/*******************************************************************************
 * Copyright (c) 2000, 2003 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
 *     
 * Port to the D programming language:
 *     Jacob Carlborg <doob@me.com>
 *******************************************************************************/
module dwt.accessibility.AccessibleTextListener;

import dwt.accessibility.AccessibleTextEvent;
import dwt.dwthelper.utils;
import dwt.internal.DWTEventListener;

/**
 * Classes that implement this interface provide methods
 * that deal with the events that are generated when an
 * accessibility client sends a message to a control.
 * <p>
 * After creating an instance of a class that implements
 * this interface it can be added to a control using the
 * <code>addAccessibleTextListener</code> method and removed
 * using the <code>removeAccessibleTextListener</code> method.
 * When a client requests information the appropriate method
 * will be invoked.
 * </p><p>
 * Note: Accessibility clients use child identifiers to specify
 * whether they want information about a control or one of its children.
 * Child identifiers are increasing integers beginning with 0.
 * The identifier CHILDID_SELF represents the control itself.
 * </p><p>
 * Note: This interface is typically used by implementors of
 * a custom control to provide very detailed information about
 * the control instance to accessibility clients.
 * </p>
 *
 * @see AccessibleTextAdapter
 * @see AccessibleTextEvent
 * 
 * @since 3.0
 */
public interface AccessibleTextListener : DWTEventListener {
    
    /**
     * Sent when an accessibility client requests the current character offset
     * of the text caret.
     * <p>
     * Return the caret offset in the <code>offset</code>
     * field of the event object.
     * </p>
     *
     * @param e an event object containing the following fields:<ul>
     *    <li>childID [IN] - an identifier specifying a child of the control</li>
     *    <li>offset [OUT] - the current offset of the text caret</li>
     * </ul>
     */
    public void getCaretOffset (AccessibleTextEvent e);
    
    /**
     * Sent when an accessibility client requests the range of the current
     * text selection.
     * <p>
     * Return the selection start offset and non-negative length in the
     * <code>offset</code> and <code>length</code> fields of the event object.
     * </p>
     *
     * @param e an event object containing the following fields:<ul>
     *    <li>childID [IN] - an identifier specifying a child of the control</li>
     *    <li>offset [OUT] - the offset of the current text selection</li>
     *    <li>length [OUT] - the length of the current text selection</li>
     * </ul>
     */
    public void getSelectionRange (AccessibleTextEvent e);
}