// This example is from the book "Java in a Nutshell, Second Edition".
// Written by David Flanagan.  Copyright (c) 1997 O'Reilly & Associates.
// You may distribute this source code for non-commercial purposes only.
// You may study, modify, and use this example for any purpose, as long as
// this notice is retained.  Note that this example is provided "as is",
// WITHOUT WARRANTY of any kind either expressed or implied.

import java.awt.*;               // ScrollPane, PopupMenu, MenuShortcut, etc.
import java.awt.datatransfer.*;  // Clipboard, Transferable, DataFlavor, etc.
import java.awt.event.*;         // New event model.
import java.io.*;                // Object serialization streams.
import java.util.zip.*;          // Data compression/decompression streams.
import java.util.Vector;         // To store the scribble in.
import java.util.Properties;     // To store printing preferences in.

/**
 * This class places a Scribble component in a ScrollPane container,
 * puts the ScrollPane in a window, and adds a simple pulldown menu system.
 * The menu uses menu shortcuts.  Events are handled with anonymous classes.
 */
public class ScribbleFrame extends Frame {
  /** A very simple main() method for our program. */
  public static void main(String[] args) { new ScribbleFrame(); }

  /** Remember # of open windows so we can quit when last one is closed */
  protected static int num_windows = 0;

  /** Create a Frame, Menu, and ScrollPane for the scribble component */
  public ScribbleFrame() {
    super("ScribbleFrame");                  // Create the window.
    num_windows++;                           // Count it.

    ScrollPane pane = new ScrollPane();      // Create a ScrollPane.
    pane.setSize(300, 300);                  // Specify its size.
    this.add(pane, "Center");                // Add it to the frame.
    Scribble scribble;
    scribble = new Scribble(this, 500, 500); // Create a bigger scribble area.
    pane.add(scribble);                      // Add it to the ScrollPane.

    MenuBar menubar = new MenuBar();         // Create a menubar.
    this.setMenuBar(menubar);                // Add it to the frame.
    Menu file = new Menu("File");            // Create a File menu.
    menubar.add(file);                       // Add to menubar.

    // Create three menu items, with menu shortcuts, and add to the menu.
    MenuItem n, c, q;
    file.add(n = new MenuItem("New Window", new MenuShortcut(KeyEvent.VK_N)));
    file.add(c = new MenuItem("Close Window",new MenuShortcut(KeyEvent.VK_W)));
    file.addSeparator();                     // Put a separator in the menu
    file.add(q = new MenuItem("Quit", new MenuShortcut(KeyEvent.VK_Q)));

    // Create and register action listener objects for the three menu items.
    n.addActionListener(new ActionListener() {     // Open a new window
      public void actionPerformed(ActionEvent e) { new ScribbleFrame(); }
    });
    c.addActionListener(new ActionListener() {     // Close this window.
      public void actionPerformed(ActionEvent e) { close(); }
    });
    q.addActionListener(new ActionListener() {     // Quit the program.
      public void actionPerformed(ActionEvent e) { System.exit(0); }
    });

    // Another event listener, this one to handle window close requests.
    this.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) { close(); }
    });

    // Set the window size and pop it up.
    this.pack();
    this.show();
  }

  /** Close a window.  If this is the last open window, just quit. */
  void close() {
    if (--num_windows == 0) System.exit(0);
    else this.dispose();
  }
}

/**
 * This class is a custom component that supports scribbling.  It also has
 * a popup menu that allows the scribble color to be set and provides access
 * to printing, cut-and-paste, and file loading and saving facilities.
 * Note that it extends Component rather than Canvas, making it "lightweight."
 */
class Scribble extends Component implements ActionListener {
  protected short last_x, last_y;                // Coordinates of last click.
  protected Vector lines = new Vector(256,256);  // Store the scribbles.
  protected Color current_color = Color.black;   // Current drawing color.
  protected int width, height;                   // The preferred size.
  protected PopupMenu popup;                     // The popup menu.
  protected Frame frame;                         // The frame we are within.

  /** This constructor requires a Frame and a desired size */
  public Scribble(Frame frame, int width, int height) {
    this.frame = frame;
    this.width = width;
    this.height = height;

    // We handle scribbling with low-level events, so we must specify
    // which events we are interested in.
    this.enableEvents(AWTEvent.MOUSE_EVENT_MASK);
    this.enableEvents(AWTEvent.MOUSE_MOTION_EVENT_MASK);

    // Create the popup menu using a loop.  Note the separation of menu
    // "action command" string from menu label.  Good for internationalization.
    String[] labels = new String[] {
      "Clear", "Print", "Save", "Load", "Cut", "Copy", "Paste" };
    String[] commands = new String[] {
      "clear", "print", "save", "load", "cut", "copy", "paste" };
    popup = new PopupMenu();                   // Create the menu
    for(int i = 0; i