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Class jcsp.awt.ActiveTextField

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.TextComponent
                   |
                   +----java.awt.TextField
                           |
                           +----jcsp.awt.ActiveTextField

public class ActiveTextField
extends TextField
implements CSProcess

Process Diagram

External View

             __________________
  configure |                  | event
 ----->-----|  ActiveTextField |--->---
            |__________________|

Internal View

             ________________________________________
            |  ____________      __________________  |
  configure | |            |    |                  | | event
 ----->-------|  Configure |    | TextEventHandler |----->---
            | |____________|    |__________________| |
            |                                        |
            |                        ActiveTextField |
            |________________________________________|

Description

An ActiveTextField is a sub class of TextField which uses Channels for event notification and configuration.

If the event Channel is not a null reference an new TextEventHandler is created with the Channel and is registered as TextListener with the ActiveTextField and has its textValueChanged() method invoked when TextEvents are generated. Any events generated when the TextEventHandler is blocked writing to the event Channel are ignored so that the main Java Event Thread is not blocked. The output from the TextEventHanlder is connected to the event Channel causing an Object to be sent down the Channel when the TextField is changed.

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

To configure the TextField 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	String	Sets the text in the TextField to the String
configure	Boolean	If the Boolean Object refers to the Boolean.TRUE instance the button is made active If the Boolean Object refers to the Boolean.FALSE instance the button is made inactive If the Boolean Object refers to any other Boolean instance the message is discarded
Output Channels
event	String	The text in the ActiveTextField

Example

 import java.awt.*;
 import jcsp.lang.*;
 import jcsp.awt.*;
 public class TextFieldExample extends Frame {
   public TextFieldExample() {
     super("TextField Example");
     final Channel close = new One2OneChannel();
     ActiveTextField t = new ActiveTextField(null, close, "");
     add(t);
     setVisible(true);
     new Parallel(new CSProcess[] {
       t,
       new CSProcess() {
         public void run() {
           String s = (String)close.read();
           is (s.equals("close")) {
             setVisible(false);
             System.exit(0);
           }
         }
       }
     }).run();
   }
   public static void main(String argv[]) {
     new TextFieldExample();
   }
 }

Author:: P.D.Austin
See Also:: TextEventHandler

ActiveTextField(): Constructs a new TextField with no initial value, no configuration Channel and no event Channel.
ActiveTextField(ChannelInput, ChannelOutput): Constructs a new TextField with no initial value, configuration Channel configure and the event Channel event.
ActiveTextField(ChannelInput, ChannelOutput, String): Constructs a new TextField with the initial value s, configuration Channel configure and the event Channel event.
ActiveTextField(ChannelInput, ChannelOutput, String, int): Constructs a new TextArea with the initial value s, and the specified columns, configuration Channel configure and the event Channel event.
ActiveTextField(String): Constructs a new TextField with the initial value s, no configuration Channel and no event Channel.
ActiveTextField(String, int): Constructs a new TextField with the initial value s, and the specified columns, no configuration Channel and no event Channel.

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

ActiveTextField

 public ActiveTextField()

Constructs a new TextField with no initial value, no configuration Channel and no event Channel.

ActiveTextField

 public ActiveTextField(String s)

Constructs a new TextField with the initial value s, no configuration Channel and no event Channel.

Parameters:: s - The inital value shown in the TextArea

ActiveTextField

 public ActiveTextField(String s,
                        int columns)

Constructs a new TextField with the initial value s, and the specified columns, no configuration Channel and no event Channel.

Parameters:: s - The inital value shown in the TextArea; columns - The width in number of characters

ActiveTextField

 public ActiveTextField(ChannelInput configure,
                        ChannelOutput event)

Constructs a new TextField with no initial value, 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.

ActiveTextField

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

Constructs a new TextField with the initial value s, 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.; s - The inital value shown in the TextArea

ActiveTextField

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

Constructs a new TextArea with the initial value s, and the specified columns, 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.; s - The inital value shown in the TextArea; columns - The width in number of characters

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.