org.eclipse.swt.widgets.Combo.java Source code

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/*******************************************************************************
 * Copyright (c) 2002, 2015 Innoopract Informationssysteme GmbH 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:
 *    Innoopract Informationssysteme GmbH - initial API and implementation
 *    EclipseSource - ongoing development
 ******************************************************************************/
package org.eclipse.swt.widgets;

import org.eclipse.rap.rwt.internal.lifecycle.WidgetLCA;
import org.eclipse.rap.rwt.internal.textsize.TextSizeUtil;
import org.eclipse.rap.rwt.internal.theme.ThemeAdapter;
import org.eclipse.rap.rwt.theme.BoxDimensions;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
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.Font;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.internal.graphics.FontUtil;
import org.eclipse.swt.internal.widgets.ITextAdapter;
import org.eclipse.swt.internal.widgets.ListModel;
import org.eclipse.swt.internal.widgets.combokit.ComboLCA;
import org.eclipse.swt.internal.widgets.combokit.ComboThemeAdapter;

/**
 * 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</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
 * @since 1.0
 */
public class Combo extends Composite {

    /**
     * The maximum number of characters that can be entered
     * into a text widget.
     * @since 1.3
     */
    public static final int LIMIT = Integer.MAX_VALUE;

    // Must be in sync with appearance "list-item"
    private static final int LIST_ITEM_PADDING = 3;

    private static final double LINE_HEIGHT_FACTOR = 1.4;

    private ITextAdapter textAdapter;
    private final ListModel model;
    private String text;
    private int textLimit;
    private int visibleCount;
    private final Point selection;
    private boolean dropped;

    /**
     * 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 Combo(Composite parent, int style) {
        super(parent, checkStyle(style));
        text = "";
        visibleCount = 5;
        dropped = false;
        textLimit = LIMIT;
        selection = new Point(0, 0);
        model = new ListModel(true);
    }

    @Override
    void initState() {
        removeState( /* CANVAS | */THEME_BACKGROUND);
    }

    /**
     * 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 model.getSelectionIndex();
    }

    /**
     * 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 selectionIndex 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 selectionIndex) {
        checkWidget();
        if (0 <= selectionIndex && selectionIndex < getItemCount()) {
            model.setSelection(selectionIndex);
            updateText();
        }
    }

    /**
     * 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();
        if (index == model.getSelectionIndex()) {
            model.setSelection(-1);
        }
        updateText();
    }

    /**
     * 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();
        model.deselectAll();
        text = "";
        notifyListeners(SWT.Modify, new Event());
    }

    /**
     * Sets the selection in the receiver's text field to the
     * range specified by the argument whose x coordinate is the
     * start of the selection and whose y coordinate is the end
     * of the selection.
     *
     * @param selection a point representing the new selection start and end
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the point 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>
     *
     * @since 1.3
     */
    public void setSelection(Point selection) {
        checkWidget();
        if (selection == null) {
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        }
        int validatedStart = this.selection.x;
        int validatedEnd = this.selection.y;
        int start = selection.x;
        int end = selection.y;
        if (start >= 0 && end >= start) {
            validatedStart = Math.min(start, text.length());
            validatedEnd = Math.min(end, text.length());
        } else if (end >= 0 && start > end) {
            validatedStart = Math.min(end, text.length());
            validatedEnd = Math.min(start, text.length());
        }
        this.selection.x = validatedStart;
        this.selection.y = validatedEnd;
    }

    /**
     * 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>
     *
     * @since 1.3
     */
    public Point getSelection() {
        checkWidget();
        return new Point(selection.x, selection.y);
    }

    /**
     * Sets the selection in the receiver's text field to an empty
     * selection starting just before the first character. If the
     * text field is editable, this has the effect of placing the
     * i-beam at the start of the text.
     * <p>
     * Note: To clear the selected items in the receiver's list,
     * use <code>deselectAll()</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 #deselectAll
     *
     * @since 1.3
     */
    public void clearSelection() {
        checkWidget();
        resetSelection();
    }

    /**
     * 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();
        model.add(string);
    }

    /**
     * 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();
        model.add(string, index);
    }

    /**
     * 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();
        int selectionIndex = getSelectionIndex();
        if (selectionIndex == index) {
            deselect(index);
        }
        model.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();
        String[] items = model.getItems();
        int lastIndex = items.length - 1;
        if (start < 0 || start > lastIndex || end < 0 || end > lastIndex || end < start) {
            error(SWT.ERROR_INVALID_RANGE);
        }
        int selectionIndex = getSelectionIndex();
        for (int i = start; i <= end; i++) {
            int index = indexOf(items[i]);
            if (selectionIndex == index) {
                deselect(index);
            }
        }
        model.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();
        int indexOfThisString = indexOf(string);
        int selectionIndex = getSelectionIndex();
        if (selectionIndex == indexOfThisString) {
            deselect(indexOfThisString);
        }
        model.remove(string);
    }

    /**
     * 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();
        deselectAll();
        model.removeAll();
    }

    /**
     * Sets the text of the item in the receiver's list at the given
     * zero-relative index to the string argument. This is equivalent
     * to removing the old item at the index, and then adding the new
     * item at that index.
     *
     * @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();
        model.setItem(index, string);
    }

    /**
     * Sets the receiver's list 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();
        model.setItems(items);
    }

    /**
     * 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 model.getItem(index);
    }

    /**
     * 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 String[] getItems() {
        checkWidget();
        return model.getItems();
    }

    /**
     * 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 model.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>
     *
     * @since 1.3
     */
    public int getItemHeight() {
        checkWidget();
        int charHeight = TextSizeUtil.getCharHeight(getFont());
        int padding = 2 * LIST_ITEM_PADDING;
        return charHeight + padding;
    }

    /**
     * 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>
     */
    public void setVisibleItemCount(int count) {
        checkWidget();
        if (count >= 0) {
            visibleCount = count;
        }
    }

    /**
     * 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>
     */
    public int getVisibleItemCount() {
        checkWidget();
        return visibleCount;
    }

    /**
     * Marks the receiver's list as visible if the argument is <code>true</code>,
     * and marks it invisible otherwise.
     * <p>
     * If one of the receiver's ancestors is not visible or some
     * other condition makes the receiver not visible, marking
     * it visible may not actually cause it to be displayed.
     * </p>
     *
     * @param visible the new visibility state
     *
     * @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 1.3
     */
    public void setListVisible(boolean visible) {
        checkWidget();
        dropped = visible;
    }

    /**
     * Returns <code>true</code> if the receiver's list is visible,
     * and <code>false</code> otherwise.
     * <p>
     * If one of the receiver's ancestors is not visible or some
     * other condition makes the receiver not visible, this method
     * may still indicate that it is considered visible even though
     * it may not actually be showing.
     * </p>
     *
     * @return the receiver's list's visibility state
     *
     * @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 1.3
     */
    public boolean getListVisible() {
        checkWidget();
        return dropped;
    }

    /**
     * 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();
        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 begin 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);
        }
        return model.indexOf(string, start);
    }

    /**
     * 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();
        String result = "";
        if ((style & SWT.READ_ONLY) != 0) {
            int idx = model.getSelectionIndex();
            if (idx != -1) {
                result = model.getItem(idx);
            }
        } else {
            result = text;
        }
        return result;
    }

    /**
     * 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) {
            error(SWT.ERROR_NULL_ARGUMENT);
        }
        if ((style & SWT.READ_ONLY) != 0) {
            int index = indexOf(string);
            if (index != -1) {
                select(index);
                selection.x = 0;
                selection.y = string.length();
            }
        } else if (internalSetText(string, true)) {
            resetSelection();
            notifyListeners(SWT.Modify, new Event());
        }
    }

    /**
     * Returns the maximum number of characters that the receiver's
     * text field is capable of holding. If this has not been changed
     * by <code>setTextLimit()</code>, it will be the constant
     * <code>Combo.LIMIT</code>.
     *
     * @return the text limit
     *
     * @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 #LIMIT
     * @since 1.3
     */
    public int getTextLimit() {
        checkWidget();
        return textLimit;
    }

    /**
     * Sets the maximum number of characters that the receiver's
     * text field is capable of holding to be the argument.
     * <p>
     * To reset this value to the default, use <code>setTextLimit(Combo.LIMIT)</code>.
     * Specifying a limit value larger than <code>Combo.LIMIT</code> sets the
     * receiver's limit to <code>Combo.LIMIT</code>.
     * </p>
     * @param limit new text limit
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_CANNOT_BE_ZERO - if the limit is zero</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 #LIMIT
     * @since 1.3
     */
    public void setTextLimit(int limit) {
        checkWidget();
        if (limit == 0) {
            error(SWT.ERROR_CANNOT_BE_ZERO);
        }
        if (limit > 0) {
            textLimit = limit;
        } else {
            textLimit = LIMIT;
        }
    }

    /**
     * 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>
     *
     * @since 1.3
     */
    public int getTextHeight() {
        checkWidget();
        Font font = getFont();
        int fontSize = FontUtil.getData(font).getHeight();
        return (int) Math.floor(fontSize * LINE_HEIGHT_FACTOR);
    }

    // TODO [rst] Revise: In SWT, a width or height hint of 0 does not result in
    //      the DEFAULT_WIDTH/HEIGHT.
    @Override
    public Point computeSize(int wHint, int hHint, boolean changed) {
        checkWidget();
        int width = 0;
        int height = TextSizeUtil.getCharHeight(getFont());
        if (wHint == SWT.DEFAULT || hHint == SWT.DEFAULT) {
            String[] items = model.getItems();
            for (int i = 0; i < items.length; i++) {
                if (!"".equals(items[i])) {
                    Point extent = TextSizeUtil.stringExtent(getFont(), items[i]);
                    width = Math.max(width, extent.x + 10);
                }
            }
        }
        BoxDimensions fieldPadding = getFieldPadding();
        int buttonWidth = getButtonWidth();
        if (width != 0) {
            width += fieldPadding.left + fieldPadding.right + buttonWidth;
        }
        if (height != 0) {
            height += fieldPadding.top + fieldPadding.bottom;
            // TODO [rst] Workaround for two missing pixels (, p are cut off), revise
            height += 2;
        }
        if (width == 0) {
            width = DEFAULT_WIDTH;
        }
        if (height == 0) {
            height = DEFAULT_HEIGHT;
        }
        if (wHint != SWT.DEFAULT) {
            width = wHint;
        }
        if (hHint != SWT.DEFAULT) {
            height = hHint;
        }
        BoxDimensions border = getBorder();
        height += border.top + border.bottom;
        width += border.left + border.right;
        return new Point(width, height);
    }

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when the receiver's selection changes, by sending
     * it one of the messages defined in the <code>SelectionListener</code>
     * interface.
     * <p>
     * <code>widgetSelected</code> is called when the combo's list selection changes.
     * <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);
    }

    /**
     * Removes the listener from the collection of listeners who will
     * be notified when the receiver's selection changes.
     *
     * @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);
    }

    /**
     * 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);
    }

    /**
     * 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);
    }

    /**
     * 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
     */
    public void addVerifyListener(VerifyListener listener) {
        checkWidget();
        if (listener == null) {
            error(SWT.ERROR_NULL_ARGUMENT);
        }
        TypedListener typedListener = new TypedListener(listener);
        addListener(SWT.Verify, typedListener);
    }

    /**
     * Removes the listener from the collection of listeners who will
     * be notified when the control is verified.
     *
     * @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 VerifyListener
     * @see #addVerifyListener
     */
    public void removeVerifyListener(VerifyListener listener) {
        checkWidget();
        if (listener == null) {
            error(SWT.ERROR_NULL_ARGUMENT);
        }
        removeListener(SWT.Verify, listener);
    }

    @Override
    @SuppressWarnings("unchecked")
    public <T> T getAdapter(Class<T> adapter) {
        if (adapter == ITextAdapter.class) {
            if (textAdapter == null) {
                textAdapter = new ITextAdapter() {
                    @Override
                    public void setText(String text) {
                        if (internalSetText(text, true)) {
                            adjustSelection();
                            notifyListeners(SWT.Modify, new Event());
                        }
                    }
                };
            }
            return (T) textAdapter;
        }
        if (adapter == WidgetLCA.class) {
            return (T) ComboLCA.INSTANCE;
        }
        return super.getAdapter(adapter);
    }

    @Override
    boolean isTabGroup() {
        return true;
    }

    @Override
    String getNameText() {
        return getText();
    }

    private void updateText() {
        if ((style & SWT.READ_ONLY) == 0) {
            int selectionIndex = getSelectionIndex();
            String text = selectionIndex != -1 ? getItem(selectionIndex) : "";
            if (internalSetText(text, false)) {
                adjustSelection();
                notifyListeners(SWT.Modify, new Event());
            }
        } else {
            notifyListeners(SWT.Modify, new Event());
        }
    }

    private boolean internalSetText(String text, boolean updateSelection) {
        String verifiedText = verifyText(text, 0, this.text.length());
        if (verifiedText != null) {
            if (updateSelection) {
                int index = -1;
                String[] items = model.getItems();
                for (int i = 0; index == -1 && i < items.length; i++) {
                    if (verifiedText.equals(items[i])) {
                        index = i;
                    }
                }
                model.setSelection(index);
            }
            if (verifiedText.length() > textLimit) {
                this.text = verifiedText.substring(0, textLimit);
            } else {
                this.text = verifiedText;
            }
        }
        return verifiedText != null;
    }

    private String verifyText(String text, int start, int end) {
        Event event = new Event();
        event.text = text;
        event.start = start;
        event.end = end;
        notifyListeners(SWT.Verify, event);
        /*
         * It is possible (but unlikely), that application code could have disposed
         * the widget in the verify event. If this happens, answer null to cancel
         * the operation.
         */
        String result;
        if (event.doit && !isDisposed()) {
            result = event.text;
        } else {
            return null;
        }
        return result;
    }

    private void resetSelection() {
        selection.x = 0;
        selection.y = 0;
    }

    private void adjustSelection() {
        selection.x = Math.min(selection.x, text.length());
        selection.y = Math.min(selection.y, text.length());
    }

    private BoxDimensions getFieldPadding() {
        return getThemeAdapter().getFieldPadding(this);
    }

    private int getButtonWidth() {
        return getThemeAdapter().getButtonWidth(this);
    }

    private ComboThemeAdapter getThemeAdapter() {
        return (ComboThemeAdapter) getAdapter(ThemeAdapter.class);
    }

    private static int checkStyle(int style) {
        int result = style;
        /*
         * Feature in Windows.  It is not possible to create
         * a combo box that has a border using Windows style
         * bits.  All combo boxes draw their own border and
         * do not use the standard Windows border styles.
         * Therefore, no matter what style bits are specified,
         * clear the BORDER bits so that the SWT style will
         * match the Windows widget.
         *
         * The Windows behavior is currently implemented on
         * all platforms.
         */
        result &= ~SWT.BORDER;

        /*
         * Even though it is legal to create this widget
         * with scroll bars, they serve no useful purpose
         * because they do not automatically scroll the
         * widget's client area.  The fix is to clear
         * the SWT style.
         */
        result &= ~(SWT.H_SCROLL | SWT.V_SCROLL);
        result = checkBits(result, SWT.DROP_DOWN, SWT.SIMPLE, 0, 0, 0, 0);
        if ((result & SWT.SIMPLE) != 0) {
            return result & ~SWT.READ_ONLY;
        }
        return result;
    }
}