On Fri, 23 Oct 2020 08:32:59 GMT, Jose Pereda <jper...@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. Looks good. I can confirm that this fixes the problem of `snapSizeXY(snapSizeXY(val)) != snapSizeXY(val)` and that it fixes the test case from [JDK-8199592](https://bugs.openjdk.java.net/browse/JDK-8199592) when `sizeToScene` is called (as noted above this is a fix for one of the two underlying problems). I also verified that the new test will catch the bug. ------------- Marked as reviewed by kcr (Lead). PR: https://git.openjdk.java.net/jfx/pull/336
