Left Clipped JComboBox

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

Code

final JButton arrowButton = getArrowButton(combo02);
combo02.setRenderer(new DefaultListCellRenderer() {
  public Component getListCellRendererComponent(JList list, Object value, int index,
                          boolean isSelected, boolean cellHasFocus) {
    super.getListCellRendererComponent(list,value,index,isSelected,cellHasFocus);
    int itb=0, ilr=0;
    Insets insets = getInsets();
    itb+=insets.top+insets.bottom; ilr+=insets.left+insets.right;
    insets = combo02.getInsets();
    itb+=insets.top+insets.bottom; ilr+=insets.left+insets.right;
    int availableWidth = combo02.getWidth()-ilr;
    if(index < 0) {
      //@see BasicComboBoxUI#rectangleForCurrentValue
      int buttonSize = combo02.getHeight()-itb;
      if(arrowButton!=null) {
        buttonSize = arrowButton.getWidth();
      }
      availableWidth -= buttonSize;
      JTextField tf = (JTextField)combo02.getEditor().getEditorComponent();
      insets = tf.getMargin();
      availableWidth -= (insets.left + insets.right);
    }
    String cellText = (value!=null)?value.toString():"";
    //blockquote
    //@cite http://tips4java.wordpress.com/2008/11/12/left-dot-renderer/
    //@title Left Dot Renderer
    //@auther Rob Camick
    //FontMetrics fm = getFontMetrics(getFont());
    //if(fm.stringWidth(cellText) > availableWidth) {
    //  String dots = "...";
    //  int textWidth = fm.stringWidth(dots);
    //  int nChars = cellText.length() - 1;
    //  while(nChars > 0) {
    //    textWidth += fm.charWidth(cellText.charAt(nChars));
    //    if(textWidth > availableWidth) break;
    //    nChars--;
    //  }
    //  setText(dots+cellText.substring(nChars+1));
    //}
    //blockquote

    // Unicode surrogate programming with the Java language
    // http://www.ibm.com/developerworks/library/j-unicode/index.html
    FontMetrics fm = getFontMetrics(getFont());
    if (fm.stringWidth(cellText) > availableWidth) {
      String dots = "...";
      int textWidth = fm.stringWidth(dots);
      int len = cellText.length();
      int[] acp = new int[cellText.codePointCount(0, len)];
      int j = acp.length;
      for (int i = len; i > 0; i = cellText.offsetByCodePoints(i, -1)) {
        int cp = cellText.codePointBefore(i);
        textWidth += fm.charWidth(cp);
        if (textWidth > availableWidth) {
          break;
        }
        acp[--j] = cp;
      }
      setText(dots + new String(acp, j, acp.length - j));
    }
    return this;
  }
});

References

• Left Dot Renderer ≪ Java Tips Weblog
• Left Clipped JComboBox(Japanese)