JMultiSelectionBox.java

package com.vgi.mafscaling;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowFocusListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.AbstractAction;
import javax.swing.BoxLayout;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JComboBox;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingConstants;
import javax.swing.UIDefaults;
import javax.swing.UIManager;
import javax.swing.border.LineBorder;

public class JMultiSelectionBox extends JButton {
    private static final long serialVersionUID = -6780160237517176970L;
    private static int widthCorrection = 2;
    private static int heighCorrection = 2;
    JComboBox<String> combo = new JComboBox<String>();
    JPanel menu = new JPanel();
    JDialog menuFrame = null;
    JScrollPane scroll = null;
    WindowFocusListener windowFocusListener = null;
    MouseListener mouseListener = null;
    ActionListener menuActionListener = null;
    JButton button;
    boolean mouseOver = false;
    
    public JMultiSelectionBox() {
        this(null, null);
    }

    public JMultiSelectionBox(Icon icon) {
        this(null, icon);
    }

    public JMultiSelectionBox(String text) {
        this(text, null);
    }

    public JMultiSelectionBox(String text, Icon icon) {
        super(text, icon);
        if (UIManager.getLookAndFeel().getClass().getName().contains("Motif"))
            heighCorrection += 4;
        windowFocusListener = new WindowFocusListener() {
            @Override
            public void windowGainedFocus(WindowEvent arg0) { }
            @Override
            public void windowLostFocus(WindowEvent arg0) {
                button.setText(getSelectedItemsString());
                if (!mouseOver) {
                    menuFrame.dispose();
                    menuFrame = null;
                }
            }
        };
        mouseListener = new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent e) { }
            @Override
            public void mousePressed(MouseEvent e) { }
            @Override
            public void mouseReleased(MouseEvent e) { }
            @Override
            public void mouseEntered(MouseEvent e) { mouseOver = true; }
            @Override
            public void mouseExited(MouseEvent e) { mouseOver = false; }            
        };
        button = this;
        button.addMouseListener(mouseListener);
        menu.setBackground(Color.WHITE);
        menu.setLayout(new BoxLayout(menu, BoxLayout.Y_AXIS));

        setAction(new AbstractAction(text) {
            private static final long serialVersionUID = -3085698135352698778L;
            @Override
            public void actionPerformed(ActionEvent e) {
                if (menuFrame != null) {
                    menuFrame.dispose();
                    menuFrame = null;
                    return;
                }
                if (menu.getComponentCount() == 0)
                    return;
                menuFrame = new JDialog();
                menuFrame.addWindowFocusListener(windowFocusListener);
                scroll = new JScrollPane(menu);
                scroll.setBorder(new LineBorder(Color.BLACK, 1));
                scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
                scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
                menuFrame.getContentPane().add(scroll);
                menuFrame.setUndecorated(true);
                menuFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                menuFrame.setResizable(false);
                Point location = button.getLocationOnScreen();
                location.y += button.getHeight();
                menuFrame.setLocation(location);
                menuFrame.setPreferredSize(new Dimension(button.getWidth(), 150));
                menuFrame.pack();
                menuFrame.setVisible(true);
                menuFrame.setResizable(false);
                menuFrame.requestFocus();
            }
        });
        menuActionListener = new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                button.setText(getSelectedItemsString());
            }
        };
        setMargin(new Insets(0, 2, 0, 2));
        UIDefaults def = new UIDefaults();
        def.put("Button.contentMargins", new Insets(0, 3, 0, 3));
        putClientProperty("Nimbus.Overrides", def);
        
        setIcon(new ImageIcon(getClass().getResource("/down.gif")));
        setIconTextGap(3);
        
        setVerticalTextPosition(SwingConstants.CENTER);
        setHorizontalAlignment(SwingConstants.RIGHT);
        setHorizontalTextPosition(SwingConstants.LEFT);
    }
    
    public void addItem(String item) {
        JCheckBoxMenuItem menuItem = new JCheckBoxMenuItem(item);
        menuItem.addActionListener(menuActionListener);
        menuItem.setOpaque(false);
        menu.add(menuItem);
    }
    
    public void removeItem(String item) {
        for (int i = 0; i < menu.getComponentCount(); ++i) {
            JCheckBoxMenuItem menuItem = (JCheckBoxMenuItem) menu.getComponent(i);
            if (menuItem.getText().equals(item)) {
                menu.remove(i);
                break;
            }
        }
    }
    
    public void removeAllItems() {
        menu.removeAll();
    }
    
    public List<String> getSelectedItems() {
        ArrayList<String> list = new ArrayList<String>();
        for (int i = 0; i < menu.getComponentCount(); ++i) {
            JCheckBoxMenuItem menuItem = (JCheckBoxMenuItem) menu.getComponent(i);
            if (menuItem.isSelected())
                list.add(menuItem.getText());
        }
        if (list.size() > 0)
            return list;
        return null;
    }
    
    public void setSelectedItems(List<String> items) {
        if (items == null)
            return;
        for (int i = 0; i < menu.getComponentCount(); ++i) {
            JCheckBoxMenuItem menuItem = (JCheckBoxMenuItem) menu.getComponent(i);
            for (String item : items) {
                if (menuItem.getText().equals(item))
                    menuItem.setSelected(true);
            }
        }
        button.setText(getSelectedItemsString());
    }
    
    public String getSelectedItemsString() {
        String s = " ";
        for (int i = 0; i < menu.getComponentCount(); ++i) {
            JCheckBoxMenuItem menuItem = (JCheckBoxMenuItem) menu.getComponent(i);
            if (menuItem.isSelected()) {
                if (s.trim().isEmpty())
                    s += menuItem.getText();
                else
                    s += (" + " + menuItem.getText());
            }
        }
        return s;
    }    

    public void setPrototypeDisplayValue(String val) {
        combo.setPrototypeDisplayValue(val);
    }
    
    @Override
    public Dimension getPreferredSize() {
        Dimension d = combo.getPreferredSize();
        d.width += widthCorrection;
        d.height += heighCorrection;
        return d;
    }
    
    @Override
    public Dimension getMinimumSize() {
        Dimension d = combo.getMinimumSize();
        d.width += widthCorrection;
        d.height += heighCorrection;
        return d;
    }
    
    @Override
    public Dimension getMaximumSize() {
        Dimension d = combo.getMaximumSize();
        d.width += widthCorrection;
        d.height += heighCorrection;
        return d;
    }
}