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 from = (params['from'] as double?) ?? 0.0;
  final to = (params['to'] as double?) ?? 1.0;
  final alignment =
      (params['alignment'] as Alignment?) ?? Alignment.center;

  // Fast path: 0→1 with center alignment
  if (from == 0.0 && to == 1.0 && alignment == Alignment.center) {
    return ScaleTransition(scale: animation, child: child);
  }

  final tween = Tween<double>(begin: from, end: to);
  return ScaleTransition(
    scale: tween.animate(animation),
    alignment: alignment,
    child: child,
  );
}