On Thu, 27 Apr 2023 19:04:39 GMT, John Hendrikx <[email protected]> wrote:
>> Region has floor and ceiling functions that ensure that calling them twice >> in a row will yield the same result: >> >> ceil(x) = ceil(ceil(x)) >> >> However, due to use of a constant `EPSILON` which is added/subtracted before >> doing the rounding, this only works for small numbers (in the range of 0-50 >> approximately). For larger values and scales, rounding errors can easily >> occur. This is visible as artifacts on screen where controls are a pixel >> wider than they should be. >> >> The use of the `EPSILON` constant is incorrect, as its value depends on the >> magnitude of the value in question (as magnitude increases, the fractional >> precision decreases). >> >> The Math class offers the function `ulp` that should be used here. It >> represents the smallest possible change in value for a given double. >> >> Extending the existing test case >> `snappingASnappedValueGivesTheSameValueTest` to use larger magnitude numbers >> exposes the problems. > > John Hendrikx has updated the pull request with a new target base due to a > merge or a rebase. The incremental webrev excludes the unrelated changes > brought in by the merge/rebase. The pull request contains three additional > commits since the last revision: > > - Print seed if test fails > - Merge branch 'master' into feature/ceil-fix > - Fix Region ceil/floor function guarantees to be more accurate modules/javafx.graphics/src/test/java/test/javafx/scene/layout/RegionTest.java line 1281: > 1279: } > 1280: > 1281: random.setSeed(seed); it might be better to set the seed only once at the beginning. otherwise the next 2 tests use the same sequence of doubles due to the seed being the same. or is this intentional? ------------- PR Review Comment: https://git.openjdk.org/jfx/pull/1118#discussion_r1179576437
