JTableの編集にセルより大きなセルエディタを使用

class IconTable extends JTable {
  private static final int XOFF = 4;
  private final JList<IconItem> editor;
  private final JComponent glassPane = new JComponent() {
    @Override public void setVisible(boolean flag) {
      super.setVisible(flag);
      setFocusTraversalPolicyProvider(flag);
      setFocusCycleRoot(flag);
    }

    @Override protected void paintComponent(Graphics g) {
      g.setColor(new Color(0x64_FF_FF_FF, true));
      g.fillRect(0, 0, getWidth(), getHeight());
      BufferedImage bufimg = new BufferedImage(
          getWidth(), getHeight(), BufferedImage.TYPE_INT_ARGB);
      Graphics2D g2 = bufimg.createGraphics();
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                          RenderingHints.VALUE_ANTIALIAS_ON);
      g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .15f));
      g2.setPaint(Color.BLACK);
      Rectangle r = editor.getBounds();
      for (int i = 0; i < XOFF; i++) {
        g2.fillRoundRect(
            r.x - i, r.y + XOFF, r.width + i + i, r.height - XOFF + i, 5, 5);
      }
      g2.dispose();
      g.drawImage(bufimg, 0, 0, null);
    }
  };

  protected IconTable(TableModel model, ListModel<IconItem> list) {
    super(model);
    setDefaultRenderer(Object.class, new IconTableCellRenderer());
    setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    initCellSize(50);
    addMouseListener(new MouseAdapter() {
      @Override public void mouseClicked(MouseEvent e) {
        startEditing();
      }
    });

    editor = new EditorFromList<>(list);
    editor.getInputMap(JComponent.WHEN_FOCUSED).put(
        KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0), "cancel-editing");
    editor.getActionMap().put("cancel-editing", new AbstractAction() {
      @Override public void actionPerformed(ActionEvent e) {
        cancelEditing();
      }
    });
    editor.addMouseListener(new MouseAdapter() {
      @Override public void mouseClicked(MouseEvent e) {
        Point p = e.getPoint();
        IconItem item = editor.getModel().getElementAt(editor.locationToIndex(p));
        setValueAt(item, getSelectedRow(), getSelectedColumn());
        cancelEditing();
      }
    });

    glassPane.addMouseListener(new MouseAdapter() {
      @Override public void mouseClicked(MouseEvent e) {
        cancelEditing();
      }
    });
    glassPane.setFocusTraversalPolicy(new DefaultFocusTraversalPolicy() {
      @Override public boolean accept(Component c) {
        return Objects.equals(c, editor);
      }
    });
    glassPane.add(editor);
    glassPane.setVisible(false);
  }

  private void initCellSize(int size) {
    setRowHeight(size);
    JTableHeader tableHeader = getTableHeader();
    tableHeader.setResizingAllowed(false);
    tableHeader.setReorderingAllowed(false);
    TableColumnModel m = getColumnModel();
    for (int i = 0; i < m.getColumnCount(); i++) {
      TableColumn col = m.getColumn(i);
      col.setMinWidth(size);
      col.setMaxWidth(size);
    }
    setBorder(BorderFactory.createLineBorder(Color.BLACK));
  }

  public void startEditing() {
    getRootPane().setGlassPane(glassPane);

    Dimension d = editor.getPreferredSize();
    editor.setSize(d);

    int sr = getSelectedRow();
    int sc = getSelectedColumn();
    Rectangle r = getCellRect(sr, sc, true);
    Point p = SwingUtilities.convertPoint(this, r.getLocation(), glassPane);
    p.translate((r.width - d.width) / 2, (r.height - d.height) / 2);
    editor.setLocation(p);

    glassPane.setVisible(true);
    editor.setSelectedValue(getValueAt(sr, sc), true);
    editor.requestFocusInWindow();
  }

  private void cancelEditing() {
    glassPane.setVisible(false);
  }
}