| /******************************************************************************* |
| * Copyright (c) 2000, 2008 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.swt.events; |
| |
| |
| import org.eclipse.swt.widgets.*; |
| |
| /** |
| * Instances of this class are sent as a result of |
| * widget traversal actions. |
| * <p> |
| * The traversal event allows fine control over keyboard traversal |
| * in a control both to implement traversal and override the default |
| * traversal behavior defined by the system. This is achieved using |
| * two fields, <code>detail</code> and <code>doit</code>. |
| * </p><p> |
| * When a control is traversed, a traverse event is sent. The detail |
| * describes the type of traversal and the doit field indicates the default |
| * behavior of the system. For example, when a right arrow key is pressed |
| * in a text control, the detail field is <code>TRAVERSE_ARROW_NEXT</code> |
| * and the doit field is <code>false</code>, indicating that the system |
| * will not traverse to the next tab item and the arrow key will be |
| * delivered to the text control. If the same key is pressed in a radio |
| * button, the doit field will be <code>true</code>, indicating that |
| * traversal is to proceed to the next tab item, possibly another radio |
| * button in the group and that the arrow key is not to be delivered |
| * to the radio button. |
| * </p><p> |
| * How can the traversal event be used to implement traversal? |
| * When a tab key is pressed in a canvas, the detail field will be |
| * <code>TRAVERSE_TAB_NEXT</code> and the doit field will be |
| * <code>false</code>. The default behavior of the system is to |
| * provide no traversal for canvas controls. This means that by |
| * default in a canvas, a key listener will see every key that the |
| * user types, including traversal keys. To understand why this |
| * is so, it is important to understand that only the widget implementor |
| * can decide which traversal is appropriate for the widget. Returning |
| * to the <code>TRAVERSE_TAB_NEXT</code> example, a text widget implemented |
| * by a canvas would typically want to use the tab key to insert a |
| * tab character into the widget. A list widget implementation, on the |
| * other hand, would like the system default traversal behavior. Using |
| * only the doit flag, both implementations are possible. The text widget |
| * implementor sets doit to <code>false</code>, ensuring that the system |
| * will not traverse and that the tab key will be delivered to key listeners. |
| * The list widget implementor sets doit to <code>true</code>, indicating |
| * that the system should perform tab traversal and that the key should not |
| * be delivered to the list widget. |
| * </p><p> |
| * How can the traversal event be used to override system traversal? |
| * When the return key is pressed in a single line text control, the |
| * detail field is <code>TRAVERSE_RETURN</code> and the doit field |
| * is <code>true</code>. This means that the return key will be processed |
| * by the default button, not the text widget. If the text widget has |
| * a default selection listener, it will not run because the return key |
| * will be processed by the default button. Imagine that the text control |
| * is being used as an in-place editor and return is used to dispose the |
| * widget. Setting doit to <code>false</code> will stop the system from |
| * activating the default button but the key will be delivered to the text |
| * control, running the key and selection listeners for the text. How |
| * can <code>TRAVERSE_RETURN</code> be implemented so that the default button |
| * will not be activated and the text widget will not see the return key? |
| * This is achieved by setting doit to <code>true</code>, and the detail |
| * to <code>TRAVERSE_NONE</code>. |
| * </p><p> |
| * Note: A widget implementor will typically implement traversal using |
| * only the doit flag to either enable or disable system traversal. |
| * </p> |
| * |
| * @see TraverseListener |
| * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> |
| */ |
| |
| public final class TraverseEvent extends KeyEvent { |
| |
| /** |
| * The traversal type. |
| * <p><ul> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_NONE}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_ESCAPE}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_RETURN}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_TAB_NEXT}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_TAB_PREVIOUS}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_ARROW_NEXT}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_ARROW_PREVIOUS}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_MNEMONIC}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_PAGE_NEXT}</li> |
| * <li>{@link org.eclipse.swt.SWT#TRAVERSE_PAGE_PREVIOUS}</li> |
| * </ul></p> |
| * |
| * Setting this field will change the type of traversal. |
| * For example, setting the detail to <code>TRAVERSE_NONE</code> |
| * causes no traversal action to be taken. |
| * |
| * When used in conjunction with the <code>doit</code> field, the |
| * traversal detail field can be useful when overriding the default |
| * traversal mechanism for a control. For example, setting the doit |
| * field to <code>false</code> will cancel the operation and allow |
| * the traversal key stroke to be delivered to the control. Setting |
| * the doit field to <code>true</code> indicates that the traversal |
| * described by the detail field is to be performed. |
| */ |
| public int detail; |
| |
| static final long serialVersionUID = 3257565105301239349L; |
| |
| /** |
| * Constructs a new instance of this class based on the |
| * information in the given untyped event. |
| * |
| * @param e the untyped event containing the information |
| */ |
| public TraverseEvent(Event e) { |
| super(e); |
| this.detail = e.detail; |
| } |
| |
| /** |
| * Returns a string containing a concise, human-readable |
| * description of the receiver. |
| * |
| * @return a string representation of the event |
| */ |
| public String toString() { |
| String string = super.toString (); |
| return string.substring (0, string.length() - 1) // remove trailing '}' |
| + " detail=" + detail |
| + "}"; |
| } |
| } |