Remove the Gradient type and its module

[Ogeon]

As discussed in #218, the Gradient type has not gotten the attention it deserves and it's better to remove it in favor of other alternatives. This will also make the library more focused and easier to maintain. The predefined, named gradient constants are also removed.

Closed Issues

• Closes B-spline interpolation #152, since the Gradient is now gone.
• Closes Redesign and improve the Gradient type and friends #156, since the Gradient is now gone.

Breaking Change

Both Gradient and gradient::named are gone with no replacement, in favor of better alternatives in other crates.

[Ogeon]

I'm thinking of making it possible to multiply hues as if they are just regular numbers but will probably do that separately. That should make it possible to skip having an interpolation adapter for those types.

[github-actions]

Benchmark for aab81e1

Click to view benchmark

Test	Base	PR	%
Cie family/lab to lch	4.1±0.16µs	4.1±0.13µs	0.00%
Cie family/lab to xyz	1055.4±64.45ns	1051.7±41.48ns	-0.35%
Cie family/lch to lab	2.7±0.15µs	2.7±0.11µs	0.00%
Cie family/linsrgb to xyz	5.2±0.15µs	5.5±0.33µs	+5.77%
Cie family/linsrgb to xyz - wide::f32x8	1133.0±37.58ns	1032.9±23.60ns	-8.83%
Cie family/xyz to lab	22.2±1.41µs	21.8±0.94µs	-1.80%
Cie family/xyz to yxy	770.4±119.55ns	745.1±22.35ns	-3.28%
Cie family/yxy to xyz	747.4±43.13ns	743.0±30.51ns	-0.59%
Matrix functions/matrix_inverse	14.4±1.57ns	13.6±0.42ns	-5.56%
Matrix functions/multiply_3x3	10.5±0.50ns	10.8±0.62ns	+2.86%
Matrix functions/multiply_rgb_to_xyz	5.8±0.25ns	6.1±0.35ns	+5.17%
Matrix functions/multiply_xyz	6.0±0.76ns	5.9±0.18ns	-1.67%
Matrix functions/multiply_xyz_to_rgb	5.8±0.32ns	5.9±0.20ns	+1.72%
Matrix functions/rgb_to_xyz_matrix	29.3±0.94ns	29.6±1.91ns	+1.02%
Rgb family/hsl to hsv	902.5±41.55ns	890.6±33.02ns	-1.32%
Rgb family/hsl to linear hsl	16.9±0.72µs	16.7±0.98µs	-1.18%
Rgb family/hsl to rgb	2.7±0.16µs	2.7±0.19µs	0.00%
Rgb family/hsv to hsl	1108.3±66.82ns	1060.2±55.22ns	-4.34%
Rgb family/hsv to hwb	233.2±23.45ns	235.8±16.85ns	+1.11%
Rgb family/hsv to linear hsv	15.8±0.62µs	15.9±0.75µs	+0.63%
Rgb family/hsv to rgb	2.4±0.08µs	2.4±0.11µs	0.00%
Rgb family/hwb to hsv	596.6±29.98ns	596.9±27.23ns	+0.05%
Rgb family/hwb to linear hwb	16.9±0.88µs	16.7±0.46µs	-1.18%
Rgb family/linear hsl to hsl	14.0±0.55µs	13.9±0.50µs	-0.71%
Rgb family/linear hsv to hsv	13.0±0.51µs	13.0±0.46µs	0.00%
Rgb family/linear hwb to hwb	14.0±0.49µs	14.3±0.69µs	+2.14%
Rgb family/linsrgb to rgb	7.4±0.35µs	7.6±0.55µs	+2.70%
Rgb family/linsrgb to rgb - wide::f32x8	8.0±0.19µs	8.5±0.27µs	+6.25%
Rgb family/linsrgb_f32 to rgb_u8	1072.5±35.45ns	1081.9±81.79ns	+0.88%
Rgb family/linsrgb_f64 to rgb_u8	1412.9±51.97ns	1424.3±60.08ns	+0.81%
Rgb family/rgb to hsl	1050.7±34.93ns	1058.4±47.92ns	+0.73%
Rgb family/rgb to hsl - wide::f32x8	663.8±29.65ns	666.9±30.86ns	+0.47%
Rgb family/rgb to hsv	766.9±40.21ns	763.1±22.45ns	-0.50%
Rgb family/rgb to hsv - wide::f32x8	642.7±31.81ns	639.8±29.17ns	-0.45%
Rgb family/rgb to linsrgb	10.6±0.49µs	10.4±0.37µs	-1.89%
Rgb family/rgb to linsrgb - wide::f32x8	6.0±0.25µs	6.2±0.33µs	+3.33%
Rgb family/rgb_u8 to linsrgb_f32	342.4±15.51ns	350.9±21.61ns	+2.48%
Rgb family/rgb_u8 to linsrgb_f64	346.2±12.90ns	345.3±11.49ns	-0.26%
Rgb family/xyz to linsrgb	8.6±0.27µs	9.1±0.52µs	+5.81%
Rgb family/xyz to linsrgb - wide::f32x8	1330.6±70.35ns	1396.6±263.11ns	+4.96%

[Ogeon]

bors r+

[bors]

Build succeeded:

• ci

[github-actions]

Benchmark for 19623cf

Click to view benchmark

Test	Base	PR	%
Cie family/lab to lch	3.1±0.01µs	3.1±0.02µs	0.00%
Cie family/lab to xyz	762.2±3.44ns	773.6±54.45ns	+1.50%
Cie family/lch to lab	2.4±0.01µs	2.4±0.01µs	0.00%
Cie family/linsrgb to xyz	4.4±0.03µs	4.3±0.02µs	-2.27%
Cie family/linsrgb to xyz - wide::f32x8	780.6±12.02ns	762.0±19.05ns	-2.38%
Cie family/xyz to lab	21.1±0.10µs	21.2±0.31µs	+0.47%
Cie family/xyz to yxy	657.6±5.44ns	662.8±12.14ns	+0.79%
Cie family/yxy to xyz	527.4±1.97ns	529.5±5.56ns	+0.40%
Matrix functions/matrix_inverse	11.5±0.04ns	11.5±0.06ns	0.00%
Matrix functions/multiply_3x3	10.5±0.07ns	10.6±0.43ns	+0.95%
Matrix functions/multiply_rgb_to_xyz	6.4±0.03ns	6.7±0.43ns	+4.69%
Matrix functions/multiply_xyz	6.4±0.04ns	6.5±0.21ns	+1.56%
Matrix functions/multiply_xyz_to_rgb	6.4±0.02ns	6.6±0.32ns	+3.13%
Matrix functions/rgb_to_xyz_matrix	30.1±0.09ns	30.1±0.16ns	0.00%
Rgb family/hsl to hsv	643.9±6.70ns	644.3±3.69ns	+0.06%
Rgb family/hsl to linear hsl	12.7±0.05µs	12.8±0.08µs	+0.79%
Rgb family/hsl to rgb	1983.3±7.67ns	1982.3±7.74ns	-0.05%
Rgb family/hsv to hsl	826.4±8.94ns	845.6±11.53ns	+2.32%
Rgb family/hsv to hwb	223.0±0.85ns	229.5±0.93ns	+2.91%
Rgb family/hsv to linear hsv	12.2±0.08µs	12.6±0.12µs	+3.28%
Rgb family/hsv to rgb	1865.4±12.93ns	1861.0±136.43ns	-0.24%
Rgb family/hwb to hsv	464.9±3.78ns	465.3±5.52ns	+0.09%
Rgb family/hwb to linear hwb	12.7±0.05µs	13.2±0.13µs	+3.94%
Rgb family/linear hsl to hsl	10.7±0.03µs	10.7±0.12µs	0.00%
Rgb family/linear hsv to hsv	10.1±0.04µs	10.1±0.05µs	0.00%
Rgb family/linear hwb to hwb	10.8±0.05µs	10.8±0.05µs	0.00%
Rgb family/linsrgb to rgb	5.5±0.02µs	5.5±0.02µs	0.00%
Rgb family/linsrgb to rgb - wide::f32x8	7.4±0.03µs	7.4±0.03µs	0.00%
Rgb family/linsrgb_f32 to rgb_u8	908.5±4.55ns	906.7±3.06ns	-0.20%
Rgb family/linsrgb_f64 to rgb_u8	1169.1±9.12ns	1167.3±5.31ns	-0.15%
Rgb family/rgb to hsl	793.4±3.35ns	799.9±3.60ns	+0.82%
Rgb family/rgb to hsl - wide::f32x8	501.4±10.48ns	494.8±4.21ns	-1.32%
Rgb family/rgb to hsv	498.1±1.88ns	500.8±1.78ns	+0.54%
Rgb family/rgb to hsv - wide::f32x8	443.2±1.66ns	443.4±7.96ns	+0.05%
Rgb family/rgb to linsrgb	7.4±0.03µs	7.5±0.06µs	+1.35%
Rgb family/rgb to linsrgb - wide::f32x8	5.6±0.02µs	5.6±0.03µs	0.00%
Rgb family/rgb_u8 to linsrgb_f32	327.9±1.03ns	327.8±1.09ns	-0.03%
Rgb family/rgb_u8 to linsrgb_f64	331.3±1.26ns	328.4±1.80ns	-0.88%
Rgb family/xyz to linsrgb	8.0±0.05µs	7.9±0.02µs	-1.25%
Rgb family/xyz to linsrgb - wide::f32x8	1239.5±6.89ns	1238.0±6.02ns	-0.12%

[medzernik]

Are there any alternatives in other libraries that could replace the lost functionality? I would appreciate a tip.

[Ogeon]

I would recommend enterpolation if you want something similar to the old gradient module. Other interpolation crates should work as well, but this one is the closest to a spiritual successor.