On Fri, 5 May 2023 08:08:30 GMT, John Hendrikx <jhendr...@openjdk.org> 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 incrementally with three
> additional commits since the last revision:
>
> - Remove seed
> - Add test cases for negative values
> - Add copyright headers
LGTM
modules/javafx.graphics/src/main/java/com/sun/javafx/scene/layout/ScaledMath.java
line 31:
> 29: * Math functions which deal with rounding scaled values.
> 30: */
> 31: public class ScaledMath {
If you want, you could make this class final and give it a private constructor.
But since this is not public API, it probably doesn't matter all that much.
modules/javafx.graphics/src/test/java/test/javafx/scene/layout/RegionTest.java
line 1323:
> 1321:
> 1322: double[] scales = new double[] {1.0, 1.25, 1.5, 1.75, 2.0,
> 1.374562997, 20.0};
> 1323: Random random = new Random();
In my opinion, using a fixed seed would have been preferable here.
-------------
Marked as reviewed by mstrauss (Committer).
PR Review: https://git.openjdk.org/jfx/pull/1118#pullrequestreview-1454069449
PR Review Comment: https://git.openjdk.org/jfx/pull/1118#discussion_r1212251622
PR Review Comment: https://git.openjdk.org/jfx/pull/1118#discussion_r1212250917
