SwiperLayout.TINDER 模式_animationCount 写死成5，导致一个item时，还能滑动。

[sail-coder]

@OverRide
void afterRender() {
super.afterRender();

_startIndex = -3;
_animationCount = 5;
opacity = [0.0, 0.9, 0.9, 1.0, 0.0, 0.0];
scales = [0.80, 0.80, 0.85, 0.90, 1.0, 1.0, 1.0];
rotates = [0.0, 0.0, 0.0, 0.0, 20.0, 25.0];
_updateValues();

}

后续的事件处理为：
Widget _buildAnimation(BuildContext context, Widget w) {
List list = [];

double animationValue = _animation.value;

for (int i = 0; i < _animationCount; ++i) {
  int realIndex = _currentIndex + i + _startIndex;
  realIndex = realIndex % widget.itemCount;
  if (realIndex < 0) {
    realIndex += widget.itemCount;
  }

  list.add(_buildItem(i, realIndex, animationValue));
}

return new GestureDetector(
  behavior: HitTestBehavior.opaque,
  onPanStart: _onPanStart,
  onPanEnd: _onPanEnd,
  onPanUpdate: _onPanUpdate,
  child: new ClipRect(
    child: new Center(
      child: _buildContainer(list),
    ),
  ),
);

}

导致item为1时还可以进行滑动。