Bug 830 - Add Heuristics for to query whether GLDrawableUtil.swapGLContextAndAllGLEventListener is safe (Doesn't work w/ pre MSAA onscreen drawable)

GLDrawableUtil.isSwapGLContextSafe(..) allows user to query whether 'we think' it's safe
to utilize swapping of GLContext between GLAutoDrawable instances.

Currently known unsafe cases are:
  - between on- and offscreen and one of the following:
    - MSAA involved, or
    - STEREO involved

Enhanced unit tests in this regard:
  - TestGLContextDrawableSwitch02AWT
    - using GLContextDrawableSwitchBase0
  - TestGLContextDrawableSwitch02NEWT
    - using GLContextDrawableSwitchBase0

Utilized safe query for setupPrint(..) action in:
  - AWT GLCanvas
  - AWT GLJPanel
  - NewtCanvasAWT

3 files changed, 70 insertions, 29 deletions

diff --git a/src/jogl/classes/com/jogamp/opengl/util/GLDrawableUtil.java b/src/jogl/classes/com/jogamp/opengl/util/GLDrawableUtil.java
index a2978d6d5..c19bb12e9 100644
--- a/src/jogl/classes/com/jogamp/opengl/util/GLDrawableUtil.java
+++ b/src/jogl/classes/com/jogamp/opengl/util/GLDrawableUtil.java
@@ -149,6 +149,37 @@ public class GLDrawableUtil {
     }
 
     /**
+     * Return a heuristic value whether switching the {@link GLContext} is safe between {@lin GLAutoDrawable}s,
+     * i.e. via {@link #swapGLContext(GLAutoDrawable, GLAutoDrawable)} or {@link #swapGLContextAndAllGLEventListener(GLAutoDrawable, GLAutoDrawable)}.
+     * <p>
+     * Method currently returns <code>false</code> if:
+     * <ul>
+     *   <li>Switching between on- and offscreen and one of the following is <code>true</code>:
+     *     <ul>
+     *       <li>{@link GLCapabilitiesImmutable#getSampleBuffers() MSAA is used}[1], or
+     *       <li>{@link GLCapabilitiesImmutable#getStereo() Stereo is used}
+     *     </ul></li>
+     * </ul>
+     * Otherwise method returns <code>true</code>
+     * </p>
+     * <p>
+     * [1] See Bug 830: swapGLContextAndAllGLEventListener and onscreen MSAA w/ NV/GLX
+     * </p>
+     */
+    public static boolean isSwapGLContextSafe(final GLCapabilitiesImmutable a, final GLCapabilitiesImmutable b) {
+        if( ( a.isOnscreen() && !b.isOnscreen() || !a.isOnscreen() && b.isOnscreen() ) && // switching between on- and offscreen
+            (
+              ( a.getSampleBuffers() || b.getSampleBuffers() ) ||  // MSAA involved
+              ( a.getStereo() || b.getStereo() )                   // Stereo involved
+            )
+          )
+        {
+            return false;
+        } else {
+            return true;
+        }
+    }
+    /**
      * Swaps the {@link GLContext} and all {@link GLEventListener} between {@link GLAutoDrawable} <code>a</code> and <code>b</code>,
      * while preserving it's initialized state, resets the GL-Viewport and issuing {@link GLEventListener#reshape(GLAutoDrawable, int, int, int, int) reshape(..)}.
      * <p>
diff --git a/src/jogl/classes/javax/media/opengl/awt/GLCanvas.java b/src/jogl/classes/javax/media/opengl/awt/GLCanvas.java
index a8aa7382d..4b1d4a7ff 100644
--- a/src/jogl/classes/javax/media/opengl/awt/GLCanvas.java
+++ b/src/jogl/classes/javax/media/opengl/awt/GLCanvas.java
@@ -860,32 +860,35 @@ public class GLCanvas extends Canvas implements AWTGLAutoDrawable, WindowClosing
               printAnimator.remove(GLCanvas.this);
           }
           printGLAD = GLCanvas.this; // _not_ default, shall be replaced by offscreen GLAD
-          final GLCapabilities caps = (GLCapabilities)getChosenGLCapabilities().cloneMutable();
-          final int printNumSamples = printAWTTiles.getNumSamples(caps);
+          final GLCapabilitiesImmutable gladCaps = getChosenGLCapabilities();
+          final int printNumSamples = printAWTTiles.getNumSamples(gladCaps);
           GLDrawable printDrawable = printGLAD.getDelegatedDrawable();
-          final boolean reqNewGLADSamples = printNumSamples != caps.getNumSamples();
+          final boolean reqNewGLADSamples = printNumSamples != gladCaps.getNumSamples();
           final boolean reqNewGLADSize = printAWTTiles.customTileWidth != -1 && printAWTTiles.customTileWidth != printDrawable.getSurfaceWidth() ||
                                          printAWTTiles.customTileHeight != -1 && printAWTTiles.customTileHeight != printDrawable.getSurfaceHeight();
-          final boolean reqNewGLADOnscrn = caps.isOnscreen();
-          // It is desired to use a new offscreen GLAD, however Bug 830 forbids this for AA onscreen context.
-          // Bug 830: swapGLContextAndAllGLEventListener and onscreen MSAA w/ NV/GLX
-          final boolean reqNewGLAD = !caps.getSampleBuffers() && ( reqNewGLADOnscrn || reqNewGLADSamples || reqNewGLADSize );
+          final boolean reqNewGLADOnscrn = gladCaps.isOnscreen();
+
+          final GLCapabilities newGLADCaps = (GLCapabilities)gladCaps.cloneMutable();
+          newGLADCaps.setDoubleBuffered(false);
+          newGLADCaps.setOnscreen(false);
+          if( printNumSamples != newGLADCaps.getNumSamples() ) {
+              newGLADCaps.setSampleBuffers(0 < printNumSamples);
+              newGLADCaps.setNumSamples(printNumSamples);
+          }
+          final boolean reqNewGLADSafe = GLDrawableUtil.isSwapGLContextSafe(gladCaps, newGLADCaps);
+
+          final boolean reqNewGLAD = ( reqNewGLADOnscrn || reqNewGLADSamples || reqNewGLADSize ) && reqNewGLADSafe;
+
           if( DEBUG ) {
-              System.err.println("AWT print.setup: reqNewGLAD "+reqNewGLAD+"[ onscreen "+reqNewGLADOnscrn+", samples "+reqNewGLADSamples+", size "+reqNewGLADSize+"], "+
+              System.err.println("AWT print.setup: reqNewGLAD "+reqNewGLAD+"[ onscreen "+reqNewGLADOnscrn+", samples "+reqNewGLADSamples+", size "+reqNewGLADSize+", safe "+reqNewGLADSafe+"], "+
                                  ", drawableSize "+printDrawable.getSurfaceWidth()+"x"+printDrawable.getSurfaceHeight()+
                                  ", customTileSize "+printAWTTiles.customTileWidth+"x"+printAWTTiles.customTileHeight+
                                  ", scaleMat "+printAWTTiles.scaleMatX+" x "+printAWTTiles.scaleMatY+
                                  ", numSamples "+printAWTTiles.customNumSamples+" -> "+printNumSamples+", printAnimator "+printAnimator);
           }
           if( reqNewGLAD ) {
-              caps.setDoubleBuffered(false);
-              caps.setOnscreen(false);
-              if( printNumSamples != caps.getNumSamples() ) {
-                  caps.setSampleBuffers(0 < printNumSamples);
-                  caps.setNumSamples(printNumSamples);
-              }
-              final GLDrawableFactory factory = GLDrawableFactory.getFactory(caps.getGLProfile());
-              printGLAD = factory.createOffscreenAutoDrawable(null, caps, null,
+              final GLDrawableFactory factory = GLDrawableFactory.getFactory(newGLADCaps.getGLProfile());
+              printGLAD = factory.createOffscreenAutoDrawable(null, newGLADCaps, null,
                       printAWTTiles.customTileWidth != -1 ? printAWTTiles.customTileWidth : DEFAULT_PRINT_TILE_SIZE,
                       printAWTTiles.customTileHeight != -1 ? printAWTTiles.customTileHeight : DEFAULT_PRINT_TILE_SIZE);
               GLDrawableUtil.swapGLContextAndAllGLEventListener(GLCanvas.this, printGLAD);
@@ -896,7 +899,7 @@ public class GLCanvas extends Canvas implements AWTGLAutoDrawable, WindowClosing
           printAWTTiles.renderer.attachAutoDrawable(printGLAD);
           if( DEBUG ) {
               System.err.println("AWT print.setup "+printAWTTiles);
-              System.err.println("AWT print.setup AA "+printNumSamples+", "+caps);
+              System.err.println("AWT print.setup AA "+printNumSamples+", "+newGLADCaps);
               System.err.println("AWT print.setup printGLAD: "+printGLAD.getSurfaceWidth()+"x"+printGLAD.getSurfaceHeight()+", "+printGLAD);
               System.err.println("AWT print.setup printDraw: "+printDrawable.getSurfaceWidth()+"x"+printDrawable.getSurfaceHeight()+", "+printDrawable);
           }
diff --git a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
index 3a1e45440..96f9e455c 100644
--- a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
+++ b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
@@ -712,27 +712,34 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
           }
 
           printGLAD = GLJPanel.this; // default: re-use
-          final GLCapabilities caps = (GLCapabilities)getChosenGLCapabilities().cloneMutable();
-          final int printNumSamples = printAWTTiles.getNumSamples(caps);
+          final GLCapabilitiesImmutable gladCaps = getChosenGLCapabilities();
+          final int printNumSamples = printAWTTiles.getNumSamples(gladCaps);
           GLDrawable printDrawable = printGLAD.getDelegatedDrawable();
-          final boolean reqNewGLADSamples = printNumSamples != caps.getNumSamples();
+          final boolean reqNewGLADSamples = printNumSamples != gladCaps.getNumSamples();
           final boolean reqNewGLADSize = printAWTTiles.customTileWidth != -1 && printAWTTiles.customTileWidth != printDrawable.getSurfaceWidth() ||
                                          printAWTTiles.customTileHeight != -1 && printAWTTiles.customTileHeight != printDrawable.getSurfaceHeight();
-          final boolean reqNewGLAD = reqNewGLADSamples || reqNewGLADSize ;
+
+          final GLCapabilities newGLADCaps = (GLCapabilities)gladCaps.cloneMutable();
+          newGLADCaps.setDoubleBuffered(false);
+          newGLADCaps.setOnscreen(false);
+          if( printNumSamples != newGLADCaps.getNumSamples() ) {
+              newGLADCaps.setSampleBuffers(0 < printNumSamples);
+              newGLADCaps.setNumSamples(printNumSamples);
+          }
+          final boolean reqNewGLADSafe = GLDrawableUtil.isSwapGLContextSafe(gladCaps, newGLADCaps);
+
+          final boolean reqNewGLAD = ( reqNewGLADSamples || reqNewGLADSize ) && reqNewGLADSafe;
+
           if( DEBUG ) {
-              System.err.println("AWT print.setup: reqNewGLAD "+reqNewGLAD+"[ samples "+reqNewGLADSamples+", size "+reqNewGLADSize+"], "+
+              System.err.println("AWT print.setup: reqNewGLAD "+reqNewGLAD+"[ samples "+reqNewGLADSamples+", size "+reqNewGLADSize+", safe "+reqNewGLADSafe+"], "+
                                  ", drawableSize "+printDrawable.getSurfaceWidth()+"x"+printDrawable.getSurfaceHeight()+
                                  ", customTileSize "+printAWTTiles.customTileWidth+"x"+printAWTTiles.customTileHeight+
                                  ", scaleMat "+printAWTTiles.scaleMatX+" x "+printAWTTiles.scaleMatY+
                                  ", numSamples "+printAWTTiles.customNumSamples+" -> "+printNumSamples+", printAnimator "+printAnimator);
           }
           if( reqNewGLAD ) {
-              caps.setDoubleBuffered(false);
-              caps.setOnscreen(false);
-              caps.setSampleBuffers(0 < printNumSamples);
-              caps.setNumSamples(printNumSamples);
-              final GLDrawableFactory factory = GLDrawableFactory.getFactory(caps.getGLProfile());
-              printGLAD = factory.createOffscreenAutoDrawable(null, caps, null,
+              final GLDrawableFactory factory = GLDrawableFactory.getFactory(newGLADCaps.getGLProfile());
+              printGLAD = factory.createOffscreenAutoDrawable(null, newGLADCaps, null,
                       printAWTTiles.customTileWidth != -1 ? printAWTTiles.customTileWidth : DEFAULT_PRINT_TILE_SIZE,
                       printAWTTiles.customTileHeight != -1 ? printAWTTiles.customTileHeight : DEFAULT_PRINT_TILE_SIZE);
               GLDrawableUtil.swapGLContextAndAllGLEventListener(GLJPanel.this, printGLAD);
@@ -743,7 +750,7 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
           printAWTTiles.renderer.attachAutoDrawable(printGLAD);
           if( DEBUG ) {
               System.err.println("AWT print.setup "+printAWTTiles);
-              System.err.println("AWT print.setup AA "+printNumSamples+", "+caps);
+              System.err.println("AWT print.setup AA "+printNumSamples+", "+newGLADCaps);
               System.err.println("AWT print.setup printGLAD: "+printGLAD.getSurfaceWidth()+"x"+printGLAD.getSurfaceHeight()+", "+printGLAD);
               System.err.println("AWT print.setup printDraw: "+printDrawable.getSurfaceWidth()+"x"+printDrawable.getSurfaceHeight()+", "+printDrawable);
           }