Dart port of HSLuv (revision 4) with a Flutter sample. This was a direct conversion of the reference implementation. The sample is available as a web app.
HSLuv is a human-friendly alternative to HSL.
It is like HSL, but color only gets perceptually lighter or darker when the Lightness attribute changes. In HSL, if you go from a green hue to a red one, there will be big differences in the perceived lightness. In HSLuv, almost none.
If you want to see for yourself, check the sample app and open the Color Compare screen. Contrast "only" changes when Lightness changes. When Hue or Saturation attributes change, there might be minimal changes in contrast (in the 0.01 range), but nothing perceivable and certainly better than HSV/HSL.
This is specially useful when building acessible color systems. For more information, check: Designing Color Spaces / Wikipedia article
In the pubspec.yaml
of your flutter project, add the following dependency:
dependencies:
hsluv: ^VERSION
In your project you can use it in two different ways, either low level (directly accessing values as a list<double>
) or high level (similar to HSLColor).
HSLuvColor
is easier to use, but has less flexibility than a raw list.
import 'package:hsluv/hsluv.dart';
void main() {
// Low level usage.
final List<double> hsluvLow = Hsluv.rgbToHsluv([0.2,0.5,0.7]);
print(Hsluv.hsluvToHex(hsluvLow));
// High level usage.
final hsluvFromColor = HSLuvColor.fromColor(Colors(0xffef3e4a));
print(hsluvFromColor.toString());
final hsluvFromHSL = HSLuvColor.fromHSL(300, 70, 60);
print(hsluvFromHSL.toString());
}
Sample app showing HSV (top) vs HSLuv (bottom). See how the perceived lightness changes as the hue slider moves.
- RGB values are ranging in [0...1]
- HSLuv and HPLuv values have different ranging for their components
- H : [0...360]
- S and L : [0...100]
- LUV has different ranging for their components
- L* : [0...100]
- u* and v* : [-100...100]
- LCh has different ranging for their components
- L* : [0...100]
- C* : [0...?] Upper bound varies depending on L* and H*
- H* : [0...360]
- XYZ values are ranging in [0...1]
Important: Flutter's HSLColor has lightness and saturation ranging from 0 to 1.0. HSLuv uses 0 to 100. There is a class, called HSInterColor in the sample that tries to mitigate this.
The passing/returning values, when not String
are List<double>
containing each component of the given color space/system in the name's order :
- RGB : [red, blue, green]
- XYZ : [X, Y, Z]
- LCH : [L, C, H]
- LUV : [L, u, v]
- HSLuv/HPLuv : [H, S, L]
xyzToRgb(List<double> tuple)
rgbToXyz(List<double> tuple)
xyzToLuv(List<double> tuple)
luvToXyz(List<double> tuple)
luvToLch(List<double> tuple)
lchToLuv(List<double> tuple)
hsluvToLch(List<double> tuple)
lchToHsluv(List<double> tuple)
hpluvToLch(List<double> tuple)
lchToHpluv(List<double> tuple)
lchToRgb(List<double> tuple)
rgbToLch(List<double> tuple)
hsluvToRgb(List<double> tuple)
rgbToHsluv(List<double> tuple)
hpluvToRgb(List<double> tuple)
rgbToHpluv(List<double> tuple)
hsluvToHex(List<double> tuple)
hpluvToHex(List<double> tuple)
hexToHsluv(String s)
hexToHpluv(String s)
rgbToHex(List<double> tuple)
hexToRgb(String hex)
Issues and Pull Requests are welcome. You can report here.
Copyright 2020 Bernardo Ferrari
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