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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package sun.java2d;

import sun.awt.image.SunVolatileImage;
import sun.awt.image.VolatileSurfaceManager;

This factory creates platform specific VolatileSurfaceManager
implementations.
There are two platform specific SurfaceManagerFactories in OpenJDK,
UnixSurfaceManagerFactory and WindowsSurfaceManagerFactory.
The actually used SurfaceManagerFactory is set by the respective platform
GraphicsEnvironment implementations in the static initializer.
/**
 * This factory creates platform specific VolatileSurfaceManager
 * implementations.
 *
 * There are two platform specific SurfaceManagerFactories in OpenJDK,
 * UnixSurfaceManagerFactory and WindowsSurfaceManagerFactory.
 * The actually used SurfaceManagerFactory is set by the respective platform
 * GraphicsEnvironment implementations in the static initializer.
 */
public abstract class SurfaceManagerFactory {

    
The single shared instance.
/**
     * The single shared instance.
     */
    private static SurfaceManagerFactory instance;

    
Returns the surface manager factory instance. This returns a factory that has been set by setInstance(SurfaceManagerFactory). 
Returns:
the surface manager factory/**
     * Returns the surface manager factory instance. This returns a factory
     * that has been set by {@link #setInstance(SurfaceManagerFactory)}.
     *
     * @return the surface manager factory
     */
    public synchronized static SurfaceManagerFactory getInstance() {

        if (instance == null) {
            throw new IllegalStateException("No SurfaceManagerFactory set.");
        }
        return instance;
    }

    
Sets the surface manager factory. This may only be called once, and it may not be set back to null when the factory is already instantiated. 
Params:
factory – the factory to set/**
     * Sets the surface manager factory. This may only be called once, and it
     * may not be set back to {@code null} when the factory is already
     * instantiated.
     *
     * @param factory the factory to set
     */
    public synchronized static void setInstance(SurfaceManagerFactory factory) {

        if (factory == null) {
            // We don't want to allow setting this to null at any time.
            throw new IllegalArgumentException("factory must be non-null");
        }

        if (instance != null) {
            // We don't want to re-set the instance at any time.
            throw new IllegalStateException("The surface manager factory is already initialized");
        }

        instance = factory;
    }

    
Creates a new instance of a VolatileSurfaceManager given any
arbitrary SunVolatileImage.  An optional context Object can be supplied
as a way for the caller to pass pipeline-specific context data to
the VolatileSurfaceManager (such as a backbuffer handle, for example).
/**
     * Creates a new instance of a VolatileSurfaceManager given any
     * arbitrary SunVolatileImage.  An optional context Object can be supplied
     * as a way for the caller to pass pipeline-specific context data to
     * the VolatileSurfaceManager (such as a backbuffer handle, for example).
     */
     public abstract VolatileSurfaceManager
         createVolatileManager(SunVolatileImage image, Object context);
}