Изменение цвета ячейки WPF Datagrid

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Уважаемый друг,
В настоящее время я работаю над приложением для торговли акциями. В этом приложении я работаю над наблюдением за рынком. Для этого наблюдения за рынком я использую Wpftoolkit Datagrid. Теперь я успешно показываю данные.
Теперь проблема в том, что я хочу изменить цвет фона парикулярной ячейки на основе разницы текущего значения этой ячейки и предыдущего значения.Может ли кто-нибудь подсказать мне этот трюк
Мой код XAML является

<Window x:Class="WpfApplication2.Window1"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

    xmlns:wpftoolkit="http://schemas.microsoft.com/wpf/2008/toolkit"

    Title="Window1" Height="300" Width="500" removed="Black" Foreground="Gold">
    <Border>
        <DockPanel>
            <Button Name="btnStart" DockPanel.Dock="Top" Content="Start" Click="btnStart_Click"></Button>
            <wpftoolkit:DataGrid x:Name="grid" removed="Black" Foreground="White"  AutoGenerateColumns="False" SelectionUnit="Cell" IsReadOnly="True" GridLinesVisibility="None" TargetUpdated="grid_TargetUpdated" SourceUpdated="grid_SourceUpdated">
                <wpftoolkit:DataGrid.Columns>
                    <wpftoolkit:DataGridTextColumn Header="Company Name" Foreground="White" x:Name="cmpname" Binding ="{Binding Path=cmpName}" />
                    <wpftoolkit:DataGridTextColumn Header="TOKEN" Foreground="White" x:Name="token" Binding ="{Binding Path=Token}"/>
                    <wpftoolkit:DataGridTextColumn Header="BYE QTY" x:Name="bqty" Binding ="{Binding Path=Bqty,NotifyOnSourceUpdated =True}"/>
                    <wpftoolkit:DataGridTextColumn Header="BUY PRICE"  x:Name="bprice" Binding ="{Binding Path=BPrice, NotifyOnSourceUpdated =True}"/>
                    <wpftoolkit:DataGridTextColumn Header="SELL QTY" x:Name="sqty" Binding ="{Binding Path=Sqty,NotifyOnSourceUpdated =True}"/>
                    <wpftoolkit:DataGridTextColumn Header="SELL PRICE" x:Name="sprice" Foreground="White" Binding ="{Binding Path=SPrice,NotifyOnSourceUpdated =True}" Width="1*"/>
                </wpftoolkit:DataGrid.Columns>
                <wpftoolkit:DataGrid.CellStyle>
                    <Style TargetType="{x:Type wpftoolkit:DataGridCell}">
                        <Setter Property="Background" Value="Black"></Setter>                        
                    </Style>                    
                </wpftoolkit:DataGrid.CellStyle>
                <wpftoolkit:DataGrid.Style>
                    <Style TargetType="{x:Type wpftoolkit:DataGrid}">
                        <Setter Property="GridLinesVisibility" Value="None"></Setter>
                    </Style>
                </wpftoolkit:DataGrid.Style>
            </wpftoolkit:DataGrid>
        </DockPanel>
    </Border>
</Window>

а код C# - это

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Data;
using System.Net;
using System.Net.Sockets;
using System.Data.SqlServerCe;
using System.ComponentModel;
using Microsoft.Windows.Controls;
using System.Windows.Controls.Primitives;
using VISION_MARKET_WATCH;
using System.Collections.Specialized;
namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        DataTable dt = new DataTable();
        BackgroundWorker bw = new BackgroundWorker();
        public Window1()
        {
            InitializeComponent();
            DataGrid myGrid = new DataGrid(); 
            CollectionView myCollectionView = (CollectionView)CollectionViewSource.GetDefaultView(myGrid.Items);
            
            ((INotifyCollectionChanged)myCollectionView).CollectionChanged += new NotifyCollectionChangedEventHandler(DataGrid_CollectionChanged); 
            dt.Columns.Add("cmpName", typeof(String));
            dt.Columns.Add("Token", typeof(String));
            dt.Columns.Add("Bqty", typeof(String));
            dt.Columns.Add("BPrice", typeof(String));
            dt.Columns.Add("Sqty", typeof(String));
            dt.Columns.Add("SPrice", typeof(String));
            FillGrid();
            bw.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);   
            bw.WorkerReportsProgress = true ;
            bw.ProgressChanged += new ProgressChangedEventHandler(BackgroundWorker1_ProgressChanged);
        }
        private void FillGrid()
        {
            string s = "c:\\SimDB.sdf";
            //string s = Path.GetFullPath(System.Windows.Forms.Application.StartupPath + "\\" + "\\SimDB.sdf");
            string dbfile = "Persist Security Info = False;Data Source=" + s + ";";
            SqlCeConnection connection = new SqlCeConnection("datasource=" + dbfile);
            connection.Open();
            SqlCeDataAdapter da = new SqlCeDataAdapter("select * from NSEList inner join profile on NSEList.token = profile.token where shortcode = 'EQ'", connection);
            DataSet ds = new DataSet();
            da.Fill(ds);
            connection.Close();
            da = null;
            
            for (int cnt = 0; cnt < ds.Tables[0].Rows.Count - 1; cnt++)
            {
                DataRow drow = dt.NewRow();
                drow["cmpName"] = ds.Tables[0].Rows[cnt]["ShortName"].ToString();
                drow["Token"] = ds.Tables[0].Rows[cnt]["Token"].ToString();
                drow["Bqty"] = "";
                drow["BPrice"] = "";
                drow["Sqty"] = "";
                drow["SPrice"] = "";
                dt.Rows.Add(drow);
               
            }
            grid.ItemsSource = dt.DefaultView;
            
            //grid.Background = Brushes.Black;1
            //grid.BorderStyle = System.Windows.Forms.BorderStyle.None;
        }
        private void btnStart_Click(object sender, RoutedEventArgs e)
        {
            bw.RunWorkerAsync();
        }
        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            processBroadCast();
            
        }
        private void BackgroundWorker1_ProgressChanged(System.Object obj, System.ComponentModel.ProgressChangedEventArgs e)
        {
            this.Dispatcher.BeginInvoke((Action)delegate() {
                dt = (DataTable)e.UserState;
                
                //grid.Items.Refresh();
            });
            DataTrigger dg = new DataTrigger();
            
        }
        private DataTable processBroadCast()
        {
            UdpClient cli = new UdpClient(7864);
            IPEndPoint ep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 7864);
            while (true)
            {
                byte[] data = cli.Receive(ref ep);
                MWProperties mwproc = new MWProperties();
                BASEMAIN.CallingMethod(ref mwproc, data);
                DataTable dt2 = ChangeGrid(ref mwproc);
                data = null;
                mwproc = null;
                bw.ReportProgress(0, dt2);
            }
            //peer = null;           
        }
        //public DataGridRow GetRow(int index)
        //{
        //    DataGridRow row = (DataGridRow)DataGrid_Standard.ItemContainerGenerator.ContainerFromIndex(index);
        //    if (row == null)
        //    {
        //        // may be virtualized, bring into view and try again
        //        DataGrid_Standard.ScrollIntoView(DataGrid_Standard.Items[index]);
        //        row = (DataGridRow)DataGrid_Standard.ItemContainerGenerator.ContainerFromIndex(index);
        //    }
        //    return row;
        //}
        //public DataGridCell GetCell(int row, int column)
        //{
        //    DataGridRow rowContainer = GetRow(row);
        //    if (rowContainer != null)
        //    {
                
        //        DataGridCellsPresenter presenter = GetVisualChild<DataGridCellsPresenter>(rowContainer);
        //        // try to get the cell but it may possibly be virtualized
        //        DataGridCell cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(column);
        //        if (cell == null)
        //        {
        //            // now try to bring into view and retreive the cell
        //            DataGrid_Standard.ScrollIntoView(rowContainer, DataGrid_Standard.Columns[column]);
        //            cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(column);
        //        }
        //        return cell;
        //    }
        //    return null;
        //}
        private DataTable ChangeGrid(ref MWProperties mwproc)
        {
            DataTable dt1 = dt;
            short i = mwproc.Token;
            //Microsoft.Windows.Controls.DataGridCell cell = new Microsoft.Windows.Controls.DataGridCell();
            try
            {
                if (mwproc == null)
                {
                }
                else
                {                                       
                    for (int k = 0; k < grid.Items.Count - 1; k++)
                    {
                        if (dt1.Rows[k]["Token"] != null)
                        {
                            if (dt1.Rows[k]["Token"].ToString() == i.ToString())
                            {
                                dt1.Rows[k]["Bqty"] = mwproc.MBPINFORMATION[0].Quantity.ToString();
                                dt1.Rows[k]["BPrice"] = (decimal.Round(mwproc.MBPINFORMATION[0].Price, 2) / 100).ToString();
                                dt1.Rows[k]["Sqty"] = mwproc.MBPINFORMATION[5].Quantity.ToString();
                                dt1.Rows[k]["SPrice"] = (decimal.Round(mwproc.MBPINFORMATION[5].Price, 2) / 100).ToString();
                            }
                        }                                                         
                    }                                        
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            return dt1;
        }
        private void DataGrid_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            
        }
        private void grid_TargetUpdated(object sender, DataTransferEventArgs e)
        {
           
        }
        private void grid_SourceUpdated(object sender, DataTransferEventArgs e)
        {
            if (e.OriginalSource != null && e.TargetObject != null)
            {
                DependencyProperty prop = e.Property;
                DataGrid src = (DataGrid)e.Source;
                try
                {
                    TextBlock obnew = (TextBlock)e.OriginalSource;
                    TextBlock objold = (TextBlock)e.TargetObject;
                    if (obnew.Text != objold.Text)
                    {
                        double pre, no;
                        Boolean b1 = double.TryParse(objold.Text.ToString(), out pre);
                        Boolean b2 = double.TryParse(obnew.Text.ToString(), out no);
                        if (b1 == true && b2 == true)
                        {
                            if (pre > no)
                            {
                                obnew.Background = Brushes.Red;
                            }
                            else
                            {
                                obnew.Background = Brushes.Green;
                            }
                        }
                    }
                }
                catch (Exception ex)
                {
                }

            }          
        }
    }
}

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