jcsp.awt
Class ActiveTextArea

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.TextComponent
              |
              +--java.awt.TextArea
                    |
                    +--jcsp.awt.ActiveTextArea

All Implemented Interfaces:

Accessible, CSProcess, ImageObserver, MenuContainer, Serializable

public class ActiveTextArea

extends TextArea

implements CSProcess

java.awt.TextArea with a channel interface.

Process Diagram

                              __________________
                             |                  |
                             |                  | event 
                             |                  |----->-----
                             |                  | (java.lang.String)
                             |                  |
                             |                  | componentEvent 
                             |                  |----->-----
                             |                  | (java.awt.event.ComponentEvent)
                             |                  |
                             |                  | focusEvent 
                             |                  |----->-----
                   configure |                  | (java.awt.event.FocusEvent)
                  ----->-----|  ActiveTextArea  |
          (java.lang.String) |                  | keyEvent 
         (java.lang.Boolean) |                  |----->-----
  (ActiveTextArea.Configure) |                  | (java.awt.event.KeyEvent)
          (java.lang.Object) |                  |
                             |                  | mouseEvent 
                             |                  |----->-----
                             |                  | (java.awt.event.MouseEvent)
                             |                  |
                             |                  | mouseMotionEvent 
                             |                  |----->-----
                             |                  | (java.awt.event.MouseEvent)
                             |__________________|  
 

Description

ActiveTextArea is a process extension of java.awt.TextArea 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 and event channels are settable from a constructor. The event channel delivers updated text whenever the ActiveTextArea is changed. Other event channels can be added to notify the occurrence of any other events 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 myTextAreaEvent =
     One2OneChannel.create (new OverWriteOldestBuffer (n));
 
   final ActiveTextArea myTextArea =
     new ActiveTextArea (null, myTextAreaEvent, "Edit Me", 5, 20);
 

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	String	Append the string to the text in this ActiveTextArea
	Boolean	If this is the Boolean.TRUE object, the text area is made active If this is the Boolean.FALSE object, the text area is made inactive Other Boolean objects are ignored
	ActiveTextArea.Configure	Invoke the user-defined Configure.configure method on the textArea.
	otherwise ...	Append the toString form of the object to the text in this ActiveTextArea.
Output Channels
event	String	The text in the ActiveTextArea (whenever the text area is altered)
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 jcsp.lang.*;
 import jcsp.util.*;
 import jcsp.awt.*;
 import java.awt.*;
 
 public class ActiveTextAreaExample {
 
   public static void main (String argv[]) {
 
     final ActiveClosingFrame frame =
       new ActiveClosingFrame ("ActiveTextAreaExample Example");
 
     final Channel event =
       Any2OneChannel.create (new OverWriteOldestBuffer (10));
 
     final String[] string =
       {"Entia Non Sunt Multiplicanda Praeter Necessitatem",
        "Everything we do, we do it to you",
        "Race Hazards - What Rice Hozzers?",
        "Cogito Ergo Occam"};
 
     final String goodbye = "Goodbye World";
 
     final ActiveTextArea[] activeText =
       new ActiveTextArea[string.length];
 
     for (int i = 0; i < string.length; i++) {
       activeText[i] = new ActiveTextArea (null, event, string[i], 5, 20);
     }
 
     Panel panel = new Panel (new GridLayout (string.length/2, 2));
     for (int i = 0; i < string.length; i++) {
       panel.add (activeText[i]);
     }
 
     final Frame realFrame = frame.getActiveFrame ();
     realFrame.setBackground (Color.green);
     realFrame.add (panel);
     realFrame.pack ();
     realFrame.setVisible (true);
 
     new Parallel (
       new CSProcess[] {
         frame,
         new Parallel (activeText),
         new CSProcess () {
           public void run () {
             boolean running = true;
             while (running) {
               String s = (String) event.read ();
               System.out.println (s);
               running = (! s.equals (goodbye));
             }
             realFrame.setVisible (false);
             System.exit (0);
           }
         }
       }
     ).run ();
   }
 
 }
 

Author:

P.D.Austin and P.H.Welch

See Also:

ActiveTextEnterArea, TextArea, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer, Serialized Form

Inner Class Summary

static interface

ActiveTextArea.Configure This enables general configuration of this component.

Inner classes inherited from class java.awt.TextArea

TextArea.AccessibleAWTTextArea

Inner classes inherited from class java.awt.TextComponent

TextComponent.AccessibleAWTTextComponent

Inner classes inherited from class java.awt.Component

Component.AccessibleAWTComponent

Fields inherited from class java.awt.TextArea

SCROLLBARS_BOTH, SCROLLBARS_HORIZONTAL_ONLY, SCROLLBARS_NONE, SCROLLBARS_VERTICAL_ONLY

Fields inherited from class java.awt.TextComponent

textListener

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

ActiveTextArea()
Constructs a new ActiveTextArea with scrollbars, but with no configuration or event channels or initial text or size.

ActiveTextArea(ChannelInput configure, ChannelOutput event)
Constructs a new ActiveTextArea with configuration and event channels and scrollbars, but with no initial text or size.

ActiveTextArea(ChannelInput configure, ChannelOutput event, String s)
Constructs a new ActiveTextArea with configuration and event channels and scrollbars and initial text, but with no initial size.

ActiveTextArea(ChannelInput configure, ChannelOutput event, String s, int rows, int columns)
Constructs a new ActiveTextArea with configuration and event channels and scrollbars and initial text and size.

ActiveTextArea(ChannelInput configure, ChannelOutput event, String s, int rows, int columns, int scrollbars)
Constructs a new ActiveTextArea with configuration and event channels and user-defined scrollbars and initial text and size.

ActiveTextArea(String s)
Constructs a new ActiveTextArea with scrollbars and initial text, but with no configuration or event channels or initial size.

ActiveTextArea(String s, int rows, int columns)
Constructs a new ActiveTextArea with scrollbars and initial text and size, but with no configuration or event channels.

ActiveTextArea(String s, int rows, int columns, int scrollbars)
Constructs a new ActiveTextArea with user-defined scrollbars and initial text and size, but with no configuration or event channels.

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 ActiveTextArea.

Methods inherited from class java.awt.TextArea

addNotify, append, appendText, getAccessibleContext, getColumns, getMinimumSize, getMinimumSize, getPreferredSize, getPreferredSize, getRows, getScrollbarVisibility, insert, insertText, minimumSize, minimumSize, paramString, preferredSize, preferredSize, replaceRange, replaceText, setColumns, setRows

Methods inherited from class java.awt.TextComponent

addTextListener, getBackground, getCaretPosition, getListeners, getSelectedText, getSelectionEnd, getSelectionStart, getText, isEditable, processEvent, processTextEvent, removeNotify, removeTextListener, select, selectAll, setBackground, setCaretPosition, setEditable, setSelectionEnd, setSelectionStart, setText

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getName, getParent, getPeer, 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, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, 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

ActiveTextArea

public ActiveTextArea()

Constructs a new ActiveTextArea with scrollbars, but with no configuration or event channels or initial text or size.

ActiveTextArea

public ActiveTextArea(String s)

Constructs a new ActiveTextArea with scrollbars and initial text, but with no configuration or event channels or initial size.

Parameters:

s - the initial text displayed in the area.

ActiveTextArea

public ActiveTextArea(String s,
                      int rows,
                      int columns)

Constructs a new ActiveTextArea with scrollbars and initial text and size, but with no configuration or event channels.

Parameters:

s - the initial text displayed in the area.

rows - the rows of the area.

columns - the columns of the area.

ActiveTextArea

public ActiveTextArea(String s,
                      int rows,
                      int columns,
                      int scrollbars)

Constructs a new ActiveTextArea with user-defined scrollbars and initial text and size, but with no configuration or event channels.

Parameters:

s - the initial text displayed in the area.

rows - the rows of the area.

columns - the columns of the area.

scrollbars - the columns of the area (java.awt.TextArea.SCROLLBARS_BOTH, java.awt.TextArea.SCROLLBARS_VERTICAL_ONLY, java.awt.TextArea.SCROLLBARS_HORIZONTAL_ONLY or java.awt.TextArea.SCROLLBARS_NONE).

ActiveTextArea

public ActiveTextArea(ChannelInput configure,
                      ChannelOutput event)

Constructs a new ActiveTextArea with configuration and event channels and scrollbars, but with no initial text or size.

Parameters:

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

event - the current text will be output when the text area is changed -- can be null if no notification is required.

ActiveTextArea

public ActiveTextArea(ChannelInput configure,
                      ChannelOutput event,
                      String s)

Constructs a new ActiveTextArea with configuration and event channels and scrollbars and initial text, but with no initial size.

Parameters:

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

event - the current text will be output when the text area is changed -- can be null if no notification is required.

s - the initial text displayed in the area.

ActiveTextArea

public ActiveTextArea(ChannelInput configure,
                      ChannelOutput event,
                      String s,
                      int rows,
                      int columns)

Constructs a new ActiveTextArea with configuration and event channels and scrollbars and initial text and size.

Parameters:

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

event - the current text will be output when the text area is changed -- can be null if no notification is required.

s - the initial text displayed in the area.

rows - the rows of the area.

columns - the columns of the area.

ActiveTextArea

public ActiveTextArea(ChannelInput configure,
                      ChannelOutput event,
                      String s,
                      int rows,
                      int columns,
                      int scrollbars)

Constructs a new ActiveTextArea with configuration and event channels and user-defined scrollbars and initial text and size.

Parameters:

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

event - the current text will be output when the text area is changed -- can be null if no notification is required.

s - the initial text displayed in the area.

rows - the rows of the area.

columns - the columns of the area.

scrollbars - the columns of the area (java.awt.TextArea.SCROLLBARS_BOTH, java.awt.TextArea.SCROLLBARS_VERTICAL_ONLY, java.awt.TextArea.SCROLLBARS_HORIZONTAL_ONLY or java.awt.TextArea.SCROLLBARS_NONE).

Method Detail

setConfigureChannel

public void setConfigureChannel(ChannelInput configure)

Sets the configuration channel for this ActiveTextArea. 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 to send ComponentEvents.

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 to send FocusEvents.

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 to send KeyEvents.

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 to send MouseEvents.

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 to send MouseMotionEvents.

run

public void run()

The main body of this process.

Specified by:

run in interface CSProcess