https://openjdk.java.net/ 
/*
 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.awt;


Capabilities and properties of buffers.

Author:Michael Martak
See Also:
Since:1.4
/**
 * Capabilities and properties of buffers.
 *
 * @see java.awt.image.BufferStrategy#getCapabilities()
 * @see GraphicsConfiguration#getBufferCapabilities
 * @author Michael Martak
 * @since 1.4
 */
public class BufferCapabilities implements Cloneable {

    private ImageCapabilities frontCaps;
    private ImageCapabilities backCaps;
    private FlipContents flipContents;

    
Creates a new object for specifying buffering capabilities

Params:
  • frontCaps – the capabilities of the front buffer; cannot be null
  • backCaps – the capabilities of the back and intermediate buffers; cannot be null
  • flipContents – the contents of the back buffer after page-flipping, null if page flipping is not used (implies blitting)
Throws:
/**
     * Creates a new object for specifying buffering capabilities
     * @param frontCaps the capabilities of the front buffer; cannot be
     * {@code null}
     * @param backCaps the capabilities of the back and intermediate buffers;
     * cannot be {@code null}
     * @param flipContents the contents of the back buffer after page-flipping,
     * {@code null} if page flipping is not used (implies blitting)
     * @exception IllegalArgumentException if frontCaps or backCaps are
     * {@code null}
     */
    public BufferCapabilities(ImageCapabilities frontCaps,
        ImageCapabilities backCaps, FlipContents flipContents) {
        if (frontCaps == null || backCaps == null) {
            throw new IllegalArgumentException(
                "Image capabilities specified cannot be null");
        }
        this.frontCaps = frontCaps;
        this.backCaps = backCaps;
        this.flipContents = flipContents;
    }

    
Returns:the image capabilities of the front (displayed) buffer
/**
     * @return the image capabilities of the front (displayed) buffer
     */
    public ImageCapabilities getFrontBufferCapabilities() {
        return frontCaps;
    }

    
Returns:the image capabilities of all back buffers (intermediate buffers
are considered back buffers)
/**
     * @return the image capabilities of all back buffers (intermediate buffers
     * are considered back buffers)
     */
    public ImageCapabilities getBackBufferCapabilities() {
        return backCaps;
    }

    
Returns:whether or not the buffer strategy uses page flipping; a set of buffers that uses page flipping can swap the contents internally between the front buffer and one or more back buffers by switching the video pointer (or by copying memory internally). A non-flipping set of buffers uses blitting to copy the contents from one buffer to another; when this is the case, getFlipContents returns null
/**
     * @return whether or not the buffer strategy uses page flipping; a set of
     * buffers that uses page flipping
     * can swap the contents internally between the front buffer and one or
     * more back buffers by switching the video pointer (or by copying memory
     * internally).  A non-flipping set of
     * buffers uses blitting to copy the contents from one buffer to
     * another; when this is the case, {@code getFlipContents} returns
     * {@code null}
     */
    public boolean isPageFlipping() {
        return (getFlipContents() != null);
    }

    
See Also:
Returns:the resulting contents of the back buffer after page-flipping. This value is null when the isPageFlipping returns false, implying blitting. It can be one of FlipContents.UNDEFINED (the assumed default), FlipContents.BACKGROUND, FlipContents.PRIOR, or FlipContents.COPIED.
/**
     * @return the resulting contents of the back buffer after page-flipping.
     * This value is {@code null} when the {@code isPageFlipping}
     * returns {@code false}, implying blitting.  It can be one of
     * {@code FlipContents.UNDEFINED}
     * (the assumed default), {@code FlipContents.BACKGROUND},
     * {@code FlipContents.PRIOR}, or
     * {@code FlipContents.COPIED}.
     * @see #isPageFlipping
     * @see FlipContents#UNDEFINED
     * @see FlipContents#BACKGROUND
     * @see FlipContents#PRIOR
     * @see FlipContents#COPIED
     */
    public FlipContents getFlipContents() {
        return flipContents;
    }

    
See Also:
Returns:whether page flipping is only available in full-screen mode. If this is true, full-screen exclusive mode is required for page-flipping.
/**
     * @return whether page flipping is only available in full-screen mode.  If this
     * is {@code true}, full-screen exclusive mode is required for
     * page-flipping.
     * @see #isPageFlipping
     * @see GraphicsDevice#setFullScreenWindow
     */
    public boolean isFullScreenRequired() {
        return false;
    }

    
See Also:
Returns:whether or not
page flipping can be performed using more than two buffers (one or more
intermediate buffers as well as the front and back buffer).
/**
     * @return whether or not
     * page flipping can be performed using more than two buffers (one or more
     * intermediate buffers as well as the front and back buffer).
     * @see #isPageFlipping
     */
    public boolean isMultiBufferAvailable() {
        return false;
    }

    
Returns:a copy of this BufferCapabilities object.
/**
     * @return a copy of this BufferCapabilities object.
     */
    public Object clone() {
        try {
            return super.clone();
        } catch (CloneNotSupportedException e) {
            // Since we implement Cloneable, this should never happen
            throw new InternalError(e);
        }
    }

    // Inner class FlipContents
    
A type-safe enumeration of the possible back buffer contents after
page-flipping

Since:1.4
/**
     * A type-safe enumeration of the possible back buffer contents after
     * page-flipping
     * @since 1.4
     */
    public static final class FlipContents extends AttributeValue {

        private static int I_UNDEFINED = 0;
        private static int I_BACKGROUND = 1;
        private static int I_PRIOR = 2;
        private static int I_COPIED = 3;

        private static final String[] NAMES =
            { "undefined", "background", "prior", "copied" };

        
When flip contents are UNDEFINED, the contents of the back buffer are undefined after flipping. 
See Also:
/**
         * When flip contents are {@code UNDEFINED}, the
         * contents of the back buffer are undefined after flipping.
         * @see #isPageFlipping
         * @see #getFlipContents
         * @see #BACKGROUND
         * @see #PRIOR
         * @see #COPIED
         */
        public static final FlipContents UNDEFINED =
            new FlipContents(I_UNDEFINED);

        
When flip contents are BACKGROUND, the contents of the back buffer are cleared with the background color after flipping. 
See Also:
/**
         * When flip contents are {@code BACKGROUND}, the
         * contents of the back buffer are cleared with the background color after
         * flipping.
         * @see #isPageFlipping
         * @see #getFlipContents
         * @see #UNDEFINED
         * @see #PRIOR
         * @see #COPIED
         */
        public static final FlipContents BACKGROUND =
            new FlipContents(I_BACKGROUND);

        
When flip contents are PRIOR, the contents of the back buffer are the prior contents of the front buffer (a true page flip). 
See Also:
/**
         * When flip contents are {@code PRIOR}, the
         * contents of the back buffer are the prior contents of the front buffer
         * (a true page flip).
         * @see #isPageFlipping
         * @see #getFlipContents
         * @see #UNDEFINED
         * @see #BACKGROUND
         * @see #COPIED
         */
        public static final FlipContents PRIOR =
            new FlipContents(I_PRIOR);

        
When flip contents are COPIED, the contents of the back buffer are copied to the front buffer when flipping. 
See Also:
/**
         * When flip contents are {@code COPIED}, the
         * contents of the back buffer are copied to the front buffer when
         * flipping.
         * @see #isPageFlipping
         * @see #getFlipContents
         * @see #UNDEFINED
         * @see #BACKGROUND
         * @see #PRIOR
         */
        public static final FlipContents COPIED =
            new FlipContents(I_COPIED);

        private FlipContents(int type) {
            super(type, NAMES);
        }

    } // Inner class FlipContents

}