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