build method

@override Widget build(BuildContext context)

Override this method to build widgets that depend on the state of the listenable (e.g., the current value of the animation).

Implementation

@override
Widget build(BuildContext context) {
  return LayoutBuilder(
    builder: (context, constrains) {
      final scanningGradientHeight =
          constrains.maxHeight * scanningHeightOffset;
      final animation = listenable as Animation<double>;
      final value = isGoingUpDown ? 1.0 - animation.value : animation.value;
      final scorePosition =
          (value * constrains.maxHeight * 2) - (constrains.maxHeight);

      final color = scanningColor ?? Colors.blue;

      final isAnimationGoingDown = checkGoingUpDown(animation: animation);
      var begin =
          isAnimationGoingDown ? Alignment.topCenter : Alignment.bottomCenter;
      var end =
          isAnimationGoingDown ? Alignment.bottomCenter : Alignment.topCenter;
      var colors = isAnimationGoingDown
          ? [
              color.withOpacity(0.05),
              color.withOpacity(0.1),
              color.withOpacity(0.4),
              color,
              color,
            ]
          : [
              color.withOpacity(0.02),
              color.withOpacity(0.1),
              color.withOpacity(0.4),
              color.withOpacity(0.4),
              color,
            ];
      return Stack(
        children: [
          Container(
            height: scanningGradientHeight,
            transform: Matrix4.translationValues(0, scorePosition, 0),
            decoration: BoxDecoration(
              gradient: LinearGradient(
                begin: begin,
                end: end,
                stops: const [
                  0.0,
                  0.2,
                  0.9,
                  0.95,
                  1,
                ],
                colors: colors,
              ),
            ),
          ),
        ],
      );
    },
  );
}