Migration guide for wide gamut CupertinoDynamicColor

Certain properties and methods in CupertinoDynamicColor were deprecated to align with the Color class due to wide gamut color spaces support added in Flutter 3.27.

The Color class was updated to support wide gamut color spaces, but some corresponding deprecations were not initially applied to CupertinoDynamicColor due to its implementation rather than due to the extension of Color.

1. The CupertinoDynamicColor.red field is deprecated in favor of CupertinoDynamicColor.r.
2. The CupertinoDynamicColor.green is deprecated in favor of CupertinoDynamicColor.g.
3. The CupertinoDynamicColor.blue is deprecated in favor of CupertinoDynamicColor.b.
4. The CupertinoDynamicColor.opacity is deprecated in favor of CupertinoDynamicColor.a.
5. The CupertinoDynamicColor.withOpacity() is deprecated in favor of CupertinoDynamicColor.withValues().

If your app accesses a single color component, consider taking advantage of the floating-point components. In the short term, you can scale the components themselves.

int _floatToInt8(double x) {
  return (x * 255.0).round().clamp(0, 255);
}
​
const CupertinoDynamicColor color = CupertinoColors.systemBlue;
final intRed = _floatToInt8(color.r);
final intGreen = _floatToInt8(color.g);
final intBlue = _floatToInt8(color.b);

Before Flutter 3.27, Color had the concept of "opacity", which showed up in the methods opacity and withOpacity(). Since Flutter 3.27, the alpha channel has been stored as a floating-point value. Using .a and .withValues() will give the full expression of a floating-point value and won't be quantized (restricted to a limited range). That means "alpha" expresses the intent of "opacity" more correctly.

// Before: Access the alpha channel as a (converted) floating-point value.
final x = color.opacity;
​
// After: Access the alpha channel directly.
final x = color.a;

// Before: Create a new color with the specified opacity.
final x = color.withOpacity(0.5);
​
// After: Create a new color with the specified alpha channel value,
// accounting for the current or specified color space.
final x = color.withValues(alpha: 0.5);

Landed in version: 3.36.0-0.1.pre
Stable release: 3.38

Relevant guides:

• Migration guide for wide gamut Color

Relevant issues:

• Implement wide gamut color support in the Framework
• CupertinoDynamicColor is missing deprecation notices

Relevant PRs:

• Add missing deprecations to CupertinoDynamicColor