//
// another example of the Java AWT, showing use of PopupMenu class.
// see class definition and main method for details.
//
// this example is modified from a similar example in chapter 14 of
//      _Exploring Java_ (Niemeyer and Peck).
//
import java.awt.* ;
import java.awt.event.* ;

//
// a PopupMenu object is a CloseableFrame containing two Button
//      objects.  when the user triggers a popup menu (pressing the
//      right mouse button on Unix/X, pressing and releasing the
//      right mouse button on DOS/Windows), a PopupMenu appears that 
//      allows the user to select a new color for the component (one of
//      the Buttons or the Frame) that contains the cursor.  different 
//      menus are provided for the Buttons and the Frame.
//
class PopupMenuExample extends CloseableFrame {

        PopupMenu buttonColorMenu ;
        PopupMenu frameColorMenu ;
        Component selectedC ;

        PopupMenuExample() {

                super("PopupMenuExample") ;
                setLayout(new FlowLayout()) ;

                add(makeButton("hello")) ;
                add(makeButton("goodbye")) ;

                // listener for selections from one of popup menus.
                ActionListener popupL = new ActionListener() {
                        public void actionPerformed(ActionEvent e) {
                                String s = e.getActionCommand() ;
                                if (s.equals("pink")) 
                                        selectedC.setBackground(
                                                Color.pink) ;
                                else if (s.equals("cyan")) 
                                        selectedC.setBackground(
                                                Color.cyan) ;
                                else if (s.equals("yellow")) 
                                        selectedC.setBackground(
                                                Color.yellow) ;
                                else if (s.equals("white")) 
                                        selectedC.setBackground(
                                                Color.white) ;
                                // force repaint to pick up new
                                //      colors (seems to be necessary
                                //      for some DOS/Windows systems).
                                repaint() ;
                        }
                } ;

                // popup menu for Buttons.
                buttonColorMenu = new PopupMenu("Choose button color") ;
                buttonColorMenu.add(makePMenuItem("pink", popupL)) ;
                buttonColorMenu.add(makePMenuItem("cyan", popupL)) ;
                add(buttonColorMenu) ;

                // popup menu for Frame.
                frameColorMenu = new PopupMenu("Choose frame color") ;
                frameColorMenu.add(makePMenuItem("yellow", popupL)) ;
                frameColorMenu.add(makePMenuItem("white", popupL)) ;
                add(frameColorMenu) ;

                // listener for mouse operations -- processes requests
                //      for popup menus.
                // some systems' popup menus are triggered by 
                //      mouse-press events, some by mouse-release
                //      events, so must check both.
                MouseListener mouseL = new MouseAdapter() {
                        public void mousePressed(MouseEvent e) {
                                checkPopup(e) ;
                        }
                        public void mouseReleased(MouseEvent e) {
                                checkPopup(e) ;
                        }
                } ;
                // add listener to frame and all components it
                //      contains.
                // code in _Exploring Java_ added listener to
                //      Frame only, but this did not work for me,
                //      at least under Unix/X.
                recurseAdd(this, mouseL) ;
                // _EJ_ approach:
                // addMouseListener(mouseL) ;

                pack() ;
                show() ;
        }

        // adds mouse listener to component and its contents.
        void recurseAdd(Component c, MouseListener l) {
                c.addMouseListener(l) ;
                if (c instanceof Container) {
                        Component[] contents =
                                ((Container) c).getComponents() ;
                        for (int i = 0 ; i < contents.length ; i++)
                                recurseAdd(contents[i], l) ;
                }
        }
                
        // checks for popup-menu trigger; if true,
        //      decides which menu to pop up and displays it.
        // this is also modified from the example in _Exploring Java_,
        //      since the method they use also did not work for me.
        void checkPopup(MouseEvent e) {
                if (e.isPopupTrigger()) {
                        // _EJ_ approach:
                        // selectedC = 
                        //      getComponentAt(e.getX(), e.getY()) ;
                        selectedC = (Component) e.getSource() ;
                        if (selectedC instanceof Button)
                                buttonColorMenu.show(e.getComponent(),
                                        e.getX(), e.getY()) ;
                        else if (selectedC instanceof Frame)
                                frameColorMenu.show(e.getComponent(),
                                        e.getX(), e.getY()) ;
                }
        }

        // --- methods to make menu items, buttons ----

        MenuItem makePMenuItem(String label, ActionListener l) {
                MenuItem m = new MenuItem(label) ;
                m.addActionListener(l) ;
                return m ;
        }

        Button makeButton(final String label) {
                Button b = new Button(label) ;
                b.addActionListener(new ActionListener() {
                        public void actionPerformed(ActionEvent e) {
                                System.out.println("button pressed:  " 
                                        + label) ;
                        }
                } ) ;
                return b ;
        }

        //
        // ---- main ---------------------------------------------------
        //
        // no command-line arguments.
        //
        public static void main(String[] args) {

                PopupMenuExample m = new PopupMenuExample() ;
        }
}