How about option 3 -
NPE before imageComplete sends an ERROR as it does now.
NPE during imageComplete is ignored, both for backwards compatibility
and because it is more of a "hint" than an operation that requires
action from the consumer.
...jim
On 5/25/2016 1:31 AM, Ajit Ghaisas wrote:
Hi
Bug :
https://bugs.openjdk.java.net/browse/JDK-8139192
Custom ImageFilters return blank images in Java 8(.45) while working in 7
Root cause :
private method produce() in OffScreenImageSource.java consumes a
NullPointerException that originates from a custom ImageConsumer (a 3^rd
party image library class - com.jhlabs.image.WaterFilter)
Analysis:
1. How the behavior changed between JDK7 and JK8 :
A call to imageComplete(ImageConsumer.SINGLEFRAMEDONE) was added in
addition to imageComplete(ImageConsumer. STATICIMAGEDONE) as a fix for
JDK-7143612.
2. What debugging revealed:
A NullPointerException is being thrown from the library during the call
to imageComplete(ImageConsumer.STATICIMAGEDONE)
3. It looks like the fix of JDK-7143612 is valid and successive calls to
imageComplete() are allowed.
4. The 3rd party library behavior appears incorrect (if it can not
handle subsequent calls to imageComplete(), it should de-register itself).
The 3rd-party library code should be fixed.
Possible modifications in JDK :
Currently, OffScreenImageSource::produce() consumes the
NullPointerException - this is incorrect and results in silent failure
of this particular image filter.
We need to let the image filter library know that exception has occurred
in its code and not in JDK. We have two options -
Option 1 : Rethrow the NullPointerException --- It is the clearest way
to let 3^rd party library know that their code is erroneous with latest
JDK. This will change the 3^rd party image filter behavior that
generates blank image.
Option 2 : Add a stack trace where the exception is being consumed ---
Adding stack trace provides more information regarding failure of 3^rd
party image filter with retaining the current behavior that generates
blank image.
I have implemented both the options:
Option 1: http://cr.openjdk.java.net/~aghaisas/8139192/webrev.00/
Option 2: http://cr.openjdk.java.net/~aghaisas/8139192/webrev.01/
Request you to review both the webrevs and provide your preference.
I will add a test to the selected webrev.
Regards,
Ajit
