Copied JOGL_2_SANDBOX r1957 on to trunk; JOGL_2_SANDBOX branch is now closed

git-svn-id: file:///usr/local/projects/SUN/JOGL/git-svn/svn-server-sync/jogl/trunk@1959 232f8b59-042b-4e1e-8c03-345bb8c30851

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diff --git a/src/jogl/classes/javax/media/opengl/Threading.java b/src/jogl/classes/javax/media/opengl/Threading.java
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+/*
+ * Copyright (c) 2003 Sun Microsystems, Inc. All Rights Reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ * - Redistribution of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * 
+ * - Redistribution in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * 
+ * Neither the name of Sun Microsystems, Inc. or the names of
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ * 
+ * This software is provided "AS IS," without a warranty of any kind. ALL
+ * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
+ * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
+ * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
+ * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
+ * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
+ * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
+ * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
+ * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
+ * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
+ * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
+ * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+ * 
+ * You acknowledge that this software is not designed or intended for use
+ * in the design, construction, operation or maintenance of any nuclear
+ * facility.
+ * 
+ * Sun gratefully acknowledges that this software was originally authored
+ * and developed by Kenneth Bradley Russell and Christopher John Kline.
+ */
+
+package javax.media.opengl;
+
+import com.sun.opengl.impl.*;
+
+/** This API provides access to the threading model for the implementation of 
+    the classes in this package.
+
+    <P>
+
+    OpenGL is specified as a thread-safe API, but in practice there
+    are multithreading-related issues on most, if not all, of the
+    platforms which support it. For example, some OpenGL
+    implementations do not behave well when one context is made
+    current first on one thread, released, and then made current on a
+    second thread, although this is legal according to the OpenGL
+    specification. On other platforms there are other problems.
+
+    <P>
+
+    Due to these limitations, and due to the inherent multithreading
+    in the Java platform (in particular, in the Abstract Window
+    Toolkit), it is often necessary to limit the multithreading 
+    occurring in the typical application using the OpenGL API. 
+
+    <P>
+
+    In the current reference implementation, for instance, multithreading 
+    has been limited by
+    forcing all OpenGL-related work for GLAutoDrawables on to a single
+    thread. In other words, if an application uses only the
+    GLAutoDrawable and GLEventListener callback mechanism, it is
+    guaranteed to have the most correct single-threaded behavior on
+    all platforms.
+
+    <P>
+
+    Applications using the GLContext makeCurrent/release API directly
+    will inherently break this single-threaded model, as these methods
+    require that the OpenGL context be made current on the current
+    thread immediately. For applications wishing to integrate better
+    with an implementation that uses the single-threaded model, this
+    class provides public access to the mechanism used by the implementation.
+
+    <P>
+
+    Users can execute Runnables on the
+    internal thread used for performing OpenGL work, and query whether
+    the current thread is already this thread. Using these mechanisms
+    the user can move work from the current thread on to the internal
+    OpenGL thread if desired.
+
+    <P>
+
+    This class also provides mechanisms for querying whether this
+    internal serialization of OpenGL work is in effect, and a
+    programmatic way of disabling it.  In the current reference 
+    implementation it is enabled by default, although it could be 
+    disabled in the future if OpenGL drivers become more robust on 
+    all platforms.
+
+    <P>
+
+    In addition to specifying programmatically whether the single
+    thread for OpenGL work is enabled, users may switch it on and off
+    using the system property <code>opengl.1thread</code>. Valid values
+    for this system property are:
+
+    <PRE>
+    -Dopengl.1thread=false     Disable single-threading of OpenGL work
+    -Dopengl.1thread=true      Enable single-threading of OpenGL work (default -- on a newly-created worker thread)
+    -Dopengl.1thread=auto      Select default single-threading behavior (currently on)
+    -Dopengl.1thread=awt       Enable single-threading of OpenGL work on AWT event dispatch thread (current default on all
+                                 platforms, and also the default behavior older releases)
+    -Dopengl.1thread=worker    Enable single-threading of OpenGL work on newly-created worker thread (not suitable for Mac
+                                 OS X or X11 platforms, and risky on Windows in applet environments)
+    </PRE>    
+*/
+
+public class Threading {
+
+    /** No reason to ever instantiate this class */
+    private Threading() {}
+
+    /** If an implementation of the javax.media.opengl APIs offers a 
+        multithreading option but the default behavior is single-threading, 
+        this API provides a mechanism for end users to disable single-threading 
+        in this implementation.  Users are strongly discouraged from
+        calling this method unless they are aware of all of the
+        consequences and are prepared to enforce some amount of
+        threading restrictions in their applications. Disabling
+        single-threading, for example, may have unintended consequences
+        on GLAutoDrawable implementations such as GLCanvas, GLJPanel and
+        GLPbuffer. Currently there is no supported way to re-enable it
+        once disabled, partly to discourage careless use of this
+        method. This method should be called as early as possible in an
+        application. */ 
+    public static void disableSingleThreading() {
+        ThreadingImpl.disableSingleThreading();
+    }
+
+    /** Indicates whether OpenGL work is being automatically forced to a
+        single thread in this implementation. */
+    public static boolean isSingleThreaded() {
+        return ThreadingImpl.isSingleThreaded();
+    }
+
+    /** Indicates whether the current thread is the single thread on
+        which this implementation of the javax.media.opengl APIs
+        performs all of its OpenGL-related work. This method should only
+        be called if the single-thread model is in effect. */
+    public static boolean isOpenGLThread() throws GLException {
+        return ThreadingImpl.isOpenGLThread();
+    }
+
+    /** Executes the passed Runnable on the single thread used for all
+        OpenGL work in this javax.media.opengl API implementation. It is
+        not specified exactly which thread is used for this
+        purpose. This method should only be called if the single-thread
+        model is in use and if the current thread is not the OpenGL
+        thread (i.e., if <code>isOpenGLThread()</code> returns
+        false). It is up to the end user to check to see whether the
+        current thread is the OpenGL thread and either execute the
+        Runnable directly or perform the work inside it. */
+    public static void invokeOnOpenGLThread(Runnable r) throws GLException {
+        ThreadingImpl.invokeOnOpenGLThread(r);
+    }
+}