org.eclipse.swt.events.KeyEvent.java Source code

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Here is the source code for org.eclipse.swt.events.KeyEvent.java

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/*******************************************************************************
 * Copyright (c) 2008, 2012 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.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>
 *
 * <p><strong>IMPORTANT:</strong> All <code>public static</code> members of
 * this class are <em>not</em> part of the RWT public API. They are marked
 * public only so that they can be shared within the packages provided by RWT.
 * They should never be accessed from application code.
 * </p>
 *
 * @see KeyListener
 * @see TraverseListener
 *
 * @since 1.2
 */
public class KeyEvent extends TypedEvent {

    private static final long serialVersionUID = 1L;

    /**
     * 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;

    /**
     * the state of the keyboard modifier keys at the time the event was
     * generated, as defined by the key code constants in class <code>SWT</code>.
     *
     * @see org.eclipse.swt.SWT
     */
    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;

    /**
     * Constructs a new instance of this class based on the information in the
     * given untyped event.
     *
     * @param event the untyped event containing the information
     */
    public KeyEvent(Event event) {
        super(event);
        character = event.character;
        keyCode = event.keyCode;
        stateMask = event.stateMask;
        doit = event.doit;
    }

    /**
     * Returns a string containing a concise, human-readable description of the
     * receiver.
     *
     * @return a string representation of the event
     */
    @Override
    public String toString() {
        String string = super.toString();
        return string.substring(0, string.length() - 1) // remove trailing '}'
                + " character='" + ((character == 0) ? "\\0" : "" + character) + "'" + " keyCode=" + keyCode
                + " stateMask=" + stateMask + " doit=" + doit + "}";
    }

}