Forward fix for wide gamut changes in colors

[gaaclarke]

fixes #9

changes:

• Renames ColorModel.withValues to ColorModel.fromValues
• Renames LabColor.a to LabColor.chromaticityA
• Renames LabColor.b to LabColor.chromaticityB
• Renames OklabColor.a to OklabColor.chromaticityA
• Renames OklabColor.b to OklabColor.chromaticityB
• Adds Color.a, Color.r, Color.g, Color.b, Color.withValues, Color.colorSpace

I chose fromValues instead of withValues since "with*" is used to mean tweaking an existing color, whereas that method is creating completely new color.

[gaaclarke]

friendly ping @james-alex @isaacroberts

[lukemmtt]

FYI, after upgrading my project to the new stable release Flutter 3.27.0, the underlying issue here resulted in build errors in my project. In my tests, @gaaclarke's PR here resolves these errors. Thus, this PR (or another similar fix) needs to be merged to resolve build incompatibilities between color_models and Flutter 3.27.0.

In case it might help anyone in the meantime, I resolved my project's build errors with a dependency override pointing to gaaclarke's PR code (but substituting with my own fork), like so:

dependencies:
  color_models:
    git:
      url: https://github.com/gaaclarke/color_models.git
      ref: wide-gamut
      path: color_models
  flutter_color_models:
    git:
      url: https://github.com/gaaclarke/color_models.git
      ref: wide-gamut
      path: flutter_color_models
      
dependency_overrides:
  color_models:
    git:
      url: https://github.com/gaaclarke/color_models.git
      ref: wide-gamut
      path: color_models
  flutter_color_models:
    git:
      url: https://github.com/gaaclarke/color_models.git
      ref: wide-gamut
      path: flutter_color_models

[tivorreda64]

Hi! Just notifying something that happened to me.

I ran into an issue after the renaming of the a and b fields in LabColor with this extension. The code still compiled but produced incorrect behavior because I was accessing the wrong fields in LabColor.

For example, in the following function calculating Euclidean distance between two LAB colors, it caused a wrong result and still compiled:

  // Euclidean distance between two LAB colors
  double euclideanDistance(LabColor labColor, LabColor baseColor) {
    return sqrt(pow(labColor.lightness - baseColor.lightness, 2) +
        pow(labColor.a - baseColor.a, 2) +
        pow(labColor.b - baseColor.b, 2));
  }

[gaaclarke]

I'm sorry @tivorreda64. Unfortunately this package is abandoned and has minimal testing. I'm not going to invest any more time on an abandoned package with sparse tests. If you can come up with a test that demonstrates the problem we can post it here and maybe someone who needs this package can find the time to fix it. I'm happy to append any patches to this PR to keep the info all in one place.

[gaaclarke]

The equivalent has landed, no need for this pr anymore.