Flutter-如何更改活动的BottomNavBar项目的背景颜色？

Question

我已经搜索了很长时间，但可惜找不到相关的答案。如何更改活动路线项目的背景颜色？在图片上查看或在iPhone上查看当前的Audible或Clock应用程序。我正在使用CupertinoTabBar，但找不到该问题的任何解决方案。我只想在我的活动物品后面放一个圆角正方形。

Audible App - Bottom Navigation Bar

按照我当前的导航栏代码

CupertinoTabScaffold(
          tabBar: CupertinoTabBar(
            iconSize: 30,
            activeColor: SymeColorPurple,
            backgroundColor: Colors.white,
            inactiveColor: Colors.black12,
            items: [
              BottomNavigationBarItem(
                icon: Padding(
                  padding: const EdgeInsets.only(top: 6.0),
                  child: Icon(
                    Icons.settings
                  ),
                ),
                title: Text(
                  "Inventory",
                  style: const TextStyle(fontWeight: FontWeight.w600),
                ),
              ),
              BottomNavigationBarItem(
                icon: Padding(
                  child: Icon(Icons.home),
                  padding: const EdgeInsets.only(top: 6.0),
                ),
                title: Text(
                  "Home",
                  style: const TextStyle(fontWeight: FontWeight.w600),
                ),
              ),
              BottomNavigationBarItem(
                icon: Padding(
                  child: Icon(
                    Icons.camera_alt
                  ),
                  padding: const EdgeInsets.only(top: 6.0),
                ),
                title: Text(
                  "Camera",
                  style: const TextStyle(fontWeight: FontWeight.w600),
                ),
              ),
            ],
          ),
          tabBuilder: (context, index) {
            switch (index) {
              case 0:
                return InventoryPage();
                break;
              case 1:
                return HomeView();
                break;
              case 2:
                return CameraPage();
                break;
              default:
                return HomeView();
                break;
            }
          }),