Question

这里有一个类似的问题： How to change the size of the font of a JLabel to take the maximum size

但它不能倒退。

因此，如果您使JPanel更大，则字体会增长，但如果您缩小JLabel尺寸并且字体保持不变

Check this Image

如何在调整大小时使Jlabel字体按JPanel大小增长？

Answer 1

使用FontMetrics和TextLayout即可获得此输出（请在代码中阅读评论）

SwingUtilities也可以正确地做到这一点

我建议在两个方向上添加几个像素

将ComponentListener添加到容器中，并在componentResized事件上重新计算FontMetrics

enter image description here

import java.awt.*;
import java.awt.font.TextLayout;
import java.awt.geom.Rectangle2D;
import javax.swing.*;

public class ShowFontMetrics extends JFrame {

    private static final long serialVersionUID = 1L;
    private JLabel lTime;

    public ShowFontMetrics() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel pane = new JPanel();
        pane.setLayout(new FlowLayout());
        lTime = new JLabel("88:88");
        lTime.setFont(new Font("Helvetica", Font.PLAIN, 88));
        FontMetrics fm = lTime.getFontMetrics(lTime.getFont());
        TextLayout layout = new TextLayout(lTime.getText(), lTime.getFont(), fm.getFontRenderContext());
        Rectangle2D bounds = layout.getBounds();
        Dimension d = lTime.getPreferredSize();
        d.height = (int) (bounds.getHeight() + 100);// add huge amount of pixels just for for fun
        d.width = (int) (bounds.getWidth() + 150);// add huge amount of pixels just for for fun
        lTime.setPreferredSize(d);
        lTime.setVerticalAlignment(SwingConstants.CENTER);
        lTime.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        pane.add(lTime);
        setContentPane(pane);
    }

    public static void main(String[] arguments) {
        ShowFontMetrics frame = new ShowFontMetrics();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}

Answer 2

喜欢这个？ http://java-sl.com/tip_adapt_label_font_size.html

更新：

请求的代码

import javax.swing.*;
import java.awt.*;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;

public class ResizeLabelFont extends JLabel {
    public static final int MIN_FONT_SIZE=3;
    public static final int MAX_FONT_SIZE=240;
    Graphics g;

    public ResizeLabelFont(String text) {
        super(text);
        init();
    }

    protected void init() {
        addComponentListener(new ComponentAdapter() {
            public void componentResized(ComponentEvent e) {
                adaptLabelFont(ResizeLabelFont.this);
            }
        });
    }

    protected void adaptLabelFont(JLabel l) {
        if (g==null) {
            return;
        }
        Rectangle r=l.getBounds();
        int fontSize=MIN_FONT_SIZE;
        Font f=l.getFont();

        Rectangle r1=new Rectangle();
        Rectangle r2=new Rectangle();
        while (fontSize<MAX_FONT_SIZE) {
            r1.setSize(getTextSize(l, f.deriveFont(f.getStyle(), fontSize)));
            r2.setSize(getTextSize(l, f.deriveFont(f.getStyle(),fontSize+1)));
            if (r.contains(r1) && ! r.contains(r2)) {
                break;
            }
            fontSize++;
        }

        setFont(f.deriveFont(f.getStyle(),fontSize));
        repaint();
    }

    private Dimension getTextSize(JLabel l, Font f) {
        Dimension size=new Dimension();
        g.setFont(f);
        FontMetrics fm=g.getFontMetrics(f);
        size.width=fm.stringWidth(l.getText());
        size.height=fm.getHeight();

        return size;
    }

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        this.g=g;
    }

    public static void main(String[] args) throws Exception {
        ResizeLabelFont label=new ResizeLabelFont("Some text");
        JFrame frame=new JFrame("Resize label font");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.getContentPane().add(label);

        frame.setSize(300,300);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

}

Answer 3

好的，这是答案。

让我们从这里获取代码：How to change the size of the font of a JLabel to take the maximum size，回答 coobird

int componentWidth = label.getWidth();

我们需要从JFrame组件获取宽度，而不是JLabel，因为代码不会有机会更改JLabel的大小。

这将解决它：

int componentWidth = this.getWidth()-20; // '20' - according width of Jlabel to JFrame

如何在调整大小时更改JLabel字体大小以填充JPanel可用空间？

3 个答案: