import java.awt.*;
import java.applet.Applet;

/**
 <P> This class defines a graphics Frame, initializes the Applet context
   and specifies handling for the WINDOW_DESTROY
   exit event, for a class Room object or for an array of Room objects.
   The class Room implements the graphics window of Feldman's "Spider
   graphics" programs developed in the textbook "Ada 95".

 <P> The AppFrame object in creating a Room, allows proper bootstrapping
   of the Graphics object (context).
   The objects of this class inherit from Frame (they can be drawn into,
   they can be added into a container, resized, shown, and so on).
   When creating a new Frame object, the AppFrame() constructor
   expects an Applet object as its second parameter, and calls the
   Applet.init() method as its last order of business.
   This round-about initialization is necessary for resolving
   a Catch-22 situation, as follows:

 <P>
   The Graphics context of a drawable (surface) is unavailable until the
   drawable is installed in its container.  Prior to this, getGraphics()
   would return null, so it is useless to call it when the drawable is
   instantiated (with "new ...").  By making the drawable an Applet, it
   can be instantiated without calling getGraphics() in the constructor.
   Instead, the init() method of the Applet object (overridden
   in the subclass) is used to call getGraphics().  The AppFrame container
   object can thus install the drawable component, Applet, into its Frame
   first, using the add(), resize() and show() methods of Frame.
   Thereafter the AppFrame() constructor calls the Applet init() method.
   The init() method is overridden in the Room subclass in
   a manner to call getGraphics() and assign the returned value to the
   "Graphics mySurface" field of Room:
  <PRE>
    mySurface  = getGraphics();</PRE>

  <P>
   Other drawable classes could be substituted
   instead of Applet: for example Room could subclass
   Canvas.  Canvas does not have an "init()" method, but a non-overriding
   init() method could be defined in Room nonetheless; or
   a different method name could be used.
   In this case the type of the second parameter of the
   AppFrame constructor would have to be the subclass name Room: the
   parent class Canvas could not be used since it does not have an init()
   method.

@author Michael B. Feldman, The George Washington University (Ada 95)
@author Istvan Mohos (Java translation)
@see Room
@see Spider
*/
class AppFrame extends Frame {

  /** Creates a new Frame titled according to the first parameter,
    resizing it to the width and height passed as the last two parameters,
    and containing the Applet passed as the second parameter.  After
    calling the Frame.show() method, initializes the passed Applet with
    a call to Applet.init().
@param title the String to be displayed in the Frame's title bar.
@param anyApplet the Applet object to be installed in this Frame.
@param wide the desired width of the Frame, in pixels.
@param high the desired height of the Frame, in pixels.
  */
  public AppFrame(String title, Applet anyApplet, int wide, int high) {
    super(title);                          // create the frame
    this.add("Center", anyApplet);         // add applet to frame
    this.resize(wide, high);               // set initial size
    this.show();                           // show frame and component

    Insets insets = insets();
    anyApplet.resize(wide - insets.right - insets.left,
                     high - insets.top - insets.bottom);
    this.show();
    anyApplet.init();                      // initialize the applet
  } // end of AppFrame constructor


  /** Creates a new Frame titled according to the first parameter,
    resizing it to the width and height passed as the last two parameters,
    and containing the array of
    Applets passed as the second parameter.  After
    calling the Frame.show() method, initializes each element of the
    passed Applet array with a call to Applet.init().
@param title the String to be displayed in the Frame's title bar.
@param appletArray the Applet objects to be installed in this Frame.
@param wide the desired width of the Frame, in pixels.
@param high the desired height of the Frame, in pixels.
  */
  public AppFrame(String title, Applet[] appletArray, int wide, int high) {
    super(title);                          // create the frame
    this.resize(wide, high);               // set initial frame size
    this.show();                           // won't have insets before this

    Insets insets = insets();
    int appWide = (wide - insets.right - insets.left -
                   13 * appletArray.length)
                  / appletArray.length;
    int appHigh = high - insets.top - insets.bottom - 2;
    setLayout(new FlowLayout(FlowLayout.RIGHT, appWide, 0));

    for (int i = 0; i < appletArray.length; i++)
      add("Center", appletArray[i]);
    this.show();                           // this time to show the applets

    // Initialize and resize the applets
    for (int i = 0; i < appletArray.length; i++) {
      appletArray[i].resize(appWide, appHigh);
      appletArray[i].init();
    }

  } // end of AppFrame constructor


  /** Overrides java.awt.Component.handleEvent() to be able to exit
    the application on a mouse click over the "X" button in the top
    right corner of the graphics window.  Handles only the WINDOW_DESTROY
    event, by calling System.exit().  All other events are deferred to
    the Component superclass.
@param anyEvent an Event ID delivered to this object.
@return System.exit() does not return.  In all other cases, the boolean
    value returned by the event handler of the superclass,
    Component.handleEvent(), is returned to the caller.
@see java.awt.Component.handleEvent
@see java.lang.System.exit
  */
  public boolean handleEvent(Event anyEvent) {
    if (anyEvent.id == Event.WINDOW_DESTROY)
      System.exit(0);
    return super.handleEvent(anyEvent);
  }

} // end definition of class AppFrame