Bug 975 - GLJPanel's OffscreenDrawable shall not double swap - Use default auto-swap mechanims

Refines commit 908ebd99d1eb57ce773a1fdd67c76886da86b9e6

Note that the test case decide whether to auto-swap (after read-pixels)
or not auto-swap (manual swap before read-pixels).

See UITestCase.swapBuffersBeforeRead(GLCapabilitiesImmutable chosenCaps):
   Determines whether the chosen GLCapabilitiesImmutable requires a swap-buffers before reading pixels.

   Usually one uses the default-read-buffer, i.e. GL.GL_FRONT for single-buffer
   and GL.GL_BACK for double-buffer GLDrawables
   and GL.GL_COLOR_ATTACHMENT0 for offscreen framebuffer objects.
   Here swap-buffers shall happen after calling reading pixels, the default.

   However, multisampling offscreen GLFBODrawables utilize swap-buffers to downsample
   the multisamples into the readable sampling sink.
   In this case, we require a swap-buffers before reading pixels.

   Returns:  chosenCaps.isFBO() && chosenCaps.getSampleBuffers()

+++

- GLJPanel:
  - Remove SurfaceUpdatedListener mechanism in favor of
    default auto-swap-buffer via GLDrawableHelper.
    This removes complexity.

  - postGL does not need to perform explicit swapBuffer operation,
    but rely on GLDrawableHelper and the default mechanism.
    This is also compatible w/ J2D backend.

  - Use GLDrawableHelper for setAutoSwapBufferMode(..) and getAutoSwapBufferMode()

+++

UnitTests:

- UITestCase:
  - Add 'boolean swapBuffersBeforeRead(GLCapabilitiesImmutable chosenCaps)'
    to determine whether swapBuffers() must occure before read-pixels. See above.

- GLReadBuffer00Base*
  - remove explicit addSnapshotGLEL/removeSnapshotGLEL

  - add TextRendererGLEL, to display frame-count and -dimension

  - SnapshotGLEL*
    - simply toggle auto-swap in their init(..) and dispose(..) method!

    - clear back-buffer if 'swapBuffersBeforeRead'
      to test whether the right buffer is being used for read-pixels.

1 files changed, 7 insertions, 23 deletions

diff --git a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
index 66a757d10..c80b405b5 100644
--- a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
+++ b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
@@ -60,7 +60,6 @@ import java.util.List;
 
 import javax.media.nativewindow.AbstractGraphicsDevice;
 import javax.media.nativewindow.NativeSurface;
-import javax.media.nativewindow.SurfaceUpdatedListener;
 import javax.media.nativewindow.WindowClosingProtocol;
 import javax.media.opengl.GL;
 import javax.media.opengl.GL2;
@@ -355,7 +354,6 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
     this.chooser = chooser;
 
     helper = new GLDrawableHelper();
-    helper.setAutoSwapBufferMode(false); /** Always handles buffer swapping in Backend! */
     if( null != shareWith ) {
         helper.setSharedContext(null, shareWith);
     }
@@ -945,18 +943,13 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
   }
 
   @Override
-  public void setAutoSwapBufferMode(boolean onOrOff) {
-    // In the current implementation this is a no-op.
-    // All Backend's require control of buffer swapping,
-    // i.e. as required for MSAA offscreen FBO buffer.
+  public void setAutoSwapBufferMode(boolean enable) {
+    helper.setAutoSwapBufferMode(enable);
   }
 
   @Override
   public boolean getAutoSwapBufferMode() {
-    // In the current implementation this is a no-op.
-    // All Backend's require control of buffer swapping,
-    // i.e. as required for MSAA offscreen FBO buffer.
-    return true;
+    return helper.getAutoSwapBufferMode();
   }
 
   @Override
@@ -1402,8 +1395,6 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
     private volatile GLContextImpl offscreenContext; // volatile: avoid locking for read-only access
     private boolean flipVertical;
 
-    private boolean needsSwapBuffers = true;
-
     // For saving/restoring of OpenGL state during ReadPixels
     private final GLPixelStorageModes psm =  new GLPixelStorageModes();
 
@@ -1439,12 +1430,6 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
                                                     chooser,
                                                     panelWidth, panelHeight);
           offscreenDrawable.setRealized(true);
-          offscreenDrawable.getNativeSurface().addSurfaceUpdatedListener(new SurfaceUpdatedListener() {
-              @Override
-              public final void surfaceUpdated(Object updater, NativeSurface ns, long when) {
-                  needsSwapBuffers = false;
-              } } );
-
           offscreenContext = (GLContextImpl) offscreenDrawable.createContext(shareWith[0]);
           offscreenContext.setContextCreationFlags(additionalCtxCreationFlags);
           if( GLContext.CONTEXT_NOT_CURRENT < offscreenContext.makeCurrent() ) {
@@ -1564,7 +1549,7 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
 
     @Override
     public final boolean preGL(Graphics g) {
-      needsSwapBuffers = true;
+      // Empty in this implementation
       return true;
     }
 
@@ -1579,6 +1564,9 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
     @Override
     public final void postGL(Graphics g, boolean isDisplay) {
       if (isDisplay) {
+        // offscreenDrawable is already swapped,
+        // either by GLDrawableHelper.invoke or user's GLEL according to auto-swap-buffer-mode.
+
         final GL gl = offscreenContext.getGL();
 
         final int componentCount;
@@ -1666,10 +1654,6 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
             gl2es3.glReadBuffer(gl2es3.getDefaultReadBuffer());
         }
 
-        if( needsSwapBuffers ) {
-            offscreenDrawable.swapBuffers();
-        }
-
         if(null != glslTextureRaster) { // implies flippedVertical
             final boolean viewportChange;
             final int[] usrViewport = new int[] { 0, 0, 0, 0 };