254 lines
7.5 KiB
Java
254 lines
7.5 KiB
Java
/* BufferCapabilities.java -- double-buffering capabilities descriptor
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Copyright (C) 2002, 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt;
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import java.awt.image.BufferStrategy;
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/**
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* A double-buffering capability descriptor. This class exposes
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* details about the double-buffering algorithms used by image
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* buffers.
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*
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* BufferCapabilities represents algorithms that involve at least two
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* buffers but it can also specify so-called "multi-buffer" schemes
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* involving more than two buffers. This class describes the
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* capabilities of the front and back buffers as well as the results
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* of "flipping" -- that is, what happens when an image is transferred
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* from the back buffer to the front buffer.
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*
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* Flipping may or may not be supported or may be supported only in
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* fullscreen mode. If it is not supported then "blitting" is implied
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* -- that is, the contents of the back buffer are copied using a fast
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* block transfer operation from the back buffer to the front buffer.
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*
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* The front buffer is the one that is displayed.
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*
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* @author Eric Blake (ebb9@email.byu.edu)
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*
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* @see BufferStrategy#getCapabilities()
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* @see GraphicsConfiguration#getBufferCapabilities()
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*
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* @since 1.4
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*/
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public class BufferCapabilities implements Cloneable
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{
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/**
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* A type-safe enumeration of buffer flipping results.
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*
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* @see AttributeValue
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*/
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public static final class FlipContents extends AttributeValue
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{
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/**
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* The names of the different flipping results.
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*/
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private static final String[] NAMES
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= { "undefined", "background", "prior", "copied" };
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/**
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* The contents of the back buffer are undefined after flipping.
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*/
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public static final FlipContents UNDEFINED = new FlipContents(0);
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/**
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* The back buffer is cleared with the background color after
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* flipping.
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*/
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public static final FlipContents BACKGROUND = new FlipContents(1);
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/**
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* The back buffer contains the pre-flipping contents of the front
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* buffer after flipping. In other words a true "flip" has been
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* performed.
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*/
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public static final FlipContents PRIOR = new FlipContents(2);
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/**
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* The back buffer has the same contents as the front buffer after
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* flipping.
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*/
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public static final FlipContents COPIED = new FlipContents(3);
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/**
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* Create a new flipping result descriptor.
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*
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* @param value the enumeration value
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*/
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private FlipContents(int value)
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{
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super(value, NAMES);
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}
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}
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/**
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* Front buffer capabilities descriptor.
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*/
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private final ImageCapabilities front;
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/**
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* Back buffer capabilities descriptor.
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*/
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private final ImageCapabilities back;
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/**
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* Describes the results of a "flip" operation.
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*/
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private final FlipContents flip;
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/**
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* Creates a buffer capabilities object.
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*
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* @param frontCaps front buffer capabilities descriptor
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* @param backCaps back buffer capabilities descriptor
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* @param flip the results of a flip operation or null if
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* flipping is not supported
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*
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* @exception IllegalArgumentException if frontCaps or backCaps is
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* null
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*/
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public BufferCapabilities(ImageCapabilities frontCaps,
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ImageCapabilities backCaps,
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FlipContents flip)
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{
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if (frontCaps == null || backCaps == null)
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throw new IllegalArgumentException();
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this.front = frontCaps;
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this.back = backCaps;
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this.flip = flip;
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}
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/**
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* Retrieve the front buffer's image capabilities.
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*
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* @return the front buffer's image capabilities
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*/
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public ImageCapabilities getFrontBufferCapabilities()
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{
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return front;
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}
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/**
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* Retrieve the back buffer's image capabilities.
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*
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* @return the back buffer's image capabilities
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*/
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public ImageCapabilities getBackBufferCapabilities()
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{
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return back;
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}
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/**
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* Return whether or not flipping is supported.
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*
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* @return true if flipping is supported, false otherwise
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*/
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public boolean isPageFlipping()
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{
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return flip != null;
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}
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/**
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* Retrieve the result of a flipping operation. If this method
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* returns null then flipping is not supported. This implies that
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* "blitting", a fast block transfer, is used to copy the contents
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* of the back buffer to the front buffer. Other possible return
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* values are:
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* <ul>
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* <li><code>FlipContents.UNDEFINED</code> the contents of the
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* back buffer are undefined after flipping.</li>
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* <li><code>FlipContents.BACKGROUND</code> the contents of the
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* back buffer are cleared to the background color after
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* flipping.</li>
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* <li><code>FlipContents.PRIOR</code> the back buffer contains
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* the pre-flipping contents of the front * buffer after
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* flipping.</li>
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* <li><code>FlipContents.COPIED</code> the back buffer has the
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* same contents as the front buffer after flipping.</li>
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* </ul>
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*
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* @return the result of a flipping operation or null if flipping is
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* not supported
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*/
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public FlipContents getFlipContents()
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{
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return flip;
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}
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/**
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* Returns true if flipping is only supported in fullscreen mode.
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*
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* @return true if flipping is only supported in fullscreen mode,
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* false otherwise
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*/
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public boolean isFullScreenRequired()
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{
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return true;
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}
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/**
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* Returns true if flipping can involve more than two buffers. One
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* or more intermediate buffers may be available in addition to the
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* front and back buffers.
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*
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* @return true if there are more than two buffers available for
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* flipping, false otherwise
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*/
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public boolean isMultiBufferAvailable()
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{
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return false;
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}
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/**
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* Clone this buffering capability descriptor.
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*
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* @return a clone of this buffer capability descriptor
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*/
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public Object clone()
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{
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try
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{
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return super.clone();
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}
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catch (CloneNotSupportedException e)
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{
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throw (Error) new InternalError().initCause(e);
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}
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}
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}
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