[OpenJDK 2D-Dev] Fix for JDK-8139192 : Custom ImageFilters return blank images in Java 8(.45) while working in 7

[Sergey Bylokhov]

On 25.05.16 23:33, Jim Graham wrote:
> 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.

I guess the case is that when we ignore this NPE(w/o any notification) 
the users complains that the bug is in jdk.

>
>             ...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
>>
>>
>>
>>
>>
>>
>>
>>
>>


-- 
Best regards, Sergey.