Flutter CupertinoPicker with looping: true 给出错误的索引值

如何解决Flutter CupertinoPicker with looping: true 给出错误的索引值

循环设置为 true 的 Cupertinopicker 在您滚动到列表的开头或结尾时会给出负值和超出范围的值。问题在于从 FixedExtentScrollController 获取所选项目。

                Container(
              margin: const EdgeInsets.symmetric(horizontal: 10),height: 300,child: NotificationListener<ScrollNotification>(
                onNotification: (scrollNotification) {
                  if (scrollNotification is ScrollEndNotification) {
                    //Will only update when user has stopped scrolling in picker.
                    setState(() {
                      _selectedCourseIndex = _tempCourseIndex;   //works all the time
                      // _selectedCourseIndex =
                      //     _pickerCoursesController.selectItem;   // can give invalid values when looping
                    });
                    return true;
                  } else {
                    return false;
                  }
                },child: Cupertinopicker(
                  looping: true,itemExtent: 30,useMagnifier: true,magnification: 1.10,scrollController: _pickerCoursesController,onselecteditemchanged: (index) {
                    _tempCourseIndex = index;
                  },children: <Widget>[
                    for (var i = 0; i < courses.length; i++)
                      Center(
                        child: Text(
                          courses[i],style: const TextStyle(
                              color: Colors.black,fontSize: 24),),],