Wraps JPanel child components horizontally and dynamically expands their horizontal spacing

• download example.jar
• download src.zip
• repository

Code

class ScrollableWrapLayout extends FlowLayout {
  private final int fixedHorizontalGap;

  protected ScrollableWrapLayout(int align, int hgap, int vgap) {
    super(align, hgap, vgap);
    fixedHorizontalGap = hgap;
  }

  private int getPreferredHorizontalGap(Container target) {
    Insets insets = target.getInsets();
    int columns = 0;
    int width = target.getWidth();
    if (target.getParent() instanceof JViewport) {
      width = target.getParent().getBounds().width;
    }
    width -= insets.left + insets.right + fixedHorizontalGap * 2;
    for (int i = 0; i < target.getComponentCount(); i++) {
      Component m = target.getComponent(i);
      if (m.isVisible()) {
        Dimension d = m.getPreferredSize();
        if (width - d.width - fixedHorizontalGap < 0) {
          columns = i;
          break;
        }
        width -= d.width + fixedHorizontalGap;
      }
    }
    return fixedHorizontalGap + width / columns;
  }

  @Override public void layoutContainer(Container target) {
    setHgap(getPreferredHorizontalGap(target));
    super.layoutContainer(target);
  }

  @Override public Dimension preferredLayoutSize(Container target) {
    Dimension dim = super.preferredLayoutSize(target);
    synchronized (target.getTreeLock()) {
      if (target.getParent() instanceof JViewport) {
        dim.width = target.getParent().getBounds().width;
        for (int i = 0; i < target.getComponentCount(); i++) {
          Component m = target.getComponent(i);
          if (m.isVisible()) {
            Dimension d = m.getPreferredSize();
            dim.height = Math.max(dim.height, d.height + m.getY());
          }
        }
      }
      return dim;
    }
  }
}

References

• Wrap Layout « Java Tips Weblog
• Java Swing Tips: using rubber band selection in JList
• Wraps JPanel child components horizontally and dynamically expands their horizontal spacing(Japanese)

Breadcrumb Navigation with JRadioButton

• download example.jar
• download src.zip
• repository

Code

private static JComponent makeBreadcrumbList(int overlap, List<String> list) {
  JPanel p = new JPanel(new FlowLayout(FlowLayout.LEADING, -overlap, 0));
  p.setBorder(BorderFactory.createEmptyBorder(4, overlap + 4, 4, 4));
  p.setOpaque(false);
  ButtonGroup bg = new ButtonGroup();
  for (String title: list) {
    AbstractButton b = makeButton(title, Color.PINK);
    p.add(b);
    bg.add(b);
  }
  return p;
}

References

• Breadcrumb Navigation with JRadioButton(Japanese)

Creating a Custom Layout Manager

• download example.jar
• download src.zip
• repository

Code

final double A2 = 4.0;
panel2.setLayout(new FlowLayout() {
  @Override public void layoutContainer(Container target) {
    synchronized(target.getTreeLock()) {
      Insets insets = target.getInsets();
      int nmembers  = target.getComponentCount();
      if(nmembers<=0) return;
      int vgap = getVgap();
      int hgap = getHgap();
      int rowh = (target.getHeight()-(insets.top+insets.bottom+vgap*2))/nmembers;
      int x = insets.left + hgap;
      int y = insets.top  + vgap;
      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);
          m.setLocation(x, y);
          y += (vgap + Math.min(rowh, d.height));
          x = (int)(A2 * Math.sqrt(y));
        }
      }
    }
  }
});

References

• Creating a Custom Layout Manager(Japanese)