概要

JTreeのノード間の接続線の色、太さなどを変更します。

サンプルコード

UIManager.put("Tree.paintLines", Boolean.TRUE);
UIManager.put("Tree.lineTypeDashed", Boolean.TRUE);
UIManager.put("Tree.line", Color.GREEN);
UIManager.put("Tree.hash", Color.RED);

JTree tree0 = new JTree();

JTree tree1 = new JTree();
tree1.putClientProperty("JTree.lineStyle", "Horizontal");

JTree tree2 = new JTree();
tree2.setUI(new BasicTreeUI() {
  private final Stroke horizontalLine = new BasicStroke(2f);
  private final Stroke verticalLine = new BasicStroke(5f);
  @Override public Color getHashColor() {
    return Color.BLUE;
  }
  @Override protected void paintHorizontalPartOfLeg(
      Graphics g, Rectangle clipBounds, Insets insets,
      Rectangle bounds, TreePath path, int row,
      boolean isExpanded, boolean hasBeenExpanded, boolean isLeaf) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setStroke(horizontalLine);
    super.paintHorizontalPartOfLeg(
        g2, clipBounds, insets, bounds, path, row,
        isExpanded, hasBeenExpanded, isLeaf);
    g2.dispose();
  }
  @Override protected void paintVerticalPartOfLeg(
      Graphics g, Rectangle clipBounds, Insets insets, TreePath path) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setStroke(verticalLine);
    super.paintVerticalPartOfLeg(g2, clipBounds, insets, path);
    g2.dispose();
  }
});
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解説

  • lineTypeDashed
    • UIManager.put("Tree.lineTypeDashed", Boolean.TRUE);を設定して接続線を点線に変更
    • UIManager.put("Tree.hash", Color.RED);で線色を変更可能
  • lineStyle
    • tree1.putClientProperty("JTree.lineStyle", "Horizontal");を設定して親ノードの上下に水平線を表示するスタイルに変更
    • UIManager.put("Tree.line", Color.GREEN);で水平線の線色を変更可能
      • 接続線の線色には影響しない
  • BasicTreeUI
    • BasicTreeUI#paintHorizontalPartOfLeg(...)BasicTreeUI#paintVerticalPartOfLeg(...)をオーバーライドして、接続線の太さを変更
    • 接続線の色は、BasicTreeUI#getHashColor()をオーバーライドして変更
    • UIManager.put("Tree.lineTypeDashed", Boolean.TRUE);の設定などは無視される
    • UIManager.put("Tree.lineTypeDashed", Boolean.TRUE);の場合、Graphics2D#setStroke(...)の設定が無効になる場合がある?
    • BasicTreeUIは点線の描画にBasicStrokeを使用せず、以下のように1pxの線を描画しているため?
      // This method is slow -- revisit when Java2D is ready.
      // assumes y1 <= y2
      protected void drawDashedVerticalLine(Graphics g, int x, int y1, int y2) {
        // Drawing only even coordinates helps join line segments so they
        // appear as one line.  This can be defeated by translating the
        // Graphics by an odd amount.
        y1 += (y1 % 2);
        for (int y = y1; y <= y2; y+=2) {
          g.drawLine(x, y, x, y);
        }
      }
      

参考リンク

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