Swing/ColumnRules の変更点

---
category: swing
folder: ColumnRules
title: JSeparatorで段落罫線を描画する
tags: [JSeparator, JLayer, Border, GridLayout, GridBagLayout]
author: aterai
pubdate: 2021-08-16T01:18:16+09:00
description: GridLayoutなどで作成した列の間に罫線としてJSeparatorを描画します。
image: https://drive.google.com/uc?id=1n9PtghYLYyFH2fXRweyIthvJhNYfa2Mz
---
* 概要 [#summary]
`GridLayout`などで作成した列の間に罫線として`JSeparator`を描画します。

#download(https://drive.google.com/uc?id=1n9PtghYLYyFH2fXRweyIthvJhNYfa2Mz)

* サンプルコード [#sourcecode]
#code(link){{
JPanel p1 = new JPanel(new GridBagLayout());
p1.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
GridBagConstraints c = new GridBagConstraints();
c.anchor = GridBagConstraints.CENTER;
c.gridheight = 1;
c.gridwidth = 1;
c.gridx = 0;
c.gridy = 0;
c.weightx = 1.0;
c.weighty = 1.0;

c.fill = GridBagConstraints.BOTH;
p1.add(new JLabel("left", SwingConstants.CENTER), c);

c.gridx = 1;
c.weightx = 0.0;
c.fill = GridBagConstraints.VERTICAL;
p1.add(new JSeparator(SwingConstants.VERTICAL), c);

c.gridx = 2;
c.weightx = 1.0;
c.fill = GridBagConstraints.BOTH;
p1.add(new JLabel("right", SwingConstants.CENTER), c);

JPanel p2 = new JPanel(new GridLayout(0, 2, 5, 5));
p2.setBorder(BorderFactory.createCompoundBorder(
    BorderFactory.createEmptyBorder(5, 5, 5, 5), new ColumnRulesBorder()));

JPanel p3 = new JPanel(new GridLayout(0, 2, 5, 5));
p3.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));

Stream.of(p2, p3).forEach(p -> {
  p.add(new JLabel("left", SwingConstants.CENTER));
  p.add(new JLabel("right", SwingConstants.CENTER));
});
}}

* 解説 [#explanation]
- `GridBagLayout`
-- `JPanel`に`3`列の`GridBagLayout`を設定
-- 中央の余分の水平スペースを分配を`0`に設定して縦`JSeparator`を追加
--- `JSeparator`がすこし左にずれる？
-- [[Componentの3列配置、中央幅固定、左右均等引き伸ばしを行うLayoutManagerを作成する>Swing/ThreeColumnLayout]]

- `GridLayout + Border`
-- `JPanel`に`2`列の`GridLayout`を設定
-- コンポーネントの中央に`SwingUtilities.paintComponent(...)`メソッドを使用して`JSeparator`のコピーを描画する`Border`を作成
-- `CompoundBorder`で元の`Border`と組み合わせて`JPanel`に設定して段落罫線を描画
-- [[JMenuから開くポップアップウィンドウのレイアウトを2列に変更する>Swing/TwoColumnsMenu]]

#code{{
class ColumnRulesBorder implements Border {
  private final Insets insets = new Insets(0, 0, 0, 0);
  private final JSeparator separator = new JSeparator(SwingConstants.VERTICAL);
  private final Container renderer = new JPanel();

  @Override public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
  @Override public void paintBorder(
      Component c, Graphics g, int x, int y, int width, int height) {
    if (c instanceof JComponent) {
      Rectangle r = SwingUtilities.calculateInnerArea((JComponent) c, null);
      int sw = separator.getPreferredSize().width;
      int sh = r.height;
      int sx = (int) (r.getCenterX() - sw / 2d);
      int sy = (int) r.getMinY();
      Graphics2D g2 = (Graphics2D) g.create();
      SwingUtilities.paintComponent(g2, separator, renderer, sx, sy, sw, sh);
      g2.dispose();
    }
  }

  @Override public Insets getBorderInsets(Component c) {
    return insets;
  }

  @Override public boolean isBorderOpaque() {
    return true;
  }
}
}}

- `GridLayout + JLayer`
-- `JPanel`に`2`列の`GridLayout`を設定
-- コンポーネントの中央に`SwingUtilities.paintComponent(...)`メソッドを使用して`JSeparator`のコピーを描画する`LayerUI`を作成
-- `JLayer`で`JPanel`をラップして段落罫線を描画
-- [[JSplitPaneのDividerを円形半透明のつまみに変更して中央に配置する>Swing/TranslucentThumbDivider]]

#code{{
class ColumnRulesLayerUI extends LayerUI<JComponent> {
  private final JSeparator separator = new JSeparator(SwingConstants.VERTICAL);
  private final Container renderer = new JPanel();

  @Override public void paint(Graphics g, JComponent c) {
    super.paint(g, c);
    if (c instanceof JLayer) {
      JComponent tc = (JComponent) ((JLayer<?>) c).getView();
      Rectangle r = SwingUtilities.calculateInnerArea(tc, null);
      int sw = separator.getPreferredSize().width;
      int sh = r.height;
      int sx = (int) (r.getCenterX() - sw / 2d);
      int sy = (int) r.getMinY();
      Graphics2D g2 = (Graphics2D) g.create();
      SwingUtilities.paintComponent(g2, separator, renderer, sx, sy, sw, sh);
      g2.dispose();
    }
  }
}
}}

* 参考リンク [#reference]
- [[Componentの3列配置、中央幅固定、左右均等引き伸ばしを行うLayoutManagerを作成する>Swing/ThreeColumnLayout]]
- [[JMenuから開くポップアップウィンドウのレイアウトを2列に変更する>Swing/TwoColumnsMenu]]
- [[JSplitPaneのDividerを円形半透明のつまみに変更して中央に配置する>Swing/TranslucentThumbDivider]]

* コメント [#comment]
#comment
#comment