KeyEvent.java

/*******************************************************************************
 * Copyright (c) 2000, 2009, 2012 IBM Corporation, Gerhardt Informatics Kft. 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
 *     Gerhardt Informatics Kft. - GEFGWT port
 *******************************************************************************/
package org.eclipse.swt.events;

import org.eclipse.swt.widgets.Event;

/**
 * Instances of this class are sent as a result of keys being pressed and
 * released on the keyboard.
 * <p>
 * When a key listener is added to a control, the control will take part in
 * widget traversal. By default, all traversal keys (such as the tab key and so
 * on) are delivered to the control. In order for a control to take part in
 * traversal, it should listen for traversal events. Otherwise, the user can
 * traverse into a control but not out. Note that native controls such as table
 * and tree implement key traversal in the operating system. It is not necessary
 * to add traversal listeners for these controls, unless you want to override
 * the default traversal.
 * </p>
 * 
 * @see KeyListener
 * @see TraverseListener
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further
 *      information</a>
 */

public class KeyEvent extends TypedEvent {

	/**
	 * the character represented by the key that was typed. This is the final
	 * character that results after all modifiers have been applied. For
	 * example, when the user types Ctrl+A, the character value is 0x01. It is
	 * important that applications do not attempt to modify the character value
	 * based on a stateMask (such as SWT.CTRL) or the resulting character will
	 * not be correct.
	 */
	public char character;

	/**
	 * the key code of the key that was typed, as defined by the key code
	 * constants in class <code>SWT</code>. When the character field of the
	 * event is ambiguous, this field contains the unicode value of the original
	 * character. For example, typing Ctrl+M or Return both result in the
	 * character '\r' but the keyCode field will also contain '\r' when Return
	 * was typed.
	 * 
	 * @see org.eclipse.swt.SWT
	 */
	public int keyCode;

	/**
	 * depending on the event, the location of key specified by the keyCode or
	 * character. The possible values for this field are <code>SWT.LEFT</code>,
	 * <code>SWT.RIGHT</code>, <code>SWT.KEYPAD</code>, or <code>SWT.NONE</code>
	 * representing the main keyboard area.
	 * <p>
	 * The location field can be used to differentiate key events that have the
	 * same key code and character but are generated by different keys on the
	 * keyboard. For example, a key down event with the key code equal to
	 * SWT.SHIFT can be generated by the left and the right shift keys on the
	 * keyboard.
	 * </p>
	 * <p>
	 * The location field can only be used to determine the location of the key
	 * code or character in the current event. It does not include information
	 * about the location of modifiers in the state mask.
	 * </p>
	 * 
	 * @see org.eclipse.swt.SWT#LEFT
	 * @see org.eclipse.swt.SWT#RIGHT
	 * @see org.eclipse.swt.SWT#KEYPAD
	 * 
	 * @since 3.6
	 */
	public int keyLocation;

	/**
	 * the state of the keyboard modifier keys and mouse masks at the time the
	 * event was generated.
	 * 
	 * @see org.eclipse.swt.SWT#MODIFIER_MASK
	 * @see org.eclipse.swt.SWT#BUTTON_MASK
	 */
	public int stateMask;

	/**
	 * A flag indicating whether the operation should be allowed. Setting this
	 * field to <code>false</code> will cancel the operation.
	 */
	public boolean doit;

	static final long serialVersionUID = 3256442491011412789L;

	/**
	 * 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 KeyEvent(Event e) {
		super(e);
		this.character = e.character;
		this.keyCode = e.keyCode;
		this.keyLocation = e.keyLocation;
		this.stateMask = e.stateMask;
		this.doit = e.doit;
	}

	/**
	 * 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 '}'
				+ " character='"
				+ ((character == 0) ? "\\0" : "" + character)
				+ "'" + " keyCode=" + keyCode + " keyLocation="
				+ keyLocation
				+ " stateMask=" + stateMask + " doit=" + doit + "}";
	}
}