Flutter/Dart - 滑动动画的反向？

Question

我从 Flutter.dev 网站获得了以下示例。它提供了流畅的onSwipeUp动画片。但是如何修改代码给我一个流畅的onSwipeDown动画片？我尝试反转 var begin和 var end但它似乎没有奏效，当我刷卡时什么也没发生。这是刷卡代码；

onSwipeDown: (){
           Navigator.of(context).push(_opidRoute(routeaudioid: opid));
            },

这是动画；

    Route _opidRoute({String routeaudioid, String mastertitle}) {
  return PageRouteBuilder(
    opaque: false,
    pageBuilder: (context, animation, secondaryAnimation) => SingleOpid(opid: routeaudioid
    ),
    transitionsBuilder: (context, animation, secondaryAnimation, child) {
      var begin = Offset(0.0, 1.0);
      var end = Offset.zero;
      var curve = Curves.ease;

      var tween = Tween(begin: begin, end: end).chain(CurveTween(curve: curve));

      return SlideTransition(
        position: animation.drive(tween),
        child: child,
      );
    },
  );
}

有什么想法可以扭转方向吗？

Answer 1

尝试

var begin = Offset(0.0, -1.0);