将颜色更改为datagrid行中的特定单元格

Question

I am using this code deployment on here. But the casting in GetCell, get null in the row and fails to change the color of the cell. What I want to do is get the cell, then according to their value to change the cell color to red or green.

    public void ColorChange()
    {
        DataGridCell cell = GetCell(11, 1, dgLectura);
        cell.Background = new SolidColorBrush(Colors.Red);
    }

    public DataGridCell GetCell(int rowIndex, int columnIndex, DataGrid dg)
    {
        //DataGridRow row = dg.ItemContainerGenerator.ContainerFromIndex(rowIndex) as DataGridRow;

        DataGridRow row = (DataGridRow)dg.ItemContainerGenerator.ContainerFromIndex(rowIndex);
        if (row == null)
        {
            dg.UpdateLayout();
            dg.ScrollIntoView(dg.Items[rowIndex]);
            row = (DataGridRow)dg.ItemContainerGenerator.ContainerFromIndex(rowIndex);
        }
        DataGridCellsPresenter p = GetVisualChild<DataGridCellsPresenter>(row);
        DataGridCell cell = p.ItemContainerGenerator.ContainerFromIndex(columnIndex) as DataGridCell;
        return cell;
    }
    static T GetVisualChild<T>(Visual parent) where T : Visual
    {
        T child = default(T);
        int numVisuals = VisualTreeHelper.GetChildrenCount(parent);
        for (int i = 0; i < numVisuals; i++)
        {
            Visual v = (Visual)VisualTreeHelper.GetChild(parent, i);
            child = v as T;
            if (child == null)
            {
                child = GetVisualChild<T>(v);
            }
            if (child != null)
            {
                break;
            }
        }
        return child;
    }

Answer 1

This worked for me:

I used here a MultiConverter here in order to compare two data grids and i changed the color in each cell that the values where different. But you can use this for your scenario.

 public class NameToBrushMultiValueConverter : IMultiValueConverter
 {
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        var dataContext = values[0];
        var dg = (DataGrid)values[1];
        var i = (DataGridCell)values[2];
        var col = i.Column.DisplayIndex;
        var row = dg.Items.IndexOf(i.DataContext);
        if (row >= 0 && col >= 0)
        {
            DataTable td1 = ((CheckXmlAppWpf.ViewModel.MainWindowViewModel)(dataContext)).GenericDataTable;
            DataTable td2 = ((CheckXmlAppWpf.ViewModel.MainWindowViewModel)(dataContext)).GenericDataTable2;

            if (!td1.Rows[row][col].Equals(td2.Rows[row][col]))
            {
                GetCell(dg, row, col).Background = Brushes.Yellow;
            }
        }

        return SystemColors.AppWorkspaceColor;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new System.NotImplementedException();
    }


    public DataGridCell GetCell(DataGrid dg, int row, int column)
    {
        DataGridRow rowContainer = GetRow(dg, row);
        if (rowContainer != null)
        {
            DataGridCellsPresenter presenter = GetVisualChild<DataGridCellsPresenter>(rowContainer);
            if (presenter == null)
            {
                dg.ScrollIntoView(rowContainer, dg.Columns[column]);
                presenter = GetVisualChild<DataGridCellsPresenter>(rowContainer);
            }
            DataGridCell cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(column);
            return cell;
        }
        return null;
    }

    public static DataGridRow GetRow(DataGrid dg, int index)
    {
        DataGridRow row = (DataGridRow)dg.ItemContainerGenerator.ContainerFromIndex(index);
        if (row == null)
        {
            dg.UpdateLayout();
            dg.ScrollIntoView(dg.Items[index]);
            row = (DataGridRow)dg.ItemContainerGenerator.ContainerFromIndex(index);
        }
        return row;
    }

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