bundles/org.eclipse.swt/Eclipse SWT/wpf/org/eclipse/swt/widgets/List.java

/*******************************************************************************
 * Copyright (c) 2000, 2008 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.internal.wpf.*;
import org.eclipse.swt.*;
import org.eclipse.swt.events.*;

/** 
 * Instances of this class represent a selectable user interface
 * object that displays a list of strings and issues notification
 * when a string is selected.  A list may be single or multi select.
 * <p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>SINGLE, MULTI</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection, DefaultSelection</dd>
 * </dl>
 * <p>
 * Note: Only one of SINGLE and MULTI may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see <a href="http://www.eclipse.org/swt/snippets/#list">List 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>
 * @noextend This class is not intended to be subclassed by clients.
 */

public class List extends Scrollable {
	boolean ignoreSelection;

/**
 * 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#SINGLE
 * @see SWT#MULTI
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public List (Composite parent, int style) {
	super (parent, checkStyle (style));
}

/**
 * Adds the argument to the end of the receiver's list.
 *
 * @param string the new item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string 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 #add(String,int)
 */
public void add (String string) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	int item = OS.gcnew_ListBoxItem ();
	int strPtr = createDotNetString (string, false);
	OS.ContentControl_Content (item, strPtr);
	OS.GCHandle_Free (strPtr);
	int items = OS.ItemsControl_Items (handle);
	OS.ItemCollection_Add (items, item);
	OS.GCHandle_Free (items);
	OS.GCHandle_Free (item);
}

/**
 * Adds the argument to the receiver's list at the given
 * zero-relative index.
 * <p>
 * Note: To add an item at the end of the list, use the
 * result of calling <code>getItemCount()</code> as the
 * index or use <code>add(String)</code>.
 * </p>
 *
 * @param string the new item
 * @param index the index for the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list (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>
 *
 * @see #add(String)
 */
public void add (String string, int index) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (index < 0 || index > getItemCount ()) error (SWT.ERROR_INVALID_RANGE);
	int item = OS.gcnew_ListBoxItem ();
	int strPtr = createDotNetString (string, false);
	OS.ContentControl_Content (item, strPtr);
	OS.GCHandle_Free (strPtr);
	int items = OS.ItemsControl_Items (handle);
	OS.ItemCollection_Insert (items, index, item);
	OS.GCHandle_Free (items);
	OS.GCHandle_Free (item);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the user changes the receiver's selection, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * <code>widgetSelected</code> is called when the selection changes.
 * <code>widgetDefaultSelected</code> is typically called when an item is double-clicked.
 * </p>
 *
 * @param listener the listener which should be notified when the user changes the receiver's selection
 *
 * @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 SelectionListener
 * @see #removeSelectionListener
 * @see SelectionEvent
 */
public void addSelectionListener(SelectionListener listener) {
	checkWidget ();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener (listener);
	addListener (SWT.Selection,typedListener);
	addListener (SWT.DefaultSelection,typedListener);
}

static int checkStyle (int style) {
	return checkBits (style, SWT.SINGLE, SWT.MULTI, 0, 0, 0, 0);
}

void createHandle () {
	handle = OS.gcnew_ListBox ();
	if (handle == 0) error (SWT.ERROR_NO_HANDLES);
	OS.Selector_IsSynchronizedWithCurrentItem (handle, true);
	if ((style & SWT.MULTI) != 0) OS.ListBox_SelectionMode (handle, OS.SelectionMode_Extended);
}

/**
 * Deselects the items at the given zero-relative indices in the receiver.
 * If the item at the given zero-relative index in the receiver 
 * is selected, it is deselected.  If the item at the index
 * was not selected, it remains deselected. Indices that are out
 * of range and duplicate indices are ignored.
 *
 * @param indices the array of indices for the items to deselect
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the set of indices 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 deselect (int [] indices) {
	checkWidget ();
	if (indices == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (indices.length == 0) return;
	int count = getItemCount ();
	int items = OS.ItemsControl_Items (handle);
	ignoreSelection = true;
	for (int i = 0; i < indices.length; i++) {
		int index = indices [i];
		if (0 <= index && index < count) {
			int item = OS.ItemCollection_GetItemAt (items, index);
			OS.ListBoxItem_IsSelected (item, false);
			OS.GCHandle_Free (item);
		}
	}
	ignoreSelection = false;
	OS.GCHandle_Free (items);
}

/**
 * Deselects the item at the given zero-relative index in the receiver.
 * If the item at the index was already deselected, it remains
 * deselected. Indices that are out of range are ignored.
 *
 * @param index the index of the item to deselect
 *
 * @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 deselect (int index) {
	checkWidget ();
	if (index == -1) return;
	if (0 <= index && index < getItemCount ()) {
		int items = OS.ItemsControl_Items (handle);
		int item = OS.ItemCollection_GetItemAt (items, index);
		OS.GCHandle_Free (items);
		ignoreSelection = true;
		OS.ListBoxItem_IsSelected (item, false);
		ignoreSelection = false;
		OS.GCHandle_Free (item);
	}
}

/**
 * Deselects the items at the given zero-relative indices in the receiver.
 * If the item at the given zero-relative index in the receiver 
 * is selected, it is deselected.  If the item at the index
 * was not selected, it remains deselected.  The range of the
 * indices is inclusive. Indices that are out of range are ignored.
 *
 * @param start the start index of the items to deselect
 * @param end the end index of the items to deselect
 *
 * @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 deselect (int start, int end) {
	checkWidget ();
	if (start > end) return;
	int count = getItemCount ();
	int items = OS.ItemsControl_Items (handle);
	ignoreSelection = true;
	for (int i = end; i >= start; i--) {
		if (0 <= i && i < count) {
			int item = OS.ItemCollection_GetItemAt (items, i);
			OS.ListBoxItem_IsSelected (item, false);
			OS.GCHandle_Free (item);
		}
	}
	ignoreSelection = false;
	OS.GCHandle_Free (items);
}

/**
 * Deselects all selected 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 void deselectAll () {
	checkWidget ();
	ignoreSelection = true;
	OS.ListBox_UnselectAll (handle);
	ignoreSelection = false;
}

/**
 * Returns the zero-relative index of the item which currently
 * has the focus in the receiver, or -1 if no item has focus.
 *
 * @return the index of the selected 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 int getFocusIndex () {
	checkWidget ();
	int items = OS.ItemsControl_Items (handle);
	int index = OS.ItemCollection_CurrentPosition (items);
	OS.GCHandle_Free (items);
	return index;	
}

/**
 * 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 String getItem (int index) {
	checkWidget ();
	int count = getItemCount ();
	if (index < 0 || index >= count) error (SWT.ERROR_INVALID_RANGE);
	int items = OS.ItemsControl_Items (handle);
	int item = OS.ItemCollection_GetItemAt (items, index);
	int content = OS.ContentControl_Content (item);
	String string = createJavaString (content);
	OS.GCHandle_Free (item);
	OS.GCHandle_Free (items);
	OS.GCHandle_Free (content);
	return string;
}

/**
 * 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 ();	
	int items = OS.ItemsControl_Items (handle);
	int count = OS.ItemCollection_Count (items);
	OS.GCHandle_Free (items);
	return count;
}

/**
 * Returns the height of the area which would be used to
 * display <em>one</em> of the items in the list.
 *
 * @return the height of one 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 int getItemHeight () {
	checkWidget ();
	//FIXME what is the default size?
	if (!OS.ItemsControl_HasItems (handle)) return 16;
	int items = OS.ItemsControl_Items (handle);
	int item = OS.ItemCollection_GetItemAt (items, 0);
	double height = OS.FrameworkElement_ActualHeight (item);
	OS.GCHandle_Free (item);
	OS.GCHandle_Free (items);
	return height != 0 ? (int) height : 16;
}

/**
 * Returns a (possibly empty) array of <code>String</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's list
 *
 * @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 String [] getItems () {
	checkWidget ();
	int count = getItemCount ();
	String [] result = new String [count];
	for (int i=0; i<count; i++) result [i] = getItem (i);
	return result;
}

/**
 * Returns an array of <code>String</code>s that are currently
 * selected in the receiver.  The order of the items is unspecified.
 * An empty array indicates that no items are selected.
 * <p>
 * Note: This is not the actual structure used by the receiver
 * to maintain its selection, so modifying the array will
 * not affect the receiver. 
 * </p>
 * @return an array representing the selection
 *
 * @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 String [] getSelection () {
	checkWidget ();
	int [] indices = getSelectionIndices ();
	String [] result = new String [indices.length];
	for (int i=0; i<indices.length; i++) {
		result [i] = getItem (indices [i]);
	}
	return result;
}

/**
 * Returns the number of selected items contained in the receiver.
 *
 * @return the number of selected 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 getSelectionCount () {
	checkWidget ();
	int selectedItems = OS.ListBox_SelectedItems (handle);
	int result = OS.ICollection_Count (selectedItems);
	OS.GCHandle_Free (selectedItems);
	return result;
}

/**
 * Returns the zero-relative index of the item which is currently
 * selected in the receiver, or -1 if no item is selected.
 *
 * @return the index of the selected item or -1
 *
 * @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 getSelectionIndex () {
	checkWidget ();
	return OS.Selector_SelectedIndex (handle);
}

/**
 * Returns the zero-relative indices of the items which are currently
 * selected in the receiver.  The order of the indices is unspecified.
 * The array is empty if no items are selected.
 * <p>
 * Note: This is not the actual structure used by the receiver
 * to maintain its selection, so modifying the array will
 * not affect the receiver. 
 * </p>
 * @return the array of indices of the selected 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 [] getSelectionIndices () {
	checkWidget ();
	int items = OS.ItemsControl_Items (handle);
	int list = OS.ListBox_SelectedItems (handle);
	int enumerator = OS.IList_GetEnumerator (list);
	int count = OS.ICollection_Count (list);
	int [] indices = new int [count];
	int index = 0;
    while (OS.IEnumerator_MoveNext (enumerator)) {
    	int item = OS.IEnumerator_Current (enumerator);
		indices [index++] = OS.ItemCollection_IndexOf (items, item);
		OS.GCHandle_Free (item);
	}
    OS.GCHandle_Free (enumerator);
	OS.GCHandle_Free (list);
	OS.GCHandle_Free (items);
	sortAscending (indices);
	return indices;
}

/**
 * Returns the zero-relative index of the item which is currently
 * at the top of the receiver. This index can change when items are
 * scrolled or new items are added or removed.
 *
 * @return the index of the top 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 int getTopIndex () {
	checkWidget ();
	int topIndex = 0;
	if (OS.ItemsControl_HasItems (handle)) {
		int items = OS.ItemsControl_Items (handle);
		int item = OS.ItemCollection_GetItemAt (items, 0);
		OS.GCHandle_Free (items);
		int virtualizingStackPanel = OS.VisualTreeHelper_GetParent (item);
		OS.GCHandle_Free (item);
		if (virtualizingStackPanel != 0) {
			topIndex = (int) OS.VirtualizingStackPanel_VerticalOffset (virtualizingStackPanel);
			OS.GCHandle_Free (virtualizingStackPanel); 
		}
	}
	return topIndex;
}

void HandleMouseDoubleClick (int sender, int e) {
	if (!checkEvent (e)) return;
	postEvent (SWT.DefaultSelection);
}

void HandleSelectionChanged (int sender, int e) {
	if (!checkEvent (e)) return;
	if (!ignoreSelection) postEvent(SWT.Selection);
}

void HandlePreviewKeyDown (int sender, int e) {
	super.HandlePreviewKeyDown (sender, e);
	if (!checkEvent (e)) return;
	int key = OS.KeyEventArgs_Key (e);
	if (key == OS.Key_Return) {
		postEvent (SWT.DefaultSelection);
	}
}

void hookEvents () {
	super.hookEvents ();
	int handler = OS.gcnew_SelectionChangedEventHandler (jniRef, "HandleSelectionChanged");
	OS.Selector_SelectionChanged (handle, handler);
	OS.GCHandle_Free (handler);
	handler = OS.gcnew_MouseButtonEventHandler (jniRef, "HandleMouseDoubleClick");
	OS.Control_MouseDoubleClick (handle, handler);
	OS.GCHandle_Free (handler);
}

/**
 * Gets the index of an item.
 * <p>
 * The list is searched starting at 0 until an
 * item is found that is equal to the search item.
 * If no item is found, -1 is returned.  Indexing
 * is zero based.
 *
 * @param string the search item
 * @return the index of the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string 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 int indexOf (String string) {
	return indexOf (string, 0);
}

/**
 * Searches the receiver's list starting at the given, 
 * zero-relative index until an item is found that is equal
 * to the argument, and returns the index of that item. If
 * no item is found or the starting index is out of range,
 * returns -1.
 *
 * @param string the search item
 * @param start the zero-relative index at which to start the search
 * @return the index of the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string 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 int indexOf (String string, int start) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	int count = getItemCount ();
	if (start >= count) return -1;
	start = Math.max (start, 0);
	int strPtr = createDotNetString (string, false);
	int items = OS.ItemsControl_Items (handle);
	int index = -1;
	while (start < count && index == -1) {
		int item = OS.ItemCollection_GetItemAt (items, start);
		int content = OS.ContentControl_Content (item);
		OS.GCHandle_Free (item);
		if (content != 0) {
			if (OS.Object_Equals (content, strPtr)) index = start;
			OS.GCHandle_Free (content);
		}  
		start++;
	}
	OS.GCHandle_Free (strPtr);
	OS.GCHandle_Free (items);
	return index;
}

/**
 * Returns <code>true</code> if the item is selected,
 * and <code>false</code> otherwise.  Indices out of
 * range are ignored.
 *
 * @param index the index of the item
 * @return the selection state of the item at the index
 *
 * @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 boolean isSelected (int index) {
	checkWidget ();
	boolean selected = false;
	if (index >= 0 && index < getItemCount ()) {
		int items = OS.ItemsControl_Items (handle);
		int item = OS.ItemCollection_GetItemAt (items, index);
		selected = OS.ListBoxItem_IsSelected (item);
		OS.GCHandle_Free (items);
		OS.GCHandle_Free (item);
	}
	return selected;
}

/**
 * Removes the items from the receiver at the given
 * zero-relative indices.
 *
 * @param indices the array of indices of the items
 *
 * @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>
 *    <li>ERROR_NULL_ARGUMENT - if the indices array 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 remove (int [] indices) {
	checkWidget ();
	if (indices == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (indices.length == 0) return;
	int [] newIndices = new int [indices.length];
	System.arraycopy (indices, 0, newIndices, 0, indices.length);
	sort (newIndices);
	int start = newIndices [newIndices.length - 1], end = newIndices [0];
	int count = getItemCount ();
	if (!(0 <= start && start <= end && end < count)) {
		error (SWT.ERROR_INVALID_RANGE);
	}
	int items = OS.ItemsControl_Items (handle);
	for (int i = newIndices.length-1; i >= 0; i--) {
		OS.ItemCollection_RemoveAt (items, indices [i]);
	}
	OS.GCHandle_Free (items);
}

/**
 * Removes the item from the receiver at the given
 * zero-relative index.
 *
 * @param index the index for the item
 *
 * @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 void remove (int index) {
	checkWidget ();
	if (index < 0 || index >= getItemCount ()) error (SWT.ERROR_INVALID_RANGE);
	int items = OS.ItemsControl_Items (handle);
	OS.ItemCollection_RemoveAt (items, index);
	OS.GCHandle_Free (items);
}

/**
 * Removes the items from the receiver which are
 * between the given zero-relative start and end 
 * indices (inclusive).
 *
 * @param start the start of the range
 * @param end the end of the range
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_RANGE - if either the start or end are 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 void remove (int start, int end) {
	checkWidget ();
	if (start > end) return;
	int count = getItemCount ();
	if (!(0 <= start && start <= end && end < count)) error (SWT.ERROR_INVALID_RANGE);
	if (start == 0 && end == count - 1) {
		removeAll ();
		return;
	} 
	int items = OS.ItemsControl_Items (handle);
	for (int i = end; i >= start; i--) {
		OS.ItemCollection_RemoveAt (items, i);
	}
	OS.GCHandle_Free (items);
}

/**
 * Searches the receiver's list starting at the first item
 * until an item is found that is equal to the argument, 
 * and removes that item from the list.
 *
 * @param string the item to remove
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the string is not found in the list</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 remove (String string) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	int index = indexOf (string, 0);
	if (index == -1) error (SWT.ERROR_INVALID_ARGUMENT);
	remove (index);
}

/**
 * Removes all of the items from the receiver.
 * <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>
 */
public void removeAll () {
	checkWidget ();
	int items = OS.ItemsControl_Items (handle);
	ignoreSelection = true;
	OS.ItemCollection_Clear (items);
	ignoreSelection = false;
	OS.GCHandle_Free (items);
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when the user changes the receiver's selection.
 *
 * @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 SelectionListener
 * @see #addSelectionListener
 */
public void removeSelectionListener(SelectionListener listener) {
	checkWidget ();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Selection, listener);
	eventTable.unhook (SWT.DefaultSelection,listener);	
}

/**
 * Selects the items at the given zero-relative indices in the receiver.
 * The current selection is not cleared before the new items are selected.
 * <p>
 * If the item at a given index is not selected, it is selected.
 * If the item at a given index was already selected, it remains selected.
 * Indices that are out of range and duplicate indices are ignored.
 * If the receiver is single-select and multiple indices are specified,
 * then all indices are ignored.
 *
 * @param indices the array of indices for the items to select
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the array of indices 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 List#setSelection(int[])
 */
public void select (int [] indices) {
	checkWidget ();
	if (indices == null) error (SWT.ERROR_NULL_ARGUMENT);
	int length = indices.length;
	if (length == 0 || ((style & SWT.SINGLE) != 0 && length > 1)) return;
	select (indices, false);
}

void select (int [] indices, boolean scroll) {
	int i = 0;
	while (i < indices.length) {
		int index = indices [i];
		if (index != -1) {
			select (index, false);
		}
		i++;
	}
	if (scroll) showSelection ();
}

/**
 * Selects the item at the given zero-relative index in the receiver's 
 * list.  If the item at the index was already selected, it remains
 * selected. Indices that are out of range are ignored.
 *
 * @param index the index of the item to select
 *
 * @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 select (int index) {
	checkWidget ();
	select (index, false);
}

void select (int index, boolean scroll) {
	if (index < 0) return;
	int count = getItemCount ();
	if (index >= count) return;
	int items = OS.ItemsControl_Items (handle);
	int item = OS.ItemCollection_GetItemAt (items, index);
	OS.GCHandle_Free (items);
	ignoreSelection = true;
	OS.ListBoxItem_IsSelected (item, true);
	ignoreSelection = false;
	if (scroll) OS.FrameworkElement_BringIntoView (item);
	OS.GCHandle_Free (item);
}

/**
 * Selects the items in the range specified by the given zero-relative
 * indices in the receiver. The range of indices is inclusive.
 * The current selection is not cleared before the new items are selected.
 * <p>
 * If an item in the given range is not selected, it is selected.
 * If an item in the given range was already selected, it remains selected.
 * Indices that are out of range are ignored and no items will be selected
 * if start is greater than end.
 * If the receiver is single-select and there is more than one item in the
 * given range, then all indices are ignored.
 *
 * @param start the start of the range
 * @param end the end of the range
 *
 * @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 List#setSelection(int,int)
 */
public void select (int start, int end) {
	checkWidget ();
	if (end < 0 || start > end || ((style & SWT.SINGLE) != 0 && start != end)) return;
	int count = getItemCount ();
	if (count == 0 || start >= count) return;
	start = Math.max (0, start);
	end = Math.min (end, count - 1);
	ignoreSelection = true;
	if ((style & SWT.SINGLE) != 0) {
		select (start, false);
	} else {
		select (start, end, false);
	}
	ignoreSelection = false;
}

void select (int start, int end, boolean scroll) {
	int items = OS.ItemsControl_Items (handle);
	ignoreSelection = true;
	for (int i = start; i<=end; i++) {
		int item = OS.ItemCollection_GetItemAt (items, i);
		OS.ListBoxItem_IsSelected (item, true);
		OS.GCHandle_Free (item);
	}
	ignoreSelection = false;
	OS.GCHandle_Free (items);
	if (scroll) showSelection ();
}
	
/**
 * Selects all of the items in the receiver.
 * <p>
 * If the receiver is single-select, do nothing.
 *
 * @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 selectAll () {
	checkWidget ();
	if ((style & SWT.SINGLE) != 0) return;
	ignoreSelection = true;
	OS.ListBox_SelectAll (handle);
	ignoreSelection = false;
}

/**
 * Sets the text of the item in the receiver's list at the given
 * zero-relative index to the string argument.
 *
 * @param index the index for the item
 * @param string the new text for the item
 *
 * @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>
 *    <li>ERROR_NULL_ARGUMENT - if the string 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 setItem (int index, String string) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	int topIndex = getTopIndex ();
	boolean isSelected = isSelected (index);
	remove (index);
	add (string, index);
	if (isSelected) select (index, false);
	setTopIndex (topIndex);
}

/**
 * Sets the receiver's items to be the given array of items.
 *
 * @param items the array of items
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the items array is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if an item in the items array 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 setItems (String [] items) {
	checkWidget ();
	if (items == null) error (SWT.ERROR_NULL_ARGUMENT);
	for (int i=0; i<items.length; i++) {
		if (items [i] == null) error (SWT.ERROR_INVALID_ARGUMENT);
	}
	int itemCollection = OS.ItemsControl_Items (handle);
	ignoreSelection = true;
	OS.ItemCollection_Clear (itemCollection);
	for (int i = 0; i < items.length; i++) {
		String string = items [i];
		int item = OS.gcnew_ListBoxItem ();
		int strPtr = createDotNetString (string, false);
		OS.ContentControl_Content (item, strPtr);
		OS.GCHandle_Free (strPtr);
		OS.ItemCollection_Add (itemCollection, item);
		OS.GCHandle_Free (item);
	}
	ignoreSelection = false;
	OS.GCHandle_Free (itemCollection);
}

/**
 * Selects the items at the given zero-relative indices in the receiver.
 * The current selection is cleared before the new items are selected.
 * <p>
 * Indices that are out of range and duplicate indices are ignored.
 * If the receiver is single-select and multiple indices are specified,
 * then all indices are ignored.
 *
 * @param indices the indices of the items to select
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the array of indices 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 List#deselectAll()
 * @see List#select(int[])
 */
public void setSelection (int [] indices) {
	checkWidget ();
	if (indices == null) error (SWT.ERROR_NULL_ARGUMENT);
	deselectAll ();
	int length = indices.length;
	if (length == 0 || ((style & SWT.SINGLE) != 0 && length > 1)) return;
	select (indices, true);
}

/**
 * Sets the receiver's selection to be the given array of items.
 * The current selection is cleared before the new items are selected.
 * <p>
 * Items that are not in the receiver are ignored.
 * If the receiver is single-select and multiple items are specified,
 * then all items are ignored.
 *
 * @param items the array of items
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the array of items 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 List#deselectAll()
 * @see List#select(int[])
 * @see List#setSelection(int[])
 */
public void setSelection (String [] items) {
	checkWidget ();
	if (items == null) error (SWT.ERROR_NULL_ARGUMENT);
	deselectAll ();
	int length = items.length;
	if (length == 0 || ((style & SWT.SINGLE) != 0 && length > 1)) return;
	for (int i=length-1; i>=0; --i) {
		String string = items [i];
		int index = 0;
		if (string != null) {
			while ((index = indexOf (string, index)) != -1) {
				select (index, false);
				if ((style & SWT.SINGLE) != 0 && isSelected (index)) {
					showSelection ();
					return;
				}
				index++;
			}
		}
	}
}

/**
 * Selects the item at the given zero-relative index in the receiver. 
 * If the item at the index was already selected, it remains selected.
 * The current selection is first cleared, then the new item is selected.
 * Indices that are out of range are ignored.
 *
 * @param index the index of the item to select
 *
 * @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 List#deselectAll()
 * @see List#select(int)
 */
public void setSelection (int index) {
	checkWidget ();
	deselectAll ();
	select (index, true);
}

/**
 * Selects the items in the range specified by the given zero-relative
 * indices in the receiver. The range of indices is inclusive.
 * The current selection is cleared before the new items are selected.
 * <p>
 * Indices that are out of range are ignored and no items will be selected
 * if start is greater than end.
 * If the receiver is single-select and there is more than one item in the
 * given range, then all indices are ignored.
 *
 * @param start the start index of the items to select
 * @param end the end index of the items to select
 *
 * @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 List#deselectAll()
 * @see List#select(int,int)
 */
public void setSelection (int start, int end) {
	checkWidget ();
	deselectAll ();
	if (end < 0 || start > end || ((style & SWT.SINGLE) != 0 && start != end)) return;
	int count = getItemCount ();
	if (count == 0 || start >= count) return;
	start = Math.max (0, start);
	end = Math.min (end, count - 1);
	if ((style & SWT.SINGLE) != 0) {
		select (start, true);
	} else {
		select (start, end, true);
	}
}

/**
 * Sets the zero-relative index of the item which is currently
 * at the top of the receiver. This index can change when items
 * are scrolled or new items are added and removed.
 *
 * @param index the index of the top 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 setTopIndex (int index) {
	checkWidget ();
	//FIXME: VirtualizingStackPanel.VerticalIndex cannot be set.
}

/**
 * Shows the selection.  If the selection is already showing in the receiver,
 * this method simply returns.  Otherwise, the items are scrolled until
 * the selection is visible.
 *
 * @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 showSelection () {
	//TODO: does this scroll the first selected item into view if 
	// part of the selection is visible already???
	checkWidget ();
	int items = OS.ItemsControl_Items (handle);
	int selectedItems = OS.ListBox_SelectedItems (handle);
	int enumerator = OS.IList_GetEnumerator (selectedItems);
	if (OS.IEnumerator_MoveNext (enumerator)) {
		int item = OS.IEnumerator_Current (enumerator);
	    OS.ListBox_ScrollIntoView (handle, item);
		OS.GCHandle_Free (item);
	}
    OS.GCHandle_Free (enumerator);
	OS.GCHandle_Free (selectedItems);
	OS.GCHandle_Free (items);
}
}