GestureDetector.dart

   @override
    Widget build(BuildContext context) {
      _scale = 1 - _controller.value;
      return GestureDetector(
        onTapDown: _onTapDown,
        onTapUp: _onTapUp,
        child: Transform.scale(
          scale: _scale,
          child: _animatedButtonUI,
        ),
      );
    }