C#实现改变DataGrid某一行和单元格颜色的方法

<DataGrid AutoGenerateColumns="False" Height="642" HorizontalAlignment="Left" Margin="131,57,0,0" Name="dataGrid1" VerticalAlignment="Top" Width="799" CanUserAddRows="True" LoadingRow="dataGrid1_LoadingRow" GridLinesVisibility="None">
  <DataGrid.ColumnHeaderStyle >
 <Style TargetType="DataGridColumnHeader">
   <Setter Property="Height" Value="50"></Setter>
 </Style>
  </DataGrid.ColumnHeaderStyle>
  <DataGrid.Columns>
 <DataGridTextColumn Header="id" Binding="{Binding Path=id}" ElementStyle="{StaticResource dgCell}"></DataGridTextColumn>
 <DataGridTextColumn Header="name" Binding="{Binding Path=name}" ElementStyle="{StaticResource dgCell}"></DataGridTextColumn>
  </DataGrid.Columns>
</DataGrid>

DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("id", typeof(int)));
dt.Columns.Add(new DataColumn("name", typeof(string)));

for (int i = 0; i < 6; i++)
{
 DataRow dr = dt.NewRow();
 if (i == 3)
 {
   dr["id"] = DBNull.Value;
   dr["name"] = DBNull .Value ;
   dt.Rows.Add(dr);
 }
 else
 {
   dr["id"] = i;
   dr["name"] = "tom" + i.ToString();
   dt.Rows.Add(dr);
 }
}

this.dataGrid1.CanUserAddRows = false;
this.dataGrid1.ItemsSource = dt.DefaultView;

for (int i = 0; i < this.dataGrid1.Items.Count; i++)
{
 DataRowView drv = dataGrid1.Items[i] as DataRowView;
 DataGridRow row = (DataGridRow)this.dataGrid1.ItemContainerGenerator.ContainerFromIndex(i);

 if (i == 2)
 {
   row.Height = 50;
   row.Background = new SolidColorBrush(Colors.Blue);
   drv["id"] = 333;
 }

 if (drv["id"] == DBNull.Value)
 {
   row.Background = new SolidColorBrush(Colors.Green);
   row.Height = 8;
 }
}

for (int i = 0; i < this.dataGrid1.Items.Count; i++)
{
 DataRowView drv = dataGrid1.Items[i] as DataRowView;
 DataGridRow row = (DataGridRow)this.dataGrid1.ItemContainerGenerator.ContainerFromIndex(i);
　　　　　　　　　if (i == 4)
 {
   DataGridCellsPresenter presenter = GetVisualChild<DataGridCellsPresenter>(row);
   DataGridCell cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(1);
   cell.Background = new SolidColorBrush(Colors.Red);
 }
}

public static T GetVisualChild<T>(Visual parent) where T : Visual
{
  T childContent = default(T);
  int numVisuals = VisualTreeHelper.GetChildrenCount(parent);
  for (int i = 0; i < numVisuals; i++)
  {
 Visual v = (Visual)VisualTreeHelper.GetChild(parent, i);
 childContent = v as T;
 if (childContent == null)
 {
   childContent = GetVisualChild<T>(v);
 }
 if (childContent != null)
 {
   break;
 }
  }

  return childContent;
}

//创建数据源、绑定数据源
    
if (!Window.GetWindow(dataGrid1).IsVisible)
{
 Window.GetWindow(dataGrid1).Show();
}
dataGrid1.UpdateLayout();

//可以获取某一行、某一行的单元格