带圆角和透明度的边框

Question

以下屏幕截图显示了 TextBubbleBorder 1的测试。我想让矩形外部组件的角完全透明并显示其下方的任何组件。我找到了一种方法，通过在 Graphics2D 实例上设置 Clip （代表圆角外的区域）来将标签的 BG 颜色限制在“边界内”并调用 clearRect() 。这可以在 Label 1 中看到。

但是，当父面板上有红色 BG（或任何非标准颜色）时，您会看到这种方法的缺点。角落默认为默认面板颜色（最容易在 Panel 2 中看到）。

最终我希望这适用于父容器中的非标准颜色，但部分灵感来自 我需要做什么才能使用渐变涂料复制此组件？

有人知道让这些角落透明的方法吗？

 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 是为 带有背景图像的 JTextArea 的内部填充 设计的（& 最终使用 JLabel 因为文本区域由于上述原因而变得一团糟），通过指定 pointerSize 0 我们最终得到一个“圆角矩形”。

原文由 Andrew Thompson 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

注意：此代码中存在一个剪辑错误，已在对 paintComponent() is drawing on other components 的接受答案中修复。如果合并了“剪辑错误修复”，则仅应将其视为解决方案。

---

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

请参阅源代码中的这一点，它正确显示为：

 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);
    }
}

原文由 Andrew Thompson 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

尝试这个：

   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
     }
  };

通过我的测试：

   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：

原文由 BackSlash 发布，翻译遵循 CC BY-SA 3.0 许可协议