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Add lerp_rect_unpremultiplied #199

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Add `lerp_rect_unpremultiplied`
sagudev Oct 6, 2025
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sagudev Oct 6, 2025
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5 changes: 5 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -15,6 +15,10 @@ You can find its changes [documented below](#032-2025-09-10).

This release has an [MSRV][] of 1.82.

### Added

* Add `lerp_rect_unpremultiplied` to interpolate `AlphaColor` without premultiplying alpha (in unpremultiplied "straight" alpha space). ([#199][] by [@tomcur][])

## [0.3.2][] (2025-09-10)

This release has an [MSRV][] of 1.82.
Expand Down Expand Up @@ -209,6 +213,7 @@ This is the initial release.
[#175]: https://github.com/linebender/color/pull/175
[#185]: https://github.com/linebender/color/pull/185
[#190]: https://github.com/linebender/color/pull/190
[#199]: https://github.com/linebender/color/pull/199

[Unreleased]: https://github.com/linebender/color/compare/v0.3.2...HEAD
[0.3.2]: https://github.com/linebender/color/releases/tag/v0.3.2
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10 changes: 10 additions & 0 deletions color/src/color.rs
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Expand Up @@ -475,6 +475,16 @@ impl<CS: ColorSpace> AlphaColor<CS> {
.un_premultiply()
}

/// Interpolate colors without premultiplying alpha (in unpremultiplied "straight" alpha space).
///
/// Note: this function doesn't fix up hue in cylindrical spaces. It is
/// still useful if the hue angles are compatible, particularly if the
/// fixup has been applied.
#[must_use]
pub fn lerp_rect_unpremultiplied(self, other: Self, t: f32) -> Self {
self + t * (other - self)
}

/// Linearly interpolate colors, with hue fixup if needed.
#[must_use]
pub fn lerp(self, other: Self, t: f32, direction: HueDirection) -> Self {
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