带有圆角和透明度的边框

Question

以下截图显示了对TextBubbleBorder¹的测试。我想让组件的角落完全透明，并显示在其下方的任何组件。我找到了一种方法，通过在Graphics2D实例上设置Clip（表示圆角外的区域）并调用clearRect()来限制标签的BG颜色为“边框内部”。这可以在Label 1中看到。

然而，当父容器面板有红色背景（或任何非标准颜色）时，您可以看到此方法的缺点。角落默认为默认面板颜色（在面板2中最容易看到）。

最终，我希望这适用于父容器中的非标准颜色，但这部分是受我需要做什么才能使用渐变涂料复制此组件？启发的。

有人知道如何使这些角落透明吗？

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

public class BorderTest {

    public static void main(String[] args) {
        Runnable r = new Runnable() {

            @Override
            public void run() {
                JPanel gui = new JPanel(new GridLayout(1,0,5,5));
                gui.setBorder(new EmptyBorder(10,10,10,10));
                gui.setBackground(Color.RED);

                AbstractBorder brdr = new TextBubbleBorder(Color.BLACK,2,16,0);

                JLabel l1 = new JLabel("Label 1");
                l1.setBorder(brdr);
                gui.add(l1);

                JLabel l2 = new JLabel("Label 2");
                l2.setBorder(brdr);
                l2.setBackground(Color.YELLOW);
                l2.setOpaque(true);
                gui.add(l2);

                JPanel p1 = new JPanel();
                p1.add(new JLabel("Panel 1"));
                p1.setBorder(brdr);
                p1.setOpaque(false);
                gui.add(p1);

                JPanel p2 = new JPanel();
                p2.add(new JLabel("Panel 2"));
                p2.setBorder(brdr);
                gui.add(p2);

                JOptionPane.showMessageDialog(null, gui);
            }
        };
        // Swing GUIs should be created and updated on the EDT
        // http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
        SwingUtilities.invokeLater(r);
    }

}

class TextBubbleBorder extends AbstractBorder {

    private Color color;
    private int thickness = 4;
    private int radii = 8;
    private int pointerSize = 7;
    private Insets insets = null;
    private BasicStroke stroke = null;
    private int strokePad;
    private int pointerPad = 4;
    RenderingHints hints;

    TextBubbleBorder(
            Color color) {
        new TextBubbleBorder(color, 4, 8, 7);
    }

    TextBubbleBorder(
            Color color, int thickness, int radii, int pointerSize) {
        this.thickness = thickness;
        this.radii = radii;
        this.pointerSize = pointerSize;
        this.color = color;

        stroke = new BasicStroke(thickness);
        strokePad = thickness / 2;

        hints = new RenderingHints(
                RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);

        int pad = radii + strokePad;
        int bottomPad = pad + pointerSize + strokePad;
        insets = new Insets(pad, pad, bottomPad, pad);
    }

    @Override
    public Insets getBorderInsets(Component c) {
        return insets;
    }

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

    @Override
    public void paintBorder(
            Component c,
            Graphics g,
            int x, int y,
            int width, int height) {

        Graphics2D g2 = (Graphics2D) g;

        int bottomLineY = height - thickness - pointerSize;

        RoundRectangle2D.Double bubble = new RoundRectangle2D.Double(
                0 + strokePad,
                0 + strokePad,
                width - thickness,
                bottomLineY,
                radii,
                radii);

        Polygon pointer = new Polygon();

        // left point
        pointer.addPoint(
                strokePad + radii + pointerPad,
                bottomLineY);
        // right point
        pointer.addPoint(
                strokePad + radii + pointerPad + pointerSize,
                bottomLineY);
        // bottom point
        pointer.addPoint(
                strokePad + radii + pointerPad + (pointerSize / 2),
                height - strokePad);

        Area area = new Area(bubble);
        area.add(new Area(pointer));

        g2.setRenderingHints(hints);

        Area spareSpace = new Area(new Rectangle(0, 0, width, height));
        spareSpace.subtract(area);
        g2.setClip(spareSpace);
        g2.clearRect(0, 0, width, height);
        g2.setClip(null);

        g2.setColor(color);
        g2.setStroke(stroke);
        g2.draw(area);
    }
}

1. 虽然 TextBubbleBorder 最初是为 使用背景图像的 JTextArea 的内部填充 设计的（并最终使用了 JLabel，因为上述原因使文本区域混乱），但通过将 pointerSize 指定为 0，我们最终得到一个“圆角矩形”。
   
   

- Andrew Thompson

Answer 1

注意：在这段代码中有一个裁剪错误，已在paintComponent() is drawing on other components的被接受的答案中得到修复。如果“裁剪错误修复”被纳入考虑，则应将其视为解决方案。

---

// Paint the BG color of the parent, everywhere outside the clip
// of the text bubble.

请查看代码中的此处以查看正确显示的源代码：

import java.awt.*;
import java.awt.image.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.border.*;

public class BorderTest {

    public static void main(String[] args) {
        Runnable r = new Runnable() {

            @Override
            public void run() {
                JPanel gui = new JPanel(new GridLayout(2,0,5,5));
                gui.setBorder(new EmptyBorder(10,10,10,10));
                gui.setBackground(Color.RED);

                AbstractBorder brdrLeft = new TextBubbleBorder(Color.BLACK,2,16,16);
                AbstractBorder brdrRight = new TextBubbleBorder(Color.BLACK,2,16,16,false);

                JLabel l1 = new JLabel("Label 1");
                l1.setBorder(brdrRight);
                gui.add(l1);

                JLabel l2 = new JLabel("Label 2");
                l2.setBorder(brdrLeft);
                l2.setBackground(Color.YELLOW);
                l2.setOpaque(true);
                gui.add(l2);

                JPanel p1 = new JPanel();
                p1.add(new JLabel("Panel 1"));
                p1.setBorder(brdrRight);
                p1.setOpaque(false);
                gui.add(p1);

                JPanel p2 = new JPanel();
                p2.add(new JLabel("Panel 2"));
                p2.setBorder(brdrLeft);
                gui.add(p2);

                JOptionPane.showMessageDialog(null, gui);
            }
        };
        // Swing GUIs should be created and updated on the EDT
        // http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
        SwingUtilities.invokeLater(r);
    }

}

class TextBubbleBorder extends AbstractBorder {

    private Color color;
    private int thickness = 4;
    private int radii = 8;
    private int pointerSize = 7;
    private Insets insets = null;
    private BasicStroke stroke = null;
    private int strokePad;
    private int pointerPad = 4;
    private boolean left = true;
    RenderingHints hints;

    TextBubbleBorder(
            Color color) {
        this(color, 4, 8, 7);
    }

    TextBubbleBorder(
            Color color, int thickness, int radii, int pointerSize) {
        this.thickness = thickness;
        this.radii = radii;
        this.pointerSize = pointerSize;
        this.color = color;

        stroke = new BasicStroke(thickness);
        strokePad = thickness / 2;

        hints = new RenderingHints(
                RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);

        int pad = radii + strokePad;
        int bottomPad = pad + pointerSize + strokePad;
        insets = new Insets(pad, pad, bottomPad, pad);
    }

    TextBubbleBorder(
            Color color, int thickness, int radii, int pointerSize, boolean left) {
        this(color, thickness, radii, pointerSize);
        this.left = left;
    }

    @Override
    public Insets getBorderInsets(Component c) {
        return insets;
    }

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

    @Override
    public void paintBorder(
            Component c,
            Graphics g,
            int x, int y,
            int width, int height) {

        Graphics2D g2 = (Graphics2D) g;

        int bottomLineY = height - thickness - pointerSize;

        RoundRectangle2D.Double bubble = new RoundRectangle2D.Double(
                0 + strokePad,
                0 + strokePad,
                width - thickness,
                bottomLineY,
                radii,
                radii);

        Polygon pointer = new Polygon();

        if (left) {
            // left point
            pointer.addPoint(
                    strokePad + radii + pointerPad,
                    bottomLineY);
            // right point
            pointer.addPoint(
                    strokePad + radii + pointerPad + pointerSize,
                    bottomLineY);
            // bottom point
            pointer.addPoint(
                    strokePad + radii + pointerPad + (pointerSize / 2),
                    height - strokePad);
        } else {
            // left point
            pointer.addPoint(
                    width - (strokePad + radii + pointerPad),
                    bottomLineY);
            // right point
            pointer.addPoint(
                    width - (strokePad + radii + pointerPad + pointerSize),
                    bottomLineY);
            // bottom point
            pointer.addPoint(
                    width - (strokePad + radii + pointerPad + (pointerSize / 2)),
                    height - strokePad);
        }

        Area area = new Area(bubble);
        area.add(new Area(pointer));

        g2.setRenderingHints(hints);

        // Paint the BG color of the parent, everywhere outside the clip
        // of the text bubble.
        Component parent  = c.getParent();
        if (parent!=null) {
            Color bg = parent.getBackground();
            Rectangle rect = new Rectangle(0,0,width, height);
            Area borderRegion = new Area(rect);
            borderRegion.subtract(area);
            g2.setClip(borderRegion);
            g2.setColor(bg);
            g2.fillRect(0, 0, width, height);
            g2.setClip(null);
        }

        g2.setColor(color);
        g2.setStroke(stroke);
        g2.draw(area);
    }
}

- Andrew Thompson

---

这个问题从您的代码中借鉴而来，并发现当一个使用这个边框的组件在滚动窗格中使用时，剪切代码存在问题。我认为我的解决方案在这里也适用。 - camickr

Answer 2

试试这个：

  JPanel p = new JPanel() {
     @Override
     protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Dimension arcs = new Dimension(15,15); //Border corners arcs {width,height}, change this to whatever you want
        int width = getWidth();
        int height = getHeight();
        Graphics2D graphics = (Graphics2D) g;
        graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);


        //Draws the rounded panel with borders.
        graphics.setColor(getBackground());
        graphics.fillRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height);//paint background
        graphics.setColor(getForeground());
        graphics.drawRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height);//paint border
     }
  };

使用我的测试：

  JFrame f = new JFrame();
  f.setLayout(null);
  f.setDefaultCloseOperation(3);
  f.setSize(500, 500);
  JPanel p = new JPanel() {
     @Override
     protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Dimension arcs = new Dimension(15,15);
        int width = getWidth();
        int height = getHeight();
        Graphics2D graphics = (Graphics2D) g;
        graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);


        //Draws the rounded opaque panel with borders.
        graphics.setColor(getBackground());
        graphics.fillRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height);//paint background
        graphics.setColor(getForeground());
        graphics.drawRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height);//paint border
     }
  };
  p.setBounds(10,10,100,30);
  p.setOpaque(false);
  f.getContentPane().setBackground(Color.red);
  f.add(p);
  f.show();

结果是：

- BackSlash

Answer 3

感谢 @BackSlash，这个方案简单易懂。我对此进行了扩展，使其更具可重用性。这还允许在构造函数中设置背景颜色。我还展示了如何制作一个有趣的圆形面板。

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

public class RoundedPanelExample extends JFrame
{
    public RoundedPanelExample()
    {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setTitle("Rounded Panel Example");
        setResizable(true);
        setDefaultLookAndFeelDecorated(true);
        setSize(500, 500);

        Container pane = getContentPane();
        pane.setLayout(null);
        pane.setBackground(Color.LIGHT_GRAY);

        JPanel p1 = new RoundedPanel(10, Color.CYAN);
        p1.setBounds(10,10,100,60);
        p1.setOpaque(false);
        pane.add(p1);

        JPanel p2 = new RoundedPanel(15, Color.RED);
        p2.setBounds(150,10,50,50);
        p2.setOpaque(false);
        pane.add(p2);

        JPanel p3 = new RoundedPanel(30);
        p3.setBounds(230,10,100,150);
        p3.setOpaque(false);
        pane.add(p3);

        JPanel p4 = new RoundedPanel(20);
        p4.setBounds(10,200,100,100);
        p4.setBackground(Color.GREEN);
        p4.setOpaque(false);
        pane.add(p4);

        JPanel p5 = new RoundedPanel(200);
        p5.setBounds(150,200,200,200);
        p5.setBackground(Color.BLUE);
        p5.setOpaque(false);
        pane.add(p5);
    }

    public static void main(String[] args) 
    {
        RoundedPanelExample gui = new RoundedPanelExample();
        gui.setVisible(true);
    }

    class RoundedPanel extends JPanel
    {
        private Color backgroundColor;
        private int cornerRadius = 15;

        public RoundedPanel(LayoutManager layout, int radius) {
            super(layout);
            cornerRadius = radius;
        }

        public RoundedPanel(LayoutManager layout, int radius, Color bgColor) {
            super(layout);
            cornerRadius = radius;
            backgroundColor = bgColor;
        }

        public RoundedPanel(int radius) {
            super();
            cornerRadius = radius;
        }

        public RoundedPanel(int radius, Color bgColor) {
            super();
            cornerRadius = radius;
            backgroundColor = bgColor;
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Dimension arcs = new Dimension(cornerRadius, cornerRadius);
            int width = getWidth();
            int height = getHeight();
            Graphics2D graphics = (Graphics2D) g;
            graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

            //Draws the rounded panel with borders.
            if (backgroundColor != null) {
                graphics.setColor(backgroundColor);
            } else {
                graphics.setColor(getBackground());
            }
            graphics.fillRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height); //paint background
            graphics.setColor(getForeground());
            graphics.drawRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height); //paint border
        }
    }
}

- Ryan

Answer 4

可能的更便宜的替代方案

public class RoundedLabel extends JLabel {
  private final Rectangle rv = new Rectangle();

  @Override
  public void updateUI() {
    super.updateUI();
    setBorder(new EmptyBorder(1, 3, 1, 3));
  }

  @Override
  protected void paintComponent(Graphics g) {
    getBounds(rv);
    var g2 = (Graphics2D) g;
    g2.setColor(getBackground());
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    g2.fillRoundRect(rv.x, rv.y, rv.width, rv.height, 8, 8);
    super.paintComponent(g);
  }
}

- bric3