SliverOpacity

SliverOpacity是sliver系列组件，子控件为sliver组件，可设置子组件透明度，

SliverOpacity(
  opacity: 0.5,
  sliver: SliverList(
    delegate: SliverChildBuilderDelegate((content, index) {
      return Container(
        height: 65,
        color: Colors.primaries[index % Colors.primaries.length],
      );
    }, childCount: 50),
  ),
),