RFR: 8358820: Allow interpolation outside of range [0,1] [v3]
Michael Strauß
mstrauss at openjdk.org
Sun Jul 27 18:48:18 UTC 2025
> JavaFX unnecessarily restricts interpolation in the following ways:
> 1. `Interpolatable` implementations often clamp intermediate values to the interpolation factor range [0,1].
> 2. `SplineInterpolator` doesn't accept Y coordinates outside of [0,1] for its control points. While this was probably done so that the computed interpolation factor doesn't exceed [0,1], the restriction goes far beyond that. For example, the following function is not representable, even though its values are all within the [0,1] range:<br>
> <img src="https://github.com/user-attachments/assets/368b6142-052d-4ead-8a59-cbddf4a19660" width="400"/><br>
> The following function is also not representable, but would be very useful for [bouncy animations](https://easings.net/#easeOutBack):<br>
> <img src="https://github.com/user-attachments/assets/af02b044-ae4c-4250-b181-72178ad9f3f3" width="400"/>
>
> Fortunately, there is no technical reason why JavaFX can't support the full range of animations that can be represented with a cubic Beziér interpolation function.
>
> This PR includes the following changes:
> 1. The specification of `Interpolatable` is changed to require implementations to accept interpolation factors outside of [0,1].
> 2. All implementations of `Interpolatable` now correctly return intermediate values outside of [0,1].
> 3. `SplineInterpolator` now accepts control points with any Y coordinate.
>
> Here's how the result looks like for the previously unrepresentable interpolation function `cubic-bezier(0.34, 2.2, 0.64, 1)`:<br>
> <img src="https://github.com/user-attachments/assets/72c10d0d-71b4-4bb5-b58c-ae377279b0fd" width="500"/>
Michael Strauß 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:
- Merge branch 'master' into feature/relaxed-interpolation
- javadoc
- Allow interpolation outside of range [0,1]
-------------
Changes:
- all: https://git.openjdk.org/jfx/pull/1822/files
- new: https://git.openjdk.org/jfx/pull/1822/files/92d06d7e..26208229
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jfx&pr=1822&range=02
- incr: https://webrevs.openjdk.org/?repo=jfx&pr=1822&range=01-02
Stats: 18401 lines in 224 files changed: 15325 ins; 2250 del; 826 mod
Patch: https://git.openjdk.org/jfx/pull/1822.diff
Fetch: git fetch https://git.openjdk.org/jfx.git pull/1822/head:pull/1822
PR: https://git.openjdk.org/jfx/pull/1822
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