Swing Menus and Toolbars - The Definitive Guide to Java Swing - page 183

Table 6-12. JCheckBoxMenuItem UIResource Elements (Continued)

Property String Object Type

CheckBoxMenuItem.checkIcon Icon

CheckBoxMenuItem.commandSound String

CheckBoxMenuItem.disabledForeground Color

CheckBoxMenuItem.font Font

CheckBoxMenuItem.foreground Color

CheckBoxMenuItem.gradient List

CheckBoxMenuItem.margin Insets

CheckBoxMenuItem.opaque Boolean

CheckBoxMenuItem.selectionBackground Color

CheckBoxMenuItem.selectionForeground Color

CheckBoxMenuItemUI String

The Icon associated with the CheckBoxMenuItem.checkIcon property key is the one displayed on
the JCheckBoxMenuItem . If you don't like the default icon, you can change it with the following line
of source, assuming the new icon has already been defined and created:

UIManager.put("CheckBoxMenuItem.checkIcon", someIcon);

For this new icon to display an appropriate selected image, the Icon implementation
must check the state of the associated menu component within its paintIcon() method. The
DiamondIcon created in Chapter 4 wouldn't work for this icon because it doesn't ask the compo-
nent for its state. Instead, the state is fixed at constructor time. Listing 6-4 shows a class that
represents one icon that could be used.

Listing 6-4. State-Aware Icon Definition

import java.awt.*;
import javax.swing.*;

public class DiamondAbstractButtonStateIcon implements Icon {
private final int width = 10;
private final int height = 10;
private Color color;
private Polygon polygon;
public DiamondAbstractButtonStateIcon(Color color) {
this.color = color;
initPolygon();
}