WPF DataGrid CheckBox 多选 反选 全选

   <Window.Resources>
        <DataTemplate x:Key="CheckBoxDataTemplate">
            <Grid>
                <CheckBox
                             Click="CheckBox_Checked"
                              Uid="{Binding id}"
                            IsChecked="{Binding IsSelect , Mode=TwoWay}">
                </CheckBox>
            </Grid>
        </DataTemplate>
      
        <Style x:Key="CheckBoxStyle" TargetType="{x:Type DataGridCell}">
            <Setter Property="ContentTemplate" Value="{StaticResource  CheckBoxDataTemplate}"/>
        </Style>

    </Window.Resources>
    <Grid>
        <DataGrid  x:Name="TST"  >
            <DataGrid.Columns>
                <DataGridCheckBoxColumn CellStyle="{StaticResource  CheckBoxStyle}"  Header="选择">
                    <DataGridCheckBoxColumn.HeaderTemplate>
                        <DataTemplate>
                            <CheckBox Content="全选" Uid="-1" Click="CheckBox_Checked"/>
                        </DataTemplate>
                    </DataGridCheckBoxColumn.HeaderTemplate>
                </DataGridCheckBoxColumn>
                <DataGridTextColumn Width="15*" Header="顺序" Binding="{Binding id}" />
            </DataGrid.Columns >
        </DataGrid>
    </Grid>

 public class TEST : INotifyPropertyChanged
        {
            public event PropertyChangedEventHandler PropertyChanged;
            private bool? isSelect;
            public int id { get; set; }
            public bool? IsSelect
            {
                get { return isSelect; }
                set
                {
                    isSelect = value; OnChanged(new PropertyChangedEventArgs("IsSelect"));
                }
            }

            protected void OnChanged(PropertyChangedEventArgs arg)//具体方法
            {
                PropertyChanged?.Invoke(this, arg);
            }
        }

    ObservableCollection<TEST> ts = new ObservableCollection<TEST>();

        public MainWindow()
        {
            InitializeComponent();

            TST.AutoGenerateColumns = false;

            TST.CanUserAddRows = false;
            for (var i = 0; i < 100; i++)
            {
                ts.Add(new TEST() { IsSelect = false, id = i });
            }
            TST.ItemsSource = ts;

        }


        private void CheckBox_Checked(object sender, RoutedEventArgs e)
        {
            var Check = (sender as CheckBox);

            var CUID = int.Parse(Check.Uid);

            //全选
            if (CUID==-1)
            {
                foreach (var item in ts)
                    item.IsSelect = true;
                Check.Uid = "-2";
                return;
            }
            //全否选
            if (CUID==-2)
            {
                foreach (var item in ts)
                    item.IsSelect = false;
                Check.Uid = "-1";
                return;
            }

            var IsSelcted = ts[CUID].IsSelect;

            ts[CUID].IsSelect = (IsSealed ? false : true);

            var IsSelects = from s in ts
                            where s.IsSelect == true
                            select s;

            if(IsSelects.Count()==5)
            {
                var Text = String.Empty;
                foreach (var ITEM in IsSelects)
                    Text += ITEM.id + " \n";

                MessageBox.Show(Text);
            }

        }