org.jcsp.awt
Class ActiveClosingFrame

java.lang.Object
  org.jcsp.awt.ActiveClosingFrame

All Implemented Interfaces:

CSProcess

public class ActiveClosingFrame
extends Object
implements CSProcess

A specialisation of ActiveFrame that forces a System.exit upon a Window Closing event.

Process Diagram

Description

ActiveClosingFrame is a process containing an ActiveFrame, configured with channels for event notification and configuration. The event channels should be connected to one or more application-specific server processes (instead of registering a passive object as a Listener to this component).

All channels are optional. The configure and event channels are settable from a constructor.

The difference between this class and ActiveFrame is that a Window Closing event, generated on the (internal) ActiveFrame, is intercepted by the anonymous process and results in a System.exit. This happens regardless as to whether the (external) event channel is null. Otherwise, WindowEvents are forwarded to the (external) event channel, so long as it's not null).

The internal ActiveFrame can be extracted with the getActiveFrame method. Channels can then be added to notify the occurrence of any other type of Event the ActiveFrame generates. This is done by calling its appropriate addXXXEventChannel method (before the process is run). As many channels can be added as are needed.

Messages can be sent down the configure channel at any time to configure the component. See the table below for details.

All channels are managed by independent internal handler processes. It is, therefore, safe for a serial application process both to service an event channel and configure the component -- no deadlock can occur.

IMPORTANT: it is essential that the output channels from this process are always serviced -- otherwise the Java Event Thread will be blocked and the GUI will stop responding. The simplest way to guarantee this is to use channels configured with overwriting buffers. For example:

   final One2OneChannel myWindowEvent = Channel.one2one (new OverWriteOldestBuffer (n));
   final One2OneChannel myMouseEvent = Channel.one2one (new OverWriteOldestBuffer (n));
 
   final ActiveClosingFrame myFrame = new ActiveClosingFrame (myWindowEvent.out ());
   final ActiveFrame myActiveFrame = myFrame.getActiveFrame ();
   myActiveFrame.addMouseEventChannel (myMouseEvent.out ());
 

This will ensure that the Java Event Thread will never be blocked. Slow or inattentive readers may miss rapidly generated events, but the n most recent events will always be available.

Channel Protocols

Input Channels
configure	Boolean	If this is the Boolean.TRUE object, the frame is made visible If this is the Boolean.FALSE object, the frame is made invisible Other Boolean objects are ignored
	ActiveFrame.Configure	Invoke the user-defined Configure.configure method on the frame.
Output Channels
event	WindowEvent	The WindowEvent generated by the component (note that Window Closing is handled locally to cause a System.exit).
containerEvent	ContainerEvent	See the getActiveFrame.addContainerEventChannel method.
componentEvent	ComponentEvent	See the getActiveFrame.addComponentEventChannel method.
focusEvent	FocusEvent	See the getActiveFrame.addFocusEventChannel method.
keyEvent	KeyEvent	See the getActiveFrame.addKeyEventChannel method.
mouseEvent	MouseEvent	See the getActiveFrame.addMouseEventChannel method.
mouseMotionEvent	MouseEvent	See the getActiveFrame.addMouseMotionEventChannel method.

Example

 import java.awt.*;
 import java.awt.event.*;
 import org.jcsp.lang.*;
 import org.jcsp.util.*;
 import org.jcsp.awt.*;
 
 public class ActiveClosingFrameButtonExample {
 
   public static void main (String argv[]) {
 
     final ActiveClosingFrame frame =
       new ActiveClosingFrame ("ActiveClosingFrameButton Example");
 
     final String[] label = {"Hello World", "Rocket Science", "CSP",
                             "Monitors", "Ignore Me", "Goodbye World"};
 
     final Any2OneChannel buttonEvent = Channel.any2one (new OverWriteOldestBuffer (10));
 
     final ActiveButton[] button = new ActiveButton[label.length];
     for (int i = 0; i < label.length; i++) {
       button[i] = new ActiveButton (null, buttonEvent.out (), label[i]);
     }
 
     final Frame realFrame = frame.getActiveFrame ();
     realFrame.setSize (300, 200);
     realFrame.setLayout (new GridLayout (label.length/2, 2));
     for (int i = 0; i < label.length; i++) {
       realFrame.add (button[i]);
     }
     realFrame.setVisible (true);
 
     new Parallel (
       new CSProcess[] {
         frame,
         new Parallel (button),
         new CSProcess () {
           public void run () {
             boolean running = true;
             while (running) {
               final String s = (String) buttonEvent.in ().read ();
               System.out.println ("Button `" + s + "' pressed ...");
               running = (s != label[label.length - 1]);
             }
             realFrame.setVisible (false);
             System.exit (0);
           }
         }
       }
     ).run ();
 
   }
 
 }
 

Author:

P.D. Austin and P.H. Welch

See Also:

ActiveFrame, Frame, ContainerEvent, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer

Constructor Summary

ActiveClosingFrame()
Constructs a new ActiveClosingFrame with no title and no configuration or event channels.

ActiveClosingFrame(ChannelInput configure, ChannelOutput event)
Constructs a new ActiveClosingFrame with configuration and event channels, but no title.

ActiveClosingFrame(ChannelInput configure, ChannelOutput event, String title)
Constructs a new ActiveClosingFrame with configuration and event channels and a title.

ActiveClosingFrame(String title)
Constructs a new ActiveClosingFrame with a title but no configuration or event channels.

Method Summary

ActiveFrame	getActiveFrame() This is used to get the ActiveFrame within this component so that it can be configured or have components added (using Frame or ActiveFrame methods).
void	run() The main body of this process.
void	setConfigureChannel(ChannelInput configure) Sets the configuration channel for this ActiveButton.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ActiveClosingFrame

public ActiveClosingFrame()

Constructs a new ActiveClosingFrame with no title and no configuration or event channels.

ActiveClosingFrame

public ActiveClosingFrame(String title)

Constructs a new ActiveClosingFrame with a title but no configuration or event channels.

Parameters:

title - the title for the frame.

ActiveClosingFrame

public ActiveClosingFrame(ChannelInput configure,
                          ChannelOutput event)

Constructs a new ActiveClosingFrame with configuration and event channels, but no title.

Parameters:

configure - the channel for configuration events -- can be null if no configuration is required.

event - a WindowEvent will be output whenever it occurs -- can be null if no notification is required.

ActiveClosingFrame

public ActiveClosingFrame(ChannelInput configure,
                          ChannelOutput event,
                          String title)

Constructs a new ActiveClosingFrame with configuration and event channels and a title.

Parameters:

configure - the channel for configuration events -- can be null if no configuration is required.

event - a WindowEvent will be output whenever it occurs -- can be null if no notification is required.

title - the title for the frame.

Method Detail

setConfigureChannel

public void setConfigureChannel(ChannelInput configure)

Sets the configuration channel for this ActiveButton. This method overwrites any configuration channel set in the constructor.

Parameters:

configure - the channel for configuration events -- can be null if no configuration is required.

getActiveFrame

public ActiveFrame getActiveFrame()

This is used to get the ActiveFrame within this component so that it can be configured or have components added (using Frame or ActiveFrame methods). For example, event channels can be added by invoking getActiveFrame().addXXXEventChannel(...).

NOTE: This must be finished before this process is run.

Returns:

the Frame within this component.

run

public void run()

The main body of this process.

Specified by:

run in interface CSProcess