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Class jcsp.awt.ActiveScrollbar 

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Scrollbar
                   |
                   +----jcsp.awt.ActiveScrollbar
public class ActiveScrollbar
extends Scrollbar
implements CSProcess

Process Diagram

External View

             _________________
  configure |                 | event
 ----->-----| ActiveScrollbar |--->---
            |_________________|

Internal View

             ______________________________________________
            |  ____________      ________________________  |
  configure | |            |    |                        | | event
 ----->-------|  Configure |    | AdjustmentEventHandler |----->---
            | |____________|    |________________________| |
            |                                              |
            |                              ActiveScrollbar |
            |______________________________________________|

Description

An ActiveScrollbar is a sub class of Scrollbar which uses Channels for event notification and configuration.

If the event Channel is not a null reference an new AdjustmentEventHandler is created with the Channel and is registered as AdjustmentListener with the ActiveScrollbar and has its adjustmentValueChanged() method invoked when AdjustmentEvents are generated. Any events generated when the AdjustmentEventHandler is blocked writing to the event Channel are ignored so that the main Java Event Thread is not blocked. The output from the AdjustmentEventHanlder is connected to the event Channel causing an Object to be sent down the Channel when the Scrollbar is adjusted.

It is also possible to register Channels to be used to notify the occurrence of other types of Event that the Scrollbar generates. This can be done by calling one of the addXXXXEventChannel() methods.

To configure the Scrollbar messages can be sent down the configure channel. If the configure Channel is not a null reference a new Configure is created. The configure process sits in an infinite loop which reads from the configure Channel and configures the component based on the Object received (see table below for details).

Channel Protocols

Input Channels
configure Integer Sets the value of the scroll bar to the value of the Integer
Boolean
  1. If the Boolean Object refers to the Boolean.TRUE instance the button is made active
  2. If the Boolean Object refers to the Boolean.FALSE instance the button is made inactive
  3. If the Boolean Object refers to any other Boolean instance the message is discarded
Output Channels
event Integer The Integer representing the current value of the Scrollbar that generated the event.

Author:
P.D.Austin

Constructor Index

o ActiveScrollbar()
Constructs a vertical Scrollbar with no configuration Channel and no event Channel.
o ActiveScrollbar(Channel, Channel)
Constructs a vertical Scrollbar with the configuration Channel configure and the event Channel event.
o ActiveScrollbar(Channel, Channel, int)
Constructs a Scrollbar with the specified orientation, the configuration Channel configure and the event Channel event.
o ActiveScrollbar(Channel, Channel, int, int, int, int, int)
Constructs a Scrollbar with the specified orientation, initial value, page size, and minimum and maximum values, the configuration Channel configure and the event Channel event.
o ActiveScrollbar(int)
Constructs a Scrollbar with the specified orientation, no configuration Channel and no event Channel.
o ActiveScrollbar(int, int, int, int, int)
Constructs a Scrollbar with the specified orientation, initial value, page size, and minimum and maximum values, no configuration Channel and no event Channel.

Method Index

o addComponentEventChannel(ChannelOutput)
Add a new Channel to the Component which will be used to notify that a ComponentEvent has occurred on the component.
o addFocusEventChannel(ChannelOutput)
Add a new Channel to the Component which will be used to notify that a FocusEvent has occurred on the component.
o addKeyEventChannel(ChannelOutput)
Add a new Channel to the Component which will be used to notify that a KeyEvent has occurred on the component.
o addMouseEventChannel(ChannelOutput)
Add a new Channel to the Component which will be used to notify that a MouseEvent has occurred on the component.
o addMouseMotionEventChannel(ChannelOutput)
Add a new Channel to the Component which will be used to notify that a MouseMotionEvent has occurred on the component.
o run()
The main body of this process.

Constructors

o ActiveScrollbar 
 public ActiveScrollbar()
Constructs a vertical Scrollbar with no configuration Channel and no event Channel.

Parameters:
configure - The Channel configuration events should be sent down. Can be null if no configuration is required.
event - The Channel events will be notified down when the button is pressed. Can be null if events are going to be ignored.
o ActiveScrollbar 
 public ActiveScrollbar(int orientation)
Constructs a Scrollbar with the specified orientation, no configuration Channel and no event Channel.

Parameters:
configure - The Channel configuration events should be sent down. Can be null if no configuration is required.
event - The Channel events will be notified down when the button is pressed. Can be null if events are going to be ignored.
orientation - indicates the orientation of the scroll bar.
o ActiveScrollbar 
 public ActiveScrollbar(int orientation,
                        int value,
                        int visible,
                        int minimum,
                        int maximum)
Constructs a Scrollbar with the specified orientation, initial value, page size, and minimum and maximum values, no configuration Channel and no event Channel.

Parameters:
orientation - indicates the orientation of the scroll bar.
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.
o ActiveScrollbar 
 public ActiveScrollbar(Channel configure,
                        Channel event)
Constructs a vertical Scrollbar with the configuration Channel configure and the event Channel event.

Parameters:
configure - The Channel configuration events should be sent down. Can be null if no configuration is required.
event - The Channel events will be notified down when the button is pressed. Can be null if events are going to be ignored.
o ActiveScrollbar 
 public ActiveScrollbar(Channel configure,
                        Channel event,
                        int orientation)
Constructs a Scrollbar with the specified orientation, the configuration Channel configure and the event Channel event.

Parameters:
configure - The Channel configuration events should be sent down. Can be null if no configuration is required.
event - The Channel events will be notified down when the button is pressed. Can be null if events are going to be ignored.
orientation - indicates the orientation of the scroll bar.
o ActiveScrollbar 
 public ActiveScrollbar(Channel configure,
                        Channel event,
                        int orientation,
                        int value,
                        int visible,
                        int minimum,
                        int maximum)
Constructs a Scrollbar with the specified orientation, initial value, page size, and minimum and maximum values, the configuration Channel configure and the event Channel event.

Parameters:
configure - The Channel configuration events should be sent down. Can be null if no configuration is required.
event - The Channel events will be notified down when the button is pressed. Can be null if events are going to be ignored.
orientation - indicates the orientation of the scroll bar.
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.

Methods

o addComponentEventChannel 
 public void addComponentEventChannel(ChannelOutput componentEvent)
Add a new Channel to the Component which will be used to notify that a ComponentEvent has occurred on the component. 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 reference passed is null no action will be taken. Otherwise a new ComponentEventHanlder will be generated for the Channel so that each Channel operates independently of the others.

NOTE: This method must be called before this process is run otherwise it will not function correctly.

Parameters:
componentEvent - The channel to send component events down. If the Channel is to be shared with other events it should be a Many2OneChannel.
See Also:
ComponentEventHandler
o addFocusEventChannel 
 public void addFocusEventChannel(ChannelOutput focusEvent)
Add a new Channel to the Component which will be used to notify that a FocusEvent has occurred on the component. 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 reference passed is null no action will be taken. Otherwise a new FocusEventHanlder will be generated for the Channel so that each Channel operates independently of the others.

NOTE: This method must be called before this process is run otherwise it will not function correctly.

Parameters:
focusEvent - The channel to send focus events down. If the Channel is to be shared with other events it should be a Many2OneChannel.
See Also:
FocusEventHandler
o addKeyEventChannel 
 public void addKeyEventChannel(ChannelOutput keyEvent)
Add a new Channel to the Component which will be used to notify that a KeyEvent has occurred on the component. 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 reference passed is null no action will be taken. Otherwise a new KeyEventHanlder will be generated for the Channel so that each Channel operates independently of the others.

NOTE: This method must be called before this process is run otherwise it will not function correctly.

Parameters:
keyEvent - The channel to send key events down. If the Channel is to be shared with other events it should be a Many2OneChannel.
See Also:
KeyEventHandler
o addMouseEventChannel 
 public void addMouseEventChannel(ChannelOutput mouseEvent)
Add a new Channel to the Component which will be used to notify that a MouseEvent has occurred on the component. 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 reference passed is null no action will be taken. Otherwise a new MouseEventHanlder will be generated for the Channel so that each Channel operates independently of the others.

NOTE: This method must be called before this process is run otherwise it will not function correctly.

Parameters:
mouseEvent - The channel to send key events down. If the Channel is to be shared with other events it should be a Many2OneChannel.
See Also:
MouseEventHandler
o addMouseMotionEventChannel 
 public void addMouseMotionEventChannel(ChannelOutput mouseMotionEvent)
Add a new Channel to the Component which will be used to notify that a MouseMotionEvent has occurred on the component. 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 reference passed is null no action will be taken. Otherwise a new MouseMotionEventHanlder will be generated for the Channel so that each Channel operates independently of the others.

NOTE: This method must be called before this process is run otherwise it will not function correctly.

Parameters:
mouseMotionEvent - The channel to send key events down. If the Channel is to be shared with other events it should be a Many2OneChannel.
See Also:
MouseMotionEventHandler
o run 
 public void run()
The main body of this process. 

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