On Thu, 27 Apr 2023 10:11:42 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. This pull request has now been integrated. Changeset: 7825137d Author: John Hendrikx <[email protected]> URL: https://git.openjdk.org/jfx/commit/7825137dc2d9f8d4ebc50c864522fae990cadc71 Stats: 418 lines in 7 files changed: 339 ins; 44 del; 35 mod 8306990: The guarantees given by Region's floor and ceiling functions should work for larger values Reviewed-by: angorya, mstrauss ------------- PR: https://git.openjdk.org/jfx/pull/1118
