RFR: 8326027: Comparing buffered images of white background frame fails in Mac

[Alexey Ivanov]

On Mon, 2 Sep 2024 05:03:25 GMT, Jayathirth D V <jdv at openjdk.org> wrote:

>>> Why are we extending this test to be run on Mac now? Looks like it was Linux specific test.
>>> 
>>> Also Title "Comparing buffered images of white background frame fails in Mac" makes it looks like some product issue. But changes are related to a single test, if we are making single test related changes its better to have [Testbug] or test in the title instead of issue description.
>>> 
>>> This color comparison failure is happening when we are checking boundary pixels of a window or is it happening everywhere?
>> 
>> 1. The product fix was linux specific, yet I guess there were review suggestions  on extending the test to other  OS. Hence while testing on other platforms few issues w.r.t OS for this test was observed and JBS was raised (For Windows - [JDK-8326026](https://bugs.openjdk.org/browse/JDK-8326026) - Mouse drag for a transparent frame fails in Windows) 
>> 2. Will update the title.
>> 3. Its not happening at borders, its at random places, u can refer to the image attached in JBS.
>
>> > Why are we extending this test to be run on Mac now? Looks like it was Linux specific test.
>> > Also Title "Comparing buffered images of white background frame fails in Mac" makes it looks like some product issue. But changes are related to a single test, if we are making single test related changes its better to have [Testbug] or test in the title instead of issue description.
>> > This color comparison failure is happening when we are checking boundary pixels of a window or is it happening everywhere?
>> 
>>     1. The product fix was linux specific, yet I guess there were review suggestions  on extending the test to other  OS. Hence while testing on other platforms few issues w.r.t OS for this test was observed and JBS was raised (For Windows - [JDK-8326026](https://bugs.openjdk.org/browse/JDK-8326026) - Mouse drag for a transparent frame fails in Windows)
>> 
>>     2. Will update the title.
>> 
>>     3. Its not happening at borders, its at random places, u can refer to the image attached in JBS.
> 
> Please share product fix for which the original test update was done.

@jayathirthrao  It looks as if image comparison is a common issue on macOS, tolerance is usually added for macOS.

Sometimes colour difference is because of a color profile used; that's why the guidelines recommend setting the same common profile on all the test systems.

I suspect the other reason is because of High DPI (Retina) displays on Macs. Yet it has never been confirmed or disconfirmed.

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PR Comment: https://git.openjdk.org/jdk/pull/20760#issuecomment-2324545326