[OpenJDK 2D-Dev] [9] Fix for JDK-8160421 : Regression: JDK-8139192 causes NPE in java.awt.Toolkit.createCustomCursor()

[Ajit Ghaisas]

Hi,

Bug :
    This is regarding a NPE getting printed as stacktrace in java.awt.Toolkit.createCustomCursor() method.
    The bug is described at : https://bugs.openjdk.java.net/browse/JDK-8160421

Root Cause :
    Fix of bug JDK-8139192 : Custom ImageFilters return blank images in Java 8(.45) while working in 7. 
    The above fix added a RuntimeException catch & log mechanism to support a ImageFilter which was broken due to the second imageComplete() call in OffScreenImageSource.produce() method.
   
Analysis:
    Without the fix of JDK-8139192, java.awt.Toolkit.createCustomCursor() call results in 
    NullPointerException when imageComplete(ImageConsumer.STATICIMAGEDONE) call is made - but, it gets consumed silently.
    Cathing RuntimeException() out of imageComplete(ImageConsumer.STATICIMAGEDONE) was added to fix JDK-8160421.
    This started catching & logging the exception in case 'theConsumer' has unregistered itself as a result of call            
                   theConsumer.imageComplete(ImageConsumer.SINGLEFRAMEDONE);
     This log is undesirable as this mechanism is used in java.awt.Toolkit.createCustomCursor() and may be in other places.

Fix :
    Make the call to imageComplete(ImageConsumer.STATICIMAGEDONE) only if 'theConsumer' has not been unregistered.

Webrev:
    http://cr.openjdk.java.net/~aghaisas/8160421/webrev.00/

Request you to review.

Regards,
Ajit