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) 2000, 2011 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
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
     */
    @Override
    public String toString() {
        String string = super.toString();
        return string.substring(0, string.length() - 1) // remove trailing '}'
                + " character='" + ((character == 0) ? "\\0" : String.valueOf(character)) + "'=0x"
                + Integer.toHexString(character) + " keyCode=0x" + Integer.toHexString(keyCode) + " keyLocation=0x"
                + Integer.toHexString(keyLocation) + " stateMask=0x" + Integer.toHexString(stateMask) + " doit="
                + doit + "}";
    }
}