java中JLabel圆角的最简单代码[重复]

Question

我有很多JLabel，希望它们的拐角处平滑。我怎样才能做到这一点？我已经在 SO 上搜索过，但没有找到任何答案。

有人可以帮我提供一个简单而准确的代码来为JLabel's 制作圆角吗？

其他问题是询问一些额外的细节，如边框等，但我只想要精确和最简单的代码来为JLabel's 制作圆角。

Answer 1

说真的，最简单的解决方案是在 JLabel 周围画一个 RoundRectangle2D...

现在，您可以在标签的 paintComponent 或 paintBorder 方法中执行此操作，但是当您可以制作自己的边框以可重复使用的方式完成工作时，您为什么还要打扰，例如...

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.geom.RoundRectangle2D;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.AbstractBorder;

public class TestRoundedBorder {

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

    public TestRoundedBorder() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

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

    public class TestPane extends JPanel {

        public TestPane() {
            setBackground(Color.RED);
            setLayout(new GridBagLayout());
            JLabel label = new JLabel("Test");
            label.setBorder(new RoundedBorder(Color.BLACK, 20));
            add(label);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }

    public class RoundedBorder extends AbstractBorder {

        private final Color color;
        private final int gap;

        public RoundedBorder(Color c, int g) {
            color = c;
            gap = g;
        }

        @Override
        public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setColor(color);
            g2d.draw(new RoundRectangle2D.Double(x, y, width - 1, height - 1, gap, gap));
            g2d.dispose();
        }

        @Override
        public Insets getBorderInsets(Component c) {
            return (getBorderInsets(c, new Insets(gap, gap, gap, gap)));
        }

        @Override
        public Insets getBorderInsets(Component c, Insets insets) {
            insets.left = insets.top = insets.right = insets.bottom = gap / 2;
            return insets;
        }

        @Override
        public boolean isBorderOpaque() {
            return false;
        }
    }

}

现在，如果您想要“平滑”边缘，您将不得不将 RenderingHints 提供给 Graphics 上下文，例如...

public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
    Graphics2D g2d = (Graphics2D) g.create();
    g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
    g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
    g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
    g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
    g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
    g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
    g2d.setColor(color);
    g2d.draw(new RoundRectangle2D.Double(x + 1, y + 1, width - 2, height - 2, gap, gap));
    g2d.dispose();
}

Answer 2

您不能在实际的JLabel 区域上进行圆角；它们总是矩形的。但是，一个简单的替代方法是将JLabel 的ImageIcon 设置为具有圆边且不使用边框的图像。设置ImageIcon：

yourLabel.setIcon(new ImageIcon(getClass().getResource("/path/to/your/image.png"));
// Note: Relative path, starts from root of project

您的图像应该具有JLabel 的尺寸。 请注意，如果找不到图像，这将抛出NullPointerException。确保你走对了路！

创建一个ImageIcon，将其大小调整为JLabel：

ImageIcon ico = new ImageIcon("/path/to/your/image.png");
Image img = ico.getImage();
BufferedImage bi = new BufferedImage(img.getWidth(null), img.getHeight(null), BufferedImage.TYPE_INT_ARGB);
Graphics g = bi.createGraphics();
g.drawImage(img, 0, 0, yourLabel.getWidth(), yourLabel.getHeight(), null);
IconImage newIco = new IconImage(bi);
yourLabel.setIcon(newIco);

编辑：

这是使用Graphics2D 制作圆角边框的最佳方法。 首先，创建一个名为 RoundedBorder 的新类。将此代码粘贴到其中：

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.geom.Line2D;
import javax.swing.border.AbstractBorder;

public class RoundedBorder extends AbstractBorder {

public RoundedBorder(Color c, int g) {
    color = c;
    gap = g;
}

@Override
public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
    super.paintBorder(c, g, x, y, width, height);
    Graphics2D g2d;
    if (g instanceof Graphics2D) {
        g2d = (Graphics2D) g;
        g2d.setColor(color);
        System.out.println(x + y);
        g2d.draw(new Line2D.Double((double)x, (double)y + 10, (double)x + 3, (double)y + 3));
        g2d.draw(new Line2D.Double((double)x + 3, (double)y + 3, (double)x + 10, (double)y));
        g2d.draw(new Line2D.Double((double)x + 10, (double)y, (double)x + 30, (double)y));
        g2d.draw(new Line2D.Double((double)x + 30, (double)y, (double)x + 33, (double)y + 2));
        g2d.draw(new Line2D.Double((double)x + 33, (double)y + 2, (double)x + 36, (double)y + 8));
        g2d.draw(new Line2D.Double((double)x + 36, (double)y + 8, (double)x + 36, (double)y + 28));
        g2d.draw(new Line2D.Double((double)x + 36, (double)y + 28, (double)x + 34, (double)y + 31));
        g2d.draw(new Line2D.Double((double)x + 34, (double)y + 31, (double)x + 32, (double)y + 33));
        g2d.draw(new Line2D.Double((double)x + 32, (double)y + 33, (double)x + 6, (double)y + 33));
        g2d.draw(new Line2D.Double((double)x + 6, (double)y + 33, (double)x + 3, (double)y + 31));
        g2d.draw(new Line2D.Double((double)x + 3, (double)y + 31, (double)x, (double)y + 27));
        g2d.draw(new Line2D.Double((double)x, (double)y + 27, (double)x, (double)y + 10));
    }
}

@Override
public Insets getBorderInsets(Component c) {
    return (getBorderInsets(c, new Insets(gap, gap, gap, gap)));
}

@Override
public Insets getBorderInsets(Component c, Insets insets) {
    insets.left = insets.top = insets.right = insets.bottom = gap;
    return insets;
}

@Override
public boolean isBorderOpaque() {
    return true;
}

// Variable declarations
private final Color color;
private final int gap;
}

然后，在您的 JFrame 类中，将此设置为 JLabel 的边框，请执行以下操作：

yourLabel.setBorder(new RoundedBorder(Color.black, 10));

正如 MadProgrammer 所提到的，比画线更有效的方法是使用RoundRectangle2D。要使用它，请将所有 draw 行替换为

g2d.draw(new RoundRectangle2D.Double(x, y, width - 1, height - 1, gap, gap));

随意修改边框。这是使用Graphics2D的语法：

g2d.draw(new Line2D.Double((double)x1, (double)y1, (double)x2, (double)y2));

或

g2d.draw(new Line2D.Double(Point2D p1, Point2D p2));

我希望这会有所帮助！

Answer 3

simplest 是使用 LineBorder 类。

import java.awt.BorderLayout;
import java.awt.Color;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;

public class RoundedLineBorder extends JPanel {

  public RoundedLineBorder() {
    super(true);

    JLabel label = new JLabel("<html>Stack<br/>Overflow</html>");
    LineBorder line = new LineBorder(Color.blue, 1, true); // color, thickness, rounded
    label.setBorder(line);
    add(label, BorderLayout.CENTER);
  }

  public static void main(String s[]) {
    JFrame frame = new JFrame("Rounded Line Border");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(500, 200);
    frame.setContentPane(new RoundedLineBorder());
    frame.setVisible(true);
  }
} 

但结果并不是城里最好看的圆角;-)