org.eclipse.swt.graphics.Cursor.java Source code

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Here is the source code for org.eclipse.swt.graphics.Cursor.java

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/*******************************************************************************
 * Copyright (c) 2008, 2015 Innoopract Informationssysteme GmbH.
 * 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.graphics;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTError;

/**
 * Instances of this class manage operating system resources that specify the
 * appearance of the on-screen pointer.
 *
 * <p>To obtain cursors, it is recommended to use one of the
 * <code>getSystemCursor</code> method from class <code>Display</code>.
 * </p>
 *
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>
 *   CURSOR_ARROW, CURSOR_WAIT, CURSOR_CROSS, CURSOR_APPSTARTING, CURSOR_HELP,
 *   CURSOR_SIZEALL, CURSOR_SIZENESW, CURSOR_SIZENS, CURSOR_SIZENWSE, CURSOR_SIZEWE,
 *   CURSOR_SIZEN, CURSOR_SIZES, CURSOR_SIZEE, CURSOR_SIZEW, CURSOR_SIZENE, CURSOR_SIZESE,
 *   CURSOR_SIZESW, CURSOR_SIZENW, CURSOR_UPARROW, CURSOR_IBEAM, CURSOR_NO, CURSOR_HAND
 * </dd>
 * </dl>
 * <p>
 * Note: Only one of the above styles may be specified.
 * </p>
 *
 * @since 1.2
 */
public class Cursor extends Resource {

    private final int value;

    // used by ResourceFactory#getCursor()
    private Cursor(int style) {
        super(null);
        checkStyle(style);
        value = style;
    }

    /**
     * Constructs a new cursor given a device and a style
     * constant describing the desired cursor appearance.
     * <p>
     * You must dispose the cursor when it is no longer required.
     * </p>
     * NOTE:
     * It is recommended to use {@link org.eclipse.swt.widgets.Display#getSystemCursor(int)}
     * instead of using this constructor. This way you can avoid the
     * overhead of disposing the Cursor resource.
     *
     * @param device the device on which to allocate the cursor
     * @param style the style of cursor to allocate
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
     *    <li>ERROR_INVALID_ARGUMENT - when an unknown style is specified</li>
     * </ul>
     * @exception SWTError <ul>
     *    <li>ERROR_NO_HANDLES - if a handle could not be obtained for cursor creation</li>
     * </ul>
     *
     * @see SWT#CURSOR_ARROW
     * @see SWT#CURSOR_WAIT
     * @see SWT#CURSOR_CROSS
     * @see SWT#CURSOR_APPSTARTING
     * @see SWT#CURSOR_HELP
     * @see SWT#CURSOR_SIZEALL
     * @see SWT#CURSOR_SIZENESW
     * @see SWT#CURSOR_SIZENS
     * @see SWT#CURSOR_SIZENWSE
     * @see SWT#CURSOR_SIZEWE
     * @see SWT#CURSOR_SIZEN
     * @see SWT#CURSOR_SIZES
     * @see SWT#CURSOR_SIZEE
     * @see SWT#CURSOR_SIZEW
     * @see SWT#CURSOR_SIZENE
     * @see SWT#CURSOR_SIZESE
     * @see SWT#CURSOR_SIZESW
     * @see SWT#CURSOR_SIZENW
     * @see SWT#CURSOR_UPARROW
     * @see SWT#CURSOR_IBEAM
     * @see SWT#CURSOR_NO
     * @see SWT#CURSOR_HAND
     * @see org.eclipse.swt.widgets.Display#getSystemCursor(int)
     *
     * @since 1.3
     */
    public Cursor(Device device, int style) {
        super(checkDevice(device));
        checkStyle(style);
        value = style;
    }

    /**
     * Compares the argument to the receiver, and returns true
     * if they represent the <em>same</em> object using a class
     * specific comparison.
     *
     * @param object the object to compare with this object
     * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise
     *
     * @see #hashCode
     */
    @Override
    public boolean equals(Object object) {
        boolean result;
        if (object == this) {
            result = true;
        } else if (object instanceof Cursor) {
            Cursor cursor = (Cursor) object;
            result = cursor.value == value;
        } else {
            result = false;
        }
        return result;
    }

    /**
     * Returns an integer hash code for the receiver. Any two
     * objects that return <code>true</code> when passed to
     * <code>equals</code> must return the same value for this
     * method.
     *
     * @return the receiver's hash
     *
     * @see #equals
     */
    @Override
    public int hashCode() {
        return 101 * value;
    }

    /**
     * Returns a string containing a concise, human-readable
     * description of the receiver.
     *
     * @return a string representation of the receiver
     */
    @Override
    public String toString() {
        String result;
        if (isDisposed()) {
            result = "Cursor {*DISPOSED*}";
        } else {
            result = "Cursor {" + value + "}";
        }
        return result;
    }

    private static void checkStyle(int style) {
        switch (style) {
        case SWT.CURSOR_ARROW:
        case SWT.CURSOR_WAIT:
        case SWT.CURSOR_APPSTARTING:
        case SWT.CURSOR_CROSS:
        case SWT.CURSOR_HELP:
        case SWT.CURSOR_SIZEALL:
        case SWT.CURSOR_SIZENESW:
        case SWT.CURSOR_SIZENS:
        case SWT.CURSOR_SIZENWSE:
        case SWT.CURSOR_SIZEWE:
        case SWT.CURSOR_SIZEN:
        case SWT.CURSOR_SIZES:
        case SWT.CURSOR_SIZEE:
        case SWT.CURSOR_SIZEW:
        case SWT.CURSOR_SIZENE:
        case SWT.CURSOR_SIZESE:
        case SWT.CURSOR_SIZESW:
        case SWT.CURSOR_SIZENW:
        case SWT.CURSOR_IBEAM:
        case SWT.CURSOR_HAND:
        case SWT.CURSOR_UPARROW:
        case SWT.CURSOR_NO:
            break;
        default:
            SWT.error(SWT.ERROR_INVALID_ARGUMENT);
        }
    }
}