使用行-列索引-WPF从后端为DataGrid中的单个单元格设置背景

// 获取特定行和列的DataGridCell对象
DataGridCellInfo cellInfo = new DataGridCellInfo(dataGrid.Items[rowIndex], dataGrid.Columns[columnIndex]);
DataGridCell cell = GetCell(dataGrid, cellInfo);

// 设置单元格的背景颜色
cell.Background = new SolidColorBrush(Colors.Red);

private DataGridCell GetCell(DataGrid dataGrid, DataGridCellInfo cellInfo)
{
    DataGridRow row = (DataGridRow)dataGrid.ItemContainerGenerator.ContainerFromItem(cellInfo.Item);
    if (row != null)
    {
        int columnIndex = dataGrid.Columns.IndexOf(cellInfo.Column);
        if (columnIndex > -1)
        {
            DataGridCellsPresenter presenter = GetVisualChild<DataGridCellsPresenter>(row);
            if (presenter != null)
            {
                DataGridCell cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(columnIndex);
                if (cell != null)
                {
                    return cell;
                }
            }
        }
    }
    return null;
}

private 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 visual = (Visual)VisualTreeHelper.GetChild(parent, i);
        child = visual as T;
        if (child == null)
        {
            child = GetVisualChild<T>(visual);
        }
        if (child != null)
        {
            break;
        }
    }
    return child;
}