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/*******************************************************************************
* 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.graphics;
import org.eclipse.swt.*;
/**
* This class is the abstract superclass of all graphics resource objects.
* Resources created by the application must be disposed.
* <p>
* IMPORTANT: This class is intended to be subclassed <em>only</em>
* within the SWT implementation. However, it has not been marked
* final to allow those outside of the SWT development team to implement
* patched versions of the class in order to get around specific
* limitations in advance of when those limitations can be addressed
* by the team. Any class built using subclassing to access the internals
* of this class will likely fail to compile or run between releases and
* may be strongly platform specific. Subclassing should not be attempted
* without an intimate and detailed understanding of the workings of the
* hierarchy. No support is provided for user-written classes which are
* implemented as subclasses of this class.
* </p>
*
* @see #dispose
* @see #isDisposed
* @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
*
* @since 3.1
*/
public abstract class Resource {
/**
* the device where this resource was created
*/
Device device;
public Resource() {
}
Resource(Device device) {
if (device == null) device = Device.getDevice();
if (device == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
this.device = device;
}
void destroy() {
}
/**
* Disposes of the operating system resources associated with
* this resource. Applications must dispose of all resources
* which they allocate.
* This method does nothing if the resource is already disposed.
*/
public void dispose() {
if (device == null) return;
if (device.isDisposed()) return;
destroy();
if (device.tracking) device.dispose_Object(this);
device = null;
}
/**
* Returns the <code>Device</code> where this resource was
* created.
*
* @return <code>Device</code> the device of the receiver
*
* @since 3.2
*/
public Device getDevice() {
Device device = this.device;
if (device == null || isDisposed ()) SWT.error (SWT.ERROR_GRAPHIC_DISPOSED);
return device;
}
void init() {
if (device.tracking) device.new_Object(this);
}
/**
* Returns <code>true</code> if the resource has been disposed,
* and <code>false</code> otherwise.
* <p>
* This method gets the dispose state for the resource.
* When a resource has been disposed, it is an error to
* invoke any other method (except {@link #dispose()}) using the resource.
*
* @return <code>true</code> when the resource is disposed and <code>false</code> otherwise
*/
public abstract boolean isDisposed();
}
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