Question

我只需要在组件的单侧上创建一个圆角边框。

此代码创建一个圆角边框：

  new LineBorder(Color.RED, 3, true)

我看过this thread，它向您展示了如何创建可以仅在组件的一侧使用的遮罩边框，但是遮罩边框不会被舍入。

是否可以仅在一侧设置圆形边框？

修改

我尝试过使用复合边框：

    cell.setBorder(BorderFactory.createCompoundBorder(
        new LineBorder(borderColor, 3, true),
        BorderFactory.createMatteBorder(0, 3, 0, 0, Color.black)));

但它不起作用......

Answer 1

您可以覆盖LineBorder的方法并在那里绘制所需的全部内容来自LineBorder的来源

    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        Color oldColor = g.getColor();
        int i;

    /// PENDING(klobad) How/should do we support Roundtangles?
        g.setColor(lineColor);
        for(i = 0; i < thickness; i++)  {
        if(!roundedCorners)
                g.drawRect(x+i, y+i, width-i-i-1, height-i-i-1);
        else
SET CLIP HERE TO DRAW ONLY NECESSARY PART
                g.drawRoundRect(x+i, y+i, width-i-i-1, height-i-i-1, thickness, thickness);
        }
        g.setColor(oldColor);
    }

Answer 2

LineBorder仅支持圆角或不圆角。复合边框（如JavaDoc所述）使用一个边框用于外部，一个边框用于内部，因此不区分左/右或上/下。

我担心您要么编写自己的Border实现，要么寻找已经由其他人（外部库）创建的实现。

Answer 3

以下是有关如何使用Graphics2D#clipRect()的示例。此代码只保留两个正确的圆角，并在左侧有正常的边框。如上所述，您必须在自定义LineBorder中使用此代码。

Graphics2D g2d = (Graphics2D) g;

g2d.clipRect(150, 10, 100, 100);
g2d.draw(new RoundRectangle2D.Double(100, 10, 80, 30, 15, 15));

g2d.setClip(null);
g2d.clipRect(100, 10, 50, 100);
g2d.draw(new Rectangle2D.Double(100, 10, 80, 30));

Answer 4

public static final int TOP_LEFT = 1;
public static final int TOP_RIGHT = 2;
public static final int BOTTOM_LEFT = 4;
public static final int BOTTOM_RIGHT = 8;
public static final int ALL_CORNERS = TOP_LEFT + TOP_RIGHT + BOTTOM_LEFT + BOTTOM_RIGHT;

public static void drawRoundRect(Graphics g, Color fillColor, Color borderColor, int x, int y, int width, int height, int radius, int cornerMask)
{
    // // XXX Old code (without selectively disabled round corners):
    // if (fillColor != null)
    // {
    // og.setColor(fillColor);
    // og.fillRoundRect(x, y, width - 1, height - 1, radius, radius);
    // }
    // if (borderColor != null && !borderColor.equals(fillColor))
    // {
    // og.setColor(borderColor);
    // og.drawRoundRect(x, y, width - 1, height - 1, radius, radius);
    // }
    radius += radius % 2; // so we don't have to deal with rounding issues for odd numbers
    int radiusHalf = radius / 2;
    width--;
    height--;
    if (fillColor != null)
    {
        g.setColor(fillColor);
        // og.fillRoundRect(x, y, width - 1, height - 1, radius, radius);
        if ((cornerMask & TOP_LEFT) > 0)
        {
            g.fillArc(x, y, radius, radius, 90, 90);
        }
        else
        {
            g.fillRect(x, y, radiusHalf, radiusHalf);
        }
        if ((cornerMask & TOP_RIGHT) > 0)
        {
            g.fillArc(x + width - radius, y, radius, radius, 0, 90);
        }
        else
        {
            g.fillRect(x + width - radiusHalf, y, radiusHalf, radiusHalf);
        }
        if ((cornerMask & BOTTOM_RIGHT) > 0)
        {
            g.fillArc(x + width - radius, y + height - radius, radius, radius, 270, 90);
        }
        else
        {
            g.fillRect(x + width - radiusHalf, y + height - radiusHalf, radiusHalf, radiusHalf);
        }
        if ((cornerMask & BOTTOM_LEFT) > 0)
        {
            g.fillArc(x, y + height - radius, radius, radius, 180, 90);
        }
        else
        {
            g.fillRect(x, y + height - radiusHalf, radiusHalf, radiusHalf);
        }

        g.fillRect(x + radiusHalf, y, width - radius, radiusHalf);
        g.fillRect(x + radiusHalf, y + height - radiusHalf, width - radius, radiusHalf);
        g.fillRect(x, y + radiusHalf, radiusHalf, height - radius);
        g.fillRect(x + width - radiusHalf, y + radiusHalf, radiusHalf, height - radius);
        g.fillRect(x + radiusHalf, y + radiusHalf, width - radius, height - radius);
    }
    if (borderColor != null && !borderColor.equals(fillColor))
    {
        g.setColor(borderColor);

        // XXX: there are problems with this when using semi-transparent colors + borderSize > 1
        // XXX: this could be changed to to use ONE draw action using drawShape with GeneralPath.curveTo()
        // XXX: this then could also be used to FILL the shape (see above)
        if ((cornerMask & TOP_LEFT) > 0)
        {
            g.drawArc(x, y, radius, radius, 90, 90);
        }
        else
        {
            g.drawLine(x, y, x + radiusHalf, y);
            g.drawLine(x, y, x, y + radiusHalf);
        }
        if ((cornerMask & TOP_RIGHT) > 0)
        {
            g.drawArc(x + width - radius, y, radius, radius, 0, 90);
        }
        else
        {
            g.drawLine(x + width - radiusHalf, y, x + width, y);
            g.drawLine(x + width, y, x + width, y + radiusHalf);
        }
        if ((cornerMask & BOTTOM_RIGHT) > 0)
        {
            g.drawArc(x + width - radius, y + height - radius, radius, radius, 270, 90);
        }
        else
        {
            g.drawLine(x + width - radiusHalf, y + height, x + width, y + height);
            g.drawLine(x + width, y + height - radiusHalf, x + width, y + height);
        }
        if ((cornerMask & BOTTOM_LEFT) > 0)
        {
            g.drawArc(x, y + height - radius, radius, radius, 180, 90);
        }
        else
        {
            g.drawLine(x, y + height, x + radiusHalf, y + height);
            g.drawLine(x, y + height - radiusHalf, x, y + height);
        }

        g.drawLine(x + radiusHalf, y, x + width - radiusHalf, y); // top
        g.drawLine(x + width, y + radiusHalf, x + width, y + height - radiusHalf); // right
        g.drawLine(x + radiusHalf, y + height, x + width - radiusHalf, y + height); // bottom
        g.drawLine(x, y + radiusHalf, x, y + height - radiusHalf); // left
    }
}

Answer 5

这是一个例子，

JPanel content = new JPanel(); content.setBorder(BorderFactory.createEmptyBorder(1,30,1,1));

圆形边框一边只有java

5 个答案: