org.jcsp.awt
Class ActiveScrollbar

java.lang.Object
  java.awt.Component
      java.awt.Scrollbar
          org.jcsp.awt.ActiveScrollbar

All Implemented Interfaces:

Adjustable, ImageObserver, MenuContainer, Serializable, Accessible, CSProcess

public class ActiveScrollbar
extends Scrollbar
implements CSProcess

java.awt.Scrollbar with a channel interface.

Process Diagram

Description

ActiveScrollbar is a process extension of java.awt.Scrollbar 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 the adjusted value whenever the ActiveScrollbar is moved. 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 One2OneChannelInt myScrollbarEvent = Channel.one2oneInt (new OverWriteOldestBuffer (n));
 
   final ActiveScrollbar myScrollbar =
     new ActiveScrollbar (null, myScrollbarEvent.out (), Scrollbar.HORIZONTAL, 0, 10, 0, 110);
 

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	Integer	Sets the value of the scrollbar to the value received
	Boolean	If this is the Boolean.TRUE object, the scrollbar is made active If this is the Boolean.FALSE object, the scrollbar is made inactive Other Boolean objects are ignored
	ActiveScrollbar.Configure	Invoke the user-defined Configure.configure method on the scrollbar.
Output Channels
event	int	The new value of the scrollbar
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 org.jcsp.lang.*;
 import org.jcsp.util.ints.*;
 import org.jcsp.awt.*;
 
 public class ActiveScrollbarExample {
 
   public static void main (String argv[]) {
 
     final ActiveClosingFrame activeFrame = new ActiveClosingFrame ("ActiveScrollbar Example");
 
     final One2OneChannel configure = Channel.one2one ();
     final One2OneChannelInt scrollEvent = Channel.one2oneInt (new OverWriteOldestBufferInt (10));
 
     final ActiveScrollbar scrollBar =
       new ActiveScrollbar (
         null, scrollEvent.out (), Scrollbar.HORIZONTAL, 0, 10, 0, 110
       );
 
     final Frame realFrame = activeFrame.getActiveFrame ();
     realFrame.setSize (400, 75);
     realFrame.add (scrollBar);
     realFrame.setVisible (true);
 
     new Parallel (
       new CSProcess[] {
         activeFrame,
         scrollBar,
         new CSProcess () {
           public void run () {
             final long FREE_TIME = 10000, BUSY_TIME = 250;
             CSTimer tim = new CSTimer ();
             Alternative alt = new Alternative (new Guard[] {tim, scrollEvent.in ()});
             final int TIM = 0, SCROLL = 1;
             long timeout = tim.read ();
             tim.setAlarm (timeout + FREE_TIME);
             boolean running = true;
             while (running) {
               switch (alt.priSelect ()) {
                 case TIM:                                     // timeout happened
                   configure.out ().write (Boolean.FALSE);     // disable scrollbar
                   for (int i = 40; i > 0; i--) {
                     System.out.println ("*** busy busy busy ... " + i);
                     timeout = tim.read ();
                     tim.after (timeout + BUSY_TIME);
                   }
                   System.out.println ("*** free free free ... 0");
                   configure.out ().write (Boolean.TRUE);      // enable scrollbar
                   timeout = tim.read ();
                   tim.setAlarm (timeout + FREE_TIME);
                 break;
                 case SCROLL:                                  // scrollEvent happened
                   int position = scrollEvent.in ().read ();
                   System.out.println ("ScrollBar ==> " + position);
                   running = (position != 100);
                 break;
               }
             }
             realFrame.setVisible (false);
             System.exit (0);
           }
         }
       }
     ).run ();
   }
 
 }
 

Author:

P.D. Austin and P.H. Welch

See Also:

Scrollbar, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer, Serialized Form

Nested Class Summary

static interface

ActiveScrollbar.Configure This enables general configuration of this component.

Nested classes/interfaces inherited from class java.awt.Scrollbar

Scrollbar.AccessibleAWTScrollBar

Nested classes/interfaces inherited from class java.awt.Component

Component.AccessibleAWTComponent, Component.BltBufferStrategy, Component.FlipBufferStrategy

Field Summary

Fields inherited from class java.awt.Scrollbar

HORIZONTAL, VERTICAL

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.Adjustable

NO_ORIENTATION

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

ActiveScrollbar()
Constructs a vertical ActiveScrollbar with no configuration or event channels.

ActiveScrollbar(ChannelInput configure, ChannelOutputInt event)
Constructs a vertical ActiveScrollbar with configuration and event channels.

ActiveScrollbar(ChannelInput configure, ChannelOutputInt event, int orientation)
Constructs a ActiveScrollbar with configuration and event channels and the specified orientation.

ActiveScrollbar(ChannelInput configure, ChannelOutputInt event, int orientation, int value, int visible, int minimum, int maximum)
Constructs a ActiveScrollbar with configuration and event channels and all its options.

ActiveScrollbar(int orientation)
Constructs a ActiveScrollbar with the specified orientation, but still with no configuration or event channels.

ActiveScrollbar(int orientation, int value, int visible, int minimum, int maximum)
Constructs a ActiveScrollbar with all its options, but still 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 ActiveScrollbar.

Methods inherited from class java.awt.Scrollbar

addAdjustmentListener, addNotify, getAccessibleContext, getAdjustmentListeners, getBlockIncrement, getLineIncrement, getListeners, getMaximum, getMinimum, getOrientation, getPageIncrement, getUnitIncrement, getValue, getValueIsAdjusting, getVisible, getVisibleAmount, paramString, processAdjustmentEvent, processEvent, removeAdjustmentListener, setBlockIncrement, setLineIncrement, setMaximum, setMinimum, setOrientation, setPageIncrement, setUnitIncrement, setValue, setValueIsAdjusting, setValues, setVisibleAmount

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, 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, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, 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, 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, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, 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

ActiveScrollbar

public ActiveScrollbar()

Constructs a vertical ActiveScrollbar with no configuration or event channels.

ActiveScrollbar

public ActiveScrollbar(int orientation)

Constructs a ActiveScrollbar with the specified orientation, but still with no configuration or event channels. The minimum and maximum values default to 0 and 100, with the initial setting at 0.

Parameters:

orientation - indicates the orientation of the scroll bar (Scrollbar.VERTICAL, Scrollbar.HORIZONTAL).

ActiveScrollbar

public ActiveScrollbar(int orientation,
                       int value,
                       int visible,
                       int minimum,
                       int maximum)

Constructs a ActiveScrollbar with all its options, but still with no configuration or event channels.

Parameters:

orientation - indicates the orientation of the scroll bar (Scrollbar.VERTICAL, Scrollbar.HORIZONTAL).

value - the initial value of the scroll bar.

visible - the size of the scroll bar's bubble, representing the visible portion; the scroll bar uses this value when paging up or down by a page.

minimum - the minimum value of the scroll bar.

maximum - the maximum value of the scroll bar.

ActiveScrollbar

public ActiveScrollbar(ChannelInput configure,
                       ChannelOutputInt event)

Constructs a vertical ActiveScrollbar with configuration and event channels. The minimum and maximum values default to 0 and 100, with the initial setting at 0.

Parameters:

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

event - the adjusted value will be output when the scrollbar is moved -- can be null if no notification is required.

ActiveScrollbar

public ActiveScrollbar(ChannelInput configure,
                       ChannelOutputInt event,
                       int orientation)

Constructs a ActiveScrollbar with configuration and event channels and the specified orientation. The minimum and maximum values default to 0 and 100, with the initial setting at 0.

Parameters:

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

event - the adjusted value will be output when the scrollbar is moved -- can be null if no notification is required.

orientation - indicates the orientation of the scroll bar (Scrollbar.VERTICAL, Scrollbar.HORIZONTAL).

ActiveScrollbar

public ActiveScrollbar(ChannelInput configure,
                       ChannelOutputInt event,
                       int orientation,
                       int value,
                       int visible,
                       int minimum,
                       int maximum)

Constructs a ActiveScrollbar with configuration and event channels and all its options.

Parameters:

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

event - the adjusted value will be output when the scrollbar is moved -- can be null if no notification is required.

orientation - indicates the orientation of the scroll bar (Scrollbar.VERTICAL, Scrollbar.HORIZONTAL).

value - the initial value of the scroll bar.

visible - the size of the scroll bar's bubble, representing the visible portion; the scroll bar uses this value when paging up or down by a page.

minimum - the minimum value of the scroll bar.

maximum - the maximum value of the scroll bar.

Method Detail

setConfigureChannel

public void setConfigureChannel(ChannelInput configure)

Sets the configuration channel for this ActiveScrollbar. 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