Package org.jcsp.awt

Class ActiveFrame

  • All Implemented Interfaces:
    ImageObserver, MenuContainer, Serializable, Accessible, CSProcess

    public class ActiveFrame
    extends Frame
    implements CSProcess
    java.awt.Frame with a channel interface.

    Process Diagram

    Description

    ActiveFrame is a process extension of java.awt.Frame 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 a WindowEvent whenever one is generated on the ActiveFrame. 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 One2OneChannel myWindowEvent = Channel.one2one (new OverWriteOldestBuffer (n));
       final One2OneChannel myMouseEvent = Channel.one2one (new OverWriteOldestBuffer (n));
     
       final ActiveFrame myFrame = new ActiveFrame (myWindowEvent.out ());
       myFrame.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 Boolean
    1. If this is the Boolean.TRUE object, the frame is made visible
    2. If this is the Boolean.FALSE object, the frame is made invisible
    3. Other Boolean objects are ignored
    ActiveFrame.Configure Invoke the user-defined Configure.configure method on the frame.
    Output Channels
    event WindowEvent The WindowEvent generated by the component
    containerEvent ContainerEvent See the addContainerEventChannel method.
    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.*;
     import org.jcsp.awt.*;
     
     public class ActiveFrameButtonExample {
     
       public static void main (String argv[]) {
     
         final Any2OneChannel windowEvent = Channel.any2one (new OverWriteOldestBuffer (10));
     
         final ActiveFrame frame =
           new ActiveFrame (null, windowEvent.out (), "ActiveButton Example");
     
         final String[] label = {"Hello World", "Rocket Science", "CSP",
                                 "Monitors", "Ignore Me", "Goodbye World"};
     
         final Any2OneChannel buttonEvent = Channel.any2one (new OverWriteOldestBuffer (10));
     
         final ActiveButton[] button = new ActiveButton[label.length];
         for (int i = 0; i < label.length; i++) {
           button[i] = new ActiveButton (null, buttonEvent.out (), label[i]);
         }
     
         frame.setSize (300, 200);
         frame.setLayout (new GridLayout (label.length/2, 2));
         for (int i = 0; i < label.length; i++) {
           frame.add (button[i]);
         }
         frame.setVisible (true);
     
         new Parallel (
           new CSProcess[] {
             new Parallel (button),
             new CSProcess () {                 // respond to window events
               public void run () {
                 boolean running = true;
                 while (running) {
                   final WindowEvent w = (WindowEvent) windowEvent.in ().read ();
                   System.out.println ("Window event: " + w);
                   running = (w.getID () != WindowEvent.WINDOW_CLOSING);
                 }
                 frame.setVisible (false);
                 System.exit (0);
               }
             },
             new CSProcess () {                 // respond to button events
               public void run () {
                 boolean running = true;
                 while (running) {
                   final String s = (String) buttonEvent.in ().read ();
                   System.out.println ("Button `" + s + "' pressed ...");
                   running = (s != label[label.length - 1]);
                 }
                 frame.setVisible (false);
                 System.exit (0);
               }
             }
           }
         ).run ();
     
       }
     
     }
     
    Author:
    P.D. Austin and P.H. Welch
    See Also:
    ActiveClosingFrame, Frame, ContainerEvent, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer, Serialized Form
    • Constructor Detail

      • ActiveFrame

        public ActiveFrame()
        Constructs a new ActiveFrame with no title and no configuration or event channels.
      • ActiveFrame

        public ActiveFrame​(String title)
        Constructs a new ActiveFrame with a title but no configuration or event channels.
        Parameters:
        title - the title for the frame.
      • ActiveFrame

        public ActiveFrame​(ChannelInput configure,
                           ChannelOutput event)
        Constructs a new ActiveFrame with configuration and event channels, but no title.
        Parameters:
        configure - the channel for configuration events -- can be null if no configuration is required.
        event - a WindowEvent will be output whenever it occurs -- can be null if no notification is required.
      • ActiveFrame

        public ActiveFrame​(ChannelInput configure,
                           ChannelOutput event,
                           String title)
        Constructs a new ActiveFrame with configuration and event channels and a title.
        Parameters:
        configure - the channel for configuration events -- can be null if no configuration is required.
        event - a WindowEvent will be output whenever it occurs -- can be null if no notification is required.
        title - the title for the frame.
    • Method Detail

      • setConfigureChannel

        public void setConfigureChannel​(ChannelInput configure)
        Sets the configuration channel for this ActiveFrame. 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.
      • addContainerEventChannel

        public void addContainerEventChannel​(ChannelOutput containerEvent)
        Add a new channel to this component that will be used to notify that a ContainerEvent has occurred. This should be used instead of registering a ContainerListener 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:
        containerEvent - the channel down which to send ContainerEvents.
      • 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