Split and rework the `Blend` trait and bump MSRV to 1.55.0

[Ogeon]

The Blend trait has been split into Compose, Blend and BlendWith, to allow more color spaces to be composed. The trait implementations were also changed from a default implementation to blanket implementations. Having blanket implementations allows users to only require the trait to be implemented without having to specify the trait's requirements. For example, it's only required to specify where C: Blend instead of listing all the mathematical requirements.

The PreAlpha type has also been changed a lot to get rid of the alpha type parameter and to leave premultiplication to the color types. A lot of it was developed in tandem with changing how the blending was implemented to make those implementations make more sense.

Closed Issues

• Closes #243.

Breaking Change

The Blend trait, the PreAlpha type and a lot of associated API has been changed. Most users should not notice too much, except for needing a different trait or getting it from the blend module. The ComponentWise trait is also gone, since all colors can be cast to arrays for iteration

MSRV is changed to 1.55.0 to be able to use [T; N]::map.

[Ogeon]

This is what I have been up to for the past few weeks. At least to and from. There is still room for improvement but it should at least be more useful and less confusing than before. And the examples helps with verifying the implementation. Note, when looking at them, that they use linear colors. Many applications will not do that, so they may differ a bit. I'm considering allowing any RGB encoding for that reason.

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Benchmark for 017b4d7

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| Test | Base | PR | % | |------|--------------|------------------|---| | Cie family/lab to lch | 3.0±0.15µs | 3.0±0.22µs | 0.00% | | Cie family/lab to xyz | 800.4±46.74ns | 796.5±38.49ns | -0.49% | | Cie family/lch to lab | 2.3±0.10µs | 2.2±0.11µs | -4.35% | | Cie family/linsrgb to xyz | 3.3±0.07µs | 3.3±0.16µs | 0.00% | | Cie family/xyz to lab | 18.1±1.01µs | 17.3±0.97µs | -4.42% | | Cie family/xyz to yxy | 662.3±27.83ns | 669.0±19.98ns | +1.01% | | Cie family/yxy to xyz | 507.5±25.95ns | 491.9±31.01ns | -3.07% | | Matrix functions/matrix_inverse | 10.0±0.54ns | **9.4±0.31ns** | **-6.00%** | | Matrix functions/multiply_3x3 | 13.8±0.72ns | 13.7±0.81ns | -0.72% | | Matrix functions/multiply_rgb_to_xyz | 6.4±0.26ns | 6.3±0.34ns | -1.56% | | Matrix functions/multiply_xyz | 6.3±0.40ns | 6.2±0.32ns | -1.59% | | Matrix functions/multiply_xyz_to_rgb | 6.3±0.31ns | 6.2±0.34ns | -1.59% | | Matrix functions/rgb_to_xyz_matrix | 21.6±1.16ns | **20.4±1.16ns** | **-5.56%** | | Rgb family/hsl to hsv | 637.1±8.59ns | **564.3±14.98ns** | **-11.43%** | | Rgb family/hsl to linear hsl | **9.9±0.57µs** | 10.6±0.18µs | **+7.07%** | | Rgb family/hsl to rgb | 2.2±0.11µs | 2.1±0.18µs | -4.55% | | Rgb family/hsv to hsl | 913.4±54.56ns | **861.5±18.40ns** | **-5.68%** | | Rgb family/hsv to hwb | 223.2±12.03ns | **208.2±7.41ns** | **-6.72%** | | Rgb family/hsv to linear hsv | **9.5±1.57µs** | 9.9±0.15µs | **+4.21%** | | Rgb family/hsv to rgb | **2.1±0.13µs** | 2.2±0.07µs | **+4.76%** | | Rgb family/hwb to hsv | 621.6±16.89ns | **561.1±22.96ns** | **-9.73%** | | Rgb family/hwb to linear hwb | 10.7±0.63µs | 10.2±0.55µs | -4.67% | | Rgb family/linear hsl to hsl | 10.6±0.41µs | **9.9±0.57µs** | **-6.60%** | | Rgb family/linear hsv to hsv | 9.6±0.51µs | 9.8±0.55µs | +2.08% | | Rgb family/linear hwb to hwb | 11.1±0.51µs | **10.4±0.63µs** | **-6.31%** | | Rgb family/linsrgb to rgb | 5.8±0.33µs | 6.0±0.36µs | +3.45% | | Rgb family/linsrgb_f32 to rgb_u8 | **6.4±0.36µs** | 6.9±0.09µs | **+7.81%** | | Rgb family/rgb to hsl | 818.4±42.63ns | **762.7±31.88ns** | **-6.81%** | | Rgb family/rgb to hsv | 677.0±17.32ns | **654.3±37.36ns** | **-3.35%** | | Rgb family/rgb to linsrgb | 5.6±0.31µs | 5.5±0.30µs | -1.79% | | Rgb family/rgb_u8 to linsrgb_f32 | **6.1±0.34µs** | 6.4±0.15µs | **+4.92%** | | Rgb family/xyz to linsrgb | 5.4±0.29µs | 5.6±0.20µs | +3.70% |

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Benchmark for 656865a

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| Test | Base | PR | % | |------|--------------|------------------|---| | Cie family/lab to lch | 4.0±0.18µs | 4.0±0.25µs | 0.00% | | Cie family/lab to xyz | 1008.0±32.54ns | 1010.0±46.70ns | +0.20% | | Cie family/lch to lab | 2.9±0.13µs | 2.9±0.11µs | 0.00% | | Cie family/linsrgb to xyz | 4.4±0.18µs | 4.4±0.16µs | 0.00% | | Cie family/xyz to lab | 22.5±1.23µs | 22.4±0.75µs | -0.44% | | Cie family/xyz to yxy | 813.9±28.18ns | 825.0±38.47ns | +1.36% | | Cie family/yxy to xyz | 643.3±22.95ns | 649.0±29.66ns | +0.89% | | Matrix functions/matrix_inverse | 13.0±0.77ns | 12.6±0.49ns | -3.08% | | Matrix functions/multiply_3x3 | 17.5±0.68ns | 17.4±0.78ns | -0.57% | | Matrix functions/multiply_rgb_to_xyz | 8.1±0.51ns | 8.0±0.27ns | -1.23% | | Matrix functions/multiply_xyz | 8.1±0.43ns | 8.0±0.25ns | -1.23% | | Matrix functions/multiply_xyz_to_rgb | 8.1±0.41ns | 8.0±0.27ns | -1.23% | | Matrix functions/rgb_to_xyz_matrix | 27.4±1.27ns | 27.0±0.88ns | -1.46% | | Rgb family/hsl to hsv | 782.0±53.23ns | 767.4±21.38ns | -1.87% | | Rgb family/hsl to linear hsl | 12.8±0.53µs | 12.9±0.66µs | +0.78% | | Rgb family/hsl to rgb | 2.8±0.17µs | 2.8±0.13µs | 0.00% | | Rgb family/hsv to hsl | 1175.1±49.37ns | 1187.0±54.04ns | +1.01% | | Rgb family/hsv to hwb | 281.2±9.68ns | 280.6±8.63ns | -0.21% | | Rgb family/hsv to linear hsv | 12.5±0.70µs | 12.1±0.44µs | -3.20% | | Rgb family/hsv to rgb | 2.7±0.12µs | 2.7±0.09µs | 0.00% | | Rgb family/hwb to hsv | 766.6±46.66ns | 759.0±25.24ns | -0.99% | | Rgb family/hwb to linear hwb | 13.8±0.52µs | 13.7±0.88µs | -0.72% | | Rgb family/linear hsl to hsl | 13.3±0.42µs | 12.9±0.52µs | -3.01% | | Rgb family/linear hsv to hsv | 12.7±0.50µs | 12.4±0.71µs | -2.36% | | Rgb family/linear hwb to hwb | 14.0±0.66µs | 13.9±0.41µs | -0.71% | | Rgb family/linsrgb to rgb | 7.5±0.32µs | 7.4±0.21µs | -1.33% | | Rgb family/linsrgb_f32 to rgb_u8 | 8.4±0.25µs | 8.4±0.34µs | 0.00% | | Rgb family/rgb to hsl | 1040.3±55.57ns | 1036.5±40.14ns | -0.37% | | Rgb family/rgb to hsv | 816.5±24.03ns | 823.7±45.41ns | +0.88% | | Rgb family/rgb to linsrgb | 7.2±0.29µs | 7.1±0.23µs | -1.39% | | Rgb family/rgb_u8 to linsrgb_f32 | 7.8±0.54µs | 7.8±0.45µs | 0.00% | | Rgb family/xyz to linsrgb | 6.8±0.25µs | 6.9±0.64µs | +1.47% |

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Benchmark for 05ac1dc

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| Test | Base | PR | % | |------|--------------|------------------|---| | Cie family/lab to lch | 3.3±0.05µs | 3.3±0.04µs | 0.00% | | Cie family/lab to xyz | 825.9±9.96ns | 825.8±13.16ns | -0.01% | | Cie family/lch to lab | **2.3±0.03µs** | 2.4±0.04µs | **+4.35%** | | Cie family/linsrgb to xyz | 3.7±0.09µs | 3.7±0.06µs | 0.00% | | Cie family/xyz to lab | 18.5±0.34µs | 18.6±0.81µs | +0.54% | | Cie family/xyz to yxy | 671.1±9.98ns | 672.3±10.39ns | +0.18% | | Cie family/yxy to xyz | 533.1±11.29ns | 533.2±9.82ns | +0.02% | | Matrix functions/matrix_inverse | 10.9±0.19ns | **10.6±0.16ns** | **-2.75%** | | Matrix functions/multiply_3x3 | 14.5±0.18ns | 14.5±0.26ns | 0.00% | | Matrix functions/multiply_rgb_to_xyz | 6.6±0.11ns | 6.6±0.09ns | 0.00% | | Matrix functions/multiply_xyz | 6.6±0.20ns | 6.6±0.09ns | 0.00% | | Matrix functions/multiply_xyz_to_rgb | 6.6±0.10ns | 6.6±0.13ns | 0.00% | | Matrix functions/rgb_to_xyz_matrix | 22.5±0.29ns | 22.5±0.32ns | 0.00% | | Rgb family/hsl to hsv | 639.7±14.07ns | 636.6±11.35ns | -0.48% | | Rgb family/hsl to linear hsl | 10.5±0.17µs | 10.5±0.23µs | 0.00% | | Rgb family/hsl to rgb | 2.3±0.05µs | 2.3±0.03µs | 0.00% | | Rgb family/hsv to hsl | 981.8±21.49ns | 971.3±11.38ns | -1.07% | | Rgb family/hsv to hwb | 231.9±3.17ns | 233.6±7.84ns | +0.73% | | Rgb family/hsv to linear hsv | 10.0±0.13µs | 10.0±0.22µs | 0.00% | | Rgb family/hsv to rgb | 2.2±0.04µs | 2.2±0.06µs | 0.00% | | Rgb family/hwb to hsv | 626.1±10.39ns | 625.3±10.36ns | -0.13% | | Rgb family/hwb to linear hwb | 11.2±0.13µs | 11.2±0.19µs | 0.00% | | Rgb family/linear hsl to hsl | 10.6±0.18µs | 10.6±0.17µs | 0.00% | | Rgb family/linear hsv to hsv | 10.2±0.17µs | 10.1±0.14µs | -0.98% | | Rgb family/linear hwb to hwb | 11.4±0.23µs | 11.4±0.19µs | 0.00% | | Rgb family/linsrgb to rgb | 6.2±0.16µs | 6.2±0.08µs | 0.00% | | Rgb family/linsrgb_f32 to rgb_u8 | 6.9±0.13µs | 6.8±0.11µs | -1.45% | | Rgb family/rgb to hsl | 848.0±13.02ns | 847.8±11.98ns | -0.02% | | Rgb family/rgb to hsv | 681.5±9.57ns | 688.4±15.37ns | +1.01% | | Rgb family/rgb to linsrgb | 6.0±0.07µs | **5.9±0.09µs** | **-1.67%** | | Rgb family/rgb_u8 to linsrgb_f32 | 6.4±0.11µs | 6.4±0.11µs | 0.00% | | Rgb family/xyz to linsrgb | **5.6±0.08µs** | 5.7±0.08µs | **+1.79%** |

[Ogeon]

bors r+

[bors[bot]]

Build succeeded:

• ci