build method

@override Widget build({ required Animation<double> animation, required Widget child, Map<String, Object?> params = const {}, })

Builds the animated widget for the forward direction.

animation — 0.0 → 1.0 where 0.0 = invisible/start, 1.0 = visible/end. child — the widget being animated. params — optional configuration map (typed by each plugin).

Concrete subclasses must override this method.

Implementation

@override
Widget build({
  required Animation<double> animation,
  required Widget child,
  Map<String, Object?> params = const {},
}) {
  final base =
      (params['base'] as Color?) ?? const Color(0xFFE0E0E0);
  final highlight =
      (params['highlight'] as Color?) ?? const Color(0xFFF5F5F5);

  return AnimatedBuilder(
    animation: animation,
    builder: (_, c) {
      final t = animation.value;
      // Sweep from left (-1) to right (+1) over the animation
      final sweep = -1.0 + t * 3.0; // goes -1 → 2
      return ShaderMask(
        blendMode: BlendMode.srcATop,
        shaderCallback: (rect) => LinearGradient(
          begin: Alignment(sweep - 1.0, 0.0),
          end: Alignment(sweep + 1.0, 0.0),
          colors: [base, highlight, base],
          stops: const [0.0, 0.5, 1.0],
        ).createShader(rect),
        child: c,
      );
    },
    child: child,
  );
}