Align a JLabel with the text of a JCheckBox

Is there a look-and-feel-independent way to align a component (e.g. a JLabel) horizontally with the text of a JCheckBox?

I am trying to use values from the UIDefaults to predict the location of the text relative to the top-left corner of the JCheckBox. I have found a combination that gives the right result for the Metal, Windows, Motif and Aqua Look-and-Feels:
Example: Metal (correctly-aligned)

But not in Nimbus:
Example: Nimbus (incorrectly-aligned)

Is there a utility method somewhere that will reliably give X,Y offsets for the text in all Look-and-Feels?

Code (note: to avoid any layout side-effects I used a null layout for this test):

import java.awt.Insets;

import javax.swing.JApplet;
import javax.swing.JCheckBox;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.border.Border;

public class AlignCheckBoxText extends JApplet {

    public AlignCheckBoxText() {
        setLayout(null);
        checkBox = new JCheckBox("Hello, World!");
        label = new JLabel("Hello, World!");
        add(checkBox);
        add(label);
    }

    @Override
    protected void validateTree() {
        checkBox.setLocation(0, 0);
        checkBox.setSize(checkBox.getPreferredSize());
        int labelX = UIManager.getIcon("CheckBox.icon").getIconWidth();
        Insets cbInsets = UIManager.getInsets("CheckBox.margin");
        if (cbInsets != null) labelX += cbInsets.left + cbInsets.right;
        Border cbBorder = UIManager.getBorder("CheckBox.border");
        if (cbBorder != null) {
            Insets borderInsets = cbBorder.getBorderInsets(checkBox);
            if (borderInsets != null) {
                labelX += borderInsets.left; 
            }
        }
        label.setLocation(labelX, checkBox.getHeight());
        label

You can right-align the label and set its width to be checkbox's width minus right border. It works for all LAFs with Windows JDK1.6.0_21, including Nimbus. I don't have a Mac so can't test Aqua.

Here's your code very slightly modified:

class AlignCheckBoxText extends JApplet {

    public AlignCheckBoxText() {
        setLayout(null);
        checkBox = new JCheckBox("Hello, World!");
        label = new JLabel("Hello, World!");
        add(checkBox);
        add(label);        
        label.setHorizontalAlignment(JLabel.TRAILING);
    }

    @Override
    protected void validateTree() {
        checkBox.setLocation(0, 0);
        checkBox.setSize(checkBox.getPreferredSize());
        int x = 0;
        Border cbBorder = UIManager.getBorder("CheckBox.border");
        if (cbBorder != null) {
            Insets borderInsets = cbBorder.getBorderInsets(checkBox);
            if (borderInsets != null) {
                x += borderInsets.right;
            }
        }
        label.setLocation(0, checkBox.getHeight());
        label.setSize(new Dimension(checkBox.getPreferredSize().width - x, label.getPreferredSize().height));
        super.validateTree();
    }

    private JCheckBox checkBox;
    private JLabel label;

}

answered 2010-09-18T21:49:50.067

Align a JLabel with the text of a JCheckBox

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