source: src/main/java/genius/gui/panels/ComboboxSelectionPanel.java@ 61

package genius.gui.panels;

import java.awt.BorderLayout;
import java.awt.Dimension;

import javax.swing.DefaultListCellRenderer;
import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.ListCellRenderer;
import javax.swing.event.ListDataEvent;
import javax.swing.event.ListDataListener;

/**
 * A GUI that shows panel with given title at the left and a combobox at the
 * right. In the combo, the user can select an item from a list. This panel
 * hides automatically if there are no selectable items.
 * 
 * The text label is set fixed to 120 pixels to get some nice column layout
 *
 * @param <ItemType>
 *            the type of the elements in the item list.
 */
@SuppressWarnings("serial")
public class ComboboxSelectionPanel<ItemType> extends JPanel {

        private SingleSelectionModel<ItemType> model;
        final JComboBox<ItemType> combo;

        /**
         * 
         * @param title
         *            the text to be placed left of the combo box
         * @param itemsModel
         *            the {@link SingleSelectionModel} that contains the possible
         *            choices and can be listened for changes.
         */
        public ComboboxSelectionPanel(final String title,
                        final SingleSelectionModel<ItemType> itemsModel) {
                this.model = itemsModel;
                setLayout(new BorderLayout());
                combo = new JComboBox<ItemType>(itemsModel);

                JLabel label = new JLabel(title);
                // sets a FIXED (not preferred?) size for these.
                label.setPreferredSize(new Dimension(120, 10));
                add(label, BorderLayout.WEST);
                add(combo, BorderLayout.CENTER);
                updateVisibility();

                itemsModel.addListDataListener(new ListDataListener() {

                        @Override
                        public void intervalRemoved(ListDataEvent e) {
                                updateVisibility();
                        }

                        @Override
                        public void intervalAdded(ListDataEvent e) {
                                updateVisibility();
                        }

                        @Override
                        public void contentsChanged(ListDataEvent e) {
                                updateVisibility();
                        }

                });
        }

        /**
         * We are visible only if there is at least one possible selection. This
         * enables us to hide eg the Mediator combobox by just emptying the mediator
         * list in the model.
         */
        private void updateVisibility() {
                // FIXME invokelater
                setVisible(model.getSize() > 0);
        }

        /**
         * Set the cell renderer.
         * 
         * @param renderer
         *            a {@link DefaultListCellRenderer}. Note, for unknown reason,
         *            {@link DefaultListCellRenderer} implements
         *            {@link ListCellRenderer}&lt;object&gt; and ignores the proper
         *            typing
         */
        public void setCellRenderer(DefaultListCellRenderer renderer) {
                combo.setRenderer(renderer);
        }

}