Use JTree as the table of contents

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

Code

class TableOfContentsTree extends JTree {
  private static final BasicStroke READER = new BasicStroke(
      1f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER, 1f, new float[] { 1f }, 0f);
  private boolean isSynth = false;
  public TableOfContentsTree(TreeModel model) {
    super(model);
  }
  @Override public void updateUI() {
    super.updateUI();
    setBorder(BorderFactory.createTitledBorder("JTree#paintComponent(...)"));
    isSynth = getUI().getClass().getName().contains("Synth");
  }
  private Rectangle getVisibleRowsRect() {
    Insets i = getInsets();
    Rectangle visRect = getVisibleRect();
    if(visRect.x == 0 && visRect.y == 0 && visRect.width == 0 &&
       visRect.height == 0 && getVisibleRowCount() > 0) {
      // The tree doesn't have a valid bounds yet. Calculate
      // based on visible row count.
      visRect.width = 1;
      visRect.height = getRowHeight() * getVisibleRowCount();
    }else{
      visRect.x -= i.left;
      visRect.y -= i.top;
    }
    // we should consider a non-visible area above
    Component component = SwingUtilities.getUnwrappedParent(this);
    if(component instanceof JViewport) {
      component = component.getParent();
      if(component instanceof JScrollPane) {
        JScrollPane pane = (JScrollPane) component;
        JScrollBar bar = pane.getHorizontalScrollBar();
        if(bar != null && bar.isVisible()) {
          int height = bar.getHeight();
          visRect.y -= height;
          visRect.height += height;
        }
      }
    }
    return visRect;
  }
  @Override public void paintComponent(Graphics g) {
    g.setColor(getBackground());
    g.fillRect(0,0,getWidth(),getHeight());
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D)g.create();
    FontMetrics fm = g.getFontMetrics();
    int pnmaxWidth = fm.stringWidth("000");
    Insets ins   = getInsets();
    Rectangle rect = getVisibleRowsRect();
    for(int i=0;i< getRowCount();i++) {
      Rectangle r = getRowBounds(i);
      if(rect.intersects(r)) {
        TreePath path = getPathForRow(i);
        TreeCellRenderer tcr = getCellRenderer();
        JComponent c = (JComponent)tcr;
        if(isSynth && isRowSelected(i)) {
          if(tcr instanceof DefaultTreeCellRenderer) {
            DefaultTreeCellRenderer renderer = (DefaultTreeCellRenderer)tcr;
            g2.setColor(renderer.getTextSelectionColor());
          }
        }else{
          g2.setColor(getForeground());
        }
        DefaultMutableTreeNode node = (DefaultMutableTreeNode)path.getLastPathComponent();
        Object o = node.getUserObject();
        if(o instanceof TableOfContents) {
          TableOfContents toc = (TableOfContents)o;
          String pn = "" + toc.page;
          int x = getWidth() -1 - fm.stringWidth(pn) - ins.right;
          //int y = (int)(0.5 + r.y + (r.height + fm.getAscent()) * 0.5);
          int y = r.y + c.getBaseline(r.width, r.height);
          g2.drawString(pn, x, y);

          int gap = 5;
          int x2  = getWidth() -1 - pnmaxWidth - ins.right;
          Stroke s = g2.getStroke();
          g2.setStroke(READER);
          g2.drawLine(r.x + r.width + gap, y, x2 - gap, y);
          g2.setStroke(s);
        }
      }
    }
    g2.dispose();
  }
}

References

• Use JTree as the table of contents(Japanese)