Add a header to JPopupMenu to enable repositioning by mouse dragging

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

Code

class PopupHeaderMouseListener extends MouseAdapter {
  private final Point startPt = new Point();

  @Override public void mousePressed(MouseEvent e) {
    if (SwingUtilities.isLeftMouseButton(e)) {
      startPt.setLocation(e.getPoint());
    }
  }

  @Override public void mouseDragged(MouseEvent e) {
    Component c = e.getComponent();
    Window w = SwingUtilities.getWindowAncestor(c);
    if (w != null && SwingUtilities.isLeftMouseButton(e)) {
      if (w.getType() == Window.Type.POPUP) { // Popup$HeavyWeightWindow
        Point pt = e.getLocationOnScreen();
        w.setLocation(pt.x - startPt.x, pt.y - startPt.y);
      } else { // Popup$LightWeightWindow
        Container popup = SwingUtilities.getAncestorOfClass(JPopupMenu.class, c);
        Point pt = popup.getLocation();
        popup.setLocation(pt.x - startPt.x + e.getX(), pt.y - startPt.y + e.getY());
      }
    }
  }
}

References

• Add a header to JPopupMenu to enable repositioning by mouse dragging(Japanese)

Make the editable JTextArea scrollable beyond its last line

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

Code

// https://stackoverflow.com/questions/36715803/scrolling-past-the-end-in-idea
// IntelliJ IDEA: Settings -> Editor -> General -> Check Show virtual space at file bottom
JTextArea textArea = new JTextArea() {
  // https://stackoverflow.com/questions/32679335/java-jtextarea-allow-scrolling-beyond-end-of-text
  @Override public Dimension getPreferredSize() {
    Dimension d = super.getPreferredSize();
    Container c = SwingUtilities.getAncestorOfClass(JScrollPane.class, this);
    if (c instanceof JScrollPane && isEditable()) {
      Rectangle r = ((JScrollPane) c).getViewportBorderBounds();
      d.height += r.height - getRowHeight() - getInsets().bottom;
    }
    return d;
  }
};

References

• swing - Java JTextArea allow scrolling beyond end of text - Stack Overflow
• Scrolling past the end in IDEA - Stack Overflow
• Make the editable JTextArea scrollable beyond its last line(Japanese)

Use AffineTransform to place Roman numerals on an analog clock face

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

Code

private final String[] arabicNumerals = {
  "12", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11"
};
private final String[] romanNumerals = {
  "XII", "I", "II", "III", "IIII", "V", "VI", "VII", "VIII", "IX", "X", "XI"
};

private void paintClockNumbers(
    Graphics2D g2, double radius, double hourMarkerLen) {
  AffineTransform at = AffineTransform.getRotateInstance(0d);
  g2.setColor(Color.WHITE);
  Font font = g2.getFont();
  FontRenderContext frc = g2.getFontRenderContext();
  if (isRomanNumerals) {
    AffineTransform si = AffineTransform.getScaleInstance(1d, 2d);
    for (String txt : romanNumerals) {
      Shape s = getTextLayout(txt, font, frc).getOutline(si);
      Rectangle2D r = s.getBounds2D();
      double tx = r.getCenterX();
      double ty = radius - hourMarkerLen - r.getHeight() + r.getCenterY() * .5;
      Shape t = AffineTransform.getTranslateInstance(-tx, -ty)
                               .createTransformedShape(s);
      g2.fill(at.createTransformedShape(t));
      at.rotate(Math.PI / 6d);
    }
  } else {
    Point2D ptSrc = new Point2D.Double();
    for (String txt : arabicNumerals) {
      Shape s = getTextLayout(txt, font, frc).getOutline(null);
      Rectangle2D r = s.getBounds2D();
      double ty = radius - hourMarkerLen - r.getHeight() - r.getCenterY() * .5;
      ptSrc.setLocation(0d, -ty);
      Point2D pt = at.transform(ptSrc, null);
      double dx = pt.getX() - r.getCenterX();
      double dy = pt.getY() - r.getCenterY();
      // g2.drawString(txt, (float) dx, (float) dy);
      g2.fill(AffineTransform.getTranslateInstance(dx, dy)
        .createTransformedShape(s));
      at.rotate(Math.PI / 6d);
    }
  }
}

private static TextLayout getTextLayout(
    String txt, Font font, FontRenderContext frc) {
  return new TextLayout(txt, font, frc);
}

References

• Use AffineTransform to place Roman numerals on an analog clock face(Japanese)
• Java Swing Tips: Drawing Analog Clock Hands in JPanel using Timer

use a newspaper-style JList that can scroll and display multiple items as a ComboBoxEditor

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

Code

ListModel<ListItem> model = makeModel();
JList<ListItem> list = new NewspaperStyleList<>(model);
JScrollPane scroll = new JScrollPane(list) {
  @Override public Dimension getPreferredSize() {
    Dimension d = super.getPreferredSize();
    d.width = 62 * 3 + 10;
    d.height = 32;
    return d;
  }
};
scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER);
scroll.setBorder(BorderFactory.createEmptyBorder());
scroll.setViewportBorder(BorderFactory.createEmptyBorder());

JList<ListItem> list2 = new NewspaperStyleList<>(model);
JScrollPane scroll2 = new JScrollPane(list2) {
  @Override public Dimension getPreferredSize() {
    Dimension d = super.getPreferredSize();
    d.width = 62 * 4 + 10;
    return d;
  }
};
scroll2.setBorder(BorderFactory.createEmptyBorder());
scroll2.setViewportBorder(BorderFactory.createEmptyBorder());

JPopupMenu popup = new JPopupMenu();
popup.setLayout(new BorderLayout());
list2.addMouseListener(new MouseAdapter() {
  @Override public void mouseClicked(MouseEvent e) {
    if (popup.isVisible() && e.getClickCount() >= 2) {
      popup.setVisible(false);
    }
  }
});
popup.add(scroll2);
popup.setBorder(BorderFactory.createLineBorder(Color.GRAY));

JToggleButton dropDown = new JToggleButton(new DropDownArrowIcon());
popup.addPopupMenuListener(new PopupMenuListener() {
  @Override public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
    list2.setSelectedIndex(list.getSelectedIndex());
    EventQueue.invokeLater(popup::pack);
  }

  @Override public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
    dropDown.setSelected(false);
    list.requestFocusInWindow();
    int i = list2.getSelectedIndex();
    if (i >= 0) {
      list.setSelectedIndex(i);
      list.scrollRectToVisible(list.getCellBounds(i, i));
    }
  }

  @Override public void popupMenuCanceled(PopupMenuEvent e) {
    popupMenuWillBecomeInvisible(e);
  }
});

dropDown.setBorder(BorderFactory.createEmptyBorder());
dropDown.setContentAreaFilled(false);
dropDown.setFocusPainted(false);
dropDown.setFocusable(false);
dropDown.addItemListener(e -> {
  AbstractButton b = (AbstractButton) e.getItemSelectable();
  if (e.getStateChange() == ItemEvent.SELECTED) {
    popup.show(b, -scroll.getWidth(), b.getHeight());
  }
});

JScrollBar verticalScrollBar = scroll.getVerticalScrollBar();
JPanel verticalBox = new JPanel(new BorderLayout()) {
  @Override public Dimension getPreferredSize() {
    Dimension d = super.getPreferredSize();
    d.height = 32 + 5 + 5;
    return d;
  }
};
verticalBox.setOpaque(false);
verticalBox.add(verticalScrollBar);
verticalBox.add(dropDown, BorderLayout.SOUTH);

JPanel panel = new JPanel(new BorderLayout(0, 0));
panel.add(scroll);
panel.add(verticalBox, BorderLayout.EAST);
panel.setBorder(BorderFactory.createLineBorder(Color.DARK_GRAY));

References

• use a newspaper-style JList that can scroll and display multiple items as a ComboBoxEditor(Japanese)

Change the height of a drop-down list of JComboBox by mouse dragging

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

Code

JPopupMenu popup = new JPopupMenu();
popup.setBorder(BorderFactory.createEmptyBorder());
popup.setPopupSize(240, 120);

JLabel bottom = new JLabel("", new DotIcon(), SwingConstants.CENTER);
MouseInputListener rwl = new ResizeWindowListener(popup);
bottom.addMouseListener(rwl);
bottom.addMouseMotionListener(rwl);
bottom.setCursor(Cursor.getPredefinedCursor(Cursor.S_RESIZE_CURSOR));
bottom.setOpaque(true);
bottom.setBackground(new Color(0xE0_E0_E0));
bottom.setFocusable(false);

JPanel resizePanel = new JPanel(new BorderLayout());
resizePanel.add(scroll);
resizePanel.add(bottom, BorderLayout.SOUTH);
resizePanel.add(Box.createHorizontalStrut(240), BorderLayout.NORTH);
resizePanel.setBorder(BorderFactory.createLineBorder(new Color(0x64_64_64)));

JPopupMenu popup = new JPopupMenu();
popup.add(resizePanel);

// ...
class ResizeWindowListener extends MouseInputAdapter {
  private final Rectangle rect = new Rectangle();
  private final JPopupMenu popup;
  private final Point startPt = new Point();
  private final Dimension startDim = new Dimension();

  protected ResizeWindowListener(JPopupMenu popup) {
    this.popup = popup;
  }

  @Override public void mousePressed(MouseEvent e) {
    rect.setSize(popup.getSize());
    startDim.setSize(popup.getSize());
    startPt.setLocation(e.getComponent().getLocationOnScreen());
  }

  @Override public void mouseDragged(MouseEvent e) {
    rect.height = startDim.height + e.getLocationOnScreen().y - startPt.y;
    popup.setPreferredSize(rect.getSize());
    Window w = SwingUtilities.getWindowAncestor(popup);
    if (w != null && w.getType() == Window.Type.POPUP) {
      // Popup$HeavyWeightWindow
      w.setSize(rect.width, rect.height);
    } else {
      // Popup$LightWeightWindow
      popup.pack();
    }
  }
}

References

• Change the height of a drop-down list of JComboBox by mouse dragging(Japanese)