sdd_anim_build.dart

  Widget _buildAnimation(BuildContext context, Widget child) {
    return Container(
      child: SkewTransition(
        skew: skewTransform1,
        child: SkewTransition(
          skew: skewTransform2,
          child: Container(
            width: _kActionSize * 4,
            height: 256.0,
            color: Colors.black87,
            child: Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  _buildListTile(context, 0),
                  Stack(
                    children: List.generate(_kCount, (i) {
                      return SlideTransition(
                        position: dyPositions1[i],
                        child: SlideTransition(
                          position: dxPositions[i],
                          child: SlideTransition(
                            position: dyPositions2[i],
                            child: _buildWidget(context, i),
                          ),
                        ),
                      );
                    }),
                  ),
                  _buildListTile(context, 2),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }