RFR: 8264999: GeneralPath.lineTo() to itself produces jagged lines [v2]

[Jeremy]

On Thu, 9 Jun 2022 02:16:45 GMT, Jeremy <duke at openjdk.java.net> wrote:

>> Previously when you drew a line that moved exactly (+0, +0) with a miter stroke the Stroker class acted like a horizontal miter was appropriate. Now we abort instead, so no miter is applied.
>> 
>> The new unit test tests the original steps plus several variations.
>> 
>> I'm a little nervous about this change because it looks like someone previously considered this exact condition and implemented a different behavior. I don't think I understand the original rationale.
>
> Jeremy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   JDK-8264999: GeneralPath.lineTo() to itself produces jagged lines
>   
>   Adding "&& prev == DRAWING_OP_TO" per Laurent's code review.
>   
>   I also redid the unit tests. Before this change, with the new unit tests: one scenario failed. With this change: four scenarios failed.
>   
>   For now I've commented out the failing tests. The failing tests are not the same as the original bug; they are related considerations we should also test against, but IMO they are not essential for the resolution of jdk-8264999.

Sorry I must have missed that code review.

I just pushed an update with your proposal.

On further review: I was dissatisfied with the unit tests, so I rewrote them. Some fail now. (Both before and after this commit.)

I commented out the failing test scenarios in this commit. They are not strictly required to resolve this ticket, so I'm not sure what our protocol is. (We could try to resolve these unit tests now so everything passes? Or we could submit a separate ticket for the remaining scenarios? Or something else?)

I'm open to suggestions regarding next steps.

-------------

PR: https://git.openjdk.java.net/jdk/pull/8943