/*******************************************************************************
 * Copyright (c) 2000, 2007 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
 *     Tom Seidel      - enhancements for image-handling
 *     Michael Edwards - further enhancements to support image AND text in 
 *                       collapsed state of combo
 *******************************************************************************/
package com.axelerator.studio.rc.util.ui;

import java.util.Arrays;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.accessibility.ACC;
import org.eclipse.swt.accessibility.AccessibleAdapter;
import org.eclipse.swt.accessibility.AccessibleControlAdapter;
import org.eclipse.swt.accessibility.AccessibleControlEvent;
import org.eclipse.swt.accessibility.AccessibleEvent;
import org.eclipse.swt.accessibility.AccessibleTextAdapter;
import org.eclipse.swt.accessibility.AccessibleTextEvent;
import org.eclipse.swt.events.ModifyListener;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.events.VerifyListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.List;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableItem;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.TypedListener;
import org.eclipse.swt.widgets.Widget;
import org.eclipse.ui.forms.widgets.TableWrapData;
import org.eclipse.ui.forms.widgets.TableWrapLayout;

/**
 * Instances of this class are controls that allow the user
 * to choose an item from a list of items, or optionally 
 * enter a new value by typing it into an editable text
 * field. Often, <code>Combo</code>s are used in the same place
 * where a single selection <code>List</code> widget could
 * be used but space is limited. A <code>Combo</code> takes
 * less space than a <code>List</code> widget and shows
 * similar information.
 * <p>
 * Note: Since <code>Combo</code>s can contain both a list
 * and an editable text field, it is possible to confuse methods
 * which access one versus the other (compare for example,
 * <code>clearSelection()</code> and <code>deselectAll()</code>).
 * The API documentation is careful to indicate either "the
 * receiver's list" or the "the receiver's text field" to 
 * distinguish between the two cases.
 * </p><p>
 * Note that although this class is a subclass of <code>Composite</code>,
 * it does not make sense to add children to it, or set a layout on it.
 * </p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>DROP_DOWN, READ_ONLY, SIMPLE</dd>
 * <dt><b>Events:</b></dt>
 * <dd>DefaultSelection, Modify, Selection, Verify</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles DROP_DOWN and SIMPLE may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see List
 */

public class ImageCombo extends Composite {
    boolean noSelection, ignoreDefaultSelection, ignoreCharacter, ignoreModify;
    int cbtHook, scrollWidth, visibleCount = 5;

    private Composite comboComposite;
    private Label imageLabel;
    private Text text;
    private Table table;
    private int visibleItemCount = 4;
    private Shell popup;
    private Button arrow;
    private boolean hasFocus;
    private Listener listener, filter;
    private Color foreground, background;
    private Font font;
    private int style;

    /**
     * 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#DROP_DOWN
     * @see SWT#READ_ONLY
     * @see SWT#SIMPLE
     * @see Widget#checkSubclass
     * @see Widget#getStyle
     */
    public ImageCombo(Composite parent, int style) {
        super(parent, style = checkStyle(style));
        this.style = style;
        /* This code is intentionally commented */
        //if ((style & SWT.H_SCROLL) != 0) this.style |= SWT.H_SCROLL;
        this.style |= SWT.H_SCROLL;

        int textStyle = SWT.SINGLE;
        if ( (style & SWT.READ_ONLY) != 0 ) {
            textStyle |= SWT.READ_ONLY;
        }
        if ( (style & SWT.FLAT) != 0 ) {
            textStyle |= SWT.FLAT;
        }

        this.comboComposite = new Composite(this, SWT.NONE);
        TableWrapLayout tableWrapLayout = new TableWrapLayout();
        tableWrapLayout.numColumns = 2;
        tableWrapLayout.topMargin = 2;
        tableWrapLayout.bottomMargin = 0;
        tableWrapLayout.leftMargin = 2;
        tableWrapLayout.rightMargin = 0;
        this.comboComposite.setLayout(tableWrapLayout);
        this.comboComposite.setLayoutData(new TableWrapData());

        this.imageLabel = new Label(this.comboComposite, SWT.NONE);
        this.imageLabel.setLayoutData(new TableWrapData());

        this.text = new Text(this.comboComposite, SWT.READ_ONLY);
        this.text.setLayoutData(new TableWrapData(TableWrapData.FILL_GRAB));

        this.comboComposite.setCursor(getDisplay().getSystemCursor(SWT.CURSOR_ARROW));

        int arrowStyle = SWT.ARROW | SWT.DOWN;
        if ( (style & SWT.FLAT) != 0 ) {
            arrowStyle |= SWT.FLAT;
        }
        this.arrow = new Button(this, arrowStyle);

        this.listener = new Listener() {
            public void handleEvent(Event event) {
                if ( ImageCombo.this.popup == event.widget ) {
                    popupEvent(event);
                    return;
                }
                if ( ImageCombo.this.text == event.widget ) {
                    textEvent(event);
                    return;
                }
                if ( ImageCombo.this.table == event.widget ) {
                    listEvent(event);
                    return;
                }
                if ( ImageCombo.this.arrow == event.widget ) {
                    arrowEvent(event);
                    return;
                }
                if ( ImageCombo.this == event.widget ) {
                    comboEvent(event);
                    return;
                }
                if ( getShell() == event.widget ) {
                    handleFocus(SWT.FocusOut);
                }
            }
        };
        this.filter = new Listener() {
            public void handleEvent(Event event) {
                Shell shell = ((Control) event.widget).getShell();
                if ( shell == ImageCombo.this.getShell() ) {
                    handleFocus(SWT.FocusOut);
                }
            }
        };

        int[] comboEvents = { SWT.Dispose, SWT.Move, SWT.Resize };
        for (int i = 0; i < comboEvents.length; i++) {
            this.addListener(comboEvents[i], this.listener);
        }

        int[] textEvents = { SWT.KeyDown, SWT.KeyUp, SWT.Modify, SWT.MouseDown, SWT.MouseUp, SWT.Traverse, SWT.FocusIn };
        for (int i = 0; i < textEvents.length; i++) {
            this.text.addListener(textEvents[i], this.listener);
        }

        int[] arrowEvents = { SWT.Selection, SWT.FocusIn };
        for (int i = 0; i < arrowEvents.length; i++) {
            this.arrow.addListener(arrowEvents[i], this.listener);
        }

        createPopup(-1);
        initAccessible();
    }

    /**
     * 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(Image image, String string) {
        checkWidget();
        if ( string == null ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }

        TableItem newItem = new TableItem(this.table, SWT.FILL);
        newItem.setText(string);//
        if ( image != null ) {
            newItem.setImage(image);
            this.imageLabel.setImage(image);
        }
    }

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when the receiver's text is modified, by sending
     * it one of the messages defined in the <code>ModifyListener</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 ModifyListener
     * @see #removeModifyListener
     */
    public void addModifyListener(ModifyListener listener) {
        checkWidget();
        if ( listener == null ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        TypedListener typedListener = new TypedListener(listener);
        addListener(SWT.Modify, typedListener);
    }

    /**
     * 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 user changes the combo's list selection.
     * <code>widgetDefaultSelected</code> is typically called when ENTER is pressed the combo's text area.
     * </p>
     *
     * @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 SelectionListener
     * @see #removeSelectionListener
     * @see SelectionEvent
     */
    public void addSelectionListener(SelectionListener listener) {
        checkWidget();
        if ( listener == null ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        TypedListener typedListener = new TypedListener(listener);
        addListener(SWT.Selection, typedListener);
        addListener(SWT.DefaultSelection, typedListener);
    }

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when the receiver's text is verified, by sending
     * it one of the messages defined in the <code>VerifyListener</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 VerifyListener
     * @see #removeVerifyListener
     * 
     * @since 3.1
     */
    public void addVerifyListener(VerifyListener listener) {
        checkWidget();
        if ( listener == null ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        TypedListener typedListener = new TypedListener(listener);
        addListener(SWT.Verify, typedListener);
    }

    static int checkStyle(int style) {
        int mask = SWT.BORDER | SWT.READ_ONLY | SWT.FLAT | SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT;
        return style & mask;
    }

    public Point computeSize(int wHint, int hHint, boolean changed) {
        checkWidget();
        int width = 0, height = 0;
        String[] items = getStringsFromTable();
        int textWidth = 0;
        GC gc = new GC(this.comboComposite);
        int spacer = gc.stringExtent(" ").x; //$NON-NLS-1$
        for (int i = 0; i < items.length; i++) {
            textWidth = Math.max(gc.stringExtent(items[i]).x, textWidth);
        }
        gc.dispose();
        Point textSize = this.comboComposite.computeSize(SWT.DEFAULT, SWT.DEFAULT, changed);
        Point arrowSize = this.arrow.computeSize(SWT.DEFAULT, SWT.DEFAULT, changed);
        Point listSize = this.table.computeSize(wHint, SWT.DEFAULT, changed);
        int borderWidth = getBorderWidth();

        height = Math.max(hHint, Math.max(textSize.y, arrowSize.y) + 2 * borderWidth);
        width = Math.max(wHint, Math.max(textWidth + 2 * spacer + arrowSize.x + 2 * borderWidth, listSize.x));
        return new Point(width + 10, height);
    }

    /**
     * Deselects the item at the given zero-relative index in the receiver's 
     * list.  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();
        this.table.deselect(index);
    }

    /**
     * Deselects all selected items in the receiver's list.
     * <p>
     * Note: To clear the selection in the receiver's text field,
     * use <code>clearSelection()</code>.
     * </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>
     *
     * @see #clearSelection
     */
    public void deselectAll() {
        checkWidget();
        this.text.clearSelection();
        this.table.deselectAll();
    }

    /**
     * Returns the item at the given, zero-relative index in the
     * receiver's list. 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();
        return this.table.getItem(index).getText();
    }

    /**
     * Returns the number of items contained in the receiver's list.
     *
     * @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 this.table.getItemCount();
    }

    /**
     * Returns the height of the area which would be used to
     * display <em>one</em> of the items in the receiver's 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();
        return this.table.getItemHeight();
    }

    /**
     * Returns a (possibly empty) array of <code>String</code>s which are
     * the items in the receiver's list. 
     * <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 TableItem[] getItems() {
        checkWidget();
        return this.table.getItems();
    }

    /**
     * Returns the orientation of the receiver.
     *
     * @return the orientation style
     * 
     * @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>
     * 
     * @since 2.1.2
     */
    public int getOrientation() {
        checkWidget();
        return this.style & (SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT);
    }

    /**
     * Returns a <code>Point</code> whose x coordinate is the
     * character position representing the start of the selection
     * in the receiver's text field, and whose y coordinate is the
     * character position representing the end of the selection.
     * An "empty" selection is indicated by the x and y coordinates
     * having the same value.
     * <p>
     * Indexing is zero based.  The range of a selection is from
     * 0..N where N is the number of characters in the widget.
     * </p>
     *
     * @return a point representing the selection start and end
     *
     * @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 Point getSelection() {
        checkWidget();
        return this.text.getSize();
    }

    /**
     * Returns the zero-relative index of the item which is currently
     * selected in the receiver's list, or -1 if no item is selected.
     *
     * @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 getSelectionIndex() {
        checkWidget();
        return this.table.getSelectionIndex();
    }

    /**
     * Returns a string containing a copy of the contents of the
     * receiver's text field, or an empty string if there are no
     * contents.
     *
     * @return the receiver's text
     *
     * @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 getText() {
        checkWidget();
        return this.text.getText();
    }

    /**
     * Returns the height of the receivers's text field.
     *
     * @return the text height
     *
     * @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 getTextHeight() {
        checkWidget();
        return this.text.getSize().x;
    }

    /**
     * Gets the number of items that are visible in the drop
     * down portion of the receiver's list.
     * <p>
     * Note: This operation is a hint and is not supported on
     * platforms that do not have this concept.
     * </p>
     *
     * @return the number of items that are 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>
     * 
     * @since 3.0
     */
    public int getVisibleItemCount() {
        checkWidget();
        return this.visibleCount;
    }

    /**
     * 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 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) {
        checkWidget();
        if ( string == null ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        return Arrays.asList(getStringsFromTable()).indexOf(string);
    }

    /**
     * Removes the item from the receiver's list 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();
        this.table.remove(index);
    }

    /**
     * Removes the items from the receiver's list 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();
        this.table.remove(start, end);
    }

    /**
     * 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 ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        int index = -1;
        for (int i = 0, n = this.table.getItemCount(); i < n; i++) {
            if ( this.table.getItem(i).getText().equals(string) ) {
                index = i;
                break;
            }
        }
        remove(index);
    }

    /**
     * Removes all of the items from the receiver's list and clear the
     * contents of receiver's text field.
     * <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();
        this.text.setText(""); //$NON-NLS-1$
        this.table.removeAll();
    }

    /**
     * Removes the listener from the collection of listeners who will
     * be notified when the receiver's text is modified.
     *
     * @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 ModifyListener
     * @see #addModifyListener
     */
    public void removeModifyListener(ModifyListener listener) {
        checkWidget();
        if ( listener == null ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        removeListener(SWT.Modify, listener);
    }

    /**
     * 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 ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        removeListener(SWT.Selection, listener);
        removeListener(SWT.DefaultSelection, listener);
    }

    /**
     * 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();
        if ( index == -1 ) {
            this.table.deselectAll();
            this.text.setText(""); //$NON-NLS-1$
            return;
        }
        if ( 0 <= index && index < this.table.getItemCount() ) {
            if ( index != getSelectionIndex() ) {
                this.imageLabel.setImage(this.table.getItem(index).getImage());
                this.text.setText(this.table.getItem(index).getText());
                this.text.selectAll();
                this.table.select(index);
                this.table.showSelection();
            }
        }
    }

    public void setFont(Font font) {
        checkWidget();
        super.setFont(font);
        this.font = font;
        this.text.setFont(font);
        this.table.setFont(font);
        internalLayout(true);
    }

    /**
     * Sets the contents of the receiver's text field to the
     * given string.
     * <p>
     * Note: The text field in a <code>Combo</code> is typically
     * only capable of displaying a single line of text. Thus,
     * setting the text to a string containing line breaks or
     * other special characters will probably cause it to 
     * display incorrectly.
     * </p>
     *
     * @param string the new text
     *
     * @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 void setText(String string) {
        checkWidget();
        if ( string == null ) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        int index = -1;
        for (int i = 0, n = this.table.getItemCount(); i < n; i++) {
            if ( this.table.getItem(i).getText().equals(string) ) {
                index = i;
                break;
            }
        }
        if ( index == -1 ) {
            this.table.deselectAll();
            this.text.setText(string);
            return;
        }
        this.text.setText(string);
        this.text.selectAll();
        this.table.setSelection(index);
        this.table.showSelection();
    }

    public void setToolTipText(String string) {
        checkWidget();
        super.setToolTipText(string);
        this.arrow.setToolTipText(string);
        this.comboComposite.setToolTipText(string);
    }

    /**
     * Sets the number of items that are visible in the drop
     * down portion of the receiver's list.
     * <p>
     * Note: This operation is a hint and is not supported on
     * platforms that do not have this concept.
     * </p>
     *
     * @param count the new number of items to be 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>
     * 
     * @since 3.0
     */
    public void setVisibleItemCount(int count) {
        checkWidget();
        if ( count < 0 ) {
            return;
        }
        this.visibleItemCount = count;
    }

    /**
     * Gets the editable state.
     *
     * @return whether or not the reciever is editable
     * 
     * @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>
     * 
     * @since 3.0
     */
    public boolean getEditable() {
        checkWidget();
        return this.text.getEditable();
    }

    void handleFocus(int type) {
        if ( isDisposed() ) {
            return;
        }
        switch (type) {
            case SWT.FocusIn: {
                if ( this.hasFocus ) {
                    return;
                }
                if ( getEditable() ) {
                    this.text.selectAll();
                }
                this.hasFocus = true;
                Shell shell = getShell();
                shell.removeListener(SWT.Deactivate, this.listener);
                shell.addListener(SWT.Deactivate, this.listener);
                Display display = getDisplay();
                display.removeFilter(SWT.FocusIn, this.filter);
                display.addFilter(SWT.FocusIn, this.filter);
                Event e = new Event();
                notifyListeners(SWT.FocusIn, e);
                break;
            }
            case SWT.FocusOut: {
                if ( !this.hasFocus ) {
                    return;
                }
                Control focusControl = getDisplay().getFocusControl();
                if ( focusControl == this.arrow || focusControl == this.table || focusControl == this.comboComposite ) {
                    return;
                }
                this.hasFocus = false;
                Shell shell = getShell();
                shell.removeListener(SWT.Deactivate, this.listener);
                Display display = getDisplay();
                display.removeFilter(SWT.FocusIn, this.filter);
                Event e = new Event();
                notifyListeners(SWT.FocusOut, e);
                break;
            }
        }
    }

    void createPopup(int selectionIndex) {
        // create shell and list
        this.popup = new Shell(getShell(), SWT.NO_TRIM | SWT.ON_TOP);
        int style = getStyle();
        int listStyle = SWT.SINGLE | SWT.V_SCROLL;
        if ( (style & SWT.FLAT) != 0 ) {
            listStyle |= SWT.FLAT;
        }
        if ( (style & SWT.RIGHT_TO_LEFT) != 0 ) {
            listStyle |= SWT.RIGHT_TO_LEFT;
        }
        if ( (style & SWT.LEFT_TO_RIGHT) != 0 ) {
            listStyle |= SWT.LEFT_TO_RIGHT;
        }
        // create a table instead of a list.
        this.table = new Table(this.popup, listStyle);
        if ( this.font != null ) {
            this.table.setFont(this.font);
        }
        if ( this.foreground != null ) {
            this.table.setForeground(this.foreground);
        }
        if ( this.background != null ) {
            this.table.setBackground(this.background);
        }

        int[] popupEvents = { SWT.Close, SWT.Paint, SWT.Deactivate };
        for (int i = 0; i < popupEvents.length; i++) {
            this.popup.addListener(popupEvents[i], this.listener);
        }
        int[] listEvents = { SWT.MouseUp, SWT.Selection, SWT.Traverse, SWT.KeyDown, SWT.KeyUp, SWT.FocusIn, SWT.Dispose };
        for (int i = 0; i < listEvents.length; i++) {
            this.table.addListener(listEvents[i], this.listener);
        }

        if ( selectionIndex != -1 ) {
            this.table.setSelection(selectionIndex);
        }
    }

    boolean isDropped() {
        return this.popup.getVisible();
    }

    void dropDown(boolean drop) {
        if ( drop == isDropped() ) {
            return;
        }
        if ( !drop ) {
            this.popup.setVisible(false);
            if ( !isDisposed() && this.arrow.isFocusControl() ) {
                this.comboComposite.setFocus();
            }
            return;
        }

        if ( getShell() != this.popup.getParent() ) {
            int selectionIndex = this.table.getSelectionIndex();
            this.table.removeListener(SWT.Dispose, this.listener);
            this.popup.dispose();
            this.popup = null;
            this.table = null;
            createPopup(selectionIndex);
        }

        Point size = getSize();
        int itemCount = this.table.getItemCount();
        itemCount = (itemCount == 0) ? this.visibleItemCount : Math.min(this.visibleItemCount, itemCount);
        int itemHeight = this.table.getItemHeight() * itemCount;
        Point listSize = this.table.computeSize(SWT.DEFAULT, itemHeight, false);
        this.table.setBounds(1, 1, Math.max(size.x - 2, listSize.x), listSize.y);

        int index = this.table.getSelectionIndex();
        if ( index != -1 ) {
            this.table.setTopIndex(index);
        }
        Display display = getDisplay();
        Rectangle listRect = this.table.getBounds();
        Rectangle parentRect = display.map(getParent(), null, getBounds());
        Point comboSize = getSize();
        Rectangle displayRect = getMonitor().getClientArea();
        int width = Math.max(comboSize.x, listRect.width + 2);
        int height = listRect.height + 2;
        int x = parentRect.x;
        int y = parentRect.y + comboSize.y;
        if ( y + height > displayRect.y + displayRect.height ) {
            y = parentRect.y - height;
        }
        this.popup.setBounds(x, y, width, height);
        this.popup.setVisible(true);
        this.table.setFocus();
    }

    void listEvent(Event event) {
        switch (event.type) {
            case SWT.Dispose:
                if ( getShell() != this.popup.getParent() ) {
                    int selectionIndex = this.table.getSelectionIndex();
                    this.popup = null;
                    this.table = null;
                    createPopup(selectionIndex);
                }
                break;
            case SWT.FocusIn: {
                handleFocus(SWT.FocusIn);
                break;
            }
            case SWT.MouseUp: {
                if ( event.button != 1 ) {
                    return;
                }
                dropDown(false);
                break;
            }
            case SWT.Selection: {
                int index = this.table.getSelectionIndex();
                if ( index == -1 ) {
                    return;
                }
                this.text.setText(this.table.getItem(index).getText());
                this.text.selectAll();
                this.imageLabel.setImage(this.table.getItem(index).getImage());
                this.table.setSelection(index);
                Event e = new Event();
                e.time = event.time;
                e.stateMask = event.stateMask;
                e.doit = event.doit;
                notifyListeners(SWT.Selection, e);
                event.doit = e.doit;
                break;
            }
            case SWT.Traverse: {
                switch (event.detail) {
                    case SWT.TRAVERSE_RETURN:
                    case SWT.TRAVERSE_ESCAPE:
                    case SWT.TRAVERSE_ARROW_PREVIOUS:
                    case SWT.TRAVERSE_ARROW_NEXT:
                        event.doit = false;
                        break;
                }
                Event e = new Event();
                e.time = event.time;
                e.detail = event.detail;
                e.doit = event.doit;
                e.character = event.character;
                e.keyCode = event.keyCode;
                notifyListeners(SWT.Traverse, e);
                event.doit = e.doit;
                event.detail = e.detail;
                break;
            }
            case SWT.KeyUp: {
                Event e = new Event();
                e.time = event.time;
                e.character = event.character;
                e.keyCode = event.keyCode;
                e.stateMask = event.stateMask;
                notifyListeners(SWT.KeyUp, e);
                break;
            }
            case SWT.KeyDown: {
                if ( event.character == SWT.ESC ) {
                    // Escape key cancels popup list
                    dropDown(false);
                }
                if ( (event.stateMask & SWT.ALT) != 0
                                && (event.keyCode == SWT.ARROW_UP || event.keyCode == SWT.ARROW_DOWN) ) {
                    dropDown(false);
                }
                if ( event.character == SWT.CR ) {
                    // Enter causes default selection
                    dropDown(false);
                    Event e = new Event();
                    e.time = event.time;
                    e.stateMask = event.stateMask;
                    notifyListeners(SWT.DefaultSelection, e);
                }
                // At this point the widget may have been disposed.
                // If so, do not continue.
                if ( isDisposed() ) {
                    break;
                }
                Event e = new Event();
                e.time = event.time;
                e.character = event.character;
                e.keyCode = event.keyCode;
                e.stateMask = event.stateMask;
                notifyListeners(SWT.KeyDown, e);
                break;

            }
        }
    }

    void arrowEvent(Event event) {
        switch (event.type) {
            case SWT.FocusIn: {
                handleFocus(SWT.FocusIn);
                break;
            }
            case SWT.Selection: {
                dropDown(!isDropped());
                break;
            }
        }
    }

    void comboEvent(Event event) {
        switch (event.type) {
            case SWT.Dispose:
                if ( this.popup != null && !this.popup.isDisposed() ) {
                    this.table.removeListener(SWT.Dispose, this.listener);
                    this.popup.dispose();
                }
                Shell shell = getShell();
                shell.removeListener(SWT.Deactivate, this.listener);
                Display display = getDisplay();
                display.removeFilter(SWT.FocusIn, this.filter);
                this.popup = null;
                this.comboComposite = null;
                this.table = null;
                this.arrow = null;
                break;
            case SWT.Move:
                dropDown(false);
                break;
            case SWT.Resize:
                internalLayout(false);
                break;
        }
    }

    void internalLayout(boolean changed) {
        if ( isDropped() ) {
            dropDown(false);
        }
        Rectangle rect = getClientArea();
        int width = rect.width;
        int height = rect.height;
        Point arrowSize = this.arrow.computeSize(SWT.DEFAULT, height, changed);
        this.comboComposite.setBounds(0, 0, width - arrowSize.x, height);
        this.arrow.setBounds(width - arrowSize.x, 0, arrowSize.x, arrowSize.y);
    }

    void popupEvent(Event event) {
        switch (event.type) {
            case SWT.Paint:
                // draw black rectangle around list
                Rectangle listRect = this.table.getBounds();
                Color black = getDisplay().getSystemColor(SWT.COLOR_BLACK);
                event.gc.setForeground(black);
                event.gc.drawRectangle(0, 0, listRect.width + 1, listRect.height + 1);
                break;
            case SWT.Close:
                event.doit = false;
                dropDown(false);
                break;
            case SWT.Deactivate:
                dropDown(false);
                break;
        }
    }

    Label getAssociatedLabel() {
        Control[] siblings = getParent().getChildren();
        for (int i = 0; i < siblings.length; i++) {
            if ( siblings[i] == ImageCombo.this ) {
                if ( i > 0 && siblings[i - 1] instanceof Label ) {
                    return (Label) siblings[i - 1];
                }
            }
        }
        return null;
    }

    char getMnemonic(String string) {
        int index = 0;
        int length = string.length();
        do {
            while ((index < length) && (string.charAt(index) != '&')) {
                index++;
            }
            if ( ++index >= length ) {
                return '\0';
            }
            if ( string.charAt(index) != '&' ) {
                return string.charAt(index);
            }
            index++;
        } while (index < length);
        return '\0';
    }

    String[] getStringsFromTable() {
        String[] items = new String[this.table.getItems().length];
        for (int i = 0, n = items.length; i < n; i++) {
            items[i] = this.table.getItem(i).getText();
        }
        return items;
    }

    String stripMnemonic(String string) {
        int index = 0;
        int length = string.length();
        do {
            while ((index < length) && (string.charAt(index) != '&')) {
                index++;
            }
            if ( ++index >= length ) {
                return string;
            }
            if ( string.charAt(index) != '&' ) {
                return string.substring(0, index - 1) + string.substring(index, length);
            }
            index++;
        } while (index < length);
        return string;
    }

    void initAccessible() {
        AccessibleAdapter accessibleAdapter = new AccessibleAdapter() {
            public void getName(AccessibleEvent e) {
                String name = null;
                Label label = getAssociatedLabel();
                if ( label != null ) {
                    name = stripMnemonic(label.getText());
                }
                e.result = name;
            }

            public void getKeyboardShortcut(AccessibleEvent e) {
                String shortcut = null;
                Label label = getAssociatedLabel();
                if ( label != null ) {
                    String text = label.getText();
                    if ( text != null ) {
                        char mnemonic = getMnemonic(text);
                        if ( mnemonic != '\0' ) {
                            shortcut = "Alt+" + mnemonic; //$NON-NLS-1$
                        }
                    }
                }
                e.result = shortcut;
            }

            public void getHelp(AccessibleEvent e) {
                e.result = getToolTipText();
            }
        };
        getAccessible().addAccessibleListener(accessibleAdapter);
        this.comboComposite.getAccessible().addAccessibleListener(accessibleAdapter);
        this.table.getAccessible().addAccessibleListener(accessibleAdapter);

        this.arrow.getAccessible().addAccessibleListener(new AccessibleAdapter() {
            public void getName(AccessibleEvent e) {
                e.result = isDropped() ? SWT.getMessage("SWT_Close") : SWT.getMessage("SWT_Open"); //$NON-NLS-1$ //$NON-NLS-2$
            }

            public void getKeyboardShortcut(AccessibleEvent e) {
                e.result = "Alt+Down Arrow"; //$NON-NLS-1$
            }

            public void getHelp(AccessibleEvent e) {
                e.result = getToolTipText();
            }
        });

        getAccessible().addAccessibleTextListener(new AccessibleTextAdapter() {
            public void getCaretOffset(AccessibleTextEvent e) {
                e.offset = ImageCombo.this.text.getCaretPosition();
            }
        });

        getAccessible().addAccessibleControlListener(new AccessibleControlAdapter() {
            public void getChildAtPoint(AccessibleControlEvent e) {
                Point testPoint = toControl(e.x, e.y);
                if ( getBounds().contains(testPoint) ) {
                    e.childID = ACC.CHILDID_SELF;
                }
            }

            public void getLocation(AccessibleControlEvent e) {
                Rectangle location = getBounds();
                Point pt = toDisplay(location.x, location.y);
                e.x = pt.x;
                e.y = pt.y;
                e.width = location.width;
                e.height = location.height;
            }

            public void getChildCount(AccessibleControlEvent e) {
                e.detail = 0;
            }

            public void getRole(AccessibleControlEvent e) {
                e.detail = ACC.ROLE_COMBOBOX;
            }

            public void getState(AccessibleControlEvent e) {
                e.detail = ACC.STATE_NORMAL;
            }

            public void getValue(AccessibleControlEvent e) {
                e.result = getText();
            }
        });

        this.text.getAccessible().addAccessibleControlListener(new AccessibleControlAdapter() {
            public void getRole(AccessibleControlEvent e) {
                e.detail = ACC.ROLE_LABEL;
            }
        });

        this.arrow.getAccessible().addAccessibleControlListener(new AccessibleControlAdapter() {
            public void getDefaultAction(AccessibleControlEvent e) {
                e.result = isDropped() ? SWT.getMessage("SWT_Close") : SWT.getMessage("SWT_Open"); //$NON-NLS-1$ //$NON-NLS-2$
            }
        });
    }

    void textEvent(Event event) {
        switch (event.type) {
            case SWT.FocusIn: {
                handleFocus(SWT.FocusIn);
                break;
            }
            case SWT.KeyDown: {
                if ( event.character == SWT.CR ) {
                    dropDown(false);
                    Event e = new Event();
                    e.time = event.time;
                    e.stateMask = event.stateMask;
                    notifyListeners(SWT.DefaultSelection, e);
                }
                //At this point the widget may have been disposed.
                // If so, do not continue.
                if ( isDisposed() ) {
                    break;
                }

                if ( event.keyCode == SWT.ARROW_UP || event.keyCode == SWT.ARROW_DOWN ) {
                    event.doit = false;
                    if ( (event.stateMask & SWT.ALT) != 0 ) {
                        boolean dropped = isDropped();
                        this.text.selectAll();
                        if ( !dropped ) {
                            setFocus();
                        }
                        dropDown(!dropped);
                        break;
                    }

                    int oldIndex = getSelectionIndex();
                    if ( event.keyCode == SWT.ARROW_UP ) {
                        select(Math.max(oldIndex - 1, 0));
                    } else {
                        select(Math.min(oldIndex + 1, getItemCount() - 1));
                    }
                    if ( oldIndex != getSelectionIndex() ) {
                        Event e = new Event();
                        e.time = event.time;
                        e.stateMask = event.stateMask;
                        notifyListeners(SWT.Selection, e);
                    }
                    //At this point the widget may have been disposed.
                    // If so, do not continue.
                    if ( isDisposed() ) {
                        break;
                    }
                }

                // Further work : Need to add support for incremental search in 
                // pop up list as characters typed in text widget

                Event e = new Event();
                e.time = event.time;
                e.character = event.character;
                e.keyCode = event.keyCode;
                e.stateMask = event.stateMask;
                notifyListeners(SWT.KeyDown, e);
                break;
            }
            case SWT.KeyUp: {
                Event e = new Event();
                e.time = event.time;
                e.character = event.character;
                e.keyCode = event.keyCode;
                e.stateMask = event.stateMask;
                notifyListeners(SWT.KeyUp, e);
                break;
            }
            case SWT.Modify: {
                this.table.deselectAll();
                Event e = new Event();
                e.time = event.time;
                notifyListeners(SWT.Modify, e);
                break;
            }
            case SWT.MouseDown: {
                if ( event.button != 1 ) {
                    return;
                }
                if ( this.text.getEditable() ) {
                    return;
                }
                boolean dropped = isDropped();
                this.text.selectAll();
                if ( !dropped ) {
                    setFocus();
                }
                dropDown(!dropped);
                break;
            }
            case SWT.MouseUp: {
                if ( event.button != 1 ) {
                    return;
                }
                if ( this.text.getEditable() ) {
                    return;
                }
                this.text.selectAll();
                break;
            }
            case SWT.Traverse: {
                switch (event.detail) {
                    case SWT.TRAVERSE_RETURN:
                    case SWT.TRAVERSE_ARROW_PREVIOUS:
                    case SWT.TRAVERSE_ARROW_NEXT:
                        // The enter causes default selection and
                        // the arrow keys are used to manipulate the list contents so
                        // do not use them for traversal.
                        event.doit = false;
                        break;
                }

                Event e = new Event();
                e.time = event.time;
                e.detail = event.detail;
                e.doit = event.doit;
                e.character = event.character;
                e.keyCode = event.keyCode;
                notifyListeners(SWT.Traverse, e);
                event.doit = e.doit;
                event.detail = e.detail;
                break;
            }
        }
    }
}