package org.eclipse.swt.widgets;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved
 */

import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.win32.*;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.events.*;
import java.util.EventListener;

/**
 * This class is the abstract superclass of all user interface objects.  
 * Widgets are created, disposed and issue notification to listeners
 * when events occur which affect them.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>(none)</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Dispose</dd>
 * </dl>
 * <p>
 * IMPORTANT: This class is intended to be subclassed <em>only</em>
 * within the SWT implementation. However, it has not been marked
 * final to allow those outside of the SWT development team to implement
 * patched versions of the class in order to get around specific
 * limitations in advance of when those limitations can be addressed
 * by the team.  Any class built using subclassing to access the internals
 * of this class will likely fail to compile or run between releases and
 * may be strongly platform specific. Subclassing should not be attempted
 * without an intimate and detailed understanding of the workings of the
 * hierarchy. No support is provided for user-written classes which are
 * implemented as subclasses of this class.
 * </p>
 *
 * @see #checkSubclass
 */

public abstract class Widget {

	int style, state;
	EventTable eventTable;
	Object data;
	String [] keys;
	Object [] values;

	/* Global state flags */
//	static final int AUTOMATIC		= 1<<0;
//	static final int ACTIVE			= 1<<1;
//	static final int AUTOGRAB		= 1<<2;
//	static final int MULTIEXPOSE		= 1<<3;
//	static final int RESIZEREDRAW		= 1<<4;
//	static final int WRAP			= 1<<5;
	static final int DISABLED		= 1<<6;
	static final int HIDDEN			= 1<<7;
//	static final int FOREGROUND		= 1<<8;
//	static final int BACKGROUND		= 1<<9;
	static final int DISPOSED		= 1<<10;
//	static final int HANDLE			= 1<<11;
	static final int CANVAS			= 1<<12;
	
	/* Default widths for widgets */
	static final int DEFAULT_WIDTH	= 64;
	static final int DEFAULT_HEIGHT	= 64;
	static final char Mnemonic = '&';

	/* Windows, DBCS and COMCTL32.DLL flags */
	static final boolean IsWinNT, IsDBLocale;
	static final int WIN32_MAJOR, WIN32_MINOR;
	static final int COMCTL32_MAJOR, COMCTL32_MINOR;
	static {

		/* Get the Windows version */
		int version = OS.GetVersion ();
		IsWinNT = (version & 0x80000000) == 0;
		WIN32_MAJOR = version & 0x00FF;
		WIN32_MINOR = (version & 0xFFFF) >> 8;

		/* Get the DBCS flag */
		boolean isDBLocale = false;
		for (int i = 0; i <= 0xFF; i++) {
			if (OS.IsDBCSLeadByte ((byte) i)) {
				isDBLocale = true;
				break;
			}
		}
		IsDBLocale = isDBLocale;

		/* Get the COMCTL32.DLL version */
		DLLVERSIONINFO dvi = new DLLVERSIONINFO ();
		dvi.cbSize = DLLVERSIONINFO.sizeof;
		dvi.dwMajorVersion = 4;
		dvi.dwMinorVersion = 0;
		byte[] lpLibFileName = Converter.wcsToMbcs (0, "comctl32.dll\0");
		int hModule = OS.LoadLibrary (lpLibFileName);
		if (hModule != 0) {
			byte [] lpProcName = Converter.wcsToMbcs (0, "DllGetVersion\0");
			int DllGetVersion = OS.GetProcAddress (hModule, lpProcName);
			if (DllGetVersion != 0) OS.Call (DllGetVersion, dvi);
			OS.FreeLibrary (hModule);
		}
		COMCTL32_MAJOR = dvi.dwMajorVersion;
		COMCTL32_MINOR = dvi.dwMinorVersion;
		if ((COMCTL32_MAJOR << 16 | COMCTL32_MINOR) < (4 << 16 | 71)) {
			System.out.println ("***WARNING: SWT requires comctl32.dll version 4.71 or greater");
		}
		
		/* Initialize the Common Controls DLL */
		OS.InitCommonControls ();
	}
	
/**
 * Prevents uninitialized instances from being created outside the package.
 */
Widget () {
}

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>SWT</code> which is applicable to instances of this
 * class, or must be built by <em>bitwise OR</em>'ing together 
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>SWT</code> style constants. The class description
 * for all SWT widget classes should include a comment which
 * describes the style constants which are applicable to the class.
 * </p>
 *
 * @param parent a widget which will be the parent of the new instance (cannot be null)
 * @param style the style of widget to construct
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see SWT
 * @see #checkSubclass
 * @see #getStyle
 */
public Widget (Widget parent, int style) {
	checkSubclass ();
	checkParent (parent);
	this.style = style;
}

/**
 * Adds the listener to the collection of listeners who will
 * be notifed when an event of the given type occurs. When the
 * event does occur in the widget, the listener is notified by
 * sending it the <code>handleEvent()</code> message.
 *
 * @param eventType the type of event to listen for
 * @param listener the listener which should be notified when the event occurs
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see Listener
 * @see #removeListener
 */
public void addListener (int eventType, Listener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) eventTable = new EventTable ();
	eventTable.hook (eventType, listener);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notifed when the widget is disposed. When the widget is
 * disposed, the listener is notified by sending it the
 * <code>widgetDisposed()</code> message.
 *
 * @param listener the listener which should be notified when the receiver is disposed
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see DisposeListener
 * @see #removeDisposeListener
 */
public void addDisposeListener (DisposeListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener (listener);
	addListener (SWT.Dispose, typedListener);
}

/**
 * Returns a style with exactly one style bit set out of
 * the specified set of exclusive style bits. All other
 * possible bits are cleared when the first matching bit
 * is found. Bits that are not part of the possible set
 * are untouched.
 *
 * @param style the original style bits
 * @param int0 the 0th possible style bit
 * @param int1 the 1st possible style bit
 * @param int2 the 2nd possible style bit
 * @param int3 the 3rd possible style bit
 * @param int4 the 4th possible style bit
 * @param int5 the 5th possible style bit
 *
 * @return the new style bits
 */
static int checkBits (int style, int int0, int int1, int int2, int int3, int int4, int int5) {
	int mask = int0 | int1 | int2 | int3 | int4 | int5;
	if ((style & mask) == 0) style |= int0;
	if ((style & int0) != 0) style = (style & ~mask) | int0;
	if ((style & int1) != 0) style = (style & ~mask) | int1;
	if ((style & int2) != 0) style = (style & ~mask) | int2;
	if ((style & int3) != 0) style = (style & ~mask) | int3;
	if ((style & int4) != 0) style = (style & ~mask) | int4;
	if ((style & int5) != 0) style = (style & ~mask) | int5;
	return style;
}

/**
 * Throws an exception if the specified widget can not be
 * used as a parent for the receiver.
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the parent is disposed</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 */
void checkParent (Widget parent) {
	if (parent == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (!parent.isValidThread ()) error (SWT.ERROR_THREAD_INVALID_ACCESS);
	if (parent.isDisposed()) error (SWT.ERROR_INVALID_ARGUMENT);
}

/**
 * Checks that this class can be subclassed.
 * <p>
 * The SWT class library is intended to be subclassed 
 * only at specific, controlled points (most notably, 
 * <code>Composite</code> and <code>Canvas</code> when
 * implementing new widgets). This method enforces this
 * rule unless it is overridden.
 * </p><p>
 * <em>IMPORTANT:</em> By providing an implementation of this
 * method that allows a subclass of a class which does not 
 * normally allow subclassing to be created, the implementer
 * agrees to be fully responsible for the fact that any such
 * subclass will likely fail between SWT releases and will be
 * strongly platform specific. No support is provided for
 * user-written classes which are implemented in this fashion.
 * </p><p>
 * The ability to subclass outside of the allowed SWT classes,
 * is intended purely to enable those not on the SWT development
 * team to implement patches in order to get around specific
 * limitations in advance of when those limitations can be
 * addressed by the team. Subclassing should not be attempted
 * without an intimate and detailed understanding of the hierarchy.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 */
protected void checkSubclass () {
	if (!isValidSubclass ()) error (SWT.ERROR_INVALID_SUBCLASS);
}

/**
 * Throws an <code>SWTException</code> if the receiver can not
 * be accessed by the caller. This may include both checks on
 * the state of the receiver and more generally on the entire
 * execution context. This method <em>should</em> be called by
 * widget implementors to enforce the standard SWT invariants.
 * <p>
 * Currently, it is an error to invoke any method (other than
 * <code>isDisposed()</code>) on a widget that has had its 
 * <code>dispose()</code> method called. It is also an error
 * to call widget methods from any thread that is different
 * from the thread that created the widget.
 * </p><p>
 * In future releases of SWT, there may be more or fewer error
 * checks and exceptions may be thrown for different reasons.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
protected void checkWidget () {
	if (!isValidThread ()) error (SWT.ERROR_THREAD_INVALID_ACCESS);
	if (isDisposed ()) error (SWT.ERROR_WIDGET_DISPOSED);
}

/**
 * Destroys the widget in the operating system and releases
 * the widget's handle.  If the widget does not have a handle,
 * this method may hide the widget, mark the widget as destroyed
 * or do nothing, depending on the widget.
 * <p>
 * When a widget is destroyed in the operating system, its
 * descendents are also destroyed by the operating system.
 * This means that it is only necessary to call <code>destroyWidget</code>
 * on the root of the widget tree.
 * </p><p>
 * This method is called after <code>releaseWidget</code>.
 * </p>
 * @see #dispose
 * @see #releaseChild
 * @see #releaseWidget
 * @see #releaseHandle
 */
void destroyWidget () {
}

/**
 * Disposes of the operating system resources associated with
 * the receiver and all its descendents. After this method has
 * been invoked, the receiver and all descendents will answer
 * <code>true</code> when sent the message <code>isDisposed()</code>.
 * Any internal connections between the widgets in the tree will
 * have been removed to facilitate garbage collection.
 * <p>
 * NOTE: This method is not called recursively on the descendents
 * of the receiver. This means that, widget implementers can not
 * detect when a widget is being disposed of by re-implementing
 * this method, but should instead listen for the <code>Dispose</code>
 * event.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #addDisposeListener
 * @see #removeDisposeListener
 * @see #checkWidget
 */
public void dispose () {
	/*
	* Note:  It is valid to attempt to dispose a widget
	* more than once.  If this happens, fail silently.
	*/
	if (isDisposed ()) return;
	if (!isValidThread ()) error (SWT.ERROR_THREAD_INVALID_ACCESS);
	releaseChild ();
	releaseWidget ();
	destroyWidget ();
}

/**
 * Does whatever widget specific cleanup is required, and then
 * uses the code in <code>SWTError.error</code> to handle the error.
 *
 * @param code the descriptive error code
 *
 * @see SWTError#error
 */
void error (int code) {
	SWT.error(code);
}

/**
 * Returns the application defined widget data associated
 * with the receiver, or null if it has not been set. The
 * <em>widget data</em> is a single, unnamed field that is
 * stored with every widget. 
 * <p>
 * Applications may put arbitrary objects in this field. If
 * the object stored in the widget data needs to be notified
 * when the widget is disposed of, it is the application's
 * responsibility to hook the Dispose event on the widget and
 * do so.
 * </p>
 *
 * @return the widget data
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - when the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - when called from the wrong thread</li>
 * </ul>
 *
 * @see #setData
 */
public Object getData () {
	checkWidget();
	return data;
}

/**
 * Returns the application defined property of the receiver
 * with the specified name, or null if it has not been set.
 * <p>
 * Applications may have associated arbitrary objects with the
 * receiver in this fashion. If the objects stored in the
 * properties need to be notified when the widget is disposed
 * of, it is the application's responsibility to hook the
 * Dispose event on the widget and do so.
 * </p>
 *
 * @param	key the name of the property
 * @return the value of the property or null if it has not been set
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the key is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #setData
 */
public Object getData (String key) {
	checkWidget();
	if (key == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (keys == null) return null;
	for (int i=0; i<keys.length; i++) {
		if (keys [i].equals (key)) return values [i];
	}
	return null;
}

/**
 * Returns the <code>Display</code> that is associated with
 * the receiver.
 * <p>
 * A widget's display is either provided when it is created
 * (for example, top level <code>Shell</code>s) or is the
 * same as its parent's display.
 * </p>
 *
 * @return the receiver's display
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public abstract Display getDisplay ();

/**
 * Returns the name of the widget. This is the name of
 * the class without the package name.
 *
 * @return the name of the widget
 */
String getName () {
	String string = getClass ().getName ();
	int index = string.lastIndexOf ('.');
	if (index == -1) return string;
	return string.substring (index + 1, string.length ());
}

/*
 * Returns a short printable representation for the contents
 * of a widget. For example, a button may answer the label
 * text. This is used by <code>toString</code> to provide a
 * more meaningful description of the widget.
 *
 * @return the contents string for the widget
 *
 * @see toString
 */
String getNameText () {
	return "";
}

/**
 * Returns the receiver's style information.
 * <p>
 * Note that the value which is returned by this method <em>may
 * not match</em> the value which was provided to the constructor
 * when the receiver was created. This can occur when the underlying
 * operating system does not support a particular combination of
 * requested styles. For example, if the platform widget used to
 * implement a particular SWT widget always has scroll bars, the
 * result of calling this method would always have the
 * <code>SWT.H_SCROLL</code> and <code>SWT.V_SCROLL</code> bits set.
 * </p>
 *
 * @return the style bits
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getStyle () {
	checkWidget();
	return style;
}

/*
 * Returns <code>true</code> if the specified eventType is
 * hooked, and <code>false</code> otherwise. Implementations
 * of SWT can avoid creating objects and sending events
 * when an event happens in the operating system but
 * there are no listeners hooked for the event.
 *
 * @param eventType the event to be checked
 *
 * @return <code>true</code> when the eventType is hooked and <code>false</code> otherwise
 *
 * @see #isListening
 */
boolean hooks (int eventType) {
	if (eventTable == null) return false;
	return eventTable.hooks (eventType);
}

/**
 * Returns <code>true</code> if the widget has been disposed,
 * and <code>false</code> otherwise.
 * <p>
 * This method gets the dispose state for the widget.
 * When a widget has been disposed, it is an error to
 * invoke any other method using the widget.
 * </p>
 *
 * @return <code>true</code> when the widget is disposed and <code>false</code> otherwise
 */
public boolean isDisposed () {
	return (state & DISPOSED) != 0;
}

/**
 * Returns <code>true</code> if there are any listeners
 * for the specified event type associated with the receiver,
 * and <code>false</code> otherwise.
 *
 * @param	eventType the type of event
 * @return true if the event is hooked
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
protected boolean isListening (int eventType) {
	checkWidget();
	return hooks (eventType);
}

/*
 * Returns <code>true</code> when subclassing is
 * allowed and <code>false</code> otherwise
 *
 * @return <code>true</code> when subclassing is allowed and <code>false</code> otherwise
 */
boolean isValidSubclass () {
	return Display.isValidClass (getClass ());
}

/*
 * Returns <code>true</code> when the current thread is
 * the thread that created the widget and <code>false</code>
 * otherwise.
 *
 * @return <code>true</code> when the current thread is the thread that created the widget and <code>false</code> otherwise
 */
boolean isValidThread () {
	return getDisplay ().isValidThread ();
}

/*
 * Returns a single character, converted from the default
 * multi-byte character set (MBCS) used by the operating
 * system widgets to a wide character set (WCS) used by Java.
 *
 * @param ch the MBCS character
 * @return the WCS character
 */
char mbcsToWcs (char ch) {
	return mbcsToWcs (ch, 0);
}

/*
 * Returns a single character, converted from the specified
 * multi-byte character set (MBCS) used by the operating
 * system widgets to a wide character set (WCS) used by Java.
 *
 * @param ch the MBCS character
 * @param codePage the code page used to convert the character
 * @return the WCS character
 */
char mbcsToWcs (char ch, int codePage) {
	int key = ch & 0xFFFF;
	if (key <= 0x7F) return ch;
	byte [] buffer;
	if (key <= 0xFF) {
		buffer = new byte [1];
		buffer [0] = (byte) key;
	} else {
		buffer = new byte [2];
		buffer [0] = (byte) ((key >> 8) & 0xFF);
		buffer [1] = (byte) (key & 0xFF);
	}
	char [] result = Converter.mbcsToWcs (codePage, buffer);
	if (result.length == 0) return 0;
	return result [0];
}

/**
 * Notifies all of the receiver's listeners for events
 * of the given type that one such event has occurred by
 * invoking their <code>handleEvent()</code> method.
 *
 * @param eventType the type of event which has occurred
 * @param event the event data
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the event is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void notifyListeners (int eventType, Event event) {
	checkWidget();
	if (event == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	event.type = eventType;
	event.widget = this;
	eventTable.sendEvent (event);
}

void postEvent (int eventType) {
	if (eventTable == null) return;
	postEvent (eventType, new Event ());
}

void postEvent (int eventType, Event event) {
	if (eventTable == null) return;
	event.type = eventType;
	event.widget = this;
	if (event.time == 0) {
		event.time = OS.GetMessageTime ();
	}
	getDisplay ().postEvent (event);
}

/*
 * Releases the receiver, a child in a widget hierarchy,
 * from its parent.
 * <p>
 * When a widget is destroyed, it may be necessary to remove
 * it from an internal data structure of the parent. When
 * a widget has no handle, it may also be necessary for the
 * parent to hide the widget or otherwise indicate that the
 * widget has been disposed. For example, disposing a menu
 * bar requires that the menu bar first be released from the
 * shell when the menu bar is active.  This could not be done
 * in <code>destroyWidget</code> for the menu bar because the
 * parent shell as well as other fields have been null'd out
 * already by <code>releaseWidget</code>.
 * </p>
 * This method is called first when a widget is disposed.
 * 
 * @see #dispose
 * @see #releaseChild
 * @see #releaseWidget
 * @see #releaseHandle
 */
void releaseChild () {
}

/*
 * Releases the widget's handle by zero'ing it out.
 * Does not destroy or release any operating system
 * resources.
 * <p>
 * This method is called after <code>releaseWidget</code>
 * or from <code>destroyWidget</code> when a widget is being
 * destroyed to ensure that the widget is marked as destroyed
 * in case the act of destroying the widget in the operating
 * system causes application code to run in callback that
 * could access the widget.
 * </p>
 *
 * @see #dispose
 * @see #releaseChild
 * @see #releaseWidget
 * @see #releaseHandle
 */
void releaseHandle () {
}

/*
 * Releases any internal resources back to the operating
 * system and clears all fields except the widget handle.
 * <p>
 * When a widget is destroyed, resources that were acquired
 * on behalf of the programmer need to be returned to the
 * operating system.  For example, if the widget made a
 * copy of an icon, supplied by the programmer, this copy
 * would be freed in <code>releaseWidget</code>.  Also,
 * to assist the garbage collector and minimize the amount
 * of memory that is not reclaimed when the programmer keeps
 * a reference to a disposed widget, all fields except the
 * handle are zero'd.  The handle is needed by <code>destroyWidget</code>.
 * </p>
 * <p>
 * Typically, a widget with children will broadcast this
 * message to all children so that they too can release their
 * resources.  The <code>releaseHandle</code> method is used
 * as part of this broadcast to zero the handle fields of the
 * children without calling <code>destroyWidget</code>.  In
 * this scenario, the children are actually destroyed later,
 * when the operating system destroys the widget tree.
 * </p>
 * This method is called after <code>releaseChild</code>.
 * 
 * @see #dispose
 * @see #releaseChild
 * @see #releaseWidget
 * @see #releaseHandle
 */
void releaseWidget () {
	sendEvent (SWT.Dispose);
	state |= DISPOSED;
	eventTable = null;
	data = null;
	keys = null;
	values = null;
}

/**
 * Removes the listener from the collection of listeners who will
 * be notifed when an event of the given type occurs.
 *
 * @param eventType the type of event to listen for
 * @param listener the listener which should no longer be notified when the event occurs
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see Listener
 * @see #addListener
 */
public void removeListener (int eventType, Listener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (eventType, listener);
}

/**
 * Removes the listener from the collection of listeners who will
 * be notifed when an event of the given type occurs.
 * <p>
 * <b>IMPORTANT:</b> This method is <em>not</em> part of the SWT
 * public API. It is marked public only so that it can be shared
 * within the packages provided by SWT. It should never be
 * referenced from application code.
 * </p>
 *
 * @param eventType the type of event to listen for
 * @param listener the listener which should no longer be notified when the event occurs
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see Listener
 * @see #addListener
 */
protected void removeListener (int eventType, EventListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (eventType, listener);
}

/**
 * Removes the listener from the collection of listeners who will
 * be notifed when the widget is disposed.
 *
 * @param listener the listener which should no longer be notified when the receiver is disposed
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see DisposeListener
 * @see #removeDisposeListener
 */
public void removeDisposeListener (DisposeListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Dispose, listener);
}

void sendEvent (int eventType) {
	if (eventTable == null) return;
	sendEvent (eventType, new Event ());
}

void sendEvent (int eventType, Event event) {
	if (eventTable == null) return;
	event.widget = this;
	event.type = eventType;
	if (event.time == 0) {
		event.time = OS.GetMessageTime ();
	}
	eventTable.sendEvent (event);
}

/**
 * Sets the application defined widget data associated
 * with the receiver to be the argument. The <em>widget
 * data</em> is a single, unnamed field that is stored
 * with every widget. 
 * <p>
 * Applications may put arbitrary objects in this field. If
 * the object stored in the widget data needs to be notified
 * when the widget is disposed of, it is the application's
 * responsibility to hook the Dispose event on the widget and
 * do so.
 * </p>
 *
 * @param data the widget data
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - when the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - when called from the wrong thread</li>
 * </ul>
 */
public void setData (Object data) {
	checkWidget();
	this.data = data;
}

/**
 * Sets the application defined property of the receiver
 * with the specified name to the given value.
 * <p>
 * Applications may associate arbitrary objects with the
 * receiver in this fashion. If the objects stored in the
 * properties need to be notified when the widget is disposed
 * of, it is the application's responsibility to hook the
 * Dispose event on the widget and do so.
 * </p>
 *
 * @param key the name of the property
 * @param value the new value for the property
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the key is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #getData
 */
public void setData (String key, Object value) {
	checkWidget();
	if (key == null) error (SWT.ERROR_NULL_ARGUMENT);
	
	/* Remove the key/value pair */
	if (value == null) {
		if (keys == null) return;
		int index = 0;
		while (index < keys.length && !keys [index].equals (key)) index++;
		if (index == keys.length) return;
		if (keys.length == 1) {
			keys = null;
			values = null;
		} else {
			String [] newKeys = new String [keys.length - 1];
			Object [] newValues = new Object [values.length - 1];
			System.arraycopy (keys, 0, newKeys, 0, index);
			System.arraycopy (keys, index + 1, newKeys, index, newKeys.length - index);
			System.arraycopy (values, 0, newValues, 0, index);
			System.arraycopy (values, index + 1, newValues, index, newValues.length - index);
			keys = newKeys;
			values = newValues;
		}
		return;
	}
	
	/* Add the key/value pair */
	if (keys == null) {
		keys = new String [] {key};
		values = new Object [] {value};
		return;
	}
	for (int i=0; i<keys.length; i++) {
		if (keys [i].equals (key)) {
			values [i] = value;
			return;
		}
	}
	String [] newKeys = new String [keys.length + 1];
	Object [] newValues = new Object [values.length + 1];
	System.arraycopy (keys, 0, newKeys, 0, keys.length);
	System.arraycopy (values, 0, newValues, 0, values.length);
	newKeys [keys.length] = key;
	newValues [values.length] = value;
	keys = newKeys;
	values = newValues;
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the receiver
 */
public String toString () {
	String string = "*Disposed*";
	if (!isDisposed ()) {
		string = "*Wrong Thread*";
		if (isValidThread ()) string = getNameText ();
	}
	return getName () + " {" + string + "}";
}
/*
 * Returns a single character, converted from the wide
 * character set (WCS) used by Java to the default
 * multi-byte character set used by the operating system
 * widgets.
 *
 * @param ch the WCS character
 * @return the MBCS character
 */
char wcsToMbcs (char ch) {
	return wcsToMbcs (ch, 0);
}

/*
 * Returns a single character, converted from the wide
 * character set (WCS) used by Java to the specified
 * multi-byte character set used by the operating system
 * widgets.
 *
 * @param ch the WCS character
 * @param codePage the code page used to convert the character
 * @return the MBCS character
 */
char wcsToMbcs (char ch, int codePage) {
	int key = ch & 0xFFFF;
	if (key <= 0x7F) return ch;
	byte [] buffer = Converter.wcsToMbcs (codePage, new char [] {ch}, false);
	if (buffer.length == 1) return (char) buffer [0];
	if (buffer.length == 2) {
		return (char) (((buffer [0] & 0xFF) << 8) | (buffer [1] & 0xFF));
	}
	return 0;
}

}