Question

我在让MatteBorder使用从右向左的组件方向时遇到问题。下面的代码说明了问题。

我将一个JPanel放在另一个JPanel中。两个JPanel都有一个MatteBorder。内边框的厚度为10,10,10,10，而外边框的厚度为20,20,20,10（注意外边框是不对称的）。

如果JPanels的组件方向为LEFT_TO_RIGHT，那么一切看起来都不错;但如果方向为RIGHT_TO_LEFT，则边框重叠。

Overlapping borders

请考虑以下代码：

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

public class Xyzzy extends JFrame{
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                Xyzzy frame = new Xyzzy();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new FlowLayout(FlowLayout.RIGHT, 0, 5));
                frame.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT); 

                {
                    JPanel outer = new JPanel();
                    outer.setLayout(new FlowLayout(FlowLayout.RIGHT, 0, 5));
                    outer.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT); 
                    outer.setBorder(BorderFactory.createMatteBorder(20, 20, 20, 10, Color.black));

                    JPanel inner = new JPanel();
                    inner.setLayout(new FlowLayout(FlowLayout.RIGHT, 0, 5));
                    inner.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT); 
                    inner.setBorder(BorderFactory.createMatteBorder(10, 10, 10, 10, Color.red));

                    inner.add(Box.createRigidArea(new Dimension(10,10)));
                    outer.add(inner);
                    frame.add(outer);
                }

                {
                    JPanel outer = new JPanel();
                    outer.setLayout(new FlowLayout(FlowLayout.LEFT, 0, 5));
                    outer.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT); 
                    outer.setBorder(BorderFactory.createMatteBorder(20, 20, 20, 10, Color.blue));

                    JPanel inner = new JPanel();
                    inner.setLayout(new FlowLayout(FlowLayout.LEFT, 0, 5));
                    inner.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT); 
                    inner.setBorder(BorderFactory.createMatteBorder(10, 10, 10, 10, Color.yellow));

                    inner.add(Box.createRigidArea(new Dimension(10,10)));
                    outer.add(inner);
                    frame.add(outer);
                }

                frame.setSize(600, 600);
                frame.setVisible(true);
            }
        });
    }
}

代码的前半部分生成带有黑色和红色边框的RIGHT_TO_LEFT JPanels，后半部分生成带黄色和蓝色边框的LEFT_TO_RIGHT JPanels。如果您运行该程序，您将在蓝色边框内看到黄色边框，但红色边框与黑色边框重叠。

为什么？

Answer 1

注意：这是不答案 - 只是带代码的扩展评论： - ）

从OPs示例中删除一点，专注于FlowLayout-with-asym-border-in-RToL - 添加标签而不是刚性区域更好（对我来说:-)看看它在哪里位于。布局简直就是疯了......

public void run() {
    MatteBorderCO frame = new MatteBorderCO();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new FlowLayout()); 

    frame.add(createRToLPanel(50, 100, true));
    frame.add(createRToLPanel(100, 100, true));
    frame.add(createRToLPanel(100, 50, true));

    frame.setSize(600, 600);
    frame.setVisible(true);
}

private JPanel createRToLPanel(int leftInset, int rightInset, boolean matte) {
    JPanel outer = new JPanel();
    Border asymBorder = matte ? 
            BorderFactory.createMatteBorder(20, leftInset, 20, rightInset, Color.black) :
            BorderFactory.createEmptyBorder(20, leftInset, 20, rightInset)    ;
    outer.setBorder(BorderFactory.createCompoundBorder(
            asymBorder, BorderFactory.createLineBorder(Color.RED)
    ));

    JPanel inner = new JPanel();
    inner.setBackground(Color.YELLOW);
    inner.setBorder(BorderFactory.createLineBorder(Color.BLUE));
    inner.add(new JLabel("RToL"));
    outer.add(inner);
    outer.applyComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
    return outer;
}

修改

Culprit是flowLayout.moveComponents中位置的错误计算：

if (ltr) { m.setLocation(x, cy); } else { // RtoL orientation // here's the error: location is adjusted relative to the target width // without taking the insets into account ... m.setLocation(target.width - x - m.width, cy); }

修改2

删除了假定的＆＃34;简单＆＃34;修复 - 不够好; - ）

编辑3

无法抗拒，这里有一个FixedFlowLayout（正式未经测试，只是在上面的示例中使用，看起来很好用！）

public static class FixedFlowLayout extends FlowLayout { /** * C&p mostly - RToL border fix implemented. */ protected int moveComponents(Container target, int x, int y, int width, int height, int rowStart, int rowEnd, boolean ltr, boolean useBaseline, int[] ascent, int[] descent) { switch (getAlignment()) { case LEFT: x += ltr ? 0 : width; break; case CENTER: x += width / 2; break; case RIGHT: x += ltr ? width : 0; break; case LEADING: break; case TRAILING: x += width; break; } int maxAscent = 0; int nonbaselineHeight = 0; int baselineOffset = 0; if (useBaseline) { int maxDescent = 0; for (int i = rowStart; i < rowEnd; i++) { Component m = target.getComponent(i); if (m.isVisible()) { if (ascent[i] >= 0) { maxAscent = Math.max(maxAscent, ascent[i]); maxDescent = Math.max(maxDescent, descent[i]); } else { nonbaselineHeight = Math.max(m.getHeight(), nonbaselineHeight); } } } height = Math.max(maxAscent + maxDescent, nonbaselineHeight); baselineOffset = (height - maxAscent - maxDescent) / 2; } int right = target.getWidth() - target.getInsets().right - getHgap(); for (int i = rowStart; i < rowEnd; i++) { Component m = target.getComponent(i); if (m.isVisible()) { int cy; if (useBaseline && ascent[i] >= 0) { cy = y + baselineOffset + maxAscent - ascent[i]; } else { cy = y + (height - m.getHeight()) / 2; } if (ltr) { m.setLocation(x, cy); x += m.getWidth() + getHgap(); } else { m.setLocation(right - m.getWidth(), cy); right -= m.getWidth() + getHgap(); } } } return height; } /** * C&p, to be able to call the fixed moveComponent. */ @Override public void layoutContainer(Container target) { synchronized (target.getTreeLock()) { Insets insets = target.getInsets(); int maxwidth = target.getWidth() - (insets.left + insets.right + getHgap() * 2); int nmembers = target.getComponentCount(); int x = 0, y = insets.top + getVgap(); int rowh = 0, start = 0; boolean ltr = target.getComponentOrientation().isLeftToRight(); boolean useBaseline = getAlignOnBaseline(); int[] ascent = null; int[] descent = null; if (useBaseline) { ascent = new int[nmembers]; descent = new int[nmembers]; } for (int i = 0; i < nmembers; i++) { Component m = target.getComponent(i); if (m.isVisible()) { Dimension d = m.getPreferredSize(); m.setSize(d.width, d.height); if (useBaseline) { int baseline = m.getBaseline(d.width, d.height); if (baseline >= 0) { ascent[i] = baseline; descent[i] = d.height - baseline; } else { ascent[i] = -1; } } if ((x == 0) || ((x + d.width) <= maxwidth)) { if (x > 0) { x += getHgap(); } x += d.width; rowh = Math.max(rowh, d.height); } else { rowh = moveComponents(target, insets.left + getHgap(), y, maxwidth - x, rowh, start, i, ltr, useBaseline, ascent, descent); x = d.width; y += getVgap() + rowh; rowh = d.height; start = i; } } } moveComponents(target, insets.left + getHgap(), y, maxwidth - x, rowh, start, nmembers, ltr, useBaseline, ascent, descent); } } public FixedFlowLayout() { } public FixedFlowLayout(int align, int hgap, int vgap) { super(align, hgap, vgap); } public FixedFlowLayout(int align) { super(align); } }

Answer 2

我想我找到了解决问题的方法。（我的基础是kleopatra的修改代码。）

诀窍是在外部和内部JPanel之间插入一个中间JPanel。保持外部JPanel L-to-R并使中间和内部JPanels R-to-L。您还需要在外部面板的布局上指定零宽度间隙。

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

public class Xyzzy extends JFrame{
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    Xyzzy frame = new Xyzzy();
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.setLayout(new FlowLayout()); 

                    frame.add(createRToLPanel(50, 100, true));
                    frame.add(createRToLPanel(100, 100, true));
                    frame.add(createRToLPanel(100, 50, true));

                    frame.setSize(600, 600);
                    frame.setVisible(true);
                }


                private JPanel createRToLPanel(int leftInset, int rightInset, boolean matte) {
                    JPanel outer = new JPanel();
                    Border asymBorder = matte ? 
                        BorderFactory.createMatteBorder(20, leftInset, 20, rightInset, Color.black) :
                        BorderFactory.createEmptyBorder(20, leftInset, 20, rightInset)    ;
                    outer.setBorder(BorderFactory.createCompoundBorder(
                                        asymBorder, BorderFactory.createLineBorder(Color.RED)
                                        ));

                    JPanel intermediate = new JPanel();
                    outer.setLayout(new FlowLayout(FlowLayout.LEADING,0,0)); 
                    outer.add(intermediate);

                    JPanel inner = new JPanel();
                    inner.setBackground(Color.YELLOW);
                    inner.setBorder(BorderFactory.createLineBorder(Color.BLUE));
                    inner.add(new JLabel("RToL1"));
                    inner.add(new JLabel("RToL2"));

                    intermediate.add(inner);
                    intermediate.applyComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);

                    return outer;
                }


            });
    }
}

在这段代码中，我将两个JLabel添加到内部JPanel，以证明方向确实是R-to-L。

傻，傻。但如果这真的是一个错误，我可以用这种方式解决它。

MatteBorder不适用于从右到左的组件方向

2 个答案: