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From-SVN: r102074

libjava/classpath/java/awt/BufferCapabilities.java

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+/* BufferCapabilities.java -- double-buffering capabilities descriptor
+   Copyright (C) 2002, 2005  Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package java.awt;
+
+import java.awt.image.BufferStrategy;
+
+/**
+ * A double-buffering capability descriptor.  This class exposes
+ * details about the double-buffering algorithms used by image
+ * buffers.
+ *
+ * BufferCapabilities represents algorithms that involve at least two
+ * buffers but it can also specify so-called "multi-buffer" schemes
+ * involving more than two buffers.  This class describes the
+ * capabilities of the front and back buffers as well as the results
+ * of "flipping" -- that is, what happens when an image is transferred
+ * from the back buffer to the front buffer.
+ *
+ * Flipping may or may not be supported or may be supported only in
+ * fullscreen mode.  If it is not supported then "blitting" is implied
+ * -- that is, the contents of the back buffer are copied using a fast
+ * block transfer operation from the back buffer to the front buffer.
+ *
+ * The front buffer is the one that is displayed.
+ *
+ * @author Eric Blake (ebb9@email.byu.edu)
+ *
+ * @see BufferStrategy#getCapabilities()
+ * @see GraphicsConfiguration#getBufferCapabilities()
+ *
+ * @since 1.4
+ */
+public class BufferCapabilities implements Cloneable
+{
+  /**
+   * A type-safe enumeration of buffer flipping results.
+   *
+   * @see AttributeValue
+   */
+  public static final class FlipContents extends AttributeValue
+  {
+    /**
+     * The names of the different flipping results.
+     */
+    private static final String[] NAMES
+      = { "undefined", "background", "prior", "copied" };
+
+    /**
+     * The contents of the back buffer are undefined after flipping.
+     */
+    public static final FlipContents UNDEFINED = new FlipContents(0);
+
+    /**
+     * The back buffer is cleared with the background color after
+     * flipping.
+     */
+    public static final FlipContents BACKGROUND = new FlipContents(1);
+
+    /**
+     * The back buffer contains the pre-flipping contents of the front
+     * buffer after flipping.  In other words a true "flip" has been
+     * performed.
+     */
+    public static final FlipContents PRIOR = new FlipContents(2);
+
+    /**
+     * The back buffer has the same contents as the front buffer after
+     * flipping.
+     */
+    public static final FlipContents COPIED = new FlipContents(3);
+
+    /**
+     * Create a new flipping result descriptor.
+     *
+     * @param value the enumeration value
+     */
+    private FlipContents(int value)
+    {
+      super(value, NAMES);
+    }
+  }
+
+  /**
+   * Front buffer capabilities descriptor.
+   */
+  private final ImageCapabilities front;
+
+  /**
+   * Back buffer capabilities descriptor.
+   */
+  private final ImageCapabilities back;
+
+  /**
+   * Describes the results of a "flip" operation.
+   */
+  private final FlipContents flip;
+
+  /**
+   * Creates a buffer capabilities object.
+   *
+   * @param frontCaps front buffer capabilities descriptor
+   * @param backCaps back buffer capabilities descriptor
+   * @param flip the results of a flip operation or null if
+   * flipping is not supported
+   *
+   * @exception IllegalArgumentException if frontCaps or backCaps is
+   * null
+   */
+  public BufferCapabilities(ImageCapabilities frontCaps,
+			    ImageCapabilities backCaps,
+                            FlipContents flip)
+  {
+    if (frontCaps ==  null || backCaps == null)
+      throw new IllegalArgumentException();
+    this.front = frontCaps;
+    this.back = backCaps;
+    this.flip = flip;
+  }
+
+  /**
+   * Retrieve the front buffer's image capabilities.
+   *
+   * @return the front buffer's image capabilities
+   */
+  public ImageCapabilities getFrontBufferCapabilities()
+  {
+    return front;
+  }
+
+  /**
+   * Retrieve the back buffer's image capabilities.
+   *
+   * @return the back buffer's image capabilities
+   */
+  public ImageCapabilities getBackBufferCapabilities()
+  {
+    return back;
+  }
+
+  /**
+   * Return whether or not flipping is supported.
+   *
+   * @return true if flipping is supported, false otherwise
+   */
+  public boolean isPageFlipping()
+  {
+    return flip != null;
+  }
+
+  /**
+   * Retrieve the result of a flipping operation.  If this method
+   * returns null then flipping is not supported.  This implies that
+   * "blitting", a fast block transfer, is used to copy the contents
+   * of the back buffer to the front buffer.  Other possible return
+   * values are:
+   * <ul>
+   *   <li><code>FlipContents.UNDEFINED</code> the contents of the
+   *   back buffer are undefined after flipping.</li>
+   *   <li><code>FlipContents.BACKGROUND</code> the contents of the
+   *   back buffer are cleared to the background color after
+   *   flipping.</li>
+   *   <li><code>FlipContents.PRIOR</code> the back buffer contains
+   *   the pre-flipping contents of the front * buffer after
+   *   flipping.</li>
+   *   <li><code>FlipContents.COPIED</code> the back buffer has the
+   *   same contents as the front buffer after flipping.</li>
+   * </ul>
+   *
+   * @return the result of a flipping operation or null if flipping is
+   * not supported
+   */
+  public FlipContents getFlipContents()
+  {
+    return flip;
+  }
+
+  /**
+   * Returns true if flipping is only supported in fullscreen mode.
+   *
+   * @return true if flipping is only supported in fullscreen mode,
+   * false otherwise
+   */
+  public boolean isFullScreenRequired()
+  {
+    return true;
+  }
+
+  /**
+   * Returns true if flipping can involve more than two buffers.  One
+   * or more intermediate buffers may be available in addition to the
+   * front and back buffers.
+   *
+   * @return true if there are more than two buffers available for
+   * flipping, false otherwise
+   */
+  public boolean isMultiBufferAvailable()
+  {
+    return false;
+  }
+
+  /**
+   * Clone this buffering capability descriptor.
+   *
+   * @return a clone of this buffer capability descriptor
+   */
+  public Object clone()
+  {
+    try
+      {
+        return super.clone();
+      }
+    catch (CloneNotSupportedException e)
+      {
+        throw (Error) new InternalError().initCause(e);
+      }
+  }
+}