetrics.

Cons:

• No Icon support.

• No HTML support.

Note that the JComponent authors “recommend that you put the component in a
JPanel and set the border on the JPanel.”

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 * @see https://stackoverflow.com/a/16014525/230513
 */
public class UnleadedTest {

    private static class Unleaded extends JComponent {

        private Font font = new Font("Verdana", Font.PLAIN, 144);
        private FontRenderContext frc = new FontRenderContext(null, true, true);
        private String text;
        private TextLayout layout;
        private Rectangle r;

        public Unleaded(String text) {
            this.text = text;
            calcBounds();
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(r.width, r.height);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g;
            calcBounds();
            layout.draw(g2d, -r.x, -r.y);
        }

        private void calcBounds() {
            layout = new TextLayout(text, font, frc);
            r = layout.getPixelBounds(null, 0, 0);
        }
    }

    private void display() {
        JFrame f = new JFrame("Unleaded");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Unleaded label = new Unleaded("Unleaded");

        JPanel panel = new JPanel();
        panel.setBorder(BorderFactory.createTitledBorder("Title"));
        panel.add(label);
        f.add(panel);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new UnleadedTest().display();
            }
        });
    }
}