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//////////////////////////////////////////////////////////////////////
// //
// JCSP ("CSP for Java") Libraries //
// Copyright (C) 1996-2008 Peter Welch and Paul Austin. //
// 2001-2004 Quickstone Technologies Limited. //
// //
// This library is free software; you can redistribute it and/or //
// modify it under the terms of the GNU Lesser General Public //
// License as published by the Free Software Foundation; either //
// version 2.1 of the License, or (at your option) any later //
// version. //
// //
// This library is distributed in the hope that it will be //
// useful, but WITHOUT ANY WARRANTY; without even the implied //
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //
// PURPOSE. See the GNU Lesser General Public License for more //
// details. //
// //
// You should have received a copy of the GNU Lesser General //
// Public License along with this library; if not, write to the //
// Free Software Foundation, Inc., 59 Temple Place, Suite 330, //
// Boston, MA 02111-1307, USA. //
// //
// Author contact: P.H.Welch@kent.ac.uk //
// //
// //
//////////////////////////////////////////////////////////////////////
package org.jcsp.awt;
import java.awt.*;
import java.util.Vector;
import org.jcsp.lang.*;
/**
* {@link java.awt.Label <TT>java.awt.Label</TT>}
* with a channel interface.
* <H2>Process Diagram</H2>
* <p><img src="doc-files/ActiveLabel1.gif"></p>
* <H2>Description</H2>
* <TT>ActiveLabel</TT> is a process extension of <TT>java.awt.Label</TT>
* 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 <I>Listener</I> to this component).
* <P>
* All channels are optional. The <TT>configure</TT> channel is settable from a constructor.
* Event channels can be added to notify the occurrence of any type of <TT>Event</TT>
* the component generates (by calling the appropriate
* <TT>add</TT><I>XXX</I><TT>EventChannel</TT> method <I>before</I> the process is run).
* Messages can be sent down the <TT>configure</TT> channel at any time to configure
* the component. See the <A HREF="#Protocols">table below</A> for details.
* <P>
* 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.
* <P>
* <I>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:</I>
* <PRE>
* final One2OneChannel myMouseEvent = Channel.one2one (new OverWriteOldestBuffer (n));
*
* final ActiveLabel myLabel = new ActiveLabel ("Look at Me");
* myContainer.addMouseEventChannel (myMouseEvent.out ());
* </PRE>
* <I>This will ensure that the Java Event Thread will never be blocked.
* Slow or inattentive readers may miss rapidly generated events, but
* the </I><TT>n</TT><I> most recent events will always be available.</I>
* </P>
* <H2><A NAME="Protocols">Channel Protocols</A></H2>
* <CENTER>
* <TABLE BORDER="2">
* <TR>
* <TH COLSPAN="3">Input Channels</TH>
* </TR>
* <TR>
* <TH ROWSPAN="3">configure</TH>
* <TD>String</TD>
* <TD>Change the label on the <TT>ActiveLabel</TT> to the value of the <TT>String</TT></TD>
* </TR>
* <TR>
* <TD>Boolean</TD>
* <TD>
* <OL>
* <LI>If this is the <TT>Boolean.TRUE</TT> object,
* the label is made active</LI>
* <LI>If this is the <TT>Boolean.FALSE</TT> object,
* the label is made inactive</LI>
* <LI>Other <TT>Boolean</TT> objects are ignored</LI>
* </OL>
* </TD>
* </TR>
* <TR>
* <TD>ActiveLabel.Configure</TD>
* <TD>Invoke the user-defined <TT>Configure.configure</TT> method on the label.</TD>
* </TR>
* <TR>
* <TH COLSPAN="3">Output Channels</TH>
* </TR>
* <TR>
* <TH>componentEvent</TH>
* <TD>ComponentEvent</TD>
* <TD>See the {@link #addComponentEventChannel
* <TT>addComponentEventChannel</TT>} method.</TD>
* </TR>
* <TR>
* <TH>focusEvent</TH>
* <TD>FocusEvent</TD>
* <TD>See the {@link #addFocusEventChannel
* <TT>addFocusEventChannel</TT>} method.</TD>
* </TR>
* <TR>
* <TH>keyEvent</TH>
* <TD>KeyEvent</TD>
* <TD>See the {@link #addKeyEventChannel
* <TT>addKeyEventChannel</TT>} method.</TD>
* </TR>
* <TR>
* <TH>mouseEvent</TH>
* <TD>MouseEvent</TD>
* <TD>See the {@link #addMouseEventChannel
* <TT>addMouseEventChannel</TT>} method.</TD>
* </TR>
* <TR>
* <TH>mouseMotionEvent</TH>
* <TD>MouseEvent</TD>
* <TD>See the {@link #addMouseMotionEventChannel
* <TT>addMouseMotionEventChannel</TT>} method.</TD>
* </TR>
* </TABLE>
* </CENTER>
* <H2>Example</H2>
* <PRE>
* import java.awt.*;
* import org.jcsp.lang.*;
* import org.jcsp.util.*;
* import org.jcsp.awt.*;
*
* public class ActiveLabelExample {
*
* public static void main (String argv[]) {
*
* final Frame root = new Frame ("ActiveLabel Example");
*
* final int nLabels = 8;
* final int countdown = 10;
*
* final One2OneChannel[] configureLabel = Channel.one2oneArray (nLabels);
*
* final ActiveLabel[] label = new ActiveLabel[nLabels];
* for (int i = 0; i < label.length; i++) {
* label[i] = new ActiveLabel (configureLabel[i].in (), "==> " + countdown + " <==");
* label[i].setAlignment (Label.CENTER);
* }
*
* final One2OneChannel configureButton = Channel.one2one ();
* final One2OneChannel event = Channel.one2one (new OverWriteOldestBuffer (10));
*
* final ActiveButton button = new ActiveButton (configureButton.in (), event.out (), "Start");
*
* root.setSize (300, 200);
* root.setLayout (new GridLayout (3, 3));
* for (int i = 0; i < nLabels + 1; i++) {
* if (i < 4) {
* root.add (label[i]);
* } else if (i == 4) {
* root.add (button);
* } else if (i > 4) {
* root.add (label[i - 1]);
* }
* }
* root.setVisible (true);
*
* new Parallel (
* new CSProcess[] {
* new Parallel (label),
* button,
* new CSProcess () {
* public void run () {
* final long second = 1000;
* CSTimer tim = new CSTimer ();
* Alternative alt = new Alternative (new Guard[] {event.in (), tim});
* event.in ().read (); // wait for the start signal
* configureButton.out ().write ("Restart");
* int count = countdown;
* long timeout = tim.read () + second;
* while (count > 0) {
* tim.setAlarm (timeout);
* switch (alt.priSelect ()) {
* case 0: // reset signal
* event.in ().read (); // clear the reset
* timeout = tim.read () + second;
* count = countdown;
* break;
* case 1: // timeout signal
* timeout += second;
* count--;
* break;
* }
* final String newLabel = "==> " + count + " <==";
* for (int i = 0; i < nLabels; i++) {
* configureLabel[i].out ().write (newLabel);
* }
* }
* root.setVisible (false);
* System.exit (0);
* }
* }
* }
* ).run ();
*
* }
*
* }
* </PRE>
*
* @see java.awt.Label
* @see java.awt.event.ComponentEvent
* @see java.awt.event.FocusEvent
* @see java.awt.event.KeyEvent
* @see java.awt.event.MouseEvent
* @see org.jcsp.util.OverWriteOldestBuffer
*
* @author P.D. Austin and P.H. Welch
*/
public class ActiveLabel extends Label implements CSProcess
{
/**
* The Vector construct containing the handlers.
*/
private Vector vec = new Vector();
/**
* The channel from which configuration messages arrive.
*/
private ChannelInput configure;
/**
* Constructs a new <TT>ActiveLabel</TT> with no label or configuration channel.
*/
public ActiveLabel()
{
this("");
}
/**
* Constructs a new <TT>ActiveLabel</TT> with no configuration channel.
*
* @param s the initial string displayed on the label.
*/
public ActiveLabel(String s)
{
this(null, s);
}
/**
* Constructs a new <TT>ActiveLabel</TT> with no initial label.
*
* @param configure the channel for configuration events
* -- can be null if no configuration is required.
*/
public ActiveLabel(ChannelInput configure)
{
this(configure, "");
}
/**
* Constructs a new <TT>ActiveLabel</TT>.
*
* @param configure the channel for configuration events
* -- can be null if no configuration is required.
* @param s the initial string displayed on the label.
*/
public ActiveLabel(ChannelInput configure, String s)
{
super(s);
this.configure = configure;
}
/**
* Sets the configuration channel for this <TT>ActiveLabel</TT>.
* This method overwrites any configuration channel set in the constructor.
*
* @param configure the channel for configuration events
* -- can be null if no configuration is required.
*/
public void setConfigureChannel(ChannelInput configure)
{
this.configure = configure;
}
/**
* Add a new channel to this component that will be used to notify that
* a <TT>ComponentEvent</TT> has occurred. <I>This should be used
* instead of registering a ComponentListener with the component.</I> It is
* possible to add more than one channel by calling this method multiple times
* If the channel passed is <TT>null</TT>, no action will be taken.
* <P>
* <I>NOTE: This method must be called before this process is run.</I>
*
* @param componentEvent the channel down which to send ComponentEvents.
*/
public void addComponentEventChannel(ChannelOutput componentEvent)
{
if (componentEvent != null)
{
ComponentEventHandler handler = new ComponentEventHandler(componentEvent);
addComponentListener(handler);
vec.addElement(handler);
}
}
/**
* Add a new channel to this component that will be used to notify that
* a <TT>FocusEvent</TT> has occurred. <I>This should be used
* instead of registering a FocusListener with the component.</I> It is
* possible to add more than one channel by calling this method multiple times
* If the channel passed is <TT>null</TT>, no action will be taken.
* <P>
* <I>NOTE: This method must be called before this process is run.</I>
*
* @param focusEvent the channel down which to send FocusEvents.
*/
public void addFocusEventChannel(ChannelOutput focusEvent)
{
if (focusEvent != null)
{
FocusEventHandler handler = new FocusEventHandler(focusEvent);
addFocusListener(handler);
vec.addElement(handler);
}
}
/**
* Add a new channel to this component that will be used to notify that
* a <TT>KeyEvent</TT> has occurred. <I>This should be used
* instead of registering a KeyListener with the component.</I> It is
* possible to add more than one channel by calling this method multiple times
* If the channel passed is <TT>null</TT>, no action will be taken.
* <P>
* <I>NOTE: This method must be called before this process is run.</I>
*
* @param keyEvent the channel down which to send KeyEvents.
*/
public void addKeyEventChannel(ChannelOutput keyEvent)
{
if (keyEvent != null)
{
KeyEventHandler handler = new KeyEventHandler(keyEvent);
addKeyListener(handler);
vec.addElement(handler);
}
}
/**
* Add a new channel to this component that will be used to notify that
* a <TT>MouseEvent</TT> has occurred. <I>This should be used
* instead of registering a MouseListener with the component.</I> It is
* possible to add more than one channel by calling this method multiple times
* If the channel passed is <TT>null</TT>, no action will be taken.
* <P>
* <I>NOTE: This method must be called before this process is run.</I>
*
* @param mouseEvent the channel down which to send MouseEvents.
*/
public void addMouseEventChannel(ChannelOutput mouseEvent)
{
if (mouseEvent != null)
{
MouseEventHandler handler = new MouseEventHandler(mouseEvent);
addMouseListener(handler);
vec.addElement(handler);
}
}
/**
* Add a new channel to this component that will be used to notify that
* a <TT>MouseMotionEvent</TT> has occurred. <I>This should be used
* instead of registering a MouseMotionListener with the component.</I> It is
* possible to add more than one channel by calling this method multiple times
* If the channel passed is <TT>null</TT>, no action will be taken.
* <P>
* <I>NOTE: This method must be called before this process is run.</I>
*
* @param mouseMotionEvent the channel down which to send MouseMotionEvents.
*/
public void addMouseMotionEventChannel(ChannelOutput mouseMotionEvent)
{
if (mouseMotionEvent != null)
{
MouseMotionEventHandler handler = new MouseMotionEventHandler(mouseMotionEvent);
addMouseMotionListener(handler);
vec.addElement(handler);
}
}
/**
* This enables general configuration of this component. Any object implementing
* this interface and sent down the <TT>configure</TT> channel to this component will have its
* <TT>configure</TT> method invoked on this component.
* <P>
* For an example, see {@link ActiveApplet.Configure}.
*/
static public interface Configure
{
/**
* @param label the Label being configured.
*/
public void configure(final Label label);
}
/**
* The main body of this process.
*/
public void run()
{
if (configure != null)
{
while (true)
{
Object message = configure.read();
if (message instanceof String)
setText((String) message);
else if (message instanceof Boolean)
{
if (message == Boolean.TRUE)
setEnabled(true);
else if (message == Boolean.FALSE)
setEnabled(false);
}
else if (message instanceof Configure)
((Configure) message).configure(this);
}
}
}
}
|