BudgetApp/lib/theme/custom_colors.dart

import 'package:flutter/material.dart';

// Расширение темы для добавления пользовательских цветов.
@immutable
class CustomColors extends ThemeExtension<CustomColors> {
  const CustomColors({
    required this.income,
    required this.expense,
  });

  final Color? income;
  final Color? expense;

  @override
  CustomColors copyWith({Color? income, Color? expense}) {
    return CustomColors(
      income: income ?? this.income,
      expense: expense ?? this.expense,
    );
  }

  @override
  CustomColors lerp(ThemeExtension<CustomColors>? other, double t) {
    if (other is! CustomColors) {
      return this;
    }
    return CustomColors(
      income: Color.lerp(income, other.income, t),
      expense: Color.lerp(expense, other.expense, t),
    );
  }
}