Package org.jcsp.awt

Class ActiveLabel

  • All Implemented Interfaces:
    java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable, javax.accessibility.Accessible, CSProcess

    public class ActiveLabel
    extends java.awt.Label
    implements CSProcess
    java.awt.Label with a channel interface.

    Process Diagram

    Description

    ActiveLabel is a process extension of java.awt.Label 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 = Channel.one2one (new OverWriteOldestBuffer (n));
     
       final ActiveLabel myLabel = new ActiveLabel ("Look at Me");
       myContainer.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 String Change the label on the ActiveLabel to the value of the String
    Boolean
    1. If this is the Boolean.TRUE object, the label is made active
    2. If this is the Boolean.FALSE object, the label is made inactive
    3. Other Boolean objects are ignored
    ActiveLabel.Configure Invoke the user-defined Configure.configure method on the label.
    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 org.jcsp.lang.*;
     import org.jcsp.util.*;
     import org.jcsp.awt.*;
     
     public class ActiveLabelExample {
     
       public static void main (String argv[]) {
     
         final Frame root = new Frame ("ActiveLabel Example");
     
         final int nLabels = 8;
         final int countdown = 10;
     
         final One2OneChannel[] configureLabel = Channel.one2oneArray (nLabels);
     
         final ActiveLabel[] label = new ActiveLabel[nLabels];
         for (int i = 0; i < label.length; i++) {
           label[i] = new ActiveLabel (configureLabel[i].in (), "==>  " + countdown + "  <==");
           label[i].setAlignment (Label.CENTER);
         }
     
         final One2OneChannel configureButton = Channel.one2one ();
         final One2OneChannel event = Channel.one2one (new OverWriteOldestBuffer (10));
     
         final ActiveButton button = new ActiveButton (configureButton.in (), event.out (), "Start");
     
         root.setSize (300, 200);
         root.setLayout (new GridLayout (3, 3));
         for (int i = 0; i < nLabels + 1; i++) {
           if (i < 4) {
             root.add (label[i]);
           } else if (i == 4) {
             root.add (button);
           } else if (i > 4) {
             root.add (label[i - 1]);
           }
         }
         root.setVisible (true);
     
         new Parallel (
           new CSProcess[] {
             new Parallel (label),
             button,
             new CSProcess () {
               public void run () {
                 final long second = 1000;
                 CSTimer tim = new CSTimer ();
                 Alternative alt = new Alternative (new Guard[] {event.in (), tim});
                 event.in ().read ();              // wait for the start signal
                 configureButton.out ().write ("Restart");
                 int count = countdown;
                 long timeout = tim.read () + second;
                 while (count > 0) {
                   tim.setAlarm (timeout);
                   switch (alt.priSelect ()) {
                     case 0:                 // reset signal
                       event.in ().read ();        // clear the reset
                       timeout = tim.read () + second;
                       count = countdown;
                     break;
                     case 1:                 // timeout signal
                       timeout += second;
                       count--;
                     break;
                   }
                   final String newLabel = "==>  " + count + "  <==";
                   for (int i = 0; i < nLabels; i++) {
                     configureLabel[i].out ().write (newLabel);
                   }
                 }
                 root.setVisible (false);
                 System.exit (0);
               }
             }
           }
         ).run ();
     
       }
     
     }
     
    Author:
    P.D. Austin and P.H. Welch
    See Also:
    Label, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer, Serialized Form
    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static interface  ActiveLabel.Configure
      This enables general configuration of this component.
      • Nested classes/interfaces inherited from class java.awt.Label

        java.awt.Label.AccessibleAWTLabel
      • Nested classes/interfaces inherited from class java.awt.Component

        java.awt.Component.AccessibleAWTComponent, java.awt.Component.BaselineResizeBehavior, java.awt.Component.BltBufferStrategy, java.awt.Component.FlipBufferStrategy
    • Field Summary

      • Fields inherited from class java.awt.Label

        CENTER, LEFT, RIGHT
      • Fields inherited from class java.awt.Component

        accessibleContext, 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

      Constructors 
      Constructor Description
      ActiveLabel()
      Constructs a new ActiveLabel with no label or configuration channel.
      ActiveLabel​(java.lang.String s)
      Constructs a new ActiveLabel with no configuration channel.
      ActiveLabel​(ChannelInput configure)
      Constructs a new ActiveLabel with no initial label.
      ActiveLabel​(ChannelInput configure, java.lang.String s)
      Constructs a new ActiveLabel.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      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 ActiveLabel.
      • Methods inherited from class java.awt.Label

        addNotify, getAccessibleContext, getAlignment, getText, paramString, setAlignment, setText
      • Methods inherited from class java.awt.Component

        action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPreferredSize, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, 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, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setMixingCutoutShape, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Constructor Detail

      • ActiveLabel

        public ActiveLabel()
        Constructs a new ActiveLabel with no label or configuration channel.
      • ActiveLabel

        public ActiveLabel​(java.lang.String s)
        Constructs a new ActiveLabel with no configuration channel.
        Parameters:
        s - the initial string displayed on the label.
      • ActiveLabel

        public ActiveLabel​(ChannelInput configure)
        Constructs a new ActiveLabel with no initial label.
        Parameters:
        configure - the channel for configuration events -- can be null if no configuration is required.
      • ActiveLabel

        public ActiveLabel​(ChannelInput configure,
                           java.lang.String s)
        Constructs a new ActiveLabel.
        Parameters:
        configure - the channel for configuration events -- can be null if no configuration is required.
        s - the initial string displayed on the label.
    • Method Detail

      • setConfigureChannel

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