bundles/org.eclipse.swt/Eclipse SWT/emulated/expand/org/eclipse/swt/widgets/ExpandBar.java - platform/eclipse.platform.swt - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2009 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.swt.widgets;

 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.events.*;

 /**
  * Instances of this class support the layout of selectable
  * expand bar items.
  * <p>
  * The item children that may be added to instances of this class
  * must be of type <code>ExpandItem</code>.
  * </p><p>
  * <dl>
  * <dt><b>Styles:</b></dt>
  * <dd>V_SCROLL</dd>
  * <dt><b>Events:</b></dt>
  * <dd>Expand, Collapse</dd>
  * </dl>
  * </p><p>
  * IMPORTANT: This class is <em>not</em> intended to be subclassed.
  * </p>
  *
  * @see ExpandItem
  * @see ExpandEvent
  * @see ExpandListener
  * @see ExpandAdapter
  * @see <a href="http://www.eclipse.org/swt/snippets/#expandbar">ExpandBar snippets</a>
  * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a>
  * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
  *
  * @since 3.2
  * @noextend This class is not intended to be subclassed by clients.
  */
 public class ExpandBar extends Composite {
 	ExpandItem [] items;
 	int itemCount;
 	ExpandItem focusItem;
 	int spacing;
 	int yCurrentScroll;
 	Font font;
 	Color foreground;
 	Listener listener;
 	boolean inDispose;

 /**
  * 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
  * lists the style constants that are applicable to the class.
  * Style bits are also inherited from superclasses.
  * </p>
  *
  * @param parent a composite control which will be the parent of the new instance (cannot be null)
  * @param style the style of control 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#V_SCROLL
  * @see Widget#checkSubclass
  * @see Widget#getStyle
  */
 public ExpandBar (Composite parent, int style) {
 	super (parent, checkStyle (style));
 	items = new ExpandItem [4];

 	listener = new Listener () {
 		public void handleEvent (Event event) {
 			switch (event.type) {
 				case SWT.Dispose:		onDispose (event);        	break;
 				case SWT.MouseDown:		onMouseDown (event);   		break;
 				case SWT.MouseUp:		onMouseUp (event);   		break;
 				case SWT.Paint:			onPaint (event);     		break;
 				case SWT.Resize:		onResize ();     			break;
 				case SWT.KeyDown:		onKeyDown (event);    		break;
 				case SWT.FocusIn:		onFocus ();     			break;
 				case SWT.FocusOut:		onFocus ();     			break;
 				case SWT.Traverse:		onTraverse (event);   		break;
 			}
 		}
 	};
 	addListener (SWT.Dispose, listener);
 	addListener (SWT.MouseDown, listener);
 	addListener (SWT.MouseUp, listener);
 	addListener (SWT.Paint, listener);
 	addListener (SWT.Resize, listener);
 	addListener (SWT.KeyDown, listener);
 	addListener (SWT.FocusIn, listener);
 	addListener (SWT.FocusOut, listener);
 	addListener (SWT.Traverse, listener);

 	ScrollBar verticalBar = getVerticalBar ();
 	if (verticalBar != null) {
 		verticalBar.addListener (SWT.Selection, new Listener () {
 			public void handleEvent (Event event) {
 				onScroll (event);
 			}
 		});
 	}
 }

 /**
  * Adds the listener to the collection of listeners who will
  * be notified when an item in the receiver is expanded or collapsed
  * by sending it one of the messages defined in the <code>ExpandListener</code>
  * interface.
  *
  * @param listener the listener which should be notified
  *
  * @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 ExpandListener
  * @see #removeExpandListener
  */
 public void addExpandListener (ExpandListener listener) {
 	checkWidget ();
 	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
 	TypedListener typedListener = new TypedListener (listener);
 	addListener (SWT.Expand, typedListener);
 	addListener (SWT.Collapse, typedListener);
 }

 static int checkStyle (int style) {
 	return style & ~SWT.H_SCROLL;
 }

 protected void checkSubclass () {
 	if (!isValidSubclass ()) error (SWT.ERROR_INVALID_SUBCLASS);
 }

 public Point computeSize (int wHint, int hHint, boolean changed) {
 	checkWidget ();
 	int height = 0, width = 0;
 	if (wHint == SWT.DEFAULT || hHint == SWT.DEFAULT) {
 		if (itemCount > 0) {
 			height += spacing;
 			GC gc = new GC (this);
 			for (int i = 0; i < itemCount; i++) {
 				ExpandItem item = items [i];
 				height += item.getHeaderHeight ();
 				if (item.expanded) height += item.height;
 				height += spacing;
 				width = Math.max (width, item.getPreferredWidth (gc));
 			}
 			gc.dispose ();
 		}
 	}
 	if (width == 0) width = DEFAULT_WIDTH;
 	if (height == 0) height = DEFAULT_HEIGHT;
 	if (wHint != SWT.DEFAULT) width = wHint;
 	if (hHint != SWT.DEFAULT) height = hHint;
 	Rectangle trim = computeTrim (0, 0, width, height);
 	return new Point (trim.width, trim.height);
 }

 void createItem (ExpandItem item, int style, int index) {
 	if (!(0 <= index && index <= itemCount)) error (SWT.ERROR_INVALID_RANGE);
 	if (itemCount == items.length) {
 		ExpandItem [] newItems = new ExpandItem [itemCount + 4];
 		System.arraycopy (items, 0, newItems, 0, items.length);
 		items = newItems;
 	}
 	System.arraycopy (items, index, items, index + 1, itemCount - index);
 	items [index] = item;
 	itemCount++;
 	if (focusItem == null) focusItem = item;
 	item.width = Math.max (0, getClientArea ().width - spacing * 2);
 	layoutItems (index, true);
 }

 void destroyItem (ExpandItem item) {
 	if (inDispose) return;
 	int index = 0;
 	while (index < itemCount) {
 		if (items [index] == item) break;
 		index++;
 	}
 	if (index == itemCount) return;
 	if (item == focusItem) {
 		int focusIndex = index > 0 ? index - 1 : 1;
 		if (focusIndex < itemCount) {
 			focusItem = items [focusIndex];
 			focusItem.redraw ();
 		} else {
 			focusItem = null;
 		}
 	}
 	System.arraycopy (items, index + 1, items, index, --itemCount - index);
 	items [itemCount] = null;
 	item.redraw ();
 	layoutItems (index, true);
 }

 int getBandHeight () {
 	if (font == null) return ExpandItem.CHEVRON_SIZE;
 	GC gc = new GC (this);
 	FontMetrics metrics = gc.getFontMetrics ();
 	gc.dispose ();
 	return Math.max (ExpandItem.CHEVRON_SIZE, metrics.getHeight ());
 }

 public Color getForeground () {
 	checkWidget ();
 	if (foreground == null) {
 		Display display = getDisplay ();
 		return display.getSystemColor (SWT.COLOR_TITLE_FOREGROUND);
 	}
 	return foreground;
 }

 /**
  * Returns the item at the given, zero-relative index in the
  * receiver. Throws an exception if the index is out of range.
  *
  * @param index the index of the item to return
  * @return the item at the given index
  *
  * @exception IllegalArgumentException <ul>
  *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list minus 1 (inclusive)</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 ExpandItem getItem (int index) {
 	checkWidget ();
 	if (!(0 <= index && index < itemCount)) error (SWT.ERROR_INVALID_RANGE);
 	return items [index];
 }

 /**
  * Returns the number of items contained in the receiver.
  *
  * @return the number of items
  *
  * @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 getItemCount () {
 	checkWidget ();
 	return itemCount;
 }

 /**
  * Returns an array of <code>ExpandItem</code>s which are the items
  * in the receiver.
  * <p>
  * Note: This is not the actual structure used by the receiver
  * to maintain its list of items, so modifying the array will
  * not affect the receiver.
  * </p>
  *
  * @return the items in the receiver
  *
  * @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 ExpandItem [] getItems () {
 	checkWidget ();
 	ExpandItem [] result = new ExpandItem [itemCount];
 	System.arraycopy (items, 0, result, 0, itemCount);
 	return result;
 }

 /**
  * Returns the receiver's spacing.
  *
  * @return the spacing
  *
  * @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 getSpacing () {
 	checkWidget ();
 	return spacing;
 }

 /**
  * Searches the receiver's list starting at the first item
  * (index 0) until an item is found that is equal to the
  * argument, and returns the index of that item. If no item
  * is found, returns -1.
  *
  * @param item the search item
  * @return the index of the item
  *
  * @exception IllegalArgumentException <ul>
  *    <li>ERROR_NULL_ARGUMENT - if the item is null</li>
  *    <li>ERROR_INVALID_ARGUMENT - if the item has been disposed</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 int indexOf (ExpandItem item) {
 	checkWidget ();
 	if (item == null) error (SWT.ERROR_NULL_ARGUMENT);
 	for (int i = 0; i < itemCount; i++) {
 		if (items [i] == item) return i;
 	}
 	return -1;
 }

 void layoutItems (int index, boolean setScrollbar) {
 	if (index < itemCount) {
 		int y = spacing - yCurrentScroll;
 		for (int i = 0; i < index; i++) {
 			ExpandItem item = items [i];
 			if (item.expanded) y += item.height;
 			y += item.getHeaderHeight() + spacing;
 		}
 		for (int i = index; i < itemCount; i++) {
 			ExpandItem item = items [i];
 			item.setBounds (spacing, y, 0, 0, true, false);
 			if (item.expanded) y += item.height;
 			y += item.getHeaderHeight() + spacing;
 		}
 	}
 	if (setScrollbar) setScrollbar ();
 }

 /**
  * Removes the listener from the collection of listeners who will
  * be notified when items in the receiver are expanded or collapsed.
  *
  * @param listener the listener which should no longer be notified
  *
  * @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 ExpandListener
  * @see #addExpandListener
  */
 public void removeExpandListener (ExpandListener listener) {
 	checkWidget ();
 	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
 	if (eventTable == null) return;
 	eventTable.unhook (SWT.Expand, listener);
 	eventTable.unhook (SWT.Collapse, listener);
 }

 void reskinChildren (int flags) {
 	if (items != null) {
 		for (int i=0; i<items.length; i++) {
 			ExpandItem item = items [i];
 			if (item != null ) item.reskin (flags);
 		}
 	}
 	super.reskinChildren (flags);
 }

 public void setFont(Font font) {
 	super.setFont (font);
 	this.font = font;
 	layoutItems (0, true);
 }

 public void setForeground (Color color) {
 	super.setForeground (color);
 	foreground = color;
 }

 void setScrollbar () {
 	if (itemCount == 0) return;
 	ScrollBar verticalBar = getVerticalBar ();
 	if (verticalBar == null) return;
 	int height = getClientArea ().height;
 	ExpandItem item = items [itemCount - 1];
 	int maxHeight = item.y + getBandHeight () + spacing;
 	if (item.expanded) maxHeight += item.height;

 	//claim bottom free space
 	if (yCurrentScroll > 0 && height > maxHeight) {
 		yCurrentScroll = Math.max (0, yCurrentScroll + maxHeight - height);
 		layoutItems (0, false);
 	}
 	maxHeight += yCurrentScroll;

 	int selection = Math.min (yCurrentScroll, maxHeight);
 	int increment = verticalBar.getIncrement ();
 	int pageIncrement = verticalBar.getPageIncrement ();
 	verticalBar.setValues(selection, 0, maxHeight, height, increment, pageIncrement);
 	verticalBar.setVisible(maxHeight > height);
 }

 /**
  * Sets the receiver's spacing. Spacing specifies the number of pixels allocated around
  * each item.
  *
  * @param spacing the spacing around each item
  *
  * @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 setSpacing (int spacing) {
 	checkWidget ();
 	if (spacing < 0) return;
 	if (spacing == this.spacing) return;
 	this.spacing = spacing;
 	int width = Math.max (0, getClientArea ().width - spacing * 2);
 	for (int i = 0; i < itemCount; i++) {
 		ExpandItem item = items[i];
 		if (item.width != width) item.setBounds (0, 0, width, item.height, false, true);
 	}
 	layoutItems (0, true);
 	redraw ();
 }

 void showItem (ExpandItem item) {
 	Control control = item.control;
 	if (control != null && !control.isDisposed ()) {
 		control.setVisible (item.expanded);
 	}
 	item.redraw ();
 	int index = indexOf (item);
 	layoutItems (index + 1, true);
 }

 void onDispose (Event event) {
 	removeListener (SWT.Dispose, listener);
 	notifyListeners (SWT.Dispose, event);
 	event.type = SWT.None;
 	/*
 	 * Usually when an item is disposed, destroyItem will change the size of the items array,
 	 * reset the bounds of all the tabs and manage the widget associated with the tab.
 	 * Since the whole folder is being disposed, this is not necessary.  For speed
 	 * the inDispose flag is used to skip over this part of the item dispose.
 	 */
 	inDispose = true;

 	for (int i = 0; i < itemCount; i++) {
 		items [i].dispose ();
 	}
 	items = null;
 	font = null;
 	foreground = null;
 	focusItem = null;
 }

 void onFocus () {
 	if (focusItem != null) focusItem.redraw ();
 }

 void onKeyDown (Event event) {
 	if (focusItem == null) return;
 	switch (event.keyCode) {
 		case 13: /* Return */
 		case 32: /* Space */
 			Event ev = new Event ();
 			ev.item = focusItem;
 			sendEvent (focusItem.expanded ? SWT.Collapse :SWT.Expand, ev);
 			focusItem.expanded = !focusItem.expanded;
 			showItem (focusItem);
 			break;
 		case SWT.ARROW_UP: {
 			int focusIndex = indexOf (focusItem);
 			if (focusIndex > 0) {
 				focusItem.redraw ();
 				focusItem = items [focusIndex - 1];
 				focusItem.redraw ();
 			}
 			break;
 		}
 		case SWT.ARROW_DOWN: {
 			int focusIndex = indexOf (focusItem);
 			if (focusIndex < itemCount - 1) {
 				focusItem.redraw ();
 				focusItem = items [focusIndex + 1];
 				focusItem.redraw ();
 			}
 			break;
 		}
 	}
 }

 void onMouseDown (Event event) {
 	if (event.button != 1) return;
 	int x = event.x;
 	int y = event.y;
 	for (int i = 0; i < itemCount; i++) {
 		ExpandItem item = items[i];
 		boolean hover = item.x <= x && x < (item.x + item.width) && item.y <= y && y < (item.y + getBandHeight ());
 		if (hover && item != focusItem) {
 			focusItem.redraw ();
 			focusItem = item;
 			focusItem.redraw ();
 			forceFocus ();
 			break;
 		}
 	}
 }

 void onMouseUp (Event event) {
 	if (event.button != 1) return;
 	if (focusItem == null) return;
 	int x = event.x;
 	int y = event.y;
 	boolean hover = focusItem.x <= x && x < (focusItem.x + focusItem.width) && focusItem.y <= y && y < (focusItem.y + getBandHeight ());
 	if (hover) {
 		Event ev = new Event ();
 		ev.item = focusItem;
 		notifyListeners (focusItem.expanded ? SWT.Collapse : SWT.Expand, ev);
 		focusItem.expanded = !focusItem.expanded;
 		showItem (focusItem);
 	}
 }

 void onPaint (Event event) {
 	boolean hasFocus = isFocusControl ();
 	for (int i = 0; i < itemCount; i++) {
 		ExpandItem item = items [i];
 		item.drawItem (event.gc, hasFocus && item == focusItem);
 	}
 }

 void onResize () {
 	Rectangle rect = getClientArea ();
 	int width = Math.max (0, rect.width - spacing * 2);
 	for (int i = 0; i < itemCount; i++) {
 		ExpandItem item = items[i];
 		item.setBounds (0, 0, width, item.height, false, true);
 	}
 	setScrollbar ();
 }

 void onScroll (Event event) {
 	ScrollBar verticalBar = getVerticalBar ();
 	if (verticalBar != null) {
 		yCurrentScroll = verticalBar.getSelection();
 		layoutItems (0, false);
 	}
 }

 void onTraverse (Event event) {
 	switch (event.detail) {
 		case SWT.TRAVERSE_TAB_NEXT:
 		case SWT.TRAVERSE_TAB_PREVIOUS:
 			event.doit = true;
 			break;
 	}
 }

 }
	/*******************************************************************************
	* Copyright (c) 2000, 2009 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.swt.widgets;

	import org.eclipse.swt.*;
	import org.eclipse.swt.graphics.*;
	import org.eclipse.swt.events.*;

	/**
	* Instances of this class support the layout of selectable
	* expand bar items.
	* <p>
	* The item children that may be added to instances of this class
	* must be of type <code>ExpandItem</code>.
	* </p><p>
	* <dl>
	* <dt><b>Styles:</b></dt>
	* <dd>V_SCROLL</dd>
	* <dt><b>Events:</b></dt>
	* <dd>Expand, Collapse</dd>
	* </dl>
	* </p><p>
	* IMPORTANT: This class is <em>not</em> intended to be subclassed.
	* </p>
	*
	* @see ExpandItem
	* @see ExpandEvent
	* @see ExpandListener
	* @see ExpandAdapter
	* @see <a href="http://www.eclipse.org/swt/snippets/#expandbar">ExpandBar snippets</a>
	* @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a>
	* @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
	*
	* @since 3.2
	* @noextend This class is not intended to be subclassed by clients.
	*/
	public class ExpandBar extends Composite {
	ExpandItem [] items;
	int itemCount;
	ExpandItem focusItem;
	int spacing;
	int yCurrentScroll;
	Font font;
	Color foreground;
	Listener listener;
	boolean inDispose;

	/**
	* 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
	* lists the style constants that are applicable to the class.
	* Style bits are also inherited from superclasses.
	* </p>
	*
	* @param parent a composite control which will be the parent of the new instance (cannot be null)
	* @param style the style of control 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#V_SCROLL
	* @see Widget#checkSubclass
	* @see Widget#getStyle
	*/
	public ExpandBar (Composite parent, int style) {
	super (parent, checkStyle (style));
	items = new ExpandItem [4];

	listener = new Listener () {
	public void handleEvent (Event event) {
	switch (event.type) {
	case SWT.Dispose: onDispose (event); break;
	case SWT.MouseDown: onMouseDown (event); break;
	case SWT.MouseUp: onMouseUp (event); break;
	case SWT.Paint: onPaint (event); break;
	case SWT.Resize: onResize (); break;
	case SWT.KeyDown: onKeyDown (event); break;
	case SWT.FocusIn: onFocus (); break;
	case SWT.FocusOut: onFocus (); break;
	case SWT.Traverse: onTraverse (event); break;
	}
	}
	};
	addListener (SWT.Dispose, listener);
	addListener (SWT.MouseDown, listener);
	addListener (SWT.MouseUp, listener);
	addListener (SWT.Paint, listener);
	addListener (SWT.Resize, listener);
	addListener (SWT.KeyDown, listener);
	addListener (SWT.FocusIn, listener);
	addListener (SWT.FocusOut, listener);
	addListener (SWT.Traverse, listener);

	ScrollBar verticalBar = getVerticalBar ();
	if (verticalBar != null) {
	verticalBar.addListener (SWT.Selection, new Listener () {
	public void handleEvent (Event event) {
	onScroll (event);
	}
	});
	}
	}

	/**
	* Adds the listener to the collection of listeners who will
	* be notified when an item in the receiver is expanded or collapsed
	* by sending it one of the messages defined in the <code>ExpandListener</code>
	* interface.
	*
	* @param listener the listener which should be notified
	*
	* @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 ExpandListener
	* @see #removeExpandListener
	*/
	public void addExpandListener (ExpandListener listener) {
	checkWidget ();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener (listener);
	addListener (SWT.Expand, typedListener);
	addListener (SWT.Collapse, typedListener);
	}

	static int checkStyle (int style) {
	return style & ~SWT.H_SCROLL;
	}

	protected void checkSubclass () {
	if (!isValidSubclass ()) error (SWT.ERROR_INVALID_SUBCLASS);
	}

	public Point computeSize (int wHint, int hHint, boolean changed) {
	checkWidget ();
	int height = 0, width = 0;
	if (wHint == SWT.DEFAULT \|\| hHint == SWT.DEFAULT) {
	if (itemCount > 0) {
	height += spacing;
	GC gc = new GC (this);
	for (int i = 0; i < itemCount; i++) {
	ExpandItem item = items [i];
	height += item.getHeaderHeight ();
	if (item.expanded) height += item.height;
	height += spacing;
	width = Math.max (width, item.getPreferredWidth (gc));
	}
	gc.dispose ();
	}
	}
	if (width == 0) width = DEFAULT_WIDTH;
	if (height == 0) height = DEFAULT_HEIGHT;
	if (wHint != SWT.DEFAULT) width = wHint;
	if (hHint != SWT.DEFAULT) height = hHint;
	Rectangle trim = computeTrim (0, 0, width, height);
	return new Point (trim.width, trim.height);
	}

	void createItem (ExpandItem item, int style, int index) {
	if (!(0 <= index && index <= itemCount)) error (SWT.ERROR_INVALID_RANGE);
	if (itemCount == items.length) {
	ExpandItem [] newItems = new ExpandItem [itemCount + 4];
	System.arraycopy (items, 0, newItems, 0, items.length);
	items = newItems;
	}
	System.arraycopy (items, index, items, index + 1, itemCount - index);
	items [index] = item;
	itemCount++;
	if (focusItem == null) focusItem = item;
	item.width = Math.max (0, getClientArea ().width - spacing * 2);
	layoutItems (index, true);
	}

	void destroyItem (ExpandItem item) {
	if (inDispose) return;
	int index = 0;
	while (index < itemCount) {
	if (items [index] == item) break;
	index++;
	}
	if (index == itemCount) return;
	if (item == focusItem) {
	int focusIndex = index > 0 ? index - 1 : 1;
	if (focusIndex < itemCount) {
	focusItem = items [focusIndex];
	focusItem.redraw ();
	} else {
	focusItem = null;
	}
	}
	System.arraycopy (items, index + 1, items, index, --itemCount - index);
	items [itemCount] = null;
	item.redraw ();
	layoutItems (index, true);
	}

	int getBandHeight () {
	if (font == null) return ExpandItem.CHEVRON_SIZE;
	GC gc = new GC (this);
	FontMetrics metrics = gc.getFontMetrics ();
	gc.dispose ();
	return Math.max (ExpandItem.CHEVRON_SIZE, metrics.getHeight ());
	}

	public Color getForeground () {
	checkWidget ();
	if (foreground == null) {
	Display display = getDisplay ();
	return display.getSystemColor (SWT.COLOR_TITLE_FOREGROUND);
	}
	return foreground;
	}

	/**
	* Returns the item at the given, zero-relative index in the
	* receiver. Throws an exception if the index is out of range.
	*
	* @param index the index of the item to return
	* @return the item at the given index
	*
	* @exception IllegalArgumentException <ul>
	* <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list minus 1 (inclusive)</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 ExpandItem getItem (int index) {
	checkWidget ();
	if (!(0 <= index && index < itemCount)) error (SWT.ERROR_INVALID_RANGE);
	return items [index];
	}

	/**
	* Returns the number of items contained in the receiver.
	*
	* @return the number of items
	*
	* @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 getItemCount () {
	checkWidget ();
	return itemCount;
	}

	/**
	* Returns an array of <code>ExpandItem</code>s which are the items
	* in the receiver.
	* <p>
	* Note: This is not the actual structure used by the receiver
	* to maintain its list of items, so modifying the array will
	* not affect the receiver.
	* </p>
	*
	* @return the items in the receiver
	*
	* @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 ExpandItem [] getItems () {
	checkWidget ();
	ExpandItem [] result = new ExpandItem [itemCount];
	System.arraycopy (items, 0, result, 0, itemCount);
	return result;
	}

	/**
	* Returns the receiver's spacing.
	*
	* @return the spacing
	*
	* @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 getSpacing () {
	checkWidget ();
	return spacing;
	}

	/**
	* Searches the receiver's list starting at the first item
	* (index 0) until an item is found that is equal to the
	* argument, and returns the index of that item. If no item
	* is found, returns -1.
	*
	* @param item the search item
	* @return the index of the item
	*
	* @exception IllegalArgumentException <ul>
	* <li>ERROR_NULL_ARGUMENT - if the item is null</li>
	* <li>ERROR_INVALID_ARGUMENT - if the item has been disposed</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 int indexOf (ExpandItem item) {
	checkWidget ();
	if (item == null) error (SWT.ERROR_NULL_ARGUMENT);
	for (int i = 0; i < itemCount; i++) {
	if (items [i] == item) return i;
	}
	return -1;
	}

	void layoutItems (int index, boolean setScrollbar) {
	if (index < itemCount) {
	int y = spacing - yCurrentScroll;
	for (int i = 0; i < index; i++) {
	ExpandItem item = items [i];
	if (item.expanded) y += item.height;
	y += item.getHeaderHeight() + spacing;
	}
	for (int i = index; i < itemCount; i++) {
	ExpandItem item = items [i];
	item.setBounds (spacing, y, 0, 0, true, false);
	if (item.expanded) y += item.height;
	y += item.getHeaderHeight() + spacing;
	}
	}
	if (setScrollbar) setScrollbar ();
	}

	/**
	* Removes the listener from the collection of listeners who will
	* be notified when items in the receiver are expanded or collapsed.
	*
	* @param listener the listener which should no longer be notified
	*
	* @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 ExpandListener
	* @see #addExpandListener
	*/
	public void removeExpandListener (ExpandListener listener) {
	checkWidget ();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Expand, listener);
	eventTable.unhook (SWT.Collapse, listener);
	}

	void reskinChildren (int flags) {
	if (items != null) {
	for (int i=0; i<items.length; i++) {
	ExpandItem item = items [i];
	if (item != null ) item.reskin (flags);
	}
	}
	super.reskinChildren (flags);
	}

	public void setFont(Font font) {
	super.setFont (font);
	this.font = font;
	layoutItems (0, true);
	}

	public void setForeground (Color color) {
	super.setForeground (color);
	foreground = color;
	}

	void setScrollbar () {
	if (itemCount == 0) return;
	ScrollBar verticalBar = getVerticalBar ();
	if (verticalBar == null) return;
	int height = getClientArea ().height;
	ExpandItem item = items [itemCount - 1];
	int maxHeight = item.y + getBandHeight () + spacing;
	if (item.expanded) maxHeight += item.height;

	//claim bottom free space
	if (yCurrentScroll > 0 && height > maxHeight) {
	yCurrentScroll = Math.max (0, yCurrentScroll + maxHeight - height);
	layoutItems (0, false);
	}
	maxHeight += yCurrentScroll;

	int selection = Math.min (yCurrentScroll, maxHeight);
	int increment = verticalBar.getIncrement ();
	int pageIncrement = verticalBar.getPageIncrement ();
	verticalBar.setValues(selection, 0, maxHeight, height, increment, pageIncrement);
	verticalBar.setVisible(maxHeight > height);
	}

	/**
	* Sets the receiver's spacing. Spacing specifies the number of pixels allocated around
	* each item.
	*
	* @param spacing the spacing around each item
	*
	* @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 setSpacing (int spacing) {
	checkWidget ();
	if (spacing < 0) return;
	if (spacing == this.spacing) return;
	this.spacing = spacing;
	int width = Math.max (0, getClientArea ().width - spacing * 2);
	for (int i = 0; i < itemCount; i++) {
	ExpandItem item = items[i];
	if (item.width != width) item.setBounds (0, 0, width, item.height, false, true);
	}
	layoutItems (0, true);
	redraw ();
	}

	void showItem (ExpandItem item) {
	Control control = item.control;
	if (control != null && !control.isDisposed ()) {
	control.setVisible (item.expanded);
	}
	item.redraw ();
	int index = indexOf (item);
	layoutItems (index + 1, true);
	}

	void onDispose (Event event) {
	removeListener (SWT.Dispose, listener);
	notifyListeners (SWT.Dispose, event);
	event.type = SWT.None;
	/*
	* Usually when an item is disposed, destroyItem will change the size of the items array,
	* reset the bounds of all the tabs and manage the widget associated with the tab.
	* Since the whole folder is being disposed, this is not necessary. For speed
	* the inDispose flag is used to skip over this part of the item dispose.
	*/
	inDispose = true;

	for (int i = 0; i < itemCount; i++) {
	items [i].dispose ();
	}
	items = null;
	font = null;
	foreground = null;
	focusItem = null;
	}

	void onFocus () {
	if (focusItem != null) focusItem.redraw ();
	}

	void onKeyDown (Event event) {
	if (focusItem == null) return;
	switch (event.keyCode) {
	case 13: /* Return */
	case 32: /* Space */
	Event ev = new Event ();
	ev.item = focusItem;
	sendEvent (focusItem.expanded ? SWT.Collapse :SWT.Expand, ev);
	focusItem.expanded = !focusItem.expanded;
	showItem (focusItem);
	break;
	case SWT.ARROW_UP: {
	int focusIndex = indexOf (focusItem);
	if (focusIndex > 0) {
	focusItem.redraw ();
	focusItem = items [focusIndex - 1];
	focusItem.redraw ();
	}
	break;
	}
	case SWT.ARROW_DOWN: {
	int focusIndex = indexOf (focusItem);
	if (focusIndex < itemCount - 1) {
	focusItem.redraw ();
	focusItem = items [focusIndex + 1];
	focusItem.redraw ();
	}
	break;
	}
	}
	}

	void onMouseDown (Event event) {
	if (event.button != 1) return;
	int x = event.x;
	int y = event.y;
	for (int i = 0; i < itemCount; i++) {
	ExpandItem item = items[i];
	boolean hover = item.x <= x && x < (item.x + item.width) && item.y <= y && y < (item.y + getBandHeight ());
	if (hover && item != focusItem) {
	focusItem.redraw ();
	focusItem = item;
	focusItem.redraw ();
	forceFocus ();
	break;
	}
	}
	}

	void onMouseUp (Event event) {
	if (event.button != 1) return;
	if (focusItem == null) return;
	int x = event.x;
	int y = event.y;
	boolean hover = focusItem.x <= x && x < (focusItem.x + focusItem.width) && focusItem.y <= y && y < (focusItem.y + getBandHeight ());
	if (hover) {
	Event ev = new Event ();
	ev.item = focusItem;
	notifyListeners (focusItem.expanded ? SWT.Collapse : SWT.Expand, ev);
	focusItem.expanded = !focusItem.expanded;
	showItem (focusItem);
	}
	}

	void onPaint (Event event) {
	boolean hasFocus = isFocusControl ();
	for (int i = 0; i < itemCount; i++) {
	ExpandItem item = items [i];
	item.drawItem (event.gc, hasFocus && item == focusItem);
	}
	}

	void onResize () {
	Rectangle rect = getClientArea ();
	int width = Math.max (0, rect.width - spacing * 2);
	for (int i = 0; i < itemCount; i++) {
	ExpandItem item = items[i];
	item.setBounds (0, 0, width, item.height, false, true);
	}
	setScrollbar ();
	}

	void onScroll (Event event) {
	ScrollBar verticalBar = getVerticalBar ();
	if (verticalBar != null) {
	yCurrentScroll = verticalBar.getSelection();
	layoutItems (0, false);
	}
	}

	void onTraverse (Event event) {
	switch (event.detail) {
	case SWT.TRAVERSE_TAB_NEXT:
	case SWT.TRAVERSE_TAB_PREVIOUS:
	event.doit = true;
	break;
	}
	}

	}