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2018/12/27

aterai

Fade out JTabbedPane tab title on overflow instead of ellipsis

Code

class TextOverflowFadeTabbedPane extends ClippedTitleTabbedPane {
  protected TextOverflowFadeTabbedPane() {
    super();
  }

  protected TextOverflowFadeTabbedPane(int tabPlacement) {
    super(tabPlacement);
  }

  @Override public void insertTab(
        String title, Icon icon, Component component, String tip, int index) {
    super.insertTab(title, icon, component, Objects.toString(tip, title), index);
    JPanel p = new JPanel(new BorderLayout(2, 0));
    p.setOpaque(false);
    p.add(new JLabel(icon), BorderLayout.WEST);
    p.add(new TextOverflowFadeLabel(title));
    setTabComponentAt(index, p);
  }
}

class TextOverflowFadeLabel extends JLabel {
  private static final int LENGTH = 20;
  private static final float DIFF = .05f;

  protected TextOverflowFadeLabel(String text) {
    super(text);
  }

  @Override public void paintComponent(Graphics g) {
    Insets i = getInsets();
    int w = getWidth() - i.left - i.right;
    int h = getHeight() - i.top - i.bottom;
    Rectangle rect = new Rectangle(i.left, i.top, w - LENGTH, h);

    Graphics2D g2 = (Graphics2D) g.create();
    g2.setFont(g.getFont());
    g2.setPaint(getForeground());

    FontRenderContext frc = g2.getFontRenderContext();
    TextLayout tl = new TextLayout(getText(), getFont(), frc);
    int baseline = getBaseline(w, h);

    g2.setClip(rect);
    tl.draw(g2, getInsets().left, baseline);

    rect.width = 1;
    float alpha = 1f;
    for (int x = w - LENGTH; x < w; x++) {
      rect.x = x;
      alpha = Math.max(0f, alpha - DIFF);
      g2.setComposite(AlphaComposite.SrcOver.derive(alpha));
      g2.setClip(rect);
      tl.draw(g2, getInsets().left, baseline);
    }
    g2.dispose();
  }
}

References

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