CSP for Java
(JCSP) 1.0-rc4

jcsp.awt
Class ActiveComponent

java.lang.Object
  |
  +--java.awt.Component
        |
        +--jcsp.awt.ActiveComponent
All Implemented Interfaces:
CSProcess, ImageObserver, MenuContainer, Serializable

public class ActiveComponent
extends Component
implements CSProcess

java.awt.Component with a channel interface.

Process Diagram

                              ___________________
                             |                   |
                             |                   | componentEvent
                             |                   |----->-----
                             |                   | (java.awt.event.ComponentEvent)
                             |                   |
                             |                   | focusEvent
                             |                   |----->-----
                             |                   | (java.awt.event.FocusEvent)
                             |                   |
                   configure |                   | keyEvent
                  ----->-----|  ActiveComponent  |----->-----
 (ActiveComponent.Configure) |                   | (java.awt.event.KeyEvent)
                             |                   |
                             |                   | mouseEvent
                             |                   |----->-----
                             |                   | (java.awt.event.MouseEvent)
                             |                   |
                             |                   | mouseMotionEvent
                             |                   |----->-----
                             |                   | (java.awt.event.MouseEvent)
                             |___________________|  
 

Description

ActiveComponent is a process extension of java.awt.Component with channels for run-time configuration and event notification. 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 channel is settable from a constructor. Event channels can be added to notify the occurrence of any type of Event the component generates (by calling the appropriate addXXXEventChannel method before the process is run). 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 event channels from this process are always serviced -- otherwise the Java Event Thread will be blocked and the GUI will stop responding. A simple way to guarantee this is to use channels configured with overwriting buffers. For example:

   final One2OneChannel myMouseEvent =
     One2OneChannel.create (new OverWriteOldestBuffer (n));
 
   final ActiveComponent myComponent = new ActiveComponent ();
   myComponent.addMouseEventChannel (myMouseEvent);
 
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 ActiveComponent.Configure Invoke the user-defined Configure.configure method on the component.
Output Channels
componentEvent ComponentEvent See the addComponentEventChannel method.
focusEvent FocusEvent See the addFocusEventChannel method.
keyEvent KeyEvent See the addKeyEventChannel method.
mouseEvent MouseEvent See the addMouseEventChannel method.
mouseMotionEvent MouseEvent See the addMouseMotionEventChannel method.

Example

 import java.awt.*;
 import java.awt.event.*;
 import jcsp.util.*;
 import jcsp.lang.*;
 import jcsp.awt.*;
 
 public class ActiveComponentExample {
 
   public static void main (String argv[]) {
 
     final Frame root = new Frame ("ActiveComponent Example");
 
     final One2OneChannel mouseEvent =
       One2OneChannel.create (new OverWriteOldestBuffer (10));
 
     final ActiveComponent component = new ActiveComponent ();
     component.addMouseEventChannel (mouseEvent);
 
     root.add (component);
     root.setSize (400, 400);
     root.setVisible (true);
 
     new Parallel (
       new CSProcess[] {
         component,
         new CSProcess () {
           public void run () {
             boolean running = true;
             while (running) {
               switch (((MouseEvent) mouseEvent.read ()).getID ()) {
                 case MouseEvent.MOUSE_ENTERED:
                   System.out.println ("MOUSE_ENTERED");
                 break;
                 case MouseEvent.MOUSE_EXITED:
                   System.out.println ("MOUSE_EXITED");
                 break;
                 case MouseEvent.MOUSE_PRESSED:
                   System.out.println ("MOUSE_PRESSED");
                 break;
                 case MouseEvent.MOUSE_RELEASED:
                   System.out.println ("MOUSE_RELEASED");
                 break;
                 case MouseEvent.MOUSE_CLICKED:
                   System.out.println ("MOUSE_CLICKED ... goodbye!");
                   running = false;
                 break;
               }
             }
             root.setVisible (false);
             System.exit (0);
           }
         }
       }
     ).run ();
   }
 
 }
 

Author:
P.D.Austin and P.H.Welch
See Also:
Component, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer, Serialized Form

Inner Class Summary
static interface ActiveComponent.Configure
          This enables general configuration of this component.
 
Inner classes inherited from class java.awt.Component
Component.AccessibleAWTComponent
 
Fields inherited from class java.awt.Component
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
 
Fields inherited from interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
 
Constructor Summary
ActiveComponent()
          Constructs a new ActiveComponent with no configuration channel.
ActiveComponent(ChannelInput configure)
          Constructs a new ActiveComponent with a configuration channel.
 
Method Summary
 void addComponentEventChannel(ChannelOutput componentEvent)
          Add a new channel to this component that will be used to notify that a ComponentEvent has occurred.
 void addFocusEventChannel(ChannelOutput focusEvent)
          Add a new channel to this component that will be used to notify that a FocusEvent has occurred.
 void addKeyEventChannel(ChannelOutput keyEvent)
          Add a new channel to this component that will be used to notify that a KeyEvent has occurred.
 void addMouseEventChannel(ChannelOutput mouseEvent)
          Add a new channel to this component that will be used to notify that a MouseEvent has occurred.
 void addMouseMotionEventChannel(ChannelOutput mouseMotionEvent)
          Add a new channel to this component that will be used to notify that a MouseMotionEvent has occurred.
 void run()
          The main body of this process.
 void setConfigureChannel(ChannelInput configure)
          Sets the configuration channel for this ActiveComponent.
 
Methods inherited from class java.awt.Component
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addNotify, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAccessibleContext, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getInputContext, getInputMethodRequests, getListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getName, getParent, getPeer, getPreferredSize, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, paramString, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

ActiveComponent

public ActiveComponent()
Constructs a new ActiveComponent with no configuration channel.

ActiveComponent

public ActiveComponent(ChannelInput configure)
Constructs a new ActiveComponent with a configuration channel.
Parameters:
configure - the channel for configuration events -- can be null if no configuration is required.
Method Detail

setConfigureChannel

public void setConfigureChannel(ChannelInput configure)
Sets the configuration channel for this ActiveComponent. 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.

addComponentEventChannel

public void addComponentEventChannel(ChannelOutput componentEvent)
Add a new channel to this component that will be used to notify that a ComponentEvent has occurred. This should be used instead of registering a ComponentListener with the component. It is possible to add more than one Channel by calling this method multiple times If the channel passed is null, no action will be taken.

NOTE: This method must be called before this process is run.

Parameters:
componentEvent - the channel down which ComponentEvents will be sent.

addFocusEventChannel

public void addFocusEventChannel(ChannelOutput focusEvent)
Add a new channel to this component that will be used to notify that a FocusEvent has occurred. This should be used instead of registering a FocusListener with the component. It is possible to add more than one Channel by calling this method multiple times If the channel passed is null, no action will be taken.

NOTE: This method must be called before this process is run.

Parameters:
focusEvent - the channel down which FocusEvents will be sent.

addKeyEventChannel

public void addKeyEventChannel(ChannelOutput keyEvent)
Add a new channel to this component that will be used to notify that a KeyEvent has occurred. This should be used instead of registering a KeyListener with the component. It is possible to add more than one Channel by calling this method multiple times If the channel passed is null, no action will be taken.

NOTE: This method must be called before this process is run.

Parameters:
keyEvent - the channel down which KeyEvents will be sent.

addMouseEventChannel

public void addMouseEventChannel(ChannelOutput mouseEvent)
Add a new channel to this component that will be used to notify that a MouseEvent has occurred. This should be used instead of registering a MouseListener with the component. It is possible to add more than one Channel by calling this method multiple times If the channel passed is null, no action will be taken.

NOTE: This method must be called before this process is run.

Parameters:
mouseEvent - the channel down which MouseEvents will be sent.

addMouseMotionEventChannel

public void addMouseMotionEventChannel(ChannelOutput mouseMotionEvent)
Add a new channel to this component that will be used to notify that a MouseMotionEvent has occurred. This should be used instead of registering a MouseMotionListener with the component. It is possible to add more than one Channel by calling this method multiple times If the channel passed is null, no action will be taken.

NOTE: This method must be called before this process is run.

Parameters:
mouseMotionEvent - the channel down which MouseMotionEvents will be sent.

run

public void run()
The main body of this process.
Specified by:
run in interface CSProcess

CSP for Java
(JCSP) 1.0-rc4

Submit a bug or feature to jcsp-team@ukc.ac.uk
Version 1.0-rc4 of the JCSP API Specification (Copyright 1997-2000 P.D.Austin and P.H.Welch - All Rights Reserved)
Java is a trademark or registered trademark of Sun Microsystems, Inc. in the US and other countries.