RFR: 8199592: Control labels truncated at certain DPI scaling levels

[Jeanette Winzenburg]

On Sat, 24 Oct 2020 18:50:22 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> As discussed in the [JBS issue](https://bugs.openjdk.java.net/browse/JDK-8199592), when snapping an already snapped value (either intentionally or by  mistake), the result should be the same, otherwise we'll be jumping unnecessary from a valid pixel to another pixel.
>> 
>> This PR provides a fix to `snapSizeXX` methods used in `Region`, which ultimately use `Math.ceil`, by subtracting an epsilon value to scaled value before ceiling, to ensure snapping a snapped value gives the same value.
>> 
>> A test to verify `snapSizeX` and `snapSizeY` with 1000 random values, and 6 different UI scales is provided.
>> For the 1.0, 1.25, 1.5 and 2.0 UI scales, the current approach works fine. Only for 1.75 and the random 1.374562997 value fails (the test fails for around 2% of the values with 1.75 and around 10% with 1.374562997).
>> With the proposed fix, it doesn't fail at all.
>
> The approach looks good. I'll review it early next week, and also ask @arapte to review.

curious: it this expected to fix the ellipsed checkBox texts? Can verify that the test fails/passes before/after the fix, but the example in the report looks still is eclipsed: same for 1.5, slightly better (in that only the first text is eclipsed compared to the first 3 without) for 1.75 scaling. What am I missing?

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PR: https://git.openjdk.java.net/jfx/pull/336