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Class jcsp.awt.ActiveCanvas

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Canvas
                   |
                   +----jcsp.awt.ActiveCanvas

public class ActiveCanvas
extends Canvas
implements CSProcess

Process Diagram

  ________________
 |                |
 |  ActiveCanvas  |
 |________________|

Description

An ActiveCanvas is a sub class of Canvas which uses Channels for event notification.

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

Channel Protocols

Input Channels

Output Channels

Example

 import java.awt.*;
 import jcsp.lang.*;
 import jcsp.awt.*;
 public class CanvasExample extends Frame {
   public CanvasExample() {
     super("Canvas Example");
     final Channel event = new One2OneChannel();
     final Channel id = new One2OneChannel();
     ActiveCanvas c = new ActiveCanvas();
     c.addMouseEventChannel(event);
     add(c);
     setVisible(true);
     new Parallel(new CSProcess[] {
       c,
       new EventIDFilter(event, id),
       new CSProcess() {
         public void run() {
           Integer i = (Integer)id.read();
           if (i.intValue() == MouseEvent.MOUSE_CLICKED) {
             setVisible(false);
             System.exit(0);
           }
         }
       }
     }).run();
   }
   public static void main(String argv[]) {
     new CanvasExample();
   }
 }

Author:: P.D.Austin

par: The Parallel construct containing the processes to be executed by this CSProcess.

ActiveCanvas(): Constructs a new ActiveCanvas.

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.

par

 protected Parallel par

The Parallel construct containing the processes to be executed by this CSProcess.

ActiveCanvas

 public ActiveCanvas()

Constructs a new ActiveCanvas.

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.