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//////////////////////////////////////////////////////////////////////
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// JCSP ("CSP for Java") Libraries //
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// Copyright (C) 1996-2008 Peter Welch and Paul Austin. //
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// 2001-2004 Quickstone Technologies Limited. //
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// This library is free software; you can redistribute it and/or //
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// modify it under the terms of the GNU Lesser General Public //
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// License as published by the Free Software Foundation; either //
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// version 2.1 of the License, or (at your option) any later //
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// This library is distributed in the hope that it will be //
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// useful, but WITHOUT ANY WARRANTY; without even the implied //
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// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //
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// PURPOSE. See the GNU Lesser General Public License for more //
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// You should have received a copy of the GNU Lesser General //
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// Public License along with this library; if not, write to the //
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// Free Software Foundation, Inc., 59 Temple Place, Suite 330, //
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// Boston, MA 02111-1307, USA. //
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// Author contact: P.H.Welch@kent.ac.uk //
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//////////////////////////////////////////////////////////////////////
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import java.util.Vector;
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import org.jcsp.lang.*;
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* {@link java.awt.TextField <TT>java.awt.TextField</TT>}
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* with a channel interface.
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* <H2>Process Diagram</H2>
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* <p><img src="doc-files/ActiveTextField1.gif"></p>
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* <H2>Description</H2>
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* <TT>ActiveTextField</TT> is a process extension of <TT>java.awt.TextField</TT>
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* with channels for run-time configuration and event notification. The event channels
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* should be connected to one or more application-specific server processes (instead
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* of registering a passive object as a <I>Listener</I> to this component).
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* All channels are optional. The <TT>configure</TT> and <TT>event</TT> channels are
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* settable from a constructor.
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* The <TT>event</TT> channel delivers updated text whenever
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* the <TT>ActiveTextField</TT> is changed.
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* Other event channels can be added to notify the occurrence of any other events
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* the component generates (by calling the appropriate
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* <TT>add</TT><I>XXX</I><TT>EventChannel</TT> method <I>before</I> the process is run).
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* Messages can be sent down the <TT>configure</TT> channel at any time to configure
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* the component. See the <A HREF="#Protocols">table below</A> for details.
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* All channels are managed by independent internal handler processes. It is, therefore,
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* safe for a serial application process both to service an event channel and configure
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* the component -- no deadlock can occur.
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* <I>IMPORTANT: it is essential that event channels from this process are
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* always serviced -- otherwise the Java Event Thread will be blocked and the GUI
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* will stop responding. A simple way to guarantee this is to use channels
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* configured with overwriting buffers.
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* final One2OneChannel myTextFieldEvent = Channel.one2one (new OverWriteOldestBuffer (n));
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* final ActiveTextField myTextField =
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* new ActiveTextField (null, myTextFieldEvent.out (), "Edit Me");
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* <I>This will ensure that the Java Event Thread will never be blocked.
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* Slow or inattentive readers may miss rapidly generated events, but
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* the </I><TT>n</TT><I> most recent events will always be available.</I>
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* <H2><A NAME="Protocols">Channel Protocols</A></H2>
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* <TH COLSPAN="3">Input Channels</TH>
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* <TH ROWSPAN="4">configure</TH>
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* <TD>Set the text in this <TT>ActiveTextField</TT> to the value of the <TT>String</TT></TD>
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* <LI>If this is the <TT>Boolean.TRUE</TT> object,
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* the text field is made active</LI>
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* <LI>If this is the <TT>Boolean.FALSE</TT> object,
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* the text field is made inactive</LI>
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* <LI>Other <TT>Boolean</TT> objects are ignored</LI>
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* <TD>ActiveTextField.Configure</TD>
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* <TD>Invoke the user-defined <TT>Configure.configure</TT> method on the textField.</TD>
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* <TD><I>otherwise</I></TD>
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* <TD>Append the <TT>toString</TT> form of the object to the text in this <TT>ActiveTextField</TT>.</TD>
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* <TH COLSPAN="3">Output Channels</TH>
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* <TD>The text in the <TT>ActiveTextField</TT> (whenever the text field is altered)</TD>
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* <TH>componentEvent</TH>
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* <TD>ComponentEvent</TD>
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* <TD>See the {@link #addComponentEventChannel
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* <TT>addComponentEventChannel</TT>} method.</TD>
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* <TH>focusEvent</TH>
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* <TD>FocusEvent</TD>
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* <TD>See the {@link #addFocusEventChannel
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* <TT>addFocusEventChannel</TT>} method.</TD>
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* <TD>See the {@link #addKeyEventChannel
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* <TT>addKeyEventChannel</TT>} method.</TD>
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* <TH>mouseEvent</TH>
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* <TD>MouseEvent</TD>
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* <TD>See the {@link #addMouseEventChannel
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* <TT>addMouseEventChannel</TT>} method.</TD>
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* <TH>mouseMotionEvent</TH>
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* <TD>MouseEvent</TD>
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* <TD>See the {@link #addMouseMotionEventChannel
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* <TT>addMouseMotionEventChannel</TT>} method.</TD>
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* import org.jcsp.lang.*;
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* import org.jcsp.util.*;
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* import org.jcsp.awt.*;
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* public class ActiveTextFieldExample {
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* public static void main (String argv[]) {
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* final ActiveClosingFrame frame =
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* new ActiveClosingFrame ("ActiveTextFieldExample Example");
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* final Any2OneChannel event = Channel.any2one (new OverWriteOldestBuffer (10));
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* final String[] string =
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* {"Entia Non Sunt Multiplicanda Praeter Necessitatem",
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* "Less is More ... More or Less",
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* "Everything we do, we do it to you",
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* "Race Hazards - What Rice Hozzers?",
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* "Cogito Ergo Occam"};
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* final String goodbye = "Goodbye World";
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* final ActiveTextField[] activeText =
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* new ActiveTextField[string.length];
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* for (int i = 0; i < string.length; i++) {
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* activeText[i] = new ActiveTextField (null, event.out (), string[i]);
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* Panel panel = new Panel (new GridLayout (string.length, 1));
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* for (int i = 0; i < string.length; i++) {
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* panel.add (activeText[i]);
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* final Frame realFrame = frame.getActiveFrame ();
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* realFrame.setBackground (Color.green);
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* realFrame.add (panel);
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* realFrame.setVisible (true);
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* new Parallel (activeText),
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* public void run () {
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* boolean running = true;
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* String s = (String) event.in ().read ();
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* System.out.println (s);
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* running = (! s.equals (goodbye));
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* realFrame.setVisible (false);
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* @see org.jcsp.awt.ActiveTextEnterField
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* @see java.awt.TextField
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* @see java.awt.event.ComponentEvent
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* @see java.awt.event.FocusEvent
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* @see java.awt.event.KeyEvent
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* @see java.awt.event.MouseEvent
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* @see org.jcsp.util.OverWriteOldestBuffer
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* @author P.D. Austin and P.H. Welch
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public class ActiveTextField extends TextField implements CSProcess
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* The Vector construct containing the handlers.
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private Vector vec = new Vector();
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* The channel from which configuration messages arrive.
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private ChannelInput configure;
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* Constructs a new <TT>ActiveTextField</TT> with no initial text,
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* configuration or event channels.
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public ActiveTextField()
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this(null, null, "", 0);
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* Constructs a new <TT>ActiveTextField</TT> with initial text and default width,
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* but no configuration or event channels.
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* @param s the initial text displayed in the field.
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public ActiveTextField(String s)
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this(null, null, s, s.length());
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* Constructs a new <TT>ActiveTextField</TT> with initial text and width,
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* but no configuration or event channels.
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* @param s the initial text displayed in the field.
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* @param columns the width of the field.
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public ActiveTextField(String s, int columns)
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this(null, null, s, columns);
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* Constructs a new <TT>ActiveTextField</TT> with configuration and event channels,
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* but no initial text.
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* @param configure the channel for configuration events
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* -- can be null if no configuration is required.
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* @param event the current text will be output when the text field is changed
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* -- can be null if no notification is required.
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public ActiveTextField(ChannelInput configure, ChannelOutput event)
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this(configure, event, "", 0);
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* Constructs a new <TT>ActiveTextField</TT> with configuration and event channels,
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* initial text and default width.
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* @param configure the channel for configuration events
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* -- can be null if no configuration is required.
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* @param event the current text will be output when the text field is changed
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* -- can be null if no notification is required.
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* @param s the initial text displayed in the field.
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public ActiveTextField(ChannelInput configure, ChannelOutput event, String s)
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this(configure, event, s, s.length());
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* Constructs a new <TT>ActiveTextField</TT> with configuration and event channels,
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* initial text and width.
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* @param configure the channel for configuration events
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* -- can be null if no configuration is required.
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* @param event the current text will be output when the text field is changed
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* -- can be null if no notification is required.
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* @param s the initial text displayed in the field.
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* @param columns the width of the field.
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public ActiveTextField(ChannelInput configure, ChannelOutput event, String s, int columns)
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// Only create an event handler if the event Channel is not null.
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TextEventHandler handler = new TextEventHandler(event);
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addTextListener(handler);
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vec.addElement(handler);
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this.configure = configure;
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* Sets the configuration channel for this <TT>ActiveTextField</TT>.
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* This method overwrites any configuration channel set in the constructor.
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* @param configure the channel for configuration events.
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* If the channel passed is <TT>null</TT>, no action will be taken.
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public void setConfigureChannel(ChannelInput configure)
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this.configure = configure;
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* Add a new channel to this component that will be used to notify that
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* a <TT>ComponentEvent</TT> has occurred. <I>This should be used
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* instead of registering a ComponentListener with the component.</I> It is
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* possible to add more than one channel by calling this method multiple times
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* If the channel passed is <TT>null</TT>, no action will be taken.
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* <I>NOTE: This method must be called before this process is run.</I>
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* @param componentEvent the channel down which to send ComponentEvents.
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public void addComponentEventChannel(ChannelOutput componentEvent)
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if (componentEvent != null)
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ComponentEventHandler handler = new ComponentEventHandler(componentEvent);
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addComponentListener(handler);
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vec.addElement(handler);
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* Add a new channel to this component that will be used to notify that
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* a <TT>FocusEvent</TT> has occurred. <I>This should be used
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* instead of registering a FocusListener with the component.</I> It is
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* possible to add more than one channel by calling this method multiple times
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* If the channel passed is <TT>null</TT>, no action will be taken.
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* <I>NOTE: This method must be called before this process is run.</I>
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* @param focusEvent the channel down which to send FocusEvents.
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public void addFocusEventChannel(ChannelOutput focusEvent)
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if (focusEvent != null)
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FocusEventHandler handler = new FocusEventHandler(focusEvent);
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addFocusListener(handler);
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vec.addElement(handler);
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* Add a new channel to this component that will be used to notify that
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* a <TT>KeyEvent</TT> has occurred. <I>This should be used
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* instead of registering a KeyListener with the component.</I> It is
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* possible to add more than one channel by calling this method multiple times
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* If the channel passed is <TT>null</TT>, no action will be taken.
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* <I>NOTE: This method must be called before this process is run.</I>
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* @param keyEvent the channel down which to send KeyEvents.
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public void addKeyEventChannel(ChannelOutput keyEvent)
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if (keyEvent != null)
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KeyEventHandler handler = new KeyEventHandler(keyEvent);
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addKeyListener(handler);
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vec.addElement(handler);
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* Add a new channel to this component that will be used to notify that
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* a <TT>MouseEvent</TT> has occurred. <I>This should be used
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* instead of registering a MouseListener with the component.</I> It is
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* possible to add more than one channel by calling this method multiple times
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* If the channel passed is <TT>null</TT>, no action will be taken.
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* <I>NOTE: This method must be called before this process is run.</I>
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* @param mouseEvent the channel down which to send MouseEvents.
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public void addMouseEventChannel(ChannelOutput mouseEvent)
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if (mouseEvent != null)
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MouseEventHandler handler = new MouseEventHandler(mouseEvent);
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addMouseListener(handler);
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vec.addElement(handler);
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* Add a new channel to this component that will be used to notify that
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* a <TT>MouseMotionEvent</TT> has occurred. <I>This should be used
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* instead of registering a MouseMotionListener with the component.</I> It is
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* possible to add more than one channel by calling this method multiple times
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* If the channel passed is <TT>null</TT>, no action will be taken.
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* <I>NOTE: This method must be called before this process is run.</I>
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* @param mouseMotionEvent the channel down which to send MouseMotionEvents.
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public void addMouseMotionEventChannel(ChannelOutput mouseMotionEvent)
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if (mouseMotionEvent != null)
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MouseMotionEventHandler handler = new MouseMotionEventHandler(mouseMotionEvent);
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addMouseMotionListener(handler);
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vec.addElement(handler);
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* This enables general configuration of this component. Any object implementing
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* this interface and sent down the <TT>configure</TT> channel to this component will have its
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* <TT>configure</TT> method invoked on this component.
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* For an example, see {@link ActiveApplet.Configure}.
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static public interface Configure
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* @param textField the TextField being configured.
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public void configure(final TextField textField);
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* The main body of this process.
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if (configure != null)
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Object message = configure.read();
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if (message instanceof String)
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setText((String) message);
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else if (message instanceof Boolean)
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if (message == Boolean.TRUE)
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else if (message == Boolean.FALSE)
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else if (message instanceof Configure)
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((Configure) message).configure(this);
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setText(message.toString());
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src/org/jcsp/awt/ActiveTextField.java
